Optimizing the Interfacial Environment of Triphasic ZnO-Cu-ZrO₂ Confined inside Mesoporous Silica Spheres for Enhancing CO₂ Hydrogenation to Methanol

Abstract

Achieving the desired catalytic activity and selectivity in CO2 hydrogenation to methanol remains a grand challenge using nonprecious metals. Herein, the well-known ternary Cu-ZnO-ZrO2 (CZZ) was spatially sequestered as fine, uniformly dispersed active interfaces onto an engineered mesoporous silica sphere (MSS), giving rise to Cu-ZnO-ZrO2/MSS (CZZ-MSS) with confined binary Cu-ZnO/Cu-ZrO2 and ternary interfaces that fostered methanol production under moderate conditions (30 bar and 200–280 °C). By systematically investigating the CZZ-MSS performance, we show that spatial confinement and optimization of the interfacial environment of the catalytically active interfaces inside well-fabricated mesoporous silica deliver a markedly enhanced specific methanol yield (2211 gMEOH·kgCu –1·h–1) compared to conventional supported catalysts including an industrial catalyst (368 gMEOH·kgCu –1·h–1) and a vast majority of reported catalysts. Besides, the strong metal–support interaction arising from interacting metallic Cu and metal oxides (ZnO and ZrO2) within the confined, ultrasmall nanoparticles (<3.0 nm) demotes the sintering of Cu NPs while retaining their H2 dissociation strength, resulting in superior and prolonged catalytic stability over 100 h. In situ DRIFTS of confined catalysts with monophasic, biphasic, and triphasic interfaces expectedly suggests the occurrence of different CO2 hydrogenation reaction paths over triphasic Cu-ZnO-ZrO2/MSS (formate pathway) compared to monophasic Cu/MSS (reverse water–gas shift (RWGS) pathway) and biphasic ZnO-ZrO2/MSS. From the appreciable insights gained herein, the rational support synthesis bringing the confinement effect to the robust ZnO-Cu-ZrO2 interface is the rationale behind the higher rate of methanol synthesis observed in the CO2 hydrogenation.

Constructing a core–shell Pt@MnOx/SiO2 catalyst for benzene catalytic combustion with excellent SO2 resistance: new insights into active sites

“…The binding energy of 103.3–103.5 eV is attributed to Si–OH, while the characteristic peak of Si–O–Si is in the range of 104.0–104.2 eV. 21…”

“…The binding energy of 103.3-103.5 eV is attributed to Si-OH, while the characteristic peak of Si-O-Si is in the range of 104.0-104.2 eV. 21 In the XPS spectra of Pt 4f (Fig. 8c-e), it can be seen that these samples contain two types of characteristic peaks.…”

“…19,20 For example, Chen et al confirmed that the structure of SiO 2 microspheres has a good pore confinement effect on the active interface, and the catalyst prepared based on this structure has excellent stability in the reaction. 21 In addition, SiO 2 carriers can effectively disperse nanoparticles of active species, which has great potential for application. 22,23 For instance, the Pt/SiO 2 catalysts synthesized by Jung et al exhibited excellent activity when used for CO oxidation, due to the good dispersion of Pt nanoparticles on SiO 2 and the effective removal of hydrocarbon impurities during the calcination process.…”

Intermetallic Palladium–Zinc Nanoparticles for the Ultraselective Hydrogenative Rearrangement of Furan Compounds

“…After adding H 2 , the electronic states of Pd and Zn remained unchanged, likely because of the limited hydrogen spillover of the PdZn alloy structure at 120 °C. Interestingly, when an H 2 –H 2 O mixed gas was introduced, the Pd peaks shifted to lower binding energies (Pd 3d 5/2 and Pd 3d 3/2 peaks at 335.7 and 340.9 eV, respectively) and the Zn peaks to higher binding energies (Zn 2+ 2p 3/2 and Zn 2+ 2p 1/2 peaks at 1021.8 and 1044.7 eV, respectively) . Moreover, Zn LMM XAES spectra showed a shift in the metallic Zn LMM Auger peak to a lower kinetic energy (991.0 eV), which demonstrated the partial oxidation of the metallic Zn species (Figure C). , Notably, the in situ O 1s XPS results could not be reliably evaluated because of the abundant lattice oxygen in the ZnO supports.…”

Push–Pull Engine─Electron Pumping by Anchored Ligands over ZnO/C: Boosting Photo-Fenton-Like Catalysis without Additional Oxidants

“…Hydrogen peroxide (H 2 O 2 ) is an environment friendly oxidant that exhibits strong oxidizing properties with benign byproducts. , Thus, it is useful in various chemical processes including the Fenton process. , However, storage, transportation, and handling of concentrated H 2 O 2 is risky . In addition, these processes require regular replenishment of H 2 O 2 , as the high concentration leads to the rapid activation of H 2 O 2 to the short-lived ROS .…”