Activation of Ethane in the Presence of Solid Acids: Sulfated Zirconia, Iron- and Manganese-Promoted Sulfated Zirconia, and Zeolites

Abstract

Ethane was activated in the presence of solid acids [sulfated zirconia (SZ), iron- and manganese-promoted sulfated zirconia (FMSZ), HZSM-5, and USY zeolite] at 1 atm, 200–450°C, and ethane partial pressures in the range 0.01–0.2 atm. The data were measured with a flow reactor at low conversions (<0.005) such that reaction of ethane took place in the near absence of alkenes. Catalysis was demonstrated for ethane conversion in the presence of FMSZ at 450°C and 0.2 atm ethane partial pressure, but the reactions were not shown to be catalytic for the other solid acids and other conditions. FMSZ was active for converting ethane into methane, ethene, and butane at an ethane partial pressure of 0.2 atm and at temperatures of 200–300°C; the other solid acids had no detectable activities under these conditions. At higher temperatures, each of the solid acids was active for conversion of ethane into ethene; butane and methane were also formed in the presence of FMSZ, HZSM-5, and USY zeolite, whereas methane was the only other hydrocarbon observed in the presence of SZ. The initial (5 min on stream) selectivities to ethene at approximately 0.1% conversion, ethane partial pressure of 0.2 atm, and 450°C were approximately 98, 94, 97, and 99%, for SZ, FMSZ, HZSM-5, and USY zeolite, respectively. Under the same reaction conditions, the initial rates of ethane conversion were 0.15×10−8, 3.5×10−8, 3.9×10−8, and 0.56×10−8mol/(s·g) for SZ, FMSZ, HZSM-5, and USY zeolite, respectively. The reactivities are consistent with chemistry analogous to that occurring in superacidic solutions and with the suggestion that FMSZ is a stronger acid than the others investigated here.