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Sample records for acid formic acid

  1. Formic acid

    Integrated Risk Information System (IRIS)

    Formic acid ; CASRN 64 - 18 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  2. 21 CFR 573.480 - Formic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Formic acid. 573.480 Section 573.480 Food and... Listing § 573.480 Formic acid. The food additive, formic acid, may be safely used in accordance with the...) The top foot of silage stored should not contain formic acid and (2) Silage should not be fed to...

  3. 21 CFR 573.480 - Formic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Formic acid. 573.480 Section 573.480 Food and... Listing § 573.480 Formic acid. The food additive, formic acid, may be safely used in accordance with the...) The top foot of silage stored should not contain formic acid and (2) Silage should not be fed to...

  4. 21 CFR 573.480 - Formic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Formic acid. 573.480 Section 573.480 Food and... Listing § 573.480 Formic acid. The food additive, formic acid, may be safely used in accordance with the...) The top foot of silage stored should not contain formic acid and (2) Silage should not be fed to...

  5. 21 CFR 573.480 - Formic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Formic acid. 573.480 Section 573.480 Food and... Listing § 573.480 Formic acid. The food additive, formic acid, may be safely used in accordance with the...) The top foot of silage stored should not contain formic acid and (2) Silage should not be fed to...

  6. GLYCOLIC - FORMIC ACID FLOWSHEET DEVELOPMENT

    SciTech Connect

    Pickenheim, B.; Stone, M.; Newell, J.

    2010-11-08

    Flowsheet testing was performed to further develop the nitric/glycolic/formic acid flowsheet as an alternative to the nitric/formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be removed in the Sludge Receipt and Adjustment Tank (SRAT) with minimal hydrogen generation. All other processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Eight runs were performed in total, including the baseline run. The baseline nitric/formic flowsheet run was extremely difficult to process under existing DWPF acceptance criteria with this simulant at the HM levels of noble metals. While nitrite was destroyed and mercury was removed to near the DWPF limit, the rheology of the SRAT and SME products were well above design basis and hydrogen generation far exceeded the DWPF limit. In addition, mixing during the SME cycle was very poor. In this sense, the nitric/glycolic/formic acid flowsheet represents a significant upgrade over the current flowsheet. In the nitric/glycolic/formic flowsheet runs, mercury was successfully removed with almost no hydrogen generation and the SRAT and SME products yield stresses were within process limits or previously processed ranges. It is recommended that DWPF continue to support development of the nitric/glycolic/formic flowsheet. Although experience is limited at this time, this flowsheet meets or outperforms the current flowsheet in many regards, including off-gas generation, mercury removal, product rheology and general ease of processing. Additional flowsheet testing will allow for a more thorough understanding of the chemistry and effectiveness of the flowsheet over a range of sludge compositions and formic/glycolic ratios. This testing will also show whether the REDOX and metal solubility concerns with this change in the flowsheet can be addressed by just adjusting the volumes of

  7. 21 CFR 573.480 - Formic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Formic acid. 573.480 Section 573.480 Food and... Listing § 573.480 Formic acid. Formic acid may be safely used as a preservative in hay crop silage in an.... The top foot of silage stored should not contain formic acid and silage should not be fed to livestock...

  8. 21 CFR 186.1316 - Formic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Formic acid. 186.1316 Section 186.1316 Food and....1316 Formic acid. (a) Formic acid (CH2O2, CAS Reg. No. 64-18-6) is also referred to as methanoic acid or hydrogen carboxylic acid. It occurs naturally in some insects and is contained in the free acid...

  9. Shock compression of formic acid

    NASA Astrophysics Data System (ADS)

    Manner, Virginia W.; Sheffield, S. A.; Dattelbaum, Dana M.; Stahl, David B.

    2012-03-01

    Simple molecules such as formic acid, HCOOH, have been suggested to play important roles in the origin of life due to their high pressure and temperature chemistry. The hydrogen bonding characteristics and polymerization of HCOOH under static high pressure have been recently investigated using both molecular dynamics calculations and experimental work. These works suggest that symmetric hydrogen bonding of HCOOH (forming a linear chain polymer where all C-O bonds are equivalent) occurs at 16 - 21 GPa at room temperature. In order to examine the shock compression behavior of this simple carboxylic acid, we present a series of gas gun-driven plate impact experiments on formic acid with shock inputs in the range of 5.5 - 23.0 GPa. Using in-situ electromagnetic gauges, shock wave profiles (particle velocities) were measured at multiple positions as a function of shock input pressure, providing valuable information about its unreacted equation of state. No easily recognizable shock-induced reactions were observed in any of the four experiments, and the four points lie close to a universal liquid Hugoniot based only on the sound speed of formic acid.

  10. 21 CFR 186.1316 - Formic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Formic acid. 186.1316 Section 186.1316 Food and... Substances Affirmed as GRAS § 186.1316 Formic acid. (a) Formic acid (CH2O2, CAS Reg. No. 64-18-6) is also referred to as methanoic acid or hydrogen carboxylic acid. It occurs naturally in some insects and is...

  11. 21 CFR 186.1316 - Formic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Formic acid. 186.1316 Section 186.1316 Food and... Substances Affirmed as GRAS § 186.1316 Formic acid. (a) Formic acid (CH2O2, CAS Reg. No. 64-18-6) is also referred to as methanoic acid or hydrogen carboxylic acid. It occurs naturally in some insects and is...

  12. 21 CFR 186.1316 - Formic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Formic acid. 186.1316 Section 186.1316 Food and... Substances Affirmed as GRAS § 186.1316 Formic acid. (a) Formic acid (CH2O2, CAS Reg. No. 64-18-6) is also referred to as methanoic acid or hydrogen carboxylic acid. It occurs naturally in some insects and is...

  13. 21 CFR 186.1316 - Formic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Formic acid. 186.1316 Section 186.1316 Food and... Substances Affirmed as GRAS § 186.1316 Formic acid. (a) Formic acid (CH2O2, CAS Reg. No. 64-18-6) is also referred to as methanoic acid or hydrogen carboxylic acid. It occurs naturally in some insects and is...

  14. Shock Compression of Formic Acid

    NASA Astrophysics Data System (ADS)

    Manner, Virginia; Sheffield, Stephen; Dattelbaum, Dana; Engelke, Ray; Stahl, David; Shock; Detonation Physics Team

    2011-06-01

    Simple molecules such as formic acid, HCOOH, have been suggested to play important roles in the origin of life due to their high pressure and temperature chemistry. The hydrogen bonding characteristics and polymerization of HCOOH under high pressure have been recently investigated using both molecular dynamics calculations and experimental work. These works suggest that symmetric hydrogen bonding of HCOOH (forming a linear chain polymer where all C-O bonds are equivalent) occurs at 16 - 21 GPa at room temperature. In order to examine the shock compression behavior of this simple carboxylic acid, we present a series of gas gun-driven plate impact experiments on formic acid with shock inputs in the range of 10 - 20 GPa, overlapping in pressure with the earlier static experimental results. Using in-situ electromagnetic gauges, shock wave profiles (particle velocities) were measured at multiple Lagrangian positions as a function of shock input pressure, providing valuable information about its unreacted equation of state and shock-induced chemical reactions. The results are discussed in the context of the Hugoniot conditions, phase diagram and static high-pressure behavior, and related chemistry of other simple hydroxyl-/carboxyl-containing molecules.

  15. Urinary formic acid as an indicator of occupational exposure to formic acid and methanol

    SciTech Connect

    Liesivuori, J.; Savolainen, H.

    1987-01-01

    A sampling strategy was developed to detect personal exposure to methanol and formic acid vapors. Formic acid is the metabolic end product of methanol, and part of inhaled formic acid is excreted directly in urine, so that urinary formic acid would reveal exposure to both agents. A linear relationship to inhaled vapors, however, could be shown only if urinary sampling were delayed until 16 hr (next morning) after exposure. Exposure to methanol vapor at the current Finnish hygienic limit level (200 ppm) produced 80 mg formic acid/g creatinine; exposure to formic acid at the hygienic limit (5 ppm) caused 90 mg/g creatinine. The similarity of these figures may indicate a common toxicological foundation of these empirically set values.

  16. Elastic electron scattering from formic acid

    SciTech Connect

    Trevisan, Cynthia S.; Orel, Ann E.; Rescigno, Thomas N.

    2006-07-31

    Following our earlier study on the dynamics of low energy electron attachment to formic acid, we report the results of elastic low-energy electron collisions with formic acid. Momentum transfer and angular differential cross sections were obtained by performing fixed-nuclei calculations employing the complex Kohn variational method. We make a brief description of the technique used to account for the polar nature of this polyatomic target and compare our results with available experimental data.

  17. Atmospheric measurements of pyruvic and formic acid

    NASA Technical Reports Server (NTRS)

    Andreae, Meinrat O.; Li, Shao-Meng; Talbot, Robert W.

    1987-01-01

    Pyruvic acid, a product of the atmospheric oxidation of cresols and probably of isoprene, has been determined together with formic acid in atmospheric aerosols and rain as well as in the vapor phase. Both acids are present predominantly as vapor; only about 10-20 percent of the total atmospheric pyruvate and 1-2 percent of the total formate are in the particulate phase. The concentrations of pyruvic and formic acid are highly correlated, with typical formic-to-pyruvic ratios of 10-30 in the gas phase, 20-30 in rain, and 2-10 in aerosols. The gas-phase and rain ratios are comparable to those predicted to result from isoprene oxidation. Pyruvic acid levels were similar in the eastern United States (during summer) and the Amazon Basin, suggesting that natural processes, particularly the photochemical oxidation of isoprene, could account for most of the pyruvic acid present in the atmosphere.

  18. Photolysis of formic acid at 355 nm

    NASA Astrophysics Data System (ADS)

    Martinez, Denhi; Bautista, Teonanacatl; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2015-05-01

    Formic acid is well known as a food additive and recently an application on fuel cell technology has emerged. In this work we have studied the dissociative ionization process by multiphoton absorption of formic acid molecules at 355nm wavelength photons, using TOF spectrometry in reflectron mode (R-TOF). Some of the most abundant ionic fragments produced are studied at different settings of the laser harmonic generator. The dependence of the products on these conditions is reported. This work was supported by CONACYT Project 165410 and PAPIIT IN102613 and IN101215.

  19. Formic acid fuel cells and catalysts

    DOEpatents

    Masel, Richard I.; Larsen, Robert; Ha, Su Yun

    2010-06-22

    An exemplary fuel cell of the invention includes a formic acid fuel solution in communication with an anode (12, 134), an oxidizer in communication with a cathode (16, 135) electrically linked to the anode, and an anode catalyst that includes Pd. An exemplary formic acid fuel cell membrane electrode assembly (130) includes a proton-conducting membrane (131) having opposing first (132) and second surfaces (133), a cathode catalyst on the second membrane surface, and an anode catalyst including Pd on the first surface.

  20. Car-parrinello molecular dynamics simulation of liquid formic acid.

    PubMed

    Bakó, I; Hutter, J; Pálinkás, G

    2006-02-16

    First-principles molecular dynamics has been used to investigate the structural, vibrational, and energetic properties of formic acid, formic acid-formate anion dimers, and liquid formic acid in a periodically repeated box with 32 formic acid molecules. We found that in liquid formic acid the hydrogen-bonded clusters mainly consist of linear branching chains. From our simulation, we got good agreement with the available structural and dynamical data. We also studied the proton transfer in the cis-formic acid-formate anion dimer, and we showed that this proton transfer does not have any potential barrier. The hydrogen bonding statistics as well as the mean lifetime of the hydrogen bonds are analyzed.

  1. Polymerization of formic acid under high pressure

    SciTech Connect

    Goncharov, A.F.; Manaa, M.R.; Zaug, J.M.; Gee, R.H.; Fried, L.E.; Montgomery, W.B.

    2010-07-19

    We report Raman, infrared, and x-ray diffraction (XRD) measurements, along with ab initio calculations on formic acid (FA) under pressure up to 50 GPa. We find an infinite chain Pna2{sub 1} structure to be a high-pressure phase at room temperature. Our data indicate the symmetrization and a partially covalent character of the intrachain hydrogen bonds above approximately 20 GPa. Raman spectra and XRD patterns indicate a loss of long-range order at pressures above 40 GPa, with a large hysteresis upon decompression. We attribute this behavior to a three-dimensional polymerization of FA.

  2. Evaluation of formic acid and propionic acid feed additives on environmental and cecal Salmonella Typhimurium in broilers

    USDA-ARS?s Scientific Manuscript database

    Three trials were performed to evaluate the effectiveness of formic acid and propionic acid on environmental and cecal recovery of Salmonella. Trial 1: Chicks (33/pen) were placed in one of 3 treatments with 8 reps, Trt A: 1 kg/ton formic acid, Trt B: 5 kg/ton formic acid, and Trt C: no formic acid....

  3. Hydrogen bond formations between pyrazine and formic acid and between pyrazine and trichloroacetic acid.

    PubMed

    Osaki, Tomoe; Suzuki, Yoshio; Hirokawa, Kenichiro; Shimada, Ryoichi

    2011-12-01

    The hydrogen bond formations between pyrazine and formic acids and between pyrazine and trichloroacetic acids were studied through observation of the Raman and infrared spectra for mixture of pyrazine and formic acid and also mixture of pyrazine and trichloroacetic acid at 77 K. It was observed that the mutual exclusion principle held for the Raman and infrared spectra of both mixtures, even for the spectra of the samples whose mixing mole ratio of acids was very low. This fact clearly indicates that the hydrogen bonded molecule does not exist in the form of formic acid-pyrazine or trichloroacetic acid-pyrazine whose geometry belongs to the Cs point group, but exists in the form of formic acid-pyrazine-formic acid or trichloroacetic acid-pyrazine-trichloroacetic acid belonging to the C(i) point group. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. The reaction of formic acid with RaneyTM copper

    NASA Astrophysics Data System (ADS)

    Callear, Samantha K.; Silverwood, Ian P.; Chutia, Arunabhiram; Catlow, C. Richard A.; Parker, Stewart F.

    2016-04-01

    The interaction of formic acid with RaneyTM Cu proves to be complex. Rather than the expected generation of a monolayer of bidentate formate, we find the formation of a Cu(II) compound. This process occurs by direct reaction of copper and formic acid; in contrast, previous methods are by solution reaction. This is a rare example of formic acid acting as an oxidant rather than, as more commonly found, a reductant. The combination of diffraction, spectroscopic and computational methods has allowed this unexpected process to be characterized.

  5. Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.

    ERIC Educational Resources Information Center

    Raw, C. J. G.; And Others

    1983-01-01

    Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)

  6. Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.

    ERIC Educational Resources Information Center

    Raw, C. J. G.; And Others

    1983-01-01

    Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)

  7. A prolific catalyst for dehydrogenation of neat formic acid

    PubMed Central

    Celaje, Jeff Joseph A.; Lu, Zhiyao; Kedzie, Elyse A.; Terrile, Nicholas J.; Lo, Jonathan N.; Williams, Travis J.

    2016-01-01

    Formic acid is a promising energy carrier for on-demand hydrogen generation. Because the reverse reaction is also feasible, formic acid is a form of stored hydrogen. Here we present a robust, reusable iridium catalyst that enables hydrogen gas release from neat formic acid. This catalysis works under mild conditions in the presence of air, is highly selective and affords millions of turnovers. While many catalysts exist for both formic acid dehydrogenation and carbon dioxide reduction, solutions to date on hydrogen gas release rely on volatile components that reduce the weight content of stored hydrogen and/or introduce fuel cell poisons. These are avoided here. The catalyst utilizes an interesting chemical mechanism, which is described on the basis of kinetic and synthetic experiments. PMID:27076111

  8. Aqueous-phase source of formic acid in clouds

    NASA Technical Reports Server (NTRS)

    Chameides, W. L.; Davis, D. D.

    1983-01-01

    The coupled gas- and aqueous-phase cloud chemistry of HCOOH were examined for controlling factors in the acidity of cloud and rainwater. Attention was given to the aqueous OH/HO2 system that yields an OH species that is highly reactive with other species, notably SO2 and the formaldehyde/formic acid complex. A numerical model was developed to simulate the cloud chemistry in the remote troposphere, with considerations given to CH4-CO-NO(x)-O3-H(x)O(y) system. It was determined that aqueous phase OH radicals can produce and destroy formic acid droplets in daylight conditions, as well as control formic acid levels in rainwater. It is sugested that the same types of reactions may be involved in the control of acetic acid and other organic acids.

  9. Reductive Leaching of Low-Grade Pyrolusite with Formic Acid

    NASA Astrophysics Data System (ADS)

    Lu, Youzhi; Ma, Huaju; Huang, Runjun; Yuan, Aiqun; Huang, Zengwei; Zhou, Zeguang

    2015-08-01

    The extraction of manganese from low-grade pyrolusite is investigated using formic acid as reductant in sulfuric acid medium. The effects of volumes of formic acid, concentration of sulfuric acid, liquid to solid ratio (L/S), leaching time, and temperature on leaching efficiency of manganese, iron, and aluminum are valuated with single-factor experiments. The results show that the leaching efficiency of manganese reached 90.08 pct with 80.70 pct of iron and 31.55 pct of aluminum under the optical conditions: 15 pct H2SO4(v/v) 60 ml, 4 ml formic acid, and 2 hours leaching time at 363 K (90 °C).

  10. Low contaminant formic acid fuel for direct liquid fuel cell

    DOEpatents

    Masel, Richard I.; Zhu, Yimin; Kahn, Zakia; Man, Malcolm

    2009-11-17

    A low contaminant formic acid fuel is especially suited toward use in a direct organic liquid fuel cell. A fuel of the invention provides high power output that is maintained for a substantial time and the fuel is substantially non-flammable. Specific contaminants and contaminant levels have been identified as being deleterious to the performance of a formic acid fuel in a fuel cell, and embodiments of the invention provide low contaminant fuels that have improved performance compared to known commercial bulk grade and commercial purified grade formic acid fuels. Preferred embodiment fuels (and fuel cells containing such fuels) including low levels of a combination of key contaminants, including acetic acid, methyl formate, and methanol.

  11. [Parenteral administration of formic acid in alternative medicine].

    PubMed

    Helmstädter, A

    2001-01-01

    Treatment of rheumatic and other diseases through immersion in an anthill is reported in German folk medicine. In the first half of the twentieth century, the physicians Eduard and Egon Krull (1842-1914 and 1879-1936, respectively) as well as Albrecht Reuter (1863-1937) recommended injections of diluted formic acid to treat tuberculosis, gout, arthritis, renal disorders and other complaints. Between 1930 and 1960, more than 15 different commercial preparations were marketed, and Egon Krull invented a drug series called "Myrmekan". Formic acid inhalations were recommended by Sigmund von Kapff (1864-1946) at a time when the acid was rarely used in homeopathy. In the 1950s, the injection of formic acid was regarded as one of the most important procedures in alternative medicine.

  12. Hydrogen Storage in the Carbon Dioxide - Formic Acid Cycle.

    PubMed

    Fink, Cornel; Montandon-Clerc, Mickael; Laurenczy, Gabor

    2015-01-01

    This year Mankind will release about 39 Gt carbon dioxide into the earth's atmosphere, where it acts as a greenhouse gas. The chemical transformation of carbon dioxide into useful products becomes increasingly important, as the CO(2) concentration in the atmosphere has reached 400 ppm. One approach to contribute to the decrease of this hazardous emission is to recycle CO(2), for example reducing it to formic acid. The hydrogenation of CO(2) can be achieved with a series of catalysts under basic and acidic conditions, in wide variety of solvents. To realize a hydrogen-based charge-discharge device ('hydrogen battery'), one also needs efficient catalysts for the reverse reaction, the dehydrogenation of formic acid. Despite of the fact that the overwhelming majority of these reactions are carried out using precious metals-based catalysts (mainly Ru), we review here developments for catalytic hydrogen evolution from formic acid with iron-based complexes.

  13. GLYCOLIC-FORMIC ACID FLOWSHEET FINAL REPORT FOR DOWNSELECTION DECISION

    SciTech Connect

    Lambert, D.; Pickenheim, B.; Stone, M.; Newell, J.; Best, D.

    2011-03-10

    Flowsheet testing was performed to develop the nitric-glycolic-formic acid flowsheet (referred to as the glycolic-formic flowsheet throughout the rest of the report) as an alternative to the nitric/formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be removed in the Sludge Receipt and Adjustment Tank (SRAT) with minimal hydrogen generation. All processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Forty-six runs were performed in total, including the baseline run and the melter feed preparation runs. Significant results are summarized. The baseline nitric/formic flowsheet run, using the SB6 simulant produced by Harrell was extremely difficult to process successfully under existing DWPF acceptance criteria with this simulant at the HM levels of noble metals. While nitrite was destroyed and mercury was removed to near the DWPF limit, the rheology of the SRAT and SME products were well above design basis and hydrogen generation far exceeded the DWPF SRAT limit. In addition, mixing during the SME cycle was very poor. In this sense, the nitric/glycolic/formic acid flowsheet represents a significant upgrade over the current flowsheet. Mercury was successfully removed with almost no hydrogen generation and the SRAT and SME products yield stresses were within process limits or previously processed ranges. The glycolic-formic flowsheet has a very wide processing window. Testing was completed from 100% to 200% of acid stoichiometry and using a glycolic-formic mixture from 40% to 100% glycolic acid. The testing met all processing requirements throughout these processing windows. This should allow processing at an acid stoichiometry of 100% and a glycolic-formic mixture of 80% glycolic acid with minimal hydrogen generation. It should also allow processing endpoints in the SRAT and SME at significantly higher

  14. Formic acid is a product of the alpha-oxidation of fatty acids by human skin fibroblasts: deficiency of formic acid production in peroxisome-deficient fibroblasts.

    PubMed Central

    Poulos, A; Sharp, P; Singh, H; Johnson, D W; Carey, W F; Easton, C

    1993-01-01

    Human skin fibroblasts in culture can oxidize beta-methyl fatty acids, such as phytanic acid and 3-methylhexadecanoic acid, to CO2 and water-soluble products. The latter are released largely into the culture medium. The major water-soluble product formed from [1-14C]phytanic and [1-14C]3-methylhexadecanoic acids is [14C]formic acid. As phytanic acid and 3-methylhexadecanoic acids contain beta-methyl groups and theoretically cannot be degraded by beta-oxidation, we postulate that formic acid is formed from fatty acids by alpha-oxidation. The marked reduction in formic acid production from beta-methyl fatty acids in peroxisome-deficient skin fibroblasts suggests that peroxisomes are involved in the generation of C1 units. PMID:8503880

  15. Enhanced formic acid oxidation on Cu-Pd nanoparticles

    NASA Astrophysics Data System (ADS)

    Dai, Lin; Zou, Shouzhong

    Developing catalysts with high activity and high resistance to surface poisoning remains a challenge in direct formic acid fuel cell research. In this work, copper-palladium nanoparticles were formed through a galvanic replacement process. After electrochemically selective dissolution of surface Cu, Pd-enriched Cu-Pd nanoparticles were formed. These particles exhibit much higher formic acid oxidation activities than that on pure Pd nanoparticles, and they are much more resistant to the surface poisoning. Possible mechanisms of catalytic activity enhancement are briefly discussed.

  16. Reactions between microhydrated superoxide anions and formic acid.

    PubMed

    Ryding, Mauritz Johan; Fernández, Israel; Uggerud, Einar

    2017-08-30

    Reactions between water clusters containing the superoxide anion, O2˙(-)(H2O)n (n = 0-4), and formic acid, HCO2H, were studied experimentally in vacuo and modelled using quantum chemical methods. Encounters between microhydrated superoxide and formic acid were found to result in a number of different reactions, including (a) proton transfer, (b) ligand exchange, (c) H2-elimination (affording microhydrated CO4˙(-)), and (d) dihydrogen transfer (affording H2O2 and microhydrated CO2˙(-)). The effect of reactant-ion hydration on reaction rates was investigated and the involved reaction mechanisms were elucidated.

  17. A Direct, Biomass-Based Synthesis of Benzoic Acid: Formic Acid-Mediated Deoxygenation of the Glucose-Derived Materials Quinic Acid and Shikimic Acid

    SciTech Connect

    Arceo, Elena; Ellman, Jonathan; Bergman, Robert

    2010-05-03

    An alternative biomass-based route to benzoic acid from the renewable starting materials quinic acid and shikimic acid is described. Benzoic acid is obtained selectively using a highly efficient, one-step formic acid-mediated deoxygenation method.

  18. GLYCOLIC-FORMIC ACID FLOWSHEET SLUDGE MATRIX STUDY

    SciTech Connect

    Lambert, D.; Koopman, D.

    2011-06-30

    Testing was completed to demonstrate the viability of the newly developed glycolic acid/formic acid flowsheet on processing in the Defense Waste Processing Facility's (DWPF) Chemical Process Cell (CPC). The Savannah River National Laboratory (SRNL) initiated a sludge matrix study to evaluate the impact of changing insoluble solid composition on the processing characteristics of slurries in DWPF. Four sludge simulants were prepared to cover two compositional ranges in the waste. The first was high iron/low aluminum versus low iron/high aluminum (referred to as HiFe or LoFe in this report). The second was high calcium-manganese/low nickel, chromium, and magnesium versus low calcium-manganese/high nickel, chromium, and magnesium (referred to as HiMn or LoMn in this report). These two options can be combined to form four distinct sludge compositions. The sludge matrix study called for testing each of these four simulants near the minimum acid required for nitrite destruction (100% acid stoichiometry) and at a second acid level that produced significant hydrogen by noble metal catalyzed decomposition of formic acid (150% acid stoichiometry). Four simulants were prepared based on the four possible combinations of the Al/Fe and Mn-Ca/Mg-Ni-Cr options. Preliminary simulant preparation work has already been documented. The four simulants were used for high and low acid testing. Eight planned experiments (GF26 to GF33) were completed to demonstrate the viability of the glycolic-formic flowsheet. Composition and physical property measurements were made on the SRAT product. Composition measurements were made on the condensate from the Mercury Water Wash Tank (MWWT), Formic Acid Vent Condenser (FAVC), ammonia scrubber and on SRAT samples pulled throughout the SRAT cycle. Updated values for formate loss and nitrite-tonitrate conversion were found that can be used in the acid calculations for future sludge matrix process simulations with the glycolic acid/formic acid flowsheet

  19. CO2 Hydrogenation to Formic Acid on Ni(110)

    SciTech Connect

    Peng, Guowen; Sibener, S. J.; Schatz, George C.; Mavrikakis, Manos

    2012-03-06

    Hydrogen (H) in the subsurface of transition-metal surfaces exhibits unique reactivity for heterogeneously catalyzed hydrogenation reactions. Here, we explore the potential of subsurface H for hydrogenating carbon dioxide (CO2) on Ni(110). The energetics of surface and subsurface H reacting with surface CO2 to form formate, carboxyl, and formic acid on Ni(110) is systematically studied using self-consistent, spin-polarized, periodic density functional theory (DFT-GGA-PW91) calculations. We show that on Ni(110), CO2 can be hydrogenated to formate by surface H. However, further hydrogenation of formate to formic acid by surface H is hindered by a larger activation energy barrier. The relative energetics of hydrogenation barriers is reversed for the carboxyl-mediated route to formic acid.We suggest that the energetics of subsurface H emerging to the surface is suitable for providing the extra energy needed to overcome the barrier to formate hydrogenation. CO2 hydrogenation to formic acid could take place on Ni(110) when subsurface H is available to react with CO2. Additional electronic-structure based dynamic calculations would be needed to elucidate the detailed reaction paths for these transformations.

  20. An Alternative Mechanism for the Dimerization of Formic Acid

    SciTech Connect

    Brinkman, Nicole R.; Tschumper, Gregory; Yan, Ge; Schaefer, Henry F.

    2003-11-01

    Gas-phase formic acid exists primarily as a cyclic dimer. The mechanism of dimerization has been traditionally considered to be a synchronous process; however, recent experimental findings suggest a possible alternative mechanism by which two formic acid monomers proceed through an acyclic dimer to the cyclic dimer in a stepwise process. To investigate this newly proposed process of dimerization in formic acid, density functional theory and second-order Moeller-Plesset perturbation theory (MP2) have been used to optimize cis and trans monomers of formic acid, the acyclic and cyclic dimers, and the acyclic and cyclic transition states between minima. Single-point energies of the trans monomer, dimer minima, and transition states at the MP2/TZ2P+diff optimized geometries were computed at the coupled-cluster level of theory including singles and doubles with perturbatively applied triple excitations [CCSD(T)] with an aug-cc-pVTZ basis set to obtain an accurate determination of energy barriers and dissociation energies. A counterpoise correction was performed to determine an estimate of the basis set superposition error in computing relative energies. The explicitly correlated MP2 method of Kutzelnigg and Klopper (MP2-R12) was used to provide an independent means for obtaining the MP2 one-particle limit. The cyclic minimum is predicted to be 6.3 kcal/mol more stable than the acyclic minimum, and the barrier to double proton transfer is 7.1 kcal/mol.

  1. Formic acid electrooxidation on Pd in acidic solutions studied by surface-enhanced infrared absorption spectroscopy.

    PubMed

    Miyake, Hiroto; Okada, Tatsuhiro; Samjeské, Gabor; Osawa, Masatoshi

    2008-07-07

    A mechanistic study of electrocatalytic oxidation of formic acid on Pd in sulfuric and perchloric acids is reported. Surface-enhanced infrared absorption spectroscopy in the attenuated total reflection mode (ATR-SEIRAS) shows the adsorption of CO, bridge-bonded formate, bicarbonate, and supporting anions on the electrode surface. Poisoning of the Pd surface by CO, formed by dehydration of formic acid, is very slow and scarcely affects formic acid oxidation. The anions are adsorbed more strongly in the order of (bi)sulfate > bicarbonate > perchlorate, among which the most strongly adsorbed (bi)sulfate considerably suppresses formic acid oxidation in the double layer region. The oxidation is suppressed also at higher potentials in both acids by the oxidation of the Pd surface. Adsorbed formate is detected only when formic acid oxidation is suppressed. The results show that formate is a short-lived reactive intermediate in formic acid oxidation and is hence detected when its decomposition yielding CO(2) is suppressed. The high electrocatalytic activity of Pd can be ascribed to the high tolerance to CO contamination and also high catalytic activity toward formate decomposition.

  2. Toxicity of formic acid against red imported fire ants, Solenopsis invicta Buren

    USDA-ARS?s Scientific Manuscript database

    BACKGROUND: Formic acid is a common defensive chemical of formicine ants. Ants often compete with other ants for resources. However, the toxicity of formic acid to any ant species has not been well understood. This study examined the toxicity of formic acid against the red imported fire ants, Sole...

  3. 76 FR 7106 - Food Additives Permitted in Feed and Drinking Water of Animals; Formic Acid

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-09

    ... Drinking Water of Animals; Formic Acid AGENCY: Food and Drug Administration, HHS. ACTION: Final rule... in feed and drinking water of animals to provide for the safe use of formic acid as an acidifying... safe use of formic acid as an acidifying agent at levels not to exceed 1.2 percent in swine feed. The...

  4. TES/Aura L2 Formic Acid (FOR) Nadir V6 (TL2FORN)

    Atmospheric Science Data Center

    2017-07-14

    TES/Aura L2 Formic Acid (FOR) Nadir (TL2FORN) News:  TES News Join ... L2 Platform:  TES/Aura L2 Formic Acid Spatial Coverage:  5.3 x 8.5 km nadir Spatial ... Access:  OPeNDAP Parameters:  Formic Acid Volume Mixing Ratio Precision Vertical Resolution Legacy:  ...

  5. TES/Aura L2 Formic Acid (FOR) Lite Nadir V6 (TL2FORLN)

    Atmospheric Science Data Center

    2017-07-20

    TES/Aura L2 Formic Acid (FOR) Lite Nadir (TL2FORLN) News:  TES News ... L2 Instrument:  TES/Aura L2 Formic Acid Spatial Coverage:  5.3 km nadir Spatial ... Access:  OPeNDAP Parameters:  Formic Acid Volume Mixing Ratio Vertical Resolution Precision Order ...

  6. Determination of gaseous formic acid and acetic acid by pulsed ultraviolet photoacoustic spectroscopy

    SciTech Connect

    Cvijin, P.V.; Gilmore, D.A.; Atkinson, G.H.

    1988-07-01

    The quantitative determination of gaseous formic acid and acetic acid by photoacoustic spectroscopy (PAS) using pulsed laser excitation in the ultraviolet is reported. Instrumentation utilizing continuously tunable laser excitation in the 220-nm wavelength region is used to record time-resolved PA signals from samples of each acid. Detection limits of 140 ppbv for formic acid and 120 ppbv for acetic acid in dry nitrogen at one atmosphere total pressure are attained. Considerable background signal originating from atmospheric oxygen is found to impose limitations on the detection sensitive with air samples.

  7. Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media

    PubMed Central

    Moret, Séverine; Dyson, Paul J.; Laurenczy, Gábor

    2014-01-01

    The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40 °C, 0.2 M formic acid can be obtained under 200 bar, however, in DMSO the same catalyst affords 1.9 M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes. PMID:24886955

  8. Kinetic study of formic acid oxidation on carbon supported Pd electrocatalyst

    NASA Astrophysics Data System (ADS)

    Wang, Yujiao; Wu, Bing; Gao, Ying; Tang, Yawen; Lu, Tianhong; Xing, Wei; Liu, Changpeng

    The oxidation of formic acid at the Pd/C catalyst electrode is a completely irreversible kinetic process with the reaction order of 1.0. The oxidation rate of formic acid is increased with increasing the concentration of formic acid and is decreased with increasing H + concentration. The apparent negative reaction order with respect to H + is about -0.18 or -0.04 in H 2SO 4 or HClO 4 solution respectively, because bisulfate anions would inhibit formic acid oxidation at some extent. The kinetic parameters, charge transfer coefficient and the diffusion coefficient of formic acid were obtained under the quasi steady-state conditions.

  9. Onboard Catalysis of Formic Acid for Hydrogen Fueled Vehicles

    NASA Astrophysics Data System (ADS)

    Karim, Altaf; Mamoor, Muhammad

    2015-03-01

    Metal hydrides are used as a medium of hydrogen storage in hydrogen powered vehicles. Such hydride materials cannot store hydrogen more than 10 wt%. The bottleneck in this issue is the reversible storage of hydrogen at ambient temperature and pressure. Alternatively formic acid is becoming more popular medium for the onboard hydrogen production for these vehicles. Its decomposition on metal surfaces and nanostructures is considered to be a potential method to produce CO-free hydrogen at near ambient temperatures. We applied Density Functional Theory (DFT) based Kinetic Monte Carlo (KMC) simulations as our tool to study the reaction kinetics of hydrogen production from formic acid on different catalytic surfaces and nano structures (Au, Pd, Rh, Pt). Our results show that nanostructures and artificially engineered bimetallic catalysts give higher rate of hydrogen production then their monometallic counter parts under various temperature and pressure conditions.

  10. Titanium dioxide nanotubes/polyhydroxyfullerene composites for formic acid photodegradation

    NASA Astrophysics Data System (ADS)

    Hamandi, Marwa; Berhault, Gilles; Dappozze, Frederic; Guillard, Chantal; Kochkar, Hafedh

    2017-08-01

    The influence of polyhydroxyfullerene (PHF) on the photocatalytic properties of calcined hydrogenotitanate nanotubes (HNT) were evaluated in the present study. PHF-HNT nanocomposites were first characterized by N2 adsorption-desorption measurements, X-ray diffraction, X-ray photoelectron, electron paramagnetic resonance and UV-vis diffuse reflectance spectroscopies, transmission electron microscopy, photoluminescence, and photocurrent experiments. Correlation was then established with the photocatalytic properties of PHF-HNT nanocomposites during the photodegradation of formic acid.

  11. Iron-catalyzed hydrogen production from formic acid.

    PubMed

    Boddien, Albert; Loges, Björn; Gärtner, Felix; Torborg, Christian; Fumino, Koichi; Junge, Henrik; Ludwig, Ralf; Beller, Matthias

    2010-07-07

    Hydrogen represents a clean energy source, which can be efficiently used in fuel cells generating electricity with water as the only byproduct. However, hydrogen generation from renewables under mild conditions and efficient hydrogen storage in a safe and reversible manner constitute important challenges. In this respect formic acid (HCO(2)H) represents a convenient hydrogen storage material, because it is one of the major products from biomass and can undergo selective decomposition to hydrogen and carbon dioxide in the presence of suitable catalysts. Here, the first light-driven iron-based catalytic system for hydrogen generation from formic acid is reported. By application of a catalyst formed in situ from inexpensive Fe(3)(CO)(12), 2,2':6'2''-terpyridine or 1,10-phenanthroline, and triphenylphosphine, hydrogen generation is possible under visible light irradiation and ambient temperature. Depending on the kind of N-ligands significant catalyst turnover numbers (>100) and turnover frequencies (up to 200 h(-1)) are observed, which are the highest known to date for nonprecious metal catalyzed hydrogen generation from formic acid. NMR, IR studies, and DFT calculations of iron complexes, which are formed under reaction conditions, confirm that PPh(3) plays an active role in the catalytic cycle and that N-ligands enhance the stability of the system. It is shown that the reaction mechanism includes iron hydride species which are generated exclusively under irradiation with visible light.

  12. Evaluation of clastogenicity of formic acid, acetic acid and lactic acid on cultured mammalian cells.

    PubMed

    Morita, T; Takeda, K; Okumura, K

    1990-03-01

    Using Chinese hamster ovary K1 cells, chromosomal aberration tests were carried out with formic acid, acetic acid and lactic acid, and the relationship between the pH of the medium and the clastogenic activity was examined. The medium used was Ham's F12 supplemented with 17 mM NaHCO3 and 10% fetal calf serum. All of these acids induced chromosomal aberrations at the initial pH of ca. 6.0 or below (about 10-14 mM of each acid) both with and without S9 mix. Exposure of cells to about pH 5.7 or below (about 12-16 mM of each acid) was found to be toxic. When the culture medium was first acidified with each of these acids and then neutralized to pH 6.4 or pH 7.2 with NaOH, no clastogenic activity was observed. Using F12 medium supplemented with 34 mM NaHCO3 as a buffer, no clastogenic activity was observed at doses up to 25 mM of these acids (initial pH 5.8-6.0). However, it was found that about 10% of the cells had aberrations at pH 5.7 or below (27.5-32.5 mM of each acid). Furthermore, when 30 mM HEPES was used as a buffer, chromosomal aberrations were not induced at doses up to 20 mM formic acid and acetic acid (initial pH 7.0-7.1), and at doses up to 30 mM lactic acid (initial pH 6.6). In the initial pH range of 6.4-6.7 (25-32.5 mM of each acid), chromosomal aberrations were observed. The above results show that these acids themselves are non-clastogenic, and the pseudo-positive reactions attributable to non-physiological pH could be eliminated by either neutralization of the treatment medium or enhancement of the buffering ability.

  13. Satellite evidence for a large source of formic acid from boreal and tropical forests

    NASA Astrophysics Data System (ADS)

    Stavrakou, T.; Müller, J.-F.; Peeters, J.; Razavi, A.; Clarisse, L.; Clerbaux, C.; Coheur, P.-F.; Hurtmans, D.; de Mazière, M.; Vigouroux, C.; Deutscher, N. M.; Griffith, D. W. T.; Jones, N.; Paton-Walsh, C.

    2012-01-01

    Formic acid contributes significantly to acid rain in remote environments. Direct sources of formic acid include human activities, biomass burning and plant leaves. Aside from these direct sources, sunlight-induced oxidation of non-methane hydrocarbons (largely of biogenic origin) is probably the largest source. However, model simulations substantially underpredict atmospheric formic acid levels, indicating that not all sources have been included in the models. Here, we use satellite measurements of formic acid concentrations to constrain model simulations of the global formic acid budget. According to our simulations, 100-120Tg of formic acid is produced annually, which is two to three times more than that estimated from known sources. We show that 90% of the formic acid produced is biogenic in origin, and largely sourced from tropical and boreal forests. We suggest that terpenoids--volatile organic compounds released by plants--are the predominant precursors. Model comparisons with independent observations of formic acid strengthen our conclusions, and provide indirect validation for the satellite measurements. Finally, we show that the larger formic acid emissions have a substantial impact on rainwater acidity, especially over boreal forests in the summer, where formic acid reduces pH by 0.25-0.5.

  14. Formic acid oxidation on platinum: a simple mechanistic study.

    PubMed

    Schwarz, Kathleen A; Sundararaman, Ravishankar; Moffat, Thomas P; Allison, Thomas C

    2015-08-28

    The oxidation of small organic acids on noble metal surfaces under electrocatalytic conditions is important for the operation of fuel cells and is of scientific interest, but the basic reaction mechanisms continue to be a matter of debate. Formic acid oxidation on platinum is one of the simplest of these reactions, yet even this model system remains poorly understood. Historically, proposed mechanisms for the oxidation of formic acid involve the acid molecule as a reactant, but recent studies suggest that the formate anion is the reactant. Ab initio studies of this reaction do not address formate as a possible reactant, likely because of the difficulty of calculating a charged species near a charged solvated surface under potential control. Using the recently-developed joint density functional theory (JDFT) framework for electrochemistry, we perform ab initio calculations on a Pt(111) surface to explore this reaction and help resolve the debate. We find that when a formate anion approaches the platinum surface at typical operating voltages, with H pointing towards the surface, it reacts to form CO2 and adsorbed H with no barrier on a clean Pt surface. This mechanism leads to a reaction rate proportional to formate concentration and number of available platinum sites. Additionally, high coverages of adsorbates lead to large reaction barriers, and consequently, we expect the availability of metal sites to limit the experimentally observed reaction rate.

  15. Direct formic acid microfluidic fuel cell design and performance evolution

    NASA Astrophysics Data System (ADS)

    Moreno-Zuria, A.; Dector, A.; Cuevas-Muñiz, F. M.; Esquivel, J. P.; Sabaté, N.; Ledesma-García, J.; Arriaga, L. G.; Chávez-Ramírez, A. U.

    2014-12-01

    This work reports the evolution of design, fabrication and testing of direct formic acid microfluidic fuel cells (DFAμFFC), the architecture and channel dimensions are miniaturized from a thousand to few cents of micrometers. Three generations of DFAμFFCs are presented, from the initial Y-shape configuration made by a hot pressing technique; evolving into a novel miniaturized fuel cell based on microfabrication technology using SU-8 photoresist as core material; to the last air-breathing μFFC with enhanced performance and built with low cost materials and processes. The three devices were evaluated in acidic media in the presence of formic acid as fuel and oxygen/air as oxidant. Commercial Pt/C (30 wt. % E-TEK) and Pd/C XC-72 (20 wt. %, E-TEK) were used as cathode and anode electrodes respectively. The air-breathing μFFC generation, delivered up to 27.3 mW cm-2 for at least 30 min, which is a competitive power density value at the lowest fuel flow of 200 μL min-1 reported to date.

  16. Significant enhancement of formic acid oxidation using rhodium nanostructures.

    PubMed

    Balan, Beena K; Sathe, Bhaskar R

    2012-12-01

    The electrocatalytic activity of as-synthesized shape selective Rh nanostructures has been demonstrated using cyclic voltammetry, revealing unique shape-dependant performance towards HCOOH oxidation. Interestingly, the enhancement factor (R) for different shapes of Rh with respect to that of commercial Rh towards formic acid oxidation ranges up to 20,000% for cubes as compared to 17,500% for pyramids and 11,000% for hexagons respectively. Mechanistic pathway for comparatively better sensitivity of cubes as compared to other shapes has been correlated with the results of X-ray diffraction.

  17. TES/Aura L2 Formic Acid (FOR) Nadir V6 (TL2FORNS)

    Atmospheric Science Data Center

    2017-07-14

    TES/Aura L2 Formic Acid (FOR) Nadir (TL2FORNS) News:  TES News Join ... L2 Platform:  TES/Aura L2 Formic Acid Spatial Coverage:  5.3 x 8.5 km nadir Spatial ... Access:  OPeNDAP Parameters:  Formic Acid Volume Mixing Ratio Precision Vertical Resolution Legacy:  ...

  18. Hydrogenation of CO2 to formic acid promoted by a diamine-functionalized ionic liquid.

    PubMed

    Zhang, Zhaofu; Hu, Suqin; Song, Jinliang; Li, Wenjing; Yang, Guanying; Han, Buxing

    2009-01-01

    Amines to an end: The basic diamine-functionalized ionic liquid 1,3-di(N,N-dimethylaminoethyl)-2-methylimidazolium trifluoromethanesulfonate was prepared and used in the hydrogenation of CO(2) to formic acid. One mole of the ionic liquid coordinates two moles of formic acid to promote the reaction. Both the ionic liquid and catalyst can be reused directly after their separation from the formic acid produced.

  19. Global formic acid measurements from space: The importance of biomass burning emissions

    NASA Astrophysics Data System (ADS)

    Chaliyakunnel, S.; Millet, D. B.; Wells, K. C.; Cady-Pereira, K. E.; Shephard, M. W.

    2013-12-01

    Formic acid is one of the most abundant carboxylic acids in the atmosphere, and a dominant source of acidity in the global troposphere. In this work, we present the first global retrievals of formic acid from the Tropospheric Emission Spectrometer (TES) satellite instrument. We apply the GEOS-Chem Chemical Transport Model (CTM) and an ensemble of airborne and ground observations to evaluate the TES data, and find that the formic acid distributions derived from TES are consistent with in situ measurements. The space-based formic acid data reveal a severe model underestimate that manifests globally; however, the simulated and observed concentrations are spatially well-correlated. The discrepancy between GEOS-Chem and TES is most prominent over tropical biomass burning regions, indicating a major missing source of organic acids from fires. We use the TES data to derive new top-down constraints on the pyrogenic source of formic acid to the atmosphere.

  20. New Theoretical Insight into the Interactions and Properties of Formic Acid: Development of a Quantum-Based Pair Potential for Formic Acid.

    SciTech Connect

    Roszak, S; Gee, R; Balasubramanian, K; Fried, L

    2005-08-08

    We performed ab initio quantum chemical studies for the development of intra and intermolecular interaction potentials for formic acid for use in molecular dynamics simulations of formic acid molecular crystal. The formic acid structures considered in the ab initio studies include both the cis and trans monomers which are the conformers that have been postulated as part of chains constituting liquid and crystal phases under extreme conditions. Although the cis to trans transformation is not energetically favored, the trans isomer was found as a component of stable gas-phase species. Our decomposition scheme for the interaction energy indicates that the hydrogen bonded complexes are dominated by the Hartree-Fock forces while parallel clusters are stabilized by the electron correlation energy. The calculated three-body and higher interactions are found to be negligible, thus rationalizing the development of an atom-atom pair potential for formic acid based on high-level ab initio calculations of small formic acid clusters. Here we present an atom-atom pair potential that includes both intra- and inter-molecular degrees of freedom for formic acid. The newly developed pair potential is used to examine formic acid in the condensed phase via molecular dynamics simulations. The isothermal compression under hydrostatic pressure obtained from molecular dynamics simulations is in good agreement with experiment. Further, the calculated equilibrium melting temperature is found to be in good agreement with experiment.

  1. On the conformational memory in the photodissociation of formic acid.

    PubMed

    Martínez-Núñez, E; Vazquez, S A; Borges, I; Rocha, A B; Estévez, C M; Castillo, J F; Aoiz, F J

    2005-03-31

    The photodissociation of formic acid at 248 and 193 nm was investigated by classical trajectory and RRKM calculations using an interpolated potential energy surface, iteratively constructed using the B3LYP/aug-cc-pVDZ level of calculation. Several sampling schemes in the ground electronic state were employed to explore the possibility of conformational memory in formic acid. The CO/CO2 branching ratios obtained from trajectories initiated at the cis and at the trans conformers are almost identical to each other and in very good accordance with the RRKM results. In addition, when a specific initial excitation that simulates more rigorously the internal conversion process is used, the calculated branching ratio does not vary with respect to those obtained from cis and trans initializations. This result is at odds with the idea of conformational memory in the ground state proposed recently for the interpretation of the experimental results. It was also found that the calculated CO vibrational distributions after dissociation of the parent molecule at 248 nm are in agreement with the experimental available data.

  2. Formic acid and acetic acid measurements during the Southern California Air Quality Study

    NASA Astrophysics Data System (ADS)

    Grosjean, Daniel

    As part of the Southern California Air Quality Study (SCAQS), ambient levels of gas phase formic acid and acetic acid have been measured at four locations: a 'control' site (San Nicholas Island), a source-dominated coastal site (Long Beach) and two inland smog receptor sites (Claremont and Palm Springs). Samples were collected on alkaline traps and were analyzed by size exclusion liquid chromatography with ultraviolet detection. Levels of gas phase formic acid (up to 19 ppb) and acetic acid (up to 17 ppb) exhibited diurnal (frequent night-time maxima), spatial and seasonal variations. During summer smog episodes, concentrations increased from 0.6 ppb at the 'control' site to up to 13-19 ppb at the inland smog receptor sites reflecting primary emissions and in situ formation during transport inland. The acetic acid/formic acid (A/F) ratio decreased from coastal to inland sites. At the coastal site levels of both acids and the A/F ratio were substantially higher during the fall than during the summer.

  3. Investigation of secondary formation of formic acid: urban environment vs. oil and gas producing region

    NASA Astrophysics Data System (ADS)

    Yuan, B.; Veres, P. R.; Warneke, C.; Roberts, J. M.; Gilman, J. B.; Koss, A.; Edwards, P. M.; Graus, M.; Kuster, W. C.; Li, S.-M.; Wild, R. J.; Brown, S. S.; Dubé, W. P.; Lerner, B. M.; Williams, E. J.; Johnson, J. E.; Quinn, P. K.; Bates, T. S.; Lefer, B.; Hayes, P. L.; Jimenez, J. L.; Weber, R. J.; Zamora, R.; Ervens, B.; Millet, D. B.; Rappenglück, B.; de Gouw, J. A.

    2014-09-01

    Formic acid (HCOOH) is one of the most abundant carboxylic acids in the atmosphere. However, current photochemical models cannot fully explain observed concentrations and in particular secondary formation of formic acid across various environments. In this work, formic acid measurements made at an urban receptor site in June-July of 2010 during CalNex and a site in an oil and gas producing region in January-February of 2013 during UBWOS 2013 will be discussed. Although the VOC compositions differed dramatically at the two sites, measured formic acid concentrations were comparable: 2.3 ± 1.3 ppb in UBWOS 2013 and 2.0 ± 1.0 ppb in CalNex. We determine that concentrations of formic acid at both sites were dominated by secondary formation (> 8%). A constrained box model using the Master Chemical Mechanism (MCM v3.2) underestimates the measured formic acid concentrations drastically at both sites (by a factor of > 10). Inclusion of recent findings on additional precursors and formation pathways of formic acid in the box model increases modeled formic acid concentrations for UBWOS 2013 and CalNex by a factor of 6.4 and 4.5, respectively. A comparison of measured and modeled HCOOH/acetone ratios is used to evaluate the model performance for formic acid. We conclude that the modified chemical mechanism can explain 21 and 47% of secondary formation of formic acid in UBWOS 2013 and CalNex, respectively. The contributions from aqueous reactions in aerosol and heterogeneous reactions on aerosol surface to formic acid are estimated to be -7 and 0-6% in UBWOS 2013 and CalNex, respectively. We observe that air-snow exchange processes and morning fog events may also contribute to ambient formic acid concentrations during UBWOS 2013 (∼20% in total). In total, 50-57% in UBWOS 2013 and 48-53% in CalNex of secondary formation of formic acid remains unexplained. More work on formic acid formation pathways is needed to reduce the uncertainties in the sources and budget of formic

  4. Anchoring the gas-phase acidity scale: From formic acid to methanethiol

    NASA Astrophysics Data System (ADS)

    Eyet, Nicole; Villano, Stephanie M.; Bierbaum, Veronica M.

    2009-06-01

    We have measured the gas-phase acidities of nine compounds: formic acid, acetic acid, 1,3-propanedithiol, 2-methyl-2-propanethiol, 3-methyl-1-butanethiol, 2-propanethiol, 1-propanethiol, ethanethiol, and methanethiol, with acidities ranging from 338.6 to 351.1 kcal mol-1 using proton transfer kinetics and the resulting equilibrium constants. These acids were anchored to the well-known acidity of hydrogen sulfide; the measured acidities are in good agreement with previous experimental values, but error bars are significantly reduced. The gas-phase acidity of 3-methyl-1-butanethiol was determined to be 347.1 (5) kcal mol-1; there were no previous measurements of this value. Entropies of deprotonation were calculated and enthalpies of deprotonation were determined.

  5. Elucidation of noble metal/formic acid chemistry during DWPF feed preparation

    SciTech Connect

    Landon, L.F.

    1991-01-01

    Eleven reports are included: evaluation of noble metal compounds as catalysts for aerobic decomposition of formic acid; reaction of NaNO[sub 3] and NaNO[sub 2] with formic acid under argon; effects of Ru, Rh, Pd chlorides on formic acid decomposition in presence of IDMS (pH=11.0) sludge; effects of additives on catalysts on decomposition of formic acid to hydrogen; Rh-catalyzed decomposition of formic acid; the question of whether this decomposition can be heterogeneous catalysis; inhibition of this reaction by additives; nitrilotriacetic acid inhibitor; uses of gelatin and other water soluble polymers to control flocculation rate; comparison of catalytic activities of Rh, Ru, Pd in Purex and HM sludges; experiments on homogeneous vs heterogeneous nature of Rh catalyst. Figs, refs, tabs.

  6. Elucidation of noble metal/formic acid chemistry during DWPF feed preparation. Revision 1

    SciTech Connect

    Landon, L.F.

    1991-12-31

    Eleven reports are included: evaluation of noble metal compounds as catalysts for aerobic decomposition of formic acid; reaction of NaNO{sub 3} and NaNO{sub 2} with formic acid under argon; effects of Ru, Rh, Pd chlorides on formic acid decomposition in presence of IDMS (pH=11.0) sludge; effects of additives on catalysts on decomposition of formic acid to hydrogen; Rh-catalyzed decomposition of formic acid; the question of whether this decomposition can be heterogeneous catalysis; inhibition of this reaction by additives; nitrilotriacetic acid inhibitor; uses of gelatin and other water soluble polymers to control flocculation rate; comparison of catalytic activities of Rh, Ru, Pd in Purex and HM sludges; experiments on homogeneous vs heterogeneous nature of Rh catalyst. Figs, refs, tabs.

  7. Study on the structure and properties of wool keratin regenerated from formic acid.

    PubMed

    Aluigi, A; Zoccola, M; Vineis, C; Tonin, C; Ferrero, F; Canetti, M

    2007-08-01

    Structural characteristics of keratin regenerated from water (KW) and from formic (KF) acid solutions were compared. Amino acid composition and molecular weight distribution of KW and KF samples were studied by high performance liquid chromatography (HPLC) and SDS-PAGE electrophoresis. Turbidity measurement showed that keratin dissolved in formic acid forms transparent and stable solutions and no flocculation occurs. In addition, because of its good solvation properties, studied by viscosity measurements, formic acid can be used as a co-solvent to prepare keratin-based blend solutions. Structural studies carried out by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and near infrared (NIR) suggest that formic acid stabilizes the beta-sheet structure. Thermogravimetric analysis (TGA) reveals a higher thermal stability of keratin regenerated from formic acid with respect to keratin regenerated from water.

  8. Formic acid measurements from space: Retrieval strategy, evaluation, and initial constraints on primary and secondary sources

    NASA Astrophysics Data System (ADS)

    Millet, D. B.; Chaliyakunnel, S.; Wells, K. C.; Cady-Pereira, K. E.; Shephard, M. W.; Luo, M.; Paulot, F.

    2012-12-01

    Formic acid is a major contributor to acidity in the global atmosphere, and recent work suggests that its sources are significantly underestimated. New space-borne measurements from the Tropospheric Emission Spectrometer (TES), onboard EOS Aura, offer valuable global data for investigating this issue, and for quantifying primary and secondary formic acid sources to the atmosphere. In this presentation, we describe the TES formic acid retrieval strategy along with a series of sensitivity studies to test its reliability. We present initial global results showing the seasonal and spatial distribution of formic acid in the lower troposphere, and apply a 3D chemical transport model (GEOS-Chem) to i) evaluate the TES retrievals against a collection of airborne and ground-based observations, and ii) assess what constraints the satellite data can provide on the budget of atmospheric formic acid.

  9. Hydrogen storage and delivery: the carbon dioxide - formic acid couple.

    PubMed

    Laurenczy, Gábor

    2011-01-01

    Carbon dioxide and the carbonates, the available natural C1 sources, can be easily hydrogenated into formic acid and formates in water; the rate of this reduction strongly depends on the pH of the solution. This reaction is catalysed by ruthenium(II) pre-catalyst complexes with a large variety of water-soluble phosphine ligands; high conversions and turnover numbers have been realised. Although ruthenium(II) is predominant in these reactions, the iron(II) - tris[(2-diphenylphosphino)-ethyl]phosphine (PP3) complex is also active, showing a new perspective to use abundant and inexpensive iron-based compounds in the CO2 reduction. In the catalytic hydrogenation cycles the in situ formed metal hydride complexes play a key role, their structures with several other intermediates have been proven by multinuclear NMR spectroscopy. In the other hand safe and convenient hydrogen storage and supply is the fundamental question for the further development of the hydrogen economy; and carbon dioxide has been recognised to be a viable H2 vector. Formic acid--containing 4.4 weight % of H2, that is 53 g hydrogen per litre--is suitable for H2 storage; we have shown that in aqueous solutions it can be selectively decomposed into CO-free (CO < 10 ppm) CO2 and H2. The reaction takes place under mild experimental conditions and it is able to generate high pressure H2 (up to 600 bar). The cleavage of HCOOH is catalysed by several hydrophilic Ru(II) phosphine complexes (meta-trisulfonated triphenylphosphine, mTPPTS, being the most efficient one), either in homogeneous systems or as immobilised catalysts. We have also shown that the iron(II)--hydrido tris[(2-diphenylphosphino)ethyl]phosphine complex catalyses with an exceptionally high rate and efficiency (turnover frequency, TOF = 9425 h(-1)mol(-1); turnover number, TON = 92400) the formic acid cleavage, in environmentally friendly propylene carbonate solution, opening the way to use cheap, non-noble metal based catalysts for this

  10. Investigation of secondary formation of formic acid: urban environment vs. oil and gas producing region

    NASA Astrophysics Data System (ADS)

    Yuan, B.; Veres, P. R.; Warneke, C.; Roberts, J. M.; Gilman, J. B.; Koss, A.; Edwards, P. M.; Graus, M.; Kuster, W. C.; Li, S.-M.; Wild, R. J.; Brown, S. S.; Dubé, W. P.; Lerner, B. M.; Williams, E. J.; Johnson, J. E.; Quinn, P. K.; Bates, T. S.; Lefer, B.; Hayes, P. L.; Jimenez, J. L.; Weber, R. J.; Zamora, R.; Ervens, B.; Millet, D. B.; Rappenglück, B.; de Gouw, J. A.

    2015-02-01

    Formic acid (HCOOH) is one of the most abundant carboxylic acids in the atmosphere. However, current photochemical models cannot fully explain observed concentrations and in particular secondary formation of formic acid across various environments. In this work, formic acid measurements made at an urban receptor site (Pasadena) in June-July 2010 during CalNex (California Research at the Nexus of Air Quality and Climate Change) and a site in an oil and gas producing region (Uintah Basin) in January-February 2013 during UBWOS 2013 (Uintah Basin Winter Ozone Studies) will be discussed. Although the VOC (volatile organic compounds) compositions differed dramatically at the two sites, measured formic acid concentrations were comparable: 2.3 ± 1.3 in UBWOS 2013 and 2.0 ± 1.0 ppb in CalNex. We determine that concentrations of formic acid at both sites were dominated by secondary formation (> 99%). A constrained box model using the Master Chemical Mechanism (MCM v3.2) underestimates the measured formic acid concentrations drastically at both sites (by a factor of > 10). Compared to the original MCM model that includes only ozonolysis of unsaturated organic compounds and OH oxidation of acetylene, when we updated yields of ozonolysis of alkenes and included OH oxidation of isoprene, vinyl alcohol chemistry, reaction of formaldehyde with HO2, oxidation of aromatics, and reaction of CH3O2 with OH, the model predictions for formic acid were improved by a factor of 6.4 in UBWOS 2013 and 4.5 in CalNex, respectively. A comparison of measured and modeled HCOOH/acetone ratios is used to evaluate the model performance for formic acid. We conclude that the modified chemical mechanism can explain 19 and 45% of secondary formation of formic acid in UBWOS 2013 and CalNex, respectively. The contributions from aqueous reactions in aerosol and heterogeneous reactions on aerosol surface to formic acid are estimated to be 0-6 and 0-5% in UBWOS 2013 and CalNex, respectively. We observe that

  11. Structure for the Propiolic Acid - Formic Acid Complex from Microwave Spectra for Multiple Isotopologues

    NASA Astrophysics Data System (ADS)

    Kukolich, Stephen G.; Mitchell, Erik G.; Carey, Spencer J.; Sun, Ming; Sargus, Bryan M.

    2013-06-01

    New microwave spectra were measured to obtain rotational constants and centrifugal distortion constants for the DCCCOOH---HOOCH and HCCCOOD---DOOCH isotopologues. Transitions were measured in the 4.9-15.4 GHz range, providing accurate rotational constants which, combined with previous rotational constants allowed an improved structural fit for the propiolic acid - formic acid complex. The new structural fit yields orientations for both the propiolic and formic acid monomers in the complex and more accurate structural parameters describing the hydrogen bonding. The structure is planar, with a positive inertial defect of Δ = 1.33 amu Å^2.The experimental structure exhibits a greater asymmetry for the two hydrogen bond lengths than was obtained from the ab initio mp2 calculations.The average of the two hydrogen bond lengths is R(exp) = 1.76 Å, in good agreement with R(theory) = 1.72 Å.

  12. Importance of acid-base equilibrium in electrocatalytic oxidation of formic acid on platinum.

    PubMed

    Joo, Jiyong; Uchida, Taro; Cuesta, Angel; Koper, Marc T M; Osawa, Masatoshi

    2013-07-10

    Electro-oxidation of formic acid on Pt in acid is one of the most fundamental model reactions in electrocatalysis. However, its reaction mechanism is still a matter of strong debate. Two different mechanisms, bridge-bonded adsorbed formate mechanism and direct HCOOH oxidation mechanism, have been proposed by assuming a priori that formic acid is the major reactant. Through systematic examination of the reaction over a wide pH range (0-12) by cyclic voltammetry and surface-enhanced infrared spectroscopy, we show that the formate ion is the major reactant over the whole pH range examined, even in strong acid. The performance of the reaction is maximal at a pH close to the pKa of formic acid. The experimental results are reasonably explained by a new mechanism in which formate ion is directly oxidized via a weakly adsorbed formate precursor. The reaction serves as a generic example illustrating the importance of pH variation in catalytic proton-coupled electron-transfer reactions.

  13. Dimers of formic acid: Structures, stability, and double proton transfer

    NASA Astrophysics Data System (ADS)

    Farfán, Paola; Echeverri, Andrea; Diaz, Estefanía; Tapia, Juan David; Gómez, Sara; Restrepo, Albeiro

    2017-07-01

    A stochastic search of the potential energy surface for the formic acid dimers results in 21 well-defined minima. A number of structures are reported here for the first time, others have already been experimentally detected or computationally predicted. Four types of different hydrogen bonds (HBs) are at play stabilizing the clusters: primary C=O⋯ H—O and H—O⋯ H—O and secondary C=O⋯ H—C and H—O⋯ H—C HBs corresponding to well-characterized bonding paths are identified. A novel C=O⋯ C stabilizing interaction is also reported. The double proton transfer reaction is calculated to occur in a synchronous fashion, with an energy barrier smaller than the energy needed to break up the dimers.

  14. Nuclear dynamics and phase polymorphism in solid formic acid.

    PubMed

    Krzystyniak, Maciej; Drużbicki, Kacper; Romanelli, Giovanni; Gutmann, Matthias J; Rudić, Svemir; Imberti, Silvia; Fernandez-Alonso, Felix

    2017-03-29

    We apply a unique sequence of structural and dynamical neutron-scattering techniques, augmented with density-functional electronic-structure calculations, to establish the degree of polymorphism in an archetypal hydrogen-bonded system - crystalline formic acid. Using this combination of experimental and theoretical techniques, the hypothesis by Zelsmann on the coexistence of the β1 and β2 phases above 220 K is tested. Contrary to the postulated scenario of proton-transfer-driven phase coexistence, the emerging picture is one of a quantitatively different structural change over this temperature range, whereby the loosening of crystal packing promotes temperature-induced shearing of the hydrogen-bonded chains. The presented work, therefore, solves a fifty-year-old puzzle and provides a suitable framework for the use neutron-Compton-scattering techniques in the exploration of phase polymorphism in condensed matter.

  15. Dimers of formic acid: Structures, stability, and double proton transfer.

    PubMed

    Farfán, Paola; Echeverri, Andrea; Diaz, Estefanía; Tapia, Juan David; Gómez, Sara; Restrepo, Albeiro

    2017-07-28

    A stochastic search of the potential energy surface for the formic acid dimers results in 21 well-defined minima. A number of structures are reported here for the first time, others have already been experimentally detected or computationally predicted. Four types of different hydrogen bonds (HBs) are at play stabilizing the clusters: primary C=O⋯ H-O and H-O⋯ H-O and secondary C=O⋯ H-C and H-O⋯ H-C HBs corresponding to well-characterized bonding paths are identified. A novel C=O⋯ C stabilizing interaction is also reported. The double proton transfer reaction is calculated to occur in a synchronous fashion, with an energy barrier smaller than the energy needed to break up the dimers.

  16. Proton transfer in methyleneimine complexed with formic acid

    NASA Astrophysics Data System (ADS)

    Peeters, D.

    1994-06-01

    The hydrogen-bonded complexes and the proton transfer process between methyleneimine and formic acid have been investigated from a theoretical viewpoint. The structures are fully optimized at the RHF 6-31G level and the corresponding force constant matrix obtained. Complementary computation at 6-31G* and 6-31G** levels as well as MP2 calculations were performed. The 1 : 1 system presents a single-well potential energy, but a double-well potential energy may be induced by a solvent effect. This solvent-induced effect may be obtained either by adding one extra molecule leading to trimolecular complexes or by immersing the bimolecular complex in the reaction field of a dielectric continuum. This study shows that slightly polar solvents (ɛ ⩾ 2.5) are sufficient to induce the proton transfer.

  17. Reduction reaction analysis of nanoparticle copper oxide for copper direct bonding using formic acid

    NASA Astrophysics Data System (ADS)

    Fujino, Masahisa; Akaike, Masatake; Matsuoka, Naoya; Suga, Tadatomo

    2017-04-01

    Copper direct bonding is required for electronics devices, especially power devices, and copper direct bonding using formic acid is expected to lower the bonding temperature. In this research, we analyzed the reduction reaction of copper oxide using formic acid with a Pt catalyst by electron spin resonance analysis and thermal gravimetry analysis. It was found that formic acid was decomposed and radicals were generated under 200 °C. The amount of radicals generated was increased by adding the Pt catalyst. Because of these radicals, both copper(I) oxide and copper(II) oxide start to be decomposed below 200 °C, and the reduction of copper oxide is accelerated by reactants such as H2 and CO from the decomposition of formic acid above 200 °C. The Pt catalyst also accelerates the reaction of copper oxide reduction. Herewith, it is considered that the copper surface can be controlled more precisely by using formic acid to induce direct bonding.

  18. On the origin of reactive Pd catalysts for an electrooxidation of formic acid.

    PubMed

    Jeon, Hongrae; Uhm, Sunghyun; Jeong, Beomgyun; Lee, Jaeyoung

    2011-04-07

    We investigated the origin of the reactive surface of Pd catalysts during the electrocatalytic oxidation of formic acid. XPS analysis was the primary tool adapted to characterize the surface changes in Pd catalysts arising from interactions with formic acid. Pd catalysts showed fast deactivation, though their activity could be simply recovered by applying a reduction potential at which hydrogen evolution reaction can occur. XPS analysis revealed that the surface of Pd catalysts is significantly affected by interaction with formic acid, thus confirming that the surface coverage of oxygen species plays an important role in formic acid electrooxidation on the Pd catalysts. At the same time, mass transfer of formic acid also has an effect on the deactivation of Pd catalysts.

  19. Influence of Sodium Carbonate on Decomposition of Formic Acid by Discharge inside Bubble in Water

    NASA Astrophysics Data System (ADS)

    Iwabuchi, Masashi; Takahashi, Katsuyuki; Takaki, Koichi; Satta, Naoya

    2015-09-01

    An influence of sodium carbonate on decomposition of formic acid by discharge inside bubble in water was investigated. Oxygen or argon gases were injected into the water through a vertically positioned glass tube, in which the high-voltage wire electrode was placed to generate plasmas at low applied voltage. The concentration of formic acid was determined by ion chromatography. In the case of addition of sodium carbonate, the pH value increased with decomposition of the formic acid. In the case of oxygen injection, the increase of pH value contributed to improve an efficiency of the formic acid decomposition because the reaction rate of ozone and formic acid increased with increasing pH value. In the case of argon injection, the decomposition rate was not affected by the pH value owing to the high rate constants for loss of hydroxyl radicals.

