Applicability of membrane reactor for WGS coal derived gas processing: Simulation-based analysis

Gas from coal gasification contains less hydrogen than from other syngas production methods. An attractive option is its further hydrogen enrichment for pure hydrogen production in a membrane reactor (MR) by water gas shift (WGS). The goal of the present study was to analyse MR fed with coal derived gas. Simulations for feasible membrane permeation parameters revealed that to get high conversion above 90% a relatively high S/C should be applied. Moreover, hydrogen recovery is in this case low (below 30%) so for hydrogen production an additional H2 separation after the MR should have been applied. The paper also shows that a clear advantage of counter- over co-current flow configuration in MR appears only for low pressure in the reaction zone. The realistic feasible Pd–Cu–Ni membrane parameters result in a rather large membrane area, thus possible heat exchange between the reaction and permeation zone can have important influences on temperature profiles in the MR. This cooling effect could lessen excessive temperature increase in the reaction zone. Results for other than single step MR configurations are also presented in the paper. It is stated in conclusion that future successful application of MRs for coal-derived gas depends on development of not only new catalysts with adequately wide operational temperature range, but also membranes with a high enough permeability.