有序介孔碳载钯的制备、表征及对甲酸的电催化氧化性能

通过浸渍法和硫引入贵金属法分别制备了主要负载在介孔碳主孔道(MPC/Pd-1)和负载在介孔碳孔壁上小介孔中[MPC/(S)Pd-2]的两类负载型钯电催化剂, 用XRD, SEM, TEM和电化学等方法表征了其结构和电催化性能. 循环伏安结果表明, 有序介孔碳载钯催化剂MPC/Pd-1和MPC/(S)Pd-2对甲酸氧化的催化活性分别是商用钯黑催化剂的4.0和2.4倍. MPC/Pd-1中的钯位于介孔碳的主孔道上, 增加了催化剂/电解质/反应物三相界面的面积, 使得其比MPC/(S)Pd-2的催化活性更高.     

纳米限域体系内聚对苯撑乙烯的合成

将钯催化剂负载在介孔硅材料的纳米孔道中，从而将催化的Heck偶联聚合反应引导至纳米限域反应体系，利用纳米孔道的空间限域效应实现了对所合成的聚对苯撑乙烯（PPV）分子量的控制。在6种钯纳米反应器中催化己氧基取代二碘苯单体与二乙烯基苯单体的Heck偶联聚合反应，通过红外光谱确定聚合物主链为对位苯环和乙烯基交替的结构。由凝胶渗透色谱对所获得的PPV的分子量进行表征，证明钯纳米反应器催化体系催化聚合反应所得PPV的分子量分布均较均相催化体系更窄，PPV的多分散指数最低可达1.53。     

Pd/PdO在MCM-41介孔材料孔表面的溶液移植

利用PdCl~2溶液与介孔结构硅酸铝合成原粉反应,把Pd/PdO多用途催化剂移植到MCM-41材料孔表面。产物用XRD,热分析(TG/DTA),TEM,N~2吸附及FT-IR光谱等手段进行表征。结果表明,钯经由Si-O-Pd键负载在硅酸铝骨架及孔表面上。在有序介孔材料外表面沿着孔道方向粘附着直径为10-30nm的Pd/PdO晶粒。研究表明,采用这种液相移植的方法可以有效负载金属催化剂,并防止孔道堵塞。     

有序多孔过渡金属氧化物及其负载贵金属催化剂对挥发性有机物氧化的催化性能

大部分的挥发性有机物(VOCs)污染环境,危害人身健康.目前,我国虽然已开展了治理 VOCs污染的工作,但还缺乏有效的、拥有自主知识产权的 VOCs治理技术,因此研发新型高效 VOCs处理技术迫在眉睫.催化氧化法是公认的最有效消除 VOCs的途径之一,而高性能催化剂的研发是实现该过程的关键.近年来,人们围绕消除 VOCs的高效且价廉的催化剂的研发开展了卓有成效的工作,许多过渡金属氧化物、混合或复合金属氧化物及其负载贵金属催化剂均被认为是有效的催化氧化材料.与体相材料相比,多孔材料具有发达的孔道结构和高的比表面积,一方面有利于反应物的扩散、吸附和脱附,因而具有更高的催化活性和选择性;另一方面有利于活性组分(如贵金属等)在多孔材料表面的高分散,抑制活性组分的烧结,因而具有更好的催化稳定性.本文简述了近年来多孔金属氧化物在环境污染物消除领域的研究进展,阐述了以有序介孔或大孔过渡金属氧化物、钙钛矿型氧化物和负载贵金属催化剂的制备及其对典型 VOCs(如苯系物、醇类、醛类及酮类等)氧化的催化性能,重点介绍了四类催化材料,包括有序介孔过渡金属氧化物或复合氧化物(Co3O4, MnO2, Fe2O3, Cr2O3和 LaFeO3等)催化剂,有序介孔金属氧化物负载贵金属(Au/Co3O4, Au/MnO2和 Pd/Co3O4等)催化剂,三维有序大孔过渡金属氧化物或复合氧化物(Fe2O3, LaMnO3, La0.6Sr0.4MnO3和 La2CuO4等)催化剂,以及三维有序大孔金属氧化物负载贵金属(Au/Co3O4, Au/LaCoO3, Au/La0.6Sr0.4MnO3和 AuPd/Co3O4等)催化剂的制备及其物化性质与对苯、甲苯、二甲苯、乙醇、丙酮、甲醛、甲烷或氯甲烷等 VOCs氧化的催化性能之间的相关性.借助二氧化硅或聚甲基丙烯酸甲酯微球等硬模板,采用纳米浇铸法可制备出二维或三维的有序单一或多级孔道结构的金属氧化物.研究表明,多孔金属氧化物的催化性能远优于其体相甚至纳米催化剂的.有序多孔材料的优异催化性能与其拥有大的比表面积、高的吸附氧物种浓度、优良的低温还原性、独特的孔道结构、活性组分的高分散以及贵金属与氧化物载体之间的强相互作用等有关.探明影响催化剂活性的因素有利于从原子水平上认识催化过程,为新型高效催化剂的设计与制备奠定基础.本文还指出了此类研究中存在的一些问题,例如利用硬模板法制备多孔材料的缺点是目标催化剂的收率低,硬模板浪费严重,大规模制备多孔催化剂势必增加制备成本,这些问题有待于妥善解决.与此同时,还展望了 VOCs消除技术的未来发展趋势,采用多种技术联用的方法有望最大程度地提高 VOCs的消除效率.     

