双溶剂浸渍法制备VOX/MCF催化剂及丙烷选择氧化

采用双溶剂法制备了负载型氧化钒类催化剂(VOx/MCF),N2物理吸附、X射线衍射、透射电镜、拉曼光谱、程序升温脱附、程序升温还原等系统研究了催化剂的物化性质并测试了其在丙烷选择氧化反应中的催化性能.结果表明,由双溶剂法制备的VOx/MCF催化剂具有较好的催化活性,且在氧化钒负载量基本一致的前提下,双溶剂法制备的VOx/MCF催化剂比普通浸渍法制备的VOx/MCF具有更高的催化活性,这与双溶剂法的制备过程可以使得钒物种尽可能进入载体内表面,有利于氧化钒的较好分散有关,而高度分散的氧化钒物种,正是丙烷选择氧化反应的活性中心.     

沸石和活性炭为载体的Fe3+和Cu2+型催化剂催化氧化苯酚的比较

以沸石和活性炭为载体，制备了Fe3 和Cu2 型沸石和活性炭催化荆，研究了非均相Fe和Cu催化剂催化氧化高浓度含酚废水．在Fenton反应机理的基础上，探讨了Cu2 的均相和非均相催化氧化机理，以人造沸石和活性炭为栽体制备了相应的4种非均相催化剂，进行了均相、非均相Fe和Cu催化剂催化氧化高浓度含酚废水的对比试验，分析了这两种载体的比表面积、孔径分布和中孔孔容，比较了4种非均相催化剂对苯酚降解率的影响．结果发现Cu2 不仅能大大提高反应速率，而且其均相、非均相反应体系的苯酚降解率均可达到约97％．     

Ce-Pt-Pd/不锈钢丝网催化剂的制备与催化性能

采用阳极氧化技术在不锈钢丝网上自生长了一层结构致密的阳极氧化膜,并以此为载体,制备出一种高活性、高稳定性的负载型Ce-Pt-Pd催化剂.考察了该系列催化剂对甲苯、丙酮和乙酸乙酯的氧化活性,并用扫描电镜、X射线光电子能谱和程序升温氧化技术对催化剂进行了表征.结果表明,不锈钢丝网载体表面自生长的氧化物膜十分有利于活性组分的负载,制得的催化剂具有较高的催化燃烧有机化合物的活性和稳定性.     

Au/CuxMnyOz催化剂的制备、表征及其CO消除性能

采用溶胶一凝胶法制各了新型CuxMnyOz:复合氧化物,并利用沉积-沉淀法制各了1%Au/CuxMnyOz:系列催化剂样品,在富H2条件下评价了该催化剂在CO选择性氧化反应和水煤气变换(WGS)反应中的催化性能,结果发现,极少量Au的负载使得CuxMnyOz复合氧化物不仅具有良好的CO氧化活性和选择性,而且在WGS反应...     

微乳液法制备的PtSn/C催化剂对乙醇的电催化氧化性能

以甲酸钠为还原剂,在水/triton X-100/乙二醇/环己烷的W/O型微乳液中制备PtSn/C催化剂.采用X射线衍射（XRD）分析催化剂的结构,循环伏安法和电化学阻抗谱法测试催化剂对乙醇的催化氧化性能.结果表明,微乳法制备的PtSn/C催化剂部分合金化,与Pt/C相比,PtSn/C对乙醇的电催化氧化活性有明显提高,具有更高的抗CO中毒能力.     

Natural hydroxyapatite‐supported MnO2: a green heterogeneous catalyst for selective aerobic oxidation of alkylarenes and alcohols

Natural hydroxyapatite‐supported MnO₂ (MnO₂@NHAp) was easily prepared in situ from reduction of potassium permanganate with natural hydroxyapatite derived from cow bones in water at room temperature, and its structure was characterized using flame atomic absorption spectroscopy, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy and energy dispersive spectroscopy. The catalytic activity of the synthesized catalyst was investigated for the aerobic oxidation of alkylarenes and alcohols. MnO₂@NHAp shows excellent catalytic performance for the oxidation of alkylarenes and alcohols to their corresponding carbonyl compounds without using any other oxidizing agent. This catalyst can be readily recycled and reused for several runs without any significant loss of efficiency. Copyright © 2016 John Wiley & Sons, Ltd.     

