Heterogeneous metal-catalyzed hydrogen

The commonly accepted mechanism of heterogeneously catalyzed hydrogenation involves activation of both the hydrogen and the C—C multiple bond adsorbed on the metal surface. First one hydrogen atom is transferred to the least hindered position of the multiple bond to give a half-hydrogenated adsorbed species. This reaction is fully reversible and ac-... 

The hydrogenation reactions occurring on heterogeneous basic catalysts have characteristic features, which distinguish heterogeneous basic catalysts from transition metal catalysts.44 The key features of the base-catalyzed hydrogenation reactions are as follows ... 

Heterogeneously catalyzed hydrogenation reactions can be run in batch, semibatch, or continous reactors. Our catalytic studies, which were carried out in liquid, near-critical, or supercritical C02 and/or propane mixtures, were run continuously in oil-heated (200 °C, 20.0 MPa) or electrically heated flow reactors (400 °C, 40.0 MPa) using supported precious-metal fixed-bed catalysts. The laboratory-scale apparatus for catalytic reactions in supercritical fluids is shown in Figure 14.2. This laboratory-scale apparatus can perform in situ countercurrent extraction prior to the hydrogenation step in order to purify the raw materials employed in our experiments. Typically, the following reaction conditions were used in our supercritical fluid hydrogenation experiments catalyst volume, 2-30 mL total pressure, 2.5-20.0 MPa reactor temperature, 40-190 °C carbon dioxide flow, 50-200 L/h ... 

The addition of hydrogen to olefins is made possible only with noble metal catalysts. They allow for a multistep, low-energy reaction pathway. The noble metal catalyst may be soluble in the reaction mixture in that case we have a homogeneously catalyzed hydrogenation (cf. Section 14.4.7). But the catalyst may also be insoluble then we deal with a heterogeneously catalyzed hydrogenation. 

General G. Centi, F. Cavani, F. Trifiro, Selective Oxidation by Heterogeneous Catalysis, Kluwer Academic/Plenum Publishers, New York, 2001 G. Ertl, H. Knotzinger, J. Weitkamp, (Eds.), Handbook of Heterogeneous Catalysis, Volume 5, Wiley-VCH, Weinheim 1997 R.A. Sheldon, J.K. Kochi, Metal Catalyzed Oxidations of Organic Compounds, Academic Press, New York, 1981 G. Strukul (Ed.), Catalytic Oxidations with Hydrogen Peroxide as Oxidant, Kluwer, Dordrecht, 1992 K. Weissermel, H.-J. Arpe, Industrial Organic Chemistry, 4th Edition, Wiley-VCH, Weinheim 2003. Epoxidations J.C. Zomerdijk, M.W. Hall, Catal. Rev. Sci. Eng., 1981, 23, 163 ... 

Reactions on Metal Surfaces Heterogeneously Catalyzed Hydrogenation and Isomerization... 

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