Photoreduction of carbon dioxide

A system comprised of Ru(bpj)3 as photosensitizer, triethanolamine as electron donor, and a charge relay such as the V,N -dimethyl-2,2 -bipyridinium ion, has been used for the photoreduction of carbon dioxide to methane and higher hydrocarbons. If the irradiation of this system is carried out in the presence of colloidal 

Ru or Os, the resulting products are methane, ethylene, and hydrogen. These reduction reactions of carbon dioxide proceed via an electron transfer pathway involving hydrogen ions and metal-activated carbon dioxide rather than by a hydrogenation route from the hydrogen that may be also formed in the photoreduction (Refs. 128 and 129)  

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Homogeneous, nanosized, copper-loaded anatase titania was synthesized by an improved sol-gel method [197], These titania composite photocatalysts were applied to the photoreduction of carbon dioxide to evaluate their photocatalytic performance. Methanol was found to be the primary hydrocarbon product [198], Under calcination conditions, small copper particles are well dispersed on the surface of anatase titania. According to XAS and XPS analysis, the oxidation state of Cu(I) was suggested to be the active species for C02 photoreduction [199], Higher copper dispersion and smaller copper particles on the titania surface are responsible for a great improvement in the performance of C02 photoreduction. 

Much of the work on the photoreduction of carbon dioxide centres on the use of transition metal catalysts to produce formic acid and carbon monoxide. A large number of these catalysts are metalloporphyrins and phthalocyanines. These include cobalt porphyrins and iron porphyrins, in which the metal in the porphyrin is first of all photochemically reduced from M(ii) to M(o), the latter reacting rapidly with CO to produce formic acid and CO. ° Because the M(o) is oxidised in the process to M(ii) the process is catalytic with high percentage conversion rates. However, there is a problem with light energy conversion and the major issue of porphyrin stability. 

Aurian-Blajeni B, Halmann M, Manasses J. Photoreduction of carbon dioxide and water into formaldehyde and methanol on semiconductor materials. Sol Energy 1980 25 165-70. 

It was found, that also Ru and Os colloids can act as catalysts for the photoreduction of carbon dioxide to methane [94, 95]. [Ru(bpy)3]2+ plays a role of a photosensitizer, triethanolamine (TEOA) works as an electron donor, while bipyridinium electron relays (R2+) mediate the electron transfer process. The production of hydrogen, methane, and small amounts of ethylene may be observed in such a system (Figure 21.1). Excited [Ru(bpy)3]2+ is oxidized by bipyridinium salts, whereas formed [Ru(bpy)3]3+ is reduced back to [Ru(bpy)3]2+ by TEOA. The reduced bipyridinium salt R + reduces hydrogen and C02 in the presence of metal colloids. Recombination of surface-bound H atoms competes with a multi-electron C02 reduction. More selective reduction of C02 to CH4, ethylene, and ethane was obtained using ruthenium(II)-trisbipyrazine, [Ru(bpz)3]2+/TEOA/Ru colloid system. The elimination of hydrogen evolution is thought to be caused by a kinetic barrier towards H2 evolution in the presence of [Ru(bpz)3]2+ and noble metal catalysts [96]. 

Inoue H,TorimotoT, Sakata T, Mori H,Yoneyama H. Photoreduction of carbon dioxide on quantized zinc sulfide. Chem Lett 1990 1483-6. 

C-F bonds are normally difficult to reduce, but it has now been shown that such bonds a to the carbonyl group of alkyl perfluoroesters can be photoreduced in hexamethylphosphorotriamide in a reaction which involves electron transfer from excited phosphoramide (Portella and Iznaden). Several reports of the photoreduction of carbon dioxide have appeared for photoreduction to methane see Yamase and Sugeta, and Diirr et al. for reduction to formate see Lehn and Ziessel, and Matsuoka et al. Gollnick and Held have reported that mercurochrome is an efficient sensitizer for type II singlet oxygen photo-oxygenations. 

Jeyalakshmi, V. Mahalakshmy, R. Krishnamurthy, K. R. Viswanathan, B. Titania Based Catalysts for Photoreduction of Carbon Dioxide Role of Modifiers. Indian J. Chem., 2012,51, 1263-1283. 

Kohno, Y. Tanaka, T. Funabiki, T. Yoshida, S. Photoreduction of carbon dioxide with hydrogen over Zr02. Chem Commun., 1997, 81, 841-842. 