  20. Controlling the equilibrium of formic acid with hydrogen and carbon dioxide using ionic liquid.

    PubMed

    Yasaka, Yoshiro; Wakai, Chihiro; Matubayasi, Nobuyuki; Nakahara, Masaru

    2010-03-18

    The equilibrium for the reversible decomposition of formic acid into carbon dioxide and hydrogen is studied in the ionic liquid (IL) 1,3-dipropyl-2-methylimidazolium formate. The equilibrium is strongly favored to the formic acid side because of the strong solvation of formic acid in the IL through the strong Coulombic solute-solvent interactions. The comparison of the equilibrium constants in the IL and water has shown that the pressures required to transform hydrogen and carbon dioxide into formic acid can be reduced by a factor of approximately 100 by using the IL instead of water. The hydrogen transformation in such mild conditions can be a chemical basis for the hydrogen storage and transportation using formic acid.

  1. Laboratory Studies on the Formation of Formic Acid (HCOOH) in Interstellar and Cometary Ices

    NASA Astrophysics Data System (ADS)

    Bennett, Chris J.; Hama, Tetsuya; Kim, Yong Seol; Kawasaki, Masahiro; Kaiser, Ralf I.

    2011-01-01

    Mixtures of water (H2O) and carbon monoxide (CO) ices were irradiated at 10 K with energetic electrons to simulate the energy transfer processes that occur in the track of galactic cosmic-ray particles penetrating interstellar ices. We identified formic acid (HCOOH) through new absorption bands in the infrared spectra at 1690 and 1224 cm-1 (5.92 and 8.17 μm, respectively). During the subsequent warm-up of the irradiated samples, formic acid is evident from the mass spectrometer signal at the mass-to-charge ratio, m/z = 46 (HCOOH+) as the ice sublimates. The detection of formic acid was confirmed using isotopically labeled water-d2 with carbon monoxide, leading to formic acid-d2 (DCOOD). The temporal fits of the reactants, reaction intermediates, and products elucidate two reaction pathways to formic acid in carbon monoxide-water ices. The reaction is induced by unimolecular decomposition of water forming atomic hydrogen (H) and the hydroxyl radical (OH). The dominating pathway to formic acid (HCOOH) was found to involve addition of suprathermal hydrogen atoms to carbon monoxide forming the formyl radical (HCO); the latter recombined with neighboring hydroxyl radicals to yield formic acid (HCOOH). To a lesser extent, hydroxyl radicals react with carbon monoxide to yield the hydroxyformyl radical (HOCO), which recombined with atomic hydrogen to produce formic acid. Similar processes are expected to produce formic acid within interstellar ices, cometary ices, and icy satellites, thus providing alternative processes for the generation of formic acid whose abundance in hot cores such as Sgr-B2 cannot be accounted for solely by gas-phase chemistry.

  2. LABORATORY STUDIES ON THE FORMATION OF FORMIC ACID (HCOOH) IN INTERSTELLAR AND COMETARY ICES

    SciTech Connect

    Bennett, Chris J.; Kim, Yong Seol; Kaiser, Ralf I.; Hama, Tetsuya; Kawasaki, Masahiro

    2011-01-20

    Mixtures of water (H{sub 2}O) and carbon monoxide (CO) ices were irradiated at 10 K with energetic electrons to simulate the energy transfer processes that occur in the track of galactic cosmic-ray particles penetrating interstellar ices. We identified formic acid (HCOOH) through new absorption bands in the infrared spectra at 1690 and 1224 cm{sup -1} (5.92 and 8.17 {mu}m, respectively). During the subsequent warm-up of the irradiated samples, formic acid is evident from the mass spectrometer signal at the mass-to-charge ratio, m/z = 46 (HCOOH{sup +}) as the ice sublimates. The detection of formic acid was confirmed using isotopically labeled water-d2 with carbon monoxide, leading to formic acid-d2 (DCOOD). The temporal fits of the reactants, reaction intermediates, and products elucidate two reaction pathways to formic acid in carbon monoxide-water ices. The reaction is induced by unimolecular decomposition of water forming atomic hydrogen (H) and the hydroxyl radical (OH). The dominating pathway to formic acid (HCOOH) was found to involve addition of suprathermal hydrogen atoms to carbon monoxide forming the formyl radical (HCO); the latter recombined with neighboring hydroxyl radicals to yield formic acid (HCOOH). To a lesser extent, hydroxyl radicals react with carbon monoxide to yield the hydroxyformyl radical (HOCO), which recombined with atomic hydrogen to produce formic acid. Similar processes are expected to produce formic acid within interstellar ices, cometary ices, and icy satellites, thus providing alternative processes for the generation of formic acid whose abundance in hot cores such as Sgr-B2 cannot be accounted for solely by gas-phase chemistry.

  3. The facile synthesis of single crystalline palladium arrow-headed tripods and their application in formic acid electro-oxidation.

    PubMed

    Su, Na; Chen, Xueying; Ren, Yuanhang; Yue, Bin; Wang, Han; Cai, Wenbin; He, Heyong

    2015-04-28

    Single crystalline palladium arrow-headed tripods prepared via a simple one-pot strategy exhibit high electro-activity in formic acid oxidation, which could be a promising anodic catalyst for direct formic acid fuel cells.

  4. Formic Acid Triggers the “Acid Crash” of Acetone-Butanol-Ethanol Fermentation by Clostridium acetobutylicum▿

    PubMed Central

    Wang, Shaohua; Zhang, Yanping; Dong, Hongjun; Mao, Shaoming; Zhu, Yan; Wang, Runjiang; Luan, Guodong; Li, Yin

    2011-01-01

    Solvent production by Clostridium acetobutylicum collapses when cells are grown in pH-uncontrolled glucose medium, the so-called “acid crash” phenomenon. It is generally accepted that the fast accumulation of acetic acid and butyric acid triggers the acid crash. We found that addition of 1 mM formic acid into corn mash medium could trigger acid crash, suggesting that formic acid might be related to acid crash. When it was grown in pH-uncontrolled glucose medium or glucose-rich medium, C. acetobutylicum DSM 1731 containing the empty plasmid pIMP1 failed to produce solvents and was found to accumulate 0.5 to 1.24 mM formic acid intracellularly. In contrast, recombinant strain DSM 1731 with formate dehydrogenase activity did not accumulate formic acid intracellularly and could produce solvent as usual. We therefore conclude that the accumulation of formic acid, rather than acetic acid and butyric acid, is responsible for the acid crash of acetone-butanol-ethanol fermentation. PMID:21216898

  5. Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation.

    PubMed

    Oshoma, Cyprian E; Greetham, Darren; Louis, Edward J; Smart, Katherine A; Phister, Trevor G; Powell, Chris; Du, Chenyu

    2015-01-01

    Formic acid is one of the major inhibitory compounds present in hydrolysates derived from lignocellulosic materials, the presence of which can significantly hamper the efficiency of converting available sugars into bioethanol. This study investigated the potential for screening formic acid tolerance in non-Saccharomyces cerevisiae yeast strains, which could be used for the development of advanced generation bioethanol processes. Spot plate and phenotypic microarray methods were used to screen the formic acid tolerance of 7 non-Saccharomyces cerevisiae yeasts. S. kudriavzeii IFO1802 and S. arboricolus 2.3319 displayed a higher formic acid tolerance when compared to other strains in the study. Strain S. arboricolus 2.3319 was selected for further investigation due to its genetic variability among the Saccharomyces species as related to Saccharomyces cerevisiae and availability of two sibling strains: S. arboricolus 2.3317 and 2.3318 in the lab. The tolerance of S. arboricolus strains (2.3317, 2.3318 and 2.3319) to formic acid was further investigated by lab-scale fermentation analysis, and compared with S. cerevisiae NCYC2592. S. arboricolus 2.3319 demonstrated improved formic acid tolerance and a similar bioethanol synthesis capacity to S. cerevisiae NCYC2592, while S. arboricolus 2.3317 and 2.3318 exhibited an overall inferior performance. Metabolite analysis indicated that S. arboricolus strain 2.3319 accumulated comparatively high concentrations of glycerol and glycogen, which may have contributed to its ability to tolerate high levels of formic acid.

  6. Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation

    PubMed Central

    Oshoma, Cyprian E.; Greetham, Darren; Louis, Edward J.; Smart, Katherine A.; Phister, Trevor G.; Powell, Chris; Du, Chenyu

    2015-01-01

    Formic acid is one of the major inhibitory compounds present in hydrolysates derived from lignocellulosic materials, the presence of which can significantly hamper the efficiency of converting available sugars into bioethanol. This study investigated the potential for screening formic acid tolerance in non-Saccharomyces cerevisiae yeast strains, which could be used for the development of advanced generation bioethanol processes. Spot plate and phenotypic microarray methods were used to screen the formic acid tolerance of 7 non-Saccharomyces cerevisiae yeasts. S. kudriavzeii IFO1802 and S. arboricolus 2.3319 displayed a higher formic acid tolerance when compared to other strains in the study. Strain S. arboricolus 2.3319 was selected for further investigation due to its genetic variability among the Saccharomyces species as related to Saccharomyces cerevisiae and availability of two sibling strains: S. arboricolus 2.3317 and 2.3318 in the lab. The tolerance of S. arboricolus strains (2.3317, 2.3318 and 2.3319) to formic acid was further investigated by lab-scale fermentation analysis, and compared with S. cerevisiae NCYC2592. S. arboricolus 2.3319 demonstrated improved formic acid tolerance and a similar bioethanol synthesis capacity to S. cerevisiae NCYC2592, while S. arboricolus 2.3317 and 2.3318 exhibited an overall inferior performance. Metabolite analysis indicated that S. arboricolus strain 2.3319 accumulated comparatively high concentrations of glycerol and glycogen, which may have contributed to its ability to tolerate high levels of formic acid. PMID:26284784

  7. Lewis acid-assisted formic acid dehydrogenation using a pincer-supported iron catalyst.

    PubMed

    Bielinski, Elizabeth A; Lagaditis, Paraskevi O; Zhang, Yuanyuan; Mercado, Brandon Q; Würtele, Christian; Bernskoetter, Wesley H; Hazari, Nilay; Schneider, Sven

    2014-07-23

    Formic acid (FA) is an attractive compound for H2 storage. Currently, the most active catalysts for FA dehydrogenation use precious metals. Here, we report a homogeneous iron catalyst that, when used with a Lewis acid (LA) co-catalyst, gives approximately 1,000,000 turnovers for FA dehydrogenation. To date, this is the highest turnover number reported for a first-row transition metal catalyst. Preliminary studies suggest that the LA assists in the decarboxylation of a key iron formate intermediate and can also be used to enhance the reverse process of CO2 hydrogenation.

  8. Suicidal carbon monoxide poisoning by combining formic acid and sulfuric acid within a confined space.

    PubMed

    Lin, Peter T; Dunn, William A

    2014-01-01

    Suicide by inhalation of carbon monoxide produced by mixing formic acid and sulfuric acid within a confined space is a rare method of suicide. This method is similar to the so-called "detergent suicide" method where an acid-based detergent is mixed with a sulfur source to produce hydrogen sulfide. Both methods produce a toxic gas that poses significant hazards for death investigators, first responders and bystanders. Carbon monoxide is an odorless gas, while hydrogen sulfide has a characteristic rotten eggs odor, so the risks associated with carbon monoxide are potentially greater due to lack of an important warning signal. While detergent suicides have become increasingly common in the USA, suicide with formic acid and sulfuric acid is rare with only three prior cases being reported. Greater awareness of this method among death investigators is warranted because of the special risks of accidental intoxication by toxic gas and the possibility that this method of suicide will become more common in the future. © 2013 American Academy of Forensic Sciences.

  9. A large and ubiquitous source of atmospheric formic acid

    NASA Astrophysics Data System (ADS)

    Millet, D. B.; Baasandorj, M.; Farmer, D. K.; Thornton, J. A.; Baumann, K.; Brophy, P.; Chaliyakunnel, S.; de Gouw, J. A.; Graus, M.; Hu, L.; Koss, A.; Lee, B. H.; Lopez-Hilfiker, F. D.; Neuman, J. A.; Paulot, F.; Peischl, J.; Pollack, I. B.; Ryerson, T. B.; Warneke, C.; Williams, B. J.; Xu, J.

    2015-02-01

    Formic acid (HCOOH) is one of the most abundant acids in the atmosphere, with an important influence on precipitation chemistry and acidity. Here we employ a chemical transport model (GEOS-Chem) to interpret recent airborne and ground-based measurements over the US Southeast in terms of the constraints they provide on HCOOH sources and sinks. Summertime boundary layer concentrations average several parts-per-billion, 2-3× larger than can be explained based on known production and loss pathways. This indicates one or more large missing HCOOH sources, and suggests either a key gap in current understanding of hydrocarbon oxidation or a large, unidentified, direct flux of HCOOH. Model-measurement comparisons implicate biogenic sources (e.g., isoprene oxidation) as the predominant HCOOH source. Resolving the unexplained boundary layer concentrations based: (i) solely on isoprene oxidation would require a 3× increase in the model HCOOH yield, or (ii) solely on direct HCOOH emissions would require approximately a 25× increase in its biogenic flux. However, neither of these can explain the high HCOOH amounts seen in anthropogenic air masses and in the free troposphere. The overall indication is of a large biogenic source combined with ubiquitous chemical production of HCOOH across a range of precursors. Laboratory work is needed to better quantify the rates and mechanisms of carboxylic acid production from isoprene and other prevalent organics. Stabilized Criegee intermediates (SCIs) provide a large model source of HCOOH, while acetaldehyde tautomerization accounts for ~ 15% of the simulated global burden. Because carboxylic acids also react with SCIs and catalyze the reverse tautomerization reaction, HCOOH buffers against its own production by both of these pathways. Based on recent laboratory results, reaction between CH3O2 and OH could provide a major source of atmospheric HCOOH; however, including this chemistry degrades the model simulation of CH3OOH and NOx:CH3OOH

  10. A large and ubiquitous source of atmospheric formic acid

    NASA Astrophysics Data System (ADS)

    Millet, D. B.; Baasandorj, M.; Farmer, D. K.; Thornton, J. A.; Baumann, K.; Brophy, P.; Chaliyakunnel, S.; de Gouw, J. A.; Graus, M.; Hu, L.; Koss, A.; Lee, B. H.; Lopez-Hilfiker, F. D.; Neuman, J. A.; Paulot, F.; Peischl, J.; Pollack, I. B.; Ryerson, T. B.; Warneke, C.; Williams, B. J.; Xu, J.

    2015-06-01

    Formic acid (HCOOH) is one of the most abundant acids in the atmosphere, with an important influence on precipitation chemistry and acidity. Here we employ a chemical transport model (GEOS-Chem CTM) to interpret recent airborne and ground-based measurements over the US Southeast in terms of the constraints they provide on HCOOH sources and sinks. Summertime boundary layer concentrations average several parts-per-billion, 2-3× larger than can be explained based on known production and loss pathways. This indicates one or more large missing HCOOH sources, and suggests either a key gap in current understanding of hydrocarbon oxidation or a large, unidentified, direct flux of HCOOH. Model-measurement comparisons implicate biogenic sources (e.g., isoprene oxidation) as the predominant HCOOH source. Resolving the unexplained boundary layer concentrations based (i) solely on isoprene oxidation would require a 3× increase in the model HCOOH yield, or (ii) solely on direct HCOOH emissions would require approximately a 25× increase in its biogenic flux. However, neither of these can explain the high HCOOH amounts seen in anthropogenic air masses and in the free troposphere. The overall indication is of a large biogenic source combined with ubiquitous chemical production of HCOOH across a range of precursors. Laboratory work is needed to better quantify the rates and mechanisms of carboxylic acid production from isoprene and other prevalent organics. Stabilized Criegee intermediates (SCIs) provide a large model source of HCOOH, while acetaldehyde tautomerization accounts for ~ 15% of the simulated global burden. Because carboxylic acids also react with SCIs and catalyze the reverse tautomerization reaction, HCOOH buffers against its own production by both of these pathways. Based on recent laboratory results, reaction between CH3O2 and OH could provide a major source of atmospheric HCOOH; however, including this chemistry degrades the model simulation of CH3OOH and NOx

  11. Deprotonation of solvated formic acid: Car-Parrinello and metadynamics simulations.

    PubMed

    Lee, Jung-Goo; Asciutto, Eliana; Babin, Volodymyr; Sagui, Celeste; Darden, Thomas; Roland, Christopher

    2006-02-09

    The deprotonation of solvated formic acid was investigated theoretically with ab initio simulations. With the Car-Parrinello method, deprotonation and reprotonation by means of a proton wire were observed. The microscopics of these reactions were analyzed, and reveal the key role played by nearby water molecules in catalyzing the reactions. A constrained molecular dynamics calculation was carried out to estimate the dissociation free energy. Deprotonation of formic acid was further investigated with the recently developed metadynamics method using the formic acid oxygen coordination numbers as the collective variables. The determined free-energy landscape gives barriers similar to that obtained with the constrained free-energy calculation.

  12. Catalytic air oxidation of biomass-derived carbohydrates to formic acid.

    PubMed

    Li, Jiang; Ding, Dao-Jun; Deng, Li; Guo, Qing-Xiang; Fu, Yao

    2012-07-01

    An efficient catalytic system for biomass oxidation to form formic acid was developed. The conversion of glucose to formic acid can reach up to 52% yield within 3 h when catalyzed by 5 mol% of H(5)PV(2)Mo(10)O(40) at only 373 K using air as the oxidant. Furthermore, the heteropolyacid can be used as a bifunctional catalyst in the conversion of cellulose to formic acid (yield=35%) with air as the oxidant. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Polymerization of formic acid under high static pressure

    NASA Astrophysics Data System (ADS)

    Goncharov, A. F.; Manaa, M. R.; Zaug, J. M.; Fried, L. E.; Montgomery, W.

    2004-03-01

    We report the results of Raman and x-ray diffraction measurements in diamond anvil cell to 45 GPa and quantum molecular dynamic simulations to 70 GPa. Raman spectra and x-ray diffraction patterns indicate major changes at about 40 GPa with a large hysteresis at decompression. In contrast to the low-P solid, no lattice modes are observed in the Raman spectrum of a high-pressure phase; a few broad bands that are recorded correspond to C-H and C-O bonds. Below the transition, X-ray diffraction patterns are consistent with Pna21 space group; the pressure dependence of the lattice constants and the unit cell volume are determined. Theoretical calculations are in agreement and indicate the proximity of the intra- and intermolecular O-H distances above 30 GPa, which suggest the symmetrization of hydrogen bond under compression. We conjecture that the structure of the high-pressure formic acid consists of infinite polymeric chains; the significant decrease in intensity of x-ray diffraction pattern may indicate a partial loss of the long-range order.

  14. Organic acids as indicators of VOC oxidation: Measurements of formic acid and other gas-phase acids during SOAS

    NASA Astrophysics Data System (ADS)

    Farmer, D.; Brophy, P.; Murschell, T.

    2013-12-01

    Oxidation of volatile organic compounds (VOCs) in the atmosphere affects not only the oxidative capacity of the atmosphere, but also the formation of secondary organic aerosol. Organic acids are produced during VOC oxidation, although additional sources include biomass burning and primary emissions. While some organic acids are semi-volatile and dominantly present in the aerosol phase, formic acid and other small organic acids are dominantly present in the gas phase. The concentrations of these gas-phase organic acids can provide insight into oxidation chemistry. Here, we present measurements made during the Southern Oxidant and Aerosol Study (SOAS) in Centerville, Alabama during the summer of 2013 by a high resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) operated in a novel switching reagent ion mode to measure gas phase organic acids with both acetate (CH3COO-) and iodide (I-) reagent ions. Formic acid was quantified using for both ionization schemes using multiple calibration techniques. In this study, we will focus on the impact of anthropogenic pollutants, including nitrogen and sulfur oxides, on oxidation chemistry, and discuss the potential use of organic acids as tracers for atmospheric oxidation chemistry.

  15. Laboratory and field measurements to constrain atmospheric sources of acetic and formic acids

    NASA Astrophysics Data System (ADS)

    Baasandorj, M.; Hu, L.; Mitroo, D.; Martinez, R.; Walker, M.; Williams, B. J.; Millet, D. B.

    2013-12-01

    Acetic and formic acids are the most abundant organic acids in the atmosphere. They play an important role in atmospheric aqueous chemistry as they can influence the acidity of precipitation, cloud droplets, and atmospheric aerosols. Sources of these acids are highly uncertain, but include secondary production from VOC oxidation, direct emissions, and possibly organic aerosol aging. Here we present measurements of formic and acetic acid, along with a suite of other gas and particle phase species, from a field study in St. Louis during summer 2013. Calibration procedures and results are discussed, and we interpret the ambient formic and acetic acid measurements in terms of patterns of variability and implied constraints on sources. Finally, we present results from oxidative aging experiments on both ambient and test organic aerosol designed to assess the importance of this mechanism as a source of gas-phase carboxylic acids.

  16. Kinetics of gas phase formic acid decomposition on platinum single crystal and polycrystalline surfaces

    NASA Astrophysics Data System (ADS)

    Detwiler, Michael D.; Milligan, Cory A.; Zemlyanov, Dmitry Y.; Delgass, W. Nicholas; Ribeiro, Fabio H.

    2016-06-01

    Formic acid dehydrogenation turnover rates (TORs) were measured on Pt(111), Pt(100), and polycrystalline Pt foil surfaces at a total pressure of 800 Torr between 413 and 513 K in a batch reactor connected to an ultra-high vacuum (UHV) system. The TORs, apparent activation energies, and reaction orders are not sensitive to the structure of the Pt surface, within the precision of the measurements. CO introduced into the batch reactor depressed the formic acid dehydrogenation TOR and increased the reaction's apparent activation energies on Pt(111) and Pt(100), consistent with behavior predicted by the Temkin equation. Two reaction mechanisms were explored which explain the formic acid decomposition mechanism on Pt, both of which include dissociative adsorption of formic acid, rate limiting formate decomposition, and quasi-equilibrated hydrogen recombination and CO adsorption. No evidence was found that catalytic supports used in previous studies altered the reaction kinetics or mechanism.

  17. 40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance...

  18. 40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance...

  19. 40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance...

  20. 40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance...

  1. Photoelectrocatalytic Oxidation of Formic Acid at Titania@Polyoxometalate/Gold Nanocomposite Material Modified Electrode.

    PubMed

    Pandiyarajan, Chinnappan; Pandikumar, Alagarsamy; Ramaraj, Ramasamy

    2015-09-01

    Amine functionalized silicate sol-gel stabilized titania (P25)-polyoxometalate (PTA)-gold (Au) nanocomposite materials (APS/(P25-PTA-Au)(NCM)) were prepared by a simple chemical reduction method and were used to fabricate modified photoelectrode for the photoelectrocatalytic oxidation of formic acid. The APS/(P25-PTA-Au)(NCM) photoelectrode showed synergistic photoelectrocatalytic behavior towards the oxidation of formic acid. The photoresponse of the APS/(P25-PTA-Au)(NCM) modified photoelectrode was found to be higher when compared to the controlled photoelectrodes. The present study shows that the loading of Au(nps) on APS/P25-PTA is more beneficial to enhance the photoinduced interfacial charge transfer process, which leads to increased photocurrent generation. The present study concludes that the photoelectrocatalytic oxidation of formic acid at the APS/(P25-PTA-Au)(NCM) photoelectrode will boost the formic acid fuel cell performance.

  2. Flavin-catalyzed aerobic oxidation of sulfides and thiols with formic acid/triethylamine.

    PubMed

    Murahashi, Shun-Ichi; Zhang, Dazhi; Iida, Hiroki; Miyawaki, Toshio; Uenaka, Masaaki; Murano, Kenji; Meguro, Kanji

    2014-09-14

    An efficient and practical catalytic method for the aerobic oxidative transformation of sulfides into sulfoxides, and thiols into disulfides with formic acid/TEA in the presence of a new, readily available, and stable flavin catalyst 5d is described.

  3. Novel palladium flower-like nanostructured networks for electrocatalytic oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Ren, Mingjun; Zou, Liangliang; Yuan, Ting; Huang, Qinghong; Zou, Zhiqing; Li, Xuemei; Yang, Hui

    2014-12-01

    Novel Pd flower-like nanostructured networks are synthesized via a simple CO-assisted reduction. The morphology and size of the Pd nanostructures are found to strongly depend on the temperature and solvent during the synthesis process. Such Pd flower-like nanostructured networks exhibit a much enhanced activity of about 3 times of that on conventional Pd nanoparticles towards the electrocatalytic oxidation of formic acid. The specific activity of formic acid oxidation on Pd nanostructures is also greatly improved, indicating that the formation of flower-like nanostructured networks is beneficial for the electrooxidation of formic acid. Thus, it could be served as highly active catalyst for formic acid electrooxidation although the stability needs to be greatly improved.

  4. High-efficiency palladium catalysts supported on ppy-modified C60 for formic acid oxidation.

    PubMed

    Bai, Zhengyu; Yang, Lin; Guo, Yuming; Zheng, Zhi; Hu, Chuangang; Xu, Pengle

    2011-02-14

    A facile preparation of polypyrrole-modified fullerene supported Pd nanoparticles catalyst is introduced; electrochemical measurements demonstrate that the obtained Pd/ppy-C(60) catalyst shows a good electrocatalytic activity and stability for the oxidation of formic acid.

  5. Properties of nanocellulose isolated from corncob residue using sulfuric acid, formic acid, oxidative and mechanical methods.

    PubMed

    Liu, Chao; Li, Bin; Du, Haishun; Lv, Dong; Zhang, Yuedong; Yu, Guang; Mu, Xindong; Peng, Hui

    2016-10-20

    In this work, nanocellulose was extracted from bleached corncob residue (CCR), an underutilized lignocellulose waste from furfural industry, using four different methods (i.e. sulfuric acid hydrolysis, formic acid (FA) hydrolysis, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and pulp refining, respectively). The self-assembled structure, morphology, dimension, crystallinity, chemical structure and thermal stability of prepared nanocellulose were investigated. FA hydrolysis produced longer cellulose nanocrystals (CNCs) than the one obtained by sulfuric acid hydrolysis, and resulted in high crystallinity and thermal stability due to its preferential degradation of amorphous cellulose and lignin. The cellulose nanofibrils (CNFs) with fine and individualized structure could be isolated by TEMPO-mediated oxidation. In comparison with other nanocellulose products, the intensive pulp refining led to the CNFs with the longest length and the thickest diameter. This comparative study can help to provide an insight into the utilization of CCR as a potential source for nanocellulose production.

  6. Proteomic Evaluation of Cellular Responses of Saccharomyces cerevisiae to Formic Acid Stress

    PubMed Central

    Lee, Sung-Eun; Park, Byeoung-Soo

    2010-01-01

    Formic acid is a representative carboxylic acid that inhibits bacterial cell growth, and thus it is generally considered to constitute an obstacle to the reuse of renewable biomass. In this study, Saccharomyces cerevisiae was used to elucidate changes in protein levels in response to formic acid. Fifty-seven differentially expressed proteins in response to formic acid toxicity in S. cerevisiae were identified by 1D-PAGE and nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) analyses. Among the 28 proteins increased in expression, four were involved in the MAP kinase signal transduction pathway and one in the oxidative stress-induced pathway. A dramatic increase was observed in the number of ion transporters related to maintenance of acid-base balance. Regarding the 29 proteins decreased in expression, they were found to participate in transcription during cell division. Heat shock protein 70, glutathione reductase, and cytochrome c oxidase were measured by LC-MS/MS analysis. Taken together, the inhibitory action of formic acid on S. cerevisiae cells might disrupt the acid-base balance across the cell membrane and generate oxidative stress, leading to repressed cell division and death. S. cerevisiae also induced expression of ion transporters, which may be required to maintain the acid-base balance when yeast cells are exposed to high concentrations of formic acid in growth medium. PMID:23956670

  7. Efficient electrocatalytic oxidation of formic acid using Au@Pt dendrimer-encapsulated nanoparticles.

    PubMed

    Iyyamperumal, Ravikumar; Zhang, Liang; Henkelman, Graeme; Crooks, Richard M

    2013-04-17

    We report electrocatalytic oxidation of formic acid using monometallic and bimetallic dendrimer-encapsulated nanoparticles (DENs). The results indicate that the Au147@Pt DENs exhibit better electrocatalytic activity and low CO formation. Theoretical calculations attribute the observed activity to the deformation of nanoparticle structure, slow dehydration of formic acid, and weak binding of CO on Au147@Pt surface. Subsequent experiments confirmed the theoretical predictions.

  8. Tungsten carbide promoted Pd and Pd-Co electrocatalysts for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Yin, Min; Li, Qingfeng; Jensen, Jens Oluf; Huang, Yunjie; Cleemann, Lars N.; Bjerrum, Niels J.; Xing, Wei

    2012-12-01

    Tungsten carbide (WC) promoted palladium (Pd) and palladium-cobalt (Pd-Co) nanocatalysts are prepared and characterized for formic acid electrooxidation. The WC as the dopant to carbon supports is found to enhance the CO tolerance and promote the activity of the Pd-based catalysts for formic acid oxidation. Alloying of Pd with Co further improves the electrocatalytic activity and stability of the WC supported catalysts, attributable to a synergistic effect of the carbide support and PdCo alloy nanoparticles.

  9. Copper-catalyzed formic acid synthesis from CO2 with hydrosilanes and H2O.

    PubMed

    Motokura, Ken; Kashiwame, Daiki; Miyaji, Akimitsu; Baba, Toshihide

    2012-05-18

    A copper-catalyzed formic acid synthesis from CO2 with hydrosilanes has been accomplished. The Cu(OAc)2·H2O-1,2-bis(diphenylphosphino)benzene system is highly effective for the formic acid synthesis under 1 atm of CO2. The TON value approached 8100 in 6 h. The reaction pathway was revealed by in situ NMR analysis and isotopic experiments.

  10. Formic acid as an alternative reducing agent for the catalytic nitrate reduction in aqueous media.

    PubMed

    Choi, Eun-Kyoung; Park, Kuy-Hyun; Lee, Ho-Bin; Cho, Misun; Ahn, Samyoung

    2013-08-01

    Formic acid was used for the nitrate reduction as a reductant in the presence of Pd:Cu/gamma-alumina catalysts. The surface characteristics of the bimetallic catalyst synthesized by wet impregnation were investigated by SEM, TEM-EDS. The metals were not distributed homogeneously on the surface of catalyst, although the total contents of both metals in particles agreed well with the theoretical values. Formic acid decomposition on the catalyst surface, its influence on solution pH and nitrate removal efficacy was investigated. The best removal of nitrate (50 ppm) was obtained under the condition of 0.75 g/L catalyst with Pd:Cu ratio (4:1) and two fold excess of formic acid. Formic acid decay patterns resembled those of nitrate removal, showing a linear relationship between k(f) (formic acid decay) and k (nitrate removal). Negligible amount of ammonia was detected, and no nitrite was detected, possibly due to buffering effect of bicarbonate that is in situ produced by the decomposition of formic acid, and due to the sustained release of H2 gas.

  11. The Mechanism of Direct Formic Acid Fuel Cell Using Pd, Pt and Pt-Ru

    NASA Astrophysics Data System (ADS)

    Kamiya, Nobuyuki; Liu, Yan; Mitsushima, Shigenori; Ota, Ken-Ichiro; Tsutsumi, Yasuyuki; Ogawa, Naoya; Kon, Norihiro; Eguchi, Mika

    The electro-oxidation of formic acid, 2-propanol and methanol on Pd black, Pd/C, Pt-Ru/C and Pt/C has been investigated to clear the reaction mechanism. It was suggested that the formic acid is dehydrogenated on Pd surface and the hydrogen is occluded in the Pd lattice. Thus obtained hydrogen acts like pure hydrogen supplied from the outside and the cell performance of the direct formic acid fuel cell showed as high as that of a hydrogen-oxygen fuel cell. 2-propanol did not show such dehydrogenation reaction on Pd catalyst. Platinum and Pt-Ru accelerated the oxidation of C-OH of 2-propanol and methanol. Slow scan voltammogram (SSV) and chronoamperometry measurements showed that the activity of formic acid oxidation increased in the following order: Pd black > Pd 30wt.%/C > Pt50wt.%/C > 27wt.%Pt-13wt.%Ru/C. A large oxidation current for formic acid was found at a low overpotential on the palladium electrocatalysts. These results indicate that formic acid is mainly oxidized through a dehydrogenation reaction. For the oxidation of 2-propanol and methanol, palladium was not effective, and 27wt.%Pt-13wt.%Ru/C showed the best oxidation activity.

  12. Deactivation of carbon supported palladium catalyst in direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Mikołajczuk, A.; Borodzinski, A.; Kedzierzawski, P.; Stobinski, L.; Mierzwa, B.; Dziura, R.

    2011-07-01

    A new carbon black supported palladium catalyst for direct formic acid fuel cell applications has been prepared and characterized by X-ray diffraction. Bi-modal distribution of Pd crystallite sizes was observed. The average Pd size for crystallites in small size and large size ranges were about 2.7 nm and 11.2 nm, respectively. The initial activity of the catalyst in the oxidation of formic acid tested in a fuel cell was similar to a commercial well dispersed 20 wt.% Pd/Vulcan. The rates of the fuel cell power decay were measured for formic acid of two purities for various current loadings. The results showed that various mechanisms contribute to the decrease of cell power with time. In direct formic acid fuel cell (DFAFC) fed with a very pure HCOOH accumulation of CO 2 gas bubbles in anode catalyst layer is responsible for observed power decay. In DFAFC fed with a pure for analysis (p.a.) grade formic acid the formation of CO ads poison from the formic acid impurities is the main deactivation reason.

  13. Carbon-supported Pd-Ir catalyst as anodic catalyst in direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Tang, Yawen; Gao, Ying; Lu, Tianhong

    It was reported for the first time that the electrocatalytic activity of the Carbon-supported Pd-Ir (Pd-Ir/C) catalyst with the suitable atomic ratio of Pd and Ir for the oxidation of formic acid in the direct formic acid fuel cell (DFAFC) is better than that of the Carbon-supported Pd (Pd/C) catalyst, although Ir has no electrocatalytic activity for the oxidation of formic acid. The potential of the anodic peak of formic acid at the Pd-Ir/C catalyst electrode with the atomic ratio of Pd and Ir = 5:1 is 50 mV more negative than that and the peak current density is 13% higher than that at the Pd/C catalyst electrode. This is attributed to that Ir can promote the oxidation of formic acid at Pd through the direct pathway because Ir can decrease the adsorption strength of CO on Pd. However, when the content of Ir in the Pd-Ir/C catalyst is too high the electrocatalytic activity of the Pd-Ir/C catalyst would be decreased because Ir has no electrocatalytic activity for the oxidation of formic acid.

  14. Structure and NLO properties of halogen (F, Cl) substituted formic acid dimers.

    PubMed

    Umadevi, P; Senthilkumar, L; Gayathri, M; Kolandaivel, P

    2014-11-11

    In this work, using ab initio and density functional theory (DFT) methods halogen substituted formic acid (FA) dimer is studied. The dimer stability is due to the hydrogen bonds, either conventional (OH⋯O, OH⋯F, OH⋯Cl) or non-conventional (CH⋯O, CH⋯F, CH⋯Cl). Among all the dimers, trans-trans form is more stable than the trans-cis, and cis-cis form. Basis set extrapolated counterpoise corrected interaction energy results for the FA dimer are in excellent agreement with BSSE corrected MP2 interaction energy. Symmetry Adopted Perturbation Theory (SAPT) analysis reveals that the electrostatic effect plays a dominant role in stabilization among the dimers with maximum interaction energy. Chlorine substituted FA dimer has high hyperpolarizability, which makes them excellent candidate for nonlinear optical materials (NLO). The halogen substituted formic acid dimers have higher stability and polarizability value than the unsubstituted formic acid dimer. The hyperpolarizability values depend on the geometrical structures of halogenated formic acid dimers than the type of hydrogen bonds. The small excitation energy and HOMO-LUMO gap in the halogenated formic acid dimer has led to the strong nonlinear optical response. The depolarization ratio and Rayleigh scattering increases in formic acid dimer after the halogen atom substitution. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Kinetics and toxic effects of repeated intravenous dosage of formic acid in rabbits.

    PubMed Central

    Liesivuori, J.; Kosma, V. M.; Naukkarinen, A.; Savolainen, H.

    1987-01-01

    Adult male rabbits were injected i.v. with 100 mg buffered formic acid per kg body weight daily for 5 days with 24 h between the doses. The fifth dose was labelled with 14C-formic acid. Rabbits were killed 1, 2 and 20 h after the last injection. The highest formic acid concentrations were found one hour after the fifth dose. Total formic acid concentrations were always higher than radiometrically measured. The maximum concentrations of formic acid in brain, heart, kidney and liver were roughly similar to the concentration which inhibits half of the cytochrome oxidase activity in vitro. Histological studies clearly demonstrated the histotoxic changes at cellular level. Calcium deposits were detected in all organs of the injected rabbits. They were absent in control animals. It seems that the formic acid metabolism is slow and that it may cause sufficient hypoxic acidosis to allow the calcium influx and cellular damage. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:3426949

  16. Atmospheric geochemistry of formic and acetic acids at a mid-latitude temperate site

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Beecher, K. M.; Harriss, R. C.; Cofer, R. W., III

    1988-01-01

    Tropospheric concentrations of formic and acetic acids in the gas, the aerosol, and the rainwater phases were determined in samples collected 1-2 m above ground level at an open field site in eastern Virginia. These acids were found to occur principally (98 percent or above) in the gas phase, with a marked annual seasonality, averaging 1890 ppt for formate and 1310 ppt for acetate during the growing season, as compared to 695 ppt and 700 ppt, respectively, over the nongrowing season. The data support the hypothesis that biogenic emissions from vegatation are important sources of atmospheric formic and acetic acid during the local growing season. The same time trends were observed for precipitation, although with less defined seasonality. The relative increase of the acetic acid/formic acid ratio during the nongrowing season points to the dominance of anthropogenic inputs of acetic acid from motor vehicles and biomass combustion in the wintertime.

  17. Atmospheric geochemistry of formic and acetic acids at a mid-latitude temperate site

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Beecher, K. M.; Harriss, R. C.; Cofer, R. W., III

    1988-01-01

    Tropospheric concentrations of formic and acetic acids in the gas, the aerosol, and the rainwater phases were determined in samples collected 1-2 m above ground level at an open field site in eastern Virginia. These acids were found to occur principally (98 percent or above) in the gas phase, with a marked annual seasonality, averaging 1890 ppt for formate and 1310 ppt for acetate during the growing season, as compared to 695 ppt and 700 ppt, respectively, over the nongrowing season. The data support the hypothesis that biogenic emissions from vegatation are important sources of atmospheric formic and acetic acid during the local growing season. The same time trends were observed for precipitation, although with less defined seasonality. The relative increase of the acetic acid/formic acid ratio during the nongrowing season points to the dominance of anthropogenic inputs of acetic acid from motor vehicles and biomass combustion in the wintertime.

  18. Formic-acid-induced depolymerization of oxidized lignin to aromatics

    NASA Astrophysics Data System (ADS)

    Rahimi, Alireza; Ulbrich, Arne; Coon, Joshua J.; Stahl, Shannon S.

    2014-11-01

    Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.

  19. Formic-acid-induced depolymerization of oxidized lignin to aromatics.

    PubMed

    Rahimi, Alireza; Ulbrich, Arne; Coon, Joshua J; Stahl, Shannon S

    2014-11-13

    Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.

  20. Development of a gel formulation of formic acid for control of parasitic mites of honey bees.

    PubMed

    Kochansky, J; Shimanuki, H

    1999-09-01

    Formic acid has been used in various countries for the control of parasitic mites of honey bees (Apis mellifera), particularly the Varroa mite (Varroa jacobsoni) and the tracheal mite (Acarapis woodi). Its corrosivity and consequent fear of liability have precluded commercial interest in the United States, and its rapid vaporization requires frequent reapplication. We have developed a gel formulation of formic acid which provides controlled release over 2-3 weeks and improves the convenience and safety of handling of formic acid. The strong acidity of formic acid restricts the choice of gelling agents; vegetable gellants such as agar are destroyed, and bentonite clay derivatives do not gel, even with high-shear mixing. Polyacrylamides lead to viscous liquids lacking thixotropic properties. High-molecular-weight poly(acrylic acids) and fumed silicas provided gels with suitable physical characteristics. The poly(acrylic acid) gels were difficult to mix and gave slower and nonlinear release behavior, while the fumed silica gels were easy to prepare and linear in formic acid vaporization.

  1. Pd/C synthesized with citric acid: an efficient catalyst for hydrogen generation from formic acid/sodium formate.

    PubMed

    Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

    2012-01-01

    A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H(2) mol(-1) catalyst h(-1), respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells.

  2. Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

    PubMed Central

    Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

    2012-01-01

    A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H2 mol−1 catalyst h−1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells. PMID:22953041

  3. Microwave Spectroscopy and Proton Transfer Dynamics in the Formic Acid-Acetic Acid Dimer

    NASA Astrophysics Data System (ADS)

    Howard, B. J.; Steer, E.; Page, F.; Tayler, M.; Ouyang, B.; Leung, H. O.; Marshall, M. D.; Muenter, J. S.

    2012-06-01

    The rotational spectrum of the doubly hydrogen-bonded {hetero} dimer formed between formic acid and acetic acid has been recorded between 4 and 18 GHz using a pulsed-nozzle Fourier transform microwave spectrometer. Each rigid-molecule rotational transition is split into four as a result of two concurrent tunnelling motions, one being proton transfer between the two acid molecules, and the other the torsion/rotation of the methyl group within the acetic acid. We present a full assignment of the spectrum for {J} = 1 to {J} = 7 for these four torsion/tunnelling states. Spectra have been observed for the main isotopic species, with deuterium substitution at the C of the formic acid and all 13C species in natural abundance, The observed transitions are fitted to within a few kilohertz using a molecule-fixed effective rotational Hamiltonian for the separate {A} and {E} vibrational species of the G12 permutation-inversion group which is applicable to this complex. To reduce the effects of internal angular momentum, a non-principal axis system is used throughout. Interpretation of the internal motion uses an internal-vibration and overall rotation scheme, and full sets of rotational and centrifugal distortion constants are determined. The proton tunnelling rates and the internal angular momentum of the methyl group in the {E} states is interpreted in terms of a dynamical model which involves coupled proton transfer and internal rotation. The resulting potential energy surface not only describes these internal motions, but can also explain the observed shifts in rotational constants between {A} and {E} species, and the deviations of the tunnelling frequencies from the expected 2:1 ratio. It also permits the determination of spectral constants free from the contamination effects of the internal dynamics. M.C.D. Tayler, B. Ouyang and B.J. Howard, J. Chem. Phys., {134}, 054316 (2011).

  4. Solid Molecular Phosphine Catalysts for Formic Acid Decomposition in the Biorefinery.

    PubMed

    Hausoul, Peter J C; Broicher, Cornelia; Vegliante, Roberta; Göb, Christian; Palkovits, Regina

    2016-04-25

    The co-production of formic acid during the conversion of cellulose to levulinic acid offers the possibility for on-site hydrogen production and reductive transformations. Phosphorus-based porous polymers loaded with Ru complexes exhibit high activity and selectivity in the base-free decomposition of formic acid to CO2 and H2 . A polymeric analogue of 1,2-bis(diphenylphosphino)ethane (DPPE) gave the best results in terms of performance and stability. Recycling tests revealed low levels of leaching and only a gradual decrease in the activity over seven runs. An applicability study revealed that these catalysts even facilitate selective removal of formic acid from crude product mixtures arising from the synthesis of levulinic acid.

  5. Formic Acid Free Flowsheet Development To Eliminate Catalytic Hydrogen Generation In The Defense Waste Processing

    SciTech Connect

    Lambert, Dan P.; Stone, Michael E.; Newell, J. David; Fellinger, Terri L.; Bricker, Jonathan M.

    2012-09-14

    The Defense Waste Processing Facility (DWPF) processes legacy nuclear waste generated at the Savannah River Site (SRS) during production of plutonium and tritium demanded by the Cold War. The nuclear waste is first treated via a complex sequence of controlled chemical reactions and then vitrified into a borosilicate glass form and poured into stainless steel canisters. Converting the nuclear waste into borosilicate glass canisters is a safe, effective way to reduce the volume of the waste and stabilize the radionuclides. Testing was initiated to determine whether the elimination of formic acid from the DWPF's chemical processing flowsheet would eliminate catalytic hydrogen generation. Historically, hydrogen is generated in chemical processing of alkaline High Level Waste sludge in DWPF. In current processing, sludge is combined with nitric and formic acid to neutralize the waste, reduce mercury and manganese, destroy nitrite, and modify (thin) the slurry rheology. The noble metal catalyzed formic acid decomposition produces hydrogen and carbon dioxide. Elimination of formic acid by replacement with glycolic acid has the potential to eliminate the production of catalytic hydrogen. Flowsheet testing was performed to develop the nitric-glycolic acid flowsheet as an alternative to the nitric-formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be reduced and removed by steam stripping in DWPF with no catalytic hydrogen generation. All processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Ten DWPF tests were performed with nonradioactive simulants designed to cover a broad compositional range. No hydrogen was generated in testing without formic acid.

  6. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

    PubMed Central

    Kawasaki, Shin-ichiro; Suzuki, Akira

    2013-01-01

    Summary The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid. PMID:23843908

  7. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors.

    PubMed

    Javaid, Rahat; Kawasaki, Shin-Ichiro; Suzuki, Akira; Suzuki, Toshishige M

    2013-01-01

    The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd-Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid.

  8. Evaluation of the effect of formic acid and sodium formate on hair reduction in rat.

    PubMed

    Banihashemi, Mahnaz; Rad, Abolfazl Khajavi; Yazdi, Seyed Abbas Tabatabaee; Rakhshande, Hasan; Ghoyonlo, Vahid Mashayekhi; Zabihi, Zahra; Yousefzadeh, Hadis

    2011-01-01

    Hirsutism is a common problem in dermatology that imposes high socioeconomical costs on medical care. Consequently, researchers are actively searching for cheaper and safer methods for therapeutic treatment. The objective of the present study is to evaluate formic oil, enriched from formic acid, for the removal of unwanted hair. In this study, 32 female rats (150-200 g) were randomly divided into four groups and maintained with normal water and food availability. A patch of skin was shaved on each rat for application of test solutions. The control group was treated with local once-daily applications of normal saline. The formic acid, acetic acid, and sodium formate groups were treated with once-daily applications of formic acid (pH 5.5), acetic acid (pH 5.5), or sodium formate, respectively. After 2 weeks, horizontally cut sample biopsies were removed, and the numbers of hair follicles were counted under high field microscopy by a specialist blinded to the treatments. Kolmogorov-Smirnov test results indicated a nonparametric distribution for the rat groups. ANOVA analysis indicated no statistically significant differences between groups (P < 0.05). There weren't any side effects or evidence for toxicity during the study period. However, hair follicle counts showed a descending order of control, acetic acid, formic acid, and sodium formate. Although the sodium formate group had the lowest hair follicle numbers, the difference was not statistically significant (P > 0.05). Formic acid was not effective in reducing hair follicle numbers in rats.

  9. Uptake of formic acid on thin ice films and on ice doped with nitric acid between 195 and 211 K.

    PubMed

    Romanias, Manolis N; Zogka, Antonia G; Stefanopoulos, Vassileios G; Papadimitriou, Vassileios C; Papagiannakopoulos, Panos

    2010-12-17

    The adsorption of formic acid on thin ice films and on ice doped with nitric acid (1.96, 7.69 and 53.8 wt%) is studied as a function of temperature T=195-211 K and gas concentration (0.33-10.6)×10(11) molecule cm(-3). Experiments are performed in a Knudsen flow reactor coupled with a quadrupole mass spectrometer. The initial uptake coefficients γ are strongly and inversely dependent on the ice temperature. Initial uptake is determined at low surface coverages and ranges from (0.65-3.78)×10(-3). The adsorption uptake of formic acid on pure ice films and on ice lightly doped with HNO(3) is a reversible process, and the adsorption isotherms exhibit Langmuir behaviour. N(max)(1) is (2.94±0.67)×10(14) molecule cm(-2), in good agreement with previous measurements. The temperature dependence of K(Lin) is very well represented by the expression: K(Lin)(1)=(1.43±0.32)×10(-8) exp[(4720±520)/T] cm(3) molecule(-1); the quoted uncertainty is at the 95% level of confidence and includes systematic uncertainties. Formic acid uptakes on ice films highly doped with HNO(3) (53.8 wt%) are two orders of magnitude higher than those measured on pure ice films and irreversible, thus indicating the formation of a supercooled liquid layer on the ice films upon which dissolution of formic acid occurs. Finally, the atmospheric lifetime of formic acid due to heterogeneous loss on cirrus cloud ice particles and the removal of formic acid by adsorption are estimated under conditions related to the upper troposphere.

  10. On the mechanism of the direct pathway for formic acid oxidation at a Pt(111) electrode.

    PubMed

    Xu, Jie; Yuan, Daofu; Yang, Fan; Mei, Dong; Zhang, Zunbiao; Chen, Yan-Xia

    2013-03-28

    In order determine whether formate is a reaction intermediate of the direct pathway for formic acid oxidation at a Pt electrode, formic acid (HCOOH) oxidation at a Pt(111) electrode has been studied by normal and fast scan voltammetry in 0.1 M HClO4 solutions with different HCOOH concentrations. The relationship between the HCOOH oxidation current density (j(ox)) and formate coverage (θ(formate)) is quantitatively analyzed. The kinetic simulation reveals that the previously proposed formate pathway, with decomposition of the bridge-bonded formate (HCOO(B)) as a rate determining step (rds), cannot be the main pathway responsible for the majority of the current for HCOOH oxidation. Instead, a kinetic model based on a mechanism with formic acid adsorption [structure: see text], along with simultaneous C-H bond activation as the rds for the direct pathway, explains the measured data well. It was found for the relatively slow rate of formic acid oxidation, that adsorption-desorption of the formate is faster, which competes for the surface sites for formic acid oxidation.

  11. Coke-free direct formic acid solid oxide fuel cells operating at intermediate temperatures

    NASA Astrophysics Data System (ADS)

    Chen, Yubo; Su, Chao; Zheng, Tao; Shao, Zongping

    2012-12-01

    Formic acid is investigated as a fuel for Solid Oxide Fuel Cells (SOFCs) for the first time. Thermodynamic calculations demonstrate that carbon deposition is avoidable above 600 °C. The carbon deposition properties are also investigated experimentally by first treating a nickel plus yttria-stabilized zirconia (Ni-YSZ) anode material in particle form under a formic acid-containing atmosphere for a limited time at 500-800 °C and then analyzing the particles by O2-TPO. This analysis confirms that carbon deposition on Ni-YSZ is weak above 600 °C. We further treat half-cells composed of YSZ electrolyte and Ni-YSZ anode under formic acid-containing atmosphere at 600, 700 and 800 °C; the anodes maintain their original geometric shape and microstructure and show no obvious weight gain. It suggests that formic acid can be directly fed into SOFCs constructed with conventional nickel-based cermet anodes. I-V tests show that the cell delivers a promising peak power density of 571 mW cm-2 at 800 °C. In addition, the cells also show good performance stability. The results indicate that formic acid is highly promising as a direct fuel for SOFCs without the need for cell material modifications.

  12. Hanford waste vitrification plant hydrogen generation study: Preliminary evaluation of alternatives to formic acid

    SciTech Connect

    King, R.B.; Bhattacharyya, N.K.; Kumar, V.

    1996-02-01

    Oxalic, glyoxylic, glycolic, malonic, pyruvic, lactic, levulinic, and citric acids as well as glycine have been evaluated as possible substitutes for formic acid in the preparation of feed for the Hanford waste vitrification plant using a non-radioactive feed stimulant UGA-12M1 containing substantial amounts of aluminum and iron oxides as well as nitrate and nitrite at 90C in the presence of hydrated rhodium trichloride. Unlike formic acid none of these carboxylic acids liberate hydrogen under these conditions and only malonic and citric acids form ammonia. Glyoxylic, glycolic, malonic, pyruvic, lactic, levulinic, and citric acids all appear to have significant reducing properties under the reaction conditions of interest as indicated by the observation of appreciable amounts of N{sub 2}O as a reduction product of,nitrite or, less likely, nitrate at 90C. Glyoxylic, pyruvic, and malonic acids all appear to be unstable towards decarboxylation at 90C in the presence of Al(OH){sub 3}. Among the carboxylic acids investigated in this study the {alpha}-hydroxycarboxylic acids glycolic and lactic acids appear to be the most interesting potential substitutes for formic acid in the feed preparation for the vitrification plant because of their failure to produce hydrogen or ammonia or to undergo decarboxylation under the reaction conditions although they exhibit some reducing properties in feed stimulant experiments.

  13. Microwave Measurements of the Tropolone-Formic Acid Doubly Hydrogen Bonded DIMER*

    NASA Astrophysics Data System (ADS)

    Pejlovas, Aaron M.; Serrato, Agapito, III; Lin, Wei; Kukolich, Stephen G.

    2016-06-01

    The microwave spectrum was measured for the tropolone-formic acid doubly hydrogen bonded dimer using a pulsed-beam Fourier transform microwave spectrometer in order to search for the concerted double proton tunneling motion. The tunneling motion was expected for the dimer, as the transition state of this motion exhibits C_2_V symmetry, which has been thought to be a requirement to observe the concerted double proton tunneling. The tunneling motion was not observed for this dimer, as the transitions measured did not show observable splittings into doublets. The barrier height calculated of the dimer using B3LYP/aug-cc-pVTZ was about 15000 cm^-^1, significantly larger than the value determined for the propiolic acid-formic acid dimer (3800 cm^-^1),^a which showed the tunneling motion. The estimated separation of the minima in the potential energy surface is estimated to be very similar to that of propiolic acid-formic acid (about 0.8 Å),^a so the large barrier height may be why the tunneling process was not observed. ^aDaly, A. M.; Bunker, P. R.; Kukolich, S. G. Communications: Evidence for Proton Tunneling from the Microwave Spectrum of the Formic Acid-Propiolic Acid Dimer. J. Chem. Phys. 132, 2010, 201101/1. *Supported by the NSF CHE-1057796

  14. A large underestimate of the pyrogenic source of formic acid inferred from space-borne measurements.

    NASA Astrophysics Data System (ADS)

    Chaliyakunnel, S.; Millet, D. B.; Wells, K. C.; Cady-Pereira, K.; Shephard, M.

    2015-12-01

    Formic acid (HCOOH) is one of the most abundant carboxylic acids in the atmosphere, and a dominant source of acidity in the global troposphere. Recent work has revealed a major gap in our present understanding of the atmospheric formic acid budget, with observed concentrations much larger than can be reconciled with current estimates of its sources. In this work, we employ new space-based observations from the Tropospheric Emission Spectrometer (TES) satellite instrument with the GEOS-Chem chemical transport model to better quantify the source of atmospheric formic acid from biomass burning, and assess the degree to which this source can help close the large budget gap for this species. The space-based formic acid data reveal a severe model underestimate for HCOOH that is most prominent over tropical biomass burning regions, indicating a major missing source of organic acids from fires. Based on two independent methods for inferring the fractional contribution of fires to the measured HCOOH abundance, we find that the pyrogenic HCOOH:CO enhancement ratio measured by TES (including direct emissions plus secondary production) is 5-10 times higher than current estimates of the direct emission ratio, providing evidence of substantial secondary production of HCOOH in fire plumes. We further show that current models significantly underestimate (by a factor of 2-6) the total primary and secondary source of HCOOH from tropical fires.

  15. Carbon monoxide poisoning and pulmonary injury from the mixture of formic and sulfuric acids.

    PubMed

    Schneir, Aaron; Rentmeester, Landen

    2016-06-01

    The inhalation of carbon monoxide produced by the incomplete combustion of carbon remains a popular method of suicide. A much less common method of producing carbon monoxide for suicide is by mixing formic and sulfuric acids. We describe a patient who attempted suicide by mixing formic and sulfuric acids. He presented with a depressed level of consciousness, chemical burns of his airway and skin, and respiratory distress. He was found to have a metabolic acidosis, a carboxyhemoglobin of 36.8%, hyperkalemia, and rhabdomyolysis. His hospital course was notable for copious pulmonary secretions and hypoxia, but he ultimately recovered with supportive care. The case highlights the potential toxicity, particularly from inhaled carbon monoxide and formic acid, with this method of suicide.

  16. Facile synthesis of PtAu alloy nanoparticles with high activity for formic acid oxidation

    SciTech Connect

    Zhang, Sheng; Shao, Yuyan; Yin, Geping; Lin, Yuehe

    2010-02-15

    We report the facile synthesis of carbon supported PtAu alloy nanoparticles with high electrocatalytic activity as the anode catalyst for direct formic acid fuel cells (DFAFCs). PtAu alloy nanopaticles are synthesized by co-reducing HAuCl4 and H2PtCl6 with NaBH4 in the presence of sodium citrate and then the nanoparticles are deposited on Vulcan XC-72R carbon support (PtAu/C). The obtained catalysts are characterized with X-ray diffraction (XRD) and transmission electron microscope (TEM), which reveal PtAu alloy formation with an average diameter of 4.6 nm. PtAu/C exhibits 8 times higher catalytic activity toward formic acid oxidation than Pt/C. The enhanced activity of PtAu/C catalyst is attributed to noncontinuous Pt sites formed in the presence of the neighbored Au sites, which promotes direct oxidation of formic acid by avoiding poison CO.

  17. Formic acid interaction with the uranyl(VI) ion: structural and photochemical characterization.

    PubMed

    Lucks, Christian; Rossberg, André; Tsushima, Satoru; Foerstendorf, Harald; Fahmy, Karim; Bernhard, Gert

    2013-10-07

    Complex formation between the uranyl(VI) ion and formic acid was studied by infrared absorption (IR) and X-ray absorption (EXAFS) spectroscopy as well as density functional theory (DFT) calculations. In contrast to the acetate ion which forms exclusively a bidentate complex with uranyl(VI), the formate ion binds to uranyl(VI) in a unidentate fashion. The photochemistry of the uranyl(VI)-formic acid system was explored by DFT calculations and photoreduction of uranyl(VI) in the presence of formic acid was found to occur via an intermolecular process, that is, hydrogen abstraction from hydrogenformate by the photo-excited uranyl(VI). There is no photo-induced decarboxylation of uranyl(VI) formate via an intramolecular process, presumably due to lack of a C=C double bond.

  18. A new product with formic acid for Varroa jacobsoni Oud. control in Argentina. I. Efficacy.

    PubMed

    Eguaras, M; Del Hoyo, M; Palacio, M A; Ruffinengo, S; Bedascarrasbure, E L

    2001-02-01

    An organic product based on formic acid in a gel matrix was evaluated for use in Varroa control under autumnal climatic conditions in Argentina. Twenty colonies each received two gel packets with formic acid in two applications and numbers of falling mites were registered. After this treatment colonies received two other acaricides in order to compare efficacy. Average final efficacy in colonies treated with the organic product was 92% with a low variability. The gel matrix kept an adequate formic acid concentration inside the colonies with only two applications. This product is, therefore, a good alternative for Varroa control because it is organic, easy to use and presents a low variability in final efficacy between colonies. No queen, brood, or adult honeybee mortality was registered.

  19. Rotational Investigation of the Adducts of Formic Acid with Alcohols, Ethers and Esters

    NASA Astrophysics Data System (ADS)

    Evangelisti, Luca; Spada, Lorenzo; Li, Weixing; Caminati, Walther

    2016-06-01

    Mixtures of formic acid with methyl alcohol, with isopropyl alcohol, with tert-butyl alcohol, with dimethylether and with isopropylformiate have been supersonically expanded as pulsed jets. The obtained cool plumes have been analyzed by Fourier transform microwave spectroscopy. It has been possible to assign the rotational spectra of the 1:1 adducts of formic acid with tert-butyl alcohol, with dimethyl ether and with isopropylformiate. The conformational shapes and geometries of these adducts, as well as the topologies of their itermolecular hydrogen bonds will be presented. An explanation is given of the failure of the assignments of the rotational spectra of the adducts of formic acid with methyl alcohol and isopropyl alcohol.

  20. Conversion of coals with various degree of metamorphism in supercritical water with formic acid

    NASA Astrophysics Data System (ADS)

    Predtechensky, M. R.; Pukhovoy, M. V.; Smal, A. N.; Uuemaa, A. O.

    2007-09-01

    Conversion of coals with various degrees of metamorphism in supercritical water (SCW) was studied under the isochoric conditions at the temperatures of 380 800 °C. At conversion, formic acid, increasing the hydrogenating properties of the medium, was added into SCW. The results of conversion are comparable with the results of pyrolysis under the same temperatures. It was found that the degree of conversion in SCW is 10 15 % higher than that at pyrolysis. An addition of formic acid increases the conversion degree. After processing, there are almost no liquid organic substances escaped into SCW. However, some agglomerates, whose strength is comparable with the strength of lump coal, are formed because of dissolution of the organic matter in the mixture of SCW and formic acid.

  1. Pd nanoparticles supported on functionalized multi-walled carbon nanotubes (MWCNTs) and electrooxidation for formic acid

    NASA Astrophysics Data System (ADS)

    Yang, Sudong; Zhang, Xiaogang; Mi, Hongyu; Ye, Xiangguo

    To improve the utilization and activity of anodic catalysts for formic acid electrooxidation, palladium (Pd) particles were loaded on the MWCNTs, which were functionalized in a mixture of 96% sulfuric acid and 4-aminobenzenesulfonic acid, using sodium nitrite to produce intermediate diazonium salts from substituted anilines. The composition, particle size, and crystallinity of the Pd/f-MWCNTs catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) measurements. The electrocatalytic properties of the Pd/f-MWCNTs catalysts for formic acid oxidation were investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in 0.5 mol L -1 H 2SO 4 solution. The results demonstrated that the catalytic activity was greatly enhanced due to the improved water-solubility and dispersion of the f-MWCNTs, which were facile to make the small particle size (3.8 nm) and uniform dispersion of Pd particles loading on the surface of the MWCNTs. In addition, the functionalized MWCNTs with benzenesulfonic group can provide benzenesulfonic anions in aqueous solution, which may combine with hydrogen cation and then promote the oxidation of formic acid reactive intermediates. So the Pd/f-MWCNTs composites showed excellent electrocatalytic activity for formic acid oxidation.

  2. The electrochemical reduction of carbon dioxide to formate/formic acid: engineering and economic feasibility.

    PubMed

    Agarwal, Arun S; Zhai, Yumei; Hill, Davion; Sridhar, Narasi

    2011-09-19

    The engineering and economic feasibility of large-scale electrochemical reduction of carbon dioxide to formate salts and formic acid is the focus of this Full Paper. In our study we investigated the long-term performance of tin and other proprietary catalysts in the reduction of carbon dioxide to formate/formic acid at a gas/solid/liquid interface, using a flow-through reactor. The overall economics and energy consumption of the process are evaluated through a value chain analysis. The sensitivity of the net present value of the process to various process parameters is examined.

  3. A ruthenium-based biomimetic hydrogen cluster for efficient photocatalytic hydrogen generation from formic acid.

    PubMed

    Chang, Chin-Hao; Chen, Mei-Hua; Du, Wan-Shan; Gliniak, Jacek; Lin, Jia-Hoa; Wu, Hsin-Hua; Chan, Hsin-Fang; Yu, Jen-Shiang K; Wu, Tung-Kung

    2015-04-20

    A ruthenium-based biomimetic hydrogen cluster, [Ru2 (CO)6 (μ-SCH2 CH2 CH2 S)] (1), has been synthesized and, in the presence of the P ligand tri(o-tolyl)phosphine, demonstrated efficient photocatalytic hydrogen generation from formic acid decomposition. Turnover frequencies (TOFs) of 5500 h(-1) and turnover numbers (TONs) over 24 700 were obtained with less than 50 ppm of the catalyst, thus representing the highest TOFs for ruthenium complexes as well as the best efficiency for photocatalytic hydrogen production from formic acid. Moreover, 1 showed high stability with no significant degradation of the photocatalyst observed after prolonged photoirradiation at 90 °C.

  4. Oxidation mechanism of formic acid on the bismuth adatom-modified Pt(111) surface.

    PubMed

    Perales-Rondón, Juan Victor; Ferre-Vilaplana, Adolfo; Feliu, Juan M; Herrero, Enrique

    2014-09-24

    In order to improve catalytic processes, elucidation of reaction mechanisms is essential. Here, supported by a combination of experimental and computational results, the oxidation mechanism of formic acid on Pt(111) electrodes modified by the incorporation of bismuth adatoms is revealed. In the proposed model, formic acid is first physisorbed on bismuth and then deprotonated and chemisorbed in formate form, also on bismuth, from which configuration the C-H bond is cleaved, on a neighbor Pt site, yielding CO2. It was found computationally that the activation energy for the C-H bond cleavage step is negligible, which was also verified experimentally.

  5. Shape-dependent electrocatalytic activity of monodispersed palladium nanocrystals toward formic acid oxidation.

    PubMed

    Zhang, Xuwei; Yin, Huajie; Wang, Jinfeng; Chang, Lin; Gao, Yan; Liu, Wei; Tang, Zhiyong

    2013-09-21

    The catalytic activity of different-shaped and monodispersed palladium nanocrystals, including cubes, octahedra and rhombic dodecahedra, toward the electrochemical oxidation of formic acid has been systematically evaluated in both HClO4 and H2SO4 solutions. Notably, the cubic palladium nanocrystals wholly exposed with {100} facets exhibit the highest activity, while the rhombic dodecahedra with {110} facets show the lowest electrocatalytic performance. Furthermore, compared with HClO4 electrolyte, the catalytic activity is found to be obviously lower in H2SO4 solution likely due to the competitive adsorption of SO4(2-) ions and formic acid on the surface of Pd nanocrystals.

  6. Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media

    SciTech Connect

    King, R.B.; Bhattacharyya, N.K.; Wiemers, K.D.

    1994-08-01

    Simulants for the Hanford Waste Vitrification Plant (HWVP) feed containing the major non-radioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO{sub 3}{sup 2{minus}}, NO{sub 3}-, and NO{sub 2}- were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO{sub 2}H {yields} H{sub 2} + CO{sub 2} catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100{degree}C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO{sub 2}, H{sub 2}, NO, and N{sub 2}O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl{sub 3}{center_dot}3H{sub 2}O, was found to be the most active catalyst for hydrogen generation from formic acid above {approx}80{degree}C in the presence of nitrite ion in accord with earlier observations. The inherent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is suggested by the approximate pseudo first-order dependence of the hydrogen production rate on Rh concentration. Titration of the typical feed simulants containing carbonate and nitrite with formic acid in the presence of rhodium at the reaction temperature ({approx}90{degree}C) indicates that the nitrite-promoted Rh-catalyzed decomposition of formic acid occurs only after formic acid has reacted with all of the carbonate and nitrite present to form CO{sub 2} and NO/N{sub 2}O, respectively. The catalytic activities of Ru and Pd towards hydrogen generation from formic acid are quite different than those of Rh in that they are inhibited rather than promoted by the presence of nitrite ion.

  7. Hydrolysis of Ketene Catalyzed by Formic Acid: Modification of Reaction Mechanism, Energetics, and Kinetics with Organic Acid Catalysis

    SciTech Connect

    Louie, Matthew K.; Francisco, Joseph S.; Verdicchio, Marco; Klippenstein, Stephen J.; Sinha, Amitabha

    2015-05-14

    The hydrolysis of ketene (H2C=C=O) to form acetic acid involving two water molecules and also separately in the presence of one to two water molecules and formic acid (FA) was investigated. Our results show that, while the currently accepted indirect mechanism, involving addition of water across the carbonyl C=O bond of ketene to form an ene-diol followed by tautomerization of the ene-diol to form acetic acid, is the preferred pathway when water alone is present, with formic acid as catalyst, addition of water across the ketene C=C double bond to directly produce acetic acid becomes the kinetically favored pathway for temperatures below 400 K. We find not only that the overall barrier for ketene hydrolysis involving one water molecule and formic acid (H2C2O + H2O + FA) is significantly lower than that involving two water molecules (H2C2O + 2H(2)O) but also that FA is able to reduce the barrier height for the direct path, involving addition of water across the C=C double bond, so that it is essentially identical with (6.4 kcal/mol) that for the indirect ene-diol formation path involving addition of water across the C=O bond. For the case of ketene hydrolysis involving two water molecules and formic acid (H2C2O + 2H(2)O + FA), the barrier for the direct addition of water across the C=C double bond is reduced even further and is 2.5 kcal/mol lower relative to the ene-diol path involving addition of water across the C=O bond. In fact, the hydrolysis barrier for the H2C2O + 2H(2)O + FA reaction through the direct path is sufficiently low (2.5 kcal/mol) for it to be an energetically accessible pathway for acetic acid formation under atmospheric conditions. Given the structural similarity between acetic and formic acid, our results also have potential implications for aqueous-phase chemistry. Thus, in an aqueous environment, even in the absence of formic acid, though the initial mechanism for ketene hydrolysis is expected to involve addition of water across the carbonyl

  8. Microwave spectra and structure of the cyclopropanecarboxylic acid-formic acid dimer

    NASA Astrophysics Data System (ADS)

    Pejlovas, Aaron M.; Lin, Wei; Kukolich, Stephen G.

