Propane Conversion Catalyzed by Sulfated Zirconia, Iron- andManganese-Promoted Sulfated Zirconia, and USY Zeolite

Abstract

Solid acid catalysts, namely sulfated zirconia, iron- andmanganese-promoted sulfated zirconia, and USY zeolite, weretested for conversion of propane at 1 atm, 200–450°C, andpropane partial pressures in the range 0.01–0.05 atm. Bothpromoted and unpromoted sulfated zirconia were found to beactive for conversion of propane into butanes, pentanes,methane, ethane, ethylene, and propylene in the temperaturerange 200–350°C, but catalyst deactivation was rapid. Atthe higher temperatures, only cracking and dehydrogenation productswere observed. In contrast to the zirconia-supported catalysts,USY zeolite was observed to convert propane (into propylene,methane, and ethylene) only at temperatures ≥400°C. The initial (5 min on stream) rates of propane conversion in the presence ofiron- and manganese-promoted sulfated zirconia, sulfatedzirconia, and USY zeolite at 450°C and 0.01 atm propanepartial pressure were 3.3×10−8, 0.3×10−8, and 0.03×10−8mol/(s·g), respectively. Theproduct distributions in the temperature range 200–450°Care those of acid–base catalysis, being similar to what has beenobserved in superacid solution chemistry at temperatures <0°C. Ifpropane conversion at 450°C can be considered as a probeof acid strength of the catalyst, then the activity comparisonsuggests that the promoted sulfated zirconia is a stronger acidthan sulfated zirconia, which is a stronger acid than USY zeolite.