Topics which have formed the subjects of reviews this year include excited state chemistry within zeolites, photoredox reactions in organic synthesis, selectivity control in one-electron reduction, the photochemistry of fullerenes, photochemical P-450 oxygenation of cyclohexene with water sensitized by dihydroxy-coordinated (tetraphenylporphyrinato)antimony(V) hexafluorophosphate, bio-mimetic radical polycyclisations of isoprenoid polyalkenes initiated by photo-induced electron transfer, photoinduced electron transfer involving C o/CjoJ comparisons between the photoinduced electron transfer reactions of 50 and aromatic carbonyl compounds, recent advances in the chemistry of pyrrolidino-fullerenes, ° photoinduced electron transfer in donor-linked fullerenes," supra-molecular model systems,and within dendrimer architecture,photoinduced electron transfer reactions of homoquinones, amines, and azo compounds, photoinduced reactions of five-membered monoheterocyclic compounds of the indigo group, photochemical and polymerisation reactions in solid Qo, photo- and redox-active [2]rotaxanes and [2]catenanes, ° reactions of sulfides and sulfenic acid derivatives with 02( Ag), photoprocesses of sulfoxides and related compounds, semiconductor photocatalysts,chemical fixation and photoreduction of carbon dioxide by metal phthalocyanines, and multiporphyrins as photosynthetic models. 

Kasuga, K. (1996) Chemical fixation and photoreduction of carbon dioxide catalyzed by metal phthalocyanine derivatives, in Phthalocyanines,... 

Borowska Z, Mauzerall D Photoreduction of carbon dioxide by aqueous ferrous ion An alternative to the strongly reducing atmosphere for the chemical origin of life. Proc Natl Acad Sci USA 1988, 85(18) 6577—6580. 

Eggins BR, Robertson PKJ, Stewart JH, Woods E Photoreduction of carbon dioxide on zinc sulfide to give four-carbon and two-carbon acids. J Ghem Soc Ghem Commun 1993, (4) 349—350. 

Inoue H, Moriwaki H, Maeda K, Yoneyama H Photoreduction of carbon-dioxide using chalcogenide semiconductor microcrystals. J Photochem Photobiol A Ghem 1995, 86(1-3) 191-196. 

Yoneyama H Photoreduction of carbon dioxide on quantized semiconductor nanoparticles in solution. Catalysis Today 1997, 39(3) 169-175. 

Kisch H, Twardzik G Heterogeneous photocatalysis 9. Zinc-sulfide catalyzed photoreduction of carbon dioxide. Chemische Berichte 1991, 124(5) ll6l— 1162. 

Kanemoto M, Shiragami T, Pac CJ, Yanagida S Semiconductor photocatalysis — effective photoreduction of carbon-dioxide catalyzed by ZnS quantum crystallites with low-density of surface-defects. J Phys Chem 1992, 96(8) 3521— 3526. 

Kimura, E., S. Wada, M. Shionoya, and Y. Okazaki (1994). New series of multifunctionalized nickel(II)-cyclam (cyclam = 1,4,8,11 tetraazacyclotetradecane) complexes. Application to the photoreduction of carbon dioxide. Inorg. Chem. 33, 770-778. 

Matsuoka, S., K. Kiichi, T. Ogata, M. Kasuba, N. Nakashima, E. Fujita, and S. Yanagida (1993). Efficient and selective electron mediation of cobalt complexes with cyclam and related macrocycles in the p-terphenyl-catalyzed photoreduction of carbon dioxide. J. Am. Chem Soc 115(2), 601-609. 

Premkumar, J. R., Ramaraj, R. (1997). Photoreduction of carbon dioxide by metal phthalocyanine adsorbed Nafion membrane. Chemical Communications, 343—344. http // dx.doi.org/10.1039/A607069H. 

In comparison to water photolysis [1,2] very little research has been directed at the photoreduction of carbon dioxide and at the photooxidation of carbon monoxide. There are several reasons why chemists should be interested in these two processes. CO2 is a natural and abundant raw material it is a major atmospheric pollutant, involved in the greenhouse effect which may ultimately affect the climate and the temperature of our planet [3]. CO is used in many important industrial processes e.g. carbonylation, hydroformylation, Fisher-Tropsch reactions, and it is one of the major contaminants of industrial gases produced during catalytic processes (e.g., Haber-Bosch synthesis of NH3[4]). There are also fundamental reasons for studying CO2 and CO activation. The former is an inert molecule with carbon in its highest oxidation state and therefore its activation is difficult to achieve. Carbon dioxide could either be reduced to... 

Uhnan M, Tinnemans AHA, Mackor A, Aurian-Blajeni B, Hahnann M (1982) Photoreduction of carbon dioxide to formic acid, formaldehyde, methanol, acetaldehyde and ethanol using aqueous suspensions of strontium titanate with transition metal additives. Int J Sol Energy 1 (3) 213-222... 

Guan G, Kida T, Harada T, Isayama M, Yoshida A (2003) Photoreduction of carbon dioxide with water over K2Ti60i3 photocatalyst combined with Cu)ZnO catalyst under concentrated sunlight. Appl Catal Gen 249 11-18... 

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