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 (H-2) for chemical production or power generation. Catalytic membrane reactor with a H-2 perm-selective membrane can improve WGS reaction conversion and separate H-2 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 3 mu m ZSM-5 layer, a 8 mu m silicalite base layer and a 2 mu m YSZ barrier layer supported on alpha-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 degrees C and under 5 atm with the H2O/CO ratio of 3.0 and GHSV of 72,000 h(-1), the CO conversion and H-2 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 degrees C, feed pressure of 20 atm, H2O/CO ratio of 2.0, GHSV of 60,000 h(-1)) under which one can achieve both high CO conversion (>95%) and H-2 recovery (>90%) for WGS in this zeolite membrane reactor. (C) 2015 Elsevier B.V. All rights reserved.