Gas-Dependent Active Sites on Cu/ZnO Clusters for CH₃OH Synthesis

Abstract

This study describes an instantaneously gas-induced dynamic transition of an industrial Cu/ZnO/Al 2 O 3 catalyst. Cu/ ZnO clusters become "alive" and lead to a promotion in reaction rate by almost one magnitude, in response to the variation of the reactant components. The promotional changes are functions of either CO 2 -to-CO or H 2 O-to-H 2 ratio which determines the oxygen chemical potential thus drives Cu/ZnO clusters to undergo reconstruction and allows the maximum formation of Cu−Zn 2+ sites for CH 3 OH synthesis.

Enhanced Methanol Synthesis over Self‐Limited ZnOx Overlayers on Cu Nanoparticles Formed via Gas‐Phase Migration Route

“…For the Cu/Al 2 O 3 ‐CO 2 /H 2ZnO ‐100 catalyst, only the Auger peak of Zn 2+ at 498.2 eV exists, while an obvious shoulder feature of Zn 0 at 493.6 eV appears in addition to the Auger peak of Zn 2+ in the Cu/Al 2 O 3 ‐H 2ZnO ‐100 catalyst. Besides, Cu 2p and Cu LMM Auger spectra acquired from quasi in situ X‐ray photoelectron spectroscopy (XPS) experiments of the two catalysts show the identical Cu 2p 3/2 core level peak (932.0 eV) and Cu LMM Auger peak (567.4 eV) of Cu 0 (Figure S1), confirming that Cu NP S exist in the form of a metallic state in these catalysts after the treatment [9] . High‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) and corresponding energy dispersive spectroscopy (EDS) elemental analysis have been utilized to observe distribution of Zn species in the catalysts.…”

“…Besides, Cu 2p and Cu LMM Auger spectra acquired from quasi in situ X-ray photoelectron spectroscopy (XPS) experiments of the two catalysts show the identical Cu 2p 3/2 core level peak (932.0 eV) and Cu LMM Auger peak (567.4 eV) of Cu 0 (Figure S1), confirming that Cu NP S exist in the form of a metallic state in these catalysts after the treatment. [9] Highangle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and corresponding energy dispersive spectroscopy (EDS) elemental analysis have been utilized to observe distribution of Zn species in the catalysts. The Cu/Al 2 O 3 catalyst (Figure S2) shows clean Cu particle surface.…”

Understanding the Synergistic Catalysis in Hydrogenation of Carbonyl Groups on Cu-Based Catalysts

“…Cu-based catalysts show broad applicability in the chemical industry for the hydrogenation of carbon–oxygen bonds in aldehydes, , CO/CO 2 , , acids, and esters, due to its moderate ability toward hydrogen activation and inactive toward the C–C cleavage. , To reveal the active sites of Cu-based catalysts is a hot research topic in scientific and practical research. − The strong metal and support interaction stabilizes Cu species and introduces interfacial sites, including Cu 0 –Cu + and O V -included Cu–O x –support (0 < x < 2, O V represents oxygen vacancies on reducible oxides). − The synergy between Cu 0 and Cu + has been proved to enhance reaction rates, with Cu 0 facilitating H 2 dissociation and Cu + targeting carbonyl groups. − Despite being cited and discussed by numerous researchers, this conclusion lacks kinetic evidence to verify the respective roles of Cu + and Cu 0 . Moreover, the reason why a balanced Cu + /Cu 0 ratio improves the activity of Cu-based catalysts remains a topic of debate. , Moreover, the influence of the Cu valence state on product distributions is vital but has received limited attention to date. , Another scientific issue is discussed about the interface between Cu and support, which has been verified to heterolytically dissociate H 2 and stabilize transition states, thereby promoting the hydrogenation of dimethyl oxalate (DMO) on Cu/SiO 2 .…”

Tuning interfaces between Cu and oxide via atomic layer deposition method for CO2 hydrogenation to methanol

“…2,9–11 Many studies have shown that copper catalyst with a ZnO-based support is active for the methanol synthesis process in CO 2 hydrogenation. 10,12–15 For instance, Kattel et al reported that the ZnO–Cu interface was the active site for methanol synthesis from CO 2 hydrogenation via a formate intermediate. 12 Behrens et al highlighted that the presence of Cu steps decorated with Zn atoms resulted from the strong metal–support interaction in the industrial Cu/ZnO/Al 2 O 3 catalyst significantly boosted the adsorption of the intermediates and thus promoted methanol formation.…”