SBA-15负载钒氧化物催化剂上甲烷选择氧化反应

对SBA 15负载的钒、钼、钨氧化物催化的甲烷选择氧化反应性能进行了比较 ,发现VOx/SBA 15催化剂优于MoOx/SBA 15和WOx/SBA 15催化剂 .针对钒氧化物催化剂 ,考察了不同钒源、不同载体以及少量P元素的添加对催化性能的影响 ,结果表明以SBA 15为载体的催化剂的性能好于MCM 41和Cab O Sil为载体的催化剂 ;与V2 O5,VO(C2 O4)相比 ,NH4VO3是制备性能良好的VOx/SBA 15的钒源 ;在VOx/SBA 15中 ,添加少量P元素后 ,HCHO的选择性有一定程度的提高 .XRD ,N2 物理吸附、UV Raman和H2 TPR表征结果表明 ,负载量低于 3wt%时 ,钒组分可能主要以高分散的单核的VOx 物种存在 ,我们推测该物种对甲烷选择氧化制甲醛起关键作用 .

低碳烷烃选择氧化反应中催化剂动态结构研究进展

考察低碳烷烃选择氧化反应中氧化物催化剂的动态结构 ,对于准确揭示反应条件下催化剂的构 效关系 ,设计高效催化剂具有重要意义。本文综述了近年来低碳烷烃选择氧化反应中氧化物催化剂动态结构的研究进展。

高分散隔离活性位催化剂在低碳烃选择氧化反应中的作用

阐述了低含量(活性位:载体原子分数f≤0.5%)、高分散隔离活性位催化剂在低碳烃尤其是甲烷、乙烷和丙烷等选择氧化生成含氧化合物和烯烃环氧化反应中的作用.对高分散隔离活性位催化剂活性物种的可能结构,高分散隔离活性物种对催化剂性能的影响等方面做了介绍;总结了其特殊的物化性质及作用机理.同时对该类催化剂的制备、表征及其在低碳烃其他反应中的应用作了简要说明.

纳米Co3O4的制备及其在富氢气氛下CO选择氧化反应中的催化性能

过渡金属氧化物四氧化三钴（Co3O4）在CO氧化反应中展示了较好的低温活性．Co3O4催化剂用于富氢气氛下CO选择氧化反应已引起了人们极大的关注。具有潜在的应用前景．采用液相沉淀一热解氧化方法制备了2种不同形貌的纳米Co3O4用X射线衍射（XRD）、扫描电子显微镜（SEM）等技术考察了包括沉淀剂种类、老化时间、焙烧温度等合成条件对生成Co3O4形貌、晶粒尺度的影响．制备的Co3O4的外形与沉淀前驱物外形直接相关．焙烧温度越高，Co3O4的颗粒越大．研究了制得的Co3O4在富氢气氛下C0选择氧化反应中的催化性能．对比以上方法制各的Co3O4的催化性能发现，催化剂的粒径和比表面积与催化剂的活性存在关联．使用尿素沉淀法并经250-300℃空气热解氧化制得的Co3O4具有较好的催化活性．

烃类晶格氧非定态选择氧化

以VPO催化剂上丁烷选择氧化制顺酐为例 ,说明对于用可变价金属的复合氧化物作为催化剂、按氧化还原机理进行的一大类烃类选择氧化反应 ,采用将催化循环的不同步骤在时间或空间上分离实现的方法 ,有可能大幅度提高反应的选择性 ,既节约资源 ,又减少CO2 的排放。

