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 degrees 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.