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MgO-based sorbents were prepared by impregnation with K2CO3 at different loadings. This study examined the CO2 absorption and regeneration properties of MgO-based sorbents at various pressures. The CO2 capture capacity of the PMI-30 sorbent increased to 204.4 mg CO2/g sorbent with increasing absorption pressure through CO2 absorption by MgO itself and K2CO3 by generating structures, such as MgCO3·3H2O and K2Mg(CO3)2. However, no KHCO3 phase was observed after CO2 absorption at 1, 10, and 20 atm. The CO2 capture capacity of the MgO and PMI-10, 20, 30, and 40 sorbents was the 94.6, 129.9, 156.6, 204.4, and 239.4 mg CO2/g sorbent, respectively. The CO2 capture capacity of MgO in the PMI sorbent was relatively constant regardless of the decreasing MgO content and increasing K2CO3 content. The CO2 absorption ability of MgO was calculated by substracting theoretical CO2 capture capacity of K2CO3 from the total capacity of sorbents. The TPD experiment performed at 1 atm after CO2 absorption at 20 atm showed that the regeneration temperature of the PMI sorbents differed according to the K2CO3 loading. [ABSTRACT FROM AUTHOR]