Poisoning of platinum over zirconia promoted by oxoanions by CS2 and n-butylamine

M.G. FALCO; J.M. GRAU; N.S. FÍGOLI

Paris, Francia

Congreso; 13th International Congress on Catalysis; 2004

Platinum over zirconia promoted by tungsten oxide or sulfate were studied by test reactions: cyclohexane deshydrogenation (metallic function) and n-pentane isomerization (acid function). Both reactions were carried out at 300 °C, atmospheric pressure and in the presence of hydrogen. Catalysts were characterized by XRD, Sg, ICP-OES and DRIFTS. Benzene and methylcyclopentane were obtained during cyclohexane reaction and iso-pentane was the main product during n-pentane one. Both reactions are poisoned by CS2 and n-butylamine, typical poisons of the metal and acid functions, respectively. For the cyclohexane reaction, CS2 poisons directly the metal function and indirectly the acid function, because the hydrogen dissociation capacity of Pt is decreased. The dissociated hydrogen generates the acid sites by interaction with tungsten or sulfur containing surface groups. n-Butylamine also poisons both test reactions, but not the production of benzene from CH. These results indicate that the isomerization reactions occur through a non classical bifunctional mechanism.