关键词: 碳捕集, 氧化乙烷脱氢, 双功能材料, 局域催化环境, C-H/C-C选择性活化

Abstract:

The integrated CO₂ capture and conversion through oxidative dehydrogenation of ethane (iCCC-ODHE) utilizes the captured CO₂ as a mild oxidant to promote value-added ethylene production. Nevertheless, it is still trapped by low efficiency owing to little understandings about the synergistic interaction between the CO₂ capture and catalytic ODHE. Herein, we focus on exploring the contributions of local catalytic environments to the iCCC-ODHE performance through tailoring the catalyst itself and the proximity-governed effect. The Co-ZSM-5 catalysts are developed to achieve a selective cleavage of the C-H bond over the C-C bond in C₂H₆ through modulating the relative concentration of Co²⁺. When coupling the optimized Co-ZSM-5 catalyst with the CO₂ adsorbent Ca₄MgO₅ by adjusting packing configurations in a fixed bed, a superior iCCC-ODHE performance with an excellent CO₂ capture capacity of 10.8 mmol g_adsorbent^‒1 and a remarkable C₂H₄ yield of 45.4% is achieved at 650 °C in the granule-stacking configuration. Consistently, the density functional theory calculations reveal the pathway of these abnormal phenomena that the low local CO₂ concentration around catalytic sites, corresponding to a relatively far proximity distance, shows a significant effect on decreasing the reaction energy of selective cleavage of the first C-H bond in C₂H₆. Meanwhile, the produced *H species can be consumed by the following adsorbed *CO₂, facilitating the shift of reaction equilibrium forwardly for the formation of C₂H₄ and CO. Therefore, this insight into the local catalytic environment provides a promising iCCC-ODHE strategy toward carbon neutrality.

Key words: CO₂ capture, Oxidative dehydrogenation of ethane, Co-ZSM-5/Ca₄MgO₅ dual functional materials, Local catalytic environment, C-H/C-C bonds selective cleavage