CO₂ Capture by temperature swing adsorption: use of hot CO₂-rich gas for regeneration

Temperature swing adsorption (TSA) is an attractive technology for CO₂ removal from gas streams. CO₂ capture by a TSA process in which the recovered CO₂ product is heated and used as regeneration purge gas has been examined. Our study is based on cyclic experiments performed on a single adsorption column packed with the commercially available zeolite NaUSY adsorbent. The commercial Aspen adsorption simulator was used to simulate the experimental system, where the model predictions agreed quite well with experimental results in terms of breakthrough and results for cycle designs based on indirect heating followed by hot product gas purge. The validated model was used to simulate the case of regeneration using only hot product gas purge, which was difficult to examine experimentally due to constraints of the experimental system used. With a three-step cycle of (1) adsorption, (2) hot gas purge, and (3) cooling, this case yielded product purities of >91% CO₂ and maximum recoveries of 55.5, 76.2, and 83.6% at specific (thermal) energy consumptions of 3.4, 3.8, and 4.5 MJ/kg of CO₂ for regeneration temperatures of 150, 200, and 250 °C, respectively. Calculated productivities also varied from 0.024, 0.037, and 0.047 kg_CO2/kg_ads·h for the various regeneration temperatures. Incorporation of a product CO₂ purge prior to desorption with hot CO₂ purge gas increased the purity to 96% at a recovery of 90.8%¯these conditions are suitable for CO₂ sequestration.