University of Lyon, France
Title: From Material Science to Single Site Catalysis
Catalysis is the number one technology in chemical industry and petroleum refining: 95 percent of all products (volume) are synthesized by means of catalysis. The advantages of catalytic processes are due to the mild reaction conditions, their cost efficiency, and their environmentally friendly character.
Nevertheless sometimes catalysis is not selective enough, which increases products involved in green house effects (like CO2, NOx or particles). New reactions are needed (for example, methane, which is abundant in the world, is not selectively transformed into valuable products. Catalysis using bio-based raw materials will gain more and more interest for the progressive replacement of fossil fuels.
A predictive approach of catalysis is emerging due to the spectacular progresses made in the synthesis of well defined materials. The nano-control of active site via a pluridisciplinary approach is one of the ways to address this issue of catalytic "environmental" or "energy" performances. It is now possible to achieve the rational design and synthesis of well defined materials with the expected structure, acidity, porosity in the field of oxides, carbon based materials or zerovalent mono and pluri metallic particles of given size and composition. The grafting of organometallic compounds onto these materials results in the synthesis of "single site" catalysts both on oxide or metallic nanoparticules. The characterisation of the grafted organometallic complexes results from the use of a variety of techniques coming from surface science and molecular chemistry: in situ IR, in situ 1H, 13C NMR, 2D NMR, EXAFS, Surface Microanalysis, determination of the stoichiometry of surface reactions. The detailed knowledge of the structure of the active site which results from this careful determination allows one to determine elementary steps of heterogeneous catalysis and a structure activity relationship can be achieved in several cases. A new generation of catalysts, new catalytic reactions, improvement of existing catalysts, related to energy and environment have been discovered on these materials.
Examples will be given in the field of Energy, Petroleum, Environment, Chemistry: Ziegler-Natta depolymerisation, Alkane metathesis, Methane coupling to ethane, Methane-olysis of alkanes, Direct transformation of ethylene to propylene, Metathesis of olefins, Dehydrogenation of paraffins, Epoxidation of alkanes.