Metal-support effects on the intramolecular selectivity of crotonaldehyde hydrogenation over platinum

An overview of the catalytic properties of intermetallic compounds has been made to provide a comprehensive understanding regarding (1) what intermetallic catalysts can do, (2) their fundamental roles in enhanced catalysis, and (3) their advantages over other inorganic materials. A number of chemical transformations using intermetallic catalysts have been surveyed and classified into three major divisions—hydrogenation/dehydrogenation, oxidation, and steam reforming and various subsections. The fundamental roles of intermetallic phases obtained from this survey were categorized into four types of effects: (a) electronic, (b) geometric, (c) steric, and (d) ordering effects. The unprecedented steric effects governed by the specific surface structures of intermetallic compounds highlight the unique capabilities of intermetallic materials. On the basis of this overview, we have concluded that intermetallic compounds have the following advantages for fine catalyst design: (i) control of the electronic structur...

Intermetallic Compounds: Promising Inorganic Materials for Well-Structured and Electronically Modified Reaction Environments for Efficient Catalysis

Numerous studies concerning the hydrodesulfurization of crude oil have already been realized and have shown that substituted dibenzothiophenes, and especially the 4-methyldibenzothiophene and the 4,6-dimethyldibenzothiophene are refractory molecules of the process. The reaction mechanism of their transformation is still discussed. In this work, we have chosen to carry out the transformation of dibenzothiophene and 4-methyldibenzothiophene on various catalysts and under different experimental conditions. Attention has been particularly paid to the effect of H 2 S on the two different reaction pathways: the DDS (direct desulfurization) and the HDS (hydrogenation followed by hydrogenolysis) routes. The relative importance between the two routes is greatly modified by the presence of H 2 S: the DDS route appears to be more inhibited by this compound. An original approach to hydrodesulfurization, the competitive catalytic reaction kinetics, was also used in this study: it demonstrates that the dibenzothiophene and the 4-methyldibenzothiophene have the same adsorption equilibrium constant and suggests that the molecules are adsorbed flat on the catalyst surface. The lower reactivity of the 4-methyldibenzothiophene can then be due to a steric hindrance of the methyl group during the approach of the hydrogen molecule for the hydrogenolysis reaction.

Jean Eugène Germain

Papers

High-pressure competitive hydrogenation of ketones on copper chromite catalyst