Performance comparison of PAU and NaX zeolites in air purge–assisted low-grade heat–driven CO2 capture TSA and process configuration for high enrichment and high recovery ratio

• PAU-type zeolite was developed for an internally cooled/heated CO 2 recovery process. • CO 2 recovery from dry simulated flue gas was studied using PAU and 13X zeolites. • A simple TSA operation at 20 °C–80 °C achieved 70 % CO 2 purity with PAU zeolite. • TSA recirculation mode enabled PAU to achieve 80 % CO 2 purity and 70 % recovery. • TSA two-stage adsorption improved PAU to 93 % CO 2 purity and 75 % recovery. This study investigates an innovative paulingite (PAU) zeolite synthesized for low-temperature heat regenerative temperature swing adsorption. The PAU and commercial 13X zeolite were individually packed into a fin–coil heat exchanger with internal heating and cooling to evaluate CO 2 recovery from an adsorption inlet gas containing 10 % CO 2 balanced with nitrogen. Under a temperature swing range of 20 ℃–80 ℃ and a simple adsorption–desorption mode, the product gas achieved 56 % CO 2 purity (70 % recovery ratio) with PAU and 52 % CO 2 purity (64 % recovery ratio) with 13X at moderate regeneration purge air flow rates. The desorption-time profiles revealed that PAU is well-suited for two-stage adsorption and recirculating processes. The recirculating process increased CO 2 purity from 56 % in simple adsorption–desorption to 80% without reducing the recovery ratio (70 %). Optimizing the purge air flow rates—reducing the flow during the first desorption step and applying a moderate flow in the second step—increased CO 2 concentration with minimal impact on recovery. Through two-stage adsorption, the CO 2 purity of the produced gas reached 93 % (75 % recovery ratio). In addition, desorption without regeneration purge air for approximately three minutes at the start is recommended for PAU to minimize regeneration purge air in the product gas.