TiO2·Al2O3复合氧化物载体研究进展

TiO2.Al2O3多孔复合氧化物是新型的催化剂载体材料,因其在加氢精制工艺上能够显著增加催化剂的脱硫、脱氮活性而逐渐受到重视。本文综述了国内外关于TiO2·Al2O3多孔材料的制备方法,分析了制备方法对材料的比表面积、孔结构、表面酸性等载体性能影响的一般规律。通过对国内外研究者的TiO2·Al2O3合成方法的综合评述...     

CeO2的制备及其在催化剂载体中的应用研究进展

概述了 CeO₂的制备方法对其性能的影响以及CeO2在催化剂载体中的运用,指出 CeO₂独特的储放氧性能使其在氧化反应、甲醇裂解、重整及变换反应和氮氧化物的还原等反应过程中呈现了良好的载体功能;溶胶-凝胶法以及超临界干燥等方法可以制备大比表面积的载体 CeO₂。制约载体 CeO₂工业应用的因素在于其机械强度和耐热性。     

硅铝复合氧化物催化材料的研究进展

综述了硅铝复合氧化物的制备方法,主要介绍了溶胶-凝胶法、沉淀法、水热合成法、混合法和浸渍法及其优缺点。溶胶-凝胶法因其可以制得高比表面、大孔径、孔分布集中的硅铝复合氧化物材料被广泛采用。介绍了硅铝复合氧化物材料作为催化剂载体应用于工业生产的现状,及其存在的问题和今后的发展方向。     

纳米ZnO/CeO2复合氧化物的制备及其改性

以燃烧法制备氧化锌并以其为包裹对象用沉淀法合成ZnO/CeO₂复合氧化物,采用XRD、SEM 、IR、TG-DTA、UV-Vis、TEM对样品进行表征,结果表明氧化铈以包覆形式与氧化锌形成复合氧化物。用改性剂对复合氧化物进行改性研究,以亲油化度考察改性剂的类型、改性剂的用量、改性温度、pH值对改性效果的影响。实验结果表明:当选用硬脂酸钠为改性剂且用量为ZnO/CeO₂的4%,改性温度为60℃,pH值为7时,样品粒径明显变小,分散性变好,亲油化度明显提高,可获得最佳改性效果。     

TiO2复合氧化物的制备及其加氢脱硫应用进展

对TiO2及TiO2-Al2O3、TiO2-SiO2和TiO2-ZrO2载体的制备技术及其在加氢脱硫中的应用做了综述。众多研究者的研究表明，以TiO2调变的Al2O3、SiO2、ZrO2载体能影响MoO3与Al2O3、MoO3与SiO2及MoO3与ZrO2之间的相互作用，改善MoO3，在载体表面的分散，促进其还原，有利于提高催化剂表面活性组分的数量，提高催化剂的HDS活性。     

射频磁控溅射法制备PI基CeO2-TiO2复合薄膜

采用射频磁控溅射技术在柔性基体PI(聚酰亚胺)上制备了纳米CeO2-TiO2复合薄膜.借助X射线衍射(XRD)、原子力显微镜(AFM)和紫外-可见光谱仪分别研究了薄膜的物相结构、表面生长形貌和薄膜的紫外-可见光透过率及光学能隙,并用WS-2000型薄膜划痕仪测定薄膜与基体的界面结合强度.实验结果表明:沉积态的薄膜为非晶态,经200℃退火处理4h后,转化为良好的晶态,薄膜中主要含有锐钛矿相结构;溅射功率对薄膜的形貌,光学性能及界面结合力均有影响.尤其当溅射功率为120W时,薄膜的综合性能最优;平均晶粒尺寸110nm,表面粗糙度为160nm,吸光率达80%,光学能隙Eg仅为(2.65±0.05)eV,划痕法测量涂层与基体的附着力为60N.     