第四周期过渡金属钨磷杂多酸盐催化过氧化氢氧化正己醇成正己醛

以Keggin型杂多酸盐 (Na5PW11Z(H2 O)O3 9,Z =Mn ,Fe ,Co,Ni,Cu ,Zn ,以下简称为PW11Z)为催化剂 ,过氧化氢为氧化剂 ,在水—正己醇两相体系中进行了正己醇到正己醛的选择氧化反应 .在此选择氧化反应中同时伴随着过氧化氢分解的竞争反应 ,两种反应间存在着明显的对应关系 .在 70℃时 ,生成正己醛的催化剂活性序列为PW11Co>PW11Fe≈PW11Ni≈PW11Mn >PW11Cu≈PW11Zn ,其中PW11Co的正己醛收率为 3.3% ,当把过氧化氢稀释 ,向反应体系中滴入时 ,则正己醛的收率将大幅度提高 .对于PW11Co来说 ,正己醛的收率提高为 7.12 % ,选择性为 89.4% .还利用ICP ,IR 。

可在无添加剂情况下将苯乙烯氧化的微小的金团簇

一项新的研究结果表明，金纳米粒子的直径可以减小到1．4nm，它们能在无支撑材料或不加添加剂的条件下催化选择氧化反应。

一种多孔的有机小分子催化剂合成及性能表征

针对传统光催化剂在可见光区域光捕获能力差、光催化效果不佳的问题,提出一种新型的光催化剂,并通过苯甲醇的选择性氧化反应对光催化剂的活性进行表征。实验结果表明,在光催化剂用量为50mg、溶剂为正己烷、Cs_(2)CO_(3)用量为1.6mmol的条件下,苯甲醇反应转化率达54.8%,选择性为99%;经多次循环后,本实验制备的光催化剂催化的苯甲醇转化率仍维持在47%左右,表现出良好的催化活性和催化循环稳定性。对光催化剂的催化机理进行分析,活性基团·OH、·O_(2)^(-)、e-和h+均在转化反应中发挥重要的催化作用,CBO/WO_(3)复合催化剂中,在CBO导带中的电子和WO_(3)价带中的空穴作用下,使得O_(2)形成·O_(2)^(-)、H_(2)O形成·OH,因此,复合催化剂可以提供更多的活性物种,促进反应的进行,提升反映效率。

中国科学院大连化学物理研究所注重研发新型催化材料

中国科学院大连化学物理研究所（简称大化所）开发的“烃类选择氧化制对苯二甲酸产业化关键技术”通过了由中国科学院高技术研究与发展局组织的验收。据悉，其开发的非金属类催化新材料应用于烃类选择氧化反应，不仅实现了温和条件下的高选择氧化，而且还将氧化过程从传统的金属催化剂中解放出来。大化所设计开发的烃类选择氧化非金属催化新材料用于甲苯选择氧化制苯甲酸过程，转化率为20．9％，选择性98％以上，副产物较少，且催化剂用量少，反应运行平稳，不堵管，不结焦，不仅可大幅度提高装置产能，而且可显著降低物耗和成本。

Oxidative Dehydrogenation of Alkanes using Oxygen-Permeable Membrane Reactor

The oxidative dehydrogenation （ODH） reactions of ethane and propane were investigated in a catalytic membrane reactor, incorporating oxygen-permeable membranes based upon La2Ni0.9V0.1O4＋δor Ba0.5Sr0.5Co0.8Fe0.2O3-δ. As a compromise between the occurrence of a measureable oxygen flux and excessive homogenous gas phase reactions, the measurements were conducted at an intermediate temperature, either at 550 or 650 oC. The results show the dominating role of the oxygen flux across the membrane and available sites at the membrane surface in primary activation of the alkane and, hence, in achieving high alkane conversions. The experimental data of ODH of propane and ethane on both membrane materials can be reconciled on the basis of Mars-van Krevelen mechanism, in which the alkane reacts with lattice oxygen on the membrane surface to produce the corresponding olefin. It is further demonstrated that the oxygen concentration in the gas phase and on the membrane surface is crucial for determining the olefin selectivity.