    2015-09-01

    The rotational spectrum of the cyclopropanecarboxylic acid-formic acid doubly hydrogen bonded dimer has been measured in the 4-11 GHz region using a Flygare-Balle type pulsed-beam Fourier transform microwave spectrometer. Rotational transitions were measured for the parent, four unique singly substituted 13C isotopologues, and a singly deuterated isotopologue. Splittings due to a possible concerted double proton tunneling motion were not observed. Rotational constants (A, B, and C) and centrifugal distortion constants (DJ and DJK) were determined from the measured transitions for the dimer. The values of the rotational (in MHz) and centrifugal distortion constants (in kHz) for the parent isotopologue are A = 4045.4193(16), B = 740.583 80(14), C = 658.567 60(23), DJ = 0.0499(16), and DJK = 0.108(14). A partial gas phase structure of the dimer was derived from the rotational constants of the measured isotopologues, previous structural work on each monomer units and results of the calculations.

  9. Improvement of electrocatalytic performance of carbon supported Pd anodic catalyst in direct formic acid fuel cell by ethylenediamine-tetramethylene phosphonic acid

    NASA Astrophysics Data System (ADS)

    Lu, Liang; Li, Huanzhi; Hong, Yujie; Luo, Yafen; Tang, Yawen; Lu, Tianhong

    2012-07-01

    The direct formic acid fuel cell (DFAFC) has two major shortcomings that limit its lifespan and performance: (i) the poor electrocatalytic stability of the carbon supported Pd (Pd/C) catalyst for the oxidation of formic acid and (ii) rapid decomposition of formic acid over the Pd/C catalyst. To solve the problems, the Pd/C catalyst is modified with ethylenediamine-tetramethylene phosphonic acid (EDTMP). The resulting catalyst is designated as Pd/C-E catalyst. It is found that the Pd/C-E catalyst can inhibit the decomposition of formic acid and promote the oxidation of formic acid through the direct pathway. Consistently, the Pd/C-E catalyst is significantly protected from CO poisoning. As compared to the Pd/C catalyst, the electrocatalytic performance of the Pd/C-E catalyst is significantly superior. These results provide the first proof of the concept that DFAFC can be significantly improved by Pd/C-E catalyst.

  10. Influence of sodium carbonate on decomposition of formic acid by pulsed discharge plasma inside bubble in water

    NASA Astrophysics Data System (ADS)

    Iwabuchi, Masashi; Takahashi, Katsuyuki; Takaki, Koichi; Satta, Naoya

    2016-07-01

    The influence of sodium carbonate on the decomposition of formic acid by discharge inside bubbles in water was investigated experimentally. Oxygen or argon gases were injected into the water through a vertically positioned glass tube, in which the high-voltage wire electrode was placed to generate plasmas at low applied voltage. The concentration of formic acid was determined by ion chromatography. In the case of sodium carbonate additive, the pH increased owing to the decomposition of the formic acid. In the case of oxygen injection, the percentage of conversion of formic acid increased with increasing pH because the reaction rate of ozone with formic acid increased with increasing pH. In the case of argon injection, the percentage of conversion was not affected by the pH owing to the high rate loss of hydroxyl radicals.

  11. Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

    SciTech Connect

    Lee, H.; Habas, S.E.; Somorjai, G.A.; Yang, P.

    2008-03-20

    Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for the investigation of electrocatalytic formic acid oxidation. The binary particles exhibited much less self-poisoning and a lower activation energy relative to Pt nanocubes, consistent with the single crystal study.

  12. Photoassisted enhancement of the electrocatalytic oxidation of formic acid on platinized TiO₂ nanotubes.

    PubMed

    Mojumder, Nazrul; Sarker, Swagotom; Abbas, Syed Arslan; Tian, Zong; Subramanian, Vaidyanathan Ravi

    2014-04-23

    A solvothermal method is used to deposit Pt nanoparticles on anodized TiO2 nanotubes (T_NT). Surface characterization using SEM, EDX, and XRD indicates the formation of polycrystalline TiO2 nanotubes of 110 ± 10 nm diameter with Pt nanoparticle islands. The application of the T_NT/Pt photoanode has been examined toward simultaneous electrooxidation and photo(electro)oxidation of formic acid (HCOOH). Upon UV-vis photoillumination, the T_NT/Pt photoelectrode generates a current density of 72 mA/cm(2), which is significantly higher (∼39-fold) than that of the T_NT electrode (1.85 mA/cm(2)). This boosting in the overall current is attributable to the enhanced oxidation of formic acid at the T_NT/Pt-electrolyte interface. Further, a series of cyclic voltammetric (CV) responses, of which each anodic scan is switched to photoillumination at a certain applied bias (i.e., 0.2 V, 0.4 V, etc.), is used to identify the role of T_NT/Pt as a promoter for the photoelectrooxidation of formic acid and understand a carbon monoxide (CO)-free pathway. Chronoamperometric (j/t) measurements demonstrate the evidence of an external bias dependent variation in the time lag during the current stabilization. An analysis of the CV plots and j/t profiles suggests the existence of both the charge-transfer controlled process and the diffusion-controlled process during formic acid photoelectrooxidation.

  13. Characterization and formic acid oxidation studies of PtAu nanoparticles.

    PubMed

    Saipanya, Surin; Srisombat, Laongnuan; Wongtap, Pitak; Sarakonsri, Thapanee

    2014-10-01

    Characterization and electrocatalytic oxidation of formic acid on PtAu nanoparticles supported multiwalled carbon nanotube (MWCNT) were studied. Electrochemical measurements were conducted in a self-made conventional three-electrode glass cell at room temperature. A Pt wire and Ag/AgCl were used as auxiliary and reference electrodes, respectively. The Pt was electrodeposited onto the electrode and their catalytic activities in the electrooxidation of formic acid were examined and compared. The morphology and composition were studied by a combination of transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Cyclic voltamograms of formic acid electrooxidation show a distinguishing shape with a prominent oxidation peak in the forward scan contributed to the formic acid oxidation whilst the backward scan is associated with the oxidation of exclusion of carbonaceous species. On the basis of the onset potential and current density, the resulting PtAu nanoparticles showed much higher electrocatalytic activity than other counterparts. The results show an excellent sign of applications for fuel cell.

  14. High performance Pd-based catalysts for oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Wang, Rongfang; Liao, Shijun; Ji, Shan

    Two novel catalysts for anode oxidation of formic acid, Pd 2Co/C and Pd 4Co 2Ir/C, were prepared by an organic colloid method with sodium citrate as a complexing agent. These two catalysts showed better performance towards the anodic oxidation of formic acid than Pd/C catalyst and commercial Pt/C catalyst. Compared with Pd/C catalyst, potentials of the anodic peak of formic acid at the Pd 2Co/C and Pd 4Co 2Ir/C catalyst electrodes shifted towards negative value by 140 and 50 mV, respectively, meanwhile showed higher current densities. At potential of 0.05 V (vs. SCE), the current density for Pd 4Co 2Ir/C catalyst is as high as up to 13.7 mA cm -2, which is twice of that for Pd/C catalyst, and six times of that for commercial Pt/C catalyst. The alloy catalysts were nanostructured with a diameter of ca. 3-5 nm and well dispersed on carbon according to X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The composition of alloy catalysts was analyzed by energy dispersive X-ray analysis (EDX). Pd 4Co 2Ir/C catalyst showed the highest activity and best stability making it the best potential candidate for application in a direct formic acid fuel cell (DFAFC).

  15. Mesoporous vanadium nitride as a high performance catalyst support for formic acid electrooxidation.

    PubMed

    Yang, Minghui; Cui, Zhiming; DiSalvo, Francis J

    2012-11-04

    Mesoporous vanadium nitride (VN) with high surface area and good electrical conductivity was prepared by a solid-solid phase separation method from a Zn containing vanadium oxide, Zn(3)V(2)O(8). The VN supported Pd catalyst exhibited significant catalytic activity for formic acid oxidation.

  16. Length tunable penta-twinned palladium nanorods: seedless synthesis and electrooxidation of formic acid.

    PubMed

    Tang, Yongan; Edelmann, Richard E; Zou, Shouzhong

    2014-06-07

    Palladium nanorods with controlled lengths from 100 to 500 nm and a fixed width of 20 nm were synthesized for the first time by a seedless approach. These rods show higher peak current densities than Pd cubes for formic acid oxidation and the catalytic activity decreases with increasing rod length.

  17. Localized Pd overgrowth on cubic Pt nanocrystals for enhanced electrocatalytic oxidation of formic acid.

    PubMed

    Lee, Hyunjoo; Habas, Susan E; Somorjai, Gabor A; Yang, Peidong

    2008-04-23

    Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for the investigation of electrocatalytic formic acid oxidation. The binary particles exhibited much less self-poisoning and a lower activation energy relative to Pt nanocubes, consistent with the single crystal study.

  18. Shape-dependent electrocatalytic activity of monodispersed palladium nanocrystals toward formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Xuwei; Yin, Huajie; Wang, Jinfeng; Chang, Lin; Gao, Yan; Liu, Wei; Tang, Zhiyong

    2013-08-01

    The catalytic activity of different-shaped and monodispersed palladium nanocrystals, including cubes, octahedra and rhombic dodecahedra, toward the electrochemical oxidation of formic acid has been systematically evaluated in both HClO4 and H2SO4 solutions. Notably, the cubic palladium nanocrystals wholly exposed with {100} facets exhibit the highest activity, while the rhombic dodecahedra with {110} facets show the lowest electrocatalytic performance. Furthermore, compared with HClO4 electrolyte, the catalytic activity is found to be obviously lower in H2SO4 solution likely due to the competitive adsorption of SO42- ions and formic acid on the surface of Pd nanocrystals.The catalytic activity of different-shaped and monodispersed palladium nanocrystals, including cubes, octahedra and rhombic dodecahedra, toward the electrochemical oxidation of formic acid has been systematically evaluated in both HClO4 and H2SO4 solutions. Notably, the cubic palladium nanocrystals wholly exposed with {100} facets exhibit the highest activity, while the rhombic dodecahedra with {110} facets show the lowest electrocatalytic performance. Furthermore, compared with HClO4 electrolyte, the catalytic activity is found to be obviously lower in H2SO4 solution likely due to the competitive adsorption of SO42- ions and formic acid on the surface of Pd nanocrystals. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03100d

  19. Glycerol-plasticised silk membranes made using formic acid are ductile, transparent and degradation-resistant.

    PubMed

    Allardyce, Benjamin J; Rajkhowa, Rangam; Dilley, Rodney J; Redmond, Sharon L; Atlas, Marcus D; Wang, Xungai

    2017-11-01

    Regenerated silk fibroin membranes tend to be brittle when dry. The use of plasticisers such as glycerol improve membrane ductility, but, when combined with aqueous processing, can lead to a higher degradation rate than solvent-annealed membranes. This study investigated the use of formic acid as the solvent with glycerol to make deformable yet degradation-resistant silk membranes. Here we show that membranes cast using formic acid had low light scattering, with a diffuse transmittance of less than 5% over the visible wavelengths, significantly lower than the 20% transmittance of aqueous derived silk/glycerol membranes. They had 64% β-sheet content and lost just 30% of the initial silk weight over 6h when tested with an accelerated enzymatic degradation assay, in comparison the aqueous membranes completely degraded within this timeframe. The addition of glycerol also improved the maximum elongation of formic acid derived membranes from under 3% to over 100%. They also showed good cytocompatibility and supported the adhesion and migration of human tympanic membrane keratinocytes. Formic acid based, silk/glycerol membranes may be of great use in medical applications such as repair of tympanic membrane perforation or ocular applications where transparency and resistance to enzymatic degradation are important. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. 40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance with... AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD...

  1. Wood ants produce a potent antimicrobial agent by applying formic acid on tree-collected resin.

    PubMed

    Brütsch, Timothée; Jaffuel, Geoffrey; Vallat, Armelle; Turlings, Ted C J; Chapuisat, Michel

    2017-04-01

    Wood ants fight pathogens by incorporating tree resin with antimicrobial properties into their nests. They also produce large quantities of formic acid in their venom gland, which they readily spray to defend or disinfect their nest. Mixing chemicals to produce powerful antibiotics is common practice in human medicine, yet evidence for the use of such "defensive cocktails" by animals remains scant. Here, we test the hypothesis that wood ants enhance the antifungal activity of tree resin by treating it with formic acid. In a series of experiments, we document that (i) tree resin had much higher inhibitory activity against the common entomopathogenic fungus Metarhizium brunneum after having been in contact with ants, while no such effect was detected for other nest materials; (ii) wood ants applied significant amounts of endogenous formic and succinic acid on resin and other nest materials; and (iii) the application of synthetic formic acid greatly increased the antifungal activity of resin, but had no such effect when applied to inert glass material. Together, these results demonstrate that wood ants obtain an effective protection against a detrimental microorganism by mixing endogenous and plant-acquired chemical defenses. In conclusion, the ability to synergistically combine antimicrobial substances of diverse origins is not restricted to humans and may play an important role in insect societies.

  2. Formic Acid Investigation for the Prediction of High Explosive Detonation Properties and Performance

    DTIC Science & Technology

    2010-07-01

    release; distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The JAGUAR EXP-6 parameters of formic acid were originally optimized by...PETN), and were later modified to reproduce experimental overdriven detonation pressures. The resulting parameters are employed in the JAGUAR ... JAGUAR was subsequently demonstrated to provide accurate detonation properties for wide ranges of conditions including the C-J state, overdriven

  3. Divergent modulation of swine ileal microbiota by formic acid and methionine hydroxy analogue-free acid.

    PubMed

    Apajalahti, J; Rademacher, M; Htoo, J K; Redshaw, M; Kettunen, A

    2009-06-01

    Management of intestinal microbiota of monogastric animals has increased in importance since the ban of growth promoting antibiotics in many countries. Organic acids have been used as alternatives to antibiotics by many feed manufacturers. Regardless of the wide usage, the effect, dose response and mode of action of acids on intestinal microbes is poorly understood. In this study, we investigated the effects of dietary supplementation of three commonly used products, namely formic acid (FA) (90%), dl-methionine (DLM) (99%) and liquid methionine hydroxy analogue-free acid (88%), on ileal microbiota of pigs. Laboratory simulation system, mimicking swine ileum, was used to study the products at various concentrations and combinations. Furthermore, selected combinations were tested in a piglet trial to confirm the findings made in in vitro studies. FA turned out to have a dual effect on ileal microbiota. At concentrations below 0.5%, it significantly stimulated bacteria, but at higher inclusion rates it was highly inhibitory. This finding, which was consistent in in vitro and in vivo studies, implies that reducing the dose of FA does not lead to a diluted inhibitory effect, but in fact, an opposite, stimulatory effect on intestinal microbiota. It is highly important that feed compounders acknowledge this finding. Unlike FA, the inhibitory effect of methionine hydroxy analogue on ileal bacteria was linearly dose dependent and significant at inclusion levels above 0.2%, in vitro. Partial replacement of methionine hydroxy analogue by FA, or FA by methionine hydroxy analogue, led to an unpredictable outcome due to the dual effects of FA; e.g., a minor inclusion of added FA changed the inhibitory effect of methionine hydroxy analogue into microbial stimulation by FA. Inhibition of ileal microbiota by methionine hydroxy analogue was detected only in in vitro studies, suggesting that intact methionine hydroxy analogue may not have reached the ileum, in live animals. Therefore

  4. Microwave measurements of proton tunneling and structural parameters for the propiolic acid-formic acid dimer.

    PubMed

    Daly, Adam M; Douglass, Kevin O; Sarkozy, Laszlo C; Neill, Justin L; Muckle, Matt T; Zaleski, Daniel P; Pate, Brooks H; Kukolich, Stephen G

    2011-10-21

    Microwave spectra of the propiolic acid-formic acid doubly hydrogen bonded complex were measured in the 1 GHz to 21 GHz range using four different Fourier transform spectrometers. Rotational spectra for seven isotopologues were obtained. For the parent isotopologue, a total of 138 a-dipole transitions and 28 b-dipole transitions were measured for which the a-dipole transitions exhibited splittings of a few MHz into pairs of lines and the b-type dipole transitions were split by ~580 MHz. The transitions assigned to this complex were fit to obtain rotational and distortion constants for both tunneling levels: A(0+) = 6005.289(8), B(0+) = 930.553(8), C(0+) = 803.9948(6) MHz, Δ(0+)(J) = 0.075(1), Δ(0+)(JK) = 0.71(1), and δ(0+)(j) = -0.010(1) kHz and A(0-) = 6005.275(8), B(0-) = 930.546(8), C(0-) = 803.9907(5) MHz, Δ(0-)(J) = 0.076(1), Δ(0-)(JK) = 0.70(2), and δ(0-)(j) = -0.008(1) kHz. Double resonance experiments were used on some transitions to verify assignments and to obtain splittings for cases when the b-dipole transitions were difficult to measure. The experimental difference in energy between the two tunneling states is 291.428(5) MHz for proton-proton exchange and 3.35(2) MHz for the deuterium-deuterium exchange. The vibration-rotation coupling constant between the two levels, F(ab), is 120.7(2) MHz for the proton-proton exchange. With one deuterium atom substituted in either of the hydrogen-bonding protons, the tunneling splittings were not observed for a-dipole transitions, supporting the assignment of the splitting to the concerted proton tunneling motion. The spectra were obtained using three Flygare-Balle type spectrometers and one chirped-pulse machine at the University of Virginia. Rotational constants and centrifugal distortion constants were obtained for HCOOH···HOOCCCH, H(13)COOH···HOOCCCH, HCOOD···HOOCCCH, HCOOH···DOOCCCH, HCOOD···DOOCCCH, DCOOH···HOOCCCH, and DCOOD···HOOCCCH. High-level ab initio calculations provided

  5. Microwave measurements of proton tunneling and structural parameters for the propiolic acid-formic acid dimer

    NASA Astrophysics Data System (ADS)

    Daly, Adam M.; Douglass, Kevin O.; Sarkozy, Laszlo C.; Neill, Justin L.; Muckle, Matt T.; Zaleski, Daniel P.; Pate, Brooks H.; Kukolich, Stephen G.

    2011-10-01

    Microwave spectra of the propiolic acid-formic acid doubly hydrogen bonded complex were measured in the 1 GHz to 21 GHz range using four different Fourier transform spectrometers. Rotational spectra for seven isotopologues were obtained. For the parent isotopologue, a total of 138 a-dipole transitions and 28 b-dipole transitions were measured for which the a-dipole transitions exhibited splittings of a few MHz into pairs of lines and the b-type dipole transitions were split by ˜580 MHz. The transitions assigned to this complex were fit to obtain rotational and distortion constants for both tunneling levels: A0+ = 6005.289(8), B0+ = 930.553(8), C0+ = 803.9948(6) MHz, Δ0+J = 0.075(1), Δ0+JK = 0.71(1), and δ0+j = -0.010(1) kHz and A0- = 6005.275(8), B0- = 930.546(8), C0- = 803.9907(5) MHz, Δ0-J = 0.076(1), Δ0-JK = 0.70(2), and δ0-j = -0.008(1) kHz. Double resonance experiments were used on some transitions to verify assignments and to obtain splittings for cases when the b-dipole transitions were difficult to measure. The experimental difference in energy between the two tunneling states is 291.428(5) MHz for proton-proton exchange and 3.35(2) MHz for the deuterium-deuterium exchange. The vibration-rotation coupling constant between the two levels, Fab, is 120.7(2) MHz for the proton-proton exchange. With one deuterium atom substituted in either of the hydrogen-bonding protons, the tunneling splittings were not observed for a-dipole transitions, supporting the assignment of the splitting to the concerted proton tunneling motion. The spectra were obtained using three Flygare-Balle type spectrometers and one chirped-pulse machine at the University of Virginia. Rotational constants and centrifugal distortion constants were obtained for HCOOH...HOOCCCH, H13COOH...HOOCCCH, HCOOD...HOOCCCH, HCOOH...DOOCCCH, HCOOD...DOOCCCH, DCOOH...HOOCCCH, and DCOOD...HOOCCCH. High-level ab initio calculations provided initial rotational constants for the complex, structural

  6. Simultaneous airborne nitric acid and formic acid measurements using a chemical ionization mass spectrometer around the UK: Analysis of primary and secondary production pathways

    NASA Astrophysics Data System (ADS)

    Le Breton, Michael; Bacak, Asan; Muller, Jennifer B. A.; Xiao, Ping; Shallcross, Beth M. A.; Batt, Rory; Cooke, Michael C.; Shallcross, Dudley E.; Bauguitte, S. J.-B.; Percival, Carl J.

    2014-02-01

    The first simultaneous measurements of formic and nitric acid mixing ratios around the United Kingdom were measured on the FAAM BAe-146 research aircraft with a chemical ionization mass spectrometer using I- reagent ions at 0.8 Hz. Analysis of the whole dataset shows that formic acid and nitric acid are positively correlated as illustrated by other studies (e.g. Veres et al., 2011). However, initial evidence indicates a prominent direct source of formic acid and also a significant source when O3 levels are high, suggesting the importance of the ozonolysis of 1-alkenes. A trajectory model was able to reproduce the formic acid concentrations by both the inclusion of a primary vehicle source and production via ozonolysis of propene equivalent 1-alkene levels. Inspection of data archives implies these levels of 1-alkene are possible after 11 am, but formic acid and nitric acid plumes early in the flight are too high for the model to replicate. These data show the relationship between nitric acid and formic acid cannot solely be attributed to related photochemical production. The simultaneous measurement of HCOOH and HNO3 has been implemented to estimate OH levels along the flight track assuming a relationship between formic and nitric acid in photochemical plumes and a constant source of 1-alkene.

  7. Microwave spectra and structure of the cyclopropanecarboxylic acid-formic acid dimer

    SciTech Connect

    Pejlovas, Aaron M.; Kukolich, Stephen G.; Lin, Wei

    2015-09-28

    The rotational spectrum of the cyclopropanecarboxylic acid–formic acid doubly hydrogen bonded dimer has been measured in the 4-11 GHz region using a Flygare-Balle type pulsed-beam Fourier transform microwave spectrometer. Rotational transitions were measured for the parent, four unique singly substituted {sup 13}C isotopologues, and a singly deuterated isotopologue. Splittings due to a possible concerted double proton tunneling motion were not observed. Rotational constants (A, B, and C) and centrifugal distortion constants (D{sub J} and D{sub JK}) were determined from the measured transitions for the dimer. The values of the rotational (in MHz) and centrifugal distortion constants (in kHz) for the parent isotopologue are A = 4045.4193(16), B = 740.583 80(14), C = 658.567 60(23), D{sub J} = 0.0499(16), and D{sub JK} = 0.108(14). A partial gas phase structure of the dimer was derived from the rotational constants of the measured isotopologues, previous structural work on each monomer units and results of the calculations.

  8. Formic and acetic acid over the central Amazon region, Brazil 1. Dry season

    SciTech Connect

    Andreae, M.O.; Talbot, R.W.; Andreae, T.W.; Harriss, R.C.

    1988-02-20

    We have determined the atmospheric concentrations of formic and acetic acid in the gas phase, in aerosols, and in rain during the dry season (July--August 1985) in the Amazonia region of Brazil. At ground level the average concentrations of gas phase formic and acetic acid were 1.6 +- 0.6 and 2.2 +- 1.0 ppb, respectively. The diurnal behavior of both acids at ground level and their vertical distribution in the forest canopy point to the existence of vegetative sources as well as to production by chemical reactions in the atmosphere. Dry deposition of the gaseous acids appears to be a major sink. The concentrations of formic and acetic acid in the gas phase were about 2 orders of magnitude higher than concentrations of the corresponding species in the atmospheric aerosol. About 50--60%/sub 0/ of the aerosol (total) formate and acetate were in the size fraction below 1.0 ..mu..m diameter.

  9. Dynamics of Low Energy Electron Attachment to Formic Acid

    SciTech Connect

    Rescigno, Thomas N.; Trevisan, Cynthia S.; Orel, Ann E.

    2006-04-03

    Low-energy electrons (<2 eV) can fragment gas phaseformic acid (HCOOH) molecules through resonant dissociative attachmentprocesses. Recent experiments have shown that the principal reactionproducts of such collisions are formate ions (HCOO-) and hydrogen atoms.Using first-principles electron scattering calculations, we haveidentified the responsible negative ion state as a transient \\pi* anion.Symmetry considerations dictate that the associated dissociation dynamicsare intrinsically polyatomic: a second anion surface, connected to thefirst by a conical intersection, is involved in the dynamics and thetransient anion must necessarily deform to non-planar geometries beforeit can dissociate to the observed stable products.

  10. The effects of lactic acid bacteria inoculants and formic acid on the formation of biogenic amines in grass silages.

    PubMed

    Steidlová, S; Kalac, P

    2004-06-01

    Silages were prepared in six laboratory experiments from four direct-cut grassland swards and pure swards of perennial ryegrass and false oat with dry matter contents ranging between 180 and 325 g/kg. Grass was fermented at 22 degrees C and silages were stored at the same temperature for 4 months. Untreated silages (negative control) and silages preserved with 3 g/kg of formic acid (positive control) were compared with silages inoculated with commercial strains of Lactobacillus plantarum, Lactobacillus buchneri and a mixed preparation Microsil. The inoculants were applied at a dose of 5.10(6) CFU/g of grass. Seven biogenic amines were extracted from silages with perchloric acid and determined as N-benzamides by micellar electrokinetic capillary chromatography. Common chemical quality parameters of silages were also determined. Tyramine, cadaverine and putrescine were the amines occurring at the highest concentration. As compared to untreated silages, formic acid was most effective to suppress formation of the main amines. Also the inoculants often decreased amine contents significantly (P < 0.05). The inoculants decreased levels of polyamine spermidine more efficiently than formic acid. Contents of histamine, tryptamine and polyamine spermine were very low, commonly below the detection limits.

  11. Chirped Pulse and Cavity FT Microwave Spectroscopy of the Formic Acid - Trimethylamine Weakly Bound Complex

    NASA Astrophysics Data System (ADS)

    Mackenzie, Becca; Dewberry, Chris; Leopold, Ken

    2015-06-01

    Amine-carboxylic acid interactions are important in many biological systems and have recently received attention for their role in the formation of atmospheric aerosols. Here, we study the molecular and electronic structure of the formic acid - trimethylamine complex, using it as a model for amine-carboxylic acid interactions. The microwave spectrum of the complex has been observed using chirped pulse and conventional cavity-type Fourier transform microwave spectroscopy. The degree of proton transfer has been assessed using the 14N nuclear quadrupole hyperfine structure. Experimental results will be compared to DFT calculations.

  12. Importance of direct anthropogenic emissions of formic acid measured by a chemical ionisation mass spectrometer (CIMS) during the Winter ClearfLo Campaign in London, January 2012

    NASA Astrophysics Data System (ADS)

    Bannan, Thomas J.; Bacak, Asan; Muller, Jennifer B. A.; Booth, A. Murray; Jones, Benjamin; Le Breton, Michael; Leather, Kimberley E.; Ghalaieny, Mohamed; Xiao, Ping; Shallcross, Dudley E.; Percival, Carl J.

    2014-02-01

    Formic acid, an ubiquitous trace gas in the atmosphere, was measured using a chemical ionisation mass spectrometer (CIMS) during the winter ClearfLo campaign in London, 2012. Daily calibrations of formic acid gave sensitivities of 3 ion counts s-1 pptv-1 for the complete campaign and a limit of detection of 2 ppt. No correlation with nitric acid was observed, R2 of 0.137, indicating no significant secondary source of formic acid. However, a strong positive correlation with NOx, CO, and production in line with rush hour periods indicated a direct anthropogenic emission of formic acid from vehicle emissions. Peaks of 6.7 ppb of formic acid were observed with a mean of 610 ppt. Global models indicated that this emission source dominates in the northern hemisphere where global models underestimate formic acid most significantly, thus increasing the accuracy of modelling of global formic acid emissions.

  13. Application of normal pulse voltammetry to the kinetic study of formic acid oxidation on a carbon supported Pd electrocatalyst

    NASA Astrophysics Data System (ADS)

    Wang, Yujiao; Wu, Xiaochen; Wu, Bing; Gao, Ying

    The kinetic parameters of formic acid oxidation on a carbon supported Pd electrode, such as the charge transfer coefficient (α) and apparent diffusion coefficient (D) are obtained by applying the technique of normal pulse voltammetry. The standard rate constant (k 0) of formic acid oxidation on a Pd/C electrode is estimated. The results show that formic acid oxidation is more sensitive to temperature at relatively high potential because the activation energy is significantly increased as the potential rose above 0.6 V.

  14. Photoelectrochemical behavior of nanostructured WO3 thin-film electrodes: The oxidation of formic acid.

    PubMed

    Monllor-Satoca, Damián; Borja, Luis; Rodes, Antonio; Gómez, Roberto; Salvador, Pedro

    2006-12-11

    Nanostructured tungsten trioxide thin-film electrodes are prepared on conducting glass substrates by either potentiostatic electrodeposition from aqueous solutions of peroxotungstic acid or direct deposition of WO3 slurries. Once treated thermally in air at 450 degrees C, the electrodes are found to be composed of monoclinic WO3 grains with a particle size around 30-40 nm. The photoelectrochemical behavior of these electrodes in 1 M HClO4 apparently reveals a low degree of electron-hole recombination. Upon addition of formic acid, the electrode showed the current multiplication phenomenon together with a shift of the photocurrent onset potential toward less positive values. Photoelectrochemical experiments devised on the basis of a kinetic model reported recently [I. Mora-Seró, T. Lana-Villarreal, J. Bisquert, A. Pitarch, R. Gómez, P. Salvador, J. Phys. Chem. B 2005, 109, 3371] showed that an interfacial mechanism of inelastic, direct hole transfer takes place in the photooxidation of formic acid. This behavior is attributed to the tendency of formic acid molecules to be specifically adsorbed on the WO3 nanoparticles, as evidenced by attenuated total reflection infrared spectroscopy.

  15. Decadal variations of rainwater formic and acetic acid concentrations in Wilmington, NC, USA

    NASA Astrophysics Data System (ADS)

    Willey, Joan D.; Glinski, Donna A.; Southwell, Melissa; Long, Michael S.; Avery, G. Brooks, Jr.; Kieber, Robert J.

    2011-02-01

    Concentrations of formic and acetic acid from January 2008 through March 2009 were compared to two previous studies at this location (conducted in 1987-1990 and 1996-1998) in order to quantify the extent to which temporal changes in DOC and pH can be explained by changes in these organic acids. The volume weighted 2008 formic and acetic acid concentrations (5.6 and 2.6 μM respectively) have decreased dramatically compared with those observed during the 1996-1998 study (9.9 and 7.3 μM) and are also lower than concentrations observed in the 1987-1990 study (7.4 and 3.6 μM). Changes in formic and acetic acids between 1996-97 and 2008 can account for approximately 50% of the DOC change and 40% of the H + change in rainwater over this same time period. These changes are most pronounced during the growing season, which is also the tourist and high traffic season at this location. Determining causation of these changes is difficult due to multiple biogenic and anthropogenic sources. However, the ratio of formic to acetic acid has also reverted back to a value consistent with reduced vehicular emissions, possibly related to the introduction of improved emission control technology including the use of reformulated gasoline in the late 1990's. Long term monitoring of seasonal, annual, and decadal trends will be of critical importance for evaluating the effects of future changes to atmospheric inputs such as the increased use of ethanol and other alternative fuels.

  16. Dehydrogenation of Formic Acid Catalyzed by a Ruthenium Complex with an N,N'-Diimine Ligand.

    PubMed

    Guan, Chao; Zhang, Dan-Dan; Pan, Yupeng; Iguchi, Masayuki; Ajitha, Manjaly J; Hu, Jinsong; Li, Huaifeng; Yao, Changguang; Huang, Mei-Hui; Min, Shixiong; Zheng, Junrong; Himeda, Yuichiro; Kawanami, Hajime; Huang, Kuo-Wei

    2017-01-03

    We report a ruthenium complex containing an N,N'-diimine ligand for the selective decomposition of formic acid to H2 and CO2 in water in the absence of any organic additives. A turnover frequency of 12 000 h(-1) and a turnover number of 350 000 at 90 °C were achieved in the HCOOH/HCOONa aqueous solution. Efficient production of high-pressure H2 and CO2 (24.0 MPa (3480 psi)) was achieved through the decomposition of formic acid with no formation of CO. Mechanistic studies by NMR and DFT calculations indicate that there may be two competitive pathways for the key hydride transfer rate-determining step in the catalytic process.

  17. Butylphenyl-functionalized Pt nanoparticles as CO-resistant electrocatalysts for formic acid oxidation.

    PubMed

    Zhou, Zhi-You; Ren, Jie; Kang, Xiongwu; Song, Yang; Sun, Shi-Gang; Chen, Shaowei

    2012-01-28

    Butylphenyl-functionalized Pt nanoparticles (Pt-BP) with an average core diameter of 2.93 ± 0.49 nm were synthesized by the co-reduction of butylphenyl diazonium salt and H(2)PtCl(4). Cyclic voltammetric studies of the Pt-BP nanoparticles showed a much less pronounced hysteresis between the oxidation currents of formic acid in the forward and reverse scans, as compared to that on naked Pt surfaces. Electrochemical in situ FTIR studies confirmed that no adsorbed CO, a poisoning intermediate, was generated on the Pt-BP nanoparticle surface. These results suggest that functionalization of the Pt nanoparticles by butylphenyl fragments effectively blocked the CO poisoning pathway, most probably through third-body effects, and hence led to an apparent improvement of the electrocatalytic activity in formic acid oxidation.

  18. Electrons Mediate the Gas-Phase Oxidation of Formic Acid with Ozone.

    PubMed

    van der Linde, Christian; Tang, Wai-Kit; Siu, Chi-Kit; Beyer, Martin K

    2016-08-26

    Gas-phase reactions of CO3 (.-) with formic acid are studied using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Signal loss indicates the release of a free electron, with the formation of neutral reaction products. This is corroborated by adding traces of SF6 to the reaction gas, which scavenges 38 % of the electrons. Quantum chemical calculations of the reaction potential energy surface provide a reaction path for the formation of neutral carbon dioxide and water as the thermochemically favored products. From the literature, it is known that free electrons in the troposphere attach to O2 , which in turn transfer the electron to O3 . O3 (.-) reacts with CO2 to form CO3 (.-) . The reaction reported here formally closes the catalytic cycle for the oxidation of formic acid with ozone, catalyzed by free electrons. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Adsorbed formate: the key intermediate in the oxidation of formic acid on platinum electrodes.

    PubMed

    Cuesta, Angel; Cabello, Gema; Gutiérrez, Claudio; Osawa, Masatoshi

    2011-12-07

    The electrooxidation of formic acid on Pt and other noble metal electrodes proceeds through a dual-path mechanism, composed of a direct path and an indirect path through adsorbed carbon monoxide, a poisoning intermediate. Adsorbed formate had been identified as the reactive intermediate in the direct path. Here we show that actually it is also the intermediate in the indirect path and is, hence, the key reaction intermediate, common to both the direct and indirect paths. Furthermore, it is confirmed that the dehydration of formic acid on Pt electrodes requires adjacent empty sites, and it is demonstrated that the reaction follows an apparently paradoxical electrochemical mechanism, in which an oxidation is immediately followed by a reduction.

  20. Length tunable penta-twinned palladium nanorods: seedless synthesis and electrooxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Tang, Yongan; Edelmann, Richard E.; Zou, Shouzhong

    2014-05-01

    Palladium nanorods with controlled lengths from 100 to 500 nm and a fixed width of 20 nm were synthesized for the first time by a seedless approach. These rods show higher peak current densities than Pd cubes for formic acid oxidation and the catalytic activity decreases with increasing rod length.Palladium nanorods with controlled lengths from 100 to 500 nm and a fixed width of 20 nm were synthesized for the first time by a seedless approach. These rods show higher peak current densities than Pd cubes for formic acid oxidation and the catalytic activity decreases with increasing rod length. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00299g

  1. Pd oxides/hydrous oxides as highly efficient catalyst for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Yan, Liang; Yao, Shikui; Chang, Jinfa; Liu, Changpeng; Xing, Wei

    2014-03-01

    A novel Pd-based catalyst for formic acid electrooxidation (FAEO) was prepared by annealing commercial Pd/C catalyst under the O2 atmosphere at 100 °C, which exhibits excellent catalytic activity and stability for FAEO due to introduction of Pd oxides/hydrous oxides (POHOs). The catalytic activity of the as-prepared catalyst towards FAEO is 1.86 times of the commercial Pd/C catalyst in 0.5 M H2SO4 + 0.5 M HCOOH solution. Chronoamperometric curves show obvious improvement of the as-prepared catalyst electrocatalytic stability for FAEO. It is confirmed that POHOs can provide the required oxygen species for intermediate CO oxidation during the oxidation process of formic acid.

  2. Carbon nanofiber supported bimetallic PdAu nanoparticles for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Qin, Yuan-Hang; Jiang, Yue; Niu, Dong-Fang; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2012-10-01

    Carbon nanofiber (CNF) supported PdAu nanoparticles are synthesized with sodium citrate as the stabilizing agent and sodium borohydride as the reducing agent. High resolution transmission electron microscopy (HRTEM) characterization indicates that the synthesized PdAu particles are well dispersed on the CNF surface and X-ray diffraction (XRD) characterization indicates that the alloying degree of the synthesized PdAu nanoparticles can be improved by adding tetrahydrofuran to the synthesis solution. The results of electrochemical characterization indicate that the addition of Au can promote the electrocatalytic activity of Pd/C catalyst for formic acid oxidation and the CNF supported high-alloying PdAu catalyst possesses better electrocatalytic activity and stability for formic acid oxidation than either the CNF supported low-alloying PdAu catalyst or the CNF supported Pd catalyst.

  3. Synthesis and assembly of Pd nanoparticles on graphene for enhanced electrooxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Jin, Tao; Guo, Shaojun; Zuo, Jing-Lin; Sun, Shouheng

    2012-12-01

    Monodisperse 4.5 nm Pd nanoparticles (NPs) were synthesized by solution phase reduction of palladium acetylacetonate with morpholine borane in a mixture of oleylamine and 1-octadecene. These NPs were assembled on graphene uniformly in the form of a monolayer, and showed much enhanced catalysis for electrooxidation of formic acid. The work demonstrates the great potential of graphene as a support to enhance NP catalysis and stability for important chemical oxidation reactions.Monodisperse 4.5 nm Pd nanoparticles (NPs) were synthesized by solution phase reduction of palladium acetylacetonate with morpholine borane in a mixture of oleylamine and 1-octadecene. These NPs were assembled on graphene uniformly in the form of a monolayer, and showed much enhanced catalysis for electrooxidation of formic acid. The work demonstrates the great potential of graphene as a support to enhance NP catalysis and stability for important chemical oxidation reactions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr33060a

  4. La2O3 Promoted Pd/rGO Electro-catalysts for Formic Acid Oxidation.

    PubMed

    Ali, Hassan; Kanodarwala, Fehmida K; Majeed, Imran; Stride, John Arron; Nadeem, Muhammad Arif

    2016-11-30

    High activity, a low rate of CO poisoning, and long-term stability of Pd electro-catalysts are necessary for practical use as an anode material in direct formic acid fuel cells. Achieving a high degree of Pd nanoparticle dispersion on a carbon support, without agglomeration, while maintaining a facile electron transfer through the catalyst surface are two challenging tasks to be overcome in fulfilling this aim. Herein, we report the effect of addition of La/La-oxides on the efficiency of Pd nanoparticles supported on reduced graphene oxide (rGO) for formic acid electro-oxidation reaction. A series of electro-catalysts with different Pd-La molar ratios were successfully synthesized and characterized using a range of techniques including PXRD, XPS, TEM, FTIR, and Raman spectroscopy and then tested as anode materials for direct formic acid fuel cells. We explore that the lanthanum species (La/La-oxide) significantly promote the activity and stability of Pd catalyst toward electrocatalytic oxidation of formic acid. The metallic ratio is found to be critical, and the activity order of various catalysts is observed as follows; Pd30La70/rGO > Pd80La20/rGO > Pd70La30 rGO. The obtained mass specific activity for Pd30La70/rGO (986.42 A/g) is 2.18 times higher than that for Pd/rGO (451 A/g) and 16 times higher than that for Pd/C (61.5 A/g) at given onset peak potentials. The high activity and stability of the electro-catalysts are attributed to the uniform dispersion of Pd nanoparticles over the rGO support, as evidenced from TEM images. It is believed that the role of La species in promoting the catalyst activity is to disperse the catalyst particles during synthesis and to facilitate the electron transfer via providing a suitable pathway during electrochemical testing.

  5. "Raisin bun"-like nanocomposites of palladium clusters and porphyrin for superior formic acid oxidation.

    PubMed

    Wang, Xiuxin; Yang, Jiandong; Yin, Huajie; Song, Rui; Tang, Zhiyong

    2013-05-21

    A novel "raisin bun"-like nanocomposite, where Pd clusters are embedded in porphyrin matrix, is developed as a promising electrocatalyst. Thanks to the synergy between the Pd clusters and the porphyrin matrix, this composite exhibits a low oxidation potential, high mass activity and excellent stability toward electrochemical oxidation of formic acid, which opens new routes for the design of high-performance catalysts in fuel cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Synthesis and assembly of Pd nanoparticles on graphene for enhanced electrooxidation of formic acid.

    PubMed

    Jin, Tao; Guo, Shaojun; Zuo, Jing-lin; Sun, Shouheng

    2013-01-07

    Monodisperse 4.5 nm Pd nanoparticles (NPs) were synthesized by solution phase reduction of palladium acetylacetonate with morpholine borane in a mixture of oleylamine and 1-octadecene. These NPs were assembled on graphene uniformly in the form of a monolayer, and showed much enhanced catalysis for electrooxidation of formic acid. The work demonstrates the great potential of graphene as a support to enhance NP catalysis and stability for important chemical oxidation reactions.

  7. Formic acid-based treatments for control of Varroa destructor in a Mediterranean area.

    PubMed

    Satta, Alberto; Floris, Ignazio; Eguaras, Martin; Cabras, Paolo; Garau, Vincenzo Luigi; Melis, Marinella

    2005-04-01

    Two formic acid autumnal treatments, gel packets (BeeVar formulation) and impregnated paperwick (Liebig-Dispenser), were tested in apiary to evaluate their effectiveness against Varroa destructor Anderson & Trueman and their residues in honey in a Mediterranean region (Sardinia, Italy). Both treatments were efficient in the apiary control of the varroosis, with values of percentage of mite mortality ranging between 93.6 and 100%, without statistical differences between them. The more gradual release of formic acid from the gel application allowed a longer action (2 wk for each treatment) compared with the Liebig-Dispenser (approximately 3d for each treatment). The rate of daily evaporation ranged between approximately 5 and 9 g/d from BeeVar and approximately 26 and 35 g/d from the Liebig-Dispenser, in the first and second treatment, respectively. The total amount of formic acid administered per hive during all the treatment period was approximately 200 g for either treatment. A significantly higher adult bee mortality was recorded in the Liebig-Dispenser-treated hives compared with the BeeVar-treated group. On the contrary, BeeVar treatment produced an interruption of brood reared, whereas the extension of the sealed brood area of the Liebig-Dispenser-treated hives was not significantly different from that of the control hives. Neither queen mortality nor robbing activity was observed due to the treatments. Formic acid residues in honey collected in the nest were 3,855 +/- 2,061 and 3,030 +/- 1,624 mg/kg for the BeeVar- and the Liebig-Dispenser-treated hives, respectively. After 21 d from the end of the treatment, the residues fell to 1,261 +/- 1,054 and 794 +/- 518 mg/kg for the honey sampled from the BeeVar and Liebig-Dispenser groups, respectively.

  8. Photo-oxidation of Acetone to Formic Acid in Synthetic Air and Its Atmospheric Implication.

    PubMed

    Chattopadhyay, Aparajeo; Chatterjee, Piyali; Chakraborty, Tapas

    2015-07-23

    Acetone photo-oxidation in synthetic air under exposure of 311 nm ultraviolet light has been studied, and the photo-oxidation products are identified by means of infrared spectroscopy. Analysis reveals that formic acid is one of the major products, although there have been debates in the past concerning the authenticity of formation of this acid in synthetic air via the photo-oxidation pathway. The quantum yield of formation of this acid is similar to that of other major photoproducts like methanol, formaldehyde, and carbon monoxide. The reaction yield, however, decreases with an increase in total air pressure in the reaction cell, but it is still significant at pressures relevant to tropospheric conditions. A kinetic model has been used to simulate the measured reaction kinetics, and the quantum yields predicted by the model are found to be consistent with the measured yields for different durations of light exposure. The same model has also been used to investigate the effect of atmospheric nitric oxide on the fate of formation of this acid in the troposphere. Although nitric oxide is known to be a quencher of peroxy radicals, the precursors of formaldehyde and formic acid in acetone photo-oxidation, but our model predicts that this oxide plays a positive role in the overall reaction kinetics for production of this acid in the troposphere.

  9. Microwave-assisted 18O-labeling of proteins catalyzed by formic acid.

    PubMed

    Liu, Ning; Wu, Hanzhi; Liu, Hongxia; Chen, Guonan; Cai, Zongwei

    2010-11-01

    Oxygen exchange may occur at carboxyl groups catalyzed by acid. The reaction, however, takes at least several days at room temperature. The long-time exchanging reaction often prevents its application from protein analysis. In this study, an (18)O-labeling method utilizing microwave-assisted acid hydrolysis was developed. After being dissolved in (16)O/(18)O (1:1) water containing 2.5% formic acid, protein samples were exposed to microwave irradiation. LC-MS/MS analysis of the resulted peptide mixtures indicated that oxygen in the carboxyl groups from glutamic acid, aspartic acid, and the C-terminal residues could be efficiently exchanged with (18)O within less than 15 min. The rate of back exchange was so slow that no detectable back exchange could be found during the HPLC run.

  10. CO2 Hydrogenation to Formic Acid on Ni(111)

    SciTech Connect

    Peng, Guowen; Sibener, S. J.; Schatz, George C.; Ceyer, Sylvia T.; Mavrikakis, Manos

    2011-12-26

    Periodic, self-consistent, density functional theory (DFT) calculations are employed to study CO2 hydrogenation on Ni(111). CO2 hydrogenation with H adsorbed on the surface and with H absorbed in the subsurface is investigated systematically, and the respective microscopic reaction mechanisms are elucidated. We show that on Ni(111) CO2 hydrogenation to formate intermediate is more favorable than to carboxyl intermediate. The hydrogenation to formate goes through the unidentate structure that rapidly transforms into the bidentate structure. Further hydrogenation from formate to formic acid is energetically more difficult than formate formation. Formation of adsorbed formic acid from adsorbed CO2 and surface hydrogen is an endothermic reaction. Because subsurface H in Ni(111) is substantially less stable compared to surface H, its reaction with adsorbed CO2 to adsorbed formic acid is an exothermic one. Finally, our results may have significant implications for the synthesis of liquid fuels from CO2 and for catalytic hydrogenation reactions in general.

  11. Electrocatalytic oxidation of formic acid and formaldehyde on nanoparticle decorated single walled carbon nanotubes.

    PubMed

    Selvaraj, V; Grace, A Nirmala; Alagar, M

    2009-05-01

    A potent catalyst has been prepared consisting of platinum (Pt), and platinum-palladium (Pt-Pd) nanoparticles supported on purified single-walled carbon nanotubes (Pt/CNT and Pt-Pd/CNT). Electrochemical characteristics of formic acid and formaldehyde oxidation on these catalysts are investigated via cyclic voltammetric analysis in mixed 0.5 M HCOOH (or 0.5 M HCHO) and 0.5 M H(2)SO(4) solutions. The results imply that the Pt-Pd/CNT electrodes exhibit a better activity than the corresponding Pt nanoparticles modified SWCNT electrodes. The modified electrode exhibits significant electrocatalytic activity towards formic acid and formaldehyde oxidation, which may be attributed due to the uniform dispersion of nanoparticles on SWCNTs and the efficacy of Pd species in Pt-Pd system. Such nanoparticles modified CNT electrodes exhibit better catalytic behavior towards formic acid and formaldehyde than the corresponding carbon electrodes, indicating that the system studied in the present work is the more promising system for use in fuel cells.

  12. Structural effects of electrochemical oxidation of formic acid on single crystal electrodes of palladium.

    PubMed

    Hoshi, Nagahiro; Kida, Kaori; Nakamura, Masashi; Nakada, Miou; Osada, Kazuhito

    2006-06-29

    Structural effects on the rates of formic acid oxidation have been studied on Pd(111), Pd(100), Pd(110), and Pd(S)-[n(100) x (111)] (n = 2-9) electrodes in 0.1 M HClO4 containing 0.1 M formic acid with use of voltammetry. On the low index planes of Pd, the maximum current density of formic acid oxidation (jP) increases in the positive scan as follows: Pd(110) < Pd(111) < Pd(100). This order differs from that on the low index planes of Pt: Pt(111) < Pt(100) < Pt(110). Pd(S)-[n(100) x (111)] electrodes with terrace atomic rows n > or = 3 have almost the same jP as Pd(100), except Pd(911) n = 5. The value of jP on Pd(911) n = 5 is 20% higher than those of the other surfaces. Pd(311) n = 2, of which the first layer is composed of only step atoms, has the lowest jP in the Pd(S)-[n(100) x (111)] series. The adsorption geometry of the reaction intermediate (formate ion) is optimized by using density functional theory.

  13. Enhancement of anodic oxidation of formic acid on palladium decorated Pt/C catalyst

    NASA Astrophysics Data System (ADS)

    Wu, Yan Ni; Liao, Shi Jun; Su, Yun Lan; Zeng, Jian Huang; Dang, Dai

    A palladium decorated Pt/C catalyst, Pt@Pd/C, is prepared by a colloidal approach with a small amount of platinum as core. It is found that the catalyst shows excellent activity towards anodic oxidation of formic acid at room temperature and its activity is 60% higher than that of Pd/C. Decoration of palladium shell on the platinum core is supported by XPS results. Due to the use of platinum as core, active components are dispersed very well and the particle sizes are smaller than those of Pd/C. The cyclic voltammetry measurement clearly shows synthetic electro-oxidation effects of formic acid on Pt@Pd/C. It is speculated that the high performance of Pt@Pd/C may result from the unique core-shell structure and synergistic effect of Pt and Pd at the interface. The preparation method for Pt@Pd/C reported in this work will provide additional options for the design of catalysts for direct formic acid fuel cell (DFAFC).

  14. Electrocatalysis of formic acid on palladium and platinum surfaces: from fundamental mechanisms to fuel cell applications.

    PubMed

    Jiang, Kun; Zhang, Han-Xuan; Zou, Shouzhong; Cai, Wen-Bin

    2014-10-14

    Formic acid as a natural biomass and a CO2 reduction product has attracted considerable interest in renewable energy exploitation, serving as both a promising candidate for chemical hydrogen storage material and a direct fuel for low temperature liquid fed fuel cells. In addition to its chemical dehydrogenation, formic acid oxidation (FAO) is a model reaction in the study of electrocatalysis of C1 molecules and the anode reaction in direct formic acid fuel cells (DFAFCs). Thanks to a deeper mechanistic understanding of FAO on Pt and Pd surfaces brought about by recent advances in the fundamental investigations, the "synthesis-by-design" concept has become a mainstream idea to attain high-performance Pt- and Pd-based nanocatalysts. As a result, a large number of efficient nanocatalysts have been obtained through different synthesis strategies by tailoring geometric and electronic structures of the two primary catalytic metals. In this paper, we provide a brief overview of recent progress in the mechanistic studies of FAO, the synthesis of novel Pd- and Pt-based nanocatalysts as well as their practical applications in DFAFCs with a focus on discussing studies significantly contributing to these areas in the past five years.

  15. N-doped graphene-supported binary PdBi networks for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Yan, Bo; Zhang, Ke; Wang, Jin; Li, Shumin; Wang, Caiqin; Du, Yukou; Yang, Ping; Jiang, Shujuan; Song, Shaoqing

    2017-09-01

    As advanced electrodes for direct formic acid cells, nitrogen-doped graphene (NG) supported palladium-bismuth nanoparticles have been successfully fabricated through typical wet-chemical method. In studying the effects of NG support on PdBi nanoparticles for the electrooxidation of formic acid, we find that the as-prepared Pd1Bi1/NG network-like electrocatalysts exhibit much higher electrocatalytic activities than the Pd1Bi1/RGO, Pd1Bi1 and commercially available Pd/C catalysts in term of mass activity (1.69, 4.33 and 15.5times higher, respectively). The remarkably enhanced performances are associated with the electron transport between Bi and N, bi-functional effect between Pd, Bi and NG hybrids as well as the well-dispersed network-like structure on the surface of NG. The investigations of PdBi/NG in this work for promoting the electrocatalytic performances and the electron effect between Bi and N will accelerate the development for the field of direct formic acid fuel cells.

  16. Formic acid aided hot water extraction of hemicellulose from European silver birch (Betula pendula) sawdust.

    PubMed

    Goldmann, Werner Marcelo; Ahola, Juha; Mikola, Marja; Tanskanen, Juha

    2017-05-01

    Hemicellulose has been extracted from birch (Betula pendula) sawdust by formic acid aided hot water extraction. The maximum amount of hemicellulose extracted was about 70mol% of the total hemicellulose content at 170°C, measured as the combined yield of xylose and furfural. Lower temperatures (130 and 140°C) favored hemicellulose hydrolysis rather than cellulose hydrolysis, even though the total hemicellulose yield was less than at 170°C. It was found that formic acid greatly increased the hydrolysis of hemicellulose to xylose and furfural at the experimental temperatures. The amount of lignin in the extract remained below the detection limit of the analysis (3g/L) in all cases. Formic acid aided hot water extraction is a promising technique for extracting hemicellulose from woody biomass, while leaving a solid residue with low hemicellulose content, which can be delignified to culminate in the three main isolated lignocellulosic fractions: cellulose, hemicellulose, and lignin. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Ultra-uniform PdBi nanodots with high activity towards formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Zhang, Ke; Yan, Bo; Wang, Jin; Wang, Caiqin; Li, Shumin; Gu, Zhulan; Du, Yukou; Yang, Ping

    2017-07-01

    Tuning the morphology and compositions of catalyst is an effective method for promoting electrocatalytic intrinsic activity. However, many newly-generated nanocrystals with better nanostructures often have a large size, which enforces them to display extremely limited surface area and ultimately lead to the limited electrocatalytic activity. To break this bottleneck, we herein report a facile and reproducible wet-chemical method to control the synthesis of a class of ultra-uniform and small PdBi nanodots endowed with both high surface areas and tunable compositions. The presented PdBi nanodots show the ultrasmall size (ca.2.5 nm) and great uniform dispersion property. These significant characteristics enable them to exhibit unprecedented electrocatalytic activities and durability toward formic acid oxidation. The mass activity and electrochemical surface active (ECSA) of prepared PdBi nanodots for the formic acid oxidation is 8.9/3.75 times higher than that of commercial Pd/C, respectively. We speculate that both of this facile synthetic approach and remarkable electrocatalytic performance of the obtained catalysts in this work illustrate that they can be applied as a promising catalyst for direct formic acid cells.

  18. Processing of formic acid-containing ice by heavy and energetic cosmic ray analogues

    NASA Astrophysics Data System (ADS)

    Bergantini, A.; Pilling, S.; Rothard, H.; Boduch, P.; Andrade, D. P. P.

    2014-01-01

    Formic acid (HCOOH) has been extensively detected in space environments, including interstellar medium (gas and grains), comets and meteorites. Such environments are often subjected to the action of ionizing agents, which may cause changes in the molecular structure, thus leading to formation of new species. Formic acid is a possible precursor of pre-biotic species, such as Glycine (NH2CH2COOH). This work investigates experimentally the physicochemical effects resulting from interaction of heavy and energetic cosmic ray analogues (46 MeV 58Ni11 +) in H2O:HCOOH (1:1) ice, at 15 K, in ultrahigh vacuum regime, using Fourier transform infrared spectrometry in the mid-infrared region (4000-600 cm-1 or 2.5-12.5 μm). After the bombardment, the sample was slowly heated to room temperature. The results show the dissociation cross-section for the formic acid of 2.4 × 10-13 cm2, and half-life due to galactic cosmic rays of ˜8 × 107 yr. The IR spectra show intense formation of CO and CO2, and small production of more complex species at high fluences.

  19. Trends in Formic Acid Decomposition on Model Transition Metal Surfaces: A Density Functional Theory Study

    SciTech Connect

    Herron, Jeffrey A.; Scaranto, Jessica; Ferrin, Peter A.; Li, Sha; Mavrikakis, Manos

    2014-12-05

    We present a first-principles, self-consistent periodic density functional theory (PW91-GGA) study of formic acid (HCOOH) decomposition on model (111) and (100) facets of eight fcc metals (Au, Ag, Cu, Pt, Pd, Ni, Ir, and Rh) and (0001) facets of four hcp (Co, Os, Ru, and Re) metals. The calculated binding energies of key formic acid decomposition intermediates including formate (HCOO), carboxyl (COOH), carbon monoxide (CO), water (H2O), carbon dioxide (CO2), hydroxyl (OH), carbon (C), oxygen (O), and hydrogen (H; H2) are presented. Using these energetics, we develop thermochemical potential energy diagrams for both the carboxyl-mediated and the formate-mediated dehydrogenation mechanisms on each surface. We evaluate the relative stability of COOH, HCOO, and other isomeric intermediates (i.e., CO + OH, CO2 + H, CO + O + H) on these surfaces. These results provide insights into formic acid decomposition selectivity (dehydrogenation versus dehydration), and in conjunction with calculated vibrational frequency modes, the results can assist with the experimental search for the elusive carboxyl (COOH) surface intermediate. Results are compared against experimental reports in the literature.

  20. Dissociative Recombination of Protonated Formic Acid: Implications for Molecular Cloud and Cometary Chemistry

    NASA Astrophysics Data System (ADS)

    Vigren, E.; Hamberg, M.; Zhaunerchyk, V.; Kaminska, M.; Semaniak, J.; Larsson, M.; Thomas, R. D.; Ugglas, M. af; Kashperka, I.; Millar, T. J.; Walsh, C.; Roberts, H.; Geppert, W. D.

    2010-02-01

    At the heavy ion storage ring CRYRING in Stockholm, Sweden, we have investigated the dissociative recombination of DCOOD+ 2 at low relative kinetic energies, from ~1 meV to 1 eV. The thermal rate coefficient has been found to follow the expression k(T) = 8.43 × 10-7 (T/300)-0.78 cm3 s-1 for electron temperatures, T, ranging from ~10 to ~1000 K. The branching fractions of the reaction have been studied at ~2 meV relative kinetic energy. It has been found that ~87% of the reactions involve breaking a bond between heavy atoms. In only 13% of the reactions do the heavy atoms remain in the same product fragment. This puts limits on the gas-phase production of formic acid, observed in both molecular clouds and cometary comae. Using the experimental results in chemical models of the dark cloud, TMC-1, and using the latest release of the UMIST Database for Astrochemistry improves the agreement with observations for the abundance of formic acid. Our results also strengthen the assumption that formic acid is a component of cometary ices.

  1. Formic acid production using a microbial electrolysis desalination and chemical-production cell.

    PubMed

    Lu, Yaobin; Luo, Haiping; Yang, Kunpeng; Liu, Guangli; Zhang, Renduo; Li, Xiao; Ye, Bo

    2017-06-13

    The aim of this study was to investigate the feasibility and optimization of formic acid production in the microbial electrolysis desalination and chemical-production cell (MEDCC). The maximum current density in the MEDCC with 72cm of the anode fiber length (72-MEDCC) reached 24.0±2.0A/m(2), which was much higher than previously reported. The maximum average formic acid production rate in the 72-MEDCC was 5.28 times higher than that in the MEDCC with 24cm of the anode fiber length (37.00±1.15vs. 7.00±0.25mg/h). High performance in the 72-MEDCC was attributed to small membrane spacing (1mm), high flow rate (1500μL/min) on the membrane surface and high anode biomass. The minimum electricity consumption of 0.34±0.04kWh/kg in the 72-MEDCC was only 3.1-18.8% of those in the EDBMs. The MEDCC should be a promising technology for the formic acid production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Highly active Pt3Pb and core-shell Pt3Pb-Pt electrocatalysts for formic acid oxidation.

    PubMed

    Kang, Yijin; Qi, Liang; Li, Meng; Diaz, Rosa E; Su, Dong; Adzic, Radoslav R; Stach, Eric; Li, Ju; Murray, Christopher B

    2012-03-27

    Formic acid is a promising chemical fuel for fuel cell applications. However, due to the dominance of the indirect reaction pathway and strong poisoning effects, the development of direct formic acid fuel cells has been impeded by the low activity of existing electrocatalysts at desirable operating voltage. We report the first synthesis of Pt(3)Pb nanocrystals through solution phase synthesis and show they are highly efficient formic acid oxidation electrocatalysts. The activity can be further improved by manipulating the Pt(3)Pb-Pt core-shell structure. Combined experimental and theoretical studies suggest that the high activity from Pt(3)Pb and the Pt-Pb core-shell nanocrystals results from the elimination of CO poisoning and decreased barriers for the dehydrogenation steps. Therefore, the Pt(3)Pb and Pt-Pb core-shell nanocrystals can improve the performance of direct formic acid fuel cells at desired operating voltage to enable their practical application. © 2012 American Chemical Society

  3. Three-dimensionally ordered mesoporous Pd networks templated by a silica super crystal and their application in formic acid electrooxidation.

    PubMed

    Ye, Lin; Wang, Yu; Chen, Xueying; Yue, Bin; Tsang, Shik Chi; He, Heyong

    2011-07-14

    Three-dimensionally ordered mesoporous Pd networks fabricated by a simple reduction method in solution using a face centered cubic silica super crystal as template exhibit high electroactivity in formic acid oxidation.

  4. Ternary Pd2/PtFe networks supported by 3D graphene for efficient and durable electrooxidation of formic acid.

    PubMed

    Hu, Chuangang; Zhao, Yang; Cheng, Huhu; Hu, Yue; Shi, Gaoquan; Dai, Liming; Qu, Liangti

    2012-12-18

    A newly-designed network of ternary Pd(2)/PtFe nanowires on a three-dimensional graphene framework has been fabricated via a dual solvothermal approach, which presents superior electrocatalytic activity towards the oxidation of formic acid.

  5. Incorporation and/or adduction of formic acid with DNA in vivo studied by HPLC-AMS

    NASA Astrophysics Data System (ADS)

    Zhu, Jiadan; Cheng, Yan; Sun, Hongfang; Wang, Haifang; Li, Yuankai; Liu, Yuanfang; Ding, Xingfang; Fu, Dongpo; Liu, Kexin; Wang, Deqing; Deng, Xiaoyong

    2010-04-01

    The contribution of incorporation and/or adduction of formic acid with liver DNA in mouse was investigated using accelerator mass spectrometry (AMS) associated with high performance liquid chromatography (HPLC). Four kinds of 5'-formylated adducts, which were prepared by the reaction of formic acid and deoxyribonucleosides in vitro, were used as references for the HPLC-AMS analysis of in vivo adduction. After the administration of sodium 14C-formate to mice, the liver DNA pellets were isolated and enzymatically digested to deoxyribonucleosides. A precise analysis of the hydrolysate by HPLC-AMS indicates that a majority of formic acid incorporates directly into DNA, whereas less than 1.5% might form instable formylated DNA adducts in vivo. The results greatly support the important perspective that formic acid is not carcinogenic. Moreover, this study demonstrates that a combination of HPLC with AMS is an essential means for the evaluation of DNA adduction.

  6. Evaluation of Hanford high level waste vitrification chemistry for an NCAW simulant -- FY 1994: Potential exothermic reactions in the presence of formic acid, glycolic acid, and oxalic acid

    SciTech Connect

    Sills, J.A.

    1995-07-01

    A potential for an uncontrollable exothermic reaction between nitrate and organic salts during preparation of a high level waste melter feed has been identified. In order to examine this potential more closely, the thermal behavior of simulated neutralized current acid waste (NCAW) treated with various organic reductants was studied. Differential scanning calorimetry (DSC) measurements were collected on simulated waste samples and their supernates treated with organics. Organic reductants used were formic acid, glycolic acid, and oxalic acid. For comparison, samples of untreated simulant and untreated simulant with added noble metals were tested. When heated, untreated simulant samples both with and without noble metals showed no exothermic behavior. All of the treated waste simulant samples showed exothermic behavior. Onset temperatures of exothermic reactions were 120 C to 210 C. Many onset temperatures, particularly those for formic acid treated samples, are well below 181 C, the estimated maximum steam coil temperature (considered to be a worst case maximum temperature for chemical process tank contents). The enthalpies of the reactions were {minus}180 {times} 10{sup {minus}3} J/Kg supernate ({minus}181 J/g) for the oxalic acid treated simulant supernate to {minus}1,150 {times} 10{sup {minus}3} J/Kg supernate ({minus}1,153 J/g) for the formic acid treated simulant supernate.

  7. Oleylamine-mediated synthesis of Pd nanoparticles for catalytic formic acid oxidation.

    PubMed

    Mazumder, Vismadeb; Sun, Shouheng

    2009-04-08

    We report a facile synthesis of monodisperse Pd nanoparticles by the reduction of Pd(acac)(2) with oleylamine and borane tributylamine complex. The oleylamine-coated Pd nanoparticles are readily "cleaned" with a 99% acetic acid wash, and the Pd particles supported on Ketjen carbon are catalytically active for formic acid oxidation in HClO(4) solution. The catalyst shows no obvious activity degradation after 1500 cyclic voltammetry cycles under ambient conditions. These Pd particles hold promise as a highly active non-Pt catalyst for fuel cell applications.

  8. Photooxidation of cyclohexanone in simulated atmosphere: A potential source of atmospheric formic acid

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Aparajeo; Mondal, Koushik; Samanta, Monoj; Chakraborty, Tapas

    2017-05-01

    Gas phase photooxidation of cyclohexanone (CH) has been studied in the laboratory in a simulated atmospheric environment (synthetic air, 1 bar pressure) under the exposure of 311 nm UV light. Formic acid along with formaldehyde and ethylene are identified as the major photooxidation products. Quantum yield for the production of these species is measured and the values are compared with previous studies on the photo dissociation of CH. For 6 h of light irradiation with initial CH concentration of 9.19 ± 0.1 × 1016 molecules cm-3, the measured quantum yield values of ethylene and formaldehyde, the two primary photooxidation products, are 0.0395 ± 0.001 and 0.0028 ± 0.002, respectively. These values are comparable with CH dissociation quantum yield, 0.24 ± 0.02, and also the quantum yield of CO production, 0.0940 ± 0.001. The energetic parameters of different steps of the proposed reaction mechanism are calculated by electronic structure theory method at DFT/B3LYP/6-311++G** level. A reaction modeling has been performed, and similarity in simulated quantum yield values with that of the experimentally measured ones validates the suggested reaction mechanism. Experimentally measured values of rate constants of most of the elementary reaction steps incorporated in the modeling are not known, and the calculated values, obtained by use of CVT and RRKM theoretical methods are used. The total yield of formic acid, which has been assigned as a secondary oxidation product, is 3.46 ± 0.25 × 1015 molecules cm-3 as obtained from experiment and this data matches well with the value of 2.67 × 1015 molecules cm-3 obtained from reaction modeling for 6 h of UV irradiation. The yield of formic acid is comparable with the yield of primary photo products. The results imply that photooxidation of CH and analogous compounds might have significant contributions to production of formic acid in the earth's troposphere. According to the prediction of the modeling results presented

  9. Formic and acetic acid over the central Amazon region, Brazil. I - Dry season

    NASA Technical Reports Server (NTRS)

    Andreae, M. O.; Andreae, T. W.; Talbot, R. W.; Harriss, R. C.

    1988-01-01

    The concentrations of formic and acetic acids in the gas phase, atmospheric aerosol, and rainwater samples collected in Amazonia at ground level and in the atmosphere during the Amazon Boundary Layer Experiment in July/August 1985 were analyzed by ion exchange chromatography. The diurnal behavior of both acids at ground level and their vertical distribution in the forest canopy point to the existence of vegetative sources as well as to production by chemical reactions in the atmosphere. The concentrations of formic and acetic acids in the gas phase were about 2 orders of magnitude higher than the corresponding concentrations in the atmospheric aerosol. In rainwater, the total formate and acetate represented about one half of the anion equivalents, in contrast to less than 10 percent of the soluble anionic equivalents contributed by these acids in the atmospheric aerosol. The observed levels of these ions in rainwater are considered to be the result of a combination of chemical reactions in hydrometeors and the scavenging of the gaseous acids by cloud droplets.

  10. Formic and acetic acid over the central Amazon region, Brazil. I - Dry season

    NASA Technical Reports Server (NTRS)

    Andreae, M. O.; Andreae, T. W.; Talbot, R. W.; Harriss, R. C.