有序多孔过渡金属氧化物及其负载贵金属催化剂对挥发性有机物氧化的催化性能（英文）

大部分的挥发性有机物(VOCs)污染环境,危害人身健康.目前,我国虽然已开展了治理VOCs污染的工作,但还缺乏有效的、拥有自主知识产权的VOCs治理技术,因此研发新型高效VOCs处理技术迫在眉睫.催化氧化法是公认的最有效消除VOCs的途径之一,而高性能催化剂的研发是实现该过程的关键.近年来,人们围绕消除VOCs的高效且价廉的催化剂的研发开展了卓有成效的工作,许多过渡金属氧化物、混合或复合金属氧化物及其负载贵金属催化剂均被认为是有效的催化氧化材料.与体相材料相比,多孔材料具有发达的孔道结构和高的比表面积,一方面有利于反应物的扩散、吸附和脱附,因而具有更高的催化活性和选择性;另一方面有利于活性组分(如贵金属等)在多孔材料表面的高分散,抑制活性组分的烧结,因而具有更好的催化稳定性.本文简述了近年来多孔金属氧化物在环境污染物消除领域的研究进展,阐述了以有序介孔或大孔过渡金属氧化物、钙钛矿型氧化物和负载贵金属催化剂的制备及其对典型VOCs(如苯系物、醇类、醛类及酮类等)氧化的催化性能,重点介绍了四类催化材料,包括有序介孔过渡金属氧化物或复合氧化物(Co_3O_4,MnO_2,Fe_2O_3,Cr_2O_3和LaFeO_3等)催化剂,有序介孔金属氧化物负载贵金属(Au/Co_3O_4,Au/MnO_2和Pd/Co_3O_4等)催化剂,三维有序大孔过渡金属氧化物或复合氧化物(Fe_2O_3,LaMnO_3,La_(0.6)Sr_(0.4)MnO_3和La_2CuO_4等)催化剂,以及三维有序大孔金属氧化物负载贵金属(Au/Co_3O_4,Au/LaCoO_3,Au/La_(0.6)Sr_(0.4)MnO_3和AuPd/Co_3O_4等)催化剂的制备及其物化性质与对苯、甲苯、二甲苯、乙醇、丙酮、甲醛、甲烷或氯甲烷等VOCs氧化的催化性能之间的相关性.借助二氧化硅或聚甲基丙烯酸甲酯微球等硬模板,采用纳米浇铸法可制备出二维或三维的有序单一或多级孔道结构的金属氧化物.研究表明,多孔金属氧化物的催化性能远优于其体相甚至纳米催化剂的.有序多孔材料的优异催化性能与其拥有大的比表面积、高的吸附氧物种浓度、优良的低温还原性、独特的孔道结构、活性组分的高分散以及贵金属与氧化物载体之间的强相互作用等有关.探明影响催化剂活性的因素有利于从原子水平上认识催化过程,为新型高效催化剂的设计与制备奠定基础.本文还指出了此类研究中存在的一些问题,例如利用硬模板法制备多孔材料的缺点是目标催化剂的收率低,硬模板浪费严重,大规模制备多孔催化剂势必增加制备成本,这些问题有待于妥善解决.与此同时,还展望了VOCs消除技术的未来发展趋势,采用多种技术联用的方法有望最大程度地提高VOCs的消除效率.     

