Tubular dual-layer MFI zeolite membrane reactor for hydrogen production via the WGS reaction: Experimental and modeling studies

Water-gas shift (WGS) reaction is an important intermediate step in converting fossil fuels to hydrogen (H₂) for chemical production or power generation. Catalytic membrane reactor with a H₂ perm-selective membrane can improve WGS reaction conversion and separate H₂ from carbon dioxide (CO₂) simultaneously. In this work, experimental work and modeling analysis were performed on WGS in a tubular ZSM-5/silicalite bilayer membrane composed of a 3μm ZSM-5 layer, a 8μm silicalite base layer and a 2μm YSZ barrier layer supported on α-alumina substrate. The experimental and modeling studies demonstrated that temperature, H₂O/CO ratio, gas hourly space velocity (GHSV) and feed pressure are key factors that determine the WGS performance in the tubular zeolite membrane reactor. At 500°C and under 5atm with the H₂O/CO ratio of 3.0 and GHSV of 72,000h^-1, the CO conversion and H₂ recovery reached 89.8% and 28.5%, respectively. Appropriate temperature, pressure, H₂O/CO ratio and GHSV are crucial to obtain high reaction performance. Modeling analysis coupled with experimental data identifies the optimum operation conditions (550°C, feed pressure of 20atm, H₂O/CO ratio of 2.0, GHSV of 60,000h^-1) under which one can achieve both high CO conversion (>95%) and H₂ recovery (>90%) for WGS in this zeolite membrane reactor.