Performance Exploration of Ni-Doped MoS[sub.2] in CO[sub.2] Hydrogenation to Methanol

The preparation of methanol chemicals through CO[sub.2] and H[sub.2] gas is a positive measure to achieve carbon neutrality. However, developing catalysts with high selectivity remains a challenge due to the irreversible side reaction of reverse water gas shift (RWGS), and the low-temperature characteristics of CO[sub.2] hydrogenation to methanol. In-plane sulfur vacancies of MoS[sub.2] can be the catalytic active sites for CH[sub.3]OH formation, but the edge vacancies are more inclined to the occurrence of methane. Therefore, MoS[sub.2] and a series of MoS[sub.2]/Ni[sub.x] and MoS[sub.2]/Co[sub.x] catalysts doped with different amounts are prepared by a hydrothermal method. A variety of microscopic characterizations indicate that Ni and Co doping can form NiS[sub.2] and CoS[sub.2], the existence of these substances can prevent CO[sub.2] and H[sub.2] from contacting the edge S vacancies of MoS[sub.2], and the selectivity of the main product is improved. DFT calculation illustrates that the larger range of orbital hybridization between Ni and MoS[sub.2] leads to CO[sub.2] activation and the active hydrogen is more prone to surface migration. Under optimized preparation conditions, MoS[sub.2]/Ni[sub.0.2] exhibits relatively good methanol selectivity. Therefore, this strategy of improving methanol selectivity through metal doping has reference significance for the subsequent research and development of such catalysts.