关键词: 二氧化碳加氢, 二甲醚, 氮化镓, 铜, 双功能催化剂

Abstract:

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 Cu ^δ+, 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.

Key words: CO₂ hydrogenation, dimethyl ether, gallium nitride, copper, bifunctional catalyst