Hydrogen production from coal-derived syngas using a catalytic membrane reactor based process

Abstract

IGCC coal plants show promise for environmentally benign power generation. In these plants coal is gasified into syngas, which is then processed in a water-gas shift (WGS) reactor to further enhance its hydrogen content for power generation. However, impurities in the syngas, primarily H 2S, are detrimental to catalyst life and must be removed before the gas enters the WGS reactor. This, today, means cooling the syngas for clean-up and then reheating it to the WGS reaction temperature. For use in various industrial applications, and potentially for CO 2 capture/sequestration, hydrogen purification is required. This, today, is accomplished by conventional absorption/desorption processes, which results in significant process complexity and energy penalty for the overall plant. Ideally, one would like to establish a “one-box” process in which the syngas is fed directly into the WGS reactor, which then effectively converts the CO into hydrogen in the presence of H 2S and other impurities, and delivers a contaminant-free hydrogen product. In this study, the development of such a process is described. It includes a catalytic membrane reactor (MR) making use of a hydrogen-selective, carbon molecular sieve membrane, and a sulfur-tolerant Co/Mo/Al 2O 3 catalyst. The membrane reactor's behavior has been investigated for different experimental conditions and compared with the modeling results. The model is used to further investigate the design features of the proposed process.