Silica-Supported Gold Catalyst Modified by Doping with Titania for Cyclohexane Oxidation

Amorphous silica was modified by doping with titania through a surface sol–gel process and applied as the support for depositing gold. These doped silica-supported gold catalysts were tested in the selective cyclohexane oxidation to cyclohexanone and cyclohexanol using oxygen. Under the oxidation conditions of 150 °C, 1.5 MPa and 3 h, a selectivity of 91.7% for cyclohexanone and cyclohexanol could be reached over the gold catalyst, affording a cyclohexane conversion of 8.4% and a turnover frequency up to 40,133 per hour. Moreover, the catalytic activity and selectivity could be well retained in 4 recycling oxidation reactions, showing a high stability of the gold catalyst supported on titania-doped silica.     

Ultrahigh Durable PtPd/C Nanowire Networks Catalyst Synthesized by Modified Phase Transfer Method for Methanol Oxidation

A novel PtPd/C nanowire catalyst with interconnected network and fewer great grain boundaries has been successfully prepared by templateless and modified phase‐transfer method using cetyltrimethylammonium bromide as a capping in ethylene glycol solution by microwave‐assisted process. Its structure, composition, and morphology are characterized by X‐ray diffraction, energy dispersive analysis of X‐ray, and transmission electron microscopy, respectively. The electrochemical measurements demonstrate that the highly dispersed and uniform PtPd/C nanowire networks catalyst has a significantly higher electrocatalytic activity and durability for the methanol oxidation as compared to solid solution PtPd/C. The greatly improved durability of PtPd/C nanowire networks catalyst is mainly a consequence of the unique interconnected network structure with fewer grain boundaries, which provide more facile pathway for the electron transfer, and inhibit the particle growth and agglomeration, as well as prevent the particles embedded in the microporous of carbon support to enhance the Pt utilization.     

微波法煅烧硫酸工业钒催化剂

研究了微波法煅烧硫酸工业用矾催化剂，获得了最佳工艺操作参数，包括微波功率和辐射时间。微波法煅烧矾催化剂的催化活性、机械强度、磨损率和结构性能均达到并超过传统法的指标。此外，微波法还较大幅度地节省能耗，缩短反应时间，减少环境污染，降低成本，提高经济效益。     

Post‐Plasma Catalysis for Methane Partial Oxidation to Methanol: Role of the Copper‐Promoted Iron Oxide Catalyst

Methane‐air partial oxidation to methanol over a ceramic‐supported Fe₂O₃‐CuO catalyst was investigated in a post‐plasma catalytic reactor at ambient conditions. The multicomponent catalyst exerted a better catalytic performance than the monocomponent Fe₂O₃ catalyst. Characterization of the catalysts by XPS showed that incorporation of the CuO additive to a Fe₂O₃‐based catalyst resulted in an increase of lattice oxygen in the surface of the catalyst which facilitated selective methane oxidation. Hydrogen temperature‐programmed reduction revealed that addition of the CuO promoter could improve the reduction performance of the catalyst. Moreover, this catalyst showed excellent stability and resistance against carbon deposition in the extended reactions while maintaining catalytic activity. A post‐plasma catalytic mechanism is proposed with three main pathways to methanol synthesis.     

沉积-沉淀法制备金催化剂用于CO催化氧化

采用沉积-沉淀法制备了一种介孔氧化铝负载的金催化剂用于CO的低温催化氧化,详细考察了催化剂制备条件、干燥条件和热处理条件对其催化性能的影响。采用X射线粉末衍射(XRD)、透射电镜(TEM)、低温N2物理吸附(N2-BET)、电感耦合等离子发射光谱(ICP-AES)和紫外-可见漫反射(Uv-vis DRS)对催化剂进行了表征。结果表明,通过严格控制催化剂的制备条件、干燥条件和热处理条件,可以在惰性氧化铝载体上高重复性可控合成具有高分散度的金催化剂,金颗粒最佳平均粒径为2 nm,体现出良好的CO低温催化氧化性能。     

从废弃甲醇合成催化剂中回收氯化亚铜和氧化锌的新工艺研究

国内甲醇产能约3000万t/a,可综合利用的废弃甲醇合成催化剂约3000t/a,笔者研究了一种从废弃甲醇合成催化剂中回收氯化亚铜和氧化锌的新工艺.简述了回收氯化亚铜和氧化锌的制备原理;论述了废弃催化剂的预处理工艺条件以及浸取制备氯化亚铜和氧化锌的工艺条件.研究结果表明:回收的氯化亚铜产品质量可达到GB1619-79中标...     