淀粉负载钯催化剂的制备及对Heck反应的催化性能

淀粉负载钯催化剂的制备及对Heck反应的催化性能;淀粉;钯;负载型催化剂;Heck反应     

介孔γ-Al2O3微球的高效制备及负载Pd催化剂的性能

多孔γ-Al₂O₃由于具有高比表面积、 强吸附性和良好的热稳定性而被广泛用作载体材料. 但其存在制备方法复杂、 能耗高、 纯度低及环境污染等问题, 因此开发高效制备高纯度多孔γ-Al₂O₃的合成方法具有重要的研究价值. 本文利用醇铝水解缩合反应, 在常温常压下一步合成出具有高比表面积、 高孔体积、 高纯度的介孔纳米片状γ-Al₂O₃微球, 研究了醇铝水解缩合反应过程中添加剂用量、 反应温度和后处理烘干温度等条件对γ-Al₂O₃孔道结构及形貌的影响. 并采用浸渍法进一步制备出贵金属Pd高度分散的负载型介孔Pd/γ-Al₂O₃微球催化材料, 其在硝基苯加氢和苯甲醇氧化反应中均表现出优异的催化性能. 由于丰富的介孔孔道结构和高度分散的负载贵金属Pd, 介孔Pd/γ-Al₂O₃微球在反应30 min后就达到了93.78%的硝基苯转化率和98.58%的苯胺选择性, 比商用的纳米颗粒型Pd/γ-Al₂O₃分别提高了15.55%和17.58%, 且循环使用后其催化性能基本保持不变. 在苯甲醇氧化反应中, 介孔Pd/γ-Al₂O₃微球的苯甲醇转化率较对比样提高了26.39%且长时间保持不变. 本工作为开发高性能多孔γ-Al₂O₃负载型催化材料提供新的思路.     

In This Issue

正封面:面向能源、环境、绿色化工等领域的广泛需求,近年来多种新型多孔材料问世,其中介孔材料、杂化多孔固体如金属有机骨架结构等具有有序孔道结构的催化材料得到蓬勃发展,本期"新型多孔催化材料"专栏,封面选载了3篇报道,分别为可高效催化甲醇电催化氧化且抗CO中毒的介孔碳负载PtRu等合金催化剂、低温氧化甲醛的三维有序介孔MnO_2材料、具有优异硝基苯催化加氢活性的MIL-101负载NiPd核壳纳米催化剂.     

Nafion功能化介孔催化剂上苯甲醚/苯甲酰氯酰基化反应研究

苯甲醚/苯甲酰氯的酰基化产物4-甲氧基二苯甲酮是多种精细化工产品的重要中间体. 本工作主要介绍了Nafion负载型SBA-15, SBA-16及Me-SBA-15介孔超强酸催化剂的制备及其在苯甲醚/苯甲酰氯酰基化反应中的应用. 实验结果表明, 单位时间单位Nafion活性位上的苯甲酰氯转化数高于传统HBeta沸石和硫酸氧化锆, 且载量的增加能显著提高酰基化催化性能. 甲基修饰的Me-SBA-15介孔材料明显改善了催化剂表面的疏水性能, 有效减缓了多聚芳烃副产物的生成, 反应的转化率得到大幅提高. 相对一维孔道结构的介孔SBA-15而言, 三维笼状结构的SBA-16对反应物及产物分子具有更好的扩散性能, 该结构优势由酰基化反应的高初始活性得以充分体现. 在整个反应过程中, 该类催化剂对4-甲氧基二苯甲酮具有专一的选择性.     

