Nonoxidative methane coupling in a SrCe0.95Yb0.05O3-α (SCYb) hollow fiber membrane reactor

SrCe0.95Yb0.05O3-alpha (SCYb) hollow fiber membranes have been prepared by an immersion induced phase inversion where polyethersulfone (PESf) is used as a binder, N-methyl-2-pyrrollidone (NMP) as a solvent, and poly( vinylpyrrolidone) (PVP( K90)) as an additive, respectively. After the membrane was properly characterized, a membrane reactor was subsequently designed with the SCYb hollow fiber for methane coupling. The performance of the hollow fiber membrane reactor in the methane coupling reaction was investigated both experimentally and theoretically. The results show that permeation of hydrogen through the membrane promotes the formations of ethylene and ethane. An increase of operating temperatures is favorable for the formation of ethylene over ethane. Due to the methane carbonization and the formation of higher hydrocarbons (C-3-C-5), the C-2 selectivity decreases as the temperature is increased. When the temperature increases to 950 degrees C, the C-2 yield is improved to a maximum of 13.4% and then decreased if the temperature is increased further. When increasing the methane feed flow rate, the ethylene formation rate is increased but the ethane production is decreased. A simple mechanism for methane coupling on the SCYb membrane is presented, with which the performance of the mixed proton conducting membrane reactor in the methane coupling reaction can be predicted reasonably well with theoretical models.