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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]

A series of highly ordered microporous Ce-based metal-organic frameworks (MOFs) were synthesized as the precursors for catalyst construction. The corresponding Ru catalysts were prepared by Ru impregnation on the derived CeO 2 by pyrolysis of Ce-MOF, and investigated for the CH 4 synthesis via CO 2 hydrogenation. Among the catalysts, Ru catalyst supported on the CeO 2 -B derived from Ce-BDC exhibited a highly competitive efficiency for CO 2 methanation, giving a CH 4 selectivity of 100% with a CO 2 conversion of 62% at 275 °C and 0.1 MPa, and the CH 4 productivity reached 0.49 mol/(mol Ru ·h). Characterization results revealed that more oxygen vacancies and corresponding surface oxygen species formed on the surface of CeO 2 -B derived from Ce-BDC caused to the stronger interaction between Ru and CeO 2 -B, which promoted the CO 2 adsorption and hydrogenation capacity of the catalyst, resulting in its better catalytic property. In situ diffuse reflectance infrared Fourier transform (DRIFT) studies further revealed that the route of HCOO* into CH 4 is a more competitive way of CO 2 hydrogenation to CH 4. [Display omitted] • CeO 2 supported Ru catalysts were constructed based on the heat-treatment strategy of Ce-MOFs. • Ru catalyst supported on CeO 2 -B exhibited a highly competitive efficacy for CO 2 methanation. • More oxygen vacancies and surface oxygen species were formed on CeO 2 -B surface. • The stronger interaction between Ru and CeO 2 -B promoted the CO 2 adsorption and hydrogenation. • The route of HCOO* into CH 4 is a more competitive way of CO 2 hydrogenation to CH 4. [ABSTRACT FROM AUTHOR]

• CuO-ZnO-ZrO 2 catalyst was prepared by a facile solvothermal route. • Effect of solvothermal temperature on performance of the catalyst was investigated. • The catalyst prepared at 180 °C exhibited the highest methanol yield. • The activity of the catalyst was closely related to capacity for H 2 adsorption. Solvothermal preparation of CuO-ZnO-ZrO 2 (CZZ) was realized using ethylene glycol as a solvent. The effects of solvothermal temperature (140–200 °C) on the properties of catalysts and catalytic performance in CO 2 hydrogenation were studied. ICP-OES, N 2 sorption, XRD, SEM-EDX, reactive N 2 O adsorption, XPS, H 2 -TPR, H 2 -TPD, and CO 2 -TPD were used as characterization tools. The data indicate that the CZZ-180 catalyst prepared at a solvothermal temperature of 180 °C has the smallest Cu crystallites and the largest surface area of Cu0, thus exhibiting the highest methanol yield. The effects of reaction temperature, pressure, and space velocity were also investigated. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Three CuO-ZnO-ZrO 2 -M x O y (CZZM, M = Cr, Mo and W) mixed oxides were prepared by a co-precipitation method and tested as catalysts for methanol synthesis from CO 2 hydrogenation. The catalysts were characterized by XRD, N 2 adsorption/desorption, XPS, reactive N 2 O adsorption, H 2 -TPR, and CO 2 -TPD techniques. The results indicated that the methanol selectivity and yield of the CuO-ZnO-ZrO 2 catalyst noticeably increased by the additions of MoO 3 and WO 3 , but slightly decreased by Cr 2 O 3 doping. Combining with the characterization results, the difference in methanol yield over the three catalysts can be attributed to the differences in their BET specific surface areas (S BET) and adsorption capacities for CO 2 , while the methanol selectivity is closely correlated to the ratio of surface contents of Zn to Cu, as well as the fraction of strong basic sites in the total basic sites of the investigated catalysts. Graphical abstract Image 1 Highlights • CuZnZrM (M = Cr/Mo/W) mixed oxides were used for methanol synthesis from CO 2 and H 2. • The CuO-ZnO-ZrO 2 -WO 3 catalyst shows the highest activity and methanol selectivity. • Methanol yield is related to the S BET and CO 2 adsorption capacity of the catalyst. • Methanol selectivity is closely related to the surface composition and basicity. [ABSTRACT FROM AUTHOR]

