Magnesium oxide (MgO) is recognized as a promising medium-temperature CO2 capture material, yet it suffers from inherent drawbacks of sluggish reaction kinetics and inferior cyclic stability. To address these critical challenges, a novel MgO-based sorbent synergistically modified with CaCO3, NaNO3, and LiFePO4 was developed in this study. The target sorbent was fabricated via a hybrid approach combining wet impregnation and solid-state reaction, and its physicochemical properties were comprehensively characterized using systematic analytical techniques. Under optimized conditions (340 °C, ambient pressure), the optimal sorbent MC95–Na0.2Li0.01 showed a CO2 capture capacity of 0.59 gCO2/gsorbent, nearly three times that of the NaNO3-free sample. After 20 adsorption–desorption cycles, it still maintained 0.32 gCO2/gsorbent. Compared with the CaCO3-free sample, its capacity retention increased by 36.48% and cyclic stability by ∼115%, effectively suppressing decay and demonstrating excellent CO2 capture performance. Density functional theory (DFT) calculations revealed that codoping with Na, Li, Ca, and Fe species induces significant electron transfer and strong orbital hybridization with CO2 molecules, which substantially enhances the adsorption energy in comparison with unmodified or singly doped MgO surfaces. This work not only proposes an effective strategy for the design and fabrication of high-performance MgO-based sorbents but also elucidates the electronic-level mechanism underlying doping-enhanced CO2 adsorption. This study can provide theoretical guidance and experimental support for the rational design of high-performance MgO-based adsorbents, and facilitate the engineering application of CCUS technologies in industrial waste gas treatment.
Guo et al. (Sun,) studied this question.