    1988-01-01

    The concentrations of formic and acetic acids in the gas phase, atmospheric aerosol, and rainwater samples collected in Amazonia at ground level and in the atmosphere during the Amazon Boundary Layer Experiment in July/August 1985 were analyzed by ion exchange chromatography. The diurnal behavior of both acids at ground level and their vertical distribution in the forest canopy point to the existence of vegetative sources as well as to production by chemical reactions in the atmosphere. The concentrations of formic and acetic acids in the gas phase were about 2 orders of magnitude higher than the corresponding concentrations in the atmospheric aerosol. In rainwater, the total formate and acetate represented about one half of the anion equivalents, in contrast to less than 10 percent of the soluble anionic equivalents contributed by these acids in the atmospheric aerosol. The observed levels of these ions in rainwater are considered to be the result of a combination of chemical reactions in hydrometeors and the scavenging of the gaseous acids by cloud droplets.

  11. Kinetic and stoichiometric characterization of organoautotrophic growth of Ralstonia eutropha on formic acid in fed-batch and continuous cultures.

    PubMed

    Grunwald, Stephan; Mottet, Alexis; Grousseau, Estelle; Plassmeier, Jens K; Popović, Milan K; Uribelarrea, Jean-Louis; Gorret, Nathalie; Guillouet, Stéphane E; Sinskey, Anthony

    2015-01-01

    Formic acid, acting as both carbon and energy source, is a safe alternative to a carbon dioxide, hydrogen and dioxygen mix for studying the conversion of carbon through the Calvin-Benson-Bassham (CBB) cycle into value-added chemical compounds by non-photosynthetic microorganisms. In this work, organoautotrophic growth of Ralstonia eutropha on formic acid was studied using an approach combining stoichiometric modeling and controlled cultures in bioreactors. A strain deleted of its polyhydroxyalkanoate production pathway was used in order to carry out a physiological characterization. The maximal growth yield was determined at 0.16 Cmole Cmole(-1) in a formate-limited continuous culture. The measured yield corresponded to 76% to 85% of the theoretical yield (later confirmed in pH-controlled fed-batch cultures). The stoichiometric study highlighted the imbalance between carbon and energy provided by formic acid and explained the low growth yields measured. Fed-batch cultures were also used to determine the maximum specific growth rate (μmax  = 0.18 h(-1) ) and to study the impact of increasing formic acid concentrations on growth yields. High formic acid sensitivity was found in R eutropha since a linear decrease in the biomass yield with increasing residual formic acid concentrations was observed between 0 and 1.5 g l(-1) .

  12. Unraveling the Role of Formic Acid and the Type of Solvent in the Catalytic Conversion of Lignin: A Holistic Approach.

    PubMed

    Oregui-Bengoechea, Mikel; Gandarias, Inaki; Arias, Pedro L; Barth, Tanja

    2017-02-22

    The role of formic acid together with the effect of the solvent type and their synergic interactions with a NiMo catalyst were studied for the conversion of lignin into bio-oil in an alcohol/formic acid media. The replacement of formic acid with H2 or isopropanol decreased the oil yield to a considerable degree, increased the solid yield, and altered the nature of the bio-oil. The differences induced by the presence of H2 were comparable to those observed in the isopropanol system, which suggests similar lignin conversion mechanisms for both systems. Additional semi-batch experiments confirmed that formic acid does not act merely as an in situ hydrogen source or hydrogen donor molecule. Actually, is seems to react with lignin through a formylation-elimination-hydrogenolysis mechanism that leads to the depolymerization of the biopolymer. This reaction competes with formic acid decomposition, which gives mainly H2 and CO2 , and forms a complex reaction system. To the best of our knowledge, this is the first time that the distinctive role/mechanism of formic acid has been observed in the conversion of real lignin feedstock. In addition, the solvent, especially ethanol, seems also to play a vital role in the stabilization of the depolymerized monomers and in the elimination/deformylation step. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Kinetic and stoichiometric characterization of organoautotrophic growth of Ralstonia eutropha on formic acid in fed-batch and continuous cultures

    PubMed Central

    Grunwald, Stephan; Mottet, Alexis; Grousseau, Estelle; Plassmeier, Jens K; Popović, Milan K; Uribelarrea, Jean-Louis; Gorret, Nathalie; Guillouet, Stéphane E; Sinskey, Anthony

    2015-01-01

    Formic acid, acting as both carbon and energy source, is a safe alternative to a carbon dioxide, hydrogen and dioxygen mix for studying the conversion of carbon through the Calvin–Benson–Bassham (CBB) cycle into value-added chemical compounds by non-photosynthetic microorganisms. In this work, organoautotrophic growth of Ralstonia eutropha on formic acid was studied using an approach combining stoichiometric modeling and controlled cultures in bioreactors. A strain deleted of its polyhydroxyalkanoate production pathway was used in order to carry out a physiological characterization. The maximal growth yield was determined at 0.16 Cmole Cmole−1 in a formate-limited continuous culture. The measured yield corresponded to 76% to 85% of the theoretical yield (later confirmed in pH-controlled fed-batch cultures). The stoichiometric study highlighted the imbalance between carbon and energy provided by formic acid and explained the low growth yields measured. Fed-batch cultures were also used to determine the maximum specific growth rate (μmax = 0.18 h−1) and to study the impact of increasing formic acid concentrations on growth yields. High formic acid sensitivity was found in R eutropha since a linear decrease in the biomass yield with increasing residual formic acid concentrations was observed between 0 and 1.5 g l−1. PMID:25123319

  14. Electrocatalytic activity of Pd-Co bimetallic mixtures for formic acid oxidation studied by scanning electrochemical microscopy.

    PubMed

    Jung, Changhoon; Sánchez-Sánchez, Carlos M; Lin, Cheng-Lan; Rodríguez-López, Joaquín; Bard, Allen J

    2009-08-15

    The electrochemical oxidation of formic acid was studied by the tip generation-substrate collection (TG-SC) mode of scanning electrochemical microscopy (SECM), extending the number of applications of SECM in electrocatalysis. Formic acid was generated at a Hg on Au ultramicroelectrode (UME) tip by reduction of CO(2) in a 0.1 M KHCO(3) solution saturated with this gas. The electrocatalytic activity of different Pd-Co bimetallic compositions was evaluated using a Pd-Co electrocatalyst array formed by spots deposited onto glassy carbon (GC) as a SECM substrate. The SECM tip, which generated a constant formic acid flux, was scanned above the array and the oxidation current generated when formic acid was collected by active electrocatalytic spots was displayed as a function of tip position. This generated a SECM image that showed the electrocatalytic activity of each spot. SECM screening identified Pd(50)Co(50) (Pd/Co = 50:50, atomic ratio) as a better electrocatalyst toward the formic acid oxidation than pure Pd or Pt in 0.1 M KHCO(3) solution and this result was confirmed by cyclic voltammetry. Positive feedback was observed for the most active compositions of Pd-Co which suggests fast reaction kinetics and chemical reversibility during the oxidation of formic acid to CO(2). Moreover this feedback increases the contrast between active and non-active spots in this imaging mode.

  15. Sources and sinks of formic, acetic, and pyruvic acids over central Amazonia. II - Wet season

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Andreae, M. O.; Berresheim, H.; Jacob, D. J.; Beecher, K. M.

    1990-01-01

    Potential sources and sinks of formic, acetic, and pyruvic acids over the Amazon forest were investigated using a photochemical model and data collected on gas phase concentrations of these acids in the forest canopy, boundary layer, and free troposphere over the central Amazon Basin during the 1987 wet season. It was found that the atmospheric reactions previously suggested in the literature as sources of carboxylic acids (i.e., the gas phase decomposition of isoprene, the reaction between CH3CO3 and a peroxide, and aqueous phase oxidation of CH2O) appear to be too slow to explain the observed concentrations, suggesting that other atmospheric reactions, so far unidentified, could make a major contribution to the carboxylic acid budgets.

  16. Formic acid, a novel metabolite of chronic ethanol abuse, causes neurotoxicity, which is prevented by folic acid.

    PubMed

    Kapur, Bhushan M; Vandenbroucke, Arthur C; Adamchik, Yana; Lehotay, Denis C; Carlen, Peter L

    2007-12-01

    Methanol is endogenously formed in the brain and is present as a congener in most alcoholic beverages. Because ethanol is preferentially metabolized over methanol (MeOH) by alcohol dehydrogenase, it is not surprising that MeOH accumulates in the alcohol-abusing population. This suggests that the alcohol-drinking population will have higher levels of MeOH's neurotoxic metabolite, formic acid (FA). FA elimination is mediated by folic acid. Neurotoxicity is a common result of chronic alcoholism. This study shows for the first time that FA, found in chronic alcoholics, is neurotoxic and this toxicity can be mitigated by folic acid administration. To determine if FA levels are higher in the alcohol-drinking population and to assess its neurotoxicity in organotypic hippocampal rat brain slice cultures. Serum and CSF FA was measured in samples from both ethanol abusing and control patients, who presented to a hospital emergency department. FA's neurotoxicity and its reversibility by folic acid were assessed using organotypic rat brain hippocampal slice cultures using clinically relevant concentrations. Serum FA levels in the alcoholics (mean +/- SE: 0.416 +/- 0.093 mmol/l, n = 23) were significantly higher than in controls (mean +/- SE: 0.154 +/- 0.009 mmol/l, n = 82) (p < 0.0002). FA was not detected in the controls' CSF (n = 20), whereas it was >0.15 mmol/l in CSF of 3 of the 4 alcoholic cases. Low doses of FA from 1 to 5 mmol/l added for 24, 48 or 72 hours to the rat brain slice cultures caused neuronal death as measured by propidium iodide staining. When folic acid (1 micromol/l) was added with the FA, neuronal death was prevented. Formic acid may be a significant factor in the neurotoxicity of ethanol abuse. This neurotoxicity can be mitigated by folic acid administration at a clinically relevant dose.

  17. Mechanistic study of electrocatalytic oxidation of formic acid at platinum in acidic solution by time-resolved surface-enhanced infrared absorption spectroscopy.

    PubMed

    Samjeské, Gabor; Miki, Atsushi; Ye, Shen; Osawa, Masatoshi

    2006-08-24

    Surface-enhanced infrared absorption spectroscopy (SEIRAS) combined with cyclic voltammetry or chronoamperometry has been utilized to examine kinetic and mechanistic aspects of the electrocatalytic oxidation of formic acid on a polycrystalline Pt surface at the molecular scale. Formate is adsorbed on the electrode in a bridge configuration in parallel to the adsorption of linear and bridge CO produced by dehydration of formic acid. A solution-exchange experiment using isotope-labeled formic acids (H(12)COOH and H(13)COOH) reveals that formic acid is oxidized to CO(2) via adsorbed formate and the decomposition (oxidation) of formate to CO(2) is the rate-determining step of the reaction. The adsorption/oxidation of CO and the oxidation/reduction of the electrode surface strongly affect the formic acid oxidation by blocking active sites for formate adsorption and also by retarding the decomposition of adsorbed formate. The interplay of the involved processes also affects the kinetics and complicates the cyclic voltammograms of formic acid oxidation. The complex voltammetric behavior is comprehensively explained at the molecular scale by taking all these effects into account.

  18. Addition of formic acid or starter cultures to liquid feed. Effect on pH, microflora composition, organic acid concentration and ammonia concentration.

    PubMed

    Canibe, N; Miquel, N; Miettinen, H; Jensen, B B

    2001-01-01

    Some of the charateristics of good quality fermented liquid feed (FLF) are low pH, high numbers of lactic acid bacteria, and low numbers of enterobacteria. In order to test strategies to avoid a proliferation of enterobacteria during the initial phase of FLF elaboration, two in vitro studies were carried out. Addition of various doses of formic acid or two different starter cultures were tested. Adding 0.1% formic acid or L. plantarum VTT E-78076 to the liquid feed seemed to be addecuate ways of inhibiting the growth of enterobacteria, without depleting the growth of lactic acid bacteria.

  19. The Partitioning of Acetic, Formic, and Phosphoric Acids Between Liquid Water and Steam

    SciTech Connect

    Gruszkiewicz, M.S.; Marshall, S.L.; Palmer, D.A.; Simonson, J.M.

    1999-06-22

    The chemical carryover of impurities and treatment chemicals from the boiler to the steam phase, and ultimately to the low-pressure turbine and condenser, can be quantified based on laboratory experiments preformed over ranges of temperature, pH, and composition. The two major assumptions are that thermodynamic equilibrium is maintained and no deposition, adsorption or decomposition occurs. The most recent results on acetic, formic and phosphoric acids are presented with consideration of the effects of hydrolysis and dimerization reactions. Complications arising from thermal decomposition of the organic acids are discussed. The partitioning constants for these acids and other solutes measured in this program have been incorporated into a simple thermodynamic computer code that calculates the effect of chemical and mechanical carryover on the composition of the condensate formed to varying extents in the water/steam cycle.

  20. CaCO3 supplementation alleviates the inhibition of formic acid on acetone/butanol/ethanol fermentation by Clostridium acetobutylicum.

    PubMed

    Qi, Gaoxiang; Xiong, Lian; Lin, Xiaoqing; Huang, Chao; Li, Hailong; Chen, Xuefang; Chen, Xinde

    2017-01-01

    To investigate the inhibiting effect of formic acid on acetone/butanol/ethanol (ABE) fermentation and explain the mechanism of the alleviation in the inhibiting effect under CaCO3 supplementation condition. From the medium containing 50 g sugars l(-1) and 0.5 g formic acid l(-1), only 0.75 g ABE l(-1) was produced when pH was adjusted by KOH and fermentation ended prematurely before the transformation from acidogenesis to solventogenesis. In contrast, 11.4 g ABE l(-1) was produced when pH was adjusted by 4 g CaCO3 l(-1). The beneficial effect can be ascribed to the buffering capacity of CaCO3. Comparative analysis results showed that the undissociated formic acid concentration and acid production coupled with ATP and NADH was affected by the pH buffering capacity of CaCO3. Four millimole undissociated formic acid was the threshold at which the transformation to solventogenesis occurred. The inhibiting effect of formic acid on ABE fermentation can be alleviated by CaCO3 supplementation due to its buffering capacity.

  1. High activity of Pd-WO3/C catalyst as anodic catalyst for direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Feng, Ligang; Yan, Liang; Cui, Zhiming; Liu, Changpeng; Xing, Wei

    2011-03-01

    Pd nanoparticles supported on the WO3/C hybrid are prepared by a two-step procedure and the catalysts are studied for the electrooxidation of formic acid. For the purpose of comparison, phosphotungstic acid (PWA) and sodium tungstate are used as the precursor of WO3. Both the Pd-WO3/C catalysts have much higher catalytic activity for the electrooxidation of formic acid than the Pd/C catalyst. The Pd-WO3/C catalyst prepared from PWA shows the best catalytic activity and stability for formic acid oxidation; it also shows the maximum power density of approximately 7.6 mW cm-2 when tested with a small single passive fuel cell. The increase of electrocatalytic activity and stability is ascribed to the interaction between the Pd and WO3, which promotes the oxidation of formic acid in the direct pathway. The precursors used for the preparation of the WO3/C hybrid support have a great effect on the performance of the Pd-WO3/C catalyst. The WO3/C hybrid support prepared from PWA is beneficial to the dispersion of Pd nanoparticles, and the catalyst has potential application for direct formic acid fuel cell.

  2. Effects of Nafion loading in anode catalyst inks on the miniature direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Morgan, Robert D.; Haan, John L.; Masel, Richard I.

    Nafion, within the anode and cathode catalyst layers, plays a large role in the performance of fuel cells, especially during the operation of the direct formic acid fuel cell (DFAFC). Nafion affects the proton transfer in the catalyst layers of the fuel cell, and studies presented here show the effects of three different Nafion loadings, 10 wt.%, 30 wt.% and 50 wt.%. Short term voltage-current measurements using the three different loadings show that 30 wt.% Nafion loading in the anode shows the best performance in the miniature, passive DFAFC. Nafion also serves as a binder to help hold the catalyst nanoparticles onto the proton exchange membrane (PEM). The DFAFC anode temporarily needs to be regenerated by raising the anode potential to around 0.8 V vs. RHE to oxidize CO bound to the surface, but the Pourbaix diagram predicts that Pd will corrode at these potentials. We found that an anode loading of 30 wt.% Nafion showed the best stability, of the three Nafion loadings chosen, for reducing the amount of loss of electrochemically active area due to high regeneration potentials. Only 58% of the area was lost after 600 potential cycles in formic acid compared to 96 and 99% for 10 wt.% and 50 wt.% loadings, respectively. Lastly we present cyclic voltammetry data that suggest that the Nafion adds to the production of CO during oxidation of formic acid for 12 h at 0.3 V vs. RHE. The resulting data showed that an increase in CO coverage was observed with increasing Nafion content in the anode catalyst layer.

  3. Size effects in electronic and catalytic properties of unsupported palladium nanoparticles in electrooxidation of formic acid.

    PubMed

    Zhou, Wei Ping; Lewera, Adam; Larsen, Robert; Masel, Rich I; Bagus, Paul S; Wieckowski, Andrzej

    2006-07-13

    We report a combined X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and chronoamperometry (CA) study of formic acid electrooxidation on unsupported palladium nanoparticle catalysts in the particle size range from 9 to 40 nm. The CV and CA measurements show that the most active catalyst is made of the smallest (9 and 11 nm) Pd nanoparticles. Besides the high reactivity, XPS data show that such nanoparticles display the highest core-level binding energy (BE) shift and the highest valence band (VB) center downshift with respect to the Fermi level. We believe therefore that we found a correlation between formic acid oxidation current and BE and VB center shifts, which, in turn, can directly be related to the electronic structure of palladium nanoparticles of different particle sizes. Clearly, such a trend using unsupported catalysts has never been reported. According to the density functional theory of heterogeneous catalysis, and mechanistic considerations, the observed shifts are caused by a weakening of the bond strength of the COOH intermediate adsorption on the catalyst surface. This, in turn, results in the increase in the formic acid oxidation rate to CO2 (and in the associated oxidation current). Overall, our measurements demonstrate the particle size effect on the electronic properties of palladium that yields different catalytic activity in the HCOOH oxidation reaction. Our work highlights the significance of the core-level binding energy and center of the d-band shifts in electrocatalysis and underlines the value of the theory that connects the center of the d-band shifts to catalytic reactivity.

  4. Mechanism of Pt(IV) sonochemical reduction in formic acid media and pure water.

    PubMed

    Chave, Tony; Navarro, Nathalie M; Nitsche, Serge; Nikitenko, Sergey I

    2012-03-26

    Sonochemical synthesis of platinum nanoparticles (Pt NPs) in formic acid solutions and pure water was investigated using a 20 kHz ultrasonic irradiation. The obtained results gave new insights on the underneath Pt(IV)  reduction mechanism in formic acid media under argon and in pure water under Ar/CO atmosphere. It was shown that in pure water sonochemical reduction of platinum ions occurs by hydrogen issued from homolytic water molecule split. Pt(IV) ion reduction appears to be a very slow process under argon atmosphere in pure water due to formation of oxidizing species like OH radicals and H(2)O(2) leading to reoxidation of intermediate Pt(II)  ions. Sonochemical reduction is accelerated manifold in the presence of formic acid or Ar/CO gas mixture. Solution and gas-phase analyses reveal that both CO and HCOOH act as OH(.) radical scavenger and reducing agent under ultrasonic irradiation. Their ability to reduce platinum ions at room temperature is enhanced due to the local heating in the liquid shell surround the cavitation bubble. An innovative synthesis route for monodispersed Pt NPs in pure water without any templates or capping agents in the presence of Ar/CO gas mixture is then proposed. Obtained Pt NPs within the range of 2-3 nm exhibited a strong stability towards sedimentation in water. Since Ar/CO atmosphere is the only restriction of the process, this procedure can be applied in various media and is also compatible with a large array of experimental conditions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Solar to Liquid Fuels Production: Light-Driven Reduction of Carbon Dioxide to Formic Acid

    DTIC Science & Technology

    2014-03-29

    AFRL-OSR-VA-TR-2014-0088 SOLAR TO LIQUID FUELS PRODUCTION : LIGHT-DRIVEN REDUCTION OF CARBON DIOXIDE TO FO John Golbeck PENNSYLVANIA STATE UNIVERSITY...Standard Form 298 (Re . 8-98) v Prescribed by ANSI Std. Z39.18 1 Project FA9550-09-1-0671: Solar to Liquid Fuels Production : Light-Driven Reduction of...potential is decreased, the rate of formic acid production increases linearly up to a maximum of –0.8 V. CO2 reduction is greatest at pH 5.5, but it

  6. Iodide-Photocatalyzed Reduction of Carbon Dioxide to Formic Acid with Thiols and Hydrogen Sulfide.

    PubMed

    Berton, Mateo; Mello, Rossella; González-Núñez, María Elena

    2016-12-20

    The photolysis of iodide anions promotes the reaction of carbon dioxide with hydrogen sulfide or thiols to quantitatively yield formic acid and sulfur or disulfides. The reaction proceeds in acetonitrile and aqueous solutions, at atmospheric pressure and room temperature by irradiation using a low-pressure mercury lamp. This transition-metal-free photocatalytic process for CO2 capture coupled with H2 S removal may have been relevant as a prebiotic carbon dioxide fixation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Direct synthesis of graphene nanosheets support Pd nanodendrites for electrocatalytic formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Yang, Su-Dong; Chen, Lin

    2015-11-01

    We report a solvothermal method preparation of dendritic Pd nanoparticles (DPNs) and spherical Pd nanoparticles (SPNs) supported on reduced graphene oxide (RGO). Drastically different morphologies of Pd NPs with nanodendritic structures or spherical structures were observed on graphene by controlling the reduction degree of graphene oxide (GO) under mild conditions. In addition to being a commonplace substrate, GO plays a more important role that relies on its surface groups, which serves as a shape-directing agent to direct the dendritic growth. As a result, the obtained DPNs/RGO catalyst exhibits a significantly enhanced electro-catalytic behavior for the oxidation of formic acid compared to the SPNs/RGO catalyst.

  8. SnO2 nanospheres supported Pd catalyst with enhanced performance for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Lu, Haiting; Fan, Yang; Huang, Ping; Xu, Dongli

    2012-10-01

    SnO2 nanospheres were employed as the support material for Pd catalyst. The as-prepared Pd/SnO2 catalyst exhibited remarkably improved electrocatalytic activity and stability towards formic acid oxidation, in comparison with that of the Vulcan XC-72 carbon black and the commercial SnO2 nanopowder supported Pd catalyst. The enhanced catalytic performance may arise from the unique structure and surface properties of the SnO2 nanospheres, which process extraordinary promotional effect on Pd catalyst.

  9. Highly dispersed Pd nanoparticles on chemically modified graphene with aminophenyl groups for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Yang, Su-Dong; Shen, Cheng-Min; Tong, Hao; He, Wei; Zhang, Xiao-Gang; Gao, Hong-Jun

    2011-11-01

    A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine. Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction. The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts.

  10. Corrosion behavior and inhibitive effects on organotin compounds on nickel in formic acid

    SciTech Connect

    Singh, R.N.; Singh, V.B. . Dept. of Chemistry)

    1993-07-01

    Corrosion behavior of nickel (Ni) in different compositions of formic acid (HCOOH) at 30C was studied using the potentiostatic polarization method. The shape of the polarization curve was evaluated, and the corrosion current density, critical current density, and passive current density were determined. HCOOH solution of different composition were aggressive for the anodic dissolution of Ni, except for 20 and 30 mol/O HCOOH, in which feeble passitivity was observed. The organometallic compounds dibutyltin dichloride, phenyltin trichloride, diphenyltin dichloride, and triphenyltin chloride ([C[sub 6]H[sub 5

  11. Interconversion of CO2 and formic acid by bio-inspired Ir complexes with pendent bases.

    PubMed

    Fujita, Etsuko; Muckerman, James T; Himeda, Yuichiro

    2013-01-01

    Recent investigations of the interconversion of CO2 and formic acid using Ru, Ir and Fe complexes are summarized in this review. During the past several years, both the reaction rates and catalyst stabilities have been significantly improved. Remarkably, the interconversion (i.e., reversibility) has also been achieved under mild conditions in environmentally benign water solvent by slightly changing the pH of the aqueous solution. Only a few catalysts seem to reflect a bio-inspired design such as the use of proton responsive ligands, ligands with pendent bases or acids for a second-coordination-sphere interaction, electroresponsive ligands, and/or ligands having a hydrogen bonding function with a solvent molecule or an added reagent. The most successful of these is an iridium dinuclear complex catalyst that at least has the first three of these characteristics associated with its bridging ligand. By utilizing an acid/base equilibrium for proton removal, the ligand becomes a strong electron donor, resulting in Ir(I) character with a vacant coordination site at each metal center in slightly basic solution. Complemented by DFT calculations, kinetic studies of the rates of formate production using a related family of Ir complexes with and without such functions on the ligand reveal that the rate-determining step for the CO2 hydrogenation is likely to be H2 addition through heterolytic cleavage involving a "proton relay" through the pendent base. The dehydrogenation of formic acid, owing to the proton responsive ligands changing character under slightly acidic pH conditions, is likely to occur by a mechanism with a different rate-determining step. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    NASA Astrophysics Data System (ADS)

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-09-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h‑1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance.

  13. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    PubMed Central

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-01-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h−1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance. PMID:27666280

  14. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition.

    PubMed

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-09-26

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h(-1)) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance.

  15. Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

    NASA Astrophysics Data System (ADS)

    Karicheva, E.; Guseva, N.; Kambalina, M.

    2016-03-01

    Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula. The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

  16. Technical and economical assessment of formic acid to recycle phosphorus from pig slurry by a combined acidification-precipitation process.

    PubMed

    Daumer, M-L; Picard, S; Saint-Cast, P; Dabert, P

    2010-08-15

    Dissolution by acidification followed by a liquid/solid separation and precipitation of phosphorus from the liquid phase is one possibility to recycle phosphorus from livestock effluents. To avoid increase of effluent salinity by using mineral acids in the recycling process, the efficiency of two organic acids, formic and acetic acid, in dissolving the mineral phosphorus from piggery wastewater was compared. The amount of formic acid needed to dissolve the phosphorus was reduced three fold, compared to acetic acid. The amount of magnesium oxide needed for further precipitation was decreased by two with formic acid. Neither the carbon load nor the effluent salinity was significantly increased by using formic acid. An economical comparison was performed for the chemical recycling process (mineral fertilizer) vs. centrifugation (organic fertilizer) considering the centrifugation and the mineral fertilizers sold in the market. After optimisation of the process, the product could be economically competitive with mineral fertilizer as superphosphate in less than 10 years. Copyright 2010 Elsevier B.V. All rights reserved.

  17. Formic and Acetic Acid Observations over Colorado by Chemical Ionization Mass Spectrometry and Organic Acids' Role in Air Quality

    NASA Astrophysics Data System (ADS)

    Treadaway, V.; O'Sullivan, D. W.; Heikes, B.; Silwal, I.; McNeill, A.

    2015-12-01

    Formic acid (HFo) and acetic acid (HAc) have both natural and anthropogenic sources and a role in the atmospheric processing of carbon. These organic acids also have an increasing importance in setting the acidity of rain and snow as precipitation nitrate and sulfate concentrations have decreased. Primary emissions for both organic acids include biomass burning, agriculture, and motor vehicle emissions. Secondary production is also a substantial source for both acids especially from biogenic precursors, secondary organic aerosols (SOAs), and photochemical production from volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs). Chemical transport models underestimate organic acid concentrations and recent research has sought to develop additional production mechanisms. Here we report HFo and HAc measurements during two campaigns over Colorado using the peroxide chemical ionization mass spectrometer (PCIMS). Iodide clusters of both HFo and HAc were recorded at mass-to-charge ratios of 173 and 187, respectively. The PCIMS was flown aboard the NCAR Gulfstream-V platform during the Deep Convective Clouds and Chemistry Experiment (DC3) and aboard the NCAR C-130 during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE). The DC3 observations were made in May and June 2012 extending from the surface to 13 km over the central and eastern United States. FRAPPE observations were made in July and August 2014 from the surface to 7 km over Colorado. DC3 measurements reported here are focused over the Colorado Front Range and complement the FRAPPE observations. DC3 HFo altitude profiles are characterized by a decrease up to 6 km followed by an increase either back to boundary layer mixing ratio values or higher (a "C" shape). Organic acid measurements from both campaigns are interpreted with an emphasis on emission sources (both natural and anthropogenic) over Colorado and in situ photochemical production especially ozone precursors.

  18. Hydrogen bonding in the hydroxysulfinyl radical-formic acid-water system: A theoretical study.

    PubMed

    Tušar, Simona; Lesar, Antonija

    2016-06-30

    Quantum chemical methods have been employed to evaluate the possible configurations of the 1:1 and 1:2 HOSO-formic acid complexes and 1:1:1 HOSO-formic acid-water complexes. The first type of complex involves two H bonds, while the other two types comprise three H bonds in a ring. The complexes are relatively stable, with CBS-QB3 computed binding energies of 14.3 kcal mol(-1) , 23.4 kcal mol(-1) , and 21.1 kcal mol(-1) for the lowest-energy structures of the 1:1, 1:2, and 1:1:1 complexes, respectively. Complex formations induce a large spectral red-shift and an enhancement of the IR intensity for the H-bonded OH stretching modes relative to those in the parent monomers. TDDFT calculations of the low-lying electronic excited states demonstrate that the complexes are photochemically quite stable in the troposphere. Small spectral shifts in comparison to the free HOSO radical suggest that the radical and the complexes would not be easily distinguishable using standard UV/vis absorption spectroscopy. © 2016 Wiley Periodicals, Inc.

  19. Hydrogenation of CO2 to formic acid over a Cu-embedded graphene: A DFT study

    NASA Astrophysics Data System (ADS)

    Sirijaraensre, J.; Limtrakul, J.

    2016-02-01

    DFT calculations were used to investigate the properties of the atomic copper embedded in the surface of graphene (Cu/dG) and the catalytic reaction pathway for the CO2 hydrogenation to formic acid (FA). The Cu/dG was active for the adsorption of the hydrogen molecule (H2), and provided a reaction site for the heterolytic cleavage of H2, leading to the formation of Cu-H deposited on a singly hydrogenated vacancy graphene (Cu-H/H-dG). The protonation of CO2 takes place facilely over the generated metal-hydride species (Cu-H). Under the dilution of H2, the catalytic process would be hampered by the formation of copper-formate deposited on the H-dG due mainly to the very high energy demand for the transformation of the copper-formate to FA through the protonation from the H-dG. It was further found that the presence of H2 in the system plays a significant role in producing the FA on the Cu/dG catalyst. The copper-formate species can be converted into formic acid via the heterolytic cleavage of the second hydrogen molecule, yielding the FA and Cu-H species.

  20. Supportless, bismuth-modified palladium nanotubes with improved activity and stability for formic acid oxidation

    SciTech Connect

    Atkinson, III, Robert W.; St. John, Samuel; Dyck, Ondrej; Unocic, Kinga A.; Unocic, Raymond R.; Burke, Colten S.; Cisco, Joshua W.; Rice, Cynthia A.; Zawodzinski, Jr., Thomas A.; Papandrew, Alexander B.

    2015-07-22

    Palladium nanotubes (PdNTs) were synthesized by templated vapor deposition and investigated for formic acid electrooxidation. Annealed PdNTs are 2.4 times more active (2.19 mA/cm2) than commercial carbon-supported palladium (0.91 mA/cm2) at 0.3 V vs RHE. Bismuth modification improved nanotube performance over 4 times (3.75 mA/cm2) vs Pd/C and nearly 2 times vs unmodified PdNTs. A surface Bi coverage of 80% results in optimal site-specific activity by drastically reducing surface-poisoning CO generation during formic acid electrooxidation. The Bi-modified PdNTs are exceptionally stable, maintaining 2 times the area-normalized current density as Pd/C after 24 h at 0.2 V vs RHE. As a result, we attribute the enhanced activity and stability of the nanotube catalysts to the presence of highly coordinated surfaces, mimicking a flat polycrystal while retaining high surface area geometry.

  1. Chemical reactions induced in frozen formic acid by heavy ion cosmic rays

    NASA Astrophysics Data System (ADS)

    Andrade, Diana P. P.; de Barros, Ana L. F.; Pilling, Sérgio; Domaracka, Alicja; Rothard, Hermann; Boduch, Philippe; da Silveira, Enio F.

    2013-04-01

    We studied the effects produced by the interaction of heavy ion cosmic rays with interstellar and cometary organic molecules in the solid phase. Formic acid (HCOOH) ice at 15 K was irradiated by 267-MeV 56Fe22+ ions and the chemical evolution was analysed using Fourier transform infrared spectroscopy. The destruction cross-section of HCOOH and the formation cross-sections of the produced molecular species have been determined; the sputtering yield values are also discussed. The most abundant chemical species formed by Fe ion irradiation are CO, CO2 and H2O. The half-life of frozen formic acid molecules in the interstellar medium, as a result of interaction with the different cosmic ray constituents, is evaluated to be 108 yr, considering that the destruction cross-section σd of heavy ions is ruled by a power law as a function of the electronic stopping power Se (i.e. σd ˜ S3/2e). Moreover, a complementary study based on mass spectrometry data from the literature has been performed, in order to understand the HCOOH molecule radiolysis, the desorption of its product and the chemical reaction pathways in ice.

  2. Hollow palladium nanospheres with porous shells supported on graphene as enhanced electrocatalysts for formic acid oxidation.

    PubMed

    Wang, Bo; Yang, Jun; Wang, Lei; Wang, Ruihong; Tian, Chungui; Jiang, Baojiang; Tian, Mei; Fu, Honggang

    2013-11-28

    The hollow palladium nanospheres with the porous shell comprised of uniform 5 nm Pd nanoparticles (Pd NS-HP) have been synthesized successfully by employing a simple replacement process between PdCl4(2-) ions and Co with the assistance of a structure-directing agent, polyvinyl pyrrolidone (PVP). Then, the obtained Pd NS-HP is supported on graphene nanosheets (GN) to prepare Pd NS-HP/GN composites by a wet-impregnation method. As the catalyst towards formic acid electrooxidation, the Pd NS-HP/GN composite exhibits a larger electrochemically active surface area, better electrocatalytic activity and better stability compared with Pd nanoparticles/graphene (Pd NP/GN) and commercial Pd/C catalysts. The enhancement in electrocatalytic performance of Pd NS-HP/GN is attributed to the abundant connected pore channels in the inner and exterior surfaces of Pd nanospheres, which could provide a large contact surface for adsorption and transmission of reactants, facilitating the oxidation of formic acid molecules on its surface and also improving the utilization of Pd metal. Moreover, the support of graphene could enhance the stability of the catalyst.

  3. Highly active and durable platinum-lead bimetallic alloy nanoflowers for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Gong, Mingxing; Li, Fumin; Yao, Zhigang; Zhang, Suqi; Dong, Jingwen; Chen, Yu; Tang, Yawen

    2015-03-01

    The Pt84Pb16 (atomic ratio) bimetallic alloy nanoflowers (Pt84Pb16 BANFs) are synthesized by a simple one-pot hydrothermal reduction method that effectively enhance the dehydrogenation pathway of the formic acid oxidation reaction (FAOR) due to the ensemble effect and the electronic effect. As a result, the mass activity of Pt84Pb16 BANFs for the FAOR is 16.7 times higher than that of commercial Pt black at 0.3 V potential.The Pt84Pb16 (atomic ratio) bimetallic alloy nanoflowers (Pt84Pb16 BANFs) are synthesized by a simple one-pot hydrothermal reduction method that effectively enhance the dehydrogenation pathway of the formic acid oxidation reaction (FAOR) due to the ensemble effect and the electronic effect. As a result, the mass activity of Pt84Pb16 BANFs for the FAOR is 16.7 times higher than that of commercial Pt black at 0.3 V potential. Electronic supplementary information (ESI) available: Experimental details. See DOI: 10.1039/c4nr07375d

  4. Computational Study of Formic Acid Dehydrogenation Catalyzed by Al(III)-Bis(imino)pyridine.

    PubMed

    Lu, Qian-Qian; Yu, Hai-Zhu; Fu, Yao

    2016-03-18

    The mechanism of formic acid dehydrogenation catalyzed by the bis(imino)pyridine-ligated aluminum hydride complex (PDI(2-))Al(THF)H (PDI=bis(imino)pyridine) was studied by density functional theory calculations. The overall transformation is composed of two stages: catalyst activation and the catalytic cycle. The catalyst activation begins with O-H bond cleavage of HCOOH promoted by aluminum-ligand cooperation, followed by HCOOH-assisted Al-H bond cleavage, and protonation of the imine carbon atom of the bis(imino)pyridine ligand. The resultant doubly protonated complex ((H,H) PDI)Al(OOCH)3 is the active catalyst for formic acid dehydrogenation. Given this, the catalytic cycle includes β-hydride elimination of ((H,H) PDI)Al(OOCH)3 to produce CO2, and the formed ((H,H) PDI)Al(OOCH)2 H mediates HCOOH to release H2. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Nanocrystalline intermetallics on mesoporous carbon for direct formic acid fuel cell anodes.

    PubMed

    Ji, Xiulei; Lee, Kyu Tae; Holden, Reanne; Zhang, Lei; Zhang, Jiujun; Botton, Gianluigi A; Couillard, Martin; Nazar, Linda F

    2010-04-01

    Shape- and size-controlled supported metal and intermetallic nanocrystallites are of increasing interest because of their catalytic and electrocatalytic properties. In particular, intermetallics PtX (X = Bi, Pb, Pd, Ru) are very attractive because of their high activity as fuel-cell anode catalysts for formic acid or methanol oxidation. These are normally synthesized using high-temperature techniques, but rigorous size control is very challenging. Even low-temperature techniques typically produce nanoparticles with dimensions much greater than the optimum <6 nm required for fuel cell catalysis. Here, we present a simple and robust, chemically controlled process for synthesizing size-controlled noble metal or bimetallic nanocrystallites embedded within the porous structure of ordered mesoporous carbon (OMC). By using surface-modified ordered mesoporous carbon to trap the metal precursors, nanocrystallites are formed with monodisperse sizes as low as 1.5 nm, which can be tuned up to ∼3.5 nm. To the best of our knowledge, 3-nm ordered mesoporous carbon-supported PtBi nanoparticles exhibit the highest mass activity for formic acid oxidation reported to date, and over double that of Pt-Au.

  6. Nanocrystalline intermetallics on mesoporous carbon for direct formic acid fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Ji, Xiulei; Lee, Kyu Tae; Holden, Reanne; Zhang, Lei; Zhang, Jiujun; Botton, Gianluigi A.; Couillard, Martin; Nazar, Linda F.

    2010-04-01

    Shape- and size-controlled supported metal and intermetallic nanocrystallites are of increasing interest because of their catalytic and electrocatalytic properties. In particular, intermetallics PtX (X = Bi, Pb, Pd, Ru) are very attractive because of their high activity as fuel-cell anode catalysts for formic acid or methanol oxidation. These are normally synthesized using high-temperature techniques, but rigorous size control is very challenging. Even low-temperature techniques typically produce nanoparticles with dimensions much greater than the optimum <6 nm required for fuel cell catalysis. Here, we present a simple and robust, chemically controlled process for synthesizing size-controlled noble metal or bimetallic nanocrystallites embedded within the porous structure of ordered mesoporous carbon (OMC). By using surface-modified ordered mesoporous carbon to trap the metal precursors, nanocrystallites are formed with monodisperse sizes as low as 1.5 nm, which can be tuned up to ~3.5 nm. To the best of our knowledge, 3-nm ordered mesoporous carbon-supported PtBi nanoparticles exhibit the highest mass activity for formic acid oxidation reported to date, and over double that of Pt-Au.

  7. Electrodeposition of Pd catalyst layer on graphite rod electrodes for direct formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Ye, Dingding; Li, Jun; Zhu, Xun; Liao, Qiang

    2012-09-01

    An electrodeposition method for preparing the Pd catalyst layer on graphite rod electrodes for direct formic acid oxidation is proposed in this study. This method consists of a repeated procedure involving the electrodeposition of Pd catalyst onto the graphite rods, followed by Nafion coating (RENC). The structural features and electrocatalytic properties of the electrode were extensively investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results show that coating the electrode with Nafion during each electrodepositing step plays a crucial role on the morphology, particle size and crystallinity of the electrocatalysts. Although the commercial Pd catalyst has the smaller particle size and more uniform distribution than that prepared by RENC, the RENC electrode exhibits almost the same electrochemical surface area, a better performance and durability toward formic acid electro-oxidation. These results can be attributed to the improved catalyst utilization resulting from the multi-layer structure and the predominance of the highly active Pd (111) crystallite phase on the surface of the catalyst layer.

  8. Formic acid microfluidic fuel cell based on well-defined Pd nanocubes

    NASA Astrophysics Data System (ADS)

    Moreno-Zuria, A.; Dector, A.; Arjona, N.; Guerra-Balcázar, M.; Ledesma-García, J.; Esquivel, J. P.; Sabaté, N.; Arrriaga, L. G.; Chávez-Ramírez, A. U.

    2013-12-01

    Microfluidic fuel cells (μFFC) are emerging as a promising solution for small-scale power demands. The T-shaped architecture of the μFFC promotes a laminar flow regimen between the catholyte and anolyte streams excluding the use of a membrane, this property allows a simplest design and the use of several micromachining techniques based on a lab-on-chip technologies. This work presents a combination of new materials and low cost fabrication processes to develop a light, small, flexible and environmental friendly device able to supply the energy demand of some portable devices. Well-defined and homogeneous Pd nanocubes which exhibited the (100) preferential crystallographic plane were supported on Vulcan carbon and used as anodic electrocatalyst in a novel and compact design of a SU-8 μFFC feeded with formic acid as fuel. The SU-8 photoresist properties and the organic microelectronic technology were important factors to reduce the dimensions of the μFFC structure. The results obtained from polarization and power density curves exhibited the highest power density (8.3 mW cm-2) reported in literature for direct formic acid μFFCs.

  9. Efficient production of hydrogen from formic acid using a covalent triazine framework supported molecular catalyst.

    PubMed

    Bavykina, A V; Goesten, M G; Kapteijn, F; Makkee, M; Gascon, J

    2015-03-01

    A heterogeneous molecular catalyst based on Ir(III) Cp* (Cp*=pentamethylcyclopentadienyl) attached to a covalent triazine framework (CTF) is reported. It catalyses the production of hydrogen from formic acid with initial turnover frequencies (TOFs) up to 27,000 h(-1) and turnover numbers (TONs) of more than one million in continuous operation. The CTF support, with a Brunauer-Emmett-Teller (BET) surface area of 1800 m(2)  g(-1), was constructed from an optimal 2:1 ratio of biphenyl and pyridine carbonitrile building blocks. Biphenyl building blocks induce mesoporosity and, therefore, facilitate diffusion of reactants and products whereas free pyridinic sites activate formic acid towards β-hydride elimination at the metal, rendering unprecedented rates in hydrogen production. The catalyst is air stable, produces CO-free hydrogen, and is fully recyclable. Hydrogen production rates of more than 60 mol L(-1)  h(-1) were obtained at high catalyst loadings of 16 wt % Ir, making it attractive towards process intensification. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Hydrothermal conversion of CO2 into formic acid on the catalysis of Cu

    NASA Astrophysics Data System (ADS)

    Zhong, Heng; Jin, Fangming; Wu, Bing; Chen, Hongjuan; Yao, Guodong

    2010-11-01

    Nowadays, a series of ecological problems caused by the greenhouse effect have had huge impacts on human beings' health, existence, manufacturing, environment and biological species. To avoid that, the emission of CO2, the major greenhouse gas, should be reduced as soon as possible. Researchers have done a lot of work and suggested dozens of methods to deal with CO2. However, these methods do not fundamentally solve the problem of CO2. Recently, hydrothermal process is considered to be one of the most promising processes for the reduction of CO2, because the water of high temperature and pressure has remarkable properties as a reaction medium. In this research, the effect of Cu catalyst on the conversion of CO2 into formic acid was investigated using Fe as reductant in water solvent. A series of experiments were conducted at different experimental parameters, e.g. amount of Fe (Cu), temperature, reaction time etc. Results showed that the highest yield of 46% for formic acid can be obtained under the following condition, Fe/Cu ratio of 1:1, CO2/Fe ratio of 1:6, filling rate of 35%, temperature of 300° C, reaction time of 120 min.

  11. Formic acid electrooxidation on Bi-modified polyoriented and preferential (111) Pt nanoparticles.

    PubMed

    López-Cudero, Ana; Vidal-Iglesias, Francisco J; Solla-Gullón, José; Herrero, Enrique; Aldaz, Antonio; Feliu, Juan M

    2009-01-14

    Formic acid electrooxidation was studied on Bi modified polyoriented and preferential (111) Pt nanoparticles. For both types of nanoparticles, Bi coverage was progressively increased and its effect on formic acid electrooxidation was evaluated using cyclic voltammetry and chronoamperometric measurements. In both experiments, significant and progressive enhancements on the electrooxidation current densities were obtained in comparison to the bare Pt nanoparticles. In voltammetry, at maximum Bi coverage, higher current densities at peak potential were obtained with the preferential (111) Pt nanoparticles (approximately 42 mA cm(-2)) as compared to the polyoriented Pt nanoparticles (approximately 32 mA cm(-2)) in agreement with previous single crystal studies. Nevertheless, this tendency was not observed in chronoamperometry at 0.4 V where currents obtained at maximum Bi coverage were similar. On the other hand, CO poison formation was also evaluated at open circuit potential. The resulting electrochemical activity has been rationalized using different parameters, such as surface structure, size domains, particle size and Bi coverage.

  12. Novel silk fibroin films prepared by formic acid/hydroxyapatite dissolution method.

    PubMed

    Ming, Jinfa; Liu, Zhi; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

    2014-04-01

    Bombyx mori silk fibroin from the silkworm was firstly found to be soluble in formic acid/hydroxyapatite system. The rheological behavior of silk fibroin solution was significantly influenced by HAp contents in dissolved solution. At the same time, silk fibroin nanofibers were observed in dissolved solution with 103.6±20.4nm in diameter. Moreover, the structure behavior of SF films prepared by formic acid/hydroxyapatite dissolution method was examined. The secondary structure of silk fibroin films was attributed to silk II structure (β-sheet), indicating that the hydroxyapatite contents in dissolved solution were not significantly affected by the structure of silk fibroin. The X-ray diffraction results exhibited obviously hydroxyapatite crystalline nature existing in silk fibroin films; however, when the hydroxyapatite content was 5.0wt.% in dissolved solution, some hydroxyapatite crystals were converted to calcium hydrogen phosphate dehydrate in silk fibroin dissolution process. This result was also confirmed by Fourier transform infrared analysis and DSC measurement. In addition, silk fibroin films prepared by this dissolution method had higher breaking strength and extension at break. Based on these analyses, an understanding of novel SF dissolution method may provide an additional tool for designing and synthesizing advanced materials with more complex structures, which should be helpful in different fields, including biomaterial applications.

  13. Multibubble sonoluminescence as a tool to study the mechanism of formic acid sonolysis.

    PubMed

    Navarro, Nathalie M; Pflieger, Rachel; Nikitenko, Sergey I

    2014-05-01

    Sonoluminescence spectra collected from 0.1 to 3.0M aqueous solutions of formic acid sparged with argon show the OH(A(2)Σ(+)-X(2)Πi) and C2(d(3)Πg → a(3)Πu) emission bands and a broad continuum typical for multibubble sonoluminescence. The overall intensity of sonoluminescence and the sonochemical yield of HCOOH degradation vary in opposite directions: the sonoluminescence is quenched while the sonochemical yield increases with HCOOH concentration. By contrast, the concentration of formic acid has a relatively small effect on the intensity of C2 Swan band. It is concluded that C2 emission originates from CO produced by HCOOH degradation rather than from direct sonochemical degradation of HCOOH. The intensity of C2 band is much stronger at high ultrasonic frequency compared to 20 kHz ultrasound which is in line with higher yields of CO at high frequency. Another product of HCOOH sonolysis, carbon dioxide, strongly quenches sonoluminescence, most probably via collisional non-radiative mechanism. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. An intercomparison of measurement systems for vapor and particulate phase concentrations of formic and acetic acids

    NASA Technical Reports Server (NTRS)

    Keene, William C.; Talbot, Robert W.; Andreae, Meinrat O.; Beecher, Kristene; Berresheim, Harold

    1989-01-01

    During June 1986, eight systems for measuring vapor phase and four for measuring particulate phase concentrations of formic acid (HCOOH) and acetic acid (CH3COOH) were intercompared in central Virginia. HCOOH and CH3COOH vapors were sampled by condensate, mist, Chromosorb 103 GC resin, NaOH-coated annular denuders, NaOH-impregnated quartz filters, K2CO3 and NaCO3-impregnated cellulose filters, and Nylasorb membranes. Atmospheric aerosol was collected on Teflon and Nuclepore filters using both hi-vol and lo-vol systems to measure particulate phase concentrations. Performances of the mist chamber and K2CO3-impregnated filter techniques were evaluated using zero air and ambient air spiked with HCOOH(g) and CH3COOH(g), and formaldehyde from permeation sources. The advantages and drawbacks of these methods are reported and discussed.

  15. Catalytic Hydrotreatment of Humins in Mixtures of Formic Acid/2-Propanol with Supported Ruthenium Catalysts.

    PubMed

    Wang, Yuehu; Agarwal, Shilpa; Kloekhorst, Arjan; Heeres, Hero Jan

    2016-05-10

    The catalytic hydrotreatment of humins, which are the solid byproducts from the conversion of C6 sugars (glucose, fructose) into 5-hydroxymethylfurfural (HMF) and levulinic acid (LA), by using supported ruthenium catalysts has been investigated. Reactions were carried out in a batch setup at elevated temperatures (400 °C) by using a hydrogen donor (formic acid (FA) in isopropanol (IPA) or hydrogen gas), with humins obtained from d-glucose. Humin conversions of up to 69 % were achieved with Ru/C and FA, whereas the performance for Ru on alumina was slightly poorer (59 % humin conversion). Humin oils were characterized by using a range of analytical techniques (GC, GC-MS, GCxGC, gel permeation chromatography) and were shown to consist of monomers, mainly alkyl phenolics (>45 % based on compounds detectable by GC) and higher oligomers. A reaction network for the reaction is proposed based on structural proposals for humins and the main reaction products.

  16. Sulfonation of ordered mesoporous carbon supported Pd catalysts for formic acid electrooxidation.

    PubMed

    Sun, Zhi-Peng; Zhang, Xiao-Gang; Tong, Hao; Liang, Yan-Yu; Li, Hu-Lin

    2009-09-15

    A novel supporting material containing benzenesulfonic acid (BSA) groups and ordered mesoporous carbons (OMCs) was first prepared by in situ radical polymerization of 4-styrenesulfonate and isoamyl nitrite under ambient conditions. Then, Pd nanoparticles were deposited on as-produced OMCs (f-OMCs) by the NaBH(4) reduction method. The structure and nature of the resulting composites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nitrogen adsorption-desorption. The results show that BSA groups are created and the texture and surface chemistry are altered, whereas the ordered porous structure is maintained. The electrocatalytic properties of the Pd/f-OMCs catalysts for formic acid oxidation (HCOOH) have been investigated by cyclic voltammetry and chronoamperometry methods, and excellent electrocatalytic activity can be observed.

  17. Particle size control of Pd/C for improved electrocatalytic activity in a formic acid oxidation.

    PubMed

    Woo, Seunghee; Kim, In; Bong, Sungyool; Lee, Jaeyoung; Kim, Hasuck

    2011-08-01

    Carbon-supported Pd electrocatalyst is prepared by an improved aqueous impregnation method applying a reducing agent of HCHO and an acidic sedimentation promoter of HCl. We investigate the effect of a solution pH on the zeta potential of both Pd particles and carbon support. The opposite sign of zeta potential results in uniform dispersion of Pd on carbon surface without aggregation problem. TEM analysis shows that optimal solution pH of 4.27 adjusted by NaOH provides a mean particle diameter of 3.2 nm with narrow size distribution. Cyclic voltammograms indicate that home-made Pd/C catalyst exhibits significantly higher electrochemical active surface area and better stability compared with commercial 40 wt.% Pd/C in a formic acid oxidation.

  18. Photoinduced reduction of divalent mercury by quinones in the presence of formic acid under anaerobic conditions.

    PubMed

    Berkovic, Andrea M; Bertolotti, Sonia G; Villata, Laura S; Gonzalez, Mónica C; Pis Diez, Reinaldo; Mártire, Daniel O

    2012-11-01

    The laser flash photolysis technique (λ(exc)=355 nm) was used to investigate the mechanism of the HgCl(2) reduction mediated by CO(2)(-) radicals generated from quenching of the triplet states of 1,4-naphthoquinone (NQ) by formic acid. Kinetic simulations of the experimental signals support the proposed reaction mechanism. This system is of potential interest in the development of UV-A photoinduced photolytic procedures for the treatment of Hg(II) contaminated waters. The successful replacement of NQ with a commercial fulvic acid, as a model compound of dissolved organic matter, showed that the method is applicable to organic matter-containing waters without the addition of quinones.

  19. Antinociceptive action of (+/-)-cis-(6-ethyl-tetrahydropyran-2-yl)-formic acid in mice.

    PubMed

    Marinho, Bruno G; Miranda, Leandro S M; Gomes, Niele M; Matheus, Maria Eline; Leitão, Suzana G; Vasconcellos, Mario Luiz A A; Fernandes, Patrícia D

    2006-11-21

    The objective of this study was to investigate spinal and supraspinal antinociceptive effects of a new synthetic compound, (+/-)-cis-(6-ethyl-tetrahydropyran-2-yl)-formic acid (tetrahydropyran derivative). Its activity was compared with those from morphine. In peripheral models of inflammation and hyperalgesia, tetrahydropyran derivative significantly reduced nociceptive effect induced by acetic acid or formalin in mice. Tetrahydropyran derivative developed antinociceptive effect on the tail-flick and hot-plate tests with a long-acting curve maintaining the effect for 4 h longer than morphine. The opioid receptor antagonist naloxone totally reverted tetrahydropyran derivative effects on both models. Morphine as well as tetrahydropyran derivative induced tolerance and sedation in mice. However, tetrahydropyran derivative-induced tolerance had its onset retarded and the sedative activity was lower when compared to that induced by morphine. These results indicate that this new substance develops an antinociceptive activity and may be used in the future as a substitute for traditional opioids.

  20. An intercomparison of measurement systems for vapor and particulate phase concentrations of formic and acetic acids

    NASA Technical Reports Server (NTRS)

    Keene, William C.; Talbot, Robert W.; Andreae, Meinrat O.; Beecher, Kristene; Berresheim, Harold

    1989-01-01

    During June 1986, eight systems for measuring vapor phase and four for measuring particulate phase concentrations of formic acid (HCOOH) and acetic acid (CH3COOH) were intercompared in central Virginia. HCOOH and CH3COOH vapors were sampled by condensate, mist, Chromosorb 103 GC resin, NaOH-coated annular denuders, NaOH-impregnated quartz filters, K2CO3 and NaCO3-impregnated cellulose filters, and Nylasorb membranes. Atmospheric aerosol was collected on Teflon and Nuclepore filters using both hi-vol and lo-vol systems to measure particulate phase concentrations. Performances of the mist chamber and K2CO3-impregnated filter techniques were evaluated using zero air and ambient air spiked with HCOOH(g) and CH3COOH(g), and formaldehyde from permeation sources. The advantages and drawbacks of these methods are reported and discussed.

  1. An atom-economic approach to carboxylic acids via Pd-catalyzed direct addition of formic acid to olefins with acetic anhydride as a co-catalyst.

    PubMed

    Wang, Yang; Ren, Wenlong; Shi, Yian

    2015-08-21

    An effective Pd-catalyzed hydrocarboxylation of olefins using formic acid with acetic anhydride as a co-catalyst is described. A variety of carboxylic acids are obtained in good yields with high regioselectivities under mild reaction conditions without the use of toxic CO gas.

  2. Suppression of Growth Rate of Colony-Associated Fungi by High Fructose Corn Syrup Feeding Supplement, Formic Acid, and Oxalic Acid

    USDA-ARS?s Scientific Manuscript database

    Select colony-associated fungi (bee isolates). Absidia sp., Ascosphaera apis, Aspergillus flavus, Fusarium sp., Penicillium glabrum, Mucor sp., showed a 40% reduction in radial growth rate with formic acid, a 28% reduction with oxalic acid, and a 15% reduction with fructose and high fructose corn sy...

  3. A first principles study of the binding of formic acid in catalase complementing high resolution X-ray structures

    NASA Astrophysics Data System (ADS)

    Rovira, Carme; Alfonso-Prieto, Mercedes; Biarnés, Xevi; Carpena, Xavi; Fita, Ignacio; Loewen, Peter C.

    2006-03-01

    Density functional molecular dynamics simulations using a QM/MM approach are used to get insight into the binding modes of formic acid in catalase. Two ligand binding sites are found, named A and B, in agreement with recent high resolution structures of catalase with bound formic acid. In addition, the calculations show that the His56 residue is protonated and the ligand is present as a formate anion. The lowest energy minimum structure ( A) corresponds to the ligand interacting with both the heme iron and the catalytic residues (His56 and Asn129). The second minimum energy structure ( B) corresponds to the situation in which the ligand interacts solely with the catalytic residues. A mechanism for the process of formic acid binding in catalase is suggested.

  4. An effective Pd-Ni(2)P/C anode catalyst for direct formic acid fuel cells.

    PubMed

    Chang, Jinfa; Feng, Ligang; Liu, Changpeng; Xing, Wei; Hu, Xile

    2014-01-03

    The direct formic acid fuel cell is an emerging energy conversion device for which palladium is considered as the state-of-the-art anode catalyst. In this communication, we show that the activity and stability of palladium for formic acid oxidation can be significantly enhanced using nickel phosphide (Ni(2)P) nanoparticles as a cocatalyst. X-ray photoelectron spectroscopy (XPS) reveals a strong electronic interaction between Ni(2)P and Pd. A direct formic acid fuel cell incorporating the best Pd–Ni(2)P anode catalyst exhibits a power density of 550 mWcm(-2), which is 3.5 times of that of an analogous device using a commercial Pd anode catalyst.

  5. In situ surface-enhanced Raman spectroscopic study of formic acid electrooxidation on spontaneously deposited platinum on gold.

    PubMed

    Muralidharan, Ranjani; McIntosh, Michael; Li, Xiao

    2013-06-28

    Present formic acid fuel cell efficiency is limited by low kinetics at the anode, indicating the need for effective catalysts to improve the formic acid oxidation. As a prerequisite, the nature of adsorbed species and specifically the reaction intermediates formed in this process needs to be examined. This work focuses on the electrooxidation of formic acid and the nature of the intermediates at a platinum-modified gold surface prepared through spontaneous deposition using a combination of electrochemistry and in situ surface enhanced Raman spectroscopy (SERS). This Pt-modified gold electrode surface assists in oxidizing formic acid at potentials as low as 0.0 V vs. Ag/AgCl which is 0.15 V more negative than a bare Pt surface. The oxidation current obtained on the Pt-modified gold electrode is 72 times higher than on a bare Au surface and 5 times higher than on a bare Pt surface at the same potential. In situ SERS has revealed the involvement of formate at a low frequency as the primary intermediate in this electrooxidation process. While previous studies mainly focused on the formate mode at ca. 1322 cm(-1), it is the first time that a formate peak at ca. 300 cm(-1) was observed on a Pt or Pt-associated surface. A unique relationship has been observed between the formic acid oxidation currents and the SERS intensity of this formate adsorbate. Furthermore, the characteristic Stark effect of the formate proves the strong interaction between the adsorbate and the catalyst. Both electrochemical and spectroscopic results suggest that the formic acid electrooxidation takes place by the dehydrogenation pathway involving a low frequency formate intermediate on the Pt-modified gold electrode catalyst.

  6. Effective fall treatment of Varroa jacobsoni (Acari: Varroidae) with a new formulation of formic acid in colonies of Apis mellifera (Hymenoptera: Apidae) in the northeastern United States.

    PubMed

    Calderone, N W

    2000-08-01

    New formulations of formic acid and thymol, both individually and in combination with various essential oils, were compared with Apistan to determine their efficacy as fall treatments for control of Varroa jacobsoni (Oudemans), a parasitic mite of the honey bee, Apis mellifera L. Percent mite mortality in colonies treated with 300 ml of 65% formic acid averaged 94.2 +/- 1.41% (least square means +/- SE, n = 24), equivalent to those receiving four, 10% strips of Apistan (92.6 +/- 1.79%, n = 6). Treatment with thymol (n = 24) resulted in an average mite mortality of 75.4 +/- 5.79%, significantly less than that attained with Apistan or formic acid. The addition of essential oils did not affect treatment efficacy of either formic acid or thymol. The ratio of the coefficients of variation for percentage mortality for the formic acid (CVFA) and Apistan (CVA) groups was CVFA/CVA = 0.66. This indicates that the formic acid treatment was as consistent as the Apistan treatment. Thymol treatments did not provide as consistent results as Apistan or formic acid. Coefficient variation ratios for percentage mortality for the thymol group (CVT) with the Apistan and formic acid groups were CVT/CVA = 4.47 and CVT/CVFA = 6.76, respectively. In a second experiment, colonies received a 4-wk fall treatment of either 300 ml of 65% formic acid (n = 24) or four, 10% strips of Apistan (n = 6). The next spring, mite levels in the formic acid group (554.3 +/- 150.20 mites) were similar to those in the Apistan treatment group (571.3 +/- 145.05 mites) (P = 0.93). Additionally, the quantities of bees, brood, pollen, and nectar/honey in the two treatment groups were not significantly different (P > or = 0.50 each variable). These results suggest that formic acid is an effective alternative to Apistan as a fall treatment for varroa mites in temperate climates.

  7. Hydrogen production from formic acid in pH-stat fed-batch operation for direct supply to fuel cell.

    PubMed

    Shin, Jong-Hwan; Yoon, Jong Hyun; Lee, Seung Hoon; Park, Tai Hyun

    2010-01-01

    Enterobacter asburiae SNU-1 harvested after cultivation was used as a whole cell biocatalyst, for the production of hydrogen. Formic acid was efficiently converted to hydrogen using the harvested cells with an initial hydrogen production rate and total hydrogen production of 491 ml/l/h and 6668 ml/l, respectively, when 1 g/l of whole cell enzyme was used. Moreover, new pH-stat fed-batch operation was conducted, and total hydrogen production was 1.4 times higher than that of batch operation. For practical application, bio-hydrogen produced from formic acid using harvested cells was directly applied to PEMFC for power generation.

  8. Graphene decorated with PtAu alloy nanoparticles: facile synthesis and promising application for formic acid oxidation

    SciTech Connect

    Zhang, Sheng; Shao, Yuyan; Liao, Honggang; Liu, Jun; Aksay, Ilhan A.; Yin, Geping; Lin, Yuehe

    2011-03-01

    PtAu alloy nanoparticles (~ 3.2 nm in diameter) are synthesized in poly(diallyldimethylammonium chloride) (PDDA) aqueous solution and uniformly dispersed on graphene nanosheets. PtAu/graphene exhibits high electrocatalytic activity and stability for formic acid oxidation, which is attributed to the high dispersion of PtAu nanoparticles and the specific interaction between PtAu and graphene, indicating a promising catalyst for direct formic acid fuel cells. The facile method can be readily extended to the synthesis of other alloy nanoparticles.

  9. The size-controlled synthesis of Pd/C catalysts by different solvents for formic acid electrooxidation.

    PubMed

    Huang, Yunjie; Liao, Jianhui; Liu, Changpeng; Lu, Tianhong; Xing, Wei

    2009-03-11

    The size-controlled synthesis of Pd/C catalyst for formic acid electrooxidation is reported in this study. By using alcohol solvents with different chain length in the impregnation method, the sizes of Pd nanoparticles can be facilely tuned; this is attributed to the different viscosities of the solvents. The results show that a desired Pd/C catalyst with an average size of about 3 nm and a narrow size distribution is obtained when the solvent is n-butanol. The catalyst exhibits large electrochemically active surface area and high catalytic activity for formic acid electrooxidation.

  10. A DFT study on the catalytic hydrogenation of CO2 to formic acid over Ti-doped graphene nanoflake

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Dinparast, Leila

    2017-08-01

    The aim of this study is to investigate the potential of Ti-doped graphene nanoflake (Ti-GNF) for the reduction of CO2 to formic acid by H2. To get a deeper insight into the mechanism of this reaction, the reliable DFT calculations are performed. It is found that the large positive charge on the Ti atom can greatly regulate the surface reactivity of GNF. The formation of the formate group is the rate determining step for the reduction of CO2. The calculated activation energies demonstrate that Ti-GNF could be utilized as an efficient catalyst for the reduction of CO2 to formic acid.

  11. Intake, digestibility, and composition of orchardgrass and alfalfa silages treated with cellulase, inoculant, and formic acid fed to lambs.

    PubMed

    Nadeau, E M; Russell, J R; Buxton, D R

    2000-11-01

    The objectives of this study were to determine the effect of a cellulase (from Trichoderma longibrachiatum) alone or combined with a bacterial inoculant (Lactobacillus plantarum and Pediococcus cerevisiae) or formic acid on composition, intake, and digestibility of orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) silages. Orchardgrass and alfalfa were harvested at the early heading stage and at the early bloom stage of maturity and wilted to approximately 22 and 32% DM, respectively. Forages were then ensiled in 100-L sealed barrels for at least 60 d before they were fed to lambs. Silage treated with cellulase had lower (P < .001) pH and lower (P < .001) acetic acid and NH3 N concentrations than untreated silage of both plant species and a higher (P = .004) lactic acid concentration than the control treatment of alfalfa silage. Fermentation characteristics of cellulase-treated silages, especially of alfalfa, were further enhanced by use of inoculant. Formic acid addition increased (P < .001), reducing sugar concentration of cellulase-treated orchardgrass and alfalfa silage by 90 and 154%, respectively, and decreased (P < .001) NH3 N concentration of cellulase-treated alfalfa silage by 19%. Averaged across plant species, cellulase, combined with inoculant or formic acid, resulted in 8 and 13% greater (P = .03) DMI, respectively, than the control silage. Extensive enzymatic cell-wall degradation during ensiling decreased (P = .003) NDF intake of cellulase-treated orchardgrass silage by 25% and decreased (P = .001) cellulose intake by 23%, when averaged across plant species. Addition of formic acid increased (P = .003) NDF intake of cellulase-treated orchardgrass silage by 19%. Averaged across species, cellulase application decreased (P < .05) silage NDF digestibility by 18%. Greater sugar and lower acetic acid, NH3 N, and NDF concentrations resulted in greater DMI of cellulase-treated silage than of control silage, when cellulase was combined

  12. Formic and acetic acids in a nitrogen matrix: Enhanced stability of the higher-energy conformer

    NASA Astrophysics Data System (ADS)

    Lopes, Susy; Domanskaya, Alexandra V.; Fausto, Rui; Räsänen, Markku; Khriachtchev, Leonid

    2010-10-01

    Formic acid (HCOOH, FA) and acetic acid (CH3COOH, AA) are studied in a nitrogen matrix. The infrared (IR) spectra of cis and trans conformers of these carboxylic acids (and also of the HCOOD isotopologue of FA) are reported and analyzed. The higher-energy cis conformer of these molecules is produced by narrowband near-IR excitation of the more stable trans conformer, and the cis-to-trans tunneling decay is evaluated spectroscopically. The tunneling process in both molecules is found to be substantially slower in a nitrogen matrix than in rare-gas matrices, the cis-form decay constants being approximately 55 and 600 times smaller in a nitrogen matrix than in an argon matrix, for FA and AA respectively. The stabilization of the higher-energy cis conformer is discussed in terms of specific interactions with nitrogen molecule binding with the OH group of the carboxylic acid. This model is in agreement with the observed differences in the IR spectra in nitrogen and argon matrices, in particular, the relative frequencies of the νOH and τCOH modes and the relative intensities of the νOH and νCO bands.

  13. Production of hybrid diesel fuel precursors from carbohydrates and petrochemicals using formic acid as a reactive solvent.

    PubMed

    Zhou, Xiaoyuan; Rauchfuss, Thomas B

    2013-02-01

    We report the one-pot alkylation of mesitylene with carbohydrate-derived 5-(hydroxymethyl)furfural (HMF) as a step toward diesel-range liquids. Using FeCl(3) as a catalyst, HMF is shown to alkylate toluene, xylene, and mesitylene in high yields in CH(2)Cl(2) and MeNO(2) solvents. Efforts to extend this reaction to greener or safer solvents showed that most ether-based solvents are unsatisfactory. Acid catalysts (e.g, p-TsOH) also proved to be ineffective. Using formic acid as a reactive solvent, mesitylene could be alkylated to give mesitylmethylfurfural (MMF) starting from fructose with yields up to approximately 70 %. The reaction of fructose with formic acid in the absence of mesitylene gave rise to low yields of the formate ester of HMF, which indicates the stabilizing effect of replacing the hydroxyl substituent with mesityl. The arene also serves as a second phase into which the product is extracted. Even by using formic acid, the mesitylation of less expensive precursors such as glucose and cellulose proceeded only in modest yields (ca. 20 %). These simpler substrates were found to undergo mesitylation by using hydrogen chloride/formic acid via the intermediate chloromethylfurfural. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. High upward fluxes of formic acid from a boreal forest canopy

    SciTech Connect

    Schobesberger, Siegfried; Lopez-Hilfiker, Felipe D.; Taipale, Ditte; Millet, Dylan B.; D'Ambro, Emma L.; Rantala, Pekka; Mammarella, Ivan; Zhou, Putian; Wolfe, Glenn M.; Lee, Ben H.; Boy, Michael; Thornton, Joel A.

