Hydrogen production from coal-derived syngas undergoing high-temperature water gas shift reaction in a membrane reactor

In this study, a numerical model to predict the hydrogen production from water-gas shift reaction using coal-derived syngas as a feedstock was presented. The reaction was carried out in a palladium (Pd)-based membrane reactor operated at 900°C for yielding carbon monoxide (CO) conversion higher than the thermodynamic equilibrium limit. The sweep gas flow, membrane permeance, and steam-to-carbon ratio effects on the reactor performance were examined. Based on the obtained results, it was found that high CO conversion and hydrogen (H₂) recovery were obtained when the reactor was operated in counter-flow mode and with high sweep gas flow rate, steam-to-carbon ratio, and membrane permeance. However, the H₂S-to-H₂ ratio in the reactor was found to increase with the CO conversion and can be higher than the thermodynamic limit for Pd sulfidization. Optimum operation parameters should be sought for obtaining high CO conversion and H₂ recovery while preventing membrane failure due to Pd sulfidization.