Sulfonated carbon catalyzed oxidation of aldehydes to carboxylic acids by hydrogen peroxide

Sulfonated carbon as a strong and stable solid acid catalyst exhibited excellent catalytic performance in various acid-catalyzed reactions. Here, sulfonated carbon, as catalyst for oxidation reaction, was prepared via the carbonization of starch followed by sulfonation with concentrated sulfuric acid. N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray fluorescence and acid-base titration were used to characterize the obtained materials. The catalytic activity of sulfonated carbon was studied in the oxidation of aldehydes to carboxylic acids using 30 wt% H₂O₂ as oxidant. This oxidation protocol works well for various aldehydes including aromatic and aliphatic aldehydes. The sulfonated carbon can be recycled for three times without obvious loss of activity.     

Cobalt-modified nickel–zinc catalyst for electrooxidation of methanol in alkaline medium

Cobalt-modified nickel-zinc catalyst CuNi(Zn)Co is prepared on a copper substrate by using electrodeposition. Its catalytic efficiency for methanol oxidation is studied with cyclic voltammetry, chronoamperometry, and chronopotentiometry techniques. The surface morphology and chemical composition of catalyst are characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The oxidation kinetic parameters activation energy (Ea), active species on the surface (Γ), and rate constant (k) are determined from cyclic voltammograms which are performed at different methanol concentrations and temperatures. The results show that Ni(Zn)Co catalyst has higher catalytic activity than Ni, Co, and NiZn coatings as a composite catalyst for a promising choice of methanol electrooxidation in the alkaline medium.     

Chlorine dioxide catalytic oxidation and online FTIR spectroscopic analysis of simulated o-chlorophenol wastewater

An activated carbon-MnO₂ catalyst was prepared and used for chlorine dioxide catalytic oxidation of simulated o-chlorophenol wastewater. The COD removal efficiencies of chemical oxidation and catalytic oxidation are 28.6 and 93.5%, respectively. The COD removal efficiency of catalytic oxidation is greater than that of chemical oxidation at the same treatment condition. By using UV?CVis and online FTIR analysis technique, the intermediates during the degradation process were obtained. The benzene ring in o-chlorophenol was degraded into quinone and carboxylic acid, and finally changed into carbon dioxide and water during the catalytic oxidation. The degradation reaction mechanism of o-chlorophenol by chlorine dioxide catalytic oxidation was proposed based upon the experiment evidence.     

Catalytic partial oxidation of methane to synthesis gas over a ruthenium catalyst: the role of the oxidation state

The catalytic partial oxidation of methane to synthesis gas over ruthenium catalysts was investigated by thermogravimetry coupled with infrared spectroscopy (TGA-FTIR) and in situ X-ray absorption spectroscopy (XAS). It was found that the oxidation state of the catalyst influences the product formation. On oxidized ruthenium sites, carbon dioxide was formed. The reduced catalyst yielded carbon monoxide as a product. The influence of the temperature was also investigated. At temperatures below the ignition point of the reaction, the catalyst was in an oxidized state. At temperatures above the ignition point, the catalyst was reduced. This was also confirmed by the in situ XAS spectroscopy. The results indicate that both a direct reaction mechanism as well as a combustion-reforming mechanism can occur. The importance of knowing the oxidation state of the surface is discussed and a method to determine it under reaction conditions is presented.     

纳米孔炭负载 MnOx 催化剂上苯甲醇氧化反应性能

 以纳米孔炭 (NC) 为载体, 采用浸渍法制备了一系列 MnOx/NC 催化剂, 并用于以空气为氧源的苯甲醇液相氧化反应. 通过 X 射线衍射、X 射线光电子能谱、N2 吸附-脱附和 H2-程序升温还原等手段对催化剂进行了表征, 考察了催化剂中 Mn 负载量和焙烧温度, 以及反应条件等对反应性能的影响. 结果表明, 10%MnOx/NC 催化剂的活性较高, 反应 4 h 后苯甲醇转化率可达 80.4%; 明显高于活性炭负载的 MnOx 催化剂. 这主要归因于其表面存在大量高分散、且易于还原的 Mn 物种.     

