Propane conversion catalyzed by sulfated zirconia, iron- and manganese-promoted sulfated zirconia, and USY zeolite

Solid acid catalysts, namely sulfated zirconia, iron- and manganese-promoted sulfated zirconia, and USY zeolite, were tested for conversion of propane at 1 atm, 200-450 degrees C, and propane partial pressures in the range 0.01-0.05 atm. Both promoted and unpromoted sulfated zirconia were found to be active for conversion of propane into butanes, pentanes, methane, ethane, ethylene, and propylene in the temperature range 200-350 degrees C, but catalyst deactivation was rapid, At the higher temperatures, only cracking and dehydrogenation products were observed. In contrast to the zirconia-supported catalysts, USY zeolite was observed to convert propane (into propylene, methane, and ethylene) only at temperatures greater than or equal to 400 degrees C, The initial (5 min on stream) rates of propane conversion in the presence of iron- and manganese-promoted sulfated zirconia, sulfated zirconia, and USY zeolite at 450 degrees C and 0.01 atm propane partial pressure were 3.3 x 10(-8), 0.3 x 10(-8), and 0.03 x 10(-8) mol/(s . g), respectively. The product distributions in the temperature range 200-450 degrees C are those of acid-base catalysis, being similar to what has been observed in superacid solution chemistry at temperatures < 0 degrees C. If propane conversion at 450 degrees C can be considered as a probe of acid strength of the catalyst, then the activity comparison suggests that the promoted sulfated zirconia is a stronger acid than sulfated zirconia, which is a stronger acid than USY zeolite. (C) 1996 Academic Press, Inc.