A series of CuO–ZnO–ZrO 2 catalysts are synthesized by a surfactant-assisted co-precipitation method and tested for the synthesis of methanol from CO 2 hydrogenation. The effects of calcination temperature on the physicochemical properties of as-prepared catalysts are investigated extensively by TG-DSC, N 2 adsorption/desorption, XRD, N 2 O chemisorption, SEM/TEM, EDX, XPS, TPR, H 2 -TPD and CO 2 -TPD techniques. The results show that the size of copper particles increases with the increase in calcination temperature, leading to the decrease in turnover frequency (TOF) for methanol formation. Moreover, compared with the counterparts prepared by the conventional co-precipitation method, the CuO–ZnO–ZrO 2 catalysts prepared by this novel method show significantly high methanol selectivity. The superior property of the prepared CuO–ZnO–ZrO 2 catalyst can be attributed to the formation of more amounts of Cu–ZnO x and/or Cu–ZrO x species resulted from the homogeneous element distribution, intimate interface contact of Cu species with ZnO and/or ZrO 2 , and to porous structure with larger pore size. [ABSTRACT FROM AUTHOR]

A series of CuO-ZnO-TiO2 catalysts with various TiO2 loadings were prepared by using a co-precipitation method. The prepared catalysts were characterized by using X-ray diffraction (XRD), N2 adsorption, reactive N2O adsorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), hydrogen temperature programmed desorption (H2-TPD), and CO2-TPD techniques, and tested the extent of methanol synthesis from carbon dioxide (CO2) hydrogenation. The results indicate that the addition of TiO2 to the CuO-ZnO catalyst makes the copper species exist in an amorphous-like structure or in much smaller crystallites, which promotes the reduction of CuO. Upon increasing the TiO2 loading, the metallic Cu surface area ( SCu) of the catalyst rises first and then decreases, exhibiting a maximum at a TiO2 loading of 10 %. The results of the catalytic experiments reveal that the addition of TiO2 favors the production of methanol, and an optimum catalytic activity is obtained at a TiO2 loading of 10 %. Moreover, the methanol yield increases linearly with the SCu of the catalysts, thereby indicating that the addition of TiO2 enhances the SCu but not the intrinsic activity. [ABSTRACT FROM AUTHOR]

Abstract: A series of Cu/ZrO2 catalysts with various La loadings for methanol synthesis from CO2 hydrogenation were prepared by a urea–nitrate combustion method. The catalysts were characterized with N2 adsorption, XRD, reactive N2O adsorption, XPS, TPR, H2-TPD and CO2-TPD techniques, and tested for methanol synthesis from CO2 hydrogenation. With increasing La loading, the Cu surface area increases first and then decreases, whereas the amount of basic site over catalysts increases continuously. The results of catalytic test reveal that a linear relationship exists between the conversion of CO2 and the Cu surface area. Moreover, it is found for the first time that the selectivity to methanol is related to the distribution of basic site on the catalyst surface. The presence of La favors the production of methanol, and the optimum catalytic activity is obtained when the amount of La doping is 5% of the total amount of Cu2+ and Zr4+. [Copyright &y& Elsevier]

Abstract: Cu/ZnO/ZrO2 catalysts were prepared by a route of solid-state reaction and tested for the synthesis of methanol from CO2 hydrogenation. The effects of calcination temperature on the physicochemical properties of as-prepared catalysts were investigated by N2 adsorption, XRD, TEM, N2O titration and H2-TPR techniques. The results show that the dispersion of copper species decreases with the increase in calcination temperature. Meanwhile, the phase transformation of zirconia from tetragonal to monoclinic was observed. The highest activity was achieved over the catalyst calcined at 400°C. This method is a promising alternative for the preparation of highly efficient Cu/ZnO/ZrO2 catalysts. [Copyright &y& Elsevier]

Abstract: A series of HZSM-5 zeolites modified with various contents of antimony oxide (0–30wt.%) were prepared by solid state ion reaction at 500°C, and the acidities of the resulted materials were characterized by temperature-programmed desorption of NH3. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the admixed catalysts of an industrial CuO–ZnO–Al2O3 methanol synthesis catalyst and the parent and antimony oxide modified HZSM-5 zeolites under pressurized fixed-bed continuous flow conditions. The results indicated that modification of HZSM-5 with suitable amount of antimony oxide significantly decreased the selectivity for undesired byproducts like hydrocarbons and carbon dioxide from 9.3% and 32.4% to less than 1% and 28%, respectively, so the selectivity for DME was enhanced greatly from 55% to 69% under temperature of 260°C, pressure of 4MPa and gas hourly space velocity of 1500mLh−1 . The decrease in the formation of hydrocarbons and carbon dioxide can be attributed to the significant decline in the amount of strong acid sites of the HZSM-5 zeolite induced by antimony oxide modification. Additionally, the influences of the operating parameters on the performance of the most efficient catalyst were also investigated. The results showed that high reaction temperature and high gas hourly space velocity resulted in both lower carbon monoxide conversion and lower dimethyl ether selectivity, so they should be no higher than 280°C and 3000mLh−1 , respectively. [Copyright &y& Elsevier]

Abstract: A series of CuO–ZnO–ZrO2 (CZZ) catalysts were synthesized by a glycine–nitrate combustion method and characterized by XRD, BET, N2O chemisorption, SEM and TPR techniques. The results show that the physicochemical properties of the catalysts are strongly influenced by the fuel content used in the combustion process. The dispersion of CuO exhibits an inverse-volcano variation trend with an increase in the glycine amount from 50% to 150% of the stoichiometry. The relationship between physiochemical properties and the fuel content is discussed in detail in terms of combustion temperature. The catalytic performance for the synthesis of methanol from CO2 hydrogenation was examined. The CZZ catalyst exhibits an optimum catalytic activity when 50% of stoichiometric amount of glycine was used. The turnover frequency has been calculated for various CZZ catalysts, and it reveals that the catalytic activities depend not only on the surface area of metallic copper but also on the phase state of ZrO2. [Copyright &y& Elsevier]

Abstract: Various CuO–ZnO–ZrO2 (CZZ) catalysts have been synthesized by urea–nitrate combustion method and their performances for methanol synthesis from CO2 hydrogenation have been investigated. The effects of urea/nitrate ratio on physicochemical and catalytic properties were studied by XRD, BET, H2-TPR and reactive N2O adsorption techniques. The results show that when 50% of stoichiometric amount of urea was used, the CZZ catalyst exhibited an optimum catalytic behavior. The combustion method was found to be a simple, fast and valuable route for the preparation of CZZ catalyst for methanol synthesis from CO2 hydrogenation. [Copyright &y& Elsevier]

Abstract: A series of CuO–TiO2–ZrO2 catalysts with various Ti and Zr molar ratios were prepared by co-precipitation method and characterized by N2 physisorption, X-ray diffraction (XRD) and temperature-programmed reduction of hydrogen (H2-TPR). The prepared CuO–TiO2–ZrO2 samples were mixed physically with HZSM-5 zeolite to synthesize dimethyl ether (DME) via CO2 hydrogenation. The results indicated that CuO–TiO2–ZrO2/HZSM-5 had higher CO2 conversion and DME yield compared to CuO–TiO2/HZSM-5 and CuO–ZrO2/HZSM-5 catalyst, in which the catalyst with equimole of Ti and Zr got the best performance. The activities of CuO–TiO2–ZrO2/HZSM-5 catalysts were well correlated to the reduction properties of CuO–TiO2–ZrO2 samples. [Copyright &y& Elsevier]

[Display omitted] • Fe and Na were found to be the most efficient promotors of Rh/CeO 2 catalyst for CO 2 hydrogenation to ethanol. • The optimized catalyst of 2Rh0.5Fe0.5Na/CeO 2 obtains a high ethanol selectivity of 29.8 % with a CO 2 conversion of 13.0 %. • The modification of Fe and Na promote the formation of Rh+ species, enhancing capacities of CO 2 adsorption and dissociation. • The Rh active sites synergized with Fe and Na can stabilize the adsorbed species of m-CO 3 2− and CO 3 H−. • The generation of HCOO*, CH 3 O* and CH 3 CH 2 O* intermediates promotes the ethanol formation. Rh catalyst is investigated as a strong candidate for CO 2 hydrogenation to ethanol, but it is still challenging because of the poor conversion efficiency. Here, by screening the promotors systematically and varying the amounts of components simultaneously, the optimized catalyst of 2Rh0.5Fe0.5Na/CeO 2 was found to highly efficient catalytic CO 2 hydrogenation to ethanol, giving a high ethanol selectivity of 29.8 % with a superior CO 2 conversion of 13.0 % at 250 °C, 3 MPa, and the ethanol productivity reached 116.7 mmol·g Rh −1·h−1. Characterization results revealed that the modification of Fe and Na, can promote the dispersion of Rh and the formation of Rh+ species, enhancing the capacities of CO 2 adsorption and dissociation. In situ DRIFT experiment illuminated that the Rh active sites synergized with Fe and Na can stabilize the adsorbed species of m-CO 3 2− and CO 3 H−, and promote the generation of HCOO* and CO* intermediates, which can be provided to couple with the CH x species, resulting in the high efficacy for ethanol synthesis from CO 2 hydrogenation. [ABSTRACT FROM AUTHOR]

