Modeling study on a two-stage hydrogen purification process of pressure swing adsorption and carbon monoxide selective methanation for proton exchange membrane fuel cells

Abstract

A two-stage hydrogen purification process based on pressure swing adsorption (PSA) and CO selective methanation (CO-SMET) is proposed to meet the stringent requirements of H2-rich fuel for kW-scale skid-mounted or distributed proton exchange membrane fuel cell systems. The reforming gas is purified using dynamic adsorption model of PSA with activated carbon for initial purification and then kinetic model of CO-SMET with 50 wt% Ni/Al2O3 for CO deep removal. Sensitive analyses of the gas hourly space velocity, adsorption time and adsorption pressure etc. are studied. The results show that excellent H2 purity and CO concentration below 1000 ppm for the initial target using the three-bed and four-bed PSA system at shorter adsorption time and higher pressure, and then CO concentration below 10 ppm with H2 purity over 99.94% on CO-SMET. This work provides a small-scale and hydrogen-saving process for hydrogen purification can be achieved by the two-stage process.