Adsorbent Characteristic Regulation and Performance Optimization for Pressure Swing Adsorption via Temperature Elevation

Physical adsorbents are conventionally supposed to work at a normal temperature (298 K). However, elevating the working temperature can also restrain the adsorption of effective gas and may improve the adsorbent performance. Temperature variation is demonstrated to be a way to regulate the adsorbent performance. In this study, a coal-based activated carbon was synthesized and characterized. The CO2 and H-2 adsorption capacities are inversely associated with the adsorption temperature, and a larger adsorption heat does not mean a higher adsorption capacity. Although the CO2 adsorption capacity is much higher than that of H-2, sometimes the H-2 adsorption capacity is more sensitive to the temperature. The adsorption selectivity for CO, over H-2 improves when the temperature rises from 298 to 353 K A four-bed pressure swing adsorption (PSA) model was developed on the basis of an on-site pilot-scale PSA apparatus to determine the practical separation performance of adsorbents under different working conditions. The simulation results showed that, when the product gas purity is the same, the recovery rate at 353 K is approximately 2% higher than that at 298 K, indicating that the improvement in adsorption selectivity can make up for the declining adsorption capacity. More importantly, the improvement in gas recovery implies a higher energy efficiency or higher productivity. This phenomenon also exists in some other adsorbents reported before, including chemical adsorbents and composite adsorbents.