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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]

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 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]

Abstract: The effect of titanium promotion on the catalytic performance of Rh-Mn-Li catalyst supported on PVP-modified SiO2 for C2+ oxygenates synthesis from CO hydrogenation was investigated. The highest selectivity toward C2+ oxygenates (51.3%) was achieved over the RML/0.5Ti/SiO2 catalyst. Characterization results indicates that the addition of Ti promotes the adsorption of geminal CO and the formation of Rh+, which is favorable for the CO insertion into metal-CHx band, and finally increases the selectivity of C2+ oxygenates.Graphical Abstract: The effect of titanium promotion on the catalytic performance of Rh-Mn-Li catalyst supported on PVP-modified SiO2 for C2+ oxygenates synthesis from CO hydrogenation was investigated. The highest selectivity toward C2+ oxygenates (51.3%) was achieved over the RML/0.5Ti/SiO2 catalyst [ABSTRACT FROM AUTHOR]

A series of CuO-ZnO-Al 2 O 3 -Li 2 O catalysts with various Al 2 O 3 /Li 2 O mass ratios were prepared by co-precipitation method and characterized by several techniques such as XRD, N 2 adsorption, SEM/EDX, reactive N 2 O adsorption, XPS/XAES, H 2 -TPR, H 2 -TPD, and CO-TPD. The results revealed that the specific surface area ( S BET ), dispersity of Cu species, metallic Cu surface area ( S Cu ) and adsorption capacity for reactants (H 2 and CO) were increased by the addition of suitable amount of Li 2 O to the CuO-ZnO-Al 2 O 3 catalyst, thus enhancing the catalytic activity of the hybrid catalyst composed of CuO-ZnO-Al 2 O 3 and HZSM-5 for the direct synthesis of dimethyl ether from biomass-derived gas. Furthermore, the addition of Li 2 O significantly improved the stability of CuO-ZnO-Al 2 O 3 catalyst due to the effective inhibition of the crystallization of Cu and ZnO. [ABSTRACT FROM AUTHOR]

A series of CuO-ZnO-ZrO2 catalysts was prepared by a facile microwave-assisted hydrothermal synthesis method and used for the direct synthesis of methanol by CO2 hydrogenation in a fixed-bed reactor at 240 °C, 3.0 MPa, CO2/H2=1:3 ( v/ v), and space velocity of 2400 mL gcat−1 h−1. The effects of the hydrothermal synthesis temperature (80-150 °C) on the physicochemical properties and catalytic activity of the CuO-ZnO-ZrO2 catalysts were investigated by using several techniques, including XRD, N2 adsorption, reactive N2O adsorption, SEM with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction by H2, and the temperature-programmed desorption of adsorbed CO2 and H2. The catalyst prepared at 120 °C possessed a high surface area, a high dispersion of Cu species, a high adsorption capacity for CO2 and H2, and thus exhibited a high CO2 conversion and methanol selectivity. The surface area of metallic Cu ( SCu) is the critical factor in determining the activity of the CuO-ZnO-ZrO2 catalyst. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of amino acid methyl esters to chiral amino alcohols is an important and fascinating process. The CuZnMgAlO catalyst for the synthesis of chiral amino alcohols was prepared by the fractional co-precipitation method in the 50-100 g scale. The effect of the reduction gas on the catalytic activity, and the effects of the reaction conditions (R-p-m/Cat, temperature, reaction time, H pressure and solvent) on the catalytic hydrogenation of R-phenylglycine methyl ester (marked as R-p-m) were investigated. When R-p-m in the ethanol solvent was hydrogenated at 5 MPa of H and 80 °C for 10 h over this catalyst reduced by H, 87.7% yield of R-phenylglycinol with ~ 100% ee value was obtained, and its reaction activation energy (E) was 36.7 kJ/mol. After repeated usage 16 times, its catalytic activity was hardly varied. Using this catalyst to catalyze the preparation of other amino alcohols, the high yield of product with ~100% ee value was obtained also. Graphical Abstract: [ABSTRACT FROM AUTHOR]

It has been reported widely that Rh-Mn-Li/SiO 2 catalysts can exhibit high selectivity to C 2 + oxygenates during CO hydrogenation, with promoters of Mn and Li playing an important role in this behavior. In this study, a series catalysts of Rh-Mn-Li/SiO 2 with different amounts of Mn and Li were prepared, and the new insights into the effects of Mn and Li on the mechanistic pathway for C 2 + oxygenates synthesis from syngas were investigated. The XPS analysis showed that Rh existed mainly as metallic Rh after reduction, however partially positively charged Rh δ+ atoms appeared on the surface of Mn-containing catalyst due to the interaction of Rh-Mn. The results of H 2 -TPR indicated that both of Li and Mn can inhibit the reduction of Rh 2 O 3 . With the increase in the ratio of Mn/Rh, the most effective interaction, associated to the presence of two reduction centers of Rh 2 O 3 , was obtained when the ratio of Mn/Rh = 1. In situ -FTIR was used to probe the effects of Mn and Li on CO absorption and hydrogenation. With regards to the CO adsorption, the doping of Mn can enhance the CO adsorption ability of Rh and weaken the CO-Rh bond strength very effectively when the amount of Mn reached 1.5 wt.%. Improved capacity of CO adsorption is conducive to increase of CO conversion, while the weakening of CO-Rh bond is beneficial to the CO insertion reaction, thus contributing to the generation of C 2 + oxygenates. Moreover, the low amount of Li (≤0.075 wt.%) can also enhance the CO adsorption, resulting in the improvement of reactivity. On the other hand, Mn and Li promoted dissociation of H 2 , which is favorable to an increase in the rate of hydrogenation. But an opposite effect appeared at high content of Mn (>1.5 wt.%). As the optimized results, when Rh, Mn, Li content was 1.5 wt.%, 1.5 wt.% and 0.075 wt.%, the catalyst for CO hydrogenation of C 2 + oxygenates achieved the best performance of C 2 + oxygenates synthesis. [ABSTRACT FROM AUTHOR]

