Coupling water splitting and partial oxidation of methane (POM) in Ag modified La0.8Ca0.2Fe0.94O3-δ hollow fiber membrane reactors for co-production of H2 and syngas

Abstract

The catalytic membrane reactor, a kind of process intensification technology, can enhance chemical engineering efficiencies by combining multi-steps of reaction and separation into one unit. However, the prerequisite to realize such a promising technology is the good match between reaction efficiency, transport rate and membrane stability to withstand the real reacting conditions particularly for these high temperature reactions. In this work, we showcased the development of catalytic La0.8Ca0.2Fe0.94O3-δ-0.05Ag (LCF-Ag) hollow fiber membrane reactor to couple water splitting and partial oxidation of methane (POM) for simultaneous H2 and syngas production. Without addition of extra catalyst, LCF-Ag membrane provides the best H2 production rates (fluxes) from thermal water splitting of 3.6 and 0.69 mL min-1 cm-2 by coupling hydrogen or methane oxidation at 950 °C to consume the permeated oxygen, respectively. Noteworthy that H2 flux, methane conversion and CO selectivity is closely correlated with the presence of catalyst and operating conditions. By integrating the Ni/LaNiO3/γ-Al2O3 catalytic layer in the lumen surface to improve the POM reaction kinetics, the optimized LCF-Ag hollow fibre membrane reactor could give the best H2 flux of 7.9 mL min-1 cm-2, CH4 conversion of 58% and CO selectivity of 89%, respectively. The membrane reactor was stably operated at 950 °C for more than 20 h without failure. These results are compared favorably with literature, encouraging more future exploration to further improve membrane reactor performance for practical applications.