Pt/Co_3O_4/3DOM Al_2O_3:甲苯燃烧的高效催化剂（英文）

与硫氧化物、氮氧化物、一氧化碳以及悬浮颗粒一样,大部分挥发性有机物(VOCs)污染大气环境.控制VOCs排放有多种方法,其中催化氧化法是一种有效技术,关键在于获得高效催化剂.近年来,负载过渡金属和贵金属催化剂因具有比单纯负载贵金属和单纯负载过渡金属氧化物更好的催化性能而备受关注.在负载贵金属催化剂中,高比表面积载体负载Pt,Pd或Rh催化剂得到广泛而深入的研究,尽管这些催化剂成本较高,但是其对VOCs氧化反应显示了很高的低温催化活性.众所周知,催化活性取决于贵金属和VOCs的种类,不同负载贵金属催化剂对特定反应会表现出不同的催化活性.负载Pt催化剂对长链碳氢化合物和芳香族化合物氧化反应表现出更高的活性.相对于负载贵金属催化剂,负载过渡金属氧化物催化剂不仅具有良好的氧化活性,而且价格低廉.迄今已发现许多过渡金属氧化物(如Co_3O_4,Cr_2O_3和MnO_2等)对典型VOCs氧化反应具有催化活性,其中Co_3O_4的催化活性尤为突出.研究表明,Co_3O_4的性质和分散度是决定其性能的关键因素,制备方法、载体性质和过渡金属氧化物负载量对Co_3O_4的物化性质具有重要影响,而且在负载Pt催化剂中添加金属氧化物能改善其催化性能.尽管多孔氧化铝是一种常用的载体材料,但目前尚无文献报道三维有序大孔-介孔氧化铝负载Co_3O_4和Pt纳米粒子催化剂的制备及其对甲苯氧化反应的催化性能.本文采用聚甲基丙烯酸甲酯微球胶晶模板法、等体积浸渍法和聚乙烯醇保护的硼氢化钠还原法制备了三维有序大孔-介孔(3DOM Al_2O_3)负载Co_3O_4和Pt(xP t/yCo_3O_4/3DOM Al_2O_3,Pt的质量分数(x%)为0-1.4%,Co_3O_4的质量分数(y%)为0-9.2%)纳米催化剂.通过电感耦合等离子体原子发射光谱、X射线衍射、氮气吸附-脱附、扫描电子显微镜、透射电子显微镜、选区电子衍射、X射线光电子能谱及氢气程序升温还原等技术表征了催化剂的物化性质,利用固定床微型石英反应器评价了催化剂对甲苯氧化反应的催化活性.结果表明,xP t/yC o3O4/3DOM Al_2O_3催化剂具有多级孔结构(大孔孔径为180–200 nm,介孔孔径为4–6 nm),比表面积为94-102 m2/g.粒径为18.3 nm的Co_3O_4纳米粒子和粒径为2.3-2.5 nm的Pt纳米粒子均匀分散在3DOM Al_2O_3表面.在xP t/y Co_3O_4/3DOM Al_2O_3催化剂中,1.3Pt/8.9Co_3O_4/3DOM Al_2O_3拥有最高的Oads浓度、最好的低温还原性和最高的甲苯氧化反应催化活性(当空速为20000 mL g~(-1) h~(-1)时,甲苯转化率达90%的反应温度为160 oC).基于催化剂的活性数据和结构表征,我们认为,1.3Pt/8.9Co_3O_4/3DOM Al_2O_3优异的催化性能与其高分散的Pt纳米粒子、高的Oads浓度、好的低温还原性、Pt和Co_3O_4纳米粒子间的强相互作用以及多级孔结构相关.     

