Adsorptive cyclic purification process for CO₂ mixtures captured from coal power plants

CO₂capture technology combined with bulk separation and purification processes has become an attractive alternative to reduce capture costs. Furthermore, the required purity in the application for CO₂conversion and utilization is more stringent than that required from a captured CO₂mixture for geological storage. In this study, an adsorptive cyclic purification process was developed to upgrade a CO₂/N₂mixture captured from greenhouse gas emission plants as a feasibility study for a second capture unit or captured CO₂purifier. To purify 90% CO₂with balance N₂as a captured gas mixture, two-bed pressure swing adsorption and pressure vacuum swing adsorption (PVSA) processes using activated carbon were experimentally and theoretically studied at adsorption pressures of 250–650 kPa and a fixed vacuum pressure of 50 kPa. CO₂with higher than 95% purity was produced with more than 89% recovery. However, a four-bed PVSA process could successfully produce CO₂with greater than 98% purity and 90% recovery.