The effects of different impregnation sequences of copper and iron on the performance of Cu-Fe/SiO 2 catalysts for higher alcohols synthesis from syngas were investigated by N 2 adsorption, XRD, H 2 -TPR, CO-IR, XPS, and CO hydrogenation reaction. The results indicate that the catalyst prepared by impregnation of support first with Fe and then with Cu exhibits the highest selectivity (36.1%) and space time yield (153.3 g·kg cat − 1 ·h − 1 ) of alcohols. The CO conversion and alcohol selectivity of the catalysts was closely related to the content of surface Cu, and the ratio of surface contents of Cu to Fe, respectively. [ABSTRACT FROM AUTHOR]

CuO-ZnO-ZrO 2 /HZSM-5 bifunctional catalysts were prepared by a facile route of solid-state reaction and tested for one-step synthesis of dimethyl ether (DME) from CO 2 hydrogenation. The effects of calcination temperature (300–600 °C) on the physicochemical and catalytic properties of the bifunctional catalysts were investigated by XRD, N 2 adsorption, XPS, N 2 O chemisorption, SEM, H 2 -TPR, NH 3 -TPD, and CO 2 -TPD techniques. The results show that both the CO 2 conversion and DME selectivity of the bifunctional catalysts decrease with the increase in calcination temperature, which can mainly be attributed to the decrease of metallic copper surface area ( S Cu ), adsorption capacity of CO 2 , specific surface area, and reducibility of CuO. [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]

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]

Abstract: Rh-Mn-Li catalysts supported on SiO2, ZrO2 and SiO2-ZrO2 mixed oxides with various molar ratios of Si/Zr were prepared and tested for the synthesis of C2-oxygenates from syngas. Compared with pure SiO2 and ZrO2 supported catalysts, catalysts supported on SiO2-ZrO2 mixed oxides showed higher activity and C2-oxygenates selectivity, in which Rh-Mn-Li/SiO2-ZrO2 (molar ratio of Si/Zr=1:3) exhibited the best yield of C2-oxygenates. The effect of the support on the performance of the Rh-based catalysts was investigated comprehensively by XRD, N2 adsorption-desorption, H2 and CO uptakes, FT-IR, XPS, H2-TPR, TPSR and CO-TPD techniques. The results indicated that the chemical state of Rh, CO adsorption species, dispersion of Rh and the ability of CO hydrogenation varied over catalysts supported on SiO2, ZrO2 and SiO2-ZrO2 mixed oxides, which led to the diverse catalytic activity toward C2-oxygenates synthesis. [Copyright &y& Elsevier]

Abstract: The effect of calcination temperature of the monodispersed SiO2 synthesized by the Stöber method on the catalytic performance of Rhph name="sbnd" />Li/SiO2 for CO hydrogenation to C2 oxygenates was investigated. The means of N2 adsorption-desorption, in-situ FT-IR, H2-TPD, H2-TPR, CO-TPD, and TPSR were used to characterize the physico-chemical properties of SiO2 supports and the corresponding Rhph name="sbnd" />Li/SiO2 catalysts. The results showed that the amount of surface Si-OH groups on SiO2 affects the Rh dispersion and Rhction. The increase in the number of Si on the SiO2 was favorable for the Rh dispersion and CO adsorption, further enhanced the activity of the catalyst. In addition, an appropriate amount of surface Si on the SiO2 calcined at 350°C can gain a moderate Rhction. This interaction is conducive to achieve the right hydrogenation ability, which is favorable for the CO insertion into metal-CHx band, and ultimately increases the selectivity of C2 oxygenates. [Copyright &y& Elsevier]

Abstract: Different amounts of Fe promoted Rh–Mn–Li/SiO2 catalysts were prepared and investigated for the synthesis of C2 oxygenates from syngas. The results showed that the low amount of Fe (≤0.1wt.%) improved the reactivity and yield of C2 + oxygenates, but an opposite effect appeared at high content of Fe (>0.1wt.%). Diffuse reflectance infrared Fourier transform spectroscopy was used to probe the effects of Fe on CO adsorption and hydrogenation, and two opposing effects were evidenced. Moreover, it is proposed that the facile transformation of dicarbonyl Rh+(CO)2 into H–Rh–CO is responsible for high selectivity of C2 + oxygenates. [Copyright &y& Elsevier]

