Hydrogenation of CO and

Steam reforming of CH4 CH4 + H2O = CO + 3H2 NH3 synthesis from the elements Hydrogenation of CO and CO2 to form hydrocarbons (Fischer-Tropsch syndresis)... 

The hydrogenation of CO and C02 on transition metal surfaces is a promising area for using NEMCA to affect rates and selectivities. In a recent study of C02 hydrogenation on Rh,59 where the products were mainly CH and CO, under atmospheric pressure and at temperatures 300 to 500°C it was found that CH4 formation is electrophobic (Fig. 8.54a) while CO formation is electrophilic (Fig. 8.54b). Enhancement factor A values up to 220 were... 

W-Rh IWCRht/oCOMCOljD/VCsHO ,) 193, Si02 Hydrogenation of CO and characterization of catalyst (FTIR. CO chemisorption. TPR. EPR) E)9... 

For any given catalytic reaction the active surface area is normally only a small fraction of the area of the active component (active phase). The term active sites is often applied to the sites effective for a particular heterogeneous catalytic reaction. The terms active site and active centre are often used as synonyms, but active centre may also be used to describe an ensemble of sites at which a catalytic reaction takes place. There is evidence that the centres required for some catalytic reactions are composed of a collection of several metal atoms (ensemble). This appears to be the case for such reactions as, for example, hydrogenolysis, hydrogenation of CO, and certain deuterium-exchange processes with hydrocarbons. 

The hydrogenation of CO and the formation of each individual C hydrocarbon (e.g., methane) obey Langmuir-Hinshelwood kinetic expressions (32,64,66,67.75)-. 

The progressive poisoning affecting Au, Ag and Cu cathodes during electroreduction of CO2 [16-20] renders their behaviour in some ways similar to that of the catalysts employed in the gas phase hydrogenation of CO and CO2. 

Liu, X. Recent advances in catalysts for methanol synthesis via hydrogenation of CO and C02. Industrial Engineering Chemistry Research, 2003, 42, 6518. 

D.J. Dwyer and G.A. Somorjai, Hydrogenation of CO and CO2 over Iron Foils Correlations of Rate, Product Distribution, and Surface Composition, J. Catal. 52 (1978) 291. 

Energy recovery. Synthesis gas can be used as fuel gas. In this case the presence of large amounts of methane is advantageous, which can be achieved by varying the reaction conditions in the gasifier to promote methanation reactions by hydrogenation of CO and C02. 

Synthesis of methanol by catalytic hydrogenation of CO and C02. A higher H2/CO ratio is necessary for this process, which can be obtained by promoting the water-shift reaction. 

CH4 is first oxidatively coupled to form C2H4, CO and H2, the mixture is reacted over a dual catalyst, a metal oxide for hydrogenation of CO and ZSM-5 for the oligomerization of C2H4... 

Bulk gold is generally considered to be catalytically inactive. However, recently, very small, well dispersed Au particles have been found to have high catalytic activity for various reactions. These reactions include the hydrogenation of CO and CO2 [56-58], the reduction of NO [59-61] and the oxidation of methane [62], propene and propane [63, 64]. But the most surprising results have been achieved in low temperature CO oxidation. For example Au/Ti02 and Au/Fe203 are capable of CO oxidation at room temperature [65-68]. 

An Au/Si02 catalyst was also tested but no observable conversion or products were foimd. The CO hydrogenation over Au/Zr02 produced only CHt, C2H6 and CsHs in our current system. It was reported by Baiker [11] in 1993 that methanol was synthesized over AU/Z1O2 from hydrogenation of CO and CO2. Hence, our initial results show some differences in this respect, since we observed no activity for methanol formation with Au/Zr02 under our reaction conditions. 

Next, let us take a eloser look at electronie elfeets. Potassium is used as a promoter in many eatalytic reactions. The hydrogenation of CO and ammonia synthesis are two well-known examples. The strongly electropositive potassium (or, more often, the oxide K2O) provides electrons that flow to the metal and then into the chemisorbed molecule. In this way, n backbonding into the n orbitals of the adsorbate is considerably strengthened. Figure 5-36 explains this for the example of nitrogen. 

Au particles supported on reducible oxides such as titania or ceria are also efficient catalysts for the water-gas shift, the destruction of sulfur dioxide (DeSOx processes), the complete oxidation of methane, the selective or partial oxidation of propene, the hydrogenation of CO and olefins, and the reduction of NO with hydrocarbons. Depending on the conditions, Au/TiOs... 

The Rh supported on Z1O2 exhibits higher catalytic activity for the hydrogenation of CO and CO2 compared with that supported on AI2O3, Si02, In particular,... 

The hydrogenation of CO and CO2 on transition-metal surfaces is a promising area for using NEMCA to affect rates and selectivities. In a recent study of CO2 hydrogenation on where the products were... 

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