Mesoporous Zn–Ti Mixed Oxide Nanostructure: A New Bifunctional Catalyst for Partial Oxidation and Bezylation Reactions

Here, we report a facile synthesis of porous zinc-titanium oxide based mixed oxide nanoparticles having Zn/Ti molar ratio 1:2 based on evaporation-induced sol–gel route using Pluronic triblock copolymer P123 as a template. Use of volatile ethanolic media during the evaporation-induced self-assembly (EISA) method facilitates the formation of Zn–Ti mixed oxide heterostructure. Powder XRD data reveals that the composite material displayed ZnTiO₃/TiO₂ phases. Morphology, composition, porosity, nanostructure and thermal stability have been systematically investigated using small angle powder XRD, FE SEM-EDS, TEM, N₂ sorption, FT IR and TG-DTA techniques. The observed BET surface area of Zn–Ti mixed oxide was 231 m² g^?1 with a typical mesopore diameter (~?5 nm) mostly arising from interparticle void space. The Zn–Ti mixed oxide catalyst showed bifunctional activity for Friedel–Craft benzylation of aromatics using benzyl chloride as well as partial oxidation of olefins under mild reaction conditions using dilute aqueous H₂O₂ as oxidant.

Graphical Abstract

Zn–Ti based porous nanoparticles synthesized using Pluronic P123 copolymer surfactant via EISA method has shown a very high surface area of 231 m² g^?1 and a significant bifunctional role for liquid phase oxidation and benzylation reaction.

     

载体对Au-Pd催化剂甲醇部分氧化制氢性能的影响

用PVP保护乙醇还原法制备了一系列Au-Pd/MOx(M=Zn、Ce、Fe、Ti、Cr和Al)双金属催化剂,考察了不同载体对Au-Pd催化剂甲醇部分氧化制氢性能的影响,用XRD、TG、TPD、TPR和TPH等对催化剂进行了表征。结果表明,载体对催化剂性能有较大影响,与钛、铬和铝氧化物载体相比,448K时偏碱性的锌、铈和铁氧化物载体负载的Au-Pd催化剂的甲醇转化率均在80.0%以上,催化剂积碳量降低。其中以Au-Pd/ZnO催化剂的效果最好,523K时甲醇转化率和氢气选择性分别为99.0%和45.6%,反应20h后积碳量仅为0.0232g/gcat.。     

Synthesis of Vanadium Phosphate Catalysts by Hydrothermal Method for Selective Oxidation of n-butane to Maleic Anhydride

Two vanadium phosphate catalysts (VPH1 and VPH2) prepared via hydrothermal method are described and discussed. Both catalysts exhibited only highly crystalline pyrophosphate phase. SEM showed that the morphologies of these catalysts are in plate-like shape and not in the normal rosette-type clusters. Temperature-programmed reduction in H₂ resulted two reduction peaks at high temperature in the range of 600–1100 K. The second reduction peak appeared at 1074 K occurred as a sharp peak indicated that the oxygen species originated from V⁴⁺ phase are having difficulty to be removed and their nature are less reactive compared to other methods of preparation. Modified VPH2 gave better catalytic performance for n-butane oxidation to maleic anhydride contributed by a higher BET surface area, high mobility and reactivity of the lattice oxygen associated to the V⁴⁺ which involved in the hydrocarbon’s activation. A slight increased of the V⁵⁺ phase also enhanced the activity of the VPH2 catalyst.     

氧化锰改性氧化硅负载金催化剂的制备及其对苯甲醇的选择性催化氧化

为实现醇的高效气相选择性氧化,以四氧化三锰改性氧化硅为载体制备了负载型金催化剂。结果表明,催化剂载体经过四氧化三锰改性后,催化剂催化活性明显提高,当反应温度为250℃时,苯甲醇的转化率及产物苯甲醛的选择性可分别达到96%和98%。采用X射线粉末衍射(XRD)和透射电镜(TEM)对催化剂进行了表征,结果表明,低负载量的四氧化三锰在氧化硅表面实现了单层分散。由于金和单层分散的四氧化三锰之间的相互作用,使该催化剂体现出良好的醇气相选择性催化氧化性能。     

Study on the Reaction Mechanism for Soot Oxidation Over TiO2 or ZrO2-supported Vanadium Oxide Catalysts by Means of In-situ UV-Raman

The reaction mechanisms for diesel soot oxidation over V₄/ZrO₂ or V₄/TiO₂ oxide catalysts were studied by the means of in-situ UV-Raman spectroscopy. The results indicate that the formation of surface oxygen complexes (SOC) is a key step and the SOC species mainly exist as carboxyl groups. The presence of NO in the reaction gas stream can promote the formation of SOC species. For soot oxidation over V₄/TiO₂ catalyst, NO₂ can be produced and remarkably accelerate soot oxidation. Based on the UV-Raman experimental results, two different reaction mechanisms are proposed for soot oxidation over V₄/ZrO₂ or V₄/TiO₂ samples, respectively.     

Co-precipitated Copper Zinc Oxide Catalysts for Ambient Temperature Carbon Monoxide Oxidation: Effect of Precipitate Aging Atmosphere on Catalyst Activity

A study of the effect of the aging atmosphere on the activity of co-precipitated copper zinc oxide catalysts for the ambient temperature oxidation of carbon monoxide is described and discussed. Four aging atmospheres are reported: air, N₂, H₂ and CO₂, and both the precipitation and the aging of the precipitate were carried out by flowing these gases through the precipitation cell at constant pH and temperature. For all atmospheres, the surface area of the final CuO-ZnO catalyst increases with aging time and, consequently, the specific activity (mol CO converted/g catalyst/h) also increases. However, the intrinsic activity (mol CO converted/m²/h) initially decreases with aging time before attaining a steady level. The highest activity catalysts were obtained using air as the aging atmosphere and TPR studies indicate that this catalyst is less readily reduced. Catalysts prepared using CO₂ as the aging atmosphere have lower activity, although the surface areas of these catalysts are not markedly lower. The study demonstrates that selection of the appropriate aging atmosphere, as well as the aging time, is an important parameter for the preparation of co-precipitated catalysts.     

Nanocrystalline Magnesium Oxide Stabilized Palladium(0): An Efficient Reusable Catalyst for Room Temperature Selective Aerobic Oxidation of Alcohols

Nanocrystalline magnesium oxide‐stabilized palladium(0) [NAP‐Mg‐Pd(0)], as an efficient catalytic system has been employed for the selective oxidation of alcohols using atmospheric oxygen as a green oxidant at room temperature. Various alcohols could be transformed into their corresponding aldehydes or ketones in good to excellent yields using a set of optimal conditions. NanoActive™ Magnesium Oxide Plus, [NAP‐MgO] with its three‐dimensional structure and well‐defined shape acts as an excellent support for well dispersed palladium(0) nanoparticles. This catalyst can be recovered and reused for several cycles without any significant loss of catalytic activity.     

Perovskite-type Oxide LaMnO3: An Efficient and Recyclable Heterogeneous Catalyst for the Wet Aerobic Oxidation of Lignin to Aromatic Aldehydes

The perovskite-type oxide catalyst LaMnO₃ prepared by the sol–gel method was found to be an efficient heterogeneous and recyclable catalyst for the wet aerobic oxidation of lignin to aromatic aldehydes. The lignin conversion rate and the yield of each aromatic aldehyde were enhanced significantly by the catalytic process as compared with the non-catalyzed process. Moreover, the activity, specific surface area and perovskite-type structure of the LaMnO₃ catalyst remained nearly unchanged after five successive recycles of catalytic reactions.     

应用4-DMAP催化合成乙酸薄荷酯的新方法

使用 4 -二甲基氨基吡啶 ( 4 -Dimethylaminopyridine ,4 -DMAP)催化剂合成乙酸薄荷酯 ,工艺简单 ,反应收率达 95 %以上 ,适于工业化生产。用该催化剂合成乙酸薄荷酯的方法尚未见有文献报道     

Deposition of Gold Particles on Mesoporous Catalyst Supports by Sonochemical Method, and their Catalytic Performance for CO Oxidation

Supported gold catalysts on the mesoporous (MSP) metal oxides were prepared by a one-step, ultrasound-assisted reduction method, and characterized by XRD, HRTEM, EDX, BET, and XPS analysis. Their catalytic activities were examined in the oxidation of CO. Compared to the Au/Fe₂O₃(MSP) catalyst, the Au/TiO₂(MSP) and Au/Fe₂O₃-TiO₂(MSP) catalysts exhibited higher catalytic activity in the oxidation of CO at low temperatures. The high catalytic activity of Au/TiO₂(MSP) was attributed to the metallic state of the gold nanoparticles, their small size (2–2.5 nm), and their high dispersion on the catalyst support.