Simulation of 12-bed vacuum pressure-swing adsorption for hydrogen separation from methanol-steam reforming off-gas

This study focuses on analysis of a 12-bed vacuum pressure-swing adsorption (VPSA) process capable of purifying hydrogen from a ternary mixture (H-2/CO2/CO 75/24/1 mol%) derived from methanol-steam reforming. The process produces 9 kmol H-2/h with less than 2 ppm and 0.2 ppm of CO2 and CO, respectively, to supply a polymer electrolyte membrane fuel cell. The process model is developed in Aspen Adsorption (R) using the uni-bed approach. A parametric study of H-2 purity and recovery with respect to adsorption pressure, adsorbent height, activated carbon:zeolite ratio, feed composition, and number of beds is performed. Results show 12-bed VPSA can meet the H-2 purity goals, with H-2 recovery as high as 75.75%. Adsorption occurs at 7 bar, the column height is 1.2 m, and the adsorbent ratio is 70%:30%. A 4-bed VPSA can achieve the same purity goals as the 12-bed process, but H-2 recovery decreases to 61.34%. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study focuses on analyzing a 12-bed vacuum pressure-swing adsorption (VPSA) process for purifying hydrogen from a ternary mixture derived from methanol-steam reforming. Results show that the 12-bed VPSA process can achieve high purity hydrogen production with a recovery rate of up to 75.75%, while a 4-bed VPSA process can achieve the same purity goals but with a lower hydrogen recovery rate.