Superacids by metal oxides, X: Reaction of butane catalyzed by sulfated metal oxides, zeolites, or silica aluminas mixed with Pt–ZrO 2

Abstract

Active catalysts for the butane conversion were obtained by mechanically mixing Pt–ZrO 2 and sulfated metal oxides (SO 4–MeO x ), zeolites, or silica–aluminas. Pt–ZrO 2 was prepared by the impregnation of zirconia gel with aqueous H 2PtCl 6·6H 2O, followed by calcination at 750°C (0.5 wt.% Pt). The activity order of SO 4–MeO x was SO 4–TiO 2>SO 4–Al 2O 3>SO 4–Fe 2O 3>SO 4–SiO 2; the alumina catalyst gave the highest selectivity for the skeletal isomerization, i-C 4, 78% with 25% conversion at 220°C under the pulse reaction conditions. No effect of the Pt addition was found when prepared by co-impregnation of metal oxides with sulfate and Pt materials. The effect of mixing with zeolites and silica–aluminas showed satisfactory conversions of butane. Mordenites were highly active, but the selectivity for i-C 4 was relatively low, ∼50% at 200°C. Silica–aluminas and other zeolites, ZSM-5 and Y-type, were also active at 200°C–240°C, but most of the products were cracked materials: methane, ethane, and propane. The selectivity for i-C 4 highly increased by sulfation of the silica–aluminas to >53%.