Methylcyclopentane hydrogenolysis on EuroPt-1 (Pt/SiO 2), EuroPt-3 (Pt/Al 2O 3) and EuroPt-4 (PtRe/Al 2O 3) catalysts

Abstract

Modifications of the properties of platinum towards methylcyclopentane (mcp) hydrogenolysis due to a change of support from silica to alumina and the association with rhenium are measured and discussed. Only ring opening products are observed on EuroPt-1 and EuroPt-3, whereas on EuroPt-4 more than 10% cyclopentane coming from demethylation is measured. A significant effect of the reaction conditions on the product distribution is observed on EuroPt-1 and EuroPt-3 but not on EuroPt-4. The activity exhibits a maximum value as a function of hydrogen pressure and increases monotonically with increasing mcp pressure on all the studied catalysts. The apparent activation energy changes according to the sequence: EuroPt-3 ≈ EuroPt-4 < dechlorinatedEuroPt-3 < EuroPt-1, at a given reactant composition. Kinetic simulation shows that the difference in enthalpy of the reaction steps preceding the rate determining one on the different catalysts only plays a minor role in such a sequence. The low activation energy observed on the alumina supported catalysts has been attributed to the presence of chlorine on the support, which may modify the catalytic properties of metal sites due to the formation of electron-deficient platinum particles.