Perspective on the one-step CO2 hydrogenation to dimethyl ether

The hydrogenation of CO2 to dimethyl ether (DME) is a potential method for the efficient utilization of CO2 as a renewable resource. In comparison with the photocatalytic and electrocatalytic routes, the thermal conversion of CO2 over a solid catalyst exhibits a higher efficiency. However, the reported catalysts for the one-step hydrogenation of CO2 to DME commonly suffer from a lower activity and a poorer stability. In this perspective, progresses on the structure of active sites and the reaction mechanism of the one-step hydrogenation of CO2 to DME are summarized for the Cu-based bifunctional catalyst and the recently reported GaN catalyst. In the case of the Cu-based bifunctional catalyst, DME is formed via the CO2 hydrogenation to methanol and the dehydration of the intermediate methanol to DME. Moreover, copper at reduced state (Cu0, Cu+ or Cuδ+, 0<δ<2) is the active site for the CO2 hydrogenation, and the DME yield and the stability of the bifunctional catalyst are mainly determined by the dispersion and the stability of reduced Cu, the strength and distribution of acid sites, and the synergetic effect between reduced Cu and the acid sites. In contrast, the GaN catalyzed DME synthesis proceeds via the direct hydrogenation of CO2 to the primary product of DME, which is totally different from that over the Cu-based bifunctional catalysts. Based on these analyses, the challenges and the further researches on the one-step hydrogenation of CO2 to DME are provided, and the benefit of the DME economy is remarked. © 2022, Chemical Industry Press Co., Ltd. All right reserved.