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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]

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]

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]

Density functional theory (DFT+U) was used to study the adsorption of Aux (x = 1–4) clusters on the defective CeO2(111) facet and CO adsorption on the corresponding Aux/CeO2−x catalyst, in this work Aux clusters are adsorbed onto the CeO2−x + superoxide/peroxide surface. When Au1 is supported on the CeO2(111) facet with an O vacancy, the strong electronegative Auδ− formed is not favorable for CO adsorption. When peroxide is adsorbed on the CeO2(111) facet with the O vacancy, Aux was oxidized, resulting in stable Aux adsorption on the defective ceria surface with peroxide, which promotes CO adsorption on the Aux/CeO2−x catalyst. With more Au atoms in supported Aux clusters, CO adsorption on this surface becomes stronger. During both the Au being supported on CeO2−x and CO being adsorbed on Aux/CeO2−x, CeO2 acts as an electron buffer that can store/release the electrons. These results provide a scientific understanding for the development of high-performance rare earth catalytic materials. [ABSTRACT FROM AUTHOR]