Adsorption of CS2 and n-butylamine to characterize platinum over zirconia promoted by oxoaniones

MARISA G. FALCO; JAVIER M. GRAU; NORA S. FÍGOLI

San Luis, Argentina

Workshop; Workshop on Molecular and Particle Processes at Solid Surfaces; 2004

The adsorption of CS2 and n-butylamine were used to characterize platinum over zirconia promoted by tungsten oxide or sulfate. Two test reactions were used: 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 further 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. For both reactions the adsorption of CS2 and n-butylamine poisons the two catalysts. They are 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. The adsorption studies allowed to determine that the isomerization reaction occurs through a non classical bifunctional mechanism.