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 × 10−7 mol/m2 s Pa 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)(RH2O/CO) and sweep gas flow rate (FN2)(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 = 1500 LN/kgcat h, RH2O/CO=1.25RH2O/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.

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► MFI zeolite membranes were modified by catalytic cracking of MDES.
► Modified MFI zeolite membranes showed high selectivity for H2 over CO2.
► The membrane reactor for LT-WGS showed an improved CO conversion.