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

• Tubular bilayer zeolite membrane reactor for high pressure water–gas shift.
• Highly reliable mathematic model for reaction performance prediction.
• 95% CO conversion and 90% H2 recovery achieved under optimum conditions.
• MFI zeolite membrane reactors have high potential for practical applications.

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 3 μm ZSM-5 layer, a 8 μm silicalite base layer and a 2 μm 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 5 atm with the H2O/CO ratio of 3.0 and GHSV of 72,000 h−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 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 H2 recovery (>90%) for WGS in this zeolite membrane reactor.

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