High-purity hydrogen production via a water-gas-shift reaction in a palladium-copper catalytic membrane reactor integrated with pressure swing adsorption

Abstract

Abstract A Pd-Cu catalytic membrane reactor (CMR) integrated with pressure swing adsorption (PSA) was developed to produce fuel cell grade hydrogen from syngas. The enhanced water-gas-shift reaction in the Pd-Cu CMR packed with a high-temperature shift catalyst was experimentally conducted by using a carbon monoxide (CO)/hydrogen (H2)/carbon dioxide (CO2) mixture (65:30:5\xa0vol%) at 360–380\xa0°C, 6–10\xa0bar, and a steam/carbon (s/c) ratio of 1–5. Since H2 was used as the sweeping gas, pure H2 could be directly obtained from the permeate side. The temperature inside the packed catalysts was well distributed in the developed CMR module without any specific hotspots during the reaction and separation. The CO conversion in the CMR increased from 85.4% to 94.8% with the recovery of 53.4% to 56.1% when the s/c ratio increased from 1 to 5. The conversion rate was enhanced by 10.0–16.7% compared with the fixed catalytic bed reactor. When four-bed PSA using activated carbon and zeolite was integrated to recover more H2 from the retentate flow, the recovery of H2 was additionally improved by 31.2–35.7%. The integrated Pd-Cu CMR with four-bed PSA could produce H2 of over 99.9991% with a recovery of 91.37% and 8.67\xa0ppm CO. For H2 produced with less than 0.2\xa0ppm CO, the recovery was reduced to 85.99% with 0.15\xa0ppm CO. The feasibility of CMR with PSA to enhance CO conversion and H2 recovery is suggested for the production of fuel cell grade H2 for a proton-exchange membrane fuel cell (ISO 14687).