Hydrogen-selective zeolite membrane reactor for low temperature water gas shift reaction

Hydrogen-selective zeolite membranes loading with CuO/ZnO/Al₂O₃ commercial catalysts were employed for low-temperature water gas shift (LT-WGS) reaction. The membranes were prepared by modifying zeolitic pores of MFI zeolite membranes with catalytic cracking deposition of methyldiethoxysilane. The membranes were tested by the separation of H₂/CO₂ mixture, which showed a high H₂/CO₂ separation factor of 42.6 with H₂ permeance of 2.82×10^-7mol/m²sPa at 500°C. Both the packed-bed and membrane reactors for LT-WGS were investigated by variation of temperature (T), space velocity (GHSV), steam-to-CO feed ratio (RH2O/CO) and sweep gas flow rate (FN2). Significant increment in CO conversion for the membrane reactor was achieved at relatively low temperature, high space velocity and low steam-to-CO ratio due to the large deviation from equilibrium state. High CO conversion of 95.4% was achieved in membrane reactor under the operation conditions (T=300°C, GHSV=1500L_N/kg_cath, RH2O/CO=1.25 and FN2=20cm3(STP)/min), which was higher than the equilibrium conversion. These results indicated that the membrane reactor had better performance for LT-WGS in eliminating CO.