Breaking the activity–selectivity trade-off of CO <sub>2</sub> hydrogenation to light olefins
Xiaoyue Wang, Ting Zeng, Xiaohong Guo, Zhiqiang Yan, Hongyan Ban, Ruwei Yao, Congming Li, Xiang‐Kui Gu, Mingyue Ding
Abstract
Catalytic hydrogenation of CO 2 to value-added fuels and chemicals is of great importance to carbon neutrality but suffers from an activity–selectivity trade-off, leading to limited catalytic performance. Herein, the ZnFeAlO 4 + SAPO-34 composite catalyst was designed, which can simultaneously achieve a CO 2 conversion of 42%, a CO selectivity of 50%, and a C 2 –C 4 = selectivity of 83%, resulting in a C 2 –C 4 = yield of almost 18%. This superior catalytic performance was found to be from the presence of unconventional electron-deficient tetrahedral Fe sites and electron-enriched octahedral Zn sites in the ZnFeAlO 4 spinel, which were active for the CO 2 deoxygenation to CO via the reverse water gas shift reaction, and CO hydrogenation to CH 3 OH, respectively, leading to a route for CO 2 hydrogenation to C 2 –C 4 = , where the kinetics of CO 2 activation can be improved, the mass transfer of CO hydrogenation can be minimized, and the C 2 –C 4 = selectivity can be enhanced via modifying the acid density of SAPO-34. Moreover, the spinel structure of ZnFeAlO 4 possessed a strong ability to stabilize the active Fe and Zn sites even at elevated temperatures, resulting in long-term stability of over 450 h for this process, exhibiting great potential for large-scale applications.