    2016-08-14

    Eddy covariance fluxes of formic acid, HCOOH, were measured over a boreal forest canopy in spring/summer 2014. The HCOOH fluxes were bidirectional but mostly upward during daytime, in contrast to studies elsewhere that reported mostly downward fluxes. Downward flux episodes were explained well by modeled dry deposition rates. The sum of net observed flux and modeled dry deposition yields an upward “gross flux” of HCOOH, which could not be quantitatively explained by literature estimates of direct vegetative/soil emissions nor by efficient chemical production from other volatile organic compounds, suggesting missing or greatly underestimated HCOOH sources in the boreal ecosystem. Here, we implemented a vegetative HCOOH source into the GEOS-Chem chemical transport model to match our derived gross flux and evaluated the updated model against airborne and spaceborne observations. Model biases in the boundary layer were substantially reduced based on this revised treatment, but biases in the free troposphere remain unexplained.

  15. Infrared and density functional theory studies of formic acid hydrate clusters in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Ito, Fumiyuki

    2016-08-01

    Infrared absorption spectra of formic acid hydrate clusters (HCOOH)m(H2O)n have been measured in noble gas matrices (Ar and Kr). The concentration dependence of the spectra and the comparison with a previous experimental study on HCOOH(H2O) and HCOOH(H2O)2 [Geoge et al., Spectrochim. Acta, Part A 60 (2004) 3225] led to the identification of large clusters. Density functional theory calculations at the B3LYP-DCP/6-31+G(2d,2p) level were carried out to determine the anharmonic vibrational properties of the clusters, enabling a consistent assignment of the observed vibrational peaks to specific clusters.

  16. Revealing the active intermediates in the oxidation of formic acid on Au and Pt(111).

    PubMed

    Gao, Wang; Song, Er Hong; Jiang, Qing; Jacob, Timo

    2014-08-25

    The mechanisms of formic acid (HCOOH) oxidation on Au(111) under gas-phase and electrochemical conditions was studied by using density functional theory and then compared with the analogous processes on Pt(111). Our results demonstrate that a mechanism involving a single intermediate molecule is preferred on both Au and Pt(111). Furthermore, under gas-phase conditions, HCOOH oxidation proceeds through the same mechanism (formate pathway) on Au and Pt(111), whereas under electrochemical conditions, it can take place through significantly different mechanisms (formate and/or direct pathways), depending on the applied electrode potential. Our calculations help to rationalize conflicting experimental explanations and are crucial for understanding the mechanism of this fundamental (electro-)catalytic process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Theoretical elucidation of the competitive electro-oxidation mechanisms of formic acid on Pt(111).

    PubMed

    Gao, Wang; Keith, John A; Anton, Josef; Jacob, Timo

    2010-12-29

    The mechanisms of formic acid (HCOOH) oxidation on Pt(111) under electrochemical conditions have been studied using density functional theory and then compared with the analogous gas-phase reaction. Results show that HCOOH oxidation under a water-covered surface behaves substantially differently than in the gas phase or using a solvation model involving only a few water molecules. Using these models, we evaluated the detailed reaction process, including energies and geometric structures of intermediates and transition states under the influence of different solvation models and electrode potentials. Our calculations indicate that this potential-dependent electrochemical oxidation proceeds via a multipath mechanism (involving both the adsorbed HCOOH and HCOO intermediates), a result succinctly rationalizing conflicting experimental observations. Moreover, this study highlights how subtle changes in electrochemical reaction environments can influence (electro)catalysis.

  18. Pd Nanoparticles Coupled to WO2.72 Nanorods for Enhanced Electrochemical Oxidation of Formic Acid.

    PubMed

    Xi, Zheng; Erdosy, Daniel P; Mendoza-Garcia, Adriana; Duchesne, Paul N; Li, Junrui; Muzzio, Michelle; Li, Qing; Zhang, Peng; Sun, Shouheng

    2017-04-12

    We synthesize a new type of hybrid Pd/WO2.72 structure with 5 nm Pd nanoparticles (NPs) anchored on 50 × 5 nm WO2.72 nanorods. The strong Pd/WO2.72 coupling results in the lattice expansion of Pd from 0.23 to 0.27 nm and the decrease of Pd surface electron density. As a result, the Pd/WO2.72 shows much enhanced catalysis toward electrochemical oxidation of formic acid in 0.1 M HClO4; it has a mass activity of ∼1600 mA/mgPd in a broad potential range of 0.4-0.85 V (vs RHE) and shows no obvious activity loss after a 12 h chronoamperometry test at 0.4 V. Our work demonstrates an important strategy to enhance Pd NP catalyst efficiency for energy conversion reactions.

  19. Energetics of methanol and formic acid oxidation on Pt(111): Mechanistic insights from adsorption calorimetry

    NASA Astrophysics Data System (ADS)

    Silbaugh, Trent L.; Karp, Eric M.; Campbell, Charles T.

    2016-08-01

    The catalytic and electrocatalytic oxidation and reforming of methanol and formic acid have received intense interest due to potential use in direct fuel cells and as prototype models for understanding electrocatalysis. Consequently, the reaction energy diagram (energies of all the adsorbed intermediates and activation energies of all the elementary steps) have been estimated for these reactions on Pt(111) by density functional theory (DFT) in several studies. However, no experimental measurement of these energy diagrams have been reported, nor is there a consensus on the mechanisms. Here, we use energies of key intermediates on Pt(111) from single crystal adsorption calorimetry (SCAC) and temperature programmed desorption (TPD) to build a combined energy diagram for these reactions. It suggests a new pathway involving monodentate formate as a key intermediate, with bidentate formate only being a spectator species that slows the rate. This helps reconcile conflicting proposed mechanisms.

  20. Oxidation of formic acid on the Pt(111) surface in the gas phase.

    PubMed

    Gao, Wang; Keith, John A; Anton, Josef; Jacob, Timo

    2010-09-28

    Formic acid (HCOOH) oxidation on Pt(111) under gas-phase conditions is a benchmark heterogeneous catalysis reaction used to probe electro-catalytic HCOOH conversion in fuel cells, itself an important reaction in energy conversion. We used density functional theory (DFT) calculations to elucidate the fundamental oxidation mechanisms of HCOOH in the gas phase, determining the relative strengths of chemical interactions between HCOOH oxidation intermediates and the Pt(111) surface. We focused on investigating how water and adsorption coverage affects reaction intermediate structures and transition states. Our results show that adsorbed HCOO is a reactive intermediate in gas phase, and co-adsorbed water plays a key role in HCOOH oxidation influencing the structure of reaction intermediates and reaction barriers on Pt(111). The simulations show the preferred catalytic pathway is qualitatively dependent on surface coverage. These results provide a conceptual basis to better interpret its complicated experimental reaction kinetics.

  1. Cellulose nanocrystals prepared via formic acid hydrolysis followed by TEMPO-mediated oxidation.

    PubMed

    Li, Bin; Xu, Wenyang; Kronlund, Dennis; Määttänen, Anni; Liu, Jun; Smått, Jan-Henrik; Peltonen, Jouko; Willför, Stefan; Mu, Xindong; Xu, Chunlin

    2015-11-20

    Cellulose nanocrystals (CNCs) as a renewable and biodegradable nanomaterial have wide application value. In this work, CNCs were extracted from bleached chemical pulp using two stages of isolation (i.e. formic acid (FA) hydrolysis and 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) mediated oxidation) under mild conditions. In the first stage, FA was used to remove hemicellulose, swell cellulose fibers, and release CNCs. The FA could be readily recovered and reused. In the second stage, the CNCs isolated by FA were further modified by TEMPO-mediated oxidation to increase the surface charge of CNCs. It was found that the modified CNCs with more ordered crystal structure and higher surface charge had better redispersibility and higher viscosity in aqueous phase. Therefore, the modified CNCs could be more effective when used as rheology modifier in the fields of water based coating, paint, food etc. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Synthesis of highly dispersed and active palladium/carbon nanofiber catalyst for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Qin, Yuan-Hang; Jiang, Yue; Yang, Hou-Hua; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2011-05-01

    Highly dispersed and active palladium/carbon nanofiber (Pd/CNF) catalyst is synthesized by NaBH4 reduction with trisodium citrate as the stabilizing agent. The obtained Pd/CNF catalyst is characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The results show that the Pd nanoparticles with an average particle size of ca. 3.8 nm are highly dispersed on the CNF support even with a small ratio of citrate to Pd precursor, which is believed to be due to the pH adjustment of citrate stabilized colloidal Pd nanoparticles. The cyclic voltammetry and chronoamperometry techniques show that the obtained Pd/CNF catalyst exhibits good catalytic activity and stability for the electrooxidation of formic acid.

  3. Microwave Measurements of Maleimide and its Doubly Hydrogen Bonded Dimer with Formic ACID*

    NASA Astrophysics Data System (ADS)

    Pejlovas, Aaron M.; Kang, Lu; Kukolich, Stephen G.

    2016-06-01

    The microwave spectra were measured for the maleimide monomer and the maleimide-formic acid doubly hydrogen bonded dimer using a pulsed-beam Fourier transform microwave spectrometer. Many previously studied doubly hydrogen bonded dimers are formed between oxygen containing species, so it is important to also characterize and study other dimers containing nitrogen, as hydrogen bonding interactions with nitrogen are found in biological systems such as in DNA. The transition state of the dimer does not exhibit C_2_V symmetry, so the tunneling motion was not expected to be observed based on the symmetry, but it would be very important to also observe the tunneling process for an asymmetric dimer. Single-line b-type transitions were observed, so the tunneling motion was not observed in our microwave spectra. The hydrogen bond lengths were determined using a nonlinear least squares fitting program. *Supported by the NSF CHE-1057796

  4. Reaction of Formic Acid over Amorphous Manganese Oxide Catalytic Systems: An In Situ Study

    SciTech Connect

    J Durand; S Senanayake; S Suib; D Mullins

    2011-12-31

    The interaction of formic acid with amorphous manganese oxide (AMO) is investigated using in situ photoelectron and infrared spectroscopy techniques. Soft X-ray photoelectron spectroscopy (sXPS) and in situ FTIR illustrate two possible modes of formate bound species at the AMO surface. Two peaks in the IR region from 1340-1390 cm{sup -1} are indicative of formate species bound to the surface in a bidentate configuration. However, a 224 cm{sup -1} band gap between v{sub s}OCO and v{sub as}OCO suggests formate is bound in a bridging configuration. Temperature-programmed desorption studies confirm the formate bound species desorbs as carbon dioxide from the surface at multiple binding sites. At temperatures above 700 K, the presence of K{sup +} {hor_ellipsis} OC complex suggests the bound species interacts at vacant sites related to framework oxygen and cation mobility.

  5. Reaction of Formic Acid over Amorphous Manganese Oxide Catalytic Systems: An In Situ Study

    SciTech Connect

    Durand, Jason; Senanayake, Sanjaya D; Mullins, David R; Suib, Steven

    2010-01-01

    The interaction of formic acid with amorphous manganese oxide (AMO) is investigated using in situ photoelectron and infrared spectroscopy techniques. Soft X-ray photoelectron spectroscopy (sXPS) and in situ FTIR illustrate two possible modes of formate bound species at the AMO surface. Two peaks in the IR region from 1340-1390 cm{sup -1} are indicative of formate species bound to the surface in a bidentate configuration. However, a 224 cm{sup -1} band gap between v{sub s}OCO and v{sub as}OCO suggests formate is bound in a bridging configuration. Temperature-programmed desorption studies confirm the formate bound species desorbs as carbon dioxide from the surface at multiple binding sites. At temperatures above 700 K, the presence of K{sup +} {hor_ellipsis} OC complex suggests the bound species interacts at vacant sites related to framework oxygen and cation mobility.

  6. Palladium nanoparticles supported on titanium doped graphitic carbon nitride for formic acid dehydrogenation.

    PubMed

    Wu, Yongmei; Wen, Meicheng; Navlani-García, Miriam; Kuwahara, Yasutaka; Mori, Kohsuke; Yamashita, Hiromi

    2017-02-28

    Pd nanoparticles (NPs) supported on Ti-doped graphitic carbon nitride (g-C₃N₄) were synthetised by a deposition-precipitation route and a subsequent reduction with NaBH₄. The features of Pd supported Ti-doped g-C₃N₄ were studied by XRD, TEM, FT-IR, XPS, EXAFS and N₂ physisorption measurements. It was found that the NPs had an average size of 2.9 nm and presented a high dispersion on the surface of Ti-doped g-C₃N₄. Compared with Pd loaded on pristine g-C₃N₄, Pd NPs supported Ti-doped g-C₃N₄ catalyst exhibited a high activity in formic acid dehydrogenation in water at room temperature. The enhanced activity can be attributed to the small Pd NPs size as well as the strong interaction between Pd NPs and Ti-doped g-C₃N₄.

  7. Asymmetric Transfer Hydrogenation of Imines in Water by Varying the Ratio of Formic Acid to Triethylamine.

    PubMed

    Shende, Vaishali S; Deshpande, Sudhindra H; Shingote, Savita K; Joseph, Anu; Kelkar, Ashutosh A

    2015-06-19

    Asymmetric transfer hydrogenation (ATH) of imines has been performed with variation in formic acid (F) and triethylamine (T) molar ratios in water. The F/T ratio is shown to affect both the reduction rate and enantioselectivity, with the optimum ratio being 1.1 in the ATH of imines with the Rh-(1S,2S)-TsDPEN catalyst. Use of methanol as a cosolvent enhanced reduction activity. A variety of imine substrates have been reduced, affording high yields (94-98%) and good to excellent enantioselectivities (89-98%). In comparison with the common azeotropic F-T system, the reduction with 1.1/1 F/T is faster.

  8. Hydrogen generation during treatment of simulated high-level radioactive waste with formic acid

    SciTech Connect

    Ritter, J.A.; Zamecnik, J.R.; Hsu, C.W.

    1992-01-01

    The Integrated Defense Waste Processing Facility (DWPF) Melter System (IDMS), operated by the Savannah River Laboratory, is a one-fifth scale pilot facility used in support of the start-up and operation of the Department of Energy's DWPF. Five IDMS runs determined the effect of the presence of noble metals in HLW sludge on the H{sub 2} generation rate during the preparation of melter feed with formic acid. Overall, the results clearly showed that H{sub 2} generation in the DWPF SRAT could, at times, exceed the lower flammable limit of H{sub 2} in air (4 vol%), depending on such factors as offgas generation and air inleakage of the DWPF vessels. Therefore, the installation of a forced air purge system and H{sub 2} monitors were recommended to the DWPF to control the generation of H{sub 2} during melter feed preparation by fuel dilution.

  9. Water-catalyzed gas-phase reaction of formic acid with hydroxyl radical: A computational investigation

    NASA Astrophysics Data System (ADS)

    Luo, Yi; Maeda, Satoshi; Ohno, Koichi

    2009-02-01

    The reaction of formic acid with hydroxyl radical, which is considered to be relevant to atmospheric chemistry, has been extensively studied. A water-catalyzed process of this reaction is computationally studied here for the first time. The scaled hypersphere search method was used for global exploration of pre-reaction complexes. Calculations were performed at high level of theory, such as CCSD(T)/cc-pVTZ//B3LYP/6-311+G(2df, 2p) and CCSD(T)/cc-pVTZ//MP2/aug-cc-pVDZ. It is found that the water-catalyzed process of this reaction is more kinetically favorable than its non-catalytic process. Such catalytic process may also be of interest for atmospheric chemistry, like the non-catalytic one.

  10. Hydrogen generation during treatment of simulated high-level radioactive waste with formic acid

    SciTech Connect

    Ritter, J.A.; Zamecnik, J.R.; Hsu, C.W.

    1992-05-01

    The Integrated Defense Waste Processing Facility (DWPF) Melter System (IDMS), operated by the Savannah River Laboratory, is a one-fifth scale pilot facility used in support of the start-up and operation of the Department of Energy`s DWPF. Five IDMS runs determined the effect of the presence of noble metals in HLW sludge on the H{sub 2} generation rate during the preparation of melter feed with formic acid. Overall, the results clearly showed that H{sub 2} generation in the DWPF SRAT could, at times, exceed the lower flammable limit of H{sub 2} in air (4 vol%), depending on such factors as offgas generation and air inleakage of the DWPF vessels. Therefore, the installation of a forced air purge system and H{sub 2} monitors were recommended to the DWPF to control the generation of H{sub 2} during melter feed preparation by fuel dilution.

  11. High upward fluxes of formic acid from a boreal forest canopy

    NASA Astrophysics Data System (ADS)

    Schobesberger, Siegfried; Lopez-Hilfiker, Felipe D.; Taipale, Ditte; Millet, Dylan B.; D'Ambro, Emma L.; Rantala, Pekka; Mammarella, Ivan; Zhou, Putian; Wolfe, Glenn M.; Lee, Ben H.; Boy, Michael; Thornton, Joel A.

    2016-09-01

    Eddy covariance fluxes of formic acid, HCOOH, were measured over a boreal forest canopy in spring/summer 2014. The HCOOH fluxes were bidirectional but mostly upward during daytime, in contrast to studies elsewhere that reported mostly downward fluxes. Downward flux episodes were explained well by modeled dry deposition rates. The sum of net observed flux and modeled dry deposition yields an upward "gross flux" of HCOOH, which could not be quantitatively explained by literature estimates of direct vegetative/soil emissions nor by efficient chemical production from other volatile organic compounds, suggesting missing or greatly underestimated HCOOH sources in the boreal ecosystem. We implemented a vegetative HCOOH source into the GEOS-Chem chemical transport model to match our derived gross flux and evaluated the updated model against airborne and spaceborne observations. Model biases in the boundary layer were substantially reduced based on this revised treatment, but biases in the free troposphere remain unexplained.

  12. Formic Acid: Development of an Analytical Method and Use as Process Indicator in Anaerobic Systems

    DTIC Science & Technology

    1992-03-01

    analysis #4 90 n < ic UU 0 4 0 00 < + zC 0C4 0 Lii+ /o oo 0 0 - 7/1 "Nw UI30 U 4Y X L L Hr>u- 4.2-Cmaio iOJwt O oCDn~ tomo 0 W 0 + I-. 0 + LL CD3 C- II ...OF TECHNOLOGY A UNIT OF THE UNIVERSITY SYSTEM OF GEORGIA SCHOOL OF CIVIL ENGINEERING ATLANTA, GEORGIA 30332 iIi ii FORMIC ACID: DEVELOPMENT OF AN...Dr. f.. Saunders II I I ACKNOWLEDGEMENT The completion of this research has been a very difficult, but at the same time rewarding task. i wish to

  13. Heterogeneous uptake and reactivity of formic acid on calcium carbonate particles: a Knudsen cell reactor, FTIR and SEM study.

    PubMed

    Al-Hosney, Hashim A; Carlos-Cuellar, Sofia; Baltrusaitis, Jonas; Grassian, Vicki H

    2005-10-21

    The heterogeneous uptake and reactivity of formic acid (HCOOH), a common gas-phase organic acid found in the environment, on calcium carbonate (CaCO(3)) particles have been investigated using a Knudsen cell reactor, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). FTIR measurements show that the adsorption of formic acid on the surface of calcium carbonate results in the formation of calcium formate. Besides calcium formate, carbonic acid is also a reaction product under dry conditions (<1% RH). Under dry conditions and at low pressures, the initial uptake coefficient of formic acid on CaCO(3) particles is measured to be 3 +/- 1 x 10(-3) and decreases as the surface saturates with adsorbed products. The maximum surface coverage of formic acid under dry conditions is determined to be (3 +/- 1)x 10(14) molecules cm(-2). Under humidified conditions (RH >10%), adsorbed water on the surface of the carbonate particles participates in the surface reactivity of these particles, which results in the enhanced uptake kinetics and extent of reaction of this organic acid on CaCO(3) as well as opens up several new reaction pathways. These reaction pathways include: (i) the water-assisted dissociation of carbonic acid to CO(2) and H(2)O and (ii) the formation of calcium formate islands and crystallites, as evident by SEM images. The results presented here show that adsorbed water plays a potentially important role in the surface chemistry of gas-phase organic acids on calcium carbonate particles.

  14. Homogeneous Catalysis for Sustainable Hydrogen Storage in Formic Acid and Alcohols.

    PubMed

    Sordakis, Katerina; Tang, Conghui; Vogt, Lydia K; Junge, Henrik; Dyson, Paul J; Beller, Matthias; Laurenczy, Gábor

    2017-10-06

    Hydrogen gas is a storable form of chemical energy that could complement intermittent renewable energy conversion. One of the main disadvantages of hydrogen gas arises from its low density, and therefore, efficient handling and storage methods are key factors that need to be addressed to realize a hydrogen-based economy. Storage systems based on liquids, in particular, formic acid and alcohols, are highly attractive hydrogen carriers as they can be made from CO2 or other renewable materials, they can be used in stationary power storage units such as hydrogen filling stations, and they can be used directly as transportation fuels. However, to bring about a paradigm change in our energy infrastructure, efficient catalytic processes that release the hydrogen from these molecules, as well as catalysts that regenerate these molecules from CO2 and hydrogen, are required. In this review, we describe the considerable progress that has been made in homogeneous catalysis for these critical reactions, namely, the hydrogenation of CO2 to formic acid and methanol and the reverse dehydrogenation reactions. The dehydrogenation of higher alcohols available from renewable feedstocks is also described. Key structural features of the catalysts are analyzed, as is the role of additives, which are required in many systems. Particular attention is paid to advances in sustainable catalytic processes, especially to additive-free processes and catalysts based on Earth-abundant metal ions. Mechanistic information is also presented, and it is hoped that this review not only provides an account of the state of the art in the field but also offers insights into how superior catalytic systems can be obtained in the future.

  15. Decomposition mechanism of formic acid on Cu (111) surface: A theoretical study

    NASA Astrophysics Data System (ADS)

    Jiang, Zhao; Qin, Pei; Fang, Tao

    2017-02-01

    The study of formic acid decomposition on transition metal surfaces is important to obtain useful information for vapor phase catalysis involving HCOOH and for the development of direct formic acid fuel cells. In this study, periodic density functional theory calculations have been employed to investigate the dissociation pathways of HCOOH on Cu (111) surface. About adsorption, it is found that the adsorption of HCOO, COOH, HCO, CO, OH and H on Cu (111) are considered chemisorption, whereas HCOOH, CO2, H2O and H2 have the weak interaction with Cu (111) surface. Furthermore, the minimum energy pathways are analyzed for the decomposition of HCOOH to CO2 and CO through the scission of Hsbnd O, Csbnd H and Csbnd O bonds. It is found that HCOOH, HCOO and COOH prefer to dissociate in the related reactions rather than desorb. For the decomposition, it is indicated that HCO and COOH are the main dissociated intermediates of trans-HCOOH, CO2 is the main dissociated intermediates of bidentate-HCOO, and CO is the main dissociated product of cis-COOH. The co-adsorbed H atom is beneficial for the formation of CO2 from cis-COOH. Besides, it is found that the most favorable path for HCOOH decomposition on Cu (111) surface is HCOOH-HCO-CO (Path 5), where the step of CO formation from HCO dehydrogenation is considered to be the rate-determining step. The results also show that CO is preferentially formed as the dominant product of HCOOH on Cu (111) surface.

  16. Photocatalytic activity of S- and F-doped TiO(2) in formic acid mineralization.

    PubMed

    Dozzi, Maria Vittoria; Livraghi, Stefano; Giamello, Elio; Selli, Elena

    2011-03-02

    Two series of doped titanium dioxide samples (S-TiO(2) and F-TiO(2)) were prepared by the sol-gel method in the presence of different amounts of dopant source (thiourea and NH(4)F, respectively), followed by calcination at 500, 600 or 700 °C, and characterised by BET, UV-vis absorption, XPS, HRTEM, XRD and EPR analyses. Reference undoped materials were prepared by the same synthetic procedure. Their photocatalytic activity under visible light was investigated employing the photocatalytic degradation of formic acid in aqueous suspension as test reaction. S-doped TiO(2) showed a photocatalytic activity quite similar to that of undoped materials. In this regard, the insertion of S, characterised by a relatively large ionic radius, into the TiO(2) crystalline structure appears rather difficult, as confirmed by XPS analysis. On the contrary, moderate F doping was beneficial in increasing the rate of formic acid photocatalytic degradation, especially for photocatalysts calcined at high temperature, consisting of highly crystalline pure anatase, in which the rate of detrimental charge carrier recombination was reduced. For both series of doped materials, high doping levels appear to limit the semiconductor photoactivity, probably due to the formation of a progressively increasing number of charge recombination centres. The EPR characterisation of the investigated doped TiO(2) samples evidenced the presence of nitrogen containing species (nitric oxide radical encapsulated in micro-void, with no photoactivity, and N(b)˙ species, active in visible light sensitisation) and of titanium reduced centres Ti(3+), due to charge imbalance consequent to dopant introduction in the TiO(2) lattice either in anionic (F(-)) or in cationic form (S(6+)).

  17. Enzyme, bacterial inoculant, and formic acid effects on silage composition of orchardgrass and alfalfa.

    PubMed

    Nadeau, E M; Buxton, D R; Russell, J R; Allison, M J; Young, J W

    2000-07-01

    We evaluated the effects of cellulase (from Trichoderma longibrachiatum) application rates on neutral detergent fiber (NDF) concentration and fermentation products of orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) silages harvested with decreasing dry matter (DM) digestibility. Additionally, the impacts of inoculant (Lactobacillus plantarum and Pediococcus cerevisiae), pectinase (from Aspergillus niger), or formic acid on silage composition were studied. Forages wilted to a DM content of about 320 g/kg were ensiled in laboratory silos for 60 d. Cellulase, combined with inoculant, was applied at 2, 10, and 20 ml/kg of herbage (at least 2500 IU/ml). Cellulase at 10 ml/kg was also applied alone or in combination with pectinase and inoculant or formic acid. The NDF concentration of orchardgrass silage decreased with increasing cellulase up to 20 ml/kg, at which NDF content was decreased by 30%. The NDF concentration of alfalfa silage decreased with increasing cellulase application up to 10 ml/kg, at which NDF content was decreased by 13%. Immature plants were more responsive to cellulase treatment than mature plants. Cellulase at 2 ml/kg combined with inoculant improved fermentation characteristics of the silages but generally, there was no effect on silage fermentation by higher cellulase applications, resulting in an accumulation of sugar. The improved fermentation of orchardgrass treated with cellulase and inoculant was mostly related to the effect of inoculant, whereas cellulase alone improved fermentation characteristics of alfalfa silage and this effect was enhanced by addition of inoculant. Decreased NDF and increased sugar concentrations did not improve the in vitro DM digestibility of cellulase-treated silages.

  18. In vitro assessment of the effect of methanol and the metabolite, formic acid, on embryonic development of the rat.

    PubMed

    Brown-Woodman, P D; Huq, F; Hayes, L; Herlihy, C; Picker, K; Webster, W S

    1995-10-01

    Inhalation studies in rats have indicated that methanol is embryotoxic at levels that are only mildly maternally toxic. In the present study, the embryotoxicity of methanol and its metabolite, formic acid, was evaluated using rat embryo culture. The results showed that both methanol and formic acid have a concentration-dependent embryotoxic effect on the developing rat embryo in vitro. The no-effect concentration of methanol was 211.7 mumol/ml culture medium, while embryotoxicity was observed at 286.5 mumol/ml. The no-effect concentration of formic acid was 3.74 mumol/ml, while a concentration of 18.66 mumol/ml was associated with severe embryotoxicity. When embryos were grown in sera containing 18.66 mumol sodium formate/ml or in sera adjusted with hydrochloric acid to pH values similar to those achieved with formic acid, the results indicated that both low pH and formate contributed to the observed embryotoxicity of formic acid. When the level of methanol found to be embryotoxic in the present study is compared to blood levels in the human following controlled industrial exposure there appears to be a large margin of safety. However, plasma methanol levels are only one aspect of methanol toxicity in the human. Of greater significance is the formate level and the associated acidosis. However, it appears that embryotoxicity due to low pH or high formate levels would only occur after very severe methanol intoxication. Based on these in vitro studies, current industrial safety limits would appear to provide protection for the developing embryo.

  19. Hydrogenation of CO2 to Formic Acid with a Highly Active Ruthenium Acriphos Complex in DMSO and DMSO/Water

    PubMed Central

    Rohmann, Kai; Kothe, Jens; Haenel, Matthias W.; Englert, Ulli; Hölscher, Markus

    2016-01-01

    Abstract The novel [Ru(Acriphos)(PPh3)(Cl)(PhCO2)] [1; Acriphos=4,5‐bis(diphenylphosphino)acridine] is an excellent precatalyst for the hydrogenation of CO2 to give formic acid in dimethyl sulfoxide (DMSO) and DMSO/H2O without the need for amine bases as co‐reagents. Turnover numbers (TONs) of up to 4200 and turnover frequencies (TOFs) of up to 260 h−1 were achieved, thus rendering 1 one of the most active catalysts for CO2 hydrogenations under additive‐free conditions reported to date. The thermodynamic stabilization of the reaction product by the reaction medium, through hydrogen bonds between formic acid and clusters of solvent or water, were rationalized by DFT calculations. The relatively low final concentration of formic acid obtained experimentally under catalytic conditions (0.33 mol L−1) was shown to be limited by product‐dependent catalyst inhibition rather than thermodynamic limits, and could be overcome by addition of small amounts of acetate buffer, thus leading to a maximum concentration of free formic acid of 1.27 mol L−1, which corresponds to optimized values of TON=16×103 and TOFavg≈103 h−1. PMID:27356513

  20. Highly efficient hydrogen generation from formic acid using a reduced graphene oxide-supported AuPd nanoparticle catalyst.

    PubMed

    Yang, Xinchun; Pachfule, Pradip; Chen, Yao; Tsumori, Nobuko; Xu, Qiang

    2016-03-18

    Highly dispersed AuPd alloy nanoparticles have been successfully immobilized on reduced graphene oxide (rGO) using a facile non-noble metal sacrificial method, which exhibit the highest activity at 323 K (turnover frequency, 4840 h(-1)) for hydrogen generation without CO impurity from the formic acid/sodium formate system.

  1. Amine-borane assisted synthesis of wavy palladium nanorods on graphene as efficient catalysts for formic acid oxidation.

    PubMed

    Du, Cheng; Liao, Yuxiang; Hua, Xing; Luo, Wei; Chen, Shengli; Cheng, Gongzhen

    2014-11-04

    Wavy palladium (Pd) nanorods were obtained by controlled synthesis by using amine-boranes as the reducing agents. Thanks to the unique structure and strong interaction with graphene, the as-synthesized Pd nanorods supported on graphene exhibit much enhanced electrocatalytic activity towards formic acid oxidation as compared with Pd nanoparticles.

  2. Enhanced formic acid oxidation on polycrystalline platinum modified by spontaneous deposition of gold. Fourier transform infrared spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Cappellari, Paula S.; García, Gonzalo; Florez-Montaño, Jonathan; Barbero, Cesar A.; Pastor, Elena; Planes, Gabriel A.

    2015-11-01

    Formic acid and adsorbed carbon monoxide electrooxidation on polycrystalline Pt and Au-modified Pt surfaces were studied by cyclic voltammetry, lineal sweep voltammetry and in-situ Fourier transform infrared spectroscopy techniques. With this purpose, a polycrystalline Pt electrode was modified by spontaneous deposition of gold atoms, achieving a gold surface coverage (θ) in the range of 0 ≤ θ ≤ 0.47. Results indicate the existence of two main pathways during the formic acid oxidation reaction, i.e. dehydration and dehydrogenation routes. At higher potentials than 0.5 V the dehydrogenation pathway appears to be the operative at both Pt and Au electrodes. Meanwhile, the dehydration reaction is the main pathway for Pt at lower potentials than 0.5 V. It was found that reaction routes are easily tuned by Au deposition on the Pt sites responsible for the formic acid dehydration reaction, and hence for the catalytic formation of adsorbed carbon monoxide. Gold deposition on these Pt open sites produces an enhanced activity toward the HCOOH oxidation reaction. In general terms, the surface inhibition of the reaction by adsorbed intermediates (indirect pathway) is almost absent at gold-modified Pt electrodes, and therefore the direct pathway appears as the main route during the formic acid electrooxidation reaction.

  3. Single-crystalline Pd square nanoplates enclosed by {100} facets on reduced graphene oxide for formic acid electro-oxidation.

    PubMed

    Jiang, Yi; Yan, Yucong; Chen, Wenlong; Khan, Yousaf; Wu, Jianbo; Zhang, Hui; Yang, Deren

    2016-12-06

    Single-crystalline Pd square nanoplates enclosed by {100} facets were generated on reduced graphene oxide and exhibited the substantially enhanced properties for the formic acid oxidation reaction. The combination of carbonyl groups formed on the surface of annealed graphene oxide and Br(-) ions played important roles in this synthesis.

  4. One-pot synthesis of single-crystalline PtPb nanodendrites with enhanced activity for electrooxidation of formic acid.

    PubMed

    Qu, Ximing; Cao, Zhenming; Zhang, Binwei; Tian, XiaoChun; Zhu, Fuchun; Zhang, Zongcheng; Jiang, Yanxia; Sun, Shigang

    2016-03-25

    Bimetallic PtPb nanodendrites with a single-crystalline structure were obtained by a facile one-pot strategy. The as-synthesized dendritic structure was well characterized and the growth mechanism was investigated. PtPb nanodendrites exhibited superior activity (5.1 times higher than commercial Pd black) and strong anti-poisoning ability for electrooxidation of formic acid.

  5. Enhanced catalytic performance of carbon supported palladium nanoparticles by in-situ synthesis for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Yao, Shikui; Li, Guoqiang; Liu, Changpeng; Xing, Wei

    2015-06-01

    The development of facile, surfactant-free strategy for the scale-up production of catalysts with superior performance for energy science is an interesting challenge. Pd/C is synthesized using an in-situ method from PdO/C for formic acid electrooxidation based on the reducibility of formic acid. The morphology, composition and electrocatalytic properties are investigated using transmission electronmicroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, linear scan voltammograms (LSV) and chronoamperometry. The in-situ synthesized Pd nanoparticles show better distribution and smaller average particle size than the normally synthesized Pd/C, which indicates that the well-known Ostwald ripening is most limited in the synthesis process. The electrochemical measurements show that the Pd/C catalyst exhibits enhanced performance towards formic acid electrooxidation. For example, the peak current of the Pd/C catalyst is approximately three times that of the homemade Pd/C catalyst and twice as high as that of the commercial Pd/C catalyst in the LSV test. The in-situ synthesized Pd/C catalyst has potential application for direct formic acid fuel cells, and the in-situ route should be an effective strategy to synthesize high performance catalysts.

  6. Hydrogenation of CO2 to Formic Acid with a Highly Active Ruthenium Acriphos Complex in DMSO and DMSO/Water.

    PubMed

    Rohmann, Kai; Kothe, Jens; Haenel, Matthias W; Englert, Ulli; Hölscher, Markus; Leitner, Walter

    2016-07-25

    The novel [Ru(Acriphos)(PPh3 )(Cl)(PhCO2 )] [1; Acriphos=4,5-bis(diphenylphosphino)acridine] is an excellent precatalyst for the hydrogenation of CO2 to give formic acid in dimethyl sulfoxide (DMSO) and DMSO/H2 O without the need for amine bases as co-reagents. Turnover numbers (TONs) of up to 4200 and turnover frequencies (TOFs) of up to 260 h(-1) were achieved, thus rendering 1 one of the most active catalysts for CO2 hydrogenations under additive-free conditions reported to date. The thermodynamic stabilization of the reaction product by the reaction medium, through hydrogen bonds between formic acid and clusters of solvent or water, were rationalized by DFT calculations. The relatively low final concentration of formic acid obtained experimentally under catalytic conditions (0.33 mol L(-1) ) was shown to be limited by product-dependent catalyst inhibition rather than thermodynamic limits, and could be overcome by addition of small amounts of acetate buffer, thus leading to a maximum concentration of free formic acid of 1.27 mol L(-1) , which corresponds to optimized values of TON=16×10(3) and TOFavg ≈10(3)  h(-1) .

  7. Direction to practical production of hydrogen by formic acid dehydrogenation with Cp*Ir complexes bearing imidazoline ligands

    DOE PAGES

    Onishi, Naoya; Ertem, Mehmed Z.; Xu, Shaoan; ...

    2016-11-10

    In a Cp*Ir complex with a bidentate pyridyl-imidazoline ligand achieved the evolution of 1.02 m3 of H2/CO2 gases by formic acid dehydrogenation without any additives or adjustments in the solution system. Furthermore, the pyridyl-imidazoline moieties provided the optimum pH to be 1.7, resulting in high activity and stability even at very acidic conditions.

  8. Direction to practical production of hydrogen by formic acid dehydrogenation with Cp*Ir complexes bearing imidazoline ligands

    SciTech Connect

    Onishi, Naoya; Ertem, Mehmed Z.; Xu, Shaoan; Tsurusaki, Akihiro; Manaka, Yuichi; Muckerman, James T.; Fujita, Etsuko; Himeda, Yuichiro

    2016-11-10

    In a Cp*Ir complex with a bidentate pyridyl-imidazoline ligand achieved the evolution of 1.02 m3 of H2/CO2 gases by formic acid dehydrogenation without any additives or adjustments in the solution system. Furthermore, the pyridyl-imidazoline moieties provided the optimum pH to be 1.7, resulting in high activity and stability even at very acidic conditions.

  9. One-pot transformation of cellobiose to formic acid and levulinic acid over ionic-liquid-based polyoxometalate hybrids.

    PubMed

    Li, Kaixin; Bai, Linlu; Amaniampong, Prince Nana; Jia, Xinli; Lee, Jong-Min; Yang, Yanhui

    2014-09-01

    Currently, levulinic acid (LA) and formic acid (FA) are considered as important carbohydrates for the production of value-added chemicals. Their direct production from biomass will open up a new opportunity for the transformation of biomass resource to valuable chemicals. In this study, one-pot transformation of cellobiose into LA and FA was demonstrated, using a series of multiple-functional ionic liquid-based polyoxometalate (IL-POM) hybrids as catalytic materials. These IL-POMs not only markedly promoted the production of valuable chemicals including LA, FA and monosaccharides with high selectivities, but also provided great convenience of the recovery and the reuse of the catalytic materials in an environmentally friendly manner. Cellobiose conversion of 100%, LA selectivity of 46.3%, and FA selectivity of 26.1% were obtained at 423 K and 3 MPa for 3 h in presence of oxygen. A detailed catalytic mechanism for the one-pot transformation of cellobiose was also presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Highly active carbon supported Pd cathode catalysts for direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Mikolajczuk-Zychora, A.; Borodzinski, A.; Kedzierzawski, P.; Mierzwa, B.; Mazurkiewicz-Pawlicka, M.; Stobinski, L.; Ciecierska, E.; Zimoch, A.; Opałło, M.

    2016-12-01

    One of the drawbacks of low-temperature fuel cells is high price of platinum-based catalysts used for the electroreduction of oxygen at the cathode of the fuel cell. The aim of this work is to develop the palladium catalyst that will replace commonly used platinum cathode catalysts. A series of palladium catalysts for oxygen reduction reaction (ORR) were prepared and tested on the cathode of Direct Formic Acid Fuel Cell (DFAFC). Palladium nanoparticles were deposited on the carbon black (Vulcan) and on multiwall carbon nanotubes (MWCNTs) surface by reduction of palladium(II) acetate dissolved in ethanol. Hydrazine was used as a reducing agent. The effect of functionalization of the carbon supports on the catalysts physicochemical properties and the ORR catalytic activity on the cathode of DFAFC was studied. The supports were functionalized by treatment in nitric acid for 4 h at 80 °C. The structure of the prepared catalysts has been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV). Hydrophilicity of the catalytic layers was determined by measuring contact angles of water droplets. The performance of the prepared catalysts has been compared with that of the commercial 20 wt.% Pt/C (Premetek) catalyst. The maximum power density obtained for the best palladium catalyst, deposited on the surface of functionalized carbon black, is the same as that for the commercial Pt/C (Premetek). Palladium is cheaper than platinum, therefore the developed cathode catalyst is promising for future applications.

  11. Effect of ultrasonic frequency on the mechanism of formic acid sonolysis.

    PubMed

    Navarro, Nathalie M; Chave, Tony; Pochon, Patrick; Bisel, Isabelle; Nikitenko, Sergey I

    2011-03-10

    The kinetics and mechanism of formic acid sonochemical degradation were studied at ultrasonic frequencies of 20, 200, and 607 kHz under argon atmosphere. Total yield of HCOOH sonochemical degradation increases approximately 6-8-fold when the frequency increased from 20 to 200 or to 607 kHz. At low ultrasonic frequencies, HCOOH degradation has been attributed to oxidation with OH(•) radicals from water sonolysis and to the HCOOH decarboxylation occurring at the cavitation bubble-liquid interface. With high-frequency ultrasound, the sonochemical reaction is also influenced by HCOOH dehydration. Whatever the ultrasonic frequency, the sonolysis of HCOOH yielded H(2) and CO(2) in the gas phase as well as trace amounts of oxalic acid and formaldehyde in the liquid phase. However, CO and CH(4) formations were only detected under high-frequency ultrasound. The most striking difference between low-frequency and high-frequency ultrasound is that the sonolysis of HCOOH at high ultrasonic frequencies initiates Fischer-Tropsch hydrogenation of carbon monoxide. © 2011 American Chemical Society

  12. Au-supported Pt-Au mixed atomic monolayer electrocatalyst with ultrahigh specific activity for oxidation of formic acid in acidic solution.

    PubMed

    Huang, Zhao; Liu, Yan; Xie, Fangyun; Fu, Yingchun; He, Yong; Ma, Ming; Xie, Qingji; Yao, Shouzhuo

    2012-12-25

    Au-supported Pt-Au mixed atomic monolayer electrocatalyst was prepared by underpotential deposition of Cu on Au and then redox replacement with noble metal atoms, which shows an ultrahigh Pt-mass (or Pt-area) normalized specific electrocatalytic activity of 102 mA μg(Pt)(-1) (124 mA cm(Pt)(-2)) for oxidation of formic acid in acidic aqueous solution.

  13. In situ decarboxylation of acetic and formic acids in aqueous inclusions as a possible way to produce excess CH4

    NASA Astrophysics Data System (ADS)

    Ong, Anthony; Pironon, Jacques; Robert, Pascal; Dubessy, Jean; Caumon, Marie-Camille; Randi, Aurélien; Chailan, Olivier; Girard, Jean-Pierre

    2013-04-01

    Accurate reconstruction of diagenetic P-T conditions in petroleum reservoirs from fluid inclusion data relies on valid measurements of methane concentration in aqueous inclusions. Techniques have been developed (Raman spectrometry) to provide sufficiently accurate data, assuming measured methane concentration has not been modified after aqueous inclusion entrapment. In petroleum reservoirs, acetic (CH3COOH) and formic (HCOOH) acids are the most commonly reported organic acids, and the concentration of the total organic acids can be as high as 10,000 ppm at temperature below 120°C. This study investigates the likelihood that organic acids derived from petroleum fluids and dissolved in formation water might suffer decarboxylation upon post-entrapment heating within the fluid inclusion chamber upon post-entrapment heating, thereby generating excess CH4 in the inclusions. Four different experiments were conducted in Fused Silica Capillary Capsules (FSCCs), mimicking fluid inclusions. The capsules were loaded with acetic (CH3COOH) or formic (HCOOH) acid solution and were heated to 250°C for short durations (< 72hrs) in closed system conditions, with or without applying a fixed PH2. Reaction products were characterized by Raman and FT-IR spectrometry. The beginning of the decarboxylation of acetic acid is reached in 32 h at 250°C, with production of CH4 and CO2. Complete decarboxylation of formic acid is reached in 5 h at 250°C, with production of CO2, CO and H2. The lack of CH4 production in experiments with formic acid may be attributed to the relatively short duration of the experiments and/or the loss of H2 through the FSCC by diffusion during the experiment. Further experiments with a longer heating duration should be performed to assess the possibility of reducing the CO2 into CH4 from the formic acid. 2) The injection of H2 in the FSCC as a way to promote CO2 reduction did not promote decarboxylation in the duration of our experiment. These results suggest

  14. Simultaneous Determination of Methanol, Ethanol and Formic Acid in Serum and Urine by Headspace GC-FID.

    PubMed

    Bursová, Miroslava; Hložek, Tomáš; Čabala, Radomír

    2015-01-01

    A simple, cost-effective headspace gas chromatography (GC) method coupled with GC with flame ionization detection for simultaneous determination of methanol, ethanol and formic acid was developed and validated for clinical and toxicological purposes. Formic acid was derivatized with an excess of isopropanol under acidic conditions to its volatile isopropyl ester while methanol and ethanol remained unchanged. The entire sample preparation procedure is complete within 6 min. The design of the experiment (the face-centered central composite design) was used for finding the optimal conditions for derivatization, headspace sampling and chromatographic separation. The calibration dependences of the method were quadratic in the range from 50 to 5,000 mg/L, with adequate accuracy (89.0-114.4%) and precision (<12%) in the serum. The new method was successfully used for determination of selected analytes in serum samples of intoxicated patients from among those affected by massive methanol poisonings in the Czech Republic in 2012.

  15. Significant sensitivity improvement of alternating current driven-liquid discharge by using formic acid medium for optical determination of elements.

    PubMed

    Xiao, Qing; Zhu, Zhenli; Zheng, Hongtao; He, Haiyang; Huang, Chunying; Hu, Shenghong

    2013-03-15

    A method has been developed to improve the performance of alternating-current electrolyte atmospheric liquid discharge (ac-EALD) optical emission spectrometry for the determination of elements. Significant enhancement of emission intensity was achieved by adding organic substance into the nitric acid electrolyte solutions. Under the optimized conditions, 3% (v/v) formic acid in nitric acid (pH 1.0) produced 13 times enhancement for Ag and 7% (v/v) formic acid resulted in 17 times enhancement for Cd. The emission of Pb was even enhanced 78 times in the presence of 3% formic acid. In addition, the signal stability was also improved compared with that in the absence of organic substances. Repeatability was 0.8% for 0.1 mg L(-1) Ag, 0.7% for 0.2 mg L(-1) Cd and 2.6% for 1 mg L(-1) Pb standard solutions (n=5). The limits of detection of Ag, Cd and Pb were 1, 17 and 45 μg L(-1), respectively. The accuracy of the method was demonstrated by determination of elements in simulated natural water samples (GBW(E)080402 and GBW(E)080399).

  16. [Fermentation process during the ensiling of green forage low in nitrate. 2. Fermentation process after supplementation of nitrate, nitrite, lactic acid bacteria and formic acid].

    PubMed

    Kaiser, E; Weiss, K

    1997-01-01

    The effect of adding nitrate and nitrite (0.05% and 0.01% N in DM) of two inoculants or formic acid on the ensiling of orchardgrass and a grass-legumes-mixture, both low in nitrate, was proved in two experiments during ensiling starting in an early stage of fermentation silages without additives contained butyric acid, with increasing amounts up to 180 day of storage period. Silages with added nitrate or nitrite (0.1% N in DM) contained no butyric acid despite of a delay in the formation of lactic acid Nitrite was more effective as nitrate (both 0.05% N in DM) to suppress butyric acid fermentation. However, both additives, nitrite and nitrate, increased the lactic acid fermentation. Interpreting this facts it was hypothesized that the clostridia was inhibited by nitrate and nitrite. Addition of inoculants improved the formation of lactic acid, and decreased pH-value in comparison to control silages. The formation of butyric acid was limited, but not suppressed. The effect of inoculants differed in the intensity of fermentation and the formation of by-products of lactic acid fermentation. The effect of formic acid was not sure.

  17. Exchange of atmospheric formic and acetic acids with trees and crop plants under controlled chamber and purified air conditions

    NASA Astrophysics Data System (ADS)

    Kesselmeier, J.; Bode, K.; Gerlach, C.; Jork, E.-M.

    We investigated the exchange of formic and acetic acids between the atmosphere and various tree species such as beech ( Fagus sylvatica L.), ash ( Fraxinus excelsior L.), spruce ( Picea abies L.) Karst, holm oak ( Quercus ilex L.), and birch ( Betula pendula L.). and some crop-plant species such as corn ( Zea mays, var. Banjo), pea ( Pisum sativum, var. Solara), barley ( Hordeum vulgare, var. Igri) and oat (Avena sativa, var. Wiesel). All experiments were done with dynamic enclosures flushed with purified oxidant-free air, containing only low or controlled amounts of the two acids. Significant and light-triggered emission of both acids from all tree species was observed. For one tree species (ash) a seasonal large increase in fall due to early leaf decomposition was found. The standard emission factors (30°C and PAR=1000 μmol m 2 s -1) given as (nmol m -2 min -1) for acetic and formic acids, respectively, were 8.1 and 29.7 (ash, autumn), 1.0 and 3.3 (ash, summer), 0.9 and 1.4 (beech), 0.7 and 1.45 (spruce), 1.9 and 2.4 (Holm oak) and 1.7 and 6.7 (birch). Rough estimation of global annual emissions range between 20 and 130 Gmol formic acid and 10 and 33 Gmol acetic acid. These numbers reflect a 15-30% contribution by forest emissions to the continental organic acid budget. As compared to the global total NMHC emissions low molecular weight organic acids are of minor importance. In contrast to the trees, none of the crop-plant species investigated showed an emission, but always a clear deposition of both acids. Both emission from trees as well as uptake by the agricultural plants could be related to transpiration rates and leaf conductances.

  18. High Upward Fluxes of Formic Acid from a Boreal Forest Canopy

    NASA Astrophysics Data System (ADS)

    Schobesberger, S.; Lopez-Hilfiker, F.; Taipale, D.; Millet, D. B.; D'Ambro, E.; Mammarella, I.; Zhou, P.; Wolfe, G.; Lee, B. H.; Boy, M.; Thornton, J. A.

    2016-12-01

    Formic acid, HCOOH, is one of the most abundant carboxylic acids found in the atmosphere, affecting cloud chemistry and acidity, and as a common product in the oxidative processing of volatile organic compounds (VOC), it provides constraints on the importance of various pathways and precursors. Yet, significant uncertainties in the sources and sinks of HCOOH concentrations remain. We present measurements of HCOOH mixing ratios and eddy fluxes over a boreal forest canopy in spring/summer. Boreal forests have been identified as a key region for much of the global production of HCOOH, as well as for our lack of understanding of the underlying processes. To our knowledge, these are the first direct measurements of HCOOH exchange above a boreal forest ecosystem. The measured HCOOH fluxes were bidirectional, but mostly upward during daytime, in contrast to studies made elsewhere that reported mostly downward fluxes. Episodes of downward flux were explained well by standard resistor models of dry deposition. The sum of net observed flux and modeled deposition yields an upward "gross flux" of HCOOH, which could not be quantitatively explained by literature estimates of direct vegetative/soil emissions nor by efficient chemical production from other VOC (e.g. monoterpenes). These observations suggest greatly underestimated HCOOH sources, by up to a factor of 10, of biogenic origin in the boreal forest. We implemented a vegetative HCOOH source into the GEOS-Chem chemical transport model to match our derived gross flux, and evaluated the updated model against air- and space-borne HCOOH observations. Model biases in the boundary layer were substantially reduced based on this revised treatment, suggesting that a significant fraction of the missing HCOOH source in boreal regions is located within or just above the forest canopy. Biases in the free troposphere remain unexplained.

  19. The Jet-Cooled High-Resolution IR Spectrum of Formic Acid Cyclic Dimer

    NASA Astrophysics Data System (ADS)

    Goubet, Manuel; Bteich, Sabath; Huet, Therese R.; Pirali, Olivier; Asselin, Pierre; Soulard, Pascale; Jabri, Atef; Roy, P.; Georges, Robert

    2017-06-01

    As the simplest carboxylic acid, formic acid (FA) is an excellent model molecule to investigate the general properties of carboxylic acids. FA is also an atmospherically and astrophysically relevant molecule. It is well known that its dimeric form is predominant in the gas phase at temperatures below 423 K. The cyclic conformation of the dimer (FACD) is an elementary system to be understood for the concerted hydrogen transfer through equivalent hydrogen bonds, an essential process within biomolecules. The IR range is a crucial spectral region, particularly the far-IR, as it gives a direct access to the intermolecular vibrational modes involved in this process. Moreover, due to its centrosymmetric conformation, the FACD exhibits no pure rotation spectrum and, due to spectral line congestion and Doppler broadening, IR bands cannot be rotationally resolved at room temperature. So far, only parts of the ν_{5}-GS band (C-O stretch) have been observed under jet-cooled conditions using laser techniques. We present here six rotationally resolved IR bands of FACD recorded under jet-cooled conditions using the Jet-AILES apparatus and the QCL spectrometer at MONARIS, including the far-IR ν_{24}-GS band (intermolecular in-plane bending). Splitting due to vibration-rotation-tunneling motions are clearly observed. A full spectral analysis is in progress starting from the GS constants obtained by Goroya et al. and with the support of electronic structure calculations. T. Miyazawa and K. S. Pitzer, J. Am. Chem. Soc. 81, 74, 1959 R. Georges, M. Freytes, D. Hurtmans, I. Kleiner, J. Vander Auwera, M. Herman, Chem. Phys. 305, 187, 2004 M. Ortlieb and M. Havenith, J. Phys. Chem. A 111, 7355, 2007; K. G. Goroya, Y. Zhu, P. Sun and C. Duan, J. Chem. Phys. 140, 164311, 2014 This work is supported by the CaPPA project (Chemical and Physical Properties of the Atmosphere) ANR-11-LABX-0005-01

  20. A novel photoelectrochemical flow cell with online mass spectrometric detection: oxidation of formic acid on a nanocrystalline TiO2 electrode.

    PubMed

    Reichert, Robert; Jusys, Zenonas; Behm, R Jürgen

    2014-12-07

    A novel thin-layer photoelectrochemical flow cell allowing the online mass spectrometric detection of volatile reaction products during photoelectrocatalytic reactions has been developed and applied for separating the contributions from photoelectrochemical water splitting and photoelectrooxidation of formic acid to the overall photocurrent in formic acid containing aqueous solution, using a nanocrystalline TiO2 (P25) thin-film electrode. The data reveal a clear suppression of the water oxidation reaction to O2 in the presence of formic acid. Advantages of this flow cell design over conventional photoelectrochemical cells with stagnant electrolyte in terms of mass transport will be demonstrated and discussed.

  1. Formic acid electrooxidation on thallium-decorated shape-controlled platinum nanoparticles: an improvement in electrocatalytic activity.

    PubMed

    Busó-Rogero, Carlos; Perales-Rondón, Juan V; Farias, Manuel J S; Vidal-Iglesias, Francisco J; Solla-Gullon, Jose; Herrero, Enrique; Feliu, Juan M

    2014-07-21

    Thallium modified shape-controlled Pt nanoparticles were prepared and their electrocatalytic activity towards formic acid electrooxidation was evaluated in 0.5 M sulfuric acid. The electrochemical and in situ FTIR spectroscopic results show a remarkable improvement in the electrocatalytic activity, especially in the low potential region (around 0.1-0.2 V vs. RHE). Cubic Pt nanoparticles modified with Tl were found to be more active than the octahedral Pt ones in the entire range of Tl coverages and potential windows. In situ FTIR spectra indicate that the promotional effect produced by Tl results in the inhibition of the poisoning step leading to COads, thus improving the onset potential for the complete formic acid oxidation to CO2. Chronoamperometric experiments were also performed at 0.2 V to evaluate the stability of the electrocatalysts at constant potential. Finally, experiments with different concentrations of formic acid (0.05-1 M) were also carried out. In all cases, Tl-modified cubic Pt nanoparticles result to be the most active. All these facts reinforce the importance of controlling the surface structure of the electrocatalysts to optimize their electrocatalytic properties.

  2. Electrocatalytic oxidation of formic acid on nano/micro fibers of poly(p-anisdine) modified platinum electrode

    NASA Astrophysics Data System (ADS)

    Tammam, R. H.; Saleh, Mahmoud M.

    2014-01-01

    Poly(p-anisidine) (PPA) modified platinum (Pt) electrode shows an extraordinary electrocatalytic activity towards formic acid oxidation in acid medium compared to bare Pt electrode. The Pt/PPA is prepared by electropolymerization of the monomer on Pt electrode in salycilate aqueous solution. The PPA has a fiber-like structure with a thread size of nano- to micrometers. The cyclic voltammogram for formic acid electrooxidation on the Pt/PPA shows no peak for the indirect current and the peak current in the backward sweep is almost equal to that in the forward sweep indicating high electrocatalytic activity for FA oxidation compared to the Pt electrode which shows lower tolerance to CO poisoning. The loading level affects both the onset potential and the peak current of formic acid oxidation. Optimization of the loading level shows that a 5 cycles of polymerization (11.8 μg cm-2) is the best loading level of the PPA under the prevailed experimental conditions. The stability of the Pt/PPA towards FA oxidation confirms the higher tolerance to CO poising. SEM images and data analysis demonstrate the facilitated oxidation of FA on the Pt/PPA. Interpretation of the enhancement of FA oxidation on the Pt/PPA electrode is introduced.

  3. Revisiting formic acid decomposition on metallic powder catalysts: Exploding the HCOOH decomposition volcano curve

    NASA Astrophysics Data System (ADS)

    Tang, Yadan; Roberts, Charles A.; Perkins, Ryan T.; Wachs, Israel E.

    2016-08-01

    This study revisits the classic volcano curve for HCOOH decomposition by metal catalysts by taking a modern catalysis approach. The metal catalysts (Au, Ag, Cu, Pt, Pd, Ni, Rh, Co and Fe) were prepared by H2 reduction of the corresponding metal oxides. The number of surface active sites (Ns) was determined by formic acid chemisorption. In situ IR indicated that both monodentate and bidentate/bridged surface HCOO* were present on the metals. Heats of adsorption (ΔHads) for surface HCOO* values on metals were taken from recently reported DFT calculations. Kinetics for surface HCOO* decomposition (krds) were determined with TPD spectroscopy. Steady-state specific activity (TOF = activity/Ns) for HCOOH decomposition over the metals was calculated from steady-state activity (μmol/g-s) and Ns (μmol/g). Steady-state TOFs for HCOOH decomposition weakly correlated with surface HCOO* decomposition kinetics (krds) and ΔHads of surface HCOO* intermediates. The plot of TOF vs. ΔHads for HCOOH decomposition on metal catalysts does not reproduce the classic volcano curve, but shows that TOF depends on both ΔHads and decomposition kinetics (krds) of surface HCOO* intermediates. This is the first time that the classic catalysis study of HCOOH decomposition on metallic powder catalysts has been repeated since its original publication.

  4. Palladium-atom catalyzed formic acid decomposition and the switch of reaction mechanism with temperature.

    PubMed

    He, Nan; Li, Zhen Hua

    2016-04-21

    Formic acid decomposition (FAD) reaction has been an innovative way for hydrogen energy. Noble metal catalysts, especially palladium-containing nanoparticles, supported or unsupported, perform well in this reaction. Herein, we considered the simplest model, wherein one Pd atom is used as the FAD catalyst. With high-level theoretical calculations of CCSD(T)/CBS quality, we investigated all possible FAD pathways. The results show that FAD catalyzed by one Pd atom follows a different mechanism compared with that catalyzed by surfaces or larger clusters. At the initial stage of the reaction, FAD follows a dehydration route and is quickly poisoned by CO due to the formation of very stable PdCO. PdCO then becomes the actual catalyst for FAD at temperatures approximately below 1050 K. Beyond 1050 K, there is a switch of catalyst from PdCO to Pd atom. The results also show that dehydration is always favoured over dehydrogenation on either the Pd-atom or PdCO catalyst. On the Pd-atom catalyst, neither dehydrogenation nor dehydration follows the formate mechanism. In contrast, on the PdCO catalyst, dehydrogenation follows the formate mechanism, whereas dehydration does not. We also systematically investigated the performance of 24 density functional theory methods. We found that the performance of the double hybrid mPW2PLYP functional is the best, followed by the B3LYP, B3PW91, N12SX, M11, and B2PLYP functionals.

  5. Enhanced formic acid electro-oxidation reaction on ternary Pd-Ir-Cu/C catalyst

    NASA Astrophysics Data System (ADS)

    Chen, Jinwei; Zhang, Jie; Jiang, Yiwu; Yang, Liu; Zhong, Jing; Wang, Gang; Wang, Ruilin

    2015-12-01

    Aim to further reduce the cost of Pd-Ir for formic acid electro-oxidation (FAEO), the Cu was used to construct a ternary metallic alloy catalyst. The prepared catalysts are characterized using XRD, TGA, EDX, TEM, XPS, CO-stripping, cyclic voltammetry and chronoamperometry. It is found that the Pd18Ir1Cu6 nanoparticles with a mean size of 3.3 nm are highly dispersed on carbon support. Componential distributions on catalyst are consistent with initial contents. Electrochemical measurements show that the PdIrCu/C catalyst exhibits the highest activity for FAEO. The mass activity of Pd in Pd18Ir1Cu6/C at 0.16 V (vs. SCE) is about 1.47, 1.62 and 2.08 times as high as that of Pd18Cu6/C, Pd18Ir1/C and Pd/C, respectively. The activity enhancement of PdIrCu/C should be attributed to the weakened CO adsorption strength and the removal of adsorbed intermediates at lower potential with the addition of Cu and Ir.

  6. Sequential lignin depolymerization by combination of biocatalytic and formic acid/formate treatment steps.

    PubMed

    Gasser, Christoph A; Čvančarová, Monika; Ammann, Erik M; Schäffer, Andreas; Shahgaldian, Patrick; Corvini, Philippe F-X

    2017-03-01

    Lignin, a complex three-dimensional amorphous polymer, is considered to be a potential natural renewable resource for the production of low-molecular-weight aromatic compounds. In the present study, a novel sequential lignin treatment method consisting of a biocatalytic oxidation step followed by a formic acid-induced lignin depolymerization step was developed and optimized using response surface methodology. The biocatalytic step employed a laccase mediator system using the redox mediator 1-hydroxybenzotriazole. Laccases were immobilized on superparamagnetic nanoparticles using a sorption-assisted surface conjugation method allowing easy separation and reuse of the biocatalysts after treatment. Under optimized conditions, as much as 45 wt% of lignin could be solubilized either in aqueous solution after the first treatment or in ethyl acetate after the second (chemical) treatment. The solubilized products were found to be mainly low-molecular-weight aromatic monomers and oligomers. The process might be used for the production of low-molecular-weight soluble aromatic products that can be purified and/or upgraded applying further downstream processes.

  7. High upward fluxes of formic acid from a boreal forest canopy

    DOE PAGES

    Schobesberger, Siegfried; Lopez-Hilfiker, Felipe D.; Taipale, Ditte; ...

    2016-08-14

    Eddy covariance fluxes of formic acid, HCOOH, were measured over a boreal forest canopy in spring/summer 2014. The HCOOH fluxes were bidirectional but mostly upward during daytime, in contrast to studies elsewhere that reported mostly downward fluxes. Downward flux episodes were explained well by modeled dry deposition rates. The sum of net observed flux and modeled dry deposition yields an upward “gross flux” of HCOOH, which could not be quantitatively explained by literature estimates of direct vegetative/soil emissions nor by efficient chemical production from other volatile organic compounds, suggesting missing or greatly underestimated HCOOH sources in the boreal ecosystem. Here,more » we implemented a vegetative HCOOH source into the GEOS-Chem chemical transport model to match our derived gross flux and evaluated the updated model against airborne and spaceborne observations. Model biases in the boundary layer were substantially reduced based on this revised treatment, but biases in the free troposphere remain unexplained.« less

  8. Shape-dependent electrocatalysis: formic acid electrooxidation on cubic Pd nanoparticles.

    PubMed

    Vidal-Iglesias, Francisco J; Arán-Ais, Rosa M; Solla-Gullón, José; Garnier, Emmanuel; Herrero, Enrique; Aldaz, Antonio; Feliu, Juan M

    2012-08-07

    The electrocatalytic properties of palladium nanocubes towards the electrochemical oxidation of formic acid were studied in H(2)SO(4) and HClO(4) solutions and compared with those of spherical Pd nanoparticles. The spherical and cubic Pd nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The intrinsic electrocatalytic properties of both nanoparticles were shown to be strongly dependent on the amount of metal deposited on the gold substrate. Thus, to properly compare the activity of both systems (spheres and nanocubes), the amount of sample has to be optimized to avoid problems due to a lower diffusion flux of reactants in the internal parts of the catalyst layer resulting in a lower apparent activity. Under the optimized conditions, the activity of the spheres and nanocubes was very similar between 0.1 and 0.35 V. From this potential value, the activity of the Pd nanocubes was remarkably higher. This enhanced electrocatalytic activity was attributed to the prevalence of Pd(100) facets in agreement with previous studies with Pd single crystal electrodes. The effect of HSO(4)(-)/SO(4)(2-) desorption-adsorption was also evaluated. The activity found in HClO(4) was significantly higher than that obtained in H(2)SO(4) in the whole potential range.

  9. Microwave measurements of the tropolone-formic acid doubly hydrogen bonded dimer

    NASA Astrophysics Data System (ADS)

    Pejlovas, Aaron M.; Serrato, Agapito; Lin, Wei; Kukolich, Stephen G.

    2016-01-01

    The microwave spectrum was measured for the doubly hydrogen bonded dimer formed between tropolone and formic acid. The predicted symmetry of this dimer was C2v(M), and it was expected that the concerted proton tunneling motion would be observed. After measuring 25 a- and b-type rotational transitions, no splittings which could be associated with a concerted double proton tunneling motion were observed. The calculated barrier to the proton tunneling motion is near 15 000 cm-1, which would likely make the tunneling frequencies too small to observe in the microwave spectra. The rotational and centrifugal distortion constants determined from the measured transitions were A = 2180.7186(98) MHz, B = 470.873 90(25) MHz, C = 387.689 84(22) MHz, DJ = 0.0100(14) kHz, DJK = 0.102(28) kHz, and DK = 13.2(81) kHz. The B3LYP/aug-cc-pVTZ calculated rotational constants were within 1% of the experimentally determined values.

  10. Rotational spectra and gas phase structure of the maleimide - Formic acid doubly hydrogen bonded dimer

    NASA Astrophysics Data System (ADS)

    Pejlovas, Aaron M.; Kukolich, Stephen G.

    2016-03-01

    Rotational transitions were measured for the maleimide - formic acid doubly hydrogen bonded dimer using a Flygare-Balle type pulsed-beam Fourier transform microwave spectrometer. No splittings caused by possible concerted double proton tunneling motion were observed. Experimental rotational constants (MHz), quadrupole coupling constants (MHz), and centrifugal distortion constants (kHz) were determined for the parent and three deuterium substituted isotopologues. The values for the parent are A = 2415.0297(10), B = 784.37494(38), C = 592.44190(33), DJ = 0.0616(64), DJK = -0.118(35), DK = -1.38(15), 1.5χaa = 2.083(14), and 0.25(χbb-χcc) = 1.1565(29). The hydrogen bond lengths were determined using a nonlinear least squares structure fitting program. Rotational constants for this complex are consistent with a planar structure, with an inertial defect of Δ = -0.528 amu Å2. The B3LYP calculation yielded rotational constants within 0.1% of the experimental values.

  11. Design and identification of a high efficient formic acid cleavage site for separation of fusion protein.

    PubMed

    Zhang, Huaguang; Li, Mei; Shi, Shuangfeng; Yin, Chao; Jia, Shirong; Wang, Zhixing; Liu, Yuhui

    2015-02-01

    The release of target protein with high efficiency and low cost from expressed fusion protein is a key requirement for commercial production of target proteins. To establish such a cleavage system, we have designed four formic acid (FA) cleavage sites C1 (DPDPDP), C2 (DPPDPP), C3 (DDDDPI) and C4 (IVDPNP), which was placed in between the E and G fusion protein. Four expression vectors were individually constructed and expressed in Escherichia coli. Purified proteins were reacted with a series of FA concentrations or under different temperatures followed by SDS-PAGE gel electrophoresis to verify the degree of cleavage efficiency. Results showed that the C2 was the most efficient site compared with the other three. After optimization of cleavage conditions for E-C2-G, the cleavage efficiently could reach as high as 87.3% within 2.5 h in 37% FA at 45 °C. Comparing with previous reports, a significant reduction (26%) of FA concentration at a lower temperature in a short duration of reaction (18 times less) was achieved. We believe the cleavage site of DPPDPP identified in this study can be used in the large-scale production of valuable fusion proteins to save the cost, time and energy.

