Catalytic Properties of Silica-Supported Tantalum and Tungsten Hydrides in the Cleavage and Formation of C-C Bonds of Alkanes

摘要

Heterogeneous catalysts are widely used in industrial applications; they are often easily prepared at a low cost and can be conveniently separated from the reaction medium. However it is always difficult to define and control the active site and then to determine the various elementary steps of a catalytic reaction. On the contrary, homogeneous catalysis has been based on the rules of molecular organometallic chemistry, which affords a better understanding of what are the active species and the elementary steps of a process. Surface Organometallic Chemistry (SOMC) is aimed at the prelparation of a new type of heterogeneous catalysts for which the concepts and the rules of molecular organometallic chemistry could be transposed. The reaction of molecular complexes with functional groups of a surface affords the formation of highly reactive well-defined supported organometallic species, usualy unprecedented in solution.