Kinetics of liquid-phase hydrogenation reactions over supported metal catalysts - a review

The kinetics of liquid-phase hydrogenation reactions have been reviewed wit h a special emphasis on or, beta -unsaturated aldehydes as reactants. These reactions can be complex and can be influenced by factors such as metal sp ecificity, side reactions, and metal-support interactions as well as reacti on parameters. The importance of results in the absence of heat and mass tr ansfer limitations has been emphasized. Hydrogenation reactions are typical ly assumed to be structure-sensitive, but dependencies on metal crystallite size have been reported; however, this behavior has been attributed to sid e reactions which can inhibit activity. Finally, solvent effects can exist, but the effect of H-2 concentration in the liquid phase has infrequently b een isolated. Thermodynamic arguments indicate that a solvent effect can en hance the surface coverage of hydrogen on the catalyst surface at a constan t H-2 partial pressure, but in the absence of any solvent effects, surface coverage is independent of the liquid-phase H-2 concentration. (C) 2001 Els evier Science B.V. All rights reserved.