Highly efficient oxidative cleavage of alkenes and cyanosilylation of aldehydes catalysed by magnetically recoverable MIL‐101

The catalytic activity of magnetically recoverable MIL‐101 was investigated in the oxidation of alkenes to carboxylic acids and cyanosilylation of aldehydes. MIL‐101 was treated with Fe₃O₄ and the prepared catalyst was characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, N₂ adsorption measurements, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and inductively coupled plasma analysis. The catalytic active sites in this heterogeneous catalyst are Cr³⁺ nodes of the MIL‐101 framework. This heterogeneous catalyst has the advantages of excellent yields, short reaction times and reusability several times without significant decrease in its initial activity and stability in both oxidation and cyanosilylation reactions. Its magnetic property allows its easy separation using an external magnetic field.     

Au/SBA-15 的制备及其催化 CO 氧化反应性能

 以 SBA-15 为载体, 采用沉积沉淀法制备了纳米 Au 催化剂, 研究了不同预处理条件对 Au 在载体表面状态的影响, 考察了催化剂样品催化 CO 氧化性能. 以高分辨率透射电子显微镜、N2 吸附、X 射线衍射、紫外-可见漫反射吸收谱、X 射线光电子能谱和电感耦合等离子体发射光谱等手段对催化剂的结构和表面性质进行了表征. 结果表明, 经还原焙烧处理后的 Au/SBA-15 催化剂热稳定性较好, Au 在 SBA-15 孔道表面呈高分散状态, 样品在 CO 氧化反应中表现出优异的低温催化活性和高温稳定性, 同时具有优异的抗烧结性能和良好的循环稳定性.     

醋酸溶液中Pd-CuPc/Y催化甲烷选择氧化制甲醇

以氯化铜、钼酸铵、苯酐、氯化铵、尿素和NaY分子筛为原料,采用苯酐-尿素法制备了酞菁铜/分子筛复合物CuPc/Y.采用等体积浸渍法将金属钯担载在CuPc/Y上制备了Pd-CuPc/Y催化剂,并在醋酸水溶液中考察了其催化甲烷选择氧化合成甲醇反应的性能,结果表明,催化性能与反应温度、溶剂中CH₃COOH与H₂O的混合比例、对苯醌用量、反应时间等因素有关,在0.5%Pd-0.5%CuPc/Y添加量0.5 g、CH₃COOH与H₂O体积比4∶1、对苯醌用量1 000 μmol、反应时间3 h、反应温度150 ℃的条件下,甲醇的最佳生成量为1 840 μmol.Pd-CuPc/Y催化剂可以多次循环使用,但由于催化剂流失和催化剂表面的钯粒子聚集的原因,循环使用后的催化剂催化活性有所下降.Pd-CuPc/Y在醋酸溶液中催化甲烷选择氧化合成甲醇是亲电取代反应和活性氧物种氧化共同作用的结果.     

壳聚糖修饰炭黑负载Pt-Au催化剂对甲醇氧化的电催化性能

以炭黑及自制的壳聚糖-炭黑(CHI-C)复合材料为载体,采用溶胶负载法制备了Pt_m＾Au/C及Pt_m＾Au/CHI-C催化剂(＾ 代表Au、Pt为分步负载,m代表Pt/Au原子比),通过紫外-可见吸收光谱、X射线衍射、透射电镜及X射线光电子能谱对催化剂进行了表征。利用循环伏安法和计时电流法分别测定了Pt-Au催化剂对甲醇电催化氧化反应的活性和稳定性,考查了Pt/Au原子比及CHI改性对电催化活性和稳定性的影响。结果表明,Pt_1.0＾Au/C具有最高的催化活性,炭黑中加入少量CHI能提高Pt_1.0＾Au/C催化剂的稳定性。     

PtTe/C催化剂的制备及其对乙醇的电催化氧化性能

采用无机溶胶法制备了用于乙醇燃料电池的PtTe/C催化剂;利用X射线衍射仪分析了催化剂的结构,采用循环伏安法和电化学阻抗法测试了PtTe/C催化剂对乙醇的电催化氧化性能.结果表明,与商业Pt/C催化剂相比,PtTe/C催化剂对乙醇的催化氧化效率明显较高,可使乙醇氧化峰电流密度提高27%,且具有更高的抗CO中毒能力.     

