Preferential Surface Decoration of Supported Co Catalysts with Pt for Aromatic Saturation

To explore the ideal architecture of Pt-Co bimetallic catalyst for aromatics saturation, various Pt-Co bimetallic catalysts were synthesized via the galvanic replacement, the co-impregnation, and the sequential impregnation methods, and were characterized by CO chemisorption, transmission electron microscopy(TEM), H_2-temperature-programmed reduction(H_2-TPR), H_2-temperature-programmed desorption(H_2-TPD), X-ray fluorescence(XRF) spectrometry, and inductively coupled plasma atomic emission spectroscopy(ICP-AES), while the catalysts were evaluated by the flow reactor study of toluene hydrogenation. These characterization results suggest that the surface decoration of Pt has little influence on the number of active sites located on the surfaces of the reduced Co-based catalysts, but can greatly suppress the oxidation of Co at room temperature and provide the activated hydrogen at a relatively low temperature. It is demonstrated that their chemical properties and catalytic performance are largely dependent on the location of Pt atoms in the bimetallic catalysts. The architecture of Pt-Co bimetallic catalyst consisting of Co/SiO_2 decorated with 0.3% of Pt, with the most of Pt atoms being situated on the surfaces of Co nanoparticles, is the active structure for aromatic saturation and has the maximum utilization of Pt.

Synthesis of Dimethyl Carbonate from CO_2, Methanol, and Epoxides Using Re(CO)_5Cl/K_2CO_3 as Catalyst System

Over the past few years, dimethyl carbonate （DMC） has been proven to be an efficient methylating, methoxylating, and methoxycarbonylating agent in organic syntheses, in which DMC is used to replace the toxic methyl halides, dimethyl sulfate or carbon monoxide, and so forth. Furthermore, DMC has been used in the syntheses of polycarbonates and polyurethane to develop the nonphosgene routes Therefore, DMC has become one of the most important compounds in the development of green synthetic chemistry.

Effect of alcohol solvents treated ZrO(OH)_2 hydrogel on properties of ZrO_2 and its catalytic performance in isosynthesis

A series of ZrO2 catalysts were prepared by treating ZrO（OH）2 hydrogel with different alcohol solvents （C2-C4 alcohols） and calcining under N2 flow at 773 K for 3 h. The obtained ZrO2 catalysts were systematically characterized by the methods of N2 adsorption-desorption, powder X-ray diffraction, NH3 temperature-programmed desorption, and CO2 temperature-programmed desorption. The catalytic performance of each catalyst was evaluated in the selective synthesis of iso-C4 （isobutene and isobutane） and light olefins （C2-C4） from CO hydrogenation. The specific surface area increased for the ZrO2 catalysts obtained by treating ZrO（OH）2 hydrogel with different alcohol solvents. The amounts of both acidic and basic sites on the catalyst surface increased obviously. The catalytic activity （CO conversion） of ZrO2 catalysts also increased after the treatment with different alcohol solvents. The nighest activity was obtained over the catalyst which was pretreated with isopropanol. However, alcohol solvent treatment retarded the transformation of ZrO2 crystal structure from tetragonal phase to monoclinic phase, and subsequently resulted in the decrease of monoclinic phase in ZrO2, which led to the decrease of olefin selectivity in corresponding hydrocarbon products （C2-C4/CH）.

Recent advances on catalysts for preferential oxidation of CO

The trace amount of CO in H2-rich gas poisons Pt electrode when it is adopted as feedstock for proton-exchange-membrane fuel cells.Preferential oxidation of CO(PROX)is a promising approach to selectively oxidize the trace amount of CO while keeping H2 unoxidized.Catalyst plays important roles in PROX.To date,enormous catalysts have been developed for PROX.Summarizing the catalysts developed for PROX and unveiling the reaction mechanism could definitely advance this research field.Herein,in this review,according to the nature of the active sites on the catalysts,we classify the catalysts into group VIII metal-based catalyst,group IB metal-based catalysts,group VIII-group IB bimetallic catalysts,transitional metal oxide catalysts as well as others,describe the progress of the catalysts in PROX in the latest five years,and extract the underlying reaction mechanism,with the aim to provide guidance for the rational design of efficient catalysts in the future.

ReCl（CO）5-catalyzed Reactions of Aromatic Compounds with 1,3,5-Trioxane or Aqueous Formaldehyde Affording Diarylmethanes

ReCl (公司) 5 在空气下面与 1,3,5-trioxane 或水的甲醛(37 wt%) 催化芳香的混合物的脱水反应。与 1,3,5-trioxane 生捐赠电子的组的许多芳香的混合物的反应负担得起相应 diarylmethanes 在对好收益中等。

Synthesis and characterization of monoclinic TiO_(2) nanosheets

A novel two-step method for the synthesis of monoclinic titanium oxide (i.e. TiO2(B)) nanosheets is pre-sented in this report. The method is featured by two steps: 1) synthesis of hydrogen titanate nanosheets, followed by 2) calcination of the titanate nanosheets at elevated tempera-tures. The hydrogen titanate nanosheets were prepared first by autoclaving anatase TiO2 powders, obtained by air cal-cining an ethanol-gel of Ti(OH)4 at 500℃, in aqueous NaOH (10 mol/L) at 150―200℃, and then by washing with hydro-chloric acid under supersonic irradiation. While sizes of the nanosheets were found to increase with increasing the tem-perature of the hydrothermal treatment, the calcination at 400―500℃ of the hydrogen titanate nanosheets that were synthesized at higher autoclaving temperatures (180―200℃) produced monoclinic TiO2 nanosheets with a uniform mor-phology. By contrast, the same calcination of the titanate nanosheets synthesized at the autoclaving temperature 180℃ led to anatase TiO2 nanoparticles.

Heteropolyacid-catalyzed Reaction of Epoxides with Ketones： Efficient Synthesis of 1,3-Dioxolane Derivatives

An efficient method for the preparation of 1,3-dioxolanes via the coupling of epoxides with ketones catalyzed by heteropolyacids at ambient temperature has been described.