Design and operation of CO2-H2 multi-component separation vacuum pressure swing adsorption process with tandem-column adsorber

Vacuum pressure swing adsorption (VPSA) is a practical option for the separation of CO₂ from various waste gases with a moderate purity required for CO₂ utilization processes. In this study, the performance of the CO₂-H₂ multi-component separation VPSA process, which simultaneously separates CO₂ and H₂ in one cycle of VPSA with tandem adsorption columns, was evaluated experimentally. This process exploits unique characteristics of both the multi-component breakthrough of the feed gas components and the time variation of the desorbed gas composition to realize a simple operation for separating CO₂ and H₂ by gas fractionation. In laboratory VPSA experiments, CO₂ and H₂ separation performance was compared under various operating conditions and designs, including the feed gas volume, adsorption pressure, gas fraction time, type of adsorbent, and column length. From the experiments, the trade-off relationships of the purity of CO₂ and H₂ against recovery of CO₂ and H₂ was revealed. Furthermore, the controllability of CO₂ and H₂ purities was confirmed by changing the operating conditions and design. In a comparison with three different adsorbents changing the column length, it was found that 13X zeolite in a longer column allows effective removal of N₂.