Cu-based catalysts have been widely studied for direct hydrogenation of CO 2 to methanol. Their activities quite depend on the amount of exposed active sites (e.g., Cu-oxide interfaces), which can be tuned by the particle size as well as porosity. Here, we report an active, selective, and stable Cu@ZrO x catalyst with a three-dimensional (3D) porous framework structure via the in situ reconstruction of size-confined Cu@UiO-66. The optimized CU-0.5-300 catalyst shows a high methanol selectivity of 78.8% at a conversion of 13.1% at 260 °C, 4.5 MPa, giving a methanol space-time yield of 796 g•kg cat −1•h −1 . It also shows long-term stability for 105 h in a time-onstream test. Such good performance benefits from abundant Cu−ZrO x interfaces and a stable 3D ZrO x framework. During the reaction, ZrO x species in situ evolves from the unstable Zr-oxide cluster (the building unit of UiO-66) or amorphous ZrO 2 to a stable tetragonal ZrO 2 phase, but strong metal−support interaction (SMSI) at Cu−ZrO x interfaces retains. The SMSI enables the formation of Cu + at the ZrO 2 surface, which is strongly associated with the active sites for methanol synthesis. In situ diffuse-reflectance infrared Fourier transform spectroscopy studies reveal methanol synthesis which follows a HCOO-intermediated pathway. It is believed that this work provides an "in situ reconstruction" strategy to fabricate a practical Cu@ZrO x framework catalyst for methanol production.

Cu–ZnO catalysts are widely studied for the direct hydrogenation of CO2 to methanol for high activity. However, despite the widespread research, promoting the intrinsic activity of active sites remains a contentious topic. We here report a facile strategy to manufacture ZnFe2O4 spinel-supported Cu catalysts with a tuneable size of Cu nanoparticles for selective methanol synthesis from CO2 hydrogenation. The optimized 33Cu/ZnFe-0.5 catalyst exhibits a high methanol selectivity of 71.6% at a CO2 conversion of 9.4% at 260 °C and 4.5 MPa. Increasing the Zn/Fe ratio decreases the selectivity of methanol at the same CO2 conversion and especially at lower CO2 conversions. The generation of extra Cu+ sites at Cu–spinel interfaces instead of Cu–ZnO x interfaces markedly inhibits the reverse water gas shift reaction during CO2 hydrogenation. The roles of Cu sites in methanol synthesis from CO2/H2 are that the Cu–ZnO interfaces act as the active sites for speeding up the production of methanol, while the Cu+ sites at the Cu–spinel interfaces act as synergy sites for improving the methanol selectivity and activity of each Cu–ZnO site.

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Alkali metal promoters are widely used to modify active metal sites/ interfaces of heterogeneous catalysts for numerous industrial processes. However, the interplay between an alkali metal and support, a crucial catalytic parameter, has been scarcely investigated in controlling the activation behaviors of intermediates and improving catalysis. Herein, we report that K−ZrO 2 interfaces can boost the production of higher alcohols (HA) from CO 2 hydrogenation over an amorphous ZrO 2 -supported K−Cu−Fe catalyst (KFeCu/a-ZrO 2 ). In situ spectroscopy and chemisorption demonstrate that the strong interactions between K and ZrO 2 induce the formation of surface Zr δ+ sites/oxygen vacancies at K−ZrO 2 interfaces, thus providing plenty of nondissociative CO activation sites. The improved molecular CO adsorption capacity at the K−ZrO 2 interfaces expedites the CO insertion reaction (*CH x + *CO → *CH x -CO) at Cu−Fe 5 C 2 interfaces, thereby driving the HA synthesis reaction with nearly 4.6 times higher activity of HA in comparison to the KFeCu/SiO 2 catalyst. At the optimal conditions of 320 °C, 4 MPa, and 12 L g cat −1 h −1 , the KFeCu/a-ZrO 2 catalyst shows the HA space time yield of 125.0 mg g cat −1 h −1 , ranking the top level among the reported single-component catalysts in the literature. Most importantly, this work provides an in-depth insight into alkali promoter−support interactions for promoting catalytic performance.