Enhanced CH₄ Production from CO₂ Hydrogenation on γ-AlOOH-Supported Cobalt Catalyst with Abundant Surface Coordination Unsaturated Oxygen Atoms

Under the context of growing greenhouse effect, it is of great interest to hydrogenate CO2 into high-valuable hydrogen-containing chemicals (e.g., CH4) which can be further used as fuels, hydrogen carriers, and raw materials for industry. Herein, we first fabricate a catalyst support denoted by Al-D0, which is composed of boehmite (γ-AlOOH), and then increase the content of surface coordination unsaturated O (Ouns) atoms on Al-D0 to form another catalyst support denoted by Al-D60. During CO2 hydrogenation by H2, the Al-D0-supported Co catalyst (Co/Al-D0) and the Al-D60-supported Co catalyst (Co/Al-D60) show different performance. CO2 conversion in CO2 hydrogenation on Co/Al-D60 (22.10%) is higher by 10.94 times than that on Co/Al-D0 (2.02%). Only CO is produced from CO2 hydrogenation on Co/Al-D0, but Co/Al-D60 enhances the CH4 production from CO2 hydrogenation. The more abundant Ouns on Co/Al-D60 facilitates CO2 adsorption and activation on Co/Al-D60. This leads more activated CO2 to participate in the hydrogenation reaction, thus increasing CO2 conversion on Co/Al-D60. The more activated CO2 could easily capture H from H2 dissociation, thus enhancing CH4 production on Co/Al-D60. The present work provides a new strategy for developing a more efficient catalyst for CO2 hydrogenation to high-value hydrogen-containing chemicals.