Stable Equilibrium Shift of Methane Steam Reforming in Membrane Reactors with Hydrogen-selective Silica Membranes

摘要

Equilibrium shifts of methane steam reforming in membrane reactors consisting of either tetramethoxysilane-derived amorphous hydrogen-selective silica membrane and rhodium catalysts, or hexamethyldisiloxane-derived membrane and nickel catalysts is experimentally demonstrated. The hexamethyldisiloxane-derived silica membrane showed stable permeance as high as 8 x 10~(-8) mol m~(-2) s~(-1) Pa~(-1) of H2 after exposure to 76 kPa of vapor pressure at 773 K for 60 h, which was a much better performance than that from the tetramethoxysilane-derived silica membrane. Furthermore, the better silica membrane also maintained selectivity of H2/N2 as high as 10~3 under the above hydrothermal conditions. The degree of the equilibrium shifts under various feedrate and pressure conditions coincided with the order of H2 permeance. In addition, the equilibrium shift of methane steam reforming was stable for 30 h with an SIC ratio of 2.5 at 773 K using a membrane reactor integrated with hexamethyldisiloxane-derived membrane and nickel catalyst.