PROPANE CONVERSION CATALYZED BY SULFATED ZIRCONIA, IRON-PROMOTED AND MANGANESE-PROMOTED SULFATED ZIRCONIA, AND USY ZEOLITE

Solid acid catalysts, namely sulfated zirconia, iron- and manganese-pr omoted 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 zirc onia were found to be active for conversion of propane into butanes, p entanes, methane, ethane, ethylene, and propylene in the temperature r ange 200-350 degrees C, but catalyst deactivation was rapid, At the hi gher temperatures, only cracking and dehydrogenation products were obs erved. In contrast to the zirconia-supported catalysts, USY zeolite wa s observed to convert propane (into propylene, methane, and ethylene) only at temperatures greater than or equal to 400 degrees C, The initi al (5 min on stream) rates of propane conversion in the presence of ir on- and manganese-promoted sulfated zirconia, sulfated zirconia, and U SY 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), respective ly. The product distributions in the temperature range 200-450 degrees C are those of acid-base catalysis, being similar to what has been ob served 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 z irconia, which is a stronger acid than USY zeolite. (C) 1996 Academic Press, Inc.