钇掺杂介孔氧化锆材料的合成与表征

近年来一种新型纳米结构材料-介孔材料引起越来越广泛的兴趣。作者利用表 面活性剂辅助模板及后处理工艺成功实现了过渡金属钇在有序介孔氧化锆骨架中的 掺杂改性。借助XRD，TEM，EDS和荧光光谱以及紫外-可见吸收等分析手段进行样品 结构及性能表征。研究结果表明，金属钇离子能均匀地掺杂于规则的介孔氧化锆骨 架中。掺杂改性后的介孔氧化锆试样经激发后室温下呈现特殊的荧光（蓝光）发射 现象，并认为这种荧光响应与钇掺杂氧化锆产生氧空位缺陷有关。     

Deaminative (Carbonylative) Alkyl‐Heck‐type Reactions Enabled by Photocatalytic C−N Bond Activation

The palladium‐catalyzed Heck reaction is a well‐known, Nobel Prize winning transformation for producing alkenes. Unlike the alkenyl and aryl variants of the Heck reaction, the alkyl‐Heck reaction is still underdeveloped owing to the competitive side reactions of alkyl–palladium species. Herein, we describe the development of a deaminative alkyl‐Heck‐type reaction that proceeds through C?N bond activation by visible‐light photoredox catalysis. A variety of aliphatic primary amines were found to be efficient starting materials for this new process, affording the corresponding alkene products in good yields under mild reaction conditions. Moreover, this strategy was successfully applied to deaminative carbonylative alkyl‐Heck‐type reactions.     

Heck reactions with various types of palladium complex catalysts: application of multiphase catalysis and supercritical carbon dioxide

The application of multiphase catalytic systems for palladium catalyzed Heck reactions brings several benefits such as easy catalyst-product separation and catalyst recycling. The effective multiphase Heck systems can be prepared by using different types of catalyst phases, including biphasic catalysis and supported liquid phase catalysts, and a new generation solvent of supercritical carbon dioxide.     

In situ formation of dispersed palladium nanoparticles in microemulsion: efficient reaction system for ligand-free Heck reaction

The ligand-free Heck reaction catalyzed by Pd(OAc)2 performed well in a TX10 oil-in-water microemulsion. TEM proved in situ formation distributed palladium nanoparticles in the microemulsion. The role of TX10 in the reaction system is the palladium nanoparticles reducing agent and stabilizer. The effect of reaction parameters on the Heck reaction conversion were discussed. The results indicated that the aqueous phase concentration, the base concentration, and the temperature played key roles in the conversion of the reaction. Iodobenzene was converted to the corresponding trans-stilbene quantitatively within 90-150 min. Therefore, the heptane/TX 10/butanol/water/propylene glycol microemulsion containing in situ formed palladium nanoparticles was a very efficient catalyst system for the ligand-free Heck reaction.     

Preparation of a PEG‐Supported Ligand as Highly Stable Palladium Catalyst and Its Efficient Recyclability in the Heck Reaction

A reagent of NNN ligands immobilized on PEG has been prepared and coordinated to Pd(OAc)₂ to provide a highly efficient and recyclable catalysis system for the Heck reaction. The reaction works very well with this catalysis system, and no palladium black is observed during the reaction. The reagent and palladium can be recycled easily and do not show significant activity decay after being reused 10 times.     

无电沉积高密度钯金属纳米线阵列

利用介孔氧化硅薄膜作为模板,通过无电沉积路线在介孔薄膜孔道内合成了高密度钯金属纳米线阵列.利用介孔薄膜导向剂的疏水区作为载体,引进钯金属疏水化合物并经热解和还原,得到钯微粒,以此为催化中心引发无电沉积,避免了传统无电沉积复杂的工艺过程.结果表明,纳米线尺寸均一,长径比大于60,完全填充了介孔薄膜的孔道,并可通过介孔模板孔径的选择对纳米线直径加以调控.     