杂多化合物催化剂及其制备方法和应用

本发明涉及杂多化合物催化剂及其制备方法和用于丙烯一步选择氧化生产丙烯酸的方法，杂多化合物催化剂由磷钼系杂多化合物和载体组成，所述磷钼系杂多化合物的通式为：PMoaVbTecAsdMe^1Mf^2Ox，所述催化剂用于丙烯一步选择氧化生产丙烯酸的方法包括丙烯和氧气或空气、氮气的原料气混合物在杂多化合物催化剂作用下进行选择氧化反应；本发明简化了流程，节省了投资，降低了生产费用，使取代两步生产丙烯酸的方法成为可能。

Solvent-free selective oxidation of cyclohexane with molecular oxygen over manganese oxides:Effect of the calcination temperature

The effects of calcination temperature on the physicochemical properties of manganese oxide catalysts prepared by a precipitation method were assessed by X-ray diffraction,N2 adsorption-desorption,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,O2 temperature-programmed desorption,and thermogravimetry-differential analysis.The catalytic performance of each of these materials during the selective oxidation of cyclohexane with oxygen in a solvent-free system was subsequently examined.It was found that the MnOx-500 catalyst,calcined at 500 °C,consisted of a Mn2O3 phase in addition to Mn5O8 and Mn3O4 phases and possessed a low surface area.Unlike MnOx-500,the MnOx-400 catalyst prepared at 400 °C was composed solely of Mn3O4 and Mn5O8 and had a higher surface area.The pronounced catalytic activity of this latter material for the oxidation of cyclohexene was determined to result from numerous factors,including a higher concentration of surface adsorbed oxygen,greater quantities of the surface Mn4＋ ions that promote oxygen mobility and the extent of O2 adsorption and reducibility on the catalyst.The effects of various reaction conditions on the activity of the MnOx-400 during the oxidation of cyclohexane were also evaluated,such as the reaction temperature,reaction time,and initial oxygen pressure.Following a 4 h reaction at an initial O2 pressure of 0.5 MPa and 140 °C,an 8.0% cyclohexane conversion and 5.0% yield of cyclohexanol and cyclohexanone were achieved over the MnOx-400 catalyst.In contrast,employing MnOx-500 resulted in a 6.1% conversion of cyclohexane and 75% selectivity for cyclohexanol and cyclohexanone.After being recycled through 10 replicate uses,the catalytic activity of the MnOx-400 catalyst was unchanged,demonstrating its good stability.

Kinetic Model and Simulation of Promoted Selective Non-catalytic Reduction by Sodium Carbonate

Abstract The detailed kinetic model of selective non-catalytic reduction （SNCR） of nitric oxide, including so-dium species reactions, was deyeloped on the basis of recent studies on thermal DeNOx mechanism, NOxOUTmechanism and promotion mechanism of Na2CO3. The model was validated by comparison with several experi-mental findings, thus providing an effective tool for the primary and promoted SNCR process simulation. Experimental and simulated results show part-per-million level of sodium carbonate enhances NO removal efficiency andextend the effective SNCR temperature range in comparison with use of a nitrogen agent alone. The kinetic modeling, sensitivity and rate-of-production analysis suggest that the performance improvement can be explained as ho-mogeneous sodium species reactions producing more reactive OH radicals. The net result of sodium species reac-tions is conversion of H2O and inactive HO2 radicals into reactive OH radicals, i.e. H2O＋HO2=3OH, which enhances the SNCR performance of nitrogen agents by mainly increasing the production rate of NH2 radicals. More-over, N2O and CO are eliminated diversely via the reactions Na＋N20=NaO＋N2, NaO＋CO=Na＋CO2 andNaO2＋CO =NaO＋CO2, in.the pro.moted SNCR process, especially in the NOxOUT process.

Robust cobalt oxide catalysts for controllable hydrogenation of carboxylic acids to alcohols

The selective catalytic hydrogenation of carboxylic acids is an important process for alcohol production,while efficient heterogeneous catalyst systems are still being explored.Here,we report the selective hydrogenation of carboxylic acids using earth‐abundant cobalt oxides through a reaction‐controlled catalysis process.The further reaction of the alcohols is completely hindered by the presence of carboxylic acids in the reaction system.The partial reduction of cobalt oxides by hydrogen at designated temperatures can dramatically enhance the catalytic activity of pristine samples.A wide range of carboxylic acids with a variety of functional groups can be converted to the corresponding alcohols at a yield level applicable to large‐scale production.Cobalt monoxide was established as the preferred active phase for the selective hydrogenation of carboxylic acids.

