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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 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]

• 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: A series of CuO-ZnO-ZrO2 catalysts were synthesized by the polymeric precursor method, and characterized by X-ray diffraction (XRD), N2 physisorption, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed reduction with H2 (H2-TPR), reactive N2O adsorption, and adsorption of H2 and CO2 followed by temperature-programmed desorption (H2-TPD, CO2-TPD) techniques. The catalytic performances of all samples for methanol synthesis from hydrogenation of CO2 were evaluated under the experimental condition of 240 °C, 3 MPa, and SV = 1800-6000 mL·gcat−1·h−1. The effects of the calcination temperature on physicochemical and catalytic properties of all catalysts were investigated. The results indicate that the catalyst prepared under 400 °C calcination possesses the smallest Cu crystallites, largest metallic Cu surface area, and thus exhibits the highest methanol yield.With the calcination temperature increasing, the methanol selectivity increased continuously, while the CO2 conversion increased first and then decreased, with a maximum at 400 °C. CuO-ZnO-ZrO2 catalysts were prepared by polymeric precursor method under different temperatures.The catalyst prepared under 400 °C possessed the highest dispersion of Cu.The catalyst prepared under 400 °C exhibited the highest yield of methanol.The methanol yield was closely related to the metallic Cu surface area (SCu) of catalysts. [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 WO 3 modified CuO-ZnO-ZrO 2 mixed oxides with different WO 3 contents (0–20 at.%) were prepared by co-precipitation method and used as catalyst for methanol synthesis from CO 2 hydrogenation. The effects of WO 3 content on the physicochemical and catalytic properties of the CuO-ZnO-ZrO 2 -WO 3 catalysts were investigated by X-ray diffraction, X-ray photoelectron spectra, temperature-programed reduction of hydrogen, temperature-programed desorption of CO 2 , N 2 adsorption and desorption, reactive N 2 O adsorption, and activity testing. The results indicated that both CO 2 conversion and methanol selectivity of the CuO-ZnO-ZrO 2 catalyst was enhanced by the addition of small amounts (2 and 5 at.%) of WO 3 . However, the activity was significantly decreased by the addition of excessive WO 3 (20 at.%). The activity was closely related to the specific surface area of metallic Cu ( S Cu ), amount of weak basic sites, and reducibility of the catalyst. [ABSTRACT FROM AUTHOR]

Three CuO-ZnO-TiO2-ZrO2 catalysts with the same composition were prepared through sol-gel, solid-state reaction, and solution-combustion methods and characterized by X-ray diffraction (XRD), N2 adsorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction with H2 (H2-TPR), reactive N2O adsorption, and adsorption of H2 and CO2 followed by temperature-programmed desorption (H2-TPD, CO2-TPD) techniques. Their catalytic performances for CO2 hydrogenation to methanol were tested in a fixed-bed reactor under the conditions of 200-280 °C, 3 MPa, and SV = 2400 mL gcat−1 h−1. The results indicated that the texture, structure, reducibility, and adsorption capacity for reactants of the CuO-ZnO-TiO2-ZrO2 catalyst were affected noticeably by preparation methods and the catalyst prepared by sol-gel method exhibited the highest CO2 conversion and methanol selectivity, which reached to 17.0% and 44.0%, respectively. The highest activity of the CuO-ZnO-TiO2-ZrO2 catalyst prepared by sol-gel method was attributed to the largest metallic Cu surface area and adsorption capacity for H2.The catalyst prepared by sol-gel method exhibits the highest performance for methanol synthesis, which was attributed to the largest metallic Cu surface area and adsorption capacity for H2. CuO-ZnO-TiO2-ZrO2 catalyst was prepared by three different methods.The catalyst prepared by sol-gel method exhibited the highest yield of methanol.The catalyst prepared by solution combustion exhibited the lowest methanol yield.The superior activity of the sol-gel method derived catalyst was attributed to the largest SCu. [ABSTRACT FROM AUTHOR]

The influence of TiO 2 , ZrO 2 , and TiO 2 –ZrO 2 mixed oxide on the catalytic performance of CuO–ZnO catalyst in the methanol synthesis from CO 2 hydrogenation was studied. The catalysts were prepared by oxalate co-precipitation method and characterized by TGA, N 2 adsorption, XRD, reactive N 2 O adsorption, XPS, H 2 -TPR, H 2 -TPD, and CO 2 -TPD techniques. Characterization results reveal that all the additives improve the CuO dispersion in the catalyst body and increase the Cu surface area and adsorption capacities of CO 2 and H 2 . The results of catalytic test reveal that the additives increase both the CO 2 conversion and methanol selectivity, and TiO 2 –ZrO 2 mixed oxide is more effective than single components of TiO 2 or ZrO 2 . Moreover, the activity of methanol synthesis is correlated directly with CO 2 adsorption capacity over the catalysts. [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]

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]