A series of Cu@ZrO 2 -U framework catalysts derived from Cu@UiO-67 precursors with adjustable copper loadings were constructed by the deposition-precipitation method, and the catalytic activities of methanol synthesis via CO 2 hydrogenation were investigated. The optimized 20-Cu@ZrO 2 -U catalyst showed the best catalytic activity. At 3 MPa and 260 °C, the space-time yield of CH 3 OH (STY CH3OH) reached 2.28 mmol CH3OH /(g cat ·h), which was 3.5 times higher than that of 20-Cu/ZrO 2. The catalyst of 20-Cu@ZrO 2 -U also showed good stability during the 100-h time on stream test. The catalysts were further characterized by XRD, N 2 sorption, TEM, XPS, H 2 -TPR, CO 2 /H 2 -TPD and in situ DRIFTS. The characterization results showed that the stable ZrO 2 framework derived from UiO-67 is propitious to the confine of copper nanoparticles and formation of Cu+-ZrO 2 interfacial sites, which should be responsible for the excellent performance of methanol synthesis. Moreover, in situ DRIFTS was used to probe that the methanol synthesis via CO 2 hydrogenation over 20-Cu@ZrO 2 -U follows a HCOO∗-intermediated reaction pathway. [Display omitted] • A novel Cu@ZrO 2 -U framework catalyst was constructed by Cu@UiO-67 precursor strategy. • The optimized catalyst of 20-Cu@ZrO 2 -U was shown to form rich Cu+-ZrO 2 interfaces. • The methanol yield of 20-Cu@ZrO 2 -U was 3.5 times higher than 20-Cu/ZrO 2 catalyst. • The methanol productivity depends on the ratio of Cu+/Cu0 regulated by Cu+-ZrO 2 interface. • The methanol synthesis mechanism of Cu@ZrO 2 -U follows a HCOO∗-intermediate pathway. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu/ZnO x particles were encapsulated in UiO-66 by deposition–precipitation method. • Both of metal loading and Cu/Zn mole ratio can regulate the Cu-Zn interaction. • The amount of Cu/ZnO x interfaces is related to the methanol synthesis performance. A series of Cu-Zn catalysts encapsulated by Zr-based metal–organic frameworks (UiO-66) with various metal loadings and Cu/Zn mole ratios were prepared by the deposition–precipitation method, and the catalytic activities were investigated by CO 2 hydrogenation to methanol. The results showed that Cu-Zn@UiO-66 catalyst with Cu-Zn loading of 35 wt% and Cu/Zn mole ratio of 2.5 had the best catalytic activity. At 240 °C and 3 MPa, this catalyst gave the excellent catalytic activity with the highest methanol yield of 9.1%, and showed good reaction stability during 100-hour catalytic test. The catalysts were characterized by N 2 -sorption, XRD, TEM, XPS, H 2 -TPR and CO 2 -TPD. Such excellent performance benefits from the ultrasmall nanoparticles (NPs) and abundant Cu/ZnO x interfaces confined in the UiO-66, and the strong interaction between Cu and ZnO promotes the CO 2 conversion and methanol synthesis. [ABSTRACT FROM AUTHOR]

Various ionic liquids (ILs) were in situ prepared on coconut shell activated carbon (CSAC) granules. Cycloaddition of CO 2 to epichlorohydrin (ECH) was continuously carried out in a packed-bed reactor without using solvent or cocatalyst. The conversion rates of ECH over the CSAC tethered Bmim/Br, Bmim/BF 4 , Bmim-OH/Br and Bmim-COOH/Br were 63.4%, 74.5%, 83.4% and 85.9% at 140 °C and 1.4 MPa, respectively. The selectivities to epichlorohydrin carbonate (ECHC) were over 98% for the four catalysts. The ECH conversion stabilized at 82% for the CSAC tethered Bmim-COOH/Br after 50 h of continuous performance in the packed bed reactor. [ABSTRACT FROM AUTHOR]