CO2 sorption and reaction kinetic performance of K2CO3/AC in low temperature and CO2 concentration

• The CO2 sorption capacity of the desired K2CO3/AC was 1.015 mmol CO2/g, and the carbonation conversion was 79.0%.
• The CO2 sorption capacities of K2CO3/AC decrease as the temperature increases from 20 to 60 °C.
• The CO2 sorption performance of K2CO3/AC is enhanced with the increase in CH2O:CCO2CH2O:CCO2.
• The sorbent retains stable CO2 sorption capacity during 20 carbonation-regeneration cyclic operations.
• K2CO3/AC shows a higher utilization efficiency of active compound and a higher thermal stability.

Reducing or removing CO2 is critical to the confined spaces such as submarines, space-crafts or aircrafts while using solid sorbents has been regarded as a promising method. In this work, K2CO3 loaded on activated carbon (K2CO3/AC) was developed as a new and regenerable sorbent for CO2 removing in confined spaces. CO2 sorption performances of K2CO3/AC were investigated under different conditions by varying the K2CO3 loadings, CO2 concentrations, H2O concentrations, CO2 sorption temperatures and water pretreatment durations as well as the purge gas flow rates. The CO2 sorption capacity and carbonation conversion of K2CO3/AC decrease with increasing temperature and increase with increasing mole ratio of H2O concentration over CO2 concentration. Sufficient water vapor pretreatment is found to be beneficial to the sorption-enhanced performance. Increasing flow rate will weaken the CO2 sorption performance. The carbonation kinetics was also investigated with the correlation between the shrinking core model and experimental data. Additionally, the sorbent is proved to be regenerable and stable during 20-cycle CO2 sorption–desorption experiments. K2CO3/AC presents high carbonation conversion efficiency, high thermal stability, and low dependency on CO2 partial pressure. Therefore, it can be considered as a new option for CO2 removal in confined spaces.