Abstract: A novel SiO2 synthesized by the Stöber method was studied as the support for Rh–Mn–Li catalyst, and better performance for C2 oxygenate synthesis via CO hydrogenation was achieved compared with the counterpart using commercial SiO2 as the support. The investigation based on the catalytic performance and characterizations of the catalysts suggests that the hydroxyl–metal interaction over the catalyst supported on SiO2 prepared by the Stöber method results in a change in the CO adsorption on Rh particles, which promotes the CO dissociation and CO insertion, leading to higher CO conversion and C2 oxygenate selectivity. [Copyright &y& Elsevier]

Abstract: SiO2, TiO2 and SiO2–TiO2 mixed oxide were synthesized by sol–gel method and used as supports for Rh-based catalysts. The effect of support on the performance of Rh-based catalysts for C2-oxygenates synthesis from syngas was investigated by XRD, N2 adsorption-desorption, FT-IR, H2-TPD, H2-TPR and TPSR techniques. The results indicated that SiO2–TiO2 supported catalyst had higher dispersion of Rh and thus more Rh+ sites, better capability for CO adsorption and dissociation, and moderate ability for hydrogenation. As a result, SiO2–TiO2 supported Rh-based catalyst exhibited higher activity and C2 oxygenates selectivity compared with counterparts supported on TiO2 and SiO2. [Copyright &y& Elsevier]

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 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]

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]

In this study, a series of Cu–Ce 1-x Zr x O 2 (x = 0, 0.2, 0.5, 0.8, 1) catalysts were prepared by an eco-friendly and facile solid-phase grinding method. The effect of different Ce/Zr molar ratios on the performance of Cu–Ce 1-x Zr x O 2 catalysts for CO 2 hydrogenation to methanol was investigated. The results showed that the Cu–Ce 0.5 Zr 0·5 O 2 catalyst had the best catalytic performance, with CO 2 conversion of 15.2 % and methanol yield of 7.5 % at GHSV = 3600 mL/(g cat ·h)); when GHSV was increased to 20,000 mL/(g cat ·h), the space-time yield of methanol reached 270.8 g CH3OH /(kg cat ·h). X-ray diffraction (XRD), scanning electron microscope (SEM), N 2 adsorption-desorption, N 2 O chemisorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction by H 2 (H 2 -TPR), and temperature programmed desorption (H 2 -TPD, CO 2 -TPD) techniques were used to characterize the catalysts, and the higher reactivity of Cu–Ce 0.5 Zr 0·5 O 2 can be attributed to more Cu0 species, defect oxygen and basic sites. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) results revealed that the hydrogenation of CO 2 to methanol occurred through the formate intermediate pathway. This work proposed an eco-friendly and facile method for the preparation of high-performance Cu-based catalysts and the systematic study provided a deep insight for the development of high-performance Cu-based catalysts for methanol synthesis from CO 2 hydrogenation. [ABSTRACT FROM AUTHOR]

[Display omitted] • An approach to strengthen the boundary role of Pd/CeO 2 catalyst was developed. • Interfacial catalytic activity was investigated by B-TOF and I 0 × B-TOF. • The CO catalytic oxidation mechanism was proposed on the basis of boundary catalysis. Recently, the interface catalysis has caused more and more attentions. Herein, we developed an approach to strengthen the boundary role of Pd/CeO 2 catalyst, resulting in an obvious increase in its catalytic performance for CO oxidatio n with 100% CO conversion at 20 °C. The results show that after the pretreatment in N 2 at 750 °C and reduction in H 2 at 300 °C, the interaction between Pd and CeO 2 was enhanced, and smaller Pd0 particles and longer interface length (I 0) of Pd-CeO 2 were obtained. In the boundary of Pd-CeO 2 , the presence of Pd2+ promotes the formation of oxygen vacancies in CeO 2 , and CO adsorbed on Pd0 reacts with the oxygen species activated by the oxygen vacancy. The Pd0 sites and oxygen vacancies in the boundary play a decisive role in the CO oxidation over Pd/CeO 2 , which is proved by the B-TOF and I 0 × B-TOF. [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]

Abstract: Co/CuZnO is known as a base metal catalyst active for C2+ oxygenate synthesis. This study probed the interactions of the different components of Co/CuZnO catalysts on CO hydrogenation using Fischer–Tropsch synthesis (250°C, H2/CO=2) and SSITKA. Only combination of all three metal components produced a catalyst with relatively high C2+ oxygenate selectivity, but with much lower activity compared to that for Co/Al2O3. In situ reaction characterizations, albeit at somewhat different conditions than alcohol synthesis, helped explain interaction of the components. SSITKA, under methanation conditions, indicated that the most striking feature for the combination of Co with ZnO and/or Cu was a much decreased amount of reaction intermediates. Ethane hydrogenolysis results suggested that the different components for these catalysts were in close contact and few or no large ensembles (n ⩾12) of Co atoms existed, confirming that ZnO and/or Cu covered/blocked a substantial number of active sites on Co for CO hydrogenation. [Copyright &y& Elsevier]