TiO2负载Pt对光催化去除低浓度NO性能的影响

以溶胶-凝胶法以及湿式浸渍法制备了Pt/TiO2催化剂,采用了XRD、BET、UV-vis、TEM、XPS等方法进行表征,并进行了对NO的催化氧化性能测试.结果表明铂的负载能显著提高TiO2光催化剂对NO的氧化转化能力和去除率.0.5%Pt/TiO2对NO的氧化率与去除率分别为45.0%和38.1%,与纯锐钛矿TiO2(13.6%,10.7%)相比,氧化效率提高3.3倍,去除效率提高3.6倍.通过比较不同方法制备的负载Pt催化剂的活性,初步讨论了催化剂表面发生的反应机理:铂氧化物以及催化剂表面吸附的O2分子通过与光生电子和光生空穴结合,产生了强氧化性自由基,将NO氧化得到NO2.     

Influence of the Time Scale on the Reaction Mechanism of CO Oxidation over a Au/TiO2 Catalyst

Knowledge of the reaction mechanism is key for rational catalyst improvement. Traditionally mechanistic studies focus on structure and the reaction conditions like temperature, pH, pressure, etc., whereas the time dimension is often overlooked. Here, we demonstrate the influence of time on the mechanism of a catalytic reaction. A dual catalytic mechanism was identified for the CO oxidation over Au/TiO₂ by time-resolved infrared spectroscopy coupled with modulation excitation spectroscopy. During the first seconds, CO on the gold particles is the only reactive species. As the reaction proceeds, the redox properties of TiO₂ dominate the catalytic activity through electronic metal-support interaction (EMSI). CO induces the reduction and reconstruction of TiO₂ whereas oxygen leads to its oxidation. The activity of the catalyst follows the spectroscopic signature of the EMSI. These findings demonstrate the power of studying short-time kinetics for mechanistic studies.     

Keggin结构多阴阳离子构筑高活性多酸基氧化脱硫催化剂

设计开发高活性超深度氧化脱硫催化剂是解决未来石化工业适应日益严格要求的清洁燃油标准的重要出路之一。本文合成了Keggin结构多聚铝阳离子烷基硫酸盐Al_13-SDS和磷钨酸(HPW)多阴离子构筑的催化剂HPW-Al_13-SDS(SDS=十二烷基硫酸钠),采用傅里叶红外光谱(FT-IR)、紫外可见光谱(UV-Vis)、热重分析(TG)、X射线衍射(XRD)和Brunauer-Emmett-Teller(BET)等测试手段对催化剂的结构进行表征。FT-IR和UV-Vis的表征结果表明,焙烧后的催化剂中多聚铝阳离子和HPW同时保持Keggin骨架结构。以有机硫二苯并噻吩(DBT)的正己烷溶液为模拟油品的氧化脱硫为探针反应,在选定的条件下,DBT有机硫的脱除率达到99.5%。反应后HPW-Al_13-SDS催化剂的FT-IR和XRD的表征证实产生过氧化多钨酸化合物。催化剂能够循环使用,易分离,循环使用后活性未见明显降低,是理想的模型有机硫化物氧化脱除用催化剂。     

Preparation and Characterization of Ni‐Modified Graphene Oxide Complex as an Efficient Catalyst for the Synthesis of Sulfides via Reaction of Arylhalides with S8 or Thiourea

In this work, complex of Ni‐modified graphene oxide was prepared and characterized using FT‐IR spectroscopy, SEM, XRD, TGA and ICP‐OES techniques. This compound used as an efficient and recoverable catalyst for the C–S coupling reaction using sulfur‐transfer reagents (S₈ or thiourea). The catalyst was easily separated using a simple filtration and reusable without significant loss of their catalytic efficiency.