Carbon dioxide, hydrogenation formic acid

P. G. Jessop, Y. Hsiao, T. Ikariya, R. Noyori, Homogeneous Catalysis in Supercritical Fluids Hydrogenation of Supercritical Carbon Dioxide to Formic Acid, Alkyl Formates, and Formamides ,J. Am Chem Soc 1996,118, 344-355. 

It is therefore theoretically impossible to effect the complete decomposition of the formic acid present. In the electrolysis of sodium formate, carbon dioxide and formic acid are in fact always formed at the positive pole and hydrogen and sodium hydroxide at the negative pole. 

Formic AcicL—Wilde 7 found that the action of the electric spark on gaseous mixtures of oxygen and alcohol, hydrogen and carbon dioxide, and methane and carbon dioxide, produced formic acid. In the first and last mentioned of these mixtures acetic acid is also formed. 

A nice example of a homogeneous catalytic hydrogenation is the reduction of carbon dioxide to formic acid, carried out in SC-CO2 in the presence of a soluble ruthenium(II)-trimethylphosphane catalyst and triethylamine at 50 °C and 21 MPa... 

Jessop, P.G. Hsiao, Y. Ikariya, T. Noyori, R. Homogeneous catalysis in supercritical fluids hydrogenation of supercritical carbon dioxide to formic acid, alkyl formates, and formamides. J. Am. Chem. Soc. 1996, 118 (2), 344-55. 

Reduction of carbon dioxide to formic acid (and its derivatives) is a very active field of research that has been amply reviewed.18-20,37,3 8 While some of the results are close to commercialization, others can be regarded as promising developments. It should also be realized that presently H2 is generated on a fossil fuel basis (natural gas, coal) accompanied by the formation of C02. Therefore, the hydrogenation of carbon dioxide will not ease the C02 burden however, it can be very useful for synthetic purposes. 

Jessop and co-workers have pointed out that homogeneous catalysis in supercritical fluids can offer high rates, improved selectivity, and elimination of mass-transfer problems.169 They have used a ruthenium phosphine catalyst to reduce supercritical carbon dioxide to formic acid using hydrogen.170 The reaction might be used to recycle waste carbon dioxide from combustion. It also avoids the use of poisonous carbon monoxide to make formic acid and its derivatives. There is no need for the usual solvent for such a reaction, because the excess carbon dioxide is the solvent. If the reaction is run in the presence of dimethy-lamine, dimethylformamide is obtained with 100% selectivity at 92-94% conversion.171 In this example, the ruthenium phosphine catalyst was supported on silica. Asymmetric catalytic hydrogenation of dehydroaminoacid derivatives (8.16) can be performed in carbon dioxide using ruthenium chiral phosphine catalysts.172... 

Fig. (13). Photochemical reduction of carbon dioxide into formic acid using tricyclic tertiary amine as a sacrificial donor (a) Plant photosynthesis (b) amine radical cation formed from tricyclic amine (c) regeneration of amine by hydrogenation using Pd catalyst. Reproduced with permission from Ref. [58, 59]. 2011 McMillan Publishers Ltd.

In an attempt to elucidate the mechanism of these peroxide-carbohydrate reactions, a carefril study of products, particularly of gaseous ones, from various model compoimds has been undertaken. - Thus, formaldehyde gives hydrogen, carbon dioxide, and formic acid by the steps shown in equations (5) to (8). Using deuterated hydrogen peroxide, Bonhoeffer... 

Kuen has shown that gases from Fenton reagent-carbohydrate systems consist almost entirely of carbon dioxide. This fact has been exploited for simple, manometric studies of the iron (III) chloride-D-glucono-1,5-lactone-hydrogen peroxide reaction. Equivalent dismutation between carbohydrate fragments, or reduction of carbon dioxide to formic acid, have been suggested in order to account for the deficit (about 66%) in carbon dioxide arising from the oxidative scission. ... 

Hydrogenation of carbon dioxide to formic acid and decomposition of formic acid to dihydrogen and carbon dioxide... 

HYDROGENATION OF CARBON DIOXIDE TO FORMIC ACID AND DECOMPOSITION OF FORMIC ACID TO DIHYDROGEN AND CARBON DIOXIDE... 

Also, I wish to mention the catalytic reaction which proceeds via metathesis with heterolytic o-bond activation. Hydrogenation of carbon dioxide to formic acid is one of attractive transition-metal catalyzed CO2 fixation reactions. Rh(I), Rh(III), and Ru(II) complexes were used as a catalyst [54-56]. Of those catalysts, the Ru(II)-catalyzed hydrogenation of CO2 has drawn considerable interest because of its very high efficiency. Its catalytic cycle was theoretically investigated [57]. In this catalytic reaction, the first step is the insertion of CO2 into the Ru-H bond, to afford the ruthenium(II) formate complex, RuHIir -OCOHKPHjIj,... 

There are several reports on the use of MPc complexes as electrocatalysts for the reduction of CO2, but reports on the use of these complexes for the oxidation of CO are scarce. Diffusion electrodes have been employed extensively for the use of MPc complexes as electrocatalysts for CO2 reduction. Using porous gas diffusion electrodes, Fumya and coworkers studied the activity of a series of MPc complexes towards the reduction of CO2 and found the activity to be depended on the nature of the central metal. Table 7.4 . On FePc and PdPc modified electrodes both hydrogen and CO were obtained, on ZnPc and AlPc, the main products were hydrogen, carbon dioxide and formic acid and on H2PC, MgPc, MnPc,... 

Recently, acrylic acid methylester palladium complexes are able to react with carbon dioxide. The substituted compound with carbon dioxide affords formic acid by reaction with hydrogen at room temperatures. Therefore, the reaction is the fixation of carbon dioxide by palladium compounds. 

Ohnishi YY, Nakao Y, Sato H, Sakaki S (2006) Ruthenium(II)-catalyzed hydrogenation of carbon dioxide to formic acid. Theoretical study of significant acceleration by water molecules. Organometallics 25 3352-3363... 

Gassner, F. Leitner, W. (1993) C02-activation. 3. Hydrogenation of carbon-dioxide to formic acid using water-soluble rhodium catalysts, Chem. Commun., 1465-6. 

While efficient avenues for releasing hydrogen from formic acid have been demonstrated, the efficient synthesis of formic acid continues to be a challenge [55]. This state of affairs is smprising, if one considers that the electroreduction of carbon dioxide to formic acid has been studied for more than 140 years, and the first report on the process was published by Royer as early as in 1870 [127]. By the begirming of World War 1, an additional three papers had been released [128-130]. Nevertheless, the process still needs to be optimised for energy efficiency and selectivity [131,132]. 

As shown in Figure 1, the next step in the catalytic cycle of carbon dioxide hydrogenation is either reductive elimination of formic acid from the transition-metal formate hydride complex or CT-bond metathesis between the transition-metal formate complex and dihydrogen molecule. In this section, we will discuss the reductive elimination process. Activation barriers and reaction energies for different reactions of this type are collected in Table 3. 

The amount of liberated carbon dioxide was equimolar to the HCl adsorption. Rivin confirmed also that hydrogen peroxide is formed by reaction of carbon black with formic acid in the presence of oxygen. Physically adsorbed hydrochloric acid was removed by washing with dioxane. The remaining chloride ions on the surface were replaced by hydroxide ions on treatment with sodium hydroxide. The reaction was formulated as production of a carbinol ... 

Photolytic. Irradiation of vinyl chloride in the presence of nitrogen dioxide for 160 min produced formic acid, HCl, carbon monoxide, formaldehyde, ozone, and trace amounts of formyl chloride and nitric acid. In the presence of ozone, however, vinyl chloride photooxidized to carbon monoxide, formaldehyde, formic acid, and small amounts of HCl (Gay et al, 1976). Reported photooxidation products in the troposphere include hydrogen chloride and/or formyl chloride (U.S. EPA, 1985). In the presence of moisture, formyl chloride will decompose to carbon monoxide and HCl (Morrison and Boyd, 1971). Vinyl chloride reacts rapidly with OH radicals in the atmosphere. Based on a reaction rate of 6.6 x lO" cmVmolecule-sec, the estimated half-life for this reaction at 299 K is 1.5 d (Perry et al., 1977). Vinyl chloride reacts also with ozone and NO3 in the gas-phase. Sanhueza et al. (1976) reported a rate constant of 6.5 x 10 cmVmolecule-sec for the reaction with OH radicals in air at 295 K. Atkinson et al. (1988) reported a rate constant of 4.45 X 10cmVmolecule-sec for the reaction with NO3 radicals in air at 298 K. 

On the other hand, in two other papers, the formation of hydrogen gas was not mentioned, whereas carbon monoxide and formic acid were both observed as products. In studies carried out by Ogura and coworkers [123], electrogenerated [Co(PPh3)2L] (where L is a substituted quinoline, bipyridine, or phenan-throline moiety) was employed as a catalyst for the reduction of CO2 in anhydrous organic solvents, conditions for which the current efficiency for production of CO (the main product) was 83%. Similarly, in an investigation done by Behar et al. [124], who used cobalt porphyrins as catalysts in an acetonitrile medium, the formation of both carbon monoxide and formic acid was noted however, the catalytic species did not appear to contain cobalt(I), but rather a cobalt(O) species complexed with carbon dioxide. 

Coating the vessel with potassium chloride eliminated the chain reactions and simplified the kinetics. It was found that the quantum yields of hydrogen, carbon monoxide, and formic acid decreased with an increase in oxygen pressure in both coated and clean vessels. The quantum yield of carbon dioxide was large, ca. 3.0, variable (and, therefore, presumably heterogeneous) in the coated vessel, but in the clean vessel it increased with the oxygen pressure (Fig. 7). 

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