  12. Experimental and computational study of crystalline formic acid composed of the higher-energy conformer.

    PubMed

    Hakala, Mikko; Marushkevich, Kseniya; Khriachtchev, Leonid; Hämäläinen, Keijo; Räsänen, Markku

    2011-02-07

    Crystalline formic acid (FA) is studied experimentally and by first-principles simulations in order to identify a bulk solid structure composed of the higher-energy (cis) conformer. In the experiments, deuterated FA (HCOOD) was deposited in a Ne matrix and transformed to the cis conformer by vibrational excitation of the ground state (trans) form. Evaporation of the Ne host above 13 K prepared FA in a bulk solid state mainly composed of cis-FA. Infrared absorption spectroscopy at 4.3 K shows that the obtained solid differs from that composed of trans-FA molecules and that the state persists up to the annealing temperature of at least 110 K. The first-principles simulations reveal various energetically stable periodic chain structures containing cis-FA conformers. These chain structures contain either purely cis or both cis and trans forms. The vibrational frequencies of the calculated structures were compared to the experiment and a tentative assignment is given for a novel solid composed of cis-FA.

  13. Formic acid oxidation on antimony-covered platinum films with a preferential (100) orientation

    NASA Astrophysics Data System (ADS)

    Bertin, Erwan; Garbarino, Sébastien; Guay, Daniel

    2015-12-01

    The spontaneous adsorption of Sb onto nanostructured platinum electrodeposited films with a preferential (100) surface orientation, hereafter denoted Pt100 pref, was studied by means of electrochemical quartz microbalance (EQCM) and X-ray photoelectron spectroscopy. EQCM results indicated the formation of a Sb monolayer, while XPS analyses confirmed that a fraction of the as-adsorbed Sb adatoms were in a metallic state, while the others were in an oxidized state. After cycling, all of the Sb adatoms were in a metallic state. The electrocatalytic performances towards formic acid oxidation were assessed through cyclic voltammetry and chronoamperometry. On Pt100 pref, the presence of Sb markedly increased the current on the forward scan up to the potential value (typically 0.20 V) corresponding to a redox reaction occurring on the adatom. After one hour of electrolysis, the current on the Pt100 pref electrode covered with 75% Sb was ca. 15 mA cm-2geometric at 0.14 V vs SCE, which is 100 times higher than on the bare Pt100 pref electrode. The short- and long-term activities of the Pt100 pref electrode were maintained even when the electrode was disoriented through potential cycling in the Pt oxide formation and reduction region.

  14. Controlled synthesis of nanosized palladium icosahedra and their catalytic activity towards formic-acid oxidation.

    PubMed

    Lv, Tian; Wang, Yi; Choi, Sang-Il; Chi, Miaofang; Tao, Jing; Pan, Likun; Huang, Cheng Zhi; Zhu, Yimei; Xia, Younan

    2013-10-01

    Pd icosahedra with sizes controlled in the range of 5-35 nm were synthesized in high purity through a combination of polyol reduction and seed-mediated growth. The Pd icosahedra were obtained with purity >94 % and uniform sizes controlled in the range of 5-17 nm by using ethylene glycol as both the reductant and solvent. The studies indicate that the formation of Pd nanocrystals with an icosahedral shape was very sensitive to the reaction kinetics. The success of this synthesis relies on the use of HCl to manipulate the reaction kinetics and thus control the twin structure and shape of the resultant nanocrystals. The size of the Pd icosahedra could be further increased up to 35 nm by seed-mediated growth, with 17 nm Pd icosahedra serving as seeds. The multiply twinned Pd icosahedra could grow into larger sizes, and their shape and multiply twinned structure were preserved. Thanks to the presence of twin defects, the Pd icosahedra showed a catalytic current density towards formic-acid oxidation that was 1.9 and 11.6 times higher than that of single-crystal Pd octahedra, which were also fully covered by {111} facets, and commercial Pd/C, respectively. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. [Synthesis, characterization and electrocatalytic performance of Pd/CMK-3 for formic acid oxidation].

    PubMed

    Huan, Zhong-Ke; Zong, En-Min; Wei, Dan; Wan, Hai-Qin; Zheng, Shou-Rong; Xu, Zhao-Yi

    2012-10-01

    The synthesis of mesoporous carbons CMK-3 was implemented using SBA-15 samples as the hard templates and sucrose as the carbon source. Ordered mesoporous carbon CMK-3 supported palladium catalyst with a loading amount of 20% (Pd/CMK-3) was prepared by a complexing reduction method. XRD and TEM results showed that the p6mm hexagonal symmetric pore structures of CMK-3 were highly ordered and the Pd nanoparticles with the average size of 4. 2 nm and 4. 5 nm were well dispersed on CMK-3 and activated carbon (AC) surfaces respectively. Raman results revealed that CMK-3 presented higher graphitization and a higher electric conductivity than AC. The most probable pore size of CMK-3 was 4.5 nm, which is larger than that of AC (0.54 nm). The BET surface area of CMK-3 was 1 114 m2 x g(-1), which was also larger than that of AC(871 m2 x g(-1)). The mesoporous structure of CMK-3 was also observed. The Pd/CMK-3 catalyst exhibited more excellent initial electrocatalytic activity for formic acid oxidation than Pd/AC by cyclic voltammetry (CV). But the chronoamperometry (CA) demonstrated that the stability of the two catalysts were almost equal after 100 s polarization at 0.2 V (vs. SCE).

  16. Enhanced catalytic performance of Pd catalyst for formic acid electrooxidation in ionic liquid aqueous solution

    NASA Astrophysics Data System (ADS)

    Feng, Yuan-Yuan; Yin, Qian-Ying; Lu, Guo-Ping; Yang, Hai-Fang; Zhu, Xiao; Kong, De-Sheng; You, Jin-Mao

    2014-12-01

    A protic ionic liquid (IL), n-butylammonium nitrate (N4NO3), is prepared and employed as the electrolyte for formic acid electrooxidation reaction (FAOR) on Pd catalysts. The oxidation peak potential of FAOR in the IL solution shows about a 200 mV negative shift as compared with those in traditional H2SO4/HClO4 electrolytes, suggesting that FAOR can be more easily carried out on Pd catalysts in IL media. The catalytic properties of Pd toward FAOR are not only dependent on the concentration of IL, as a consequence of the varied electronic conductivity of the IL solution, but also on the high potential limit of the cyclic voltammograms. When the Pd catalyst is cycled up to 1.0 V (vs. SCE), which induces a significant oxidation of Pd, it shows ca. 4.0 times higher activity than that not subjected to the Pd oxidation (up to 0.6 V). The Pd oxides, which are more easily formed in IL solution than in traditional H2SO4/HClO4 electrolytes, may play a crucial role in increasing the catalytic activities of Pd toward FAOR. Our work would shed new light on the mechanism of FAOR and highlight the potential applications of IL as green and environment-friendly electrolytes in fuel cells and other technologies.

  17. Phase properties of carbon-supported platinum-gold nanoparticles for formic acid eletro-oxidation

    NASA Astrophysics Data System (ADS)

    Liao, Mengyin; Xiong, Jihai; Fan, Min; Shi, Jinming; Luo, Chenglong; Zhong, Chuan-Jian; Chen, Bing H.

    2015-10-01

    The design of active and robust bimetallic nanocatalysts requires the control of the nanoscale alloying, phase-segregation and the correlation between nanoscale phase-segregation and catalytic properties. To enhance the performance and durability of formic acid oxidation reaction in fuel-cell applications, we prepared a platinum-gold (PtAu) nanocatalyst with controlled morphology and composition. The catalyst is further treated by calcination under controlled temperature and atmosphere. The morphology of the bimetallic nanoparticles is determined by transmission electron microscopy. The nanoscale phase properties and surface composition are carried out by X-ray diffraction and X-ray photoelectron spectroscopy. Cyclic voltammetry measurements demonstrated that the catalytic activity is highly dependent on the nanoscale evolution of alloying and phase segregation. The mass activity of as-prepared Pt50Au50/C with 600 °C treatment temperature is about 11 times higher than that of commercial Pt/C. Stability tests showed no obvious loss of activity after 500 potential cycles. The high activity and stability are attributed to lattice contraction effect as a result of the high thermal treatment condition. Our findings demonstrate the importance of phase segregation at the nanoscale in harnessing the true electrocatalytic potential of bimetallic nanoparticles.

  18. Lattice contracted Pd-hollow nanocrystals: Synthesis, structure and electrocatalysis for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Ren, Mingjun; Chen, Ju; Li, Yuan; Zhang, Haifeng; Zou, Zhiqing; Li, Xuemei; Yang, Hui

    2014-01-01

    Hollow metal nanocrystals with tuned electronic and geometric structure are highly desirable for the efficient catalytic and/or electrocatalytic reactions. Herein, we report the synthesis of carbon-supported Pd hollow nanocrystal (Pd-hollow/C) catalyst through a galvanic replacement reaction combined with Kirkendall effect without the use of polymeric stabilizer. The Pd-hollow structure is verified by scanning transmission electron microscopy. Noticeable lattice contraction in the Pd-hollow nanocrystal has been observed by high resolution transmission electron microscopy and X-ray diffraction with a decrease in the Pd (111) lattice distance. X-ray photoelectron spectroscopy indicates that the surface Pd atoms donate more electrons to the overlap with the sub-layer atoms, suggesting a strengthened d-hybridization and a down-shift of d-band center relative to the Fermi level on the surface. Electrochemical measurements show that the Pd-hollow/C catalyst exhibits a significantly enhanced electrocatalytic activity toward formic acid oxidation. The collective effects of the hollow structure and down-shift of Pd d-band center could explain well such an enhanced catalytic activity. The present study provides new insights into the relevancy of lattice parameter, electronic structure with catalytic property, and suggests design features for excellent nanostructured catalysts.

  19. Enhanced hydrogen production from formic acid by formate hydrogen lyase-overexpressing Escherichia coli strains.

    PubMed

    Yoshida, Akihito; Nishimura, Taku; Kawaguchi, Hideo; Inui, Masayuki; Yukawa, Hideaki

    2005-11-01

    Genetic recombination of Escherichia coli in conjunction with process manipulation was employed to elevate the efficiency of hydrogen production in the resultant strain SR13 2 orders of magnitude above that of conventional methods. The formate hydrogen lyase (FHL)-overexpressing strain SR13 was constructed by combining FHL repressor (hycA) inactivation with FHL activator (fhlA) overexpression. Transcription of large-subunit formate dehydrogenase, fdhF, and large-subunit hydrogenase, hycE, in strain SR13 increased 6.5- and 7.0-fold, respectively, compared to the wild-type strain. On its own, this genetic modification effectively resulted in a 2.8-fold increase in hydrogen productivity of SR13 compared to the wild-type strain. Further enhancement of productivity was attained by using a novel method involving the induction of the FHL complex with high-cell-density filling of a reactor under anaerobic conditions. Continuous hydrogen production was achieved by maintaining the reactor concentration of the substrate (free formic acid) under 25 mM. An initial productivity of 23.6 g hydrogen h(-1) liter(-1) (300 liters h(-1) liter(-1) at 37 degrees C) was achieved using strain SR13 at a cell density of 93 g (dry weight) cells/liter. The hydrogen productivity reported in this work has great potential for practical application.

  20. Tunneling splittings in formic acid dimer: An adiabatic approximation to the Herring formula

    SciTech Connect

    Jain, Amber; Sibert, Edwin L.

    2015-02-28

    Small symmetric molecules and low-dimensional model Hamiltonians are excellent systems for benchmarking theories to compute tunneling splittings. In this work, we investigate a three dimensional model Hamiltonian coupled to a harmonic bath that describes concerted proton transfer in the formic acid dimer. The three modes include the symmetric proton stretch, the symmetric dimer rock, and the dimer stretch. These modes provide a paradigm for the symmetric and anti-symmetric coupled tunneling pathways, these being recognized in the literature as two of the more important classes of coupling. The effects of selective vibrational excitation and coupling to a bath on the tunneling splittings are presented. The splittings for highly excited states are computed using a novel method that makes an adiabatic approximation to the Herring estimate. Results, which are in excellent agreement with the exact splittings, are compared with those obtained using the Makri-Miller approach. This latter method has been shown to provide quality results for tunneling splittings including highly excited vibrational states.

  1. Rheological Properties and Electrospinnability of High-Amylose Starch in Formic Acid.

    PubMed

    Lancuški, Anica; Vasilyev, Gleb; Putaux, Jean-Luc; Zussman, Eyal

    2015-08-10

    Starch derivatives, such as starch-esters, are commonly used as alternatives to pure starch due to their enhanced mechanical properties. However, simple and efficient processing routes are still being sought out. In the present article, we report on a straightforward method for electrospinning high-amylose starch-formate nanofibers from 17 wt % aqueous formic acid (FA) dispersions. The diameter of the electrospun starch-formate fibers ranged from 80 to 300 nm. The electrospinnability window between starch gelatinization and phase separation was determined using optical microscopy and rheological studies. This window was shown to strongly depend on the water content in the FA dispersions. While pure FA rapidly gelatinized starch, yielding solutions suitable for electrospinning within a few hours at room temperature, the presence of water (80 and 90 vol % FA) significantly delayed gelatinization and dissolution, which deteriorated fiber quality. A complete destabilization of the electrospinning process was observed in 70 vol % FA dispersions. Optical micrographs showed that FA induced a disruption of starch granule with a loss of crystallinity confirmed by X-ray diffraction. As a result, starch fiber mats exhibited a higher elongation at break when compared to brittle starch films.

  2. Formic acid dehydrogenation with bioinspired iridium complexes: a kinetic isotope effect study and mechanistic insight.

    PubMed

    Wang, Wan-Hui; Xu, Shaoan; Manaka, Yuichi; Suna, Yuki; Kambayashi, Hide; Muckerman, James T; Fujita, Etsuko; Himeda, Yuichiro

    2014-07-01

    Highly efficient hydrogen generation from dehydrogenation of formic acid is achieved by using bioinspired iridium complexes that have hydroxyl groups at the ortho positions of the bipyridine or bipyrimidine ligand (i.e., OH in the second coordination sphere of the metal center). In particular, [Ir(Cp*)(TH4BPM)(H2 O)]SO4 (TH4BPM: 2,2',6,6'-tetrahydroxyl-4,4'-bipyrimidine; Cp*: pentamethylcyclopentadienyl) has a high turnover frequency of 39 500 h(-1) at 80 °C in a 1 M aqueous solution of HCO2 H/HCO2 Na and produces hydrogen and carbon dioxide without carbon monoxide contamination. The deuterium kinetic isotope effect study clearly indicates a different rate-determining step for complexes with hydroxyl groups at different positions of the ligands. The rate-limiting step is β-hydrogen elimination from the iridium-formate intermediate for complexes with hydroxyl groups at ortho positions, owing to a proton relay (i.e., pendent-base effect), which lowers the energy barrier of hydrogen generation. In contrast, the reaction of iridium hydride with a proton to liberate hydrogen is demonstrated to be the rate-determining step for complexes that do not have hydroxyl groups at the ortho positions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Formic Acid Dehydrogenation on Au-Based Catalysts at Near-Ambient Temperatures

    SciTech Connect

    Ojeda, Manuel; Iglesia, Enrique

    2008-11-24

    Formic acid (HCOOH) is a convenient hydrogen carrier in fuel cells designed for portable use. Recent studies have shown that HCOOH decomposition is catalyzed with Ru-based complexes in the aqueous phase at near-ambient temperatures. HCOOH decomposition reactions are used frequently to probe the effects of alloying and cluster size and of geometric and electronic factors in catalysis. These studies have concluded that Pt is the most active metal for HCOOH decomposition, at least as large crystallites and extended surfaces. The identity and oxidation state of surface metal atoms influence the relative rates of dehydrogenation (HCOOH {yields} H{sub 2} + CO{sub 2}) and dehydration (HCOOH {yields} H{sub 2}O + CO) routes, a selectivity requirement for the synthesis of CO-free H{sub 2} streams for low-temperature fuel cells. Group Ib and Group VIII noble metals catalyze dehydrogenation selectively, while base metals and metal oxides catalyze both routes, either directly or indirectly via subsequent water-gas shift (WGS) reactions.

  4. Formic Acid Decomposition on Au catalysts: DFT, Microkinetic Modeling, and Reaction Kinetics Experiments

    SciTech Connect

    Singh, Suyash; Li, Sha; Carrasquillo-Flores, Ronald; Alba-Rubio, Ana C.; Dumesic, James A.; Mavrikakis, Manos

    2014-04-01

    A combined theoretical and experimental approach is presented that uses a comprehensive mean-field microkinetic model, reaction kinetics experiments, and scanning transmission electron microscopy imaging to unravel the reaction mechanism and provide insights into the nature of active sites for formic acid (HCOOH) decomposition on Au/SiC catalysts. All input parameters for the microkinetic model are derived from periodic, self-consistent, generalized gradient approximation (GGA-PW91) density functional theory calculations on the Au(111), Au(100), and Au(211) surfaces and are subsequently adjusted to describe the experimental HCOOH decomposition rate and selectivity data. It is shown that the HCOOH decomposition follows the formate (HCOO) mediated path, with 100% selectivity toward the dehydrogenation products (CO21H2) under all reaction conditions. An analysis of the kinetic parameters suggests that an Au surface in which the coordination number of surface Au atoms is 4 may provide a better model for the active site of HCOOH decomposition on these specific supported Au catalysts.

  5. Enhancement of biomass conversion in catalytic fast pyrolysis by microwave-assisted formic acid pretreatment.

    PubMed

    Feng, Yu; Li, Guangyu; Li, Xiangyu; Zhu, Ning; Xiao, Bo; Li, Jian; Wang, Yujue

    2016-08-01

    This study investigated microwave-assisted formic acid (MW-FA) pretreatment as a possible way to improve aromatic production from catalytic fast pyrolysis (CFP) of lignocellulosic biomass. Results showed that short duration of MW-FA pretreatment (5-10min) could effectively disrupt the recalcitrant structure of beech wood and selectively remove its hemicellulose and lignin components. This increased the accessibility of cellulose component of biomass to subsequent thermal conversion in CFP. Consequently, the MW-FA pretreated beech wood produced 14.0-28.3% higher yields (26.4-29.8C%) for valuable aromatic products in CFP than the untreated control (23.2C%). In addition, the yields of undesired solid residue (char/coke) decreased from 33.1C% for the untreated control to 28.6-29.8C% for the MW-FA pretreated samples. These results demonstrate that MW-FA pretreatment can provide an effective way to improve the product distribution from CFP of lignocellulose.

  6. Selective hydrogen production from formic acid decomposition on Pd-Au bimetallic surfaces.

    PubMed

    Yu, Wen-Yueh; Mullen, Gregory M; Flaherty, David W; Mullins, C Buddie

    2014-08-06

    Pd-Au catalysts have shown exceptional performance for selective hydrogen production via HCOOH decomposition, a promising alternative to solve issues associated with hydrogen storage and distribution. In this study, we utilized temperature-programmed desorption (TPD) and reactive molecular beam scattering (RMBS) in an attempt to unravel the factors governing the catalytic properties of Pd-Au bimetallic surfaces for HCOOH decomposition. Our results show that Pd atoms at the Pd-Au surface are responsible for activating HCOOH molecules; however, the selectivity of the reaction is dictated by the identity of the surface metal atoms adjacent to the Pd atoms. Pd atoms that reside at Pd-Au interface sites tend to favor dehydrogenation of HCOOH, whereas Pd atoms in Pd(111)-like sites, which lack neighboring Au atoms, favor dehydration of HCOOH. These observations suggest that the reactivity and selectivity of HCOOH decomposition on Pd-Au catalysts can be tailored by controlling the arrangement of surface Pd and Au atoms. The findings in this study may prove informative for rational design of Pd-Au catalysts for associated reactions including selective HCOOH decomposition for hydrogen production and electro-oxidation of HCOOH in the direct formic acid fuel cell.

  7. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    SciTech Connect

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/C and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.

  8. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    DOE PAGES

    Zhu, Jing; Zheng, Xin; Wang, Jie; ...

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/Cmore » and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.« less

  9. Microwave measurements of the tropolone–formic acid doubly hydrogen bonded dimer

    SciTech Connect

    Pejlovas, Aaron M.; Kukolich, Stephen G.; Serrato, Agapito; Lin, Wei

    2016-01-28

    The microwave spectrum was measured for the doubly hydrogen bonded dimer formed between tropolone and formic acid. The predicted symmetry of this dimer was C{sub 2v}(M), and it was expected that the concerted proton tunneling motion would be observed. After measuring 25 a- and b-type rotational transitions, no splittings which could be associated with a concerted double proton tunneling motion were observed. The calculated barrier to the proton tunneling motion is near 15 000 cm{sup −1}, which would likely make the tunneling frequencies too small to observe in the microwave spectra. The rotational and centrifugal distortion constants determined from the measured transitions were A = 2180.7186(98) MHz, B = 470.873 90(25) MHz, C = 387.689 84(22) MHz, D{sub J} = 0.0100(14) kHz, D{sub JK} = 0.102(28) kHz, and D{sub K} = 13.2(81) kHz. The B3LYP/aug-cc-pVTZ calculated rotational constants were within 1% of the experimentally determined values.

  10. Reducing Pt use in the catalysts for formic acid electrooxidation via nanoengineered surface structure

    NASA Astrophysics Data System (ADS)

    Liao, Mengyin; Wang, Yulu; Chen, Guoqin; Zhou, Hua; Li, Yunhua; Zhong, Chuan-Jian; Chen, Bing H.

    2014-07-01

    The design of active and durable catalysts for formic acid (FA) electrooxidation requires controlling the amount of three neighboring platinum atoms in the surface of Pt-based catalysts. Such requirement is studied by preparing Pt decorated Pd/C (donated as Pt-Pd/C) with various Pt:Pd molar ratios via galvanic displacement making the amount of three neighboring Pt atoms in the surface of Pt-Pd/C tunable. The decorated nanostructures are confirmed by XPS, HS-LEIS, cyclic voltammetry and chronoamperometric measurements, demonstrating that Pt-Pd/C (the optimal molar ratio, Pt:Pd = 1:250) exhibits superior activity and durability than Pd/C and commercial Pt/C (J-M, 20%) catalysts for FA electrooxidation. The mass activity of Pt-Pd/C (Pt:Pd = 1:250) (3.91 A mg-1) is about 98 and 6 times higher than that of commercial Pt/C (0.04 A mg-1) and Pd/C (0.63 A mg-1) at a given potential of 0.1 V vs SCE, respectively. The controlled synthesis of Pt-Pd/C lead to the formation of largely discontinuous Pd and Pt sites and inhibition of CO formation, exhibiting unprecedented electrocatalytic performance toward FA electrooxidation while the cost of the catalyst almost the same as Pd/C. These findings have profound implications to the design and nanoengineering of decorated surfaces of catalysts for FA electrooxidation.

  11. Insights into the spontaneity of hydrogen bond formation between formic acid and phthalimide derivatives.

    PubMed

    Júnior, Rogério V A; Moura, Gustavo L C; Lima, Nathalia B D

    2016-11-01

    We evaluated a group of phthalimide derivatives, which comprise a convenient test set for the study of the multiple factors involved in the energetics of hydrogen bond formation. Accordingly, we carried out quantum chemical calculations on the hydrogen bonded complexes formed between a sample of phthalimide derivatives with formic acid with the intent of identifying the most important electronic and structural factors related to how their strength and spontaneity vary across the series. The geometries of all species considered were fully optimized at DFT B3LYP/6-31++G(d,p), RM1, RM1-DH2, and RM1-D3H4 level, followed by frequency calculations to determine their Gibbs free energies of hydrogen bond formation using Gaussian 2009 and MOPAC 2012. Our results indicate that the phthalimide derivatives that form hydrogen bond complexes most favorably, have in their structures only one C=O group and at least one NH group. On the other hand, the phthalimide derivatives predicted to form hydrogen bonds least favorably, possess in their structures two carbonyl groups, C=O, and no NH group. The ability to donate electrons and simultaneously receive one acidic hydrogen is the most important property related to the spontaneity of hydrogen bond formation. We further chose two cyclic compounds, phthalimide and isoindolin-1-one, in which to study the main changes in molecular, structural and spectroscopic properties as related to the formation of hydrogen bonds. Thus, the greatest ability of the isoindolin-1-one compound in forming hydrogen bonds is evidenced by the larger effect on the structural, vibrational, and chemical shifts properties associated with the O-H group. In summary, the electron-donating ability of the hydrogen bond acceptor emerged as the most important property differentiating the spontaneity of hydrogen bond formation in this group of complexes.

  12. Experimental and Kinetic Study on Lignin Depolymerization in Water/Formic Acid System.

    PubMed

    Wang, Qi; Guan, Sipian; Shen, Dekui

    2017-10-01

    Microwave-assisted depolymerization of black-liquor lignin in formic acid was studied, concentrating on the yield of liquid fractions as bio-oil 1 (mainly aromatic monomers) and bio-oil 2 (mainly aromatic oligomers) and the distribution of the specific compositions. Bio-oil 1 (9.69%) and bio-oil 2 (54.39%) achieved their maximum yields under 160 °C with the reaction time of 30 min. The chemical compositions of bio-oil 1 and bio-oil 2 were respectively identified by means of Gas Chromatography-Mass Spectrometer (GC-MS) and Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Ethanone, 1-(4-hydroxy-3-methoxyphenyl) and Ethanone, 1-(4-hydrox-3,5-dimethoxyphenyl) were evidenced to be the two prominent compounds in bio-oil 1. Production of aromatic oligomers with the molecular weight of 328, 342, 358, 378, 394, 424 and 454 identified by MALDI-TOF MS was substantially tuned with the reaction temperature. A two-separate-stage kinetic model was proposed to describe the acidic solvolysis of lignin assisted by microwave heating, where the first stage is dominated by the depolyerization of lignin to monomers and oligomers with the activation energy of 40.27 kJ·mol(-1), and the second stage with the activation energy of 49.18 kJ·mol(-1) is mainly ascribed to the repolymerization of first-stage produced compounds.

  13. Hollow Ag@Pd core-shell nanotubes as highly active catalysts for the electro-oxidation of formic acid.

    PubMed

    Jiang, Yuanyuan; Lu, Yizhong; Han, Dongxue; Zhang, Qixian; Niu, Li

    2012-03-16

    Ag nanowires are prepared as templates by a polyol reduction process. Then Ag nanotubes coated with a thin layer of Pd are synthesized through sequential reduction accompanied with the galvanic displacement reaction. The products show a hollow core-shell nanotubular structure, as demonstrated by detailed characterizations. The Ag@Pd can significantly improve the electrocatalytic activity towards the electro-oxidation of formic acid and enhance the stability of the Pd component. It is proposed that the enhanced electrochemically active surface area and modulated electron structure of Pd by Ag are responsible for the improvement of electrocatalytic activity and durability. The results obtained in this work are different from those previous reports, in which alloy walls with hollow interiors are usually formed. This work provides a new and simple method for synthesizing novel bimetallic core-shell structure with a hollow interior, which can be applied as high-performance catalysts for the electro-oxidation of formic acid.

  14. Monodisperse gold-palladium alloy nanoparticles and their composition-controlled catalysis in formic acid dehydrogenation under mild conditions

    NASA Astrophysics Data System (ADS)

    Metin, Önder; Sun, Xiaolian; Sun, Shouheng

    2013-01-01

    Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(iii) hydrate and palladium(ii) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h-1) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives.Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(iii) hydrate and palladium(ii) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h-1) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives. Electronic supplementary information (ESI) available: Experimental procedures (NP synthesis, characterization and catalytic FA dehydrogenation) and figures (Fig. S1-S5). See DOI: 10.1039/c2nr33637e

  15. Hydrogenation of biofuels with formic acid over a palladium-based ternary catalyst with two types of active sites.

    PubMed

    Wang, Liang; Zhang, Bingsen; Meng, Xiangju; Su, Dang Sheng; Xiao, Feng-Shou

    2014-06-01

    A composite catalyst including palladium nanoparticles on titania (TiO2) and on nitrogen-modified porous carbon (Pd/TiO2@N-C) is synthesized from palladium salts, tetrabutyl titanate, and chitosan. N2 sorption isotherms show that the catalyst has a high BET surface area (229 m(2)  g(-1)) and large porosity. XPS and TEM characterization of the catalyst shows that palladium species with different chemical states are well dispersed across the TiO2 and nitrogen-modified porous carbon, respectively. The Pd/TiO2@N-C catalyst is very active and shows excellent stability towards hydrogenation of vanillin to 2-methoxy-4-methylphenol using formic acid as hydrogen source. This activity can be attributed to a synergistic effect between the Pd/TiO2 (a catalyst for dehydrogenation of formic acid) and Pd/N-C (a catalyst for hydrogenation of vanillin) sites.

  16. Selective oxidation of lignocellulosic biomass to formic acid and high-grade cellulose using tailor-made polyoxometalate catalysts.

    PubMed

    Albert, Jakob

    2017-06-27

    The main goal of this project was to identify and optimize tailor-made polyoxometalate catalysts for a fractionated oxidation of lignocellulosic biomass (i.e. wood and residues from sugar or paper industries) to produce formic acid (FA) and high-grade cellulose for further processing e.g. in white biotechnology to provide bio-ethanol. Homogeneous vanadium precursors like sodium metavanadate and vanadyl sulfate as well as Keggin-type polyoxometalates (POMs) and more exotic structures like Anderson-, Wells-Dawson- and Lindqvist-type POMs were screened for the desired catalytic performance. The most promising behaviour was found using the Lindqvist-type POM K5V3W3O19, showing for the first time in the literature a selective oxidation of only hemicellulose and lignin to formic acid, while the cellulose fraction was untrapped. However, this can only be a first step towards the project goal as low product yields were obtained.

  17. High-surface step density on dendritic pd leads to exceptional catalytic activity for formic acid oxidation.

    PubMed

    Patra, S; Viswanath, B; Barai, K; Ravishankar, N; Munichandraiah, N

    2010-11-01

    Dendritic Pd with corrugated surfaces, obtained by a novel AC technique, exhibits an exceptionally high catalytic activity for the oxidation of formic acid because of the presence of a high density of surface steps. The formation of twinned dendrites leads to a predominance of exposed 111 facets with a high density of surface steps as evident from high resolution electron microscopy investigations. These surface sites provide active sites for the adsorption of the formic acid molecules, thereby enhancing the reaction rate. Control experiments by varying the time of deposition reveal the formation of partially grown dendrites at shorter times indicating that the dendrites were formed by growth rather than particle attachment. Our deposition method opens up interesting possibilities to produce anisotropic nanostructures with corrugated surfaces by exploiting the perturbations involved in the growth process.

  18. One-pot synthesis of graphene-supported monodisperse Pd nanoparticles as catalyst for formic acid electro-oxidation.

    PubMed

    Yang, Sudong; Dong, Jing; Yao, Zhaohui; Shen, Chengmin; Shi, Xuezhao; Tian, Yuan; Lin, Shaoxiong; Zhang, Xiaogang

    2014-03-28

    To synthesize monodisperse palladium nanoparticles dispersed on reduced graphene oxide (RGO) sheets, we have developed an easy and scalable solvothermal reduction method from an organic solution system. The RGO-supported palladium nanoparticles with a diameter of 3.8 nm are synthesized in N-methyl-2-pyrrolidone (NMP) and in the presence of oleylamine and trioctylphosphine, which facilitates simultaneous reduction of graphene oxide and formation of Pd nanocrystals. So-produced Pd/RGO was tested for potential use as electrocatalyst for the electro-oxidation of formic acid. Pd/RGO catalyzes formic acid oxidation very well compared to Pd/Vulcan XC-72 catalyst. This synthesis method is a new way to prepare excellent electrocatalysts, which is of great significance in energy-related catalysis.

  19. Porous AgPt@Pt Nanooctahedra as an Efficient Catalyst toward Formic Acid Oxidation with Predominant Dehydrogenation Pathway.

    PubMed

    Jiang, Xian; Yan, Xiaoxiao; Ren, Wangyu; Jia, Yufeng; Chen, Jianian; Sun, Dongmei; Xu, Lin; Tang, Yawen

    2016-11-16

    For direct formic acid fuel cells (DFAFCs), the dehydrogenation pathway is a desired reaction pathway, to boost the overall cell efficiency. Elaborate composition tuning and nanostructure engineering provide two promising strategies to design efficient electrocatalysts for DFAFCs. Herein, we present a facile synthesis of porous AgPt bimetallic nanooctahedra with enriched Pt surface (denoted as AgPt@Pt nanooctahedra) by a selective etching strategy. The smart integration of geometric and electronic effect confers a substantial enhancement of desired dehydrogenation pathway as well as electro-oxidation activity for the formic acid oxidation reaction (FAOR). We anticipate that the obtained nanocatalyst may hold great promises in fuel cell devices, and furthermore, the facile synthetic strategy demonstrated here can be extendable for the fabrication of other multicomponent nanoalloys with desirable morphologies and enhanced electrocatalytic performances.

  20. Hollow Ag@Pd core-shell nanotubes as highly active catalysts for the electro-oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Jiang, Yuanyuan; Lu, Yizhong; Han, Dongxue; Zhang, Qixian; Niu, Li

    2012-03-01

    Ag nanowires are prepared as templates by a polyol reduction process. Then Ag nanotubes coated with a thin layer of Pd are synthesized through sequential reduction accompanied with the galvanic displacement reaction. The products show a hollow core-shell nanotubular structure, as demonstrated by detailed characterizations. The Ag@Pd can significantly improve the electrocatalytic activity towards the electro-oxidation of formic acid and enhance the stability of the Pd component. It is proposed that the enhanced electrochemically active surface area and modulated electron structure of Pd by Ag are responsible for the improvement of electrocatalytic activity and durability. The results obtained in this work are different from those previous reports, in which alloy walls with hollow interiors are usually formed. This work provides a new and simple method for synthesizing novel bimetallic core-shell structure with a hollow interior, which can be applied as high-performance catalysts for the electro-oxidation of formic acid.

  1. Development of Pd and Pd-Co catalysts supported on multi-walled carbon nanotubes for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Morales-Acosta, D.; Ledesma-Garcia, J.; Godinez, Luis A.; Rodríguez, H. G.; Álvarez-Contreras, L.; Arriaga, L. G.

    Pd-Co and Pd catalysts were prepared by the impregnation synthesis method at low temperature on multi-walled carbon nanotubes (MWCNTs). The nanotubes were synthesized by spray pyrolysis technique. Both catalysts were obtained with high homogeneous distribution and particle size around 4 nm. The morphology, composition and electrocatalytic properties were investigated by transmission electron microscopy, scanning electron microscopy-energy dispersive X-ray analysis, X-ray diffraction and electrochemical measurements, respectively. The electrocatalytic activity of Pd and PdCo/MWCNTs catalysts was investigated in terms of formic acid electrooxidation at low concentration in H 2SO 4 aqueous solution. The results obtained from voltamperometric studies showed that the current density achieved with the PdCo/MWCNTs catalyst is 3 times higher than that reached with the Pd/MWCNTs catalyst. The onset potential for formic acid electrooxidation on PdCo/MWCNTs electrocatalyst showed a negative shift ca. 50 mV compared with Pd/MWCNTs.

  2. One-Pot Synthesis of Graphene-Supported Monodisperse Pd Nanoparticles as Catalyst for Formic Acid Electro-oxidation

    NASA Astrophysics Data System (ADS)

    Yang, Sudong; Dong, Jing; Yao, Zhaohui; Shen, Chengmin; Shi, Xuezhao; Tian, Yuan; Lin, Shaoxiong; Zhang, Xiaogang

    2014-03-01

    To synthesize monodisperse palladium nanoparticles dispersed on reduced graphene oxide (RGO) sheets, we have developed an easy and scalable solvothermal reduction method from an organic solution system. The RGO-supported palladium nanoparticles with a diameter of 3.8 nm are synthesized in N-methyl-2-pyrrolidone (NMP) and in the presence of oleylamine and trioctylphosphine, which facilitates simultaneous reduction of graphene oxide and formation of Pd nanocrystals. So-produced Pd/RGO was tested for potential use as electrocatalyst for the electro-oxidation of formic acid. Pd/RGO catalyzes formic acid oxidation very well compared to Pd/Vulcan XC-72 catalyst. This synthesis method is a new way to prepare excellent electrocatalysts, which is of great significance in energy-related catalysis.

  3. One-Pot Synthesis of Graphene-Supported Monodisperse Pd Nanoparticles as Catalyst for Formic Acid Electro-oxidation

    PubMed Central

    Yang, Sudong; Dong, Jing; Yao, Zhaohui; Shen, Chengmin; Shi, Xuezhao; Tian, Yuan; Lin, Shaoxiong; Zhang, Xiaogang

    2014-01-01

    To synthesize monodisperse palladium nanoparticles dispersed on reduced graphene oxide (RGO) sheets, we have developed an easy and scalable solvothermal reduction method from an organic solution system. The RGO-supported palladium nanoparticles with a diameter of 3.8 nm are synthesized in N-methyl-2-pyrrolidone (NMP) and in the presence of oleylamine and trioctylphosphine, which facilitates simultaneous reduction of graphene oxide and formation of Pd nanocrystals. So-produced Pd/RGO was tested for potential use as electrocatalyst for the electro-oxidation of formic acid. Pd/RGO catalyzes formic acid oxidation very well compared to Pd/Vulcan XC-72 catalyst. This synthesis method is a new way to prepare excellent electrocatalysts, which is of great significance in energy-related catalysis. PMID:24675779

  4. Optimization of furfural production from D-xylose with formic acid as catalyst in a reactive extraction system.

    PubMed

    Yang, Wandian; Li, Pingli; Bo, Dechen; Chang, Heying; Wang, Xiaowei; Zhu, Tao

    2013-04-01

    Furfural is one of the most promising platform chemicals derived from biomass. In this study, response surface methodology (RSM) was utilized to determine four important parameters including reaction temperature (170-210°C), formic acid concentration (5-25 g/L), o-nitrotoluene volume percentage (20-80 vt.%), and residence time (40-200 min). The maximum furfural yield of 74% and selectivity of 86% were achieved at 190°C for 20 g/L formic acid concentration and 75 vt.% o-nitrotoluene by 75 min. The high boiling solvent, o-nitrotoluene, was recommended as extraction solvent in a reactive extraction system to obtain high furfural yield and reduce furfural-solvent separation costs. Although the addition of halides to the xylose solutions enhanced the furfural yield and selectivity, the concentration of halides was not an important factor on the furfural yield and selectivity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Theoretical interpretation of the infrared lineshapes of the H- and D-bonds in liquid formic acid

    NASA Astrophysics Data System (ADS)

    Fathi, Sonia; Blaise, Paul; Ceausu-Velcescu, Adina; Nasr, Salah

    2017-07-01

    A full quantum theoretical approach has been used to study the νOsbnd H experimental IR line shapes of liquid formic acid. For this purpose, a previous model [Benmalti et al., 2009], which accounts for the proportion of cyclic dimers, has been successfully adapted. The present model thus incorporates the strong anharmonic coupling between the high frequency mode and the H-bond bridge, the Davydov coupling between the excited states of the two moieties, multiple Fermi resonances between the νOsbnd H (Bu) mode and combinations of some bending modes, together with the quantum direct and indirect dampings. This model reproduces satisfactorily the main features of the experimental lineshapes of liquid hydrogenated and deuterated formic acid, by using a minimum set of independent parameters.

  6. An efficient room temperature core-shell AgPd@MOF catalyst for hydrogen production from formic acid

    NASA Astrophysics Data System (ADS)

    Ke, Fei; Wang, Luhuan; Zhu, Junfa

    2015-04-01

    Novel core-shell AgPd@MIL-100(Fe) NPs were fabricated by a facile one-pot method. Significantly, the as-prepared core-shell NPs exhibit much higher catalytic activity than the pure AgPd NPs toward hydrogen production from formic acid without using any additive at room temperature.Novel core-shell AgPd@MIL-100(Fe) NPs were fabricated by a facile one-pot method. Significantly, the as-prepared core-shell NPs exhibit much higher catalytic activity than the pure AgPd NPs toward hydrogen production from formic acid without using any additive at room temperature. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07582j

  7. Lack of formic acid production in rat hepatocytes and human renal proximal tubule cells exposed to chloral hydrate or trichloroacetic acid.

    PubMed

    Lock, Edward A; Reed, Celia J; McMillan, Joellyn M; Oatis, John E; Schnellmann, Rick G

    2007-02-12

    The industrial solvent trichloroethylene (TCE) and its major metabolites have been shown to cause formic aciduria in male rats. We have examined whether chloral hydrate (CH) and trichloroacetic acid (TCA), known metabolites of TCE, produce an increase in formic acid in vitro in cultures of rat hepatocytes or human renal proximal tubule cells (HRPTC). The metabolism and cytotoxicity of CH was also examined to establish that the cells were metabolically active and not compromised by toxicity. Rat hepatocytes and HRPTC were cultured in serum-free medium and then treated with 0.3-3mM CH for 3 days or 0.03-3mM CH for 10 days, respectively and formic acid production, metabolism to trichloroethanol (TCE-OH) and TCA and cytotoxicity determined. No increase in formic acid production in rat hepatocytes or HRPTC exposed to CH was observed over and above that due to chemical degradation, neither was formic acid production observed in rat hepatocytes exposed to TCA. HRPTC metabolized CH to TCE-OH and TCA with a 12-fold greater capacity to form TCE-OH versus TCA. Rat hepatocytes exhibited a 1.6-fold and three-fold greater capacity than HRPTC to form TCE-OH and TCA, respectively. CH and TCA were not cytotoxic to rat hepatocytes at concentrations up to 3mM/day for 3 days. With HRPTC, one sample showed no cytotoxicity to CH at concentrations up to 3mM/day for 10 days, while in another cytotoxicity was seen at 1mM/day for 3 days. In summary, increased formic acid production was not observed in rat hepatocytes or HRPTC exposed to TCE metabolites, suggesting that the in vivo response cannot be modelled in vitro. CH was toxic to HRPTC at millimolar concentrations/day over 10 days, while glutathione derived metabolites of TCE were toxic at micromolar concentrations/day over 10 days [Lock, E.A., Reed, C.J., 2006. Trichloroethylene: mechanisms of renal toxicity and renal cancer and relevance to risk assessment. Toxicol. Sci. 19, 313-331] supporting the view that glutathione derived

  8. A highly active Pd-P nanoparticle electrocatalyst for enhanced formic acid oxidation synthesized via stepwise electroless deposition.

    PubMed

    Poon, Kee Chun; Khezri, Bahareh; Li, Yao; Webster, Richard D; Su, Haibin; Sato, Hirotaka

    2016-02-28

    A highly active Pd-P nanoparticle electrocatalyst for formic acid oxidation was synthesized using NaH2PO2 as the reducing agent. The Pd-P nanoparticles were amorphous and exhibited higher specific and mass activity values compared to commercial Pd/C electrocatalyts and reported literature values. Furthermore, the Pd-P nanoparticles were found to be more durable than Pd/C electrocatalyts.

  9. Formate adsorption on Pt nanoparticles during formic acid electro-oxidation: insights from in situ infrared spectroscopy.

    PubMed

    McPherson, Ian J; Ash, Philip A; Jacobs, Robert M J; Vincent, Kylie A

    2016-10-18

    Adsorbed formate is observed on a supported Pt nanoparticle for the first time during formic acid electro-oxidation. Bands assigned to OCO stretching and CH bending reveal some OCO but little CH bond weakening on adsorption compared to the free anion. The formate potential dependence is similar to polycrystalline electrodes while adsorbed CO persists up to +1.2 V, 0.5 V higher than on polycrystalline Pt.

  10. Mixed-phase PdRu bimetallic structures with high activity and stability for formic acid electrooxidation.

    PubMed

    Wu, Dongshuang; Zheng, Zhaoliang; Gao, Shuiying; Cao, Minna; Cao, Rong

    2012-06-14

    Aiming at investigating the effect of structure on electrocatalytic properties, Pd(50)Ru(50) nanoparticles (NPs) with three different structures were carefully designed in a one-pot polyol process for application in formic acid electrooxidation. The three structures are: (1) single-phase PdRu nanodendrites (denoted as PR-1), (2) a mixed-phase mixture of PdRu nanodendrites and monometallic Ru NPs (denoted as PR-2), and (3) a mixed-phase mixture of monometallic Pd and Ru NPs (denoted as PR-3). From PR-1 to PR-3, the structure was varied from single-phase to mixed-phase. The relative position of Ru was altered from completely Pd-connected (PR-1), to a mixture of Pd-connected and monometallic (PR-2), and completely monometallic (PR-3). All PdRu NPs outperform the commercial Pd/C. PR-2 exhibits the highest peak current density, but its stability is slightly lower than that of PR-3. When both the current density and the durability are taken into consideration, PR-2 is the best choice of catalyst for formic acid oxidation. It indicates that both the Pd-connected Ru NPs and monometallic Ru NPs in the mixed-phase PR-2 are essential to improve the electrocatalytic properties. Our study also illustrates that the electrochemical active surface area (ECSA) and hydrogen storage capacity of the as-prepared PdRu NPs are greatly enhanced after several hundred scans in formic acid, indicating the possibility for highly restorable catalysts in direct formic acid fuel cells.

  11. Reversible Hydrogenation of Carbon Dioxide to Formic Acid and Methanol: Lewis Acid Enhancement of Base Metal Catalysts.

    PubMed

    Bernskoetter, Wesley H; Hazari, Nilay

    2017-03-17

    New and sustainable energy vectors are required as a consequence of the environmental issues associated with the continued use of fossil fuels. H2 is a potential clean energy source, but as a result of problems associated with its storage and transport as a gas, chemical H2 storage (CHS), which involves the dehydrogenation of small molecules, is an attractive alternative. In principle, formic acid (FA, 4.4 wt % H2) and methanol (MeOH, 12.6 wt % H2) can be obtained renewably and are excellent prospective liquid CHS materials. In addition, MeOH has considerable potential both as a direct replacement for gasoline and as a fuel cell input. The current commercial syntheses of FA and MeOH, however, use nonrenewable feedstocks and will not facilitate the use of these molecules for CHS. An appealing option for the sustainable synthesis of both FA and MeOH, which could be implemented on a large scale, is the direct metal catalyzed hydrogenation of CO2. Furthermore, given that CO2 is a readily available, nontoxic and inexpensive source of carbon, it is expected that there will be economic and environmental benefits from using CO2 as a feedstock. One strategy to facilitate both the dehydrogenation of FA and MeOH and the hydrogenation of CO2 and H2 to FA and MeOH is to utilize a homogeneous transition metal catalyst. In particular, the development of catalysts based on first row transition metals, which are cheaper, and more abundant than their precious metal counterparts, is desirable. In this Account, we describe recent advances in the development of iron and cobalt systems for the hydrogenation of CO2 to FA and MeOH and the dehydrogenation of FA and MeOH and provide a brief comparison between precious metal and base metal systems. We highlight the different ligands that have been used to stabilize first row transition metal catalysts and discuss the use of additives to promote catalytic activity. In particular, the Account focuses on the crucial role that alkali metal Lewis

  12. Ligand-induced substrate steering and reshaping of [Ag2(H)]+ scaffold for selective CO2 extrusion from formic acid

    PubMed Central

    Zavras, Athanasios; Khairallah, George N.; Krstić, Marjan; Girod, Marion; Daly, Steven; Antoine, Rodolphe; Maitre, Philippe; Mulder, Roger J.; Alexander, Stefanie-Ann; Bonačić-Koutecký, Vlasta; Dugourd, Philippe; O'Hair, Richard A. J.

    2016-01-01

    Metalloenzymes preorganize the reaction environment to steer substrate(s) along the required reaction coordinate. Here, we show that phosphine ligands selectively facilitate protonation of binuclear silver hydride cations, [LAg2(H)]+ by optimizing the geometry of the active site. This is a key step in the selective, catalysed extrusion of carbon dioxide from formic acid, HO2CH, with important applications (for example, hydrogen storage). Gas-phase ion-molecule reactions, collision-induced dissociation (CID), infrared and ultraviolet action spectroscopy and computational chemistry link structure to reactivity and mechanism. [Ag2(H)]+ and [Ph3PAg2(H)]+ react with formic acid yielding Lewis adducts, while [(Ph3P)2Ag2(H)]+ is unreactive. Using bis(diphenylphosphino)methane (dppm) reshapes the geometry of the binuclear Ag2(H)+ scaffold, triggering reactivity towards formic acid, to produce [dppmAg2(O2CH)]+ and H2. Decarboxylation of [dppmAg2(O2CH)]+ via CID regenerates [dppmAg2(H)]+. These gas-phase insights inspired variable temperature NMR studies that show CO2 and H2 production at 70 °C from solutions containing dppm, AgBF4, NaO2CH and HO2CH. PMID:27265868

  13. Understanding the enhanced catalytic activity of Cu1@Pd3(111) in formic acid dissociation, a theoretical perspective

    NASA Astrophysics Data System (ADS)

    He, Feng; Li, Kai; Xie, Guangyou; Wang, Ying; Jiao, Menggai; Tang, Hao; Wu, Zhijian

    2016-06-01

    The bimetallic Cu1@Pd3(111) catalyst has been synthesized recently and exhibits better catalytic activity and durability compared with pure Pd(111) as anode catalyst in direct formic acid fuel cells (DFAFCs). In this work, we studied the reaction mechanism of formic acid dissociation on both Pd(111) and Cu1@Pd3(111) by using the density functional method. Our calculations showed that the surface adsorption of the poisoning species CO on Cu1@Pd3(111) is weakened mainly by the strain effect rather than the Cusbnd Pd ligand effect. The Cu1@Pd3(111) can effectively promote the catalytic activity for formic acid dissociation by decreasing the barrier of CO2 formation from the preferential trans-COOH intermediate and increasing the barrier of CO formation from the reduction of CO2. We found that the H atom accumulation, electron accumulation and low electrode potential could accelerate the catalyst deactivation due to the contamination of the poisoning species CO. Furthermore, under low anode potential, the Cu1@Pd3(111) has better durability than pure Pd(111), which can be attributed to the unfavorable CO formation and the favorable CO desorption.

  14. Enhancing the activity and tuning the mechanism of formic acid oxidation at tetrahexahedral Pt nanocrystals by Au decoration.

    PubMed

    Liu, Hai-Xia; Tian, Na; Brandon, Michael P; Pei, Jun; Huangfu, Zhi-Chao; Zhan, Chi; Zhou, Zhi-You; Hardacre, Christopher; Lin, Wen-Feng; Sun, Shi-Gang

    2012-12-21

    Tetrahexahedral Pt nanocrystals (THH Pt NCs), bound by high index facets, belong to an emerging class of nanomaterials that promise to bridge the gap between model and practical electrocatalysts. The atomically stepped surfaces of THH Pt NCs are extremely active for the electrooxidation of small organic molecules but they also readily accommodate the dissociative chemisorption of such species, resulting in poisoning by strongly adsorbed CO. Formic acid oxidation is an ideal reaction for studying the balance between these competing catalyst characteristics, since it can proceed by either a direct or a CO mediated pathway. Herein, we describe electrochemical and in situ FTIR spectroscopic investigations of formic acid electrooxidation at both clean and Au adatom decorated THH Pt NC surfaces. The Au decoration leads to higher catalytic currents and enhanced CO(2) production in the low potential range. As the CO oxidation behaviour of the catalyst is not improved by the presence of the Au, it is likely that the role of the Au is to promote the direct pathway. Beyond their fundamental importance, these results are significant in the development of stable, poison resistant anodic electrocatalysts for direct formic acid fuel cells.

  15. Nanoporous PdNi Alloy Nanowires As Highly Active Catalysts for the Electro-Oxidation of Formic Acid.

    PubMed

    Du, Chunyu; Chen, Meng; Wang, Wengang; Yin, Geping

    2011-02-01

    Highly active and durable catalysts for formic acid oxidation are crucial to the development of direct formic acid fuel cell. In this letter, we report the synthesis, characterization, and electrochemical testing of nanoporous Pd(57)Ni(43) alloy nanowires for use as the electrocatalyst towards formic acid oxidation (FAO). These nanowires are prepared by chemically dealloying of Ni from Ni-rich PdNi alloy nanowires, and have high surface area. X-ray diffraction data show that the Pd(57)Ni(43) nanowires have the face-centered cubic crystalline structure of pure Pd, whereas X-ray photoelectron spectroscopy confirm the modification of electronic structure of Pd by electron transfer from Ni to Pd. Electrocatalytic activity of the nanowires towards FAO exceeds that of the state-of-the-art Pd/C. More importantly, the nanowires are highly resistant to deactivation. It is proposed that the high active surface area and modulated surface properties by Ni are responsible for the improvement of activity and durability. Dealloyed nanoporous Pd(57)Ni(43) alloy nanowires are thus proposed as a promising catalyst towards FAO.

  16. Hydrogen production from formic acid decomposition at room temperature using a Ag-Pd core-shell nanocatalyst.

    PubMed

    Tedsree, Karaked; Li, Tong; Jones, Simon; Chan, Chun Wong Aaron; Yu, Kai Man Kerry; Bagot, Paul A J; Marquis, Emmanuelle A; Smith, George D W; Tsang, Shik Chi Edman

    2011-05-01

    Formic acid (HCOOH) has great potential as an in situ source of hydrogen for fuel cells, because it offers high energy density, is non-toxic and can be safely handled in aqueous solution. So far, there has been a lack of solid catalysts that are sufficiently active and/or selective for hydrogen production from formic acid at room temperature. Here, we report that Ag nanoparticles coated with a thin layer of Pd atoms can significantly enhance the production of H₂ from formic acid at ambient temperature. Atom probe tomography confirmed that the nanoparticles have a core-shell configuration, with the shell containing between 1 and 10 layers of Pd atoms. The Pd shell contains terrace sites and is electronically promoted by the Ag core, leading to significantly enhanced catalytic properties. Our nanocatalysts could be used in the development of micro polymer electrolyte membrane fuel cells for portable devices and could also be applied in the promotion of other catalytic reactions under mild conditions.

  17. Pulse electrodeposition to prepare core-shell structured AuPt@Pd/C catalyst for formic acid fuel cell application

    NASA Astrophysics Data System (ADS)

    Lu, Xueyi; Luo, Fan; Song, Huiyu; Liao, Shijun; Li, Hualing

    2014-01-01

    A novel core-shell structured AuPt@Pd/C catalyst for the electrooxidation of formic acid is synthesized by a pulse electrodeposition process, and the AuPt core nanoparticles are obtained by a NaBH4 reduction method. The catalyst is characterized with X-ray powder diffraction and transmission electron microscopy, thermogravimetric analysis, cyclic voltammetry, CO stripping and X-ray photoelectron spectroscopy. The core-shell structure of the catalyst is revealed by the increase in particle size resulting from a Pd layer covering the AuPt core, and by a negative shift in the CO stripping peaks. The addition of a small amount of Pt improves the dispersion of Au and results in smaller core particles. The catalyst's activity is evaluated by cyclic voltammetry in formic acid solution. The catalyst shows excellent activity towards the anodic oxidation of formic acid, the mass activity reaches 4.4 A mg-1Pd and 0.83 A mg-1metal, which are 8.5 and 1.6 times that of commercial Pd/C. This enhanced electrocatalytic activity could be ascribed to the good dispersion of Au core particles resulting from the addition of Pt, as well as to the interaction between the Pd shell layer and the Au and Pt in the core nanoparticles.

  18. Structural studies of Proteus mirabilis catalase in its ground state, oxidized state and in complex with formic acid.

    PubMed

    Andreoletti, Pierre; Pernoud, Anaïs; Sainz, Germaine; Gouet, Patrice; Jouve, Hélène Marie

    2003-12-01

    The structure of Proteus mirabilis catalase in complex with an inhibitor, formic acid, has been solved at 2.3 A resolution. Formic acid is a key ligand of catalase because of its ability to react with the ferric enzyme, giving a high-spin iron complex. Alternatively, it can react with two transient oxidized intermediates of the enzymatic mechanism, compounds I and II. In this work, the structures of native P. mirabilis catalase (PMC) and compound I have also been determined at high resolution (2.0 and 2.5 A, respectively) from frozen crystals. Comparisons between these three PMC structures show that a water molecule present at a distance of 3.5 A from the haem iron in the resting state is absent in the formic acid complex, but reappears in compound I. In addition, movements of solvent molecules are observed during formation of compound I in a cavity located away from the active site, in which a glycerol molecule is replaced by a sulfate. These results give structural insights into the movement of solvent molecules, which may be important in the enzymatic reaction.

  19. Photocatalytic Formic Acid Conversion on CdS Nanocrystals with Controllable Selectivity for H2 or CO**

    PubMed Central

    Kuehnel, Moritz F; Wakerley, David W; Orchard, Katherine L; Reisner, Erwin

    2015-01-01

    Formic acid is considered a promising energy carrier and hydrogen storage material for a carbon-neutral economy. We present an inexpensive system for the selective room-temperature photocatalytic conversion of formic acid into either hydrogen or carbon monoxide. Under visible-light irradiation (λ>420 nm, 1 sun), suspensions of ligand-capped cadmium sulfide nanocrystals in formic acid/sodium formate release up to 116±14 mmol H2 gcat−1 h−1 with >99 % selectivity when combined with a cobalt co-catalyst; the quantum yield at λ=460 nm was 21.2±2.7 %. In the absence of capping ligands, suspensions of the same photocatalyst in aqueous sodium formate generate up to 102±13 mmol CO gcat−1 h−1 with >95 % selectivity and 19.7±2.7 % quantum yield. H2 and CO production was sustained for more than one week with turnover numbers greater than 6×105 and 3×106, respectively. PMID:26201752

  20. Ligand-induced substrate steering and reshaping of [Ag2(H)](+) scaffold for selective CO2 extrusion from formic acid.

    PubMed

    Zavras, Athanasios; Khairallah, George N; Krstić, Marjan; Girod, Marion; Daly, Steven; Antoine, Rodolphe; Maitre, Philippe; Mulder, Roger J; Alexander, Stefanie-Ann; Bonačić-Koutecký, Vlasta; Dugourd, Philippe; O'Hair, Richard A J

    2016-06-06

    Metalloenzymes preorganize the reaction environment to steer substrate(s) along the required reaction coordinate. Here, we show that phosphine ligands selectively facilitate protonation of binuclear silver hydride cations, [LAg2(H)](+) by optimizing the geometry of the active site. This is a key step in the selective, catalysed extrusion of carbon dioxide from formic acid, HO2CH, with important applications (for example, hydrogen storage). Gas-phase ion-molecule reactions, collision-induced dissociation (CID), infrared and ultraviolet action spectroscopy and computational chemistry link structure to reactivity and mechanism. [Ag2(H)](+) and [Ph3PAg2(H)](+) react with formic acid yielding Lewis adducts, while [(Ph3P)2Ag2(H)](+) is unreactive. Using bis(diphenylphosphino)methane (dppm) reshapes the geometry of the binuclear Ag2(H)(+) scaffold, triggering reactivity towards formic acid, to produce [dppmAg2(O2CH)](+) and H2. Decarboxylation of [dppmAg2(O2CH)](+) via CID regenerates [dppmAg2(H)](+). These gas-phase insights inspired variable temperature NMR studies that show CO2 and H2 production at 70 °C from solutions containing dppm, AgBF4, NaO2CH and HO2CH.

  1. Synthesizing Pt nanoparticles in the presence of methylamine: Impact of acetic acid treatment in the electrocatalytic activity of formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Ooi, M. D. Johan; Aziz, A. Abdul

    2017-05-01

    Surfactant removal from the surface of platinum nanoparticles prepared by solution based method is a prerequisite process to accomplish a high catalytic activity for electrochemical reactions. Here, we report a possible approach of combining acid acetic with thermal treatment for improving catalytic performance of formic acid oxidation. This strategy involves conversion of amine to amide in acetic acid followed by surfactant removal via subsequent thermal treatment at 85 °C. This combined activation technique produced monodisperse nanoparticle with the size of 3 to 5 nm with enhanced formic acid oxidation activity, particularly in perchloric acid solution. Pt treated in 1 h of acetic acid and heat treatment of 9 h shows high electrochemical surface area value (27.6 m2/g) compares to Pt without activation (16.6 m2/g). The treated samples also exhibit high current stability of 0.3 mA/cm2 compares to the as-prepared mA/cm2). Shorter duration of acid wash and longer duration of heating process result in high electrocatalytic activity. This work demonstrates a possible technique in improving catalytic activity of platinum nanoparticles synthesized using methylamine as surfactant.

  2. Facile synthesis of nitrogen-doped graphene supported AuPd-CeO2 nanocomposites with high-performance for hydrogen generation from formic acid at room temperature.

    PubMed

    Wang, Zhi-Li; Yan, Jun-Min; Zhang, Yue-Fei; Ping, Yun; Wang, Hong-Li; Jiang, Qing

    2014-03-21

    AuPd-CeO2 nanocomposites directly nucleated and grown on nitrogen-doped reduced graphene oxide, exhibit excellent catalytic activity and 100% hydrogen selectivity toward formic acid decomposition for hydrogen generation without any additives at room temperature.

  3. Fabrication of a palladium nanoparticle/graphene nanosheet hybrid via sacrifice of a copper template and its application in catalytic oxidation of formic acid.

    PubMed

    Zhao, Hong; Yang, Jun; Wang, Lei; Tian, Chungui; Jiang, Baojiang; Fu, Honggang

    2011-02-21

    Small and highly dispersed palladium nanoparticles supported on graphene nanosheets were fabricated via a strategy of etching a copper template with Pd(2+). The obtained hybrid exhibited significant catalytic activity for formic acid oxidation.

  4. Deactivation/reactivation of a Pd/C catalyst in a direct formic acid fuel cell (DFAFC): Use of array membrane electrode assemblies

    NASA Astrophysics Data System (ADS)

    Yu, Xingwen; Pickup, Peter G.

    Palladium-based catalysts exhibit high activity for formic acid oxidation, but their catalytic activity decreases quite rapidly under direct formic acid fuel cell (DFAFC) operating conditions. This paper presents a systematic study of the deactivation and electrochemical reactivation of a carbon supported palladium catalyst (Pd/C) employing anode arrays in a DFAFC. Deactivation of Pd/C is caused by the electro-oxidation of the formic acid, and does not occur significantly at open circuit. Its rate increases sharply with increasing formic acid concentration but is only dependent on potential at high cell voltages. Reactivation can be achieved by driving the cell voltage to a reverse polarity of -0.2 V or higher. The use of array membrane electrode assemblies allows the rapid generation of statistically significant information on differences between catalysts, and the effects of operational parameters on the deactivation and reactivation processes.

  5. Ambient formic acid in southern California air: A comparison of two methods, Fourier transform infrared spectroscopy and alkaline trap-liquid chromatography with UV detection

    SciTech Connect

    Grosjean, D. ); Tuazon, E.C. ); Fujita, E. )

    1990-01-01

    Formic acid is an ubiquitous component of urban smog. Sources of formic acid in urban air include direct emissions from vehicles and in situ reaction of ozone with olefins. Ambient levels of formic acid in southern California air were first measured some 15 years ago by Hanst et al. using long-path Fourier transform infrared spectroscopy (FTIR). All subsequent studies of formic acid in the Los Angeles area have involved the use of two methods, either FTIR or collection on alkaline traps followed by gas chromatography, ion chromatography, or liquid chromatography analysis with UV detection, ATLC-UV. The Carbon Species Methods Comparison Study (CSMCS), a multilaboratory air quality study carried out in August 1986 at a southern California smog receptor site, provided an opportunity for direct field comparison of the FTIR and alkaline trap methods. The results of the comparison are presented in this brief report.

  6. Effects of plant species, stage of maturity, and level of formic acid addition on lipolysis, lipid content, and fatty acid composition during ensiling.

    PubMed

    Koivunen, E; Jaakkola, S; Heikkilä, T; Lampi, A-M; Halmemies-Beauchet-Filleau, A; Lee, M R F; Winters, A L; Shingfield, K J; Vanhatalo, A

    2015-09-01

    Forage type and management influences the nutritional quality and fatty acid composition of ruminant milk. Replacing grass silage with red clover (RC; L.) silage increases milk fat 18:3-3 concentration. Red clover has a higher polyphenol oxidase (PPO) activity compared with grasses, which has been suggested to decrease lipolysis and . The present study characterized the abundance and fatty acid composition of esterified lipid and NEFA before and after ensiling of grass and RC to investigate the influence of forage species, growth stage, and extent of fermentation on lipolysis. A randomized block design with a 2 × 3 × 4 factorial arrangement of treatments was used. Treatments comprised RC or a mixture of timothy ( L.) and meadow fescue ( Huds.) harvested at 3 growth stages and treated with 4 levels of formic acid (0, 2, 4, and 6 L/t). Lipid in silages treated with 0 or 6 L/t formic acid were extracted and separated into 4 fractions by TLC. Total PPO activity in fresh herbage and the content of soluble bound phenols in all silages were determined. Concentrations of 18:3-3 and total fatty acids (TFA) were higher ( < 0.001) for RC than for grass. For both forage species, 18:3-3 and TFA content decreased linearly ( < 0.001) with advancing growth stage, with the highest abundance at the vegetative stage. Most of lipid in fresh RC and grass herbage (97%) was esterified, whereas NEFA accounted for 71% of TFA in both silages. Ensiling resulted in marginal increases in TFA content and the amounts of individual fatty acids compared with fresh herbages. Herbage total PPO activity was higher ( < 0.001) for RC than grass (11 vs. 0.11 μkatal/g leaf fresh weight). Net lipolysis during ensiling was extensive for both forage species (660 to 759 g/kg fatty acid for grass and 563 to 737 g/kg fatty acid for RC). Formic acid application (0 vs. 6 L/t) resulted in a marked decrease ( = 0.026) in net lipolysis during the ensiling of RC, whereas the opposite was true ( = 0.026) for grass

  7. Graphene decorated with Pd4Ir nanocrystals: Ultrasound-assisted synthesis, and application as a catalyst for oxidation of formic acid.

    PubMed

    Zhang, Lian Ying; Liu, Ze

    2017-11-01

    An effective strategy of ultrasmall and surface-clean Pd4Ir nanocrystals uniformly decorated on graphene was developed using ultrasnoic-assisted approach. The prepared Us-Pd4Ir@Graphene reduces Pd loading while holds much higher catalytic activity and better stability toward formic acid oxidation than that of commercial Pd-C, offering great promise as a superior anode catalyst for direct formic acid fuel cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Facile one-pot surfactant-free synthesis of uniform Pd6Co nanocrystals on 3D graphene as an efficient electrocatalyst toward formic acid oxidation.

    PubMed

    Zhang, Lian Ying; Zhao, Zhi Liang; Yuan, Weiyong; Li, Chang Ming

    2016-01-28

    Ultrasmall and uniform Pd6Co nanocrystals were deposited on 3D graphene by a facile one-pot surfactant-free route for a catalyst toward formic acid oxidation, showing a much higher electrocatalytic activity, larger peak current density and better stability than Pd/3DG, Pd/C as well as commercial Pd-C, and thus offering great potential for an efficient anode catalyst toward high performance direct formic acid fuel cells.

  9. Ecosystem-scale compensation points of formic and acetic acid in the central Amazon

    NASA Astrophysics Data System (ADS)

    Jardine, K.; Yañez Serrano, A.; Arneth, A.; Abrell, L.; Jardine, A.; Artaxo, P.; Alves, E.; Kesselmeier, J.; Taylor, T.; Saleska, S.; Huxman, T.

    2011-12-01

    Organic acids, central to terrestrial carbon metabolism and atmospheric photochemistry, are ubiquitous in the troposphere in the gas, particle, and aqueous phases. As the dominant organic acids in the atmosphere, formic acid (FA, HCOOH) and acetic acid (AA, CH3COOH) control precipitation acidity in remote regions and may represent a critical link between the terrestrial carbon and water cycles by acting as key intermediates in plant carbon and energy metabolism and aerosol-cloud-precipitation interactions. However, our understanding of the exchange of these acids between terrestrial ecosystems and the atmosphere is limited by a lack of field observations, the existence of biogenic and anthropogenic primary and secondary sources whose relative importance is unclear, and the fact that vegetation can act as both a source and a sink. Here, we first present data obtained from the tropical rainforest mesocosm at Biosphere 2 which isolates primary vegetation sources. Strong light and temperature dependent emissions enriched in FA relative to AA were simultaneously observed from individual branches (FA/AA = 3.0 ± 0.7) and mesocosm ambient air (FA/AA = 1.4 ± 0.3). We also present long-term observations of vertical concentration gradients of FA and AA within and above a primary rainforest canopy in the central Amazon during the 2010 dry and 2011 wet seasons. We observed a seasonal switch from net ecosystem-scale deposition during the dry season to net emissions during the wet season. This switch was associated with reduced ambient concentrations in the wet season (FA < 1.3 nmol mol-1, AA < 2.0 nmol mol-1) relative to the dry season (FA up to 3.3 nmol mol-1, AA up to 6.0 nmol mol-1), and a simultaneous increase in the FA/AA ambient concentration ratios from 0.3-0.8 in the dry season to 1.0-2.1 in the wet season. These observations are consistent with a switch between a biomass burning dominated source in the dry season (FA/AA < 1.0) to a vegetation dominated source in the

  10. Ecosystem-scale compensation points of formic and acetic acid in the central Amazon

    NASA Astrophysics Data System (ADS)

    Jardine, K.; Yañez Serrano, A.; Arneth, A.; Abrell, L.; Jardine, A.; Artaxo, P.; Alves, E.; Kesselmeier, J.; Taylor, T.; Saleska, S.; Huxman, T.

