Elevated temperature pressure swing adsorption process for reactive separation of CO/CO2 in H2-rich gas

Purification of CO and CO₂ to the ppm level in H₂-rich gas without losing H₂ is one of the technical difficulties for fuel cell power systems. In this work, a two-column seven-step elevated temperature pressure swing system with high purification performance was proposed. The concept of reactive separation by adding water gas shift catalysts into the columns filled with elevated temperature CO₂ adsorbents was adopted. The H₂ recovery ratio and H₂ purity were greatly improved by the introduction of steam rinse and steam purge, which could be realized due to the increasing operating temperature (200–450 °C). An optimized operating region to both achieve high efficiency and low energy consumption was proposed. The optimized case with 0.09 purge-to-feed ratio and 0.15 rinse-to-feed ratio could achieve 99.6% H₂ recovery ratio and 99.9991% H₂ purity at a stable state for a feed gas containing 1% CO, 1% CO₂, 10% H₂O, and 88% H_2. No performance degradation was observed for at least 1000 cycles. The proposed (ET-PSA) system possessed self-purification ability while the columns were penetrated by CO₂. It is however suggested that periodical heat regeneration should be adopted to accelerate performance recovery during long-term operation.