Catalytic hydrogenation of carbon dioxid

The rate of the catalytic hydrogenation of carbon dioxide to produce methane is... 

An interesting application of TSIL was developed by Zhang et al for the catalytic hydrogenation of carbon dioxide to make formic acid. Ruthenium immobilized on silica was dispersed in aqueous IL solution for the reaction. H2 and CO2 were reacted to produce formic acid in high yield and selectivity. The catalyst could easily be separated from the reaction mixture by filtration and the reaction products and the IL were separated by simple distillation. The TSIL developed for this reaction system was basic with a tertiary amino group (N(CH3)2) on the cation l-(A,A-dimethylaminoethyl)-2,3-dimethylimidazolium trifluoromethanesulfonate, [mammim] [TfO]. 

Catalytic hydrogenation of carbon dioxide is one of the crucial issues and processes to present a serious option for the global warming control. In particular, methanol synthesis has been considered to play an important role in the transportation of hydrogen energy derived from natural energy such as solar energy, hydropower and so on. 

The catalytic hydrogenation of carbon dioxide was performed in a continuous fixed bed reactor. The catalyst was reduced in a flow of hydrogen at 723 K for 20 - 24 hr. After the reduction, the catalyst was brought to the following conditions 573 K, 10 atm, space velocity of 1900 h-i and H2/CO2 = 3. The activity data was taken after 24h of reaction. The products were analyzed by a gas chromatograph (Chrompack CP 9001) equipped with thermal conductivity and flame ionization detectors. Carbon monoxide, carbon dioxide and water were analyzed on a Porapak Q column and the hydrocarbons on a GS Q capillary column. 

The effect of rhodium precursor on ethanol synthesis by catalytic hydrogenation of carbon dioxide over silica supported rhodium catalysts... 

Catalytic hydrogenation of carbon dioxide was studied for the simultaneous synthesis of methanol and dimethyl ether (oxygenates). Various combinations of methanol synthesis catalysts and methanol dehydration catalysts have been examined for the hydrogenation. The hybrid catalyst of Cu/ZnO/CraOs and CuNaY zeolite was found to be very efficient for the production of oxygenates. 

We present results on the catalytic hydrogenation of carbon dioxide to methanol in a conventional tubular packed-bed reactor filled with a copper based catalyst. In addition, results of an alternative approach using a dielectric-barrier discharge (DBD) reactor with and without the aid of a catalyst are presented. 

Methanol synthesis by catalytic hydrogenation of carbon dioxide is evaluated as one of the most promissing processes for conversion of carbon dioxide into valuable chemicals[l]. While various catalysts for methanol synthesis from carbon dioxide and hydrogen have been investigated, their durability - an important factor for evaluating their practicability-have not been reported[2,3,4,5]. The authors prepared CuO-ZnO-AI 2 O 3 catalysts for methanol synthesis from carbon dioxide and examined their activities and durabilities. 

Recent work by several research groups has shown that supercritical fluids can be superior to other solvents for several chemical processes. For example, DeSimone has demonstrated the ability of supercritical CO2 to replace Freons in the free radical polymerization of fluorinatkl acrylate monomers. 34) Noyori has shown that significant rate enhancements can be achieved in supercritical carbon dioxide relative to other solvents for the homogeneous catalytic hydrogenation of carbon dioxide to either formic acid or its derivatives in the presence of triethylamine or triethylamine/methanol respectively, (equation 1). (55-57) As discussed below, we have recently demonstrated that improved enantioselectivities can be achieved in supercritical carbon dioxide for the catalytic asymmetric hydrogenation of several enamides. 5 8)... 

Wang W, Wang S, Ma X, Gong J (2011) Recent advances in catalytic hydrogenation of carbon dioxide. Chem Soc Rev 40 3703-3727... 

Catalytic Hydrogenation of Carbon Dioxide to Formate Salts... 

Tanaka, R. Yamashita, M. Nozaki, K. Catalytic Hydrogenation of Carbon Dioxide Using Ir(III)-Pincer Complexes. J./l/M. Chem. Soc. 2009,131,14168-14169. 

Besides chemical catalytic reduction of carbon dioxide with hydrogen, which is already possible in the laboratory, we are exploring a new approach to recycling carbon dioxide into methyl alcohol or related oxygenates via aqueous eleetrocatalytic reduction using what can be called a regenerative fuel cell system. The direct methanol fuel cell... 

Other potential processes for production of formic acid that have been patented but not yet commerciali2ed include Hquid-phase oxidation (31) of methanol to methyl formate, and hydrogenation of carbon dioxide (32). The catalytic dehydrogenation of methanol to methyl formate (33) has not yet been adapted for formic acid production. 

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. 

Often intertwined with the catalytic reduction of carbon dioxide is the reduction of protons to form hydrogen gas. This competitive process takes place because of the relatively modest cathode potential required for hydrogen evolution. Moreover, some catalysts can shift the potential needed for the evolution of hydrogen into the region of the catalytic reduction of carbon dioxide, thereby decreasing the efficiency for the desired process involving carbon dioxide. This problem was... 

Several groups have been successful at the catalytic conversion of carbon dioxide, hydrogen, and alcohols into alkyl formate esters using neutral metal - phosphine complexes in conjunction with a Lewis acid or base (109). Denise and Sneeden (110) have recently investigated various copper and palladium systems for the product of ethyl formate and ethyl formamide. Their results are summarized in Table II. Of the mononuclear palladium complexes, the most active system for ethyl formate production was found to be the Pd(0) complex, Pd(dpm)2, which generated 10/imol HCOOEt per /rniol metal complex per day. It was anticipated that complexes containing more than one metal center might aid in the formation of C2 products however, none of the multinuclear complexes produced substantial quantities of diethyl oxalate. 

Hydrogenation of carbon dioxide to methanol was investigated over Cu/ZnO catalysts prepared by mechanical alloying(MA) method, which is suitable for excellent mixing of different materials to make alloys or composites. The catalytic activity increases with mechanical milling time, and methanol yield over the catalyst milled for 120 hour is about 1.5 times higher than that of conventional coprecipitated Cu/ZnO catalyst. The reason for increasing catalytic activity by MA method can be attributed to the preparation of well mixed structure of Cu and ZnO nanocrystals. 

Pd2Cu2Cl6(Ph2PCH2PPh2)3]. Three general reviews of catalytic reactions of carbon dioxide " " and one review on its reactions with hydrogen " are available. 

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,... 

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