    2011-09-01

    Organic acids, central to terrestrial carbon metabolism and atmospheric photochemistry, are ubiquitous in the troposphere in the gas, particle, and aqueous phases. As the dominant organic acids in the atmosphere, formic acid (FA, HCOOH) and acetic acid (AA, CH3COOH) control precipitation acidity in remote regions and may represent a critical link between the terrestrial carbon and water cycles by acting as key intermediates in plant carbon and energy metabolism and aerosol-cloud-precipitation interactions. However, our understanding of the exchange of these acids between terrestrial ecosystems and the atmosphere is limited by a lack of field observations, the existence of biogenic and anthropogenic primary and secondary sources whose relative importance is unclear, and the fact that vegetation can act as both a source and a sink. Here, we first present data obtained from the tropical rainforest mesocosm at Biosphere 2 which isolates primary vegetation sources. Strong light and temperature dependent emissions enriched in FA relative to AA were simultaneously observed from individual branches (FA/AA = 2.1 ± 0.6) and mesocosm ambient air (FA/AA = 1.4 ± 0.3). We also present long-term observations of vertical concentration gradients of FA and AA within and above a primary rainforest canopy in the central Amazon during the 2010 dry and 2011 wet seasons. We observed a seasonal switch from net ecosystem-scale deposition during the dry season to net emissions during the wet season. This switch was associated with reduced ambient concentrations in the wet season (FA < 1.3 nmol mol-1, AA < 2.0 nmol mol-1) relative to the dry season (FA up to 3.3 nmol mol-1, AA up to 6.0 nmol mol-1), and a simultaneous increase in the FA/AA ambient concentration ratios from 0.3-0.8 in the dry season to 1.0-2.1 in the wet season. These observations are consistent with a switch between a biomass burning dominated source in the dry season (FA/AA < 1.0) to a vegetation dominated source in the

  11. Ecosystem-Scale Compensation Point Analysis of Formic and Acetic Acid in the Central Amazon

    NASA Astrophysics Data System (ADS)

    Yanez-Serrano, A. M.; Jardine, K. J.; Arneth, A.; Abrell, L.; Jardine, A. B.; Artaxo, P.; Gomes, E.; Kesselmeier, J.; Saleska, S. R.; Huxman, T. E.

    2011-12-01

    Organic acids, central to terrestrial carbon metabolism and atmospheric photochemistry, are ubiquitous in the troposphere in the gas, particle, and aqueous phases. As the dominant organic acids in the atmosphere, formic acid (FA, HCOOH) and acetic acid (AA, CH3COOH) control precipitation acidity in remote regions and may represent a critical link between the terrestrial carbon and water cycles by acting as key intermediates in plant carbon and energy metabolism and aerosol-cloud-precipitation interactions. However, our understanding of the exchange of these acids between terrestrial ecosystems and the atmosphere is limited by a lack of field observations, the existence of biogenic and anthropogenic primary and secondary sources whose relative importance is unclear, and the fact that vegetation can act as both a source and a sink. Here, we present results from the tropical rainforest mescosom at Biosphere 2 which isolates primary vegetation sources. Strong light and temperature dependent emissions of FA and AA were simultaneously observed from individual branches and mesocosm ambient air with a strong enrichment in FA (FA/AA = 1.4 +/- 0.3, R2 of 0.89 +/- 0.10). We also present long-term observations of vertical concentration gradients of FA and AA within and above a primary rainforest canopy in central Amazonia during the 2010 dry and 2011 wet seasons. We observed a seasonal switch from net ecosystem-scale deposition during the dry season to net emissions during the wet season. This switch was associated with reduced ambient concentrations in the wet season (FA < 1.3 ppbv, AA < 2.0 ppbv) relative to the dry season (FA up to 3.3 ppbv, AA up to 6.0 ppbv), and a simultaneous increase in the FA/AA ambient concentration ratios from 0.3-0.8 in the dry season to 1.0-2.1 in the wet season. These observations are consistent with a switch between a biomass burning dominated source in the dry season (FA/AA < 1.0) to a vegetation dominated source in the wet season and call into

  12. Quantification and Evidence for Mechanically Metered Release of Pygidial Secretions in Formic Acid-Producing Carabid Beetles

    PubMed Central

    Will, Kipling W.; Gill, Aman S.; Lee, Hyeunjoo; Attygalle, Athula B.

    2010-01-01

    This study is the first to measure the quantity of pygidial gland secretions released defensively by carabid beetles (Coleoptera: Carabidae) and to accurately measure the relative quantity of formic acid contained in their pygidial gland reservoirs and spray emissions. Individuals of three typical formic acid producing species were induced to repeatedly spray, ultimately exhausting their chemical compound reserves. Beetles were subjected to faux attacks using forceps and weighed before and after each ejection of chemicals. Platynus brunneomarginatus (Mannerheim) (Platynini), P. ovipennis (Mannerheim) (Platynini) and Calathus ruficollis Dejean (Sphodrini), sprayed average quantities with standard error of 0.313 ± 0.172 mg, 0.337 ± 0.230 mg, and 0.197 ± 0.117 mg per spray event, respectively. The quantity an individual beetle released when induced to spray tended to decrease with each subsequent spray event. The quantity emitted in a single spray was correlated to the quantity held in the reservoirs at the time of spraying for beetles whose reserves are greater than the average amount emitted in a spray event. For beetles with a quantity less than the average amount sprayed in reserve there was no significant correlation. For beetles comparable in terms of size, physiological condition and gland reservoir fullness, the shape of the gland reservoirs and musculature determined that a similar effort at each spray event would mechanically meter out the release so that a greater amount was emitted when more was available in the reservoir. The average percentage of formic acid was established for these species as 34.2%, 73.5% and 34.1% for for P. brunneomarginatus, P. ovipennis and C. ruficollis, respectively. The average quantities of formic acid released by individuals of these species was less than two-thirds the amount shown to be lethal to ants in previously published experiments. However, the total quantity from multiple spray events from a single individual could

  13. Valence anions in complexes of adenine and 9-methyladenine with formic acid - stabilization by intermolecular proton transfer

    SciTech Connect

    Mazurkiewicz, Kamil; Haranczyk, Maciej; Gutowski, Maciej S; Rak, Janusz; Radisic, Dunja; Eustis, Soren; Wang, Di; Bowen, Kit H

    2007-02-07

    The photoelectron spectra of the adenine-formic acid (AFA)- and 9-methyladenine-formic acid (MAFA)- anionic complexes have been recorded with 2.540 eV photons. These spectra reveal broad features with maxima at 1.5-1.4 eV that indicate formation of stable valence anions in the gas phase. The neutral and anionic complexes of adenine/9- methyladenine and formic acid were also studied computationally at the B3LYP, second order Møller-Plesset and coupled clusters levels of theory, with the 6-31++G** and aug-cc-pVDZ basis sets. The neutral complexes form cyclic hydrogen bonds and the most stable dimers are bound by 17.7 and 16.0 kcal/mol for AFA and MAFA, respectively. The theoretical results indicate that the excess electron in both (AFA)- and (MAFA)- occupies a p* orbital localized on adenine/9-methyladenine and the adiabatic stability of the most stable anions amounts to 0.67 and 0.54 eV for AFA- and MAFA-, respectively. The excess electron attachment to the complexes induces a barrierfree proton transfer (BFPT) from the carboxylic group of formic acid to a N atom of adenine or 9-mathyladenine. As a result, the most stable structures of the anionic complexes can be characterized as neutral radicals of hydrogenated adenine(9-methyladenine) solvated by a deprotonated formic acid. The BFPT to the N atoms of adenine may be biologically relevant because some of these sites are not involved in the Watson-Crick pairing scheme and are easily accessible in the cellular environment. We suggest that valence anions of purines might be as important as those of pyrimidines in the process of DNA damage by low energy electrons. The calculations were performed at the Academic Computer Center in Gdansk (TASK) and at the Molecular Science Computing Facility (MSCF) in the William R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Department of Energy's Office of Biological and Environmental Research and located at the Pacific

  14. Quantification and evidence for mechanically metered release of pygidial secretions in formic acid-producing carabid beetles.

    PubMed

    Will, Kipling W; Gill, Aman S; Lee, Hyeunjoo; Attygalle, Athula B

    2010-01-01

    This study is the first to measure the quantity of pygidial gland secretions released defensively by carabid beetles (Coleoptera: Carabidae) and to accurately measure the relative quantity of formic acid contained in their pygidial gland reservoirs and spray emissions. Individuals of three typical formic acid producing species were induced to repeatedly spray, ultimately exhausting their chemical compound reserves. Beetles were subjected to faux attacks using forceps and weighed before and after each ejection of chemicals. Platynus brunneomarginatus (Mannerheim) (Platynini), P. ovipennis (Mannerheim) (Platynini) and Calathus ruficollis Dejean (Sphodrini), sprayed average quantities with standard error of 0.313 +/- 0.172 mg, 0.337 +/- 0.230 mg, and 0.197 +/- 0.117 mg per spray event, respectively. The quantity an individual beetle released when induced to spray tended to decrease with each subsequent spray event. The quantity emitted in a single spray was correlated to the quantity held in the reservoirs at the time of spraying for beetles whose reserves are greater than the average amount emitted in a spray event. For beetles with a quantity less than the average amount sprayed in reserve there was no significant correlation. For beetles comparable in terms of size, physiological condition and gland reservoir fullness, the shape of the gland reservoirs and musculature determined that a similar effort at each spray event would mechanically meter out the release so that a greater amount was emitted when more was available in the reservoir. The average percentage of formic acid was established for these species as 34.2%, 73.5% and 34.1% for for P. brunneomarginatus, P. ovipennis and C. ruficollis, respectively. The average quantities of formic acid released by individuals of these species was less than two-thirds the amount shown to be lethal to ants in previously published experiments. However, the total quantity from multiple spray events from a single individual

  15. Noble metal-catalyzed homogeneous and heterogeneous processes in treating simulated nuclear waste media with formic acid

    SciTech Connect

    King, R.B.; Bhattacharyya, N.K.; Smith, H.D.

    1995-09-01

    Simulants for the Hanford Waste Vitrification Plant feed containing the major non-radioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO{sub 3}{sup 2}-, NO{sub 3}-, and NO{sub 2}- were used to study reactions of formic acid at 90{degrees}C catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Such reactions were monitored using gas chromatography to analyze the CO{sub 2}, H{sub 2}, NO, and N{sub 2}O in the gas phase and a microammonia electrode to analyze the NH{sub 4}+/NH{sub 3} in the liquid phase as a function of time. The following reactions have been studied in these systems since they are undesirable side reactions in nuclear waste processing: (1) Decomposition of formic acid to CO{sub 2} + H{sub 2} is undesirable because of the potential fire and explosion hazard of H{sub 2}. Rhodium, which was introduced as soluble RhCl{sub 3}-3H{sub 2}O, was found to be the most active catalyst for H{sub 2} generation from formic acid above {approximately} 80{degrees}C in the presence of nitrite ion. The H{sub 2} production rate has an approximate pseudo first-order dependence on the Rh concentration, (2) Generation of NH{sub 3} from the formic acid reduction of nitrate and/or nitrite is undesirable because of a possible explosion hazard from NH{sub 4}NO{sub 3} accumulation in a waste processing plant off-gas system. The Rh-catalyzed reduction of nitrogen-oxygen compounds to ammonia by formic acid was found to exhibit the following features: (a) Nitrate rather than nitrite is the principal source of NH{sub 3}. (b) Ammonia production occurs at the expense of hydrogen production. (c) Supported rhodium metal catalysts are more active than rhodium in any other form, suggesting that ammonia production involves heterogeneous rather than homogeneous catalysis.

  16. A novel strategy to assemble colloidal gold nanoparticles at the water-air interface by the vapor of formic acid.

    PubMed

    Zhang, Yu-Rong; Xu, Yan-Zhen; Xia, Yue; Huang, Wei; Liu, Fa-Ai; Yang, Ying-Chang; Li, Ze-Lin

    2011-07-15

    We report a novel strategy on the controlled assembly of gold nanoparticles (NPs) at the air-water interface by designing a concentration gradient of electrolytes utilizing volatile weak acidic electrolytes. Films of close-packed Au NPs can be facilely obtained by exposing citrate-protected gold colloids to the vapor of formic acid for several hours in an airtight desiccator at room temperature. Both the higher interfacial concentration of formic acid and the buffer effect of citrate solution play the key roles in the assembly. They engender a gradient distribution of hydrogen ions such that to trigger the interfacial assembly of gold NPs while preventing the bulk colloid from aggregation and coagulation. Comparative investigations have also been performed either using other volatile electrolytes like weaker acetic acid and stronger hydrochloric acid or adding an electrolyte directly into the colloids. The as-prepared films of gold NPs can serve as good substrates for surface-enhanced Raman scattering (SERS). This strategy has also been applied to the assembly of some other NPs like colloidal Pt at the air-water interface. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Species differences in methanol and formic acid pharmacokinetics in mice, rabbits and primates

    SciTech Connect

    Sweeting, J. Nicole; Siu, Michelle; McCallum, Gordon P.; Miller, Lutfiya; Wells, Peter G.

    2010-08-15

    Methanol (MeOH) is metabolized primarily by alcohol dehydrogenase in humans, but by catalase in rodents, with species variations in the pharmacokinetics of its formic acid (FA) metabolite. The teratogenic potential of MeOH in humans is unknown, and its teratogenicity in rodents may not accurately reflect human developmental risk due to differential species metabolism, as for some other teratogens. To determine if human MeOH metabolism might be better reflected in rabbits than rodents, the plasma pharmacokinetics of MeOH and FA were compared in male CD-1 mice, New Zealand white rabbits and cynomolgus monkeys over time (24, 48 and 6 h, respectively) following a single intraperitoneal injection of 0.5 or 2 g/kg MeOH or its saline vehicle. Following the high dose, MeOH exhibited saturated elimination kinetics in all 3 species, with similar peak concentrations and a 2.5-fold higher clearance in mice than rabbits. FA accumulation within 6 h in primates was 5-fold and 43-fold higher than in rabbits and mice respectively, with accumulation being 10-fold higher in rabbits than mice. Over 48 h, FA accumulation was nearly 5-fold higher in rabbits than mice. Low-dose MeOH in mice and rabbits resulted in similarly saturated MeOH elimination in both species, but with approximately 2-fold higher clearance rates in mice. FA accumulation was 3.8-fold higher in rabbits than mice. Rabbits more closely than mice reflected primates for in vivo MeOH metabolism, and particularly FA accumulation, suggesting that developmental studies in rabbits may be useful for assessing potential human teratological risk.

  18. A facile synthesis of MPd (M = Co, Cu) nanoparticles and their catalysis for formic acid oxidation.

    PubMed

    Mazumder, Vismadeb; Chi, Miaofang; Mankin, Max N; Liu, Yi; Metin, Önder; Sun, Daohua; More, Karren L; Sun, Shouheng

    2012-02-08

    Monodisperse CoPd nanoparticles (NPs) were synthesized and studied for catalytic formic acid (HCOOH) oxidation (FAO). The NPs were prepared by coreduction of Co(acac)(2) (acac = acetylacetonate) and PdBr(2) at 260 °C in oleylamine and trioctylphosphine, and their sizes (5-12 nm) and compositions (Co(10)Pd(90) to Co(60)Pd(40)) were controlled by heating ramp rate, metal salt concentration, or metal molar ratios. The 8 nm CoPd NPs were activated for HCOOH oxidation by a simple ethanol wash. In 0.1 M HClO(4) and 2 M HCOOH solution, their catalytic activities followed the trend of Co(50)Pd(50) > Co(60)Pd(40) > Co(10)Pd(90) > Pd. The Co(50)Pd(50) NPs had an oxidation peak at 0.4 V with a peak current density of 774 A/g(Pd). As a comparison, commercial Pd catalysts showed an oxidation peak at 0.75 V with peak current density of only 254 A/g(Pd). The synthesis procedure could also be extended to prepare CuPd NPs when Co(acac)(2) was replaced by Cu(ac)(2) (ac = acetate) in an otherwise identical condition. The CuPd NPs were less active catalysts than CoPd or even Pd for FAO in HClO(4) solution. The synthesis provides a general approach to Pd-based bimetallic NPs and will enable further investigation of Pd-based alloy NPs for electro-oxidation and other catalytic reactions. © 2012 American Chemical Society

  19. Pd clusters supported on amorphous, low-porosity carbon spheres for hydrogen production from formic acid.

    PubMed

    Bulushev, Dmitri A; Bulusheva, Lyubov G; Beloshapkin, Sergey; O'Connor, Thomas; Okotrub, Alexander V; Ryan, Kevin M

    2015-04-29

    Amorphous, low-porosity carbon spheres on the order of a few micrometers in size were prepared by carbonization of squalane (C30H62) in supercritical CO2 at 823 K. The spheres were characterized and used as catalysts' supports for Pd. Near-edge X-ray absorption fine structure studies of the spheres revealed sp(2) and sp(3) hybridized carbon. To activate carbons for interaction with a metal precursor, often oxidative treatment of a support is needed. We showed that boiling of the obtained spheres in 28 wt % HNO3 did not affect the shape and bulk structure of the spheres, but led to creation of a considerable amount of surface oxygen-containing functional groups and increase of the content of sp(2) hybridized carbon on the surface. This carbon was seen by scanning transmission electron microscopy in the form of waving graphene flakes. The H/C atomic ratio in the spheres was relatively high (0.4) and did not change with the HNO3 treatment. Palladium was deposited by impregnation with Pd acetate followed by reduction in H2. This gave uniform Pd clusters with a size of 2-4 nm. The Pd supported on the original C spheres showed 2-3 times higher catalytic activity in vapor phase formic acid decomposition and higher selectivity for H2 formation (98-99%) than those for the catalyst based on the HNO3 treated spheres. Using of such low-porosity spheres as a catalyst support should prevent mass transfer limitations for fast catalytic reactions.

  20. Photo-assisted Enhancement of Formic Acid Oxidation over Platinized TiO2 Nanotube Composite

    NASA Astrophysics Data System (ADS)

    Mojumder, Nazrul I.

    1D TiO2 nanotubes (TNT) prepared by anodization deposited with 0D Pt nanoparticles (TNT--PT) prepared by a solvothermal method is used as a photoelectrocatalyst for formic acid (FA) oxidation. SEM, XRD, absorbance, EDX analysis indicates the polycrystalline TiO2 nanotubes of approximately 100+/-10 nm in diameter with 5--25 nm dimensions of Pt aggregates are formed. The composite was tested as a working electrode in the photoelectrooxidation of FA for applications such as fuel cells. Electrochemical characterization of the synthesized electrode was studied under the effect of light in order to determine the current generation of the photoactive electrode. The results show that Pt coupled with TiO 2 leads to a synergistic, i.e. boosting effect, in the increase of current density. In the presence of light, there is about a 5--fold increase in current density (75.1 mA/cm2) as compared to the absence of light (16.0 mA/cm 2). At a bias of 0.45 V the increase is about 20--fold in the presence of light (62.5 mA/cm2) compared to (3.04 mA/cm 2) in the absence of light. In addition, the effect of light in the current generation as a result of voltage bias effect is shown, thus leading to the observation that the longer the working electrode encounters light, the greater number of electrons that are generated to yield a higher current density. The study of this effect indicates a progressive current generation from light off to light on, traversing the whole range of the current generation. Thus, a combination of Helmholtz electrical double layer based limitation and mass transport limitations determine the extent of this boosting phenomenon.

  1. The chemisorption and reactions of formic acid on Cu films on ZnO (000 overline1)-O

    NASA Astrophysics Data System (ADS)

    Ludviksson, A.; Zhang, R.; Campbell, Charles T.; Griffiths, K.

    1994-06-01

    The adsorption and reactions of formic acid (HCOOD : HCOOH = 3:1) on the oxygen-terminated ZnO(0001¯)-O surface and on thin Cu films deposited on the ZnO(0001¯)-O surface have been studied with temperature programmed desorption (TPD) and XPS. Small amounts of formic acid dissociate at defect sites on clean ZnO(0001¯)-O to yield surface formate (HCOO). The acid D(H) from this dissociation does not reappear in TPD, and is lost to the ZnO bulk, as confirmed by nuclear reaction analysis. The surface HCOO decomposes to yield nearly simultaneous CO 2 (37%), CO (63%) and H 2 TPD peaks at 560 K. Substantial amounts of D (˜ 20%) are incorporated in this hydrogen TPD peak resulting from formate decomposition at ZnO defects, indicating that bulk D is readily accessible. Submonolayer and multilayer Cu films that are deposited at 130 K and partially cover the ZnO surface as 2D and 3D islands adsorb formic acid and decompose it into formate and hydrogen much like the Cu(110) surface. The surface formate from the Cu film decomposes at 470-500 K to give primarily CO 2 and H 2, also much like Cu(110), although atom-thin Cu islands also give ˜ 40% CO. Annealed Cu films give formate decomposition peaks at 25-50 K lower in temperature, attributed to thickening and ordering of the Cu islands to form Cu(111)-like sites. The acid D(H) atom from the formic acid is partially lost by hydrogen spillover from the Cu islands into the ZnO substrate, especially for thin Cu films. This effect partially desorbs and is enhanced upon preannealing the Cu layers, due to increased H diffusion rates across the annealed Cu islands, and/or the decrease in island size. Bulk D(H) is slowly removed as D 2, HD and H 2 above 400 K in diffusion-limited desorption, catalyzed by Cu.

  2. Protein preservation and ruminal degradation of ensiled forage treated with heat, formic acid, ammonia, or microbial inoculant.

    PubMed

    Polan, C E; Stieve, D E; Garrett, J L

    1998-03-01

    The objectives of this study were to determine whether treatment of forage with heat would reduce proteolysis during subsequent fermentation. In Experiment 1, direct-cut barley forage and alfalfa were untreated, microwaved, or steamed and then ensiled in laboratory silos as wilted forages. Silages of microwaved or steamed forage showed a marked increase in N bound to neutral detergent fiber and in the recovery of protein; however, alfalfa silages also had high pH values and concentrations of butyric acid. In Experiment 2, steam heating was compared with formic acid and NH3 treatments for the prevention of proteolysis in alfalfa silages. Silage of steamed alfalfa had a greater amount of N bound to neutral detergent fiber and greater recovery of protein than did control silage or silages of forage treated with formic acid or NH3. Silage of steamed forage had lower pH values than did silages of wilted, direct-cut, or control forage. Microbial innoculant added to steamed forage increased the recovery of protein. Silage of steamed forage had less aerobic stability than did silage of direct-cut forage. Ruminal degradability of crude protein (CP) and organic matter of silage from both experiments was evaluated. Degradability of CP was 8 to 26 percentage units lower in silages of microwaved or steamed forage in Experiment 1 than in silage of unheated forage because of slower degradation rates, but all had similar undegraded CP after incubation for 72 h. In Experiment 2, wilting, steam, formic acid, and NH3 treatments affected CP degradability similarly, but CP degradability was decreased when compared with silage of direct-cut forage without treatment.

  3. Dual hydrogen-bonding motifs in complexes formed between tropolone and formic acid

    NASA Astrophysics Data System (ADS)

    Nemchick, Deacon J.; Cohen, Michael K.; Vaccaro, Patrick H.

    2016-11-01

    The near-ultraviolet π*←π absorption system of weakly bound complexes formed between tropolone (TrOH) and formic acid (FA) under cryogenic free-jet expansion conditions has been interrogated by exploiting a variety of fluorescence-based laser-spectroscopic probes, with synergistic quantum-chemical calculations built upon diverse model chemistries being enlisted to unravel the structural and dynamical properties of the pertinent ground [X˜ 1A'] and excited [A˜ 1A'(" separators="π*π )] electronic states. For binary TrOH ṡ FA adducts, the presence of dual hydrogen-bond linkages gives rise to three low-lying isomers designated (in relative energy order) as INT, EXT1, and EXT2 depending on whether docking of the FA ligand to the TrOH substrate takes place internal or external to the five-membered reaction cleft of tropolone. While the symmetric double-minimum topography predicted for the INT potential surface mediates an intermolecular double proton-transfer event, the EXT1 and EXT2 structures are interconverted by an asymmetric single proton-transfer process that is TrOH-centric in nature. The A ˜ -X ˜ origin of TrOH ṡ FA at ν˜ 00=27 484 .45 cm-1 is displaced by δ ν˜ 00=+466 .76 cm-1 with respect to the analogous feature for bare tropolone and displays a hybrid type - a/b rotational contour that reflects the configuration of binding. A comprehensive analysis of vibrational landscapes supported by the optically connected X˜ 1A' and A˜ 1A'(" separators="π*π ) manifolds, including the characteristic isotopic shifts incurred by partial deuteration of the labile TrOH and FA protons, has been performed leading to the uniform assignment of numerous intermolecular (viz., modulating hydrogen-bond linkages) and intramolecular (viz., localized on monomer subunits) degrees of freedom. The holistic interpretation of all experimental and computational findings affords compelling evidence that an external-binding motif (attributed to EXT1), rather than the

  4. Electrocatalytic Oxidation of Formic Acid in an Alkaline Solution with Graphene-Oxide- Supported Ag and Pd Alloy Nanoparticles.

    PubMed

    Han, Hyoung Soon; Yun, Mira; Jeong, Haesang; Jeon, Seungwon

    2015-08-01

    The electrocatalytic activities of metal-decorated graphene oxide (GO) catalysts were investigated. Electrochemically reduced GO-S-(CH2)4-S-Pd [ERGO-S-(CH2)4-S-Pd] and GO-S-(CH2)4-S-PdAg alloy [ERGO-S-(CH2)4-S-PdAg] were obtained through the electrochemical reduction of GO-S-(CH2)4-S-Pd and GO-S-(CH2)4-S-PdAg in a pH 5 PBS solution. It was demonstrated that the application of ERGO-S-(CH2)4-S-Pd and ERGO-S-(CH2)4-S-PdAg used in a modified GCE improves the electrocatalytic oxidation of formic acid. The addition of an Ag nanoparticle with a carbon chain-Pd in the electrode provides an electrode with very interesting properties for the electrocatalytic oxidation of formic acid. The ERGO-S-(CH2)4-S-Pd and ERGO-S-(CH2)4-S-PdAg were characterized via X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). ERGO-S-(CH2)4-S-Pd and ERGO-S-(CH2)4-S-PdAg can be employed for the electrocatalytic oxidation of formic acid. The electrochemical behaviors of this electrode were investigated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS).

  5. PdCo supported on multiwalled carbon nanotubes as an anode catalyst in a microfluidic formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Morales-Acosta, D.; Morales-Acosta, M. D.; Godinez, L. A.; Álvarez-Contreras, L.; Duron-Torres, S. M.; Ledesma-García, J.; Arriaga, L. G.

    This work reports the synthesis of Pd-based alloys of Co and their evaluation as anode materials in a microfluidic formic acid fuel cell (μFAFC). The catalysts were prepared using the impregnation method followed by thermal treatment. The synthesized catalysts contain 22 wt.% Pd on multiwalled carbon nanotubes (Pd/MWCNT) and its alloys with two Co atomic percent in the sample with 4 at.% Co (PdCo1/MWCNT) and 10 at.% Co (PdCo2/MWCNT). The role of the alloying element was determined by XRD and XPS techniques. Both catalysts were evaluated as anode materials in a μFAFC operating with different concentrations of HCOOH (0.1 and 0.5 M), and the results were compared to those obtained with Pd/MWCNT. A better performance was obtained for the cell using PdCo1/MWCNT (1.75 mW cm -2) compared to Pd/MWCNT (0.85 mW cm -2) in the presence of 0.5 M HCOOH. By means of external electrode measurements, it was also possible to observe shifts in the formic acid oxidation potential due to a fuel concentration increment (ca. 0.05 V for both PdCo1/MWCNT and PdCo2/MWCNT catalysts and 0.23 V for Pd/MWCNT) that was attributed to deactivation of the catalyst material. The maximum current densities obtained were 8 mA cm -2 and 5.2 mA cm -2 for PdCo2/MWCNT and Pd/MWCNT, respectively. In this way, the addition of Co to the Pd catalyst was shown to improve the tolerance of intermediates produced during formic acid oxidation that tend to poison Pd, thus improving the catalytic activity and stability of the cell.

  6. Oxidation of formic acid and carbon monoxide on gold electrodes studied by surface-enhanced Raman spectroscopy and DFT.

    PubMed

    Beltramo, Guillermo L; Shubina, Tatyana E; Koper, Marc T M

    2005-12-09

    The oxidation of formic acid and carbon monoxide was studied at a gold electrode by a combination of electrochemistry, in situ surface-enhanced Raman spectroscopy (SERS), differential electrochemical mass spectrometry, and first-principles DFT calculations. Comparison of the SERS results and the (field-dependent) DFT calculations strongly suggests that the relevant surface-bonded intermediate during oxidation of formic acid on gold is formate HCOO- ad*. Formate reacts to form carbon dioxide via two pathways: at low potentials, with a nearby water to produce carbon dioxide and a hydronium ion; at higher potentials, with surface-bonded hydroxyl (or oxide) to give carbon dioxide and water. In the former pathway, the rate-determining step is probably related to the reaction of surface-bonded formate with water, as measurements of the reaction order imply a surface almost completely saturated with adsorbate. The potential dependence of the rate of the low-potential pathway is presumably governed by the potential dependence of formate coverage. There is no evidence for CO formation on gold during oxidation of formic acid. The oxidation of carbon monoxide must involve the carboxyhydroxyl intermediate, but SERS measurements do not reveal this intermediate during CO oxidation, most likely because of its low surface coverage, as it is formed after the rate-determining step. Based on inconclusive spectroscopic evidence for the formation of surface-bonded OH at potentials substantially below the surface oxidation region, the question whether surface-bonded carbon monoxide reacts with surface hydroxyl or with water to form carboxyhydroxyl and carbon dioxide remains open. The SERS measurements show the existence of both atop and bridge-bonded CO on gold from two distinguishable low-frequency modes that agree very well with DFT calculations.

  7. Adsorption and thermal chemistry of formic acid on clean and oxygen-predosed Cu(110) single-crystal surfaces revisited

    NASA Astrophysics Data System (ADS)

    Yao, Yunxi; Zaera, Francisco

    2016-04-01

    The thermal chemistry of formic acid on clean and oxygen-predosed Cu(110) single-crystal surfaces was studied under ultrahigh-vacuum (UHV) conditions by temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). Key results reported in the past were confirmed, including the partial switchover from H2 to H2O desorption upon oxygen addition on the surface and the development of a second decomposition regime at 420 K, in addition to the one observed at 460 K on the clean substrate. In addition, new observations were added, including the previously missed desorption of H2 at 420 K and the existence of a normal kinetic isotope effect in both TPD peaks. Peak fitting of the XPS data afforded the identification of an asymmetric geometry for the formate intermediate, which was established to form by 200 K, and the presence of coadsorbed molecular formic acid up to the temperatures of decomposition, probably in a second layer and held by hydrogen bonding. Quantitative analysis of the TPD data indicated a one-to-one correspondence between the increase in oxygen coverage beyond θO = 0.5 ML and a decrease in formic acid uptake that mainly manifests itself in a decrease in the decomposition seen in the 460 K TPD peak. All these observations were interpreted in terms of a simple decomposition mechanism involving hydrogen abstraction from adsorbed formate species, possibly aided by coadsorbed oxygen, and a change in reaction activation energy as a function of the structure of the oxygen overlayer, which reverts from a O-c(6 × 2) structure at high oxygen coverages to the O-(2 × 1) order seen at θO = 0.5 ML.

  8. Quantitative determination of caffeine, formic acid, trigonelline and 5-(hydroxymethyl)furfural in soluble coffees by 1H NMR spectrometry.

    PubMed

    del Campo, Gloria; Berregi, Iñaki; Caracena, Raúl; Zuriarrain, Juan

    2010-04-15

    A quantitative method for the determination of caffeine, formic acid, trigonelline and 5-(hydroxymethyl)furfural (5-HMF) in soluble coffees by applying the proton nuclear magnetic resonance technique ((1)H NMR) is proposed. Each of these compounds records a singlet signal at the 7.6-9.5 ppm interval of the spectrum, and its area is used to determine the concentration. 3-(Trimethylsilyl)-2,2,3,3-tetradeuteropropionic acid is added in an exact known concentration as a reference for delta=0.00 ppm and as an internal standard. The method is applied to commercial soluble coffees and satisfactorily compared with results obtained by standard methods. The limits of detection and the coefficients of variation (N=10) are, respectively, 1.32 mg/g of solid product and 4.2% for caffeine, 0.45 mg/g and 2.6% for formic acid, 0.58 mg/g and 2.4% for trigonelline, and 0.30 mg/g and 7.3% for 5-HMF. The described method is direct and no previous derivatization is needed.

  9. Facile and rapid synthesis of spherical porous palladium nanostructures with high catalytic activity for formic acid electro-oxidation.

    PubMed

    Tang, Shaochun; Vongehr, Sascha; Zheng, Zhou; Ren, Hua; Meng, Xiangkang

    2012-06-29

    Highly uniform, spherical porous palladium nanostructures (SPPNs) with rough surfaces were prepared by a facile and rapid ultrasound assisted reduction. The synthesis involves sonicating a solution of K(2)PdCl(4) and ascorbic acid for only 7 min at 40 °C without any additives. The products are isolated structures with a narrow size distribution, and their average diameters are controllable in a range from 40 to 100 nm via the K(2)PdCl(4) concentration. Typical products have a diameter of 52 nm and consist of loosely packed grains of 2-3 nm. They are thus very porous, with a specific surface area of 47 m(2) g(-1). The growth mechanism of SPPNs is discussed on the basis of varying relevant reaction parameters and characterizations from different microscopy techniques, nitrogen absorption analysis, and time-dependent UV-vis spectra. The electrocatalytic performance of the SPPNs was evaluated by electro-oxidation of formic acid. The mass current density per mass of SPPNs (1.88 A mg(-1)) exceeds that of commercial Pd black (1.69 A mg(-1)) and is more than twice that of commercial Pd/C catalyst (0.79 A mg(-1)). Long-term stability of the activity makes this material a promising anode catalyst for direct formic acid fuel cells.

  10. Facile and rapid synthesis of spherical porous palladium nanostructures with high catalytic activity for formic acid electro-oxidation

    NASA Astrophysics Data System (ADS)

    Tang, Shaochun; Vongehr, Sascha; Zheng, Zhou; Ren, Hua; Meng, Xiangkang

    2012-06-01

    Highly uniform, spherical porous palladium nanostructures (SPPNs) with rough surfaces were prepared by a facile and rapid ultrasound assisted reduction. The synthesis involves sonicating a solution of K2PdCl4 and ascorbic acid for only 7 min at 40 °C without any additives. The products are isolated structures with a narrow size distribution, and their average diameters are controllable in a range from 40 to 100 nm via the K2PdCl4 concentration. Typical products have a diameter of 52 nm and consist of loosely packed grains of 2-3 nm. They are thus very porous, with a specific surface area of 47 m2 g-1. The growth mechanism of SPPNs is discussed on the basis of varying relevant reaction parameters and characterizations from different microscopy techniques, nitrogen absorption analysis, and time-dependent UV-vis spectra. The electrocatalytic performance of the SPPNs was evaluated by electro-oxidation of formic acid. The mass current density per mass of SPPNs (1.88 A mg-1) exceeds that of commercial Pd black (1.69 A mg-1) and is more than twice that of commercial Pd/C catalyst (0.79 A mg-1). Long-term stability of the activity makes this material a promising anode catalyst for direct formic acid fuel cells.

  11. Non-hydrolytic formation of silica and polysilsesquioxane particles from alkoxysilane monomers with formic acid in toluene/tetrahydrofuran solutions

    NASA Astrophysics Data System (ADS)

    Boday, Dylan J.; Tolbert, Stephanie; Keller, Michael W.; Li, Zhe; Wertz, Jason T.; Muriithi, Beatrice; Loy, Douglas A.

    2014-03-01

    Silica and polysilsesquioxane particles are used as fillers in composites, catalyst supports, chromatographic separations media, and even as additives to cosmetics. The particles are generally prepared by hydrolysis and condensation of tetraalkoxysilanes and/or organotrialkoxysilanes, respectively, in aqueous alcohol solutions. In this study, we have discovered a new, non-aqueous approach to prepare silica and polysilsesquioxane particles. Spherical, nearly monodisperse, silica particles (600-6,000 nm) were prepared from the reaction of tetramethoxysilane with formic acid (4-8 equivalents) in toluene or toluene/tetrahydrofuran solutions. Polymerization of organotrialkoxysilanes with formic acid failed to afford particles, but bridged polysilsesquioxane particles were obtained from monomers with two trialkoxysilyl group attached to an organic-bridging group. The mild acidic conditions allowed particles to be prepared from monomers, such as bis(3-triethoxysilylpropyl)tetrasulfide, which are unstable to Stöber or base-catalyzed emulsion polymerization conditions. The bridged polysilsesquioxane particles were generally less spherical and more polydisperse than silica particles. Both silica and bridged polysilsesquioxane nanoparticles could be prepared in good yields at monomer concentrations considerably higher than used in Stöber or emulsion approaches.

  12. Modeling and spectral simulation of matrix-isolated molecules by density functional calculations: A case study on formic acid dimer

    NASA Astrophysics Data System (ADS)

    Ito, Fumiyuki

    2010-12-01

    The supermolecule approach has been used to model molecules embedded in solid argon matrix, wherein interaction between the guest and the host atoms in the first solvation shell is evaluated with the use of density functional calculations. Structural stability and simulated spectra have been obtained for formic acid dimer (FAD)-Arn (n = 21-26) clusters. The calculations at the B971/6-31++G(3df,3pd) level have shown that the tetrasubstitutional site on Ar(111) plane is likely to incorporate FAD most stably, in view of consistency with the matrix shifts available experimentally.

  13. Reexamination of CO formation during formic acid decomposition on the Pt(1 1 1) surface in the gas phase

    NASA Astrophysics Data System (ADS)

    Wang, Yingying; Zhang, Dongju; Liu, Peng; Liu, Chengbu

    2016-08-01

    Existing theoretical results for formic acid (HCOOH) decomposition on Pt(1 1 1) cannot rationalize the easy CO poisoning of the catalysts in the gas phase. The present work reexamined HCOOH decomposition on Pt(1 1 1) by considering the effect of the initial adsorption structure of the reactant on the reactivity. Our calculations present a new adsorption configuration of HCOOH on Pt(1 1 1), from which the formation of CO is found to be competing with the formation of CO2. The newly proposed mechanism improves our understanding for the mechanism of HCOOH decomposition catalyzed by Pt-based catalysts.

  14. Synthesis of cubic PtPd alloy nanoparticles as anode electrocatalysts for methanol and formic acid oxidation reactions.

    PubMed

    Lee, Jin-Yeon; Kwak, Da-Hee; Lee, Young-Woo; Lee, Seul; Park, Kyung-Won

    2015-04-14

    The electrocatalytic properties for electro-oxidation reactions of shape-controlled Pt-based catalysts have been improved by alloying with 2nd elements. In this study, we demonstrate cubic PtPd alloy nanoparticles synthesized using a thermal decomposition method. The cubic PtPd nanoparticles exhibit a homogeneous distribution of alloy nanostructures in the presence of Pt and Pd metallic phases. The improved electrocatalytic activity for the electro-oxidation reactions of methanol and formic acid as chemical fuels might be attributed to the cubic alloy nanostructures. Furthermore, the cubic PtPd alloy nanoparticles as electrocatalysts exhibit excellent stability for electro-oxidation reactions.

  15. The role of surface functionalities in fabricating supported Pd-P nanoparticles for efficient formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Yu, Weizhen; Xin, Zhiling; Zhang, Wei; Xie, Yanan; Wang, Juan; Niu, Shuo; Wu, Yifei; Shao, Lidong

    2017-10-01

    In the present work, O-functionalized carbon nanotubes (OCNTs) supported Pd-P nanoparticles (Pd-P/OCNTs) were prepared by using sodium hypophosphite (NaH2PO2) as the P source and the reducing agent. The presence of O-functionalities on the carbon surface provide a microenvironment of the reaction system which favors the anchorage of P precursors and Pd salt ions through the electrostatic interaction and the formation of chemical bonds on the carbon support. Thus, Pd nanoparticles supported on the OCNTs could be efficiently incorporated with P. Pd with the modified outer electron structure enhanced the electrocatalytic performance for formic acid oxidation (FAO).

  16. Coefficient of ozone mass transfer during its interaction with an aqueous solution of formic acid in a bubble column reactor

    NASA Astrophysics Data System (ADS)

    Levanov, A. V.; Isaikina, O. Ya.; Gasanova, R. B.; Lunin, V. V.

    2017-08-01

    A way of determining the coefficient of ozone mass transfer between the gas phase and liquid aqueous phase using a test compound (formic acid) is described. The values of ozone mass transfer coefficient (in aqueous solutions of 0.1-0.55 M HClO4 and 0-1 M HCOOH, and in 0.75 M H2SO4, 0.125 M KHSO4, and 0-2 M HCOOH) are determined along with the rate constants of the reaction of O3 with undissociated HCOOH molecules and formate ions at 21 ± 1°C.

  17. Direct evidence for active site-dependent formic acid electro-oxidation by topmost-surface atomic redistribution in a ternary PtPdCu electrocatalyst.

    PubMed

    Cui, Chun-Hua; Li, Hui-Hui; Cong, Huai-Ping; Yu, Shu-Hong; Tao, Franklin Feng

    2012-12-25

    The active site-dependent electrochemical formic acid oxidation was evidenced by the increased coverage of Pt in the topmost mixed PtPd alloy layer of ternary PtPdCu upon potential cycling, which demonstrated two catalytic pathways only in one catalyst owing to surface atomic redistribution in an acidic electrolyte environment.

  18. Electro-oxidation of methanol and formic acid on PtRu and PtAu for direct liquid fuel cells

    NASA Astrophysics Data System (ADS)

    Choi, Jong-Ho; Jeong, Kyoung-Jin; Dong, Yujung; Han, Jonghee; Lim, Tae-Hoon; Lee, Jae-Suk; Sung, Yung-Eun

    The use of a PtAu catalyst as an anode catalyst for the oxidation of formic acid in direct formic acid fuel cells is described. Catalytic activities of PtAu and PtRu anodes were studied using a linear sweep voltammetry technique in a single cell configuration. PtAu showed a lower on-set potential and a larger current density than that of PtRu in formic acid oxidation. In addition, the maximum power densities at 30 °C for PtAu and PtRu were 94 and 74 mW cm -2, respectively. In order to evaluate long-term durability, the single cells were operated for hundreds of hours with a 6 M aqueous formic acid solution at 60 °C under 100 mA cm -2. The difference in performance between PtAu and PtRu after 500 h reached ca. 90 mV in direct formic acid fuel cells.

  19. Direct determination of mercury in cosmetic samples by isotope dilution inductively coupled plasma mass spectrometry after dissolution with formic acid.

    PubMed

    Gao, Ying; Shi, Zeming; Zong, Qinxia; Wu, Peng; Su, Jing; Liu, Rui

    2014-02-17

    A new method was proposed for the accurate determination of mercury in cosmetic samples based on isotopic dilution (ID)-photochemical vapor generation (PVG)-inductively coupled plasma mass spectrometry (ICP MS) measurement. Cosmetic samples were directly dissolved in formic acid solution and subsequently subjected to PVG for the reduction of mercury into vapor species following by ICP MS detection. Therefore, the risks of analyte contamination and loss were avoided. Highly enriched (201)Hg isotopic spike is added to cosmetics and the isotope ratios of (201)Hg/(202)Hg were measured for the quantitation of mercury. With ID calibration, the influences originating from sample matrixes for the determination of mercury in cosmetic samples have been efficiently eliminated. The effects of several experimental parameters, such as the concentration of the formic acid, and the flow rates of carrier gas and sample were investigated. The method provided good reproducibility and the detection limits were found to be 0.6 pg mL(-1). Finally, the developed method was successfully applied for the determination of mercury in six cosmetic samples and a spike test was performed to verify the accuracy of the method. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Aerobic oxidation of methanol to formic acid on Au20-: a theoretical study on the reaction mechanism.

    PubMed

    Bobuatong, Karan; Karanjit, Sangita; Fukuda, Ryoichi; Ehara, Masahiro; Sakurai, Hidehiro

    2012-03-07

    The aerobic oxidation of methanol to formic acid catalyzed by Au(20)(-) has been investigated quantum chemically using density functional theory with the M06 functional. Possible reaction pathways are examined taking account of full structure relaxation of the Au(20)(-) cluster. The proposed reaction mechanism consists of three elementary steps: (1) formation of formaldehyde from methoxy species activated by a superoxo-like anion on the gold cluster; (2) nucleophilic addition by the hydroxyl group of a hydroperoxyl-like complex to formaldehyde resulting in a hemiacetal intermediate; and (3) formation of formic acid by hydrogen transfer from the hemiacetal intermediate to atomic oxygen attached to the gold cluster. A comparison of the computed energetics of various elementary steps indicates that C-H bond dissociation of the methoxy species leading to formation of formaldehyde is the rate-determining step. A possible reaction pathway involving single-step hydrogen abstraction, a concerted mechanism, is also discussed. The stabilities of reactants, intermediates and transition state structures are governed by the coordination number of the gold atoms, charge distribution, cooperative effect and structural distortion, which are the key parameters for understanding the relationship between the structure of the gold cluster and catalytic activity in the aerobic oxidation of alcohols.

  1. Hydrogen bonding in electronically excited states: a comparison between formic acid dimer and its mono-substituted thioderivatives.

    PubMed

    Cimas, Alvaro; Mó, Otilia; Yáñez, Manuel; Martín, Nazario; Corral, Inés

    2010-10-28

    A multi-state complete active space second order perturbation theory (MS-CASPT2) study on the valence singlet electronic excited states of formic acid dimer is presented. The electronic spectrum of this dihydrogen bonded system is dominated by nπ* and ππ* intramonomer and charge transfer excitations and consists of a very intense ππ* transition at 8.25 eV and three weaker nπ*(2×) and ππ*(1×) electronic excitations at 6.21 eV, 9.13 eV, and 9.93 eV, respectively. The characteristic nπ*-nπ*-ππ*-ππ*… pattern found in the formic acid dimer electronic spectrum is altered when a sulfur atom is introduced in the molecule. Furthermore, carbonyl-by-thiocarbonyl or hydroxyl-by-thiohydroxyl substitution is predicted to strongly affect the intensity of the above electronic transitions. The effect of oxygen-by-sulfur substitution on the geometry of the first excited state (S(1)) has been investigated at the CC2 and CASSCF levels of theory. Although the two methods qualitatively predict the same geometrical changes upon nπ* excitation, the geometries of the S(1) state are found to differ considerably between the two levels.

  2. Electrocatalytic oxidation of formic acid by poly(diallyldimethylammonium chloride) and Pt/Pd-functionalized carbon nanotubes mixtures.

    PubMed

    Kim, Min-Su; Kim, Daekun; Lee, Hyo Kyoung; Jeon, Seungwon

    2012-12-01

    Improving the catalytic activity of the anode catalyst is an important task in the direct formic acid fuel cell (DFAFC). In this study, the catalysts were prepared by dispersing either platinum or palladium metal on the surface of thiolated multi-walled carbon nanotubes (t-MWCNTs), denoted as t-MWCNT-Pt and t-MWCNT-Pd, respectively. These modified t-MWCNT and poly(diallyldimethylammonium chloride) (PDDA) were ultrasonically mixed and loading on a glassy carbon electrode (GCE) for formic acid (FA) oxidation and the catalytic activities were then investigated by using cyclic voltammetry (CV) and chronoamperometry (CA) methods. The as-formed catalysts were characterized by several methods. To optimize the catalytic performance, we investigated the catalysts separately and together (in different ratios) for FA oxidation. The PDDA mixed catalyst demonstrated a slightly better performance. These results indicated that the PDDA/(t-MWCNT-Pt + t-MWCNT-Pd) catalyst exhibited better activity than that of the corresponding other catalysts.

  3. Wet air oxidation of formic acid using nanoparticle-modified polysulfone hollow fibers as gas-liquid contactors.

    PubMed

    Hogg, Seth R; Muthu, Satish; O'Callaghan, Michael; Lahitte, Jean-Francois; Bruening, Merlin L

    2012-03-01

    Catalytic wet air oxidation (CWAO) using membrane contactors is attractive for remediation of aqueous pollutants, but previous studies of even simple reactions such as formic acid oxidation required multiple passes through tubular ceramic membrane contactors to achieve high conversion. This work aims to increase single-pass CWAO conversions by using polysulfone (PS) hollow fibers as contactors to reduce diffusion distances in the fiber lumen. Alternating adsorption of polycations and citrate-stabilized platinum colloids in fiber walls provides catalytically active PS hollow fibers. Using a single PS fiber, 50% oxidation of a 50 mM formic acid feed solution results from a single pass through the fiber lumen (15 cm length) with a solution residence time of 40 s. Increasing the number of PS fibers to five while maintaining the same volumetric flow rate leads to over 90% oxidation, suggesting that further scale up in the number of fibers will facilitate high single pass conversions at increased flow rates. The high conversion compared to prior studies with ceramic fibers stems from shorter diffusion distances in the fiber lumen. However, the activity of the Pt catalyst is 20-fold lower than in previous ceramic fibers. Focusing the Pt deposition near the fiber lumen and limiting pore wetting to this region might increase the activity of the catalyst. © 2012 American Chemical Society

  4. One-pot synthesis of intermetallic electrocatalysts in ordered, large-pore mesoporous carbon/silica toward formic acid oxidation.

    PubMed

    Shim, Jongmin; Lee, Jaehyuk; Ye, Youngjin; Hwang, Jongkook; Kim, Soo-Kil; Lim, Tae-Hoon; Wiesner, Ulrich; Lee, Jinwoo

    2012-08-28

    This study describes the one-pot synthesis and single-cell characterization of ordered, large-pore (>30 nm) mesoporous carbon/silica (OMCS) composites with well-dispersed intermetallic PtPb nanoparticles on pore wall surfaces as anode catalysts for direct formic acid fuel cells (DFAFCs). Lab-synthesized amphiphilic diblock copolymers coassemble hydrophobic metal precursors as well as hydrophilic carbon and silica precursors. The final materials have a two-dimensional hexagonal-type structure. Uniform and large pores, in which intermetallic PtPb nanocrystals are significantly smaller than the pore size and highly dispersed, enable pore backfilling with ionomers and formation of the desired triple-phase boundary in single cells. The materials show more than 10 times higher mass activity and significantly lower onset potential for formic acid oxidation as compared with commercial Pt/C, as well as high stability due to better resistivity toward CO poisoning. In single cells, the maximum power density was higher than that of commercial Pt/C, and the stability highly improved, compared with commercial Pd/C. The results suggest that PtPb-based catalysts on large-pore OMCSs may be practically applied as real fuel cell catalysts for DFAFC.

  5. Electrocatalytic performance of carbon supported Pd catalyst modified with Keggin type of Sn-substituted polyoxometalatate for formic acid oxidization

    NASA Astrophysics Data System (ADS)

    Ji, Yun; Shen, Liping; Wang, Anxing; Wu, Min; Tang, Yawen; Chen, Yu; Lu, Tianhong

    2014-08-01

    The carbon supported Pd(Pd/C) catalyst modified by the new polyoxometalate with Keggin type of Sn-Substituted structure K7CoIIW11O39SnIVOH (Pd/C-K7) catalyst is prepared with the simple impregnation-reduction method. This work investigates the effects of Pd/C-K7 catalyst for direct formic acid fuel cells (DFAFCs). The morphology, structure, size and composition of the Pd/C-K7 catalyst are characterized by transmission electron microscopy (TEM) energy dispersive spectrum (EDS), X-ray diffraction (XRD). Cyclic voltammetry, chronoamperometry and CO-stripping voltammetry tests demonstrate the Pd/C-K7 catalyst have higher electrocatalytic activity, better electrochemical stability, and higher resistance to CO poisoning over the unmodified Pd/C catalyst for the formic acid oxidation reaction (FAOR) owing to K7CoIIW11O39SnIVOH with Keggin structure. Therefore, the Pd/C-K7 catalyst could be used as the excellent anodic catalyst in DFAFCs.

  6. Exploring Relative Thermodynamic Stabilities of Formic Acid and Formamide Dimers - Role of Low-Frequency Hydrogen-Bond Vibrations.

    PubMed

    Cato, Michael A; Majumdar, D; Roszak, Szczepan; Leszczynski, Jerzy

    2013-02-12

    The low-frequency fundamentals together with the high-frequency modes, responsible for hydrogen bonding (OH/NH stretching modes), were analyzed to correlate the intensities with the hydrogen-bond strengths/binding energies of the formic acid and formamide dimers using Møller-Plesset second-order perturbation (MP2) and coupled cluster computations with explicit anharmonicity corrections. Linear correlations were observed for both the formic acid and formamide dimers, and as consequence of such correlation an additive properties of binding energies with respect to the local hydrogen-bond energies of fragments involved (for these dimers) has been proposed. It has been further observed that (i) the nature of their six low-frequency fundamentals are very similar, and (ii) the in-plane bending and stretch-bend fundamentals of different dimers of these two species (depending on the dimer structure), in this low-frequency region, modulate their strength of hydrogen-bond/binding hence their relative stability order. These results were further verified against the results from Gaussian-G4-MP2 (G4MP2), Gaussian-G2-MP2 (G2MP2), and complete basis set (CBS-QB3) methods of high accuracy energy calculations.

  7. Boron Nitride-supported Sub-nanometer Pd 6 Clusters for Formic Acid Decomposition: A DFT Study

    DOE PAGES

    Schimmenti, Roberto; Cortese, Remedios; Duca, Dario; ...

    2017-04-25

    A periodic, self-consistent planewave DFT study was carried out to explore the potential use of Pd6 clusters supported on a boron nitride sheet as a catalyst for the selective decomposition of formic acid (HCOOH) to CO2 and H2. The competition between formate (HCOO) and carboxyl (COOH) paths on catalytic sites, with different proximities to the support, was studied. Based on energetics alone, the reaction may mainly follow the HCOO route. Slightly lower activation energies were found at the lateral sites of the cluster as compared to top face sites. This is particularly true for the bidentate to monodentate HCOO conversion.more » Through comparison of results with similar studies on HCOOH decomposition on extended Pd surfaces, it was demonstrated that the existence of undercoordinated sites in the sub-nanometer cluster could play a key role in preferentially stabilizing HCOO over COOH, which is a common CO precursor in this reaction. A hydrogen spillover mechanism was also investigated; migration toward the boron nitride support is not favorable, at least in the early stages of the reaction. However, hydrogen diffusion on the cluster has low barriers compared to those involved in formic acid decomposition.« less

  8. Carbon nanotube/raspberry hollow Pd nanosphere hybrids for methanol, ethanol, and formic acid electro-oxidation in alkaline media.

    PubMed

    Liu, Zhelin; Zhao, Bo; Guo, Cunlan; Sun, Yujing; Shi, Yan; Yang, Haibin; Li, Zhuang

    2010-11-01

    In this paper, raspberry hollow Pd nanospheres (HPNs)-decorated carbon nanotube (CNT) was developed for electro-oxidation of methanol, ethanol, and formic acid in alkaline media. The electrocatalyst was fabricated simply by attaching HPNs onto the surface of CNT which had been functionalized by polymer wrapping. The as-prepared HPN-CNTs (CHPNs) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The increasing interest and intensive research on fuel cell inspire us to investigate the electrocatalytic properties of the prepared nanostructures. Besides that, previous reports about alkaline other than acidic media could supply a more active environment guide us to examine the electrocatalytic properties in alkaline electrolyte. It is found that this novel hybrid electrocatalyst exhibits excellent electrocatalytic properties and can be further applied in fuel cells, catalysts, and sensors. Copyright 2010 Elsevier Inc. All rights reserved.

  9. Preparation of AuPt alloy foam films and their superior electrocatalytic activity for the oxidation of formic acid.

    PubMed

    Liu, Jun; Cao, Ling; Huang, Wei; Li, Zelin

    2011-09-01

    AuPt alloy films with three-dimensional (3D) hierarchical pores consisting of interconnected dendrite walls were successfully fabricated by a strategy of cathodic codeposition utilizing the hydrogen bubble dynamic template. The foam films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Due to the special porous structure, the electronic property, and the assembly effect, the AuPt alloy foam films show superior electrocatalytic activity toward the electrooxidation of formic acid in acidic solution, and the prepared 3D porous AuPt alloy films also show high activity and long stability for the electrocatalytic oxidation of methanol, where synergistic effect plays an important role in addition to the electronic effect and assembly effect. These findings provide more insights into the AuPt bimetallic nanomaterials for electrocatalytic applications.

  10. Enhanced electroactivity of Pd nanocrystals supported on H3PMo12O40/carbon for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao; Zhu, Jianbing; Liang, Liang; Liu, Changpeng; Liao, Jianhui; Xing, Wei

    2012-07-01

    The preparation of highly dispersed precious metal catalysts is an important subject for fuel cell applications. Here, using a phosphomolybdic acid (PMo12)-assisted method, a Pd-PMo12/C catalyst with uniform Pd nanoparticles is prepared. The TEM results show that the presence of PMo12 facilitates the formation of uniform Pd particles with an average particle size of 3.2 nm. More importantly, the Pd-PMo12/C catalyst displays an enhanced activity and stability for formic acid electro-oxidation and a better tolerance toward CO poisoning than Pd nanocatalysts prepared with sodium citrate as a stabilizer. A combination of the composition and structure analyses show that the reasons for the improved electro-catalytic activity of the Pd-PMo12/C catalyst involve the metal-support interaction, the richer Pd oxide/hydrous oxide content and the inherent properties of PMo12.

  11. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Electro-oxidation of Formic Acid on Carbon Supported Edge-Truncated Cubic Platinum Nanoparticles Catalysts

    NASA Astrophysics Data System (ADS)

    Li, She-Qiang; Fu, Xing-Qiu; Hu, Bing; Deng, Jia-Jun; Chen, Lei

    2009-11-01

    The oxidation of formic acid on edge-truncated cubic platinum nanoparticles/C catalysts is investigated. X-ray photoelectron spectroscopy analysis indicates that the surface of edge-truncated cubic platinum nanoparticles is composed of two types of coordination sites. The oxidation behavior of formic acid on edge-truncated cubic platinum nanoparticles/C is investigated using cyclic voltammetry. The apparent activation energies are found to be 54.2, 55.0, 61.8, 69.5, 71.9, 69.26, 65.28kJ/mol at 0.15, 0.3, 0.4, 0.5, 0.6, 0.65, 0.7V, respectively. A specific surface area activity of 1.76 mA·cm-2 at 0.4 V indicates that the edge-truncated cubic Platinum nanoparticles are a promising anode catalyst for direct formic acid fuel cells.

  12. On the gas-particle partitioning of soluble organic aerosol in two urban atmospheres with contrasting emissions: 2. Gas and particle phase formic acid

    NASA Astrophysics Data System (ADS)

    Liu, Jiumeng; Zhang, Xiaolu; Parker, Eric T.; Veres, Patrick R.; Roberts, James M.; de Gouw, Joost A.; Hayes, Patrick L.; Jimenez, Jose L.; Murphy, Jennifer G.; Ellis, Raluca A.; Huey, L. Greg; Weber, Rodney J.

    2012-10-01

    Gas and fine particle (PM2.5) phase formic acid concentrations were measured with online instrumentation during separate one-month studies in the summer of 2010 in Los Angeles (LA), CA, and Atlanta, GA. In both urban environments, median gas phase concentrations were on the order of a few ppbv (LA 1.6 ppbv, Atlanta 2.3 ppbv) and median particle phase concentrations were approximately tens of ng/m3 (LA 49 ng/m3, Atlanta 39 ng/m3). LA formic acid gas and particle concentrations had consistent temporal patterns; both peaked in the early afternoon and generally followed the trends in photochemical secondary gases. Atlanta diurnal trends were more irregular, but the mean diurnal profile had similar afternoon peaks in both gas and particle concentrations, suggesting a photochemical source in both cities. LA formic acid particle/gas (p/g) ratios ranged between 0.01 and 12%, with a median of 1.3%. No clear evidence that LA formic acid preferentially partitioned to particle water was observed, except on three overcast periods of suppressed photochemical activity. Application of Henry's Law to predict partitioning during these periods greatly under-predicted particle phase formate concentrations based on bulk aerosol liquid water content (LWC) and pH estimated from thermodynamic models. In contrast to LA, formic acid partitioning in Atlanta appeared to be more consistently associated with elevated relative humidity (i.e., aerosol LWC), although p/g ratios were somewhat lower, ranging from 0.20 to 5.8%, with a median of 0.8%. Differences in formic acid gas absorbing phase preferences between these two cities are consistent with that of bulk water-soluble organic carbon reported in a companion paper.

  13. Facile synthesis of nitrogen-doped graphene supported AuPd-CeO2 nanocomposites with high-performance for hydrogen generation from formic acid at room temperature

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Li; Yan, Jun-Min; Zhang, Yue-Fei; Ping, Yun; Wang, Hong-Li; Jiang, Qing

    2014-02-01

    AuPd-CeO2 nanocomposites directly nucleated and grown on nitrogen-doped reduced graphene oxide, exhibit excellent catalytic activity and 100% hydrogen selectivity toward formic acid decomposition for hydrogen generation without any additives at room temperature.AuPd-CeO2 nanocomposites directly nucleated and grown on nitrogen-doped reduced graphene oxide, exhibit excellent catalytic activity and 100% hydrogen selectivity toward formic acid decomposition for hydrogen generation without any additives at room temperature. Electronic supplementary information (ESI) available: Experimental procedures; XPS, TEM, MS, GC, and EDX data; and the results of H2 generation from FA experiments. See DOI: 10.1039/c3nr05809c

  14. Bimetallic catalysts for CO.sub.2 hydrogenation and H.sub.2 generation from formic acid and/or salts thereof

    DOEpatents

    Hull, Jonathan F.; Himeda, Yuichiro; Fujita, Etsuko; Muckeman, James T.

    2015-08-04

    The invention relates to a ligand that may be used to create a catalyst including a coordination complex is formed by the addition of two metals; Cp, Cp* or an unsubstituted or substituted .pi.-arene; and two coordinating solvent species or solvent molecules. The bimetallic catalyst may be used in the hydrogenation of CO.sub.2 to form formic acid and/or salts thereof, and in the dehydrogenation of formic acid and/or salts thereof to form H.sub.2 and CO.sub.2.

  15. Nanoporous bimetallic Pt-Au alloy nanocomposites with superior catalytic activity towards electro-oxidation of methanol and formic acid.

    PubMed

    Zhang, Zhonghua; Wang, Yan; Wang, Xiaoguang

    2011-04-01

    We present a facile route to fabricate novel nanoporous bimetallic Pt-Au alloy nanocomposites by dealloying a rapidly solidified Al(75)Pt(15)Au(10) precursor under free corrosion conditions. The microstructure of the precursor and the as-dealloyed sample was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray (EDX) analysis. The Al(75)Pt(15)Au(10) precursor is composed of a single-phase Al(2)(Au,Pt) intermetallic compound, and can be fully dealloyed in a 20 wt.% NaOH or 5 wt.% HCl aqueous solution. The dealloying leads to the formation of the nanoporous Pt(60)Au(40) nanocomposites (np-Pt(60)Au(40) NCs) with an fcc structure. The morphology, size and crystal orientation of grains in the precursor can be conserved in the resultant nanoporous alloy. The np-Pt(60)Au(40) NCs consist of two zones with distinct ligament/channel sizes and compositions. The formation mechanism of these np-Pt(60)Au(40) NCs can be rationalized based upon surface diffusion of more noble elements and spinodal decomposition during dealloying. Electrochemical measurements demonstrate that the np-Pt(60)Au(40) NCs show superior catalytic activity towards the electro-oxidation of methanol and formic acid in the acid media compared to the commercial JM-Pt/C catalyst. This material can find potential applications in catalysis related areas, such as direct methanol or formic acid fuel cells. Our findings demonstrate that dealloying is an effective and simple strategy to realize the alloying of immiscible systems under mild conditions, and to fabricate novel nanostructures with superior performance.

  16. Formic acid catalyzed hydrolysis of SO3 in the gas phase: a barrierless mechanism for sulfuric acid production of potential atmospheric importance.

    PubMed

    Hazra, Montu K; Sinha, Amitabha

    2011-11-02

    Computational studies at the B3LYP/6-311++G(3df,3pd) and MP2/6-311++G(3df,3pd) levels are performed to explore the changes in reaction barrier height for the gas phase hydrolysis of SO(3) to form H(2)SO(4) in the presence of a single formic acid (FA) molecule. For comparison, we have also performed calculations for the reference reaction involving water assisted hydrolysis of SO(3) at the same level. Our results show that the FA assisted hydrolysis of SO(3) to form H(2)SO(4) is effectively a barrierless process. The barrier heights for the isomerization of the SO(3)···H(2)O···FA prereactive collision complex, which is the rate limiting step in the FA assisted hydrolysis, are found to be respectively 0.59 and 0.08 kcal/mol at the B3LYP/6-311++G(3df,3pd) and MP2/6-311++G(3df,3pd) levels. This is substantially lower than the ~7 kcal/mol barrier for the corresponding step in the hydrolysis of SO(3) by two water molecules--which is currently the accepted mechanism for atmospheric sulfuric acid production. Simple kinetic analysis of the relative rates suggests that the reduction in barrier height facilitated by FA, combined with the greater stability of the prereactive SO(3)···H(2)O···FA collision complex compared to SO(3)···H(2)O···H(2)O and the rather plentiful atmospheric abundance of FA, makes the formic acid mediated hydrolysis reaction a potentially important pathway for atmospheric sulfuric acid production.

  17. A facile one-pot synthesis and enhanced formic acid oxidation of monodisperse Pd-Cu nanocatalysts.

    PubMed

    Park, Kyu-Hwan; Lee, Young Wook; Kang, Shin Wook; Han, Sang Woo

    2011-06-06

    Highly monodisperse spherical 3 nm Pd-Cu alloy nanoparticles (NPs) were synthesized in high yield through the coreduction of [Pd(acac)(2)] (acac=acetylacetonate) and [Cu(acac)(2)] in nonhydrolytic solutions by using trioctylamine and oleic acid. The relative compositions of Pd and Cu could be tuned by controlling the molar ratios between the metal precursors in the raw solutions. The carbon-supported Pd-Cu NPs (Pd-Cu/C) were chemically dealloyed by acetic acid washing, which resulted in the formation of porous structures. The prepared Pd-Cu/C catalysts exhibited at least threefold enhancement of Pd mass activities compared with a commercial Pd/C catalyst toward formic acid oxidation in an acidic medium, and also showed outstanding electrocatalytic stabilities. The improved electrocatalytic properties of the Pd-Cu NPs are attributed to the presence of a large number of active sites on their surfaces owing to their small particle sizes and chemically dealloyed porous structures. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Assignment of the Perfluoropropionic Acid-Formic Acid Complex and the Difficulties of Including High K_a Transitions.

    NASA Astrophysics Data System (ADS)

    Obenchain, Daniel A.; Lin, Wei; Novick, Stewart E.; Cooke, S. A.

    2016-06-01

    We recently began an investigation into the perfluoropropionic acid\\cdotsformic acid complex using broadband microwave spectroscopy. This study aims to examine the possible double proton transfer between the two interacting carboxcyclic acid groups. The spectrum presented as a doubled set of lines, with spacing between transitions of < 1 MHz. Transitions appeared to be a-type, R branch transitions for an asymmetric top. Assignment of all K_a=1,0 transitions yields decent fits to a standard rotational Hamiltonian. Treatment of the doubling as either a two state system (presumably with a double proton transfer) or as two distinct, but nearly identical conformations of the complex produce fits of similar quality. Including higher K_a transitions for the a-type, R-branch lines greatly increases the error of these fits. A previous study involving the trifluoroacetic acid\\cdotsformic acid complex published observed similar high K_a transitions, but did not include them in the published fit. We hope to shed more light on this conundrum. Similarities to other double-well potential minimum systems will be discussed. Martinache, L.; Kresa, W.; Wegener, M.;, Vonmont, U.; and Bauder, A. Chem. Phys. 148 (1990) 129-140.

