Carbon tetrachloride hydrodechlorination with organometallics based platinum and palladium catalysts on MgO : EXAFS characterization and catalytic studies

Hydrodechlorination of carbon tetrachloride was performed over Pd and Pt on MgO catalysts obtained from different precursors. The Pd samples show low activity and high selectivity to deep hydrogenolysis of C-Cl bonds to CH3(ads) fragments leading to C1 - C7+ hydrocarbons, following a typical Schulz-Flory distribution for alkyl polymerization. On the other hand Pt catalysts show high and stable conversion levels, but totally different selectivities. CHCl3 and in lesser extent methane are the major products. The structural modifications of Pt catalysts under reaction conditions were characterised by EXAFS spectroscopy. The amount and the nature of chlorine species preadsorbed on catalysts play an important role contributing to stabilise the properties of metallic particles.