Superacids by metal oxides, X: Reaction of butane catalyzed by sulfated metal oxides, zeolites, or silica aluminas mixed with Pt–ZrO2 Original Research Article

Active catalysts for the butane conversion were obtained by mechanically mixing Pt–ZrO2 and sulfated metal oxides (SO4–MeOx), zeolites, or silica–aluminas. Pt–ZrO2 was prepared by the impregnation of zirconia gel with aqueous H2PtCl6·6H2O, followed by calcination at 750°C (0.5 wt.% Pt). The activity order of SO4–MeOx was SO4–TiO2>SO4–Al2O3>SO4–Fe2O3>SO4–SiO2; the alumina catalyst gave the highest selectivity for the skeletal isomerization, i-C4, 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-C4 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-C4 highly increased by sulfation of the silica–aluminas to >53%.