  19. Challenges in the Greener Production of Formates/Formic Acid, Methanol, and DME by Heterogeneously Catalyzed CO2 Hydrogenation Processes

    PubMed Central

    2017-01-01

    The recent advances in the development of heterogeneous catalysts and processes for the direct hydrogenation of CO2 to formate/formic acid, methanol, and dimethyl ether are thoroughly reviewed, with special emphasis on thermodynamics and catalyst design considerations. After introducing the main motivation for the development of such processes, we first summarize the most important aspects of CO2 capture and green routes to produce H2. Once the scene in terms of feedstocks is introduced, we carefully summarize the state of the art in the development of heterogeneous catalysts for these important hydrogenation reactions. Finally, in an attempt to give an order of magnitude regarding CO2 valorization, we critically assess economical aspects of the production of methanol and DME and outline future research and development directions. PMID:28656757

  20. Complementary cavity-enhanced spectrometers to investigate the OH + CH combination band in trans-formic acid.

    PubMed

    Golebiowski, D; Földes, T; Vanfleteren, T; Herman, M; Perrin, A

    2015-07-07

    We have used continuous-wave cavity ring-down and femto-Fourier transform-cavity-enhanced absorption spectrometers to record the spectrum of the OH-stretching + CH-stretching (ν1 + ν2) combination band in trans-formic acid, with origin close to 6507 cm(-1). They, respectively, allowed resolving and simplifying the rotational structure of the band near its origin under jet-cooled conditions (Trot = 10 K) and highlighting the overview of the band under room temperature conditions. The stronger B-type and weaker A-type subbands close to the band origin could be assigned, as well as the main B-type Q branches. The high-resolution analysis was hindered by numerous, severe perturbations. Rotational constants are reported with, however, limited physical meaning. The ν1 + ν2 transition moment is estimated from relative intensities to be 24° away from the principal b-axis of inertia.

  1. Chemistry of OH in remote clouds and its role in the production of formic acid and peroxymonosulfate

    NASA Technical Reports Server (NTRS)

    Jacob, D. J.

    1986-01-01

    The chemistry of OH in nonprecipitating tropospheric clouds was studied using a coupled gas phase/aqueous phase chemical model. The simulation takes into account the radial dependence of the concentrations of short lived aqueous phase species, in particular, O3(aq) OH(aq). Formic acid is shown to be rapidly produced by the aqueous phase reaction between H2C(OH)2 and OH, but HCOO(-) and OH, but HCOO(-) is in turn rapidly oxidized by OH(aq). The HCOOH concentration in cloud is shown to be strongly dependent on the pH of the cloud water; clouds with pH greater than 5 are not efficient HCOOH sources. A novel mechanism is proposed for the oxidation of S(IV) by OH(aq), with the main product predicted to be peroxymonosulfate, HSO5(-). The latter could contribute significantly to total cloud water sulfur.

  2. Microwave spectrum and molecular structure parameters for the 1,2-cyclohexanedione (monoenolic)-formic acid dimer

    NASA Astrophysics Data System (ADS)

    Pejlovas, Aaron M.; Barfield, Michael; Kukolich, Stephen G.

    2014-10-01

    The microwave spectrum for the 1,2-cyclohexanedione (monoenolic)-formic acid dimer was measured for four isotopologues in the 4.5-9 GHz range using a Flygare-Balle type spectrometer. Rotational and distortion constants (A, B, C, DJ, DJK) were obtained. Measured rotational constants were used in a least squares fit to determine some of the gas phase structural parameters of the dimer. Rotational constants and distortion constants of the parent isotopologue are A = 2415.044(18) MHz, B = 543.6907(2) MHz, C = 451.6663(2) MHz, DJ = 0.0220(13) kHz, and DJK = 0.119(31) kHz. The experimental hydrogen bond lengths are 1.97 Å, somewhat longer than the values calculated using GAUSSIAN 09 with MP2/6-311++G**.

  3. Nanobranched porous palladium-tin intermetallics: One-step synthesis and their superior electrocatalysis towards formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Sun, Dandan; Si, Ling; Fu, Gengtao; Liu, Chang; Sun, Dongmei; Chen, Yu; Tang, Yawen; Lu, Tianhong

    2015-04-01

    Nanocrystalline intermetallics in bulk with high surface area hold enormous promise as an efficient catalyst for real fuel cell applications due to their unique electrocatalytic properties. In this work, a novel three-dimensional (3D) porous Pd-Sn intermetallics in network nanostructures (Pd-Sn-INNs) has been fabricated at relatively low temperature for the first time by one-step ethylene glycol-assisted hydrothermal reduction method. The structure characteristics of the Pd-Sn-INNs are confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The as-prepared 3D Pd-Sn-INNs exhibit remarkably improved electrocatalytic activity and stability towards formic acid oxidation reaction (FAOR) over commercially available Pd black.

  4. Graphene nanosheets-polypyrrole hybrid material as a highly active catalyst support for formic acid electro-oxidation.

    PubMed

    Yang, Sudong; Shen, Chengmin; Liang, Yanyu; Tong, Hao; He, Wei; Shi, Xuezhao; Zhang, Xiaogang; Gao, Hong-jun

    2011-08-01

    A novel electrode material based on graphene oxide (GO)-polypyrrole (PPy) composites was synthesized by in situ chemical oxidation polymerization. Palladium nanoparticles (NPs) with a diameter of 4.0 nm were loaded on the reduced graphene oxide(RGO)-PPy composites by a microwave-assisted polyol process. Microstructure analysis showed that a layer of coated PPy film with monodisperse Pd NPs is present on the RGO surface. The Pd/RGO-PPy catalysts exhibit excellent catalytic activity and stability for formic acid electro-oxidation when the weight feed ratio of GO to pyrrole monomer is 2:1. The superior performance of Pd/RGO-PPy catalysts may arise from utilization of heterogeneous nucleation sites for NPs and the greatly increased electronic conductivity of the supports. This journal is © The Royal Society of Chemistry 2011

  5. Synthesis of Ultrathin PdCu Alloy Nanosheets Used as a Highly Efficient Electrocatalyst for Formic Acid Oxidation.

    PubMed

    Yang, Nailiang; Zhang, Zhicheng; Chen, Bo; Huang, Ying; Chen, Junze; Lai, Zhuangchai; Chen, Ye; Sindoro, Melinda; Wang, An-Liang; Cheng, Hongfei; Fan, Zhanxi; Liu, Xiaozhi; Li, Bing; Zong, Yun; Gu, Lin; Zhang, Hua

    2017-08-01

    Inspired by the unique properties of ultrathin 2D nanomaterials and excellent catalytic activities of noble metal nanostructures for renewable fuel cells, a facile method is reported for the high-yield synthesis of ultrathin 2D PdCu alloy nanosheets under mild conditions. Impressively, the obtained PdCu alloy nanosheet after being treated with ethylenediamine can be used as a highly efficient electrocatalyst for formic acid oxidation. The study implicates that the rational design and controlled synthesis of an ultrathin 2D noble metal alloy may open up new opportunities for enhancing catalytic activities of noble metal nanostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Polyhedral Palladium-Silver Alloy Nanocrystals as Highly Active and Stable Electrocatalysts for the Formic Acid Oxidation Reaction

    NASA Astrophysics Data System (ADS)

    Fu, Geng-Tao; Liu, Chang; Zhang, Qi; Chen, Yu; Tang, Ya-Wen

    2015-09-01

    Polyhedral noble-metal nanocrystals have received much attention and wide applications as electrical and optical devices as well as catalysts. In this work, a straightforward and effective hydrothermal route for the controllable synthesis of the high-quality Pd-Ag alloy polyhedrons with uniform size is presented. The morphology, composition and structure of the Pd-Ag alloy polyhedrons are fully characterized by the various physical techniques, demonstrating the Pd-Ag alloy polyhedrons are highly alloying. The formation/growth mechanisms of the Pd-Ag alloy polyhedrons are explored and discussed based on the experimental observations and discussions. As a preliminary electrochemical application, the Pd-Ag alloy polyhedrons are applied in the formic acid oxidation reaction, which shows higher electrocatalytic activity and stability than commercially available Pd black due to the “synergistic effects” between Pd and Ag atoms.

  7. Preparation of Nanoporous Pd by Dealloying Al-Pd Slice and Its Electrocatalysts for Formic Acid Oxidation

    NASA Astrophysics Data System (ADS)

    Yu, Nana; Wang, Tianning; Nie, Chen; Sun, Lanju; Li, Jie; Geng, Haoran

    2016-01-01

    AlPd alloy slices with a thickness of 0.5 mm were taken as precursors during the fabrication of nanoporous palladium (np-Pd) using chemical dealloying in NaOH solution or electrochemical dealloying in NaCl solution. Scanning electron microscope photos and x-ray diffraction patterns demonstrate a full dealloying of Al out of the precursors and the formation of nP-Pd which is characterized by a three-dimensional, bicontinuous, ligament-channel structure with nanoscale length scales. Electrochemical measurements were performed to evaluate the electrocatalytic activity and structure stability of np-Pd towards formic acid oxidation and it showed a good structure stability.

  8. Polyhedral Palladium-Silver Alloy Nanocrystals as Highly Active and Stable Electrocatalysts for the Formic Acid Oxidation Reaction.

    PubMed

    Fu, Geng-Tao; Liu, Chang; Zhang, Qi; Chen, Yu; Tang, Ya-Wen

    2015-09-02

    Polyhedral noble-metal nanocrystals have received much attention and wide applications as electrical and optical devices as well as catalysts. In this work, a straightforward and effective hydrothermal route for the controllable synthesis of the high-quality Pd-Ag alloy polyhedrons with uniform size is presented. The morphology, composition and structure of the Pd-Ag alloy polyhedrons are fully characterized by the various physical techniques, demonstrating the Pd-Ag alloy polyhedrons are highly alloying. The formation/growth mechanisms of the Pd-Ag alloy polyhedrons are explored and discussed based on the experimental observations and discussions. As a preliminary electrochemical application, the Pd-Ag alloy polyhedrons are applied in the formic acid oxidation reaction, which shows higher electrocatalytic activity and stability than commercially available Pd black due to the "synergistic effects" between Pd and Ag atoms.

  9. Synthesis of cubic and spherical Pd nanoparticles on graphene and their electrocatalytic performance in the oxidation of formic acid.

    PubMed

    Yang, Sudong; Shen, Chengmin; Tian, Yuan; Zhang, Xiaogang; Gao, Hong-Jun

    2014-11-07

    Single-crystal palladium nanoparticles (NPs) with controllable morphology were synthesized on the surface of reduced graphene oxide (RGO) by a novel procedure, namely reducing palladium acetylacetonate [Pd(acac)2] with the N-methylpyrrolidone (NMP) solvent in the presence of poly(vinylpyrrolidone) (PVP). The resulting Pd nanocrystals (8 nm in diameter) were uniformly distributed on the RGO. A possible formation mechanism is discussed. The electrocatalytic performance of Pd nanocrystal/RGO catalysts during formic acid oxidation was investigated, which revealed that the cubic Pd/RGO catalyst performed significantly better than the spherical Pd/RGO catalyst. The shape of Pd nanocrystals on the surface of graphene nanosheets can be easily controlled via tuning the synthesis parameters, resulting in tunable catalytic properties. Moreover, this method can be easily extended to fabricate other noble metal nanostructures.

  10. Graphene nanosheets-polypyrrole hybrid material as a highly active catalyst support for formic acid electro-oxidation

    NASA Astrophysics Data System (ADS)

    Yang, Sudong; Shen, Chengmin; Liang, Yanyu; Tong, Hao; He, Wei; Shi, Xuezhao; Zhang, Xiaogang; Gao, Hong-Jun

    2011-08-01

    A novel electrode material based on graphene oxide (GO)-polypyrrole (PPy) composites was synthesized by in situ chemical oxidation polymerization. Palladium nanoparticles (NPs) with a diameter of 4.0 nm were loaded on the reduced graphene oxide(RGO)-PPy composites by a microwave-assisted polyol process. Microstructure analysis showed that a layer of coated PPy film with monodisperse Pd NPs is present on the RGO surface. The Pd/RGO-PPy catalysts exhibit excellent catalytic activity and stability for formic acid electro-oxidation when the weight feed ratio of GO to pyrrole monomer is 2 : 1. The superior performance of Pd/RGO-PPy catalysts may arise from utilization of heterogeneous nucleation sites for NPs and the greatly increased electronic conductivity of the supports.

  11. Synthesis of cubic and spherical Pd nanoparticles on graphene and their electrocatalytic performance in the oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Yang, Sudong; Shen, Chengmin; Tian, Yuan; Zhang, Xiaogang; Gao, Hong-Jun

    2014-10-01

    Single-crystal palladium nanoparticles (NPs) with controllable morphology were synthesized on the surface of reduced graphene oxide (RGO) by a novel procedure, namely reducing palladium acetylacetonate [Pd(acac)2] with the N-methylpyrrolidone (NMP) solvent in the presence of poly(vinylpyrrolidone) (PVP). The resulting Pd nanocrystals (8 nm in diameter) were uniformly distributed on the RGO. A possible formation mechanism is discussed. The electrocatalytic performance of Pd nanocrystal/RGO catalysts during formic acid oxidation was investigated, which revealed that the cubic Pd/RGO catalyst performed significantly better than the spherical Pd/RGO catalyst. The shape of Pd nanocrystals on the surface of graphene nanosheets can be easily controlled via tuning the synthesis parameters, resulting in tunable catalytic properties. Moreover, this method can be easily extended to fabricate other noble metal nanostructures.

  12. A facile route to monodisperse MPd (M = Co or Cu) alloy nanoparticles and their catalysis for electrooxidation of formic acid.

    PubMed

    Ho, Sally Fae; Mendoza-Garcia, Adriana; Guo, Shaojun; He, Kai; Su, Dong; Liu, Sheng; Metin, Önder; Sun, Shouheng

    2014-06-21

    MPd (M = Co, or Cu) nanoparticles (NPs) were synthesized by borane-amine reduction of metal acetylacetonates. The size of the MPd NPs was controlled at 3.5 nm and their compositions were tuned by the molar ratios of the metal precursors. These MPd NPs were active catalysts for electrochemical oxidation of formic acid and the Cu30Pd70 NPs showed the highest mass activity at 1192.9 A gPd(-1), much higher than 552.6 A gPd(-1) obtained from the 3.5 nm Pd NPs. Our synthesis provides a facile route to MPd NPs, allowing further investigation of MPd NP catalysts for electrochemical oxidation and many other chemical reactions.

  13. Polyhedral Palladium–Silver Alloy Nanocrystals as Highly Active and Stable Electrocatalysts for the Formic Acid Oxidation Reaction

    PubMed Central

    Fu, Geng-Tao; Liu, Chang; Zhang, Qi; Chen, Yu; Tang, Ya-Wen

    2015-01-01

    Polyhedral noble–metal nanocrystals have received much attention and wide applications as electrical and optical devices as well as catalysts. In this work, a straightforward and effective hydrothermal route for the controllable synthesis of the high-quality Pd–Ag alloy polyhedrons with uniform size is presented. The morphology, composition and structure of the Pd–Ag alloy polyhedrons are fully characterized by the various physical techniques, demonstrating the Pd–Ag alloy polyhedrons are highly alloying. The formation/growth mechanisms of the Pd–Ag alloy polyhedrons are explored and discussed based on the experimental observations and discussions. As a preliminary electrochemical application, the Pd–Ag alloy polyhedrons are applied in the formic acid oxidation reaction, which shows higher electrocatalytic activity and stability than commercially available Pd black due to the “synergistic effects” between Pd and Ag atoms. PMID:26329555

  14. A photocatalyst-enzyme coupled artificial photosynthesis system for solar energy in production of formic acid from CO2.

    PubMed

    Yadav, Rajesh K; Baeg, Jin-Ook; Oh, Gyu Hwan; Park, No-Joong; Kong, Ki-jeong; Kim, Jinheung; Hwang, Dong Won; Biswas, Soumya K

    2012-07-18

    The photocatalyst-enzyme coupled system for artificial photosynthesis process is one of the most promising methods of solar energy conversion for the synthesis of organic chemicals or fuel. Here we report the synthesis of a novel graphene-based visible light active photocatalyst which covalently bonded the chromophore, such as multianthraquinone substituted porphyrin with the chemically converted graphene as a photocatalyst of the artificial photosynthesis system for an efficient photosynthetic production of formic acid from CO(2). The results not only show a benchmark example of the graphene-based material used as a photocatalyst in general artificial photosynthesis but also the benchmark example of the selective production system of solar chemicals/solar fuel directly from CO(2).

  15. Nanoporous bimetallic Pt-Au alloy nanocomposites with superior catalytic activity towards electro-oxidation of methanol and formic acid

    NASA Astrophysics Data System (ADS)

    Zhang, Zhonghua; Wang, Yan; Wang, Xiaoguang

    2011-04-01

    We present a facile route to fabricate novel nanoporous bimetallic Pt-Au alloy nanocomposites by dealloying a rapidly solidified Al75Pt15Au10 precursor under free corrosion conditions. The microstructure of the precursor and the as-dealloyed sample was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray (EDX) analysis. The Al75Pt15Au10 precursor is composed of a single-phase Al2(Au,Pt) intermetallic compound, and can be fully dealloyed in a 20 wt.% NaOH or 5 wt.% HCl aqueous solution. The dealloying leads to the formation of the nanoporous Pt60Au40 nanocomposites (np-Pt60Au40 NCs) with an fcc structure. The morphology, size and crystal orientation of grains in the precursor can be conserved in the resultant nanoporous alloy. The np-Pt60Au40 NCs consist of two zones with distinct ligament/channel sizes and compositions. The formation mechanism of these np-Pt60Au40 NCs can be rationalized based upon surface diffusion of more noble elements and spinodal decomposition during dealloying. Electrochemical measurements demonstrate that the np-Pt60Au40 NCs show superior catalytic activity towards the electro-oxidation of methanol and formic acid in the acid media compared to the commercial JM-Pt/C catalyst. This material can find potential applications in catalysis related areas, such as direct methanol or formic acidfuelcells. Our findings demonstrate that dealloying is an effective and simple strategy to realize the alloying of immiscible systems under mild conditions, and to fabricate novel nanostructures with superior performance.We present a facile route to fabricate novel nanoporous bimetallic Pt-Au alloy nanocomposites by dealloying a rapidly solidified Al75Pt15Au10 precursor under free corrosion conditions. The microstructure of the precursor and the as-dealloyed sample was characterized using X-ray diffraction, scanning electron

  16. The Melting Curve and High-Pressure Chemistry of Formic Acid to 8 GPa and 600 K

    SciTech Connect

    Montgomery, W; Zaug, J M; Howard, W M; Goncharov, A F; Crowhurst, J C; Jeanloz, R

    2005-04-13

    We have determined the melting temperature of formic acid (HCOOH) to 8.5 GPa using infrared absorption spectroscopy, Raman spectroscopy and visual observation of samples in a resistively heated diamond-anvil cell. The experimentally determined melting curve compares favorably with a two-phase thermodynamic model. Decomposition reactions were observed above the melting temperature up to a pressure of 6.5 GPa, where principal products were CO{sub 2}, H{sub 2}O and CO. At pressures above 6.5 GPa, decomposition led to solid-like reaction products. Infrared and Raman spectra of these recovered products indicate that pressure affects the nature of carbon-carbon bonding.

  17. A Comprehensive Study of Formic Acid Oxidation on Palladium Nanocrystals with Different Types of Facets and Twin Defects

    SciTech Connect

    Choi, Sang; Herron, Jeffrey A.; Scaranto, Jessica; Huang, Hongwen; Wang, Yi; Xia, Xiaohu; Lv, Tian; Park, Jinho; Peng, Hsin-Chieh; Mavrikakis, Manos; Xia, Younan

    2015-07-13

    Palladium has been recognized as the best anodic, monometallic electrocatalyst for the formic acid oxidation (FAO) reaction in a direct formic acid fuel cell. Here we report a systematic study of FAO on a variety of Pd nanocrystals, including cubes, right bipyramids, octahedra, tetrahedra, decahedra, and icosahedra. These nanocrystals were synthesized with approximately the same size, but different types of facets and twin defects on their surfaces. Our measurements indicate that the Pd nanocrystals enclosed by {1 0 0} facets have higher specific activities than those enclosed by {1 1 1} facets, in agreement with prior observations for Pd single-crystal substrates. If comparing nanocrystals predominantly enclosed by a specific type of facet, {1 0 0} or {1 1 1}, those with twin defects displayed greatly enhanced FAO activities compared to their single-crystal counterparts. To rationalize these experimental results, we performed periodic, self-consistent DFT calculations on model single-crystal substrates of Pd, representing the active sites present in the nanocrystals used in the experiments. The calculation results suggest that the enhancement of FAO activity on defect regions, represented by Pd(2 1 1) sites, compared to the activity of both Pd(1 0 0) and Pd(1 1 1) surfaces, could be attributed to an increased flux through the HCOO-mediated pathway rather than the COOH-mediated pathway on Pd(2 1 1). Since COOH has been identified as a precursor to CO, a site-poisoning species, a lower coverage of CO at the defect regions will lead to a higher activity for the corresponding nanocrystal catalysts, containing those defect regions.

  18. A facile route to monodisperse MPd (M = Co or Cu) alloy nanoparticles and their catalysis for electrooxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Ho, Sally Fae; Mendoza-Garcia, Adriana; Guo, Shaojun; He, Kai; Su, Dong; Liu, Sheng; Metin, Önder; Sun, Shouheng

    2014-05-01

    MPd (M = Co, or Cu) nanoparticles (NPs) were synthesized by borane-amine reduction of metal acetylacetonates. The size of the MPd NPs was controlled at 3.5 nm and their compositions were tuned by the molar ratios of the metal precursors. These MPd NPs were active catalysts for electrochemical oxidation of formic acid and the Cu30Pd70 NPs showed the highest mass activity at 1192.9 A gPd-1, much higher than 552.6 A gPd-1 obtained from the 3.5 nm Pd NPs. Our synthesis provides a facile route to MPd NPs, allowing further investigation of MPd NP catalysts for electrochemical oxidation and many other chemical reactions.MPd (M = Co, or Cu) nanoparticles (NPs) were synthesized by borane-amine reduction of metal acetylacetonates. The size of the MPd NPs was controlled at 3.5 nm and their compositions were tuned by the molar ratios of the metal precursors. These MPd NPs were active catalysts for electrochemical oxidation of formic acid and the Cu30Pd70 NPs showed the highest mass activity at 1192.9 A gPd-1, much higher than 552.6 A gPd-1 obtained from the 3.5 nm Pd NPs. Our synthesis provides a facile route to MPd NPs, allowing further investigation of MPd NP catalysts for electrochemical oxidation and many other chemical reactions. Electronic supplementary information (ESI) available: Detailed synthetic and electrochemical analysis procedures, and XRD of the NPs. See DOI: 10.1039/c4nr01107d

  19. Mg(2+)-assisted low temperature reduction of alloyed AuPd/C: an efficient catalyst for hydrogen generation from formic acid at room temperature.

    PubMed

    Wu, Shuang; Yang, Fan; Wang, Hao; Chen, Rui; Sun, Pingchuan; Chen, Tiehong

    2015-07-11

    The Mg(2+)-assisted low temperature reduction approach was applied for the preparation of an alloyed AuPd/C nanocatalyst, which exhibited high activity in hydrogen generation from formic acid. At room temperature the initial turnover frequency (TOF) could reach as high as 1120 h(-1).

  20. Continuous-flow hydrogenation of carbon dioxide to pure formic acid using an integrated scCO2 process with immobilized catalyst and base.

    PubMed

    Wesselbaum, Sebastian; Hintermair, Ulrich; Leitner, Walter

    2012-08-20

    Dual role for CO(2): Pure formic acid can be obtained continuously by hydrogenation of CO(2) in a single processing unit. An immobilized ruthenium organometallic catalyst and a nonvolatile base in an ionic liquid (IL) are combined with supercritical CO(2) as both reactant and extractive phase.

  1. Tropospheric Emission Spectrometer (TES) satellite observations of ammonia, methanol, formic acid, and carbon monoxide over the Canadian oil sands: validation and model evaluation

    EPA Science Inventory

    The wealth of air quality information provided by satellite infrared observations of ammonia (NH3), carbon monoxide (CO), formic acid (HCOOH), and methanol (CH3OH) is currently being explored and used for a number of applications, especially at regional or global scales. These ap...

  2. Facile one-pot surfactant-free synthesis of uniform Pd6Co nanocrystals on 3D graphene as an efficient electrocatalyst toward formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Lian Ying; Zhao, Zhi Liang; Yuan, Weiyong; Li, Chang Ming

    2016-01-01

    Ultrasmall and uniform Pd6Co nanocrystals were deposited on 3D graphene by a facile one-pot surfactant-free route for a catalyst toward formic acid oxidation, showing a much higher electrocatalytic activity, larger peak current density and better stability than Pd/3DG, Pd/C as well as commercial Pd-C, and thus offering great potential for an efficient anode catalyst toward high performance direct formic acid fuel cells.Ultrasmall and uniform Pd6Co nanocrystals were deposited on 3D graphene by a facile one-pot surfactant-free route for a catalyst toward formic acid oxidation, showing a much higher electrocatalytic activity, larger peak current density and better stability than Pd/3DG, Pd/C as well as commercial Pd-C, and thus offering great potential for an efficient anode catalyst toward high performance direct formic acid fuel cells. Electronic supplementary information (ESI) available: Experimental section and supplementary figures. See DOI: 10.1039/c5nr08512h

  3. Ru-assisted synthesis of {111}-faceted Pd truncated bipyramids: a highly reactive, stable and restorable catalyst for formic acid oxidation.

    PubMed

    Wu, Dongshuang; Cao, Minna; Cao, Rong

    2014-11-04

    {111}-Faceted Pd truncated triangular bipyramids (TTBPs) are first presented under the assistance of Ru. Attributed to their unique shape, the TTBPs are highly active and stable for formic acid oxidation. The electrochemical active surface area (ECSA) can be restored to its initial value after a harsh degradation test.

  4. Ternary Pd-Ni-P hybrid electrocatalysts derived from Pd-Ni core-shell nanoparticles with enhanced formic acid oxidation activity.

    PubMed

    Liang, Xin; Liu, Bo; Zhang, Juntao; Lu, Siqi; Zhuang, Zhongbin

    2016-09-25

    Ternary Pd-Ni-P hybrid electrocatalysts were synthesized through low temperature phosphidation of Pd-Ni core-shell nanoparticles. They show enhanced formic acid electro-oxidation activity compared to Pd, Pd-Ni and Pd-P nanoparticles, which is ascribed to the synergistic effect of the Ni and P components with Pd.

  5. Tropospheric Emission Spectrometer (TES) satellite observations of ammonia, methanol, formic acid, and carbon monoxide over the Canadian oil sands: validation and model evaluation

    EPA Science Inventory

    The wealth of air quality information provided by satellite infrared observations of ammonia (NH3), carbon monoxide (CO), formic acid (HCOOH), and methanol (CH3OH) is currently being explored and used for a number of applications, especially at regional or global scales. These ap...

  6. Ultrafast synthesis of flower-like ordered Pd3Pb nanocrystals with superior electrocatalytic activities towards oxidation of formic acid and ethanol

    NASA Astrophysics Data System (ADS)

    Jana, Rajkumar; Subbarao, Udumula; Peter, Sebastian C.

    2016-01-01

    Ordered intermetallic nanocrystals with high surface area are highly promising as efficient catalysts for fuel cell applications because of their unique electrocatalytic properties. The present work discusses about the controlled synthesis of ordered intermetallic Pd3Pb nanocrystals in different morphologies at relatively low temperature for the first time by polyol and hydrothermal methods both in presence and absence of surfactant. Here for the first time we report surfactant free synthesis of ordered flower-like intermetallic Pd3Pb nanocrystals in 10 s. The structural characteristics of the nanocrystals are confirmed by powder X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The as synthesized ordered Pd3Pb nanocrystals exhibit far superior electrocatalytic activity and durability towards formic acid and ethanol oxidation over commercially available Pd black (Pd/C). The morphological variation of nanocrystals plays a crucial role in the electrocatalytic oxidation of formic acid and ethanol. Among the catalysts, the flower-like Pd3Pb shows enhanced activity and stability in electrocatalytic formic acid and ethanol oxidation. The current density and mass activity of flower-like Pd3Pb catalyst are higher by 2.5 and 2.4 times than that of Pd/C for the formic acid oxidation and 1.5 times each for ethanol oxidation.

  7. Phenylamine-functionalized mesoporous silica supported PdAg nanoparticles: a dual heterogeneous catalyst for formic acid/CO2-mediated chemical hydrogen delivery/storage.

    PubMed

    Mori, Kohsuke; Masuda, Shinya; Tanaka, Hiromasa; Yoshizawa, Kazunari; Che, Michel; Yamashita, Hiromi

    2017-04-25

    A PdAg-based nanoparticle catalyst supported on the mesoporous silica material, SBA-15, modified with a weakly basic phenylamine functional group has been developed as a dual heterogeneous catalyst for the H2 delivery and H2 storage reactions mediated by formic acid and carbon dioxide.

  8. Analytical continuation in coupling constant method; application to the calculation of resonance energies and widths for organic molecules: Glycine, alanine and valine and dimer of formic acid

    NASA Astrophysics Data System (ADS)

    Papp, P.; Matejčík, Š.; Mach, P.; Urban, J.; Paidarová, I.; Horáček, J.

    2013-06-01

    The method of analytic continuation in the coupling constant (ACCC) in combination with use of the statistical Padé approximation is applied to the determination of resonance energy and width of some amino acids and formic acid dimer. Standard quantum chemistry codes provide accurate data which can be used for analytic continuation in the coupling constant to obtain the resonance energy and width of organic molecules with a good accuracy. The obtained results are compared with the existing experimental ones.

  9. Large-Scale Distributions of Tropospheric Nitric, Formic, and Acetic acids Over the Westerm Pacific Basin During Wintertime

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Dibb, J. E.; Lefer, B. L.; Scheuer, E. M.; Bradshaw, J. D.; Sandholm, S. T.; Smyth, S.; Blake, D. R.; Blake, N. J.; Sachse, G. W.; hide

    1997-01-01

    We report here measurements of the acidic gases nitric (HNO3), formic (HCOOH), and acetic (CH3COOH) over the western Pacific basin during the February-March 1994 Pacific Exploratory Mission-West (PEM-West B). These data were obtained aboard the NASA DC-8 research aircraft as it flew missions in the altitude range of 0.3 - 12.5 km over equatorial regions near Guam and then further westward encompassing the entire Pacific Rim arc. Aged marine air over the equatorial Pacific generally exhibited mixing ratios of acidic gases less than 100 parts per trillion by volume (pptv). Near the Asian continent, discrete plumes encountered below 6 km altitude contained up to 8 parts per billion by volume (ppbv) HNO3 and 10 ppbv HCOOH and CH3COOH. Overall there was a general correlation between mixing ratios of acidic gases with those of CO, C2H2, and C2Cl4, indicative of emissions from combustion and industrial sources. The latitudinal distributions of HNO3 and CO showed that the largest mixing ratios were centered around 15 deg N, while HCOOH, CH3COOH, and C2Cl4 peaked at 25 deg N. The mixing ratios of HCOOH and CH3COOH were highly correlated (r(sup 2) = 0.87) below 6 km altitude, with a slope (0.89) characteristic of the nongrowing season at midlatitudes in the northern hemisphere. Above 6 km altitude, HCOOH and CH3COOH were marginally correlated (r(sup 2) = 0.50), and plumes well defined by CO, C2H2, and C2Cl4 were depleted in acidic gases, most likely due to scavenging during vertical transport of air masses through convective cloud systems over the Asian continent. In stratospheric air masses, HNO, mixing ratios were several parts per billion by volume (ppbv), yielding relationships with 03 and N2O consistent with those previously reported for NO(y).

  10. Large-Scale Distributions of Tropospheric Nitric, Formic, and Acetic acids Over the Westerm Pacific Basin During Wintertime

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Dibb, J. E.; Lefer, B. L.; Scheuer, E. M.; Bradshaw, J. D.; Sandholm, S. T.; Smyth, S.; Blake, D. R.; Blake, N. J.; Sachse, G. W.; Collins, J. E.; Gregory, G. L.

    1997-01-01

    We report here measurements of the acidic gases nitric (HNO3), formic (HCOOH), and acetic (CH3COOH) over the western Pacific basin during the February-March 1994 Pacific Exploratory Mission-West (PEM-West B). These data were obtained aboard the NASA DC-8 research aircraft as it flew missions in the altitude range of 0.3 - 12.5 km over equatorial regions near Guam and then further westward encompassing the entire Pacific Rim arc. Aged marine air over the equatorial Pacific generally exhibited mixing ratios of acidic gases less than 100 parts per trillion by volume (pptv). Near the Asian continent, discrete plumes encountered below 6 km altitude contained up to 8 parts per billion by volume (ppbv) HNO3 and 10 ppbv HCOOH and CH3COOH. Overall there was a general correlation between mixing ratios of acidic gases with those of CO, C2H2, and C2Cl4, indicative of emissions from combustion and industrial sources. The latitudinal distributions of HNO3 and CO showed that the largest mixing ratios were centered around 15 deg N, while HCOOH, CH3COOH, and C2Cl4 peaked at 25 deg N. The mixing ratios of HCOOH and CH3COOH were highly correlated (r(sup 2) = 0.87) below 6 km altitude, with a slope (0.89) characteristic of the nongrowing season at midlatitudes in the northern hemisphere. Above 6 km altitude, HCOOH and CH3COOH were marginally correlated (r(sup 2) = 0.50), and plumes well defined by CO, C2H2, and C2Cl4 were depleted in acidic gases, most likely due to scavenging during vertical transport of air masses through convective cloud systems over the Asian continent. In stratospheric air masses, HNO, mixing ratios were several parts per billion by volume (ppbv), yielding relationships with 03 and N2O consistent with those previously reported for NO(y).

  11. 3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid.

    PubMed

    Assaud, Loïc; Monyoncho, Evans; Pitzschel, Kristina; Allagui, Anis; Petit, Matthieu; Hanbücken, Margrit; Baranova, Elena A; Santinacci, Lionel

    2014-01-01

    Three-dimensionally (3D) nanoarchitectured palladium/nickel (Pd/Ni) catalysts, which were prepared by atomic layer deposition (ALD) on high-aspect-ratio nanoporous alumina templates are investigated with regard to the electrooxidation of formic acid in an acidic medium (0.5 M H2SO4). Both deposition processes, Ni and Pd, with various mass content ratios have been continuously monitored by using a quartz crystal microbalance. The morphology of the Pd/Ni systems has been studied by electron microscopy and shows a homogeneous deposition of granularly structured Pd onto the Ni substrate. X-ray diffraction analysis performed on Ni and NiO substrates revealed an amorphous structure, while the Pd coating crystallized into a fcc lattice with a preferential orientation along the [220]-direction. Surface chemistry analysis by X-ray photoelectron spectroscopy showed both metallic and oxide contributions for the Ni and Pd deposits. Cyclic voltammetry of the Pd/Ni nanocatalysts revealed that the electrooxidation of HCOOH proceeds through the direct dehydrogenation mechanism with the formation of active intermediates. High catalytic activities are measured for low masses of Pd coatings that were generated by a low number of ALD cycles, probably because of the cluster size effect, electronic interactions between Pd and Ni, or diffusion effects.

  12. Biosorption of formic and acetic acids from aqueous solution using activated carbon from shea butter seed shells

    NASA Astrophysics Data System (ADS)

    Adekola, Folahan A.; Oba, Ismaila A.

    2016-10-01

    The efficiency of prepared activated carbon from shea butter seed shells (SB-AC) for the adsorption of formic acid (FA) and acetic acid (AA) from aqueous solution was investigated. The effect of optimization parameters including initial concentration, agitation time, adsorbent dosage and temperature of adsorbate solution on the sorption capacity were studied. The SB-AC was characterized for the following parameters: bulk density, moisture content, ash content, pH, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optimal conditions for the adsorption were established and the adsorption data for AA fitted Dubinin-Radushkevich (D-R) isotherm well, whereas FA followed Langmuir isotherm. The kinetic data were examined. It was found that pseudo-second-order kinetic model was found to adequately explain the sorption kinetic of AA and FA from aqueous solution. It was again found that intraparticle diffusion was found to explain the adsorption mechanism. Adsorption thermodynamic parameters were estimated and the negative values of ∆G showed that the adsorption process was feasible and spontaneous in nature, while the negative values of ∆H indicate that the adsorption process was exothermic. It is therefore established that SB-AC has good potential for the removal of AA and FA from aqueous solution. Hence, it should find application in the regular treatment of polluted water in aquaculture and fish breeding system.

  13. 3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid

    PubMed Central

    Assaud, Loïc; Monyoncho, Evans; Pitzschel, Kristina; Allagui, Anis; Petit, Matthieu; Hanbücken, Margrit

    2014-01-01

    Summary Three-dimensionally (3D) nanoarchitectured palladium/nickel (Pd/Ni) catalysts, which were prepared by atomic layer deposition (ALD) on high-aspect-ratio nanoporous alumina templates are investigated with regard to the electrooxidation of formic acid in an acidic medium (0.5 M H2SO4). Both deposition processes, Ni and Pd, with various mass content ratios have been continuously monitored by using a quartz crystal microbalance. The morphology of the Pd/Ni systems has been studied by electron microscopy and shows a homogeneous deposition of granularly structured Pd onto the Ni substrate. X-ray diffraction analysis performed on Ni and NiO substrates revealed an amorphous structure, while the Pd coating crystallized into a fcc lattice with a preferential orientation along the [220]-direction. Surface chemistry analysis by X-ray photoelectron spectroscopy showed both metallic and oxide contributions for the Ni and Pd deposits. Cyclic voltammetry of the Pd/Ni nanocatalysts revealed that the electrooxidation of HCOOH proceeds through the direct dehydrogenation mechanism with the formation of active intermediates. High catalytic activities are measured for low masses of Pd coatings that were generated by a low number of ALD cycles, probably because of the cluster size effect, electronic interactions between Pd and Ni, or diffusion effects. PMID:24605281

  14. Theoretical Modeling of Formic Acid (HCOOH), Formate (HCOO(-)), and Ammonia (NH(4)) Vibrational Spectra in Astrophysical Ices

    NASA Technical Reports Server (NTRS)

    Park, Jin-Young; Woon, David E.

    2006-01-01

    Ions embedded in icy grain mantles are thought to account for various observed infrared spectroscopic features, particularly in certain young stellar objects. The dissociation of formic acid (HCOOH) in astrophysical ices to form the formate ion (HCOO(-)) was modeled with density functional theory cluster calculations. Like isocyanic acid (HOCN), HCOOH was found to spontaneously deprotonate when sufficient water is present to stabilize charge transfer complexes. Both ammonia and water can serve as proton acceptors, yielding ammonium (NH4(+)) and hydronium (H3O(+)) counterions. Computed frequencies of weak infrared features produced by stretching and bending modes in both HCOO(-) and HCOOH were compared with experimental and astronomical data. Our results confirm laboratory assignments that a band at 1381 cm(exp -1) can be attributed to the CH bend in either HCOO(-) or HCOOH, but a band at 1349 cm(exp -1) corresponds to CO stretching in HCOO(-). Another feature at 1710 cm(exp -1) (5.85 m) can possibly be assigned to a CO stretching mode in HCOOH, as suggested by experiment, but the agreement is less satisfactory. In addition, we examine and analyze spectroscopic features associated with NH+4, both as a counterion to HCOO(-) or OCN(-) and in isolation, in order to compare with experimental and astronomical data in the 7 m region.

  15. Theoretical Modeling of Formic Acid (HCOOH), Formate (HCOO(-)), and Ammonia (NH(4)) Vibrational Spectra in Astrophysical Ices

    NASA Technical Reports Server (NTRS)

    Park, Jin-Young; Woon, David E.

    2006-01-01

    Ions embedded in icy grain mantles are thought to account for various observed infrared spectroscopic features, particularly in certain young stellar objects. The dissociation of formic acid (HCOOH) in astrophysical ices to form the formate ion (HCOO(-)) was modeled with density functional theory cluster calculations. Like isocyanic acid (HOCN), HCOOH was found to spontaneously deprotonate when sufficient water is present to stabilize charge transfer complexes. Both ammonia and water can serve as proton acceptors, yielding ammonium (NH4(+)) and hydronium (H3O(+)) counterions. Computed frequencies of weak infrared features produced by stretching and bending modes in both HCOO(-) and HCOOH were compared with experimental and astronomical data. Our results confirm laboratory assignments that a band at 1381 cm(exp -1) can be attributed to the CH bend in either HCOO(-) or HCOOH, but a band at 1349 cm(exp -1) corresponds to CO stretching in HCOO(-). Another feature at 1710 cm(exp -1) (5.85 m) can possibly be assigned to a CO stretching mode in HCOOH, as suggested by experiment, but the agreement is less satisfactory. In addition, we examine and analyze spectroscopic features associated with NH+4, both as a counterion to HCOO(-) or OCN(-) and in isolation, in order to compare with experimental and astronomical data in the 7 m region.

  16. Synthesis of hollow and nanoporous gold/platinum alloy nanoparticles and their electrocatalytic activity for formic acid oxidation.

    PubMed

    Lee, Doori; Jang, Ho Young; Hong, Soonchang; Park, Sungho

    2012-12-15

    In this work, hollow Au/Pt alloy nanoparticles (NPs) with porous surfaces were synthesized in a two-step procedure. In the first step, tri-component Ag/Au/Pt alloy NPs were synthesized through the galvanic replacement reaction between Ag NPs and aqueous solutions containing a mixture of HAuCl(4) and H(2)PtCl(4). In the second step, the Ag component was selectively dealloyed with nitric acid (HNO(3)), resulting in hollow di-component Au/Pt alloy NPs with a porous surface morphology. The atomic ratio of Au to Pt in the NPs was easily tunable by controlling the molar ratio of the precursor solution (HAuCl(4) and H(2)PtCl(6)). Hollow, porous Au/Pt alloy NPs showed enhanced catalytic activity toward formic acid electrooxidation compared to the analogous pure Pt NPs. This improved activity can be attributable to the suppression of CO poisoning via the "ensemble" effect. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Observations of formic and acetic acid by chemical ionization mass spectrometry in the Deep Convective Clouds and Chemistry Experiment

    NASA Astrophysics Data System (ADS)

    Treadaway, V.; McNeill, A.; Heikes, B.; O'Sullivan, D. W.; Silwal, I.

    2013-12-01

    Formic (HFo) and acetic acid (HAc) are part of the atmospheric processing of carbon and their measurement is relevant to defining oxygenated volatile organic carbon (OVOC) emissions, to examining photochemical processing of volatile organic carbon (VOC) and OVOCs, and to the photochemical processing of organic aerosol. Further, they can serve as photochemical tracers of convective transport, cloud chemical processes, and precipitation scavenging. The addition of HFo and HAc measurements to the Deep Convective Clouds and Chemistry Experiment (DC3) is relevant to the DC3 science objectives and complements the suite of chemicals already observed during DC3. The peroxide chemical ionization mass spectrometer (PCIMS) was flown aboard the NCAR Gulfstream-V platform in DC3 and while its primary function was to observe hydrogen peroxide and methylhydroperoxide it recorded signals attributed to iodide cluster ions of HFo and HAc at mass-charge ratios of 173 and 187, respectively. Post-mission laboratory experiments were performed to determine the CIMS instrument's sensitivity to these acids under the varying water vapor and sample flow conditions encountered during DC3 flights. The results of field measurements, laboratory experiments and the HFo and HAc recovery process are reported and HFo and HAc measurement quality assessed. The resultant HFo and HAc data are presented and interpreted with respect to atmospheric chemistry within measurement constraints. The DC3 observations were made in May and June 2012 and extended from the surface to 13 km over the central United States.

  18. Design and synthesis of palladium/graphitic carbon nitride/carbon black hybrids as high-performance catalysts for formic acid and methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Qian, Huayu; Huang, Huajie; Wang, Xin

    2015-02-01

    Here we report a facile two-step method to synthesize high-performance palladium/graphitic carbon nitride/carbon black (Pd/g-C3N4/carbon black) hybrids for electrooxidizing formic acid and methanol. The coating of g-C3N4 on carbon black surface is realized by a low-temperature heating treatment, followed by the uniform deposition of palladium nanoparticles (Pd NPs) via a wet chemistry route. Owning to the significant synergistic effects of the individual components, the preferred Pd/g-C3N4/carbon black electrocatalyst exhibits exceptional forward peak current densities as high as 2155 and 1720 mA mg-1Pd for formic acid oxidation in acid media and methanol oxidation in alkaline media, respectively, far outperforming the commercial Pd-C catalyst. The catalyst also shows reliable stability, demonstrating that the newly-designed hybrids have great promise in constructing high-performance portable fuel cell systems.

  19. Enhanced photocatalytic reduction of aqueous Pb(II) over Ag loaded TiO2 with formic acid as hole scavenger.

    PubMed

    Li, Liyuan; Jiang, Fang; Liu, Jingliang; Wan, Haiqin; Wan, Yuqiu; Zheng, Shourong

    2012-01-01

    In the present study, photocatalytic Pb(II) reduction over TiO(2) and Ag/TiO(2) catalysts in the presence of formic acid was explored to eliminate Pb(II) pollution in water. Ag/TiO(2) catalysts were prepared by the photo-deposition method and characterized using UV-Vis diffuse reflectance spectra, X-ray reflection diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Ag deposition on TiO(2) led to enhanced photocatalytic Pb(II) reduction and the Ag/TiO(2) catalyst with a Ag loading amount of 0.99 wt.% exhibited the optimum photocatalytic activity. For Pb(II) reduction over Ag/TiO(2) with a Ag loading amount of 0.99 wt.%, initial Pb(II) reduction rate was found to be dependent on the initial concentrations of formic acid and Pb(II). Increasing initial Pb(II) concentration led to linearly increased initial Pb(II) reduction rate. At low formic acid concentration, in parallel, initial Pb(II) reduction rates increased with formic concentration, but remained nearly identical at high formic acid concentration. Solution pH impacted the photocatalytic Pb(II) reduction and after irradiation for 100 min Pb(II) was removed by 11.8%, 91.2% and 98.6% at pH of 0.8, 2.0 and 3.5, respectively, indicative of enhanced Pb(II) reduction with pH in the tested pH range. The results showed that Ag/TiO(2) displayed superior catalytic activity to TiO(2), highlighting the potential of using Ag/TiO(2) as a more effective catalyst for photocatalytic Pb(II) reduction.

  20. Extraction of formic and acetic acids from aqueous solution by dynamic headspace-needle trap extraction temperature and pH optimization.

    PubMed

    Lou, Da-Wei; Lee, Xinqing; Pawliszyn, Janusz

    2008-08-08

    A combined method of dynamic headspace-needle trap sample preparation and gas chromatography for the determination of formic and acetic acids in aqueous solution was developed in this study. A needle extraction device coupled with a gas aspirating pump was intended to perform sampling and preconcentration of target compounds from aqueous sample before gas chromatographic analysis. The needle trap extraction (NTE) technique allows for the successful sampling of short chain fatty acids under dynamic conditions while keeping the headspace (HS) volume constant. Two important parameters, including extraction temperature and effect of acidification, have been optimized and evaluated using the needle trap device. The method detection limits for the compounds estimated were 87.2microg/L for acetic acid and 234.8microg/L for formic acid in spite of the low flame ionization detection response for formic acid and its low Henry's law constant in aqueous solution. Precision was determined based on the two real samples and ranged between 4.7 and 10.7%. The validated headspace-needle trap extraction method was also successfully applied to several environmental samples.

  1. The electroplated Pd-Co alloy film on 316 L stainless steel and the corrosion resistance in boiling acetic acid and formic acid mixture with stirring

    NASA Astrophysics Data System (ADS)

    Li, Sirui; Zuo, Yu; Tang, Yuming; Zhao, Xuhui

    2014-12-01

    Pd-Co alloy films were deposited on 316 L stainless steel by electroplating. Scanning electronic microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, weight loss test and polarization test were used to determine the properties of the Pd-Co alloy films. The Pd-Co films show fine grain size, low porosity and obviously high micro-hardness. The Co content in the film can be controlled in a large range from 21.9 at.% to 57.42 at.%. Pd is rich on the Pd-Co film surface, which is benefit to increase the corrosion resistance. In boiling 90% acetic acid plus 10% formic acid mixture with 0.005 M Br- under stirring, the Pd-Co plated stainless steel samples exhibit evidently better corrosion resistance in contrast to Pd plated samples. The good corrosion resistance of the Pd-Co alloy film is explained by the better compactness, the lower porosity, and the obviously higher micro-hardness of the alloy films, which increases the resistance to erosion and retards the development of micro-pores in the film.

  2. Different catalytic effects of a single water molecule: the gas-phase reaction of formic acid with hydroxyl radical in water vapor.

    PubMed

    Anglada, Josep M; Gonzalez, Javier

    2009-12-07

    The effect of a single water molecule on the reaction mechanism of the gas-phase reaction between formic acid and the hydroxyl radical was investigated with high-level quantum mechanical calculations using DFT-B3LYP, MP2 and CCSD(T) theoretical approaches in concert with the 6-311+G(2df,2p) and aug-cc-pVTZ basis sets. The reaction between HCOOH and HO has a very complex mechanism involving a proton-coupled electron transfer process (pcet), two hydrogen-atom transfer reactions (hat) and a double proton transfer process (dpt). The hydroxyl radical predominantly abstracts the acidic hydrogen of formic acid through a pcet mechanism. A single water molecule affects each one of these reaction mechanisms in different ways, depending on the way the water interacts. Very interesting is also the fact that our calculations predict that the participation of a single water molecule results in the abstraction of the formyl hydrogen of formic acid through a hydrogen atom transfer process (hat).

  3. Characterization of Au and Bimetallic PtAu Nanoparticles on PDDA-Graphene Sheets as Electrocatalysts for Formic Acid Oxidation.

    PubMed

    Yung, Tung-Yuan; Liu, Ting-Yu; Huang, Li-Ying; Wang, Kuan-Syun; Tzou, Huei-Ming; Chen, Po-Tuan; Chao, Chi-Yang; Liu, Ling-Kang

    2015-12-01

    Nanocomposite materials of the Au nanoparticles (Au/PDDA-G) and the bimetallic PtAu nanoparticles on poly-(diallyldimethylammonium chloride) (PDDA)-modified graphene sheets (PtAu/PDDA-G) were prepared with hydrothermal method at 90 °C for 24 h. The composite materials Au/PDDA-G and PtAu/PDDA-G were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) for exploring the structural characterization for the electrochemical catalysis. According to TEM results, the diameter of Au and bimetallic PtAu nanoparticles is about 20-50 and 5-10 nm, respectively. X-ray diffraction (XRD) results indicate that both of PtAu and Au nanoparticles exhibit the crystalline plane of (111), (200), (210), and (311). Furthermore, XRD data also show the 2°-3° difference between pristine graphene sheets and the PDDA-modified graphene sheets. For the catalytic activity tests of Au/PDDA-G and PtAu/PDDA-G, the mixture of 0.5 M aqueous H2SO4 and 0.5 M aqueous formic acid was used as model to evaluate the electrochemical characterizations. The catalytic activities of the novel bimetallic PtAu/graphene electrocatalyst would be anticipated to be superior to the previous electrocatalyst of the cubic Pt/graphene.

  4. Enzymatic Electrosynthesis of Formic Acid through CO2 Reduction in Bioelectrochemical System (BES): Effect of Immobilization and Carbonic Anhydrase Addition.

    PubMed

    Srikanth, Sandipam; Alvarez Gallego, Yolanda; Vanbroekhoven, Karolien; Pant, Deepak

    2017-03-17

    Enzymatic electrosynthesis of formic acid from carbon dioxide (CO2) reduction using formate dehydrogenase (FDH) as catalyst at cathode both in its free and immobilized forms was studied in detail in bioelectrochemical system (BES). The essential role of solubilizing CO2 for its conversion was also studied by adding carbonic anhydrase (CA) to the FDH enzyme both in free and immobilized forms. FDH alone in the free form showed large variation in reduction current (-6.2±3.9 A/m2), while the immobilized form showed less variation (-3.8±0.5 A/m2) due to increased enzyme stability. Addition of CA with FDH increased the current consumption in both forms due to the fact that it makes the CO2 rapidly dissolve and available for the catalytic reaction of FDH. Remarkably stable current consumption was observed throughout operation when both the CA and FDH were immobilized onto the electrode (-3.9±0.2 A/m2). The product formation by the immobilized enzyme was also continued for 3 repetitive cycles indicating the longevity of the enzyme after immobilization. NADH recyclability was also clearly evidenced on the derivative voltammetric signature. Extension of this study for continuous and long-term operation may reveal more possibilities for the rapid CO2 capture and conversion.

  5. Development of an Iridium‐Based Catalyst for High‐Pressure Evolution of Hydrogen from Formic Acid

    PubMed Central

    Iguchi, Masayuki; Himeda, Yuichiro; Manaka, Yuichi

    2016-01-01

    Abstract A highly efficient and recyclable Ir catalyst bearing a 4,7‐dihydroxy‐1,10‐phenanthroline ligand was developed for the evolution of high‐pressure H2 gas (>100 MPa), and a large amount of atmospheric pressure H2 gas (>120 L), over a long term (3.5 months). The reaction proceeds through the dehydrogenation of highly concentrated aqueous formic acid (FA, 40 vol %, 10 mol L−1) at 80 °C using 1 μmol of catalyst, and a turnover number (TON) of 5 000 000 was calculated. The Ir catalyst precipitated after the reaction owing to its pH‐dependent solubility in water, and 94 mol % was recovered by filtration. Thus, it can be treated and recycled like a heterogeneous catalyst. The catalyst was successfully recycled over 10 times for highpressure FA dehydrogenation at 22 MPa without any treatment or purification. PMID:27530918

  6. The effect of hydrogen peroxide concentration and solid loading on the fractionation of biomass in formic acid.

    PubMed

    Dussan, K; Girisuta, B; Haverty, D; Leahy, J J; Hayes, M H B

    2014-10-13

    This study investigated the fractionation of biomass using a decomposing mixture of hydrogen peroxide-formic acid as a pretreatment for the biorefining of Miscanthus × giganteus and of sugarcane bagasse. The main parameters investigated were the hydrogen peroxide concentration (2.5, 5.0 and 7.5 wt%) and biomass loading (5.0 and 10.0 wt%). At the highest hydrogen peroxide concentration used (7.5 wt%), the energy released by the decomposition of the H2O2 could heat the reaction mixture up to 180 °C in a short time (6-16 min). As a result, highly delignified pulps, with lignin removal as high as 92 wt%, were obtained. This delignification process also solubilised a significant amount of pentosan (82-98 wt%) from the initial biomass feedstock, and the resulting pulp had a high cellulosic content (92 wt%). The biomass loading only affected the reaction rate of hydrogen peroxide decomposition. Various analytical methods, including Fourier transform infrared spectroscopy, and thermogravimetric and elemental analyses, characterized the lignin obtained.

  7. Characterization of Au and Bimetallic PtAu Nanoparticles on PDDA-Graphene Sheets as Electrocatalysts for Formic Acid Oxidation

    NASA Astrophysics Data System (ADS)

    Yung, Tung-Yuan; Liu, Ting-Yu; Huang, Li-Ying; Wang, Kuan-Syun; Tzou, Huei-Ming; Chen, Po-Tuan; Chao, Chi-Yang; Liu, Ling-Kang

    2015-09-01

    Nanocomposite materials of the Au nanoparticles (Au/PDDA-G) and the bimetallic PtAu nanoparticles on poly-(diallyldimethylammonium chloride) (PDDA)-modified graphene sheets (PtAu/PDDA-G) were prepared with hydrothermal method at 90 °C for 24 h. The composite materials Au/PDDA-G and PtAu/PDDA-G were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) for exploring the structural characterization for the electrochemical catalysis. According to TEM results, the diameter of Au and bimetallic PtAu nanoparticles is about 20-50 and 5-10 nm, respectively. X-ray diffraction (XRD) results indicate that both of PtAu and Au nanoparticles exhibit the crystalline plane of (111), (200), (210), and (311). Furthermore, XRD data also show the 2°-3° difference between pristine graphene sheets and the PDDA-modified graphene sheets. For the catalytic activity tests of Au/PDDA-G and PtAu/PDDA-G, the mixture of 0.5 M aqueous H2SO4 and 0.5 M aqueous formic acid was used as model to evaluate the electrochemical characterizations. The catalytic activities of the novel bimetallic PtAu/graphene electrocatalyst would be anticipated to be superior to the previous electrocatalyst of the cubic Pt/graphene.

  8. Deciphering visible light photoreductive conversion of CO2 to formic acid and methanol using waste prepared material.

    PubMed

    Zhang, Qian; Lin, Cheng-Fang; Chen, Bor-Yann; Ouyang, Tong; Chang, Chang-Tang

    2015-02-17

    As gradual increases in atmospheric CO2 and depletion of fossil fuels have raised considerable public concern in recent decades, utilizing the unlimited solar energy to convert CO2 to fuels (e.g., formic acid and methanol) apparently could simultaneously resolve these issues for sustainable development. However, due to the complicated characteristics of CO2 reduction, the mechanism has yet to be disclosed. To clarify the postulated pathway as mentioned in the literature, the technique of electron paramagnetic resonance (ESR) was implemented herein to confirm the mechanism and related pathways of CO2 reduction under visible light using graphene-TiO2 as catalyst. The findings indicated that CO(-•) radicals, as the main intermediates, were first detected herein to react with several hydrogen ions and electrons for the formation of CH3OH. For example, the generation of CO(-•) radicals is possibly the vital rate-controlling step for conversion of CO2 to methanol as hypothesized elsewhere. The kinetics behind the proposed mechanism was also determined in this study. The mechanism and kinetics could provide the in-depth understanding to the pathway of CO2 reduction and disclose system optimization of maximal conversion for further application.

  9. Highly efficient and autocatalytic H2O dissociation for CO2 reduction into formic acid with zinc

    PubMed Central

    Jin, Fangming; Zeng, Xu; Liu, Jianke; Jin, Yujia; Wang, Lunying; Zhong, Heng; Yao, Guodong; Huo, Zhibao

    2014-01-01

    Artificial photosynthesis, specifically H2O dissociation for CO2 reduction with solar energy, is regarded as one of the most promising methods for sustainable energy and utilisation of environmental resources. However, a highly efficient conversion still remains extremely challenging. The hydrogenation of CO2 is regarded as the most commercially feasible method, but this method requires either exotic catalysts or high-purity hydrogen and hydrogen storage, which are regarded as an energy-intensive process. Here we report a highly efficient method of H2O dissociation for reducing CO2 into chemicals with Zn powder that produces formic acid with a high yield of approximately 80%, and this reaction is revealed for the first time as an autocatalytic process in which an active intermediate, ZnH− complex, serves as the active hydrogen. The proposed process can assist in developing a new concept for improving artificial photosynthetic efficiency by coupling geochemistry, specifically the metal-based reduction of H2O and CO2, with solar-driven thermochemistry for reducing metal oxide into metal. PMID:24675820

  10. Dehydrogenation of Formic Acid at Room Temperature: Boosting Palladium Nanoparticle Efficiency by Coupling with Pyridinic-Nitrogen-Doped Carbon.

    PubMed

    Bi, Qing-Yuan; Lin, Jian-Dong; Liu, Yong-Mei; He, He-Yong; Huang, Fu-Qiang; Cao, Yong

    2016-09-19

    The use of formic acid (FA) to produce molecular H2 is a promising means of efficient energy storage in a fuel-cell-based hydrogen economy. To date, there has been a lack of heterogeneous catalyst systems that are sufficiently active, selective, and stable for clean H2 production by FA decomposition at room temperature. For the first time, we report that flexible pyridinic-N-doped carbon hybrids as support materials can significantly boost the efficiency of palladium nanoparticle for H2 generation; this is due to prominent surface electronic modulation. Under mild conditions, the optimized engineered Pd/CN0.25 catalyst exhibited high performance in both FA dehydrogenation (achieving almost full conversion, and a turnover frequency of 5530 h(-1) at 25 °C) and the reversible process of CO2 hydrogenation into FA. This system can lead to a full carbon-neutral energy cycle. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Fabrication of Nitrogen-Doped Mesoporous-Carbon-Coated Palladium Nanoparticles: An Intriguing Electrocatalyst for Methanol and Formic Acid Oxidation.

    PubMed

    Ray, Chaiti; Dutta, Soumen; Sahoo, Ramkrishna; Roy, Anindita; Negishi, Yuichi; Pal, Tarasankar

    2016-05-20

    Inspired by the attractive catalytic properties of palladium and the inert nature of carbon supports in catalysis, a concise and simple methodology for in situ nitrogen-doped mesoporous-carbon-supported palladium nanoparticles (Pd/N-C) has been developed by carbonizing a palladium dimethylglyoximate complex. The as-synthesized Pd/N-C has been exfoliated as a fuel cell catalyst by studying the electro-oxidation of methanol and formic acid. The material synthesized at 400 °C,namely, Pd/N-C-400,exhibitssuperior mass activity and stability among catalysts synthesized under different carbonization temperaturesbetween300 and 500 °C. The unique 1D porous structure in Pd/N-C-400 helps better electron transport at the electrode surface, which eventually leads to about five times better catalytic activity and about two times higher stability than that of commercial Pd/C. Thus, our designed sacrificial metal-organic templatedirected pathway becomes a promising technique for Pd/N-C synthesis with superior catalytic performances. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Preparation of Pd-Co-based nanocatalysts and their superior applications in formic acid decomposition and methanol oxidation.

    PubMed

    Qin, Yu-ling; Liu, Ya-cheng; Liang, Fei; Wang, Li-min

    2015-01-01

    Formic acid (FA) and methanol, as convenient hydrogen-containing materials, are most widely used for fuel cells. However, using suitable and low-cost catalysts to further improve their energy performance still is a matter of great significance. Herein, PdCo and PdCo@Pd nanocatalysts (NCs) are successfully prepared by the facile method. Pd 3d binding energy decreases due to the presence of Co. Consequently, PdCo@Pd NCs exhibit high catalytic activity and selectivity toward FA dehydrogenation at room temperature. The gas-generation rate at 30 min is 65.4 L h(-1)  g(-1) . PdCo/C has the worst catalytic performance in this reaction, despite the fact that it has a high gas-generation rate in the initial 30 min. Furthermore, both PdCo and PdCo@Pd NCs have enhanced electrocatalytic performance toward methanol oxidation. Their maximum currents are 966 and 1205 mA mg(-1) , respectively, which is much higher than monometallic Pd/C. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Long-lasting oscillations in the electro-oxidation of formic acid on PtSn intermetallic surfaces.

    PubMed

    Perini, Nickson; Batista, Bruno C; Angelo, Antonio C D; Epstein, Irving R; Varela, Hamilton

    2014-06-23

    Even when in contact with virtually infinite reservoirs, natural and manmade oscillators typically drift in phase space on a time-scale considerably slower than that of the intrinsic oscillator. A ubiquitous example is the inexorable aging process experienced by all living systems. Typical electrocatalytic reactions under oscillatory conditions oscillate for only a few dozen stable cycles due to slow surface poisoning that ultimately results in destruction of the limit cycle. We report the observation of unprecedented long-lasting temporal oscillations in the electro-oxidation of formic acid on an ordered intermetallic PtSn phase. The introduction of Sn substantially increases the catalytic activity and retards the irreversible surface oxidation, which results in the stabilization of more than 2200 oscillatory cycles in about 40 h; a 30-40-fold stabilization with respect to the behavior of pure Pt surfaces. The dynamics were modeled and numerical simulations point to the surface processes underlying the high stability. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation.

    PubMed

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  15. Acrylonitrile-contamination induced enhancement of formic acid electro-oxidation at platinum nanoparticles modified glassy carbon electrodes

    NASA Astrophysics Data System (ADS)

    El-Nagar, Gumaa A.; Mohammad, Ahmad M.; El-Deab, Mohamed S.; Ohsaka, Takeo; El-Anadouli, Bahgat E.

    2014-11-01

    Minute amount (∼1 ppm) of acrylonitrile (AcN), a possible contaminant, shows an unexpected enhancement for the direct electro-oxidation of formic acid (FAO) at Pt nanoparticles modified GC (nano-Pt/GC) electrodes. This is reflected by a remarkable increase of the current intensity of the direct oxidation peak (Ipd, at ca. 0.3 V) in the presence of AcN, concurrently with a significant decrease of the second (indirect) oxidation current (Ipind, at ca. 0.7 V), compared to that observed in the absence of AcN (i.e., at the unpoisoned Pt electrode). The extent of enhancement depends on the surface coverage (θ) of AcN at the surface of Pt nanoparticles. AcN is thought to favor the direct FAO by disturbing the contiguity of the Pt sites, which is necessary for CO adsorption. Furthermore, XPS measurements revealed a change in the electronic structure of Pt in presence of AcN, which has a favorable positive impact on the charge transfer during the direct FAO.

  16. Facile synthesis of palladium right bipyramids and their use as seeds for overgrowth and as catalysts for formic acid oxidation.

    PubMed

    Xia, Xiaohu; Choi, Sang-Il; Herron, Jeffrey A; Lu, Ning; Scaranto, Jessica; Peng, Hsin-Chieh; Wang, Jinguo; Mavrikakis, Manos; Kim, Moon J; Xia, Younan

    2013-10-23

    Controlling the shape and thus facets of metal nanocrystals is an effective way to enhance their performance in catalytic reactions. While Pd nanocrystals with a myriad of shapes have been successfully prepared with good uniformity and in high yield, Pd right bipyramids (RBPs) that have a singly twinned structure have been elusive. We report a facile route based on polyol reduction for the synthesis of Pd RBPs with purity >90% and sizes controlled in the range 5-15 nm. The success of our synthesis relies on the use of iodide ions to manipulate the strength of an oxidative etchant and selectively cap the Pd{100} facets. The as-prepared RBPs could serve as seeds to generate a set of Pd nanocrystals with novel shapes and structures. The RBPs also exhibited enhanced catalytic activity toward formic acid oxidation, with a current density 2.5 and 7.1 times higher than those of the single-crystal Pd nanocubes (which were also mainly covered by {100} facets) and commercial Pd black, respectively.

  17. One-step electrochemical synthesis of preferentially oriented (111) Pd nanocrystals supported on graphene nanoplatelets for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Chen, Qing-Song; Xu, Zhong-Ning; Peng, Si-Yan; Chen, Yu-Min; Lv, Dong-Mei; Wang, Zhi-Qiao; Sun, Jing; Guo, Guo-Cong

    2015-05-01

    Pd nanocrystals supported on graphene nanoplatelets (Pd/GNP) have been successfully synthesized by simultaneously electrochemical milling of Pd wire and graphite rod. It should be stressed that without the assistance of graphite rod, the Pd nanocrystals are unable to be obtained individually from Pd wire under the same conditions. Investigations of SEM and TEM demonstrate that Pd/GNP are preferentially decorated with (111) faceted nanocrystals. XPS studies confirm the strong metal-support interaction in Pd/GNP and reveal the surface is almost composed of Pd(0) species. Electrochemical measurements show that the prepared Pd based catalyst exhibits superior electrocatalytic activity towards formic acid oxidation, which may be attributed to the combined effects involving the preferentially oriented (111) surface structure, specific electronic structure and high dispersion of Pd nanocrystals as well as the support effects of graphene nanoplatelets. The synthesis method is simple and effective to prepare excellent new carbon-supported electrocatalysts, which is of great significance for direct organic molecule fuel cell.

  18. Nitrogen-doped carbon-TiO2 composite as support of Pd electrocatalyst for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Qin, Yuan-Hang; Li, Yunfeng; Lam, Thomas; Xing, Yangchuan

    2015-06-01

    We report Pd nanoparticles supported on a composite consisting of oxide TiO2 and nitrogen-doped carbon for formic acid oxidation (FAO). The nitrogen-doped carbon-TiO2 (NCx-TiO2) composite support was prepared by a simple polymerization-pyrolysis process using commercial TiO2 nanoparticles (P25). Surface analysis showed that elements of Ti, C, O, and N were present on the composite surface, on which nitrogen existed in both pyridinic and quaternary forms. Pd nanoparticles with a mean size of ca. 4 nm were uniformly deposited on the composite via a polyol process. Electrochemical characterizations showed that the NCx-TiO2-supported Pd particles (Pd/NCx-TiO2) exhibited an electrocatalytic activity towards FAO that almost doubled that of the carbon black-supported Pd particles (Pd/C) with much enhanced electrocatalytic stability. The better performance of the composite supported Pd was attributed to a possible electronic structure modification in the metallic Pd particles and bifunctional effect produced by the NCx-TiO2 composite.

  19. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  20. An ambient aqueous synthesis for highly dispersed and active Pd/C catalyst for formic acid electro-oxidation

    NASA Astrophysics Data System (ADS)

    Cheng, Niancai; Lv, Haifeng; Wang, Wei; Mu, Shichun; Pan, Mu; Marken, Frank

    An experimentally simple process is reported in aqueous solution and under ambient conditions to prepare highly dispersed and active Pd/C catalyst without the use of a stabilizing agent. The [Pd(NH 3) 4] 2+ ion is synthesized with gentle heating in aqueous ammonia solution without formation of Pd(OH) x complex intermediates. The adsorbed [Pd(NH 3) 4] 2+ on the surface of carbon (Vulcan XC-72) is reduced in situ to Pd nanoparticles by NaBH 4. The Pd/C catalyst obtained is characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that highly dispersed Pd/C catalyst with 20 wt.% Pd content and with an average Pd nanoparticle diameter of 4.3-4.7 nm could be obtained. The electrochemical measurements show that the Pd/C catalyst without stabilizer has a higher electro-oxidation activity for formic acid compared to that of a Pd/C catalyst prepared in a traditional high temperature polyol process in ethylene glycol.