Anilide activation of adjacent C-H bonds in the palladium-catalysed Fujiwara-Moritani reaction

The Pd(II)-catalysed oxidative counterpart of the Heck reaction, originally described by Fujiwara and Moritani, has been studied in detail by a combination of NMR, single-crystal X-ray diffraction and substrate variation. The process involves a palladacycle that is a true intermediate in catalysis. Pd(OAc)(2) is first converted into a more electrophilic palladium species for effective catalysis, defining the main role of added acid. In the course of these studies, three palladacyclic intermediates have been characterised by X-ray diffraction, firstly the directly produced acetate complex 1, the camphorsulfonate complex 2, and additionally tosylate 3, isolated from a reacting system, demonstrating the accessibility of a cationic or comparably electrophilic palladium entity under turnover conditions. The isolated palladacycle 3 is also an effective catalyst. The reaction rate shows a first-order dependency on [anilide] and [Pd], but not on benzoquinone, alkene or p-TsOH. Acid, in the form of p-TsOH, is an essential component, whereas acetate is dispensable. A crossover experiment involving distinct substitution in reactant and palladacycle demonstrates that the palladacycle is directly involved in the catalysis.     

Bimetallic nickel and palladium complexes for catalytic applications

South Africa is a mineral-rich country and one area in which minerals can be very important is catalysis. Over an extended period of time, homogeneous catalysis has grown to become very useful, particularly in the chemical and pharmaceutical industries. The organometallic compounds required in the catalysis industry have advanced from metallocenes to an alternative in the form of a-diimines. Most a-diimines are prepared from iminopyridyl moieties and are most active with nickel and palladium transition metals. This review providesa history of homogeneous catalysis and a discussion on iminopyridines, with the main focus on the nickel and palladium complexes formed from them. There follows a discussion of the bimetallic nickel and palladium complexes in various catalytic applications such as Suzuki and Heck coupling, with the main focus on ethylene polymerisation. The limitations are addressed and possible solutions presented to overcome those challenges. Several reviews in the related topics are to be found in the literature but not the a-diimine with iminopyridines and bimetallic nickel and palladium metals.     

Immobilization of palladium in mesoporous silica matrix: preparation, characterization, and its catalytic efficacy in carbon-carbon coupling reactions

Palladium(0) has been immobilized into the silica-based mesoporous material to develop catalyst Pd(0)-MCM-41, which is found to be highly active in carbon-carbon coupling reactions. [Pd(NH3)4]2+ ions have been incorporated into the mesoporous material during synthesis of MCM-41 and subsequently upon treatments with hydrazine hydrate Pd2+ ions present in mesoporous silica matrix were reduced to Pd(0) almost instantaneously. The catalyst has been characterized by small-angle X-ray diffraction, N2 sorption, and transmission electron microscopy (TEM). TEM and surface area measurements clearly demonstrate that the immobilization of Pd(0) into the mesoporous silica has a significant effect on pore structure of the catalyst. Nevertheless, after immobilization of palladium the meso-porosity of the material is retained, as evidenced in the nitrogen sorption measurement. The TEM micrograph shows that both MCM-41 and Pd(0)-MCM-41 have similar types of external surface morphology; however, Pd(0)-MCM-41 was less ordered. Pd(0)-MCM-41 showed high catalytic activity toward carbon-carbon bond formation reactions like Heck and Sonogashira coupling, as evidenced in high turn-over numbers. In contrast to many other Pd-based catalysts reported so far, Pd(0)-MCM-41 acts as a truly heterogeneous catalyst in C-C coupling reactions. Notably, the new heterogeneous catalyst is found to be efficient in the activation of arylchloride to give impressive conversion in cross coupling (15-45% for Heck and 30% for Sonogashira) reactions under mild conditions.     

Ordered mesoporous SBA‐15/PrSO3Pd and SBA‐15/PrSO3PdNP as active,reusable and selective phosphine‐free catalysts in CX activation Heck coupling process

The incorporation of sulfonate into mesoporous SBA‐15 molecular sieves as ligands for palladium ions was used. Then SBA‐15/PrSO₃Pd and SBA‐15/PrSO₃Pd_NP were prepared and applied for the Heck arylation reaction of conjugate alkenes with aryl halides, to afford corresponding cross‐coupling products under phosphine‐free aerobic conditions with good to excellent yields. These supported palladium pre‐catalysts could be separated easily from reaction products and reused several times, showing superiority over homogeneous catalysts for industrial and chemical applications. Copyright © 2015 John Wiley & Sons, Ltd.