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

Abstract

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 (CO 2) 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, H 2 O/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 o C and under 5 atm with the H 2 O/CO ratio of 3.0 and GHSV of 72000 h-1 , the CO conversion and H 2 recovery reached 89.8% and 28.5%, respectively. Appropriate temperature, pressure, H 2 O/CO ratio and GHSV are crucial to obtain high reaction performance. Modeling analysis coupled with experimental data identifies the optimum operation conditions (550 o C, feed pressure of 20 atm, H 2 O/CO ratio of 2.0, GHSV of 60000 h-1) under which one can achieve both high CO conversion (>95%) and H 2 recovery (>90%) for WGS in this zeolite membrane reactor.

Zeolite Membranes in Catalysis—From Separate Units to Particle Coatings

“…Simulations proved the potential of the membrane reactor, combining a modified MFI membrane and cerium-doped ferrite catalysts, to reach CO conversion above 99.5% at 550 °C and ~50 atm at a ratio of H2O/CO ~5.0 [155]. Similarly, Lin et al [156] evaluated the performance of ZSM-5/silicalite bilayer membranes packed with Fe-Cr-Cu catalysts combining experimental and theoretical studies and defined the optimal conditions under which CO conversion of over 95% together with H2 recovery of over 90% could be achieved. For low-temperature WGS reactions, Zhang et al [153] illustrated the benefit of PBMRs coupling a H2-permselective MFI membrane modified by CCD of methyldiethoxysilane and CuO/ZnO/Al2O3 catalyst over the conventional packed bed reactor.…”

A Review on the Production and Purification of Biomass-Derived Hydrogen Using Emerging Membrane Technologies

“…Chemical vapour decomposition (CVD) and chemical cracking decomposition (CCD) are widely used to improve the performance of the ZSM-5 membrane, as these modification methods can result in an impressive improvement in H 2 /CO 2 selectivity [106][107][108][109]. Lin et al post-treated ZSM-5 membranes in two steps.…”

Advances of zeolite based membrane for hydrogen production via water gas shift reaction

“…The researches in membrane reactor have already been studied a lot via both experiments and simulations and several configurations have been proposed [29]. However, the tubular configuration is the most common with the process stream inside a tube [37,16] while the reversal configuration has also been already performed [27]. The performance of several WGS membrane reactors is summarized in Table 1.…”

“…Hasegawa et al [73] modified Y-type zeolite membranes by Pt catalyst. Pt catalyst was used to improve the CO conversion and selectivity by dispersing it in the zeolite membrane (ZSM-5) [77,20,55,16,78,79]. To further optimize the performance of zeolite membranes, composite membrane was prepared by coating an Rh-loaded C-Al 2 O 3 membrane with a defect-free SiO 2 layer hence SiO2/Rh/C-Al 2 O 3 membrane can improve the CO oxidation and the H 2 production will increase rapidly [80,81].…”

“…The process will be much simplified from two-step reaction process into a single stage shift reactor that produces high purity hydrogen without or with minimum further separation/purification step. This will also reduce the duty of the scrubbing system and high pressure CO 2 can be obtained which will minimize the cost of CO 2 capture [16]. Nevertheless, stability is one key issue of WGS membrane reactors.…”