Potassium-Promoted Limestone for Preferential Direct Hydrogenation of Carbonates in Integrated CO<sub>2</sub> Capture and Utilization
Shuzhuang Sun, Zheng Chen, Yikai Xu, Yuanyuan Wang, Yingrui Zhang, Catherine Dejoie, Shaojun Xu, Xin Xu, Chunfei Wu
Abstract
High Resolution Image Download MS PowerPoint Slide Integrated CO 2 capture and utilization (ICCU) via the reverse water–gas shift (RWGS) reaction offers a particularly promising route for converting diluted CO 2 into CO using renewable H 2 . Current ICCU-RWGS processes typically involve a gas–gas catalytic reaction whose efficiency is inherently limited by the Le Chatelier principle and side reactions. Here, we show a highly efficient ICCU process based on gas–solid carbonate hydrogenation using K promoted CaO (K-CaO) as a dual functional sorbent and catalyst. Importantly, this material allows ∼100% CO 2 capture efficiency during carbonation and bypasses the thermodynamic limitations of conventional gas-phase catalytic processes in hydrogenation of ICCU, achieving >95% CO 2 -to-CO conversion with ∼100% selectivity. We showed that the excellent functionalities of the K-CaO materials arose from the formation of K 2 Ca(CO 3 ) 2 bicarbonates with septal K 2 CO 3 and CaCO 3 layers, which preferentially undergo a direct gas–solid phase carbonates hydrogenation leading to the formation of CO, K 2 CO 3 CaO and H 2 O. This work highlights the immediate potential of K-CaO as a class of dual-functional material for highly efficient ICCU and provides a new rationale for designing functional materials that could benefit the real-life application of ICCU processes.