Purification of hydrogen by pressure swing adsorption

Pressure swing adsorption (PSA) processes are used for the production of hi gh purity hydrogen from steam methane reforming off-gas (SMROG) and refiner y off-gases (ROG). A variety of commercial PSA processes for the production of Ha with or without a by-product (CO2 from SMROG), as well as PSA proces ses for direct production of ammonia synthesis gas (from SMROG), are review ed. The equilibrium ad(de)sorption characteristics of the components of SMR OG and ROG feed gas on an activated carbon, a zeolite, and a silica gel are reported, and the criteria for adsorbent selection in these PSA processes are discussed. Recent ideas to increase the H-2 recovery from these PSA pro cesses by integrating them with selective surface flow membranes or other P SA units an reviewed.