Role of cobalt aluminate in CO ₂ hydrogenation over cobalt‐based catalyst

Carbon dioxide (CO 2 ) hydrogenation has attracted great attentions. Cobalt (Co) based catalysts, for example, hydroxyaluminum oxide (AlOOH) supported Co catalyst (Co/AlOOH), have been widely explored for CO 2 hydrogenation. Cobalt aluminate (CoAl 2 O 4 ) usually appears on Co‐based catalysts, but its role in CO 2 hydrogenation is still an open question. Herein, we tune the ratio of metallic Co 0 to CoAl 2 O 4 on Co/AlOOH, fabricating a CoAl‐p‐R120 catalyst. During CO 2 hydrogenation at 375°C, CoAl‐p‐R120 increases CO 2 conversion to 23.93%, and enhances methane (CH 4 ) production. CoAl 2 O 4 on CoAl‐p‐R120 provides active sites for CO 2 adsorption and conversion to form carboxyl (COOH*) which is a key intermediate in CO 2 hydrogenation, thus boosting CO 2 hydrogenation via a pathway: CO 2 → COOH* → carbon monoxide → CH 4 . However, more CoAl 2 O 4 on catalyst than that on CoAl‐p‐R120 limits CO 2 hydrogenation. These results are helpful for fabricating more efficient transition metal catalysts for CO 2 hydrogenation.