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A series of ZnO/ZrO2 catalysts were synthesized by the precipitation method. The effect of different precipitation modes on the physicochemical properties of the ZnO/ZrO2 catalysts for CO2 hydrogenation to methanol was investigated. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, transmission electron microscopy (TEM), temperature programmed desorption of CO2 (CO2-TPD), temperature programmed reduction of H2 (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The results showed that the catalyst of ZnO/ZrO2 prepared by the concurrent precipitation method had more CO2 adsorption sites, resulting in its higher CO2 conversion. While the stepwise precipitation mode increased the surface oxygen content of ZnO/ZrO2, which enhanced the methanol selectivity. Overall, the ZnO/ZrO2 prepared by the concurrent precipitation mode exhibited a highly competitive efficacy for CO2 hydrogenation, giving a methanol selectivity of 81.4% with a CO2 conversion of 5.1% at 280 ℃ and 3 MPa, and the methanol yield reached 4.2%. The effect of different precipitation modes on the physicochemical properties of the ZnO/ZrO2 catalysts for CO2 hydrogenation to methanol was investigated, and the ZnO/ZrO2 prepared by the concurrent precipitation mode exhibited a highly competitive efficacy for CO2 hydrogenation. [ABSTRACT FROM AUTHOR]

A series of Cu-ZnO-ZrO2 (CCZ) catalysts were prepared by the solvothermal method with different solvothermal times (1 h, 3 h, 6 h, and 12 h). The physicochemical properties of these catalysts and the catalytic performance for CO2 hydrogenation to methanol were studied. The highest methanol yield was achieved when the solvothermal time was 6 h (CCZ-6). Furthermore, we found that the copper surface area (SCu) increases and then decreases with an increase in the solvothermal time and that there is a strong correlation between the methanol yield and the SCu. This research highlights the crucial influence of the solvothermal time on the structure and catalytic behavior of Cu-ZnO-ZrO2 catalysts, providing a valuable reference for the development of efficient catalysts. [ABSTRACT FROM AUTHOR]

Maintaining high conversion under the premise of high oxygenates selectivity in syngas conversion is important but a formidable challenge in Rh catalysis. Monometallic Rh catalysts provide poor oxygenate conversion efficiency, and efforts have been focused on constructing adjacent polymetallic sites; however, the one‐pass yields of C2+ oxygenates over the reported Rh‐based catalysts were mostly <20 %. In this study, we constructed a monometallic Rh catalyst encapsulated in UiO‐67 (Rh/UiO‐67) with enhanced proximity to dual‐site Rh1,2‐Rhn ensembles. Unexpectedly, this catalyst exhibited high efficacy for oxygenate synthesis from syngas, giving a high oxygenate selectivity of 72.0 % with a remarkable CO conversion of 50.4 %, and the one‐pass yield of C2+ oxygenates exceeded 25 %. The state‐of‐the‐art characterizations further revealed the spontaneous formation of an ensemble of Rh single atoms/dimers (Rh1,2) in the proximity of ultrasmall Rh clusters (Rhn) confined within the nanocavity of UiO‐67, providing adjacent Rh+‐Rh0 dual sites dynamically during the reaction that promote the relay of the undissociated CHO species to the CHx species. Thus, our results open a new route for designing highly efficient Rh catalysts for the conversion of syngas to oxygenates by precisely tuning the ensemble and proximity of the dual active sites in a confined space. [ABSTRACT FROM AUTHOR]

A series of CuO-ZnO–ZrO2 (CZZ) catalysts were synthesized via a solvothermal method. The effects of four saturated monohydric alcohols (methanol, ethanol, n-propanol, and n-butanol) as solvents on the physicochemical properties and catalytic performance for the direct synthesis of methanol from CO2 hydrogenation of the prepared catalysts were investigated. N2 physical adsorption, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectroscopy mapping, reactive N2O adsorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction by H2 (H2-TPR), and temperature programmed desorption (H2-TPD, CO2-TPD) techniques were used to characterize the catalysts. The results indicate that the catalyst prepared with methanol as solvent (CZZ-M) has the smallest Cu crystallites and the largest metallic Cu surface area, thus exhibiting the highest methanol yield of 7.4% at 240 °C, 3.0 MPa, H2:CO2 of 3 (v/v), and GHSV of 2400 mL/(gcat·h). [ABSTRACT FROM AUTHOR]

H3PW12O40-modified MnOx catalysts (denoted as Mn-HPW) were used for NOx elimination with co-fed NH3. The optimal Mn-HPW0.02 catalyst exhibited over 90% NOx conversion at 90–270 °C. The incorporation of HPW increased the amount of Lewis acid sites of the catalyst for adsorbing NH3, and accelerated the reaction between the adsorbed NH3 species and gas-phase NOx, thus, increasing the low-temperature catalytic activity. The oxidation ability of the Mn catalyst was decreased due to the addition of HPW, thus, mitigating the overoxidation of the adsorbed NH3 species and improving the de-NOx activity and N2 selectivity in the high-temperature region. DRIFT results revealed that the NH3 species on Lewis and Brønsted acid sites, bridged nitrate, and bidentate nitrate were important species/intermediates for the reaction. NH3-SCR over the Mn and Mn-HPW0.02 catalysts obeyed the Eley–Rideal and Langmuir–Hinshelwood mechanisms, simultaneously, at 120 °C. [ABSTRACT FROM AUTHOR]

A series of Mn3Co16Ox composite oxides catalysts were fabricated via a solid-phase synthesis using different manganese precursors (namely manganese acetate (A), nitrate (N), and sulfate (S)). It has been demonstrated that the obtained catalysts presented variable catalytic activities for CO oxidation and remarkable diversity of physicochemical properties closely depending on the manganese precursors. In detail, the catalytic activity and catalytic durability for CO oxidation under humid conditions generally followed a descending order of Mn3Co16Ox-A > Mn3Co16Ox-N > Mn3Co16Ox-S. The optimum catalytic performance of Mn3Co16Ox-A was predominantly attributed to its larger specific surface area, significantly higher low-temperature reducibility and lattice oxygen mobility, and more plentiful oxygen vacancies. [ABSTRACT FROM AUTHOR]

Ni-modified Ag/SiO2 catalysts containing 0~3 wt.% Ni were obtained by impregnating Ni species onto Ag/SiO2 followed by calcination and reduction. The catalysts' performance in the hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) was tested. Ag-0.5%Ni/SiO2 showed the highest catalytic activity among these catalysts and exhibited excellent catalytic stability. The effects of the Ni content on the structure and surface chemical states of catalysts were investigated by XRF, N2-sorption, XRD, TEM, EDX-mapping, FT-IR, H2-TPR, UV–vis, and XPS. The better catalytic activity and stability of Ni-modified Ag/SiO2 (versus Ag/SiO2) are ascribed to the improved dispersion of active Ag species as well as the higher resistance to the growth of Ag particles due to the presence of Ni species. [ABSTRACT FROM AUTHOR]