Low-temperature Cu/Zn/SBA-16 integrating carbon membrane reactor for hydrogen production and high CO conversion through water-gas shift reaction

The increasing demand for H2 energy has led to a great amount of research being conducted in a membrane reactor (MR), in which a membrane is applied during the water-gas shift (WGS) reaction. In this study, Cu/Zn/SBA-16 WGS catalysts and carbon molecular sieve (CMS) membranes were integrated into CMS MRs. To improve the CO conversion and H2 yield, C MRs were investigated, and different steam/CO (S/C) ratios were used to evaluate the conversion performance. In this study, a tubular CMS membrane was used as the membrane material for a MR. The as-prepared CMS membrane exhibited excellent selectivity of 185.64 for H2 and CO2 mixed gas, and an ideal H2 permeability of 9.7 × 10−9 mol m−2 s−1 Pa−1 when operated under low temperature/pressure conditions (300 °C/3 bar). The Cu/Zn/SBA-16 catalyst synthesized via coprecipitation was used in the WGS reaction. With a relatively low reaction temperature of 300 °C, 2500 h−1 gas hourly space velocity, and S/C equal to 1.5, the CO conversion efficiency of MR could reach up to 99%, and the recovery of H2 was approximately 76%. However, as the S/C increased to 2, the H2 recovery increased to 99%, whereas the CO conversion decreased to 89% because of the water vapor adsorbed on the active site. The hydrophobic Si/C-modified membrane was further synthesized and showed outstanding performance in CO conversion of over 99% with S/C equal to 2.