Remarkable Improvement in Hydrogen Recovery and Reaction Efficiency of a Methanol Reforming−Membrane Reactor by Using a Novel Knudsen Membrane

Abstract

When a methanol reforming-membrane reactor is employed as a hydrogen generator for a proton exchange membrane fuel cell, we should simultaneously achieve three important aims in one process: methanol conversion improvement, high hydrogen recovery, and high CO removal efficiency. In this paper, the three important aims were successfully achieved in one process by using a methanol reforming-mesoporous membrane reactor combined with water gas shift (WGS) reaction. In this case, higher permeance of the membrane leads to higher hydrogen recovery and methanol conversion. Therefore, we synthesized a stainless-steel-supported Knudsen membrane with remarkably high permeability via the dipping-rolling-freezing-fast drying and soaking-rolling-freezing-fast drying method. Using the stainless-steel-supported Knudsen membrane in a methanol reforming-mesoporous membrane-WGS (MMeW) reactor, hydrogen recovery was 78-79%, and methanol conversion increased by 14-20% in comparison with a conventional reactor without a membrane. Moreover, CO permeated through the Knudsen membrane was successfully eliminated via the WGS reaction in the permeate side of the MMeW reactor.