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

CO2 capture 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 CO2 conversion and utilization is more stringent than that required from a captured CO2 mixture for geological storage. In this study, an adsorptive cyclic purification process was developed to upgrade a CO2/N-2 mixture captured from greenhouse gas emission plants as a feasibility study for a second capture unit or captured CO2 purifier. To purify 90% CO2 with balance N-2 as 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. CO2 with higher than 95% purity was produced with more than 89% recovery. However, a four-bed PVSA process could successfully produce CO2 with greater than 98% purity and 90% recovery. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 1051-1063, 2017