Preparation of Vitamin E Intermediate from an Inexpensive Substrate by Selective Oxidation of Pseudocumene in HCOOH–H_2O_2 System

In this paper, 2,3,5-trimethyl-1,4-benzoquinone（TMBQ） was synthesized through the direct oxidation of1,2,4-trimethylbenzene（pseudocumene, TMB） in the HCOOH–H2O2 system. The influence ofthree active species was studied, including performic acid（PFA） generated in formic acid, peracetic acid（PAA） generated in acetic acid, and trifluoroperacetic（TFPA） acid generated in trifluoroacetic acid. The effects ofsulfuric acid and sodium formate addition were investigated, the overoxidation ofTMB was discussed, and the main reason for the decreasing selectivity was revealed. The oxidation ofTMB can be controlled and improved through adjusting the reaction temperature, mole ratio ofoxidant to substrate, and reactant concentration. The TMBQ yield of28% was achieved with a TMB concentration of0.2 mol/L, H2O2/TMB mole ratio of6：1, and reaction temperature 37 ℃. The selectivity of72% was obtained with a TMB concentration of0.2 mol/L, H2O2/TMB mole ratio of5：1, and reaction temperature of27 ℃. The reaction mechanisms were proposed and discussed based on the gas chromatography–flame ionization detection（GC–FID） and gas chromatography–mass spectrometer（GC–MS） results.

Importance, features and uses of metal oxide catalysts in heterogeneous catalysis

This short review paper aims at assembling the present state of the art of the multiuses of metal oxides in heterogeneous catalysis, concerning liquid and gaseous phases of the reactant mixtures on solid catalysts. It includes the description of the main types of metal oxide catalysts, of their various preparation procedures and of the main reactions catalysed by them (acid-base type, selective and total oxidations, bi-functional catalysis, photocatalysis, biomass treatments, environmental catalysis and some of the numerous industrial applications). Challenges and prospectives are also discussed.

Ru/FeO_x catalyst performance design: Highly dispersed Ru species for selective carbon dioxide hydrogenation

A series of Ru/FeOx catalysts were synthesized for the selective hydrogenation of CO2to CO.Detailed characterizations of the catalysts through X‐ray diffraction,X‐ray photoelectron spectroscopy,transmission electron microscopy,and temperature‐programmed techniques were performed to directly monitor the surface chemical properties and the catalytic performance to elucidate the reaction mechanism.Highly dispersed Ru species were observed on the surface of FeOx regardless of the initial Ru loading.Varying the Ru loading resulted in changes to the Ru coverage over the FeOx surface,which had a significant impact on the interaction between Ru and adsorbed H,and concomitantly,the H2activation capacity via the ability for H2dissociation.FeOx having0.01%of Ru loading exhibited100%selectivity toward CO resulting from the very strong interaction between Ru and adsorbed H,which limits the desorption of the activated H species and hinders over‐reduction of CO to CH4.Further increasing the Ru loading of the catalysts to above0.01%resulted in the adsorbed H to be easily dissociated,as a result of a weaker interaction with Ru,which allowed excessive CO reduction to produce CH4.Understanding how to selectively design the catalyst by tuning the initial loading of the active phase has broader implications on the design of supported metal catalysts toward preparing liquid fuels from CO2.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences toward preparing liquid fuels from CO2.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Selective Se doping of NiFe_(2)O_(4) on an active NiOOH scaffold for efficient and robust water oxidation

There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,an etching-assisted synthesis approach was developed to integrate highly active NiFe2O4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel.A precise selenization strategy was then introduced to achieve selective Se doping of NiFe2O4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution.The resulting NiFe2O4-xSex/NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm^(−2),respectively.More importantly,the catalyst exhibited remarkable durability at a stable current output of 100 mA cm^(−2)for hundreds of hours.These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials.