Effect of the Preparation Conditions of Ru/CeO2 Catalysts for the Liquid Phase Oxidation of Benzyl Alcohol

Ceria colloidal particles with a mean crystallite size of 2 nm were synthesized by a solvothermal reaction. The Ru/CeO₂ catalyst prepared from the CeO₂ colloids exhibited higher activity than the catalyst prepared from Ce(NO₃)₃. Temperature-programmed reduction analysis indicated that the reduction of surface Ce⁴⁺ was accelerated by highly dispersed Ru species on the CeO₂ particles and occurred at low temperatures. The single component CeO₂ sample prepared by the coagulation of the CeO₂ colloid was more easily reduced and re-oxidized than the CeO₂ sample prepared by the precipitation method from Ce(NO₃)₃. The higher activity of Ru/CeO₂ prepared from the CeO₂ colloids came from the inherent nature of the CeO₂ support itself.     

Base-Free Benzyl Alcohol Aerobic Oxidation Catalyzed by AuPdNPs Supported on SBA-15 and TiO2/SBA-15 Mesoporous Materials

Catalysis Letters - It is known that the oxidative reactions of alcohols are sensitive to the characteristics of the catalyst, in such a way that the properties of the support are as important as...     

Selective Oxidation of Benzyl-Alcohol over Biomass-Supported Au/Pd Bioinorganic Catalysts

We report a novel biochemical method based on the sacrificial hydrogen strategy to synthesise bimetallic Au/Pd nanoparticles supported on bacterial cells. The synergistic effect of Au/Pd over monometallic preparations was demonstrated in the oxidation of benzyl alcohol. The bioinorganic catalysts outperformed a commercial Pd catalyst (5% Pd/C) showing no deactivation and high selectivity towards benzaldehyde.     

Effect of Water Vapor on Carbon Monoxide Oxidation over Promoted Platinum Catalysts

The catalytic behavior of the two kinds of Pd/SiO₂ catalysts prepared from dinitrodiamminepalladium and palladium nitrate are compared for ethene hydroformylation and carbon monoxide hydrogenation. The catalyst prepared from dinitrodiamminepalladium, on which very fine particles of Pd were observed, showed high activity for ethene hydroformylation. On the other hand, the catalyst prepared from palladium nitrate, on which relatively large particles of Pd were observed, showed high activity for CO hydrogenation.     

Vapor phase esterification of levulinic acid over ZrO2/SBA-15 catalyst

ZrO₂/SBA-15 catalysts with different ZrO₂ loadings prepared by impregnation method were tested for the esterification of levulinic acid in a fixed-bed reactor in vapor phase conditions at atmospheric pressure for the first time and found that the catalyst with 7 weight percent ZrO₂ exhibited 100% conversion of levulinic acid and 96% selectivity to methyl levulinate due to the presence of more number of moderate acidic sites. It is interesting to observe the formation of γ-valerolactone as the alcohol chain length increases at the expense of alkyl levulinate, through MPV reduction mechanism.     

Bi2O3电极的制备及其选择性氧化苯甲醇性能研究

采用滴凃法和电沉积法制备了Bi2O3薄膜电极,运用场发射扫描电子显微镜和X射线衍射仪对其进行了表征。在水相中以苯甲醇选择性氧化合成苯甲醛为模型反应,研究Bi2O3薄膜的催化性能。其中电沉积法制备的Bi2O3薄膜电极在水相溶液中表现出优异的电催化选择性氧化性能,苯甲醇的转化率最高,并且在外加偏压为2 V时达到了最高的苯甲醛选择性和苯甲醛收率。     

Preparation of Promoted Pt/SBA-15 and Effect of Cerium on the Catalytic Activity over Carbon Monoxide Oxidation Conversion Reaction

Pt/SBA-15 catalysts are modified by cerium dopant and agent. Experimental results show that the catalytic activities of Pt/SBA-15 can be deeply promoted by the introduced cerium species, especially while both cerium dopant and cerium agent are introduced. The promoted catalytic activities are due to the occurrence of new coordination environments, promoted physicochemical properties of Pt loading created by both introduced cerium species, and the strong metal-support interactions created by the cerium loading.     

Eco-Friendly Vapor Phase Aerobic Selective Oxidation of Styrene to Benzaldehyde Over SBA-15 Supported Vanadium Modified Heteropolyacid Catalyst

Catalysis Letters - Selective oxidation of styrene to benzaldehyde was investigated over H4PMo11VO40 (HPMoV) supported on SBA-15 support in eco-friendly aerobic gas phase condition. A series...     

Selective Photo-Assisted Oxidation of Methane into Formaldehyde on Mesoporous VO x /SBA-15 Catalysts

Mesoporous VO _x /SBA-15 samples have been prepared by different impregnation methods, characterized by N₂ adsorption and diffuse reflectance UV–visible spectroscopy, and their photocatalytic reactivity evaluated for the selective oxidation of methane with oxygen at 220 °C under UV irradiation. Vanadium in dehydrated VO _x /SBA-15 samples was found to be predominantly as isolated four-coordinated V⁵⁺ species, especially at V loading below 2.5 wt%. VO _x /SBA-15 catalysts prepared by impregnation with an aqueous solution of ammonium metavanadate (AMV) showed a maximum rate of formation of formaldehyde of 525 mol g^-1 h^-1 (selectivity of 93.8 mol%) at a vanadium content of 2.65 wt%. Both the rate of formation and selectivity of formaldehyde were improved when vanadium was impregnated on the SBA-15 support from a vanadyl sulfate methanolic solution (rate of formation of HCHO = 733 mol g^-1 h^-1, selectivity = 95.4 mol%). VO _x /SBA-15 catalysts were seen to be more effective for the selective photo-assisted oxidation of methane than VO _x /SiO₂ catalysts.     

制备参数对Au/TiO_2催化剂上CO低温氧化性能的影响

以溶胶-凝胶法制备TiO2载体,用沉积-沉淀法制备出一系列负载型Au/TiO2。系统考察了焙烧温度、金的负载量、反应液pH值、沉淀剂种类以及Cl-存在与否等制备参数对催化剂活性的影响。以室温下CO的催化氧化为探针反应,确定催化剂的最适宜制备参数,并对优化的质量分数为1.0%的Au/TiO2催化剂进行了活性稳定性测试。结果表明：Au/TiO2的最适宜焙烧温度是200～350℃;反应液的最适宜pH值为9;最适宜沉淀剂是NaOH;金的负载量（质量分数,下同）在0.5%～5.0%范围内时,金含量越高,催化剂活性和热稳定性越好。大量Cl-的存在能导致催化剂活性的显著下降。对优化的Au/TiO2催化剂在室温下催化氧化不同浓度的CO进行循环测试,经历3次循环,连续反应2 160 min后,CO的转化率仍为100%。     

Liquid‐Phase Aerobic Oxidation of Benzyl Alcohol Catalyzed by Pt/ZrO2

The oxidation of benzyl alcohol by molecular oxygen in the liquid phase and catalyzed by Pt/ZrO2 using n‐heptane as the solvent was studied. Pt/ZrO₂ was very active and 100 % selective for benzyl alcohol conversion to benzaldehyde. The catalyst can be separated by filtration and reused. No leaching of Pt or Zr into the solution was observed. Typical batch reactor kinetic data were obtained and fitted to the Langmuir‐Hinshelwood, Eley‐Rideal and Mars‐van Krevelen models of heterogeneously catalyzed reactions. The Langmuir‐Hinshelwood model was found to give a better fit. The rate‐determining step was proposed to involve direct interaction of an adsorbed oxidizing species with the adsorbed reactant or an intermediate product of the reactant. H₂O₂ was also proposed to be an intermediate product. n‐Heptane was found to be an appropriate solvent in this reaction system.     

Supported Nano-Gold Catalysts for Epoxidation of Styrene and Oxidation of Benzyl Alcohol to Benzaldehyde

Nano-gold particles supported on different alkaline earth oxides (viz. MgO, CaO, BaO and SrO), Gr. IIIa metal oxides (viz. Al₂O_3, Ga₂O_3, In₂O₃ and Tl₂O₃), transition metal oxides (viz. TiO_2, Cr₂O_3, MnO_2, Fe₂O_3, CoO_x, NiO, CuO, ZnO, Y₂O₃ and ZrO₂), rare earth metal oxides (viz. La₂O_3, Ce₂O_3, Nd₂O_3, Sm₂O_3, Eu₂O_3, Tb₂O_3, Er₂O₃ and Yb₂O₃) and U₃O₈ [all prepared by depositing gold on corresponding metal oxide support by deposition precipitation (DP) and/or homogeneous deposition precipitation (HDP) method] were evaluated for their catalytic performance in the liquid phase epoxidation of styrene by tert-butyl hydroperoxide (TBHP) to styrene oxide and also in the solvent-free benzyl alcohol-to-benzaldehyde oxidation (by molecular oxygen or TBHP) reactions. For the epoxidation, the catalytic performance (styrene oxide yield) of the most promising nano-gold catalysts prepared by the HDP method was in the following order: Au/MgO > Au/Tl₂O₃ > Au/Yb₂O₃ > Au/Tb₂O₃ > Au/CaO (or TiO₂). However, for the oxidation of benzyl alcohol to benzaldehyde by molecular oxygen, the order of choice for the most promising catalysts (based on benzaldehyde yield) was Au/U₃O₈ > Au/Al₂O₃ > Au/ZrO₂ > Au/MgO. Whereas, when TBHP was used as an oxidizing agent for the benzyl alcohol oxidation, the order of choice for the most promising catalysts was Au/U₃O₈ > Au/MgO > Au/TiO₂ > Au/ZrO₂ > Au/Al₂O₃. The catalytic performance of a particular supported nano-gold catalyst was thus found to depend on the reaction catalysed by them. Moreover, it is strongly influenced by a number of catalyst parameters, such as the metal oxide support, the method of gold depositon on the support, the gold loading and also on the catalyst calcination temperature. Nano-gold particles-support interactions seem to play an important role in controlling the deposition of gold (amount of gold deposited and size and morphology of gold particles), formation of different surface gold species (Au⁰, Au¹⁺ and Au³⁺) and electronic properties of gold particles and, consequently, control the catalytic performance (both the activity and selectivity) of the supported nano-gold catalysts in the reactions. The nano-gold catalysts prepared by the HDP method showed much better catalytic performance than those prepared by the DP, coprecipitation or impregnation method; in general, the HDP method provided supported gold catalysts with much higher gold loading and/or smaller size gold particles than that achieved by the DP and other methods.     

SBA-15微球负载Karstedt催化剂制备及对硅氢加成反应动力学

以三嵌段共聚物P123(EO20PO70EO20)为模板剂、正硅酸乙脂(TEOS)为硅源、氯化氢(HCl)为催化剂,通过水热法制备了介孔Si O2(SBA-15)微球,并以之为载体,制备了SBA-15负载Karstedt催化剂。通过扫描电子显微镜、小角X射线衍射、透射电子显微镜、氮气等温吸附–脱附实验等对催化剂形貌和结构进行表征。结果表明:催化剂直径为2~4μm,该微球具有高度有序二维贯通介孔结构,最可几孔径分布为4.5 nm,比表面积高达628 m2/g。以1-十八烯和三甲氧基硅烷硅氢加成反应为探针反应,研究了不同温度下催化剂的催化性能。当催化剂用量为反应物质量的5%、反应温度为80℃、反应时间为5 h时,1-十八烯转化率可达67.2%,反应活化能为9.176 k J/mol。     

Preparation,Structure Characterization and Hydrodesulfurization Performance of B-Ni2P/SBA-15/Cordierite Monolithic Catalysts

A series of B-Ni2P/SBA-15/cord monolithic catalysts were prepared by coating the slurry of the B-Ni2P/SBA-15 precursors on a pretreated cordierite support, and followed by temperature-programmed reduct...     

Highly Active Au/TiO2 Catalysts for Low-Temperature CO Oxidation: Preparation, Conditioning and Stability

Using a modified depositionprecipitation procedure and a new reductive conditioning method, Au/TiO₂ catalysts with small metallic Au particles (<2 nm) and a very high activity for low-temperature CO oxidation were prepared. The particles are stable during reaction; a decreasing activity is caused by the accumulation of by-products on the catalyst.