贵金属加氢脱芳催化剂的复合氧化物载体的研究进展

催化剂载体是加氢脱芳（HDA）研究的重要内容,20世纪80年代以来,复合载体受到了极大的关注。综述了近年来贵金属深度加氢脱芳催化剂载体（负载贵金属Pd和Pt）的研究进展。主要介绍了含Al2O3、TiO2及SiO2的复合氧化物载体的催化剂在芳烃加氢过程中表现出的加氢活性和抗硫性。无论从催化剂的催化活性,还是抗硫性能方面比较,复合氧化物载体的催化剂都表现出良好的性能,尤其是三元复合氧化物载体的催化剂,比其他更加稳定,具有更好的催化性能。     

TiO_2-SiO_2复合氧化物载体的pH值和焙烧温度对催化剂的辛烷异构化性能的影响

采用溶胶-凝胶法制备TiO_2-SiO_2复合氧化物载体,通过超声浸渍法制备Ni O和WO3改性负载的Ni O-WO3/TiO_2-SiO_2催化剂,考察不同p H值和焙烧温度条件下制备的载体对催化剂辛烷异构化性能的影响。结果表明,制备的Ni O-WO3/TiO_2-SiO_2催化剂呈多孔结构,平均孔径约5 nm,平均晶粒尺寸(10~20)nm。以焙烧温度500℃和p H=2条件下制备的TiO_2-SiO_2为载体,制得的催化剂比表面积达322.51 m2·g-1,在辛烷异构化反应中,正辛烷转化率为28.3%,选择性85.1%。     

负载型NiMo加氢处理催化剂氧化物载体研究进展

以NiMo在加氢精制中的应用为线索,按催化剂载体的不同,简介了以单一氧化物和复合氧化物为载体的催化剂的制备方法,总结了NiMo为活性组分,氧化物为载体的加氢精制催化剂的应用进展。按照载体的不同,从单一氧化物载体Al_2O_3,TiO_2和SiO_2,以及复合氧化物载体角度总结了催化剂在加氢精制中的应用。氧化物载体具有热稳定性好,酸碱性适宜的特点,一直是人们研究的重要内容。     

sol-gel法制备CeO2-TiO2/凹凸棒石复合材料的催化性能

以凹凸棒石(ATP)为载体,Ce(NO₃)₃·6H₂O和Ti(OBu)₄为原料,冰醋酸为抑制剂,采用溶胶-凝胶法制备CeO₂-TiO₂/ATP纳米复合材料。利用TG-DSC、TEM、XRD和N₂吸附/脱附仪对复合材料进行表征,考察铈钛摩尔比对所制备样品催化降解罗丹明B溶液性能的影响。结果表明,当Ce/Ti≥5/5时,具有立方萤石结构的氧化物颗粒以固溶体形式均匀分布在ATP表面,颗粒尺寸约5~10 nm;随Ti⁴⁺的进一步增加,样品中的CeO₂结晶不完全;当Ce/Ti<3/7时,样品中出现锐钛矿型TiO₂的分离相。适量的Ti⁴⁺掺杂能促进CeO₂产生较多的结构缺陷,有利于增加晶格氧空位的浓度,提高样品的催化活性。对罗丹明B的催化降解实验表明,当Ce/Ti=5/5时,样品的催化性能较好,对罗丹明B溶液的化学需氧量(COD)去除率可达96%以上。     

Zn-Mg复合氧化物催化大豆油甘油解合成单甘酯

采用共沉淀法制备了一系列不同Zn、Mg物质的量比的Zn-Mg复合氧化物,将其用于催化大豆油甘油解合成单甘酯(MG),采用XRD、氮气吸附-脱附仪、SEM、TEM对Zn-Mg复合氧化物结构与性能进行了表征,并测定了催化剂的表面碱强和碱量。优化了合成单甘酯的工艺条件,并考察了Zn-Mg复合氧化物的重复使用性能。结果表明,改变Zn、Mg物质的量比不仅可以调控Zn-Mg复合氧化物的碱强与碱量,还可以调控其比表面积、孔容等结构参数;不同Zn、Mg物质的量比复合氧化物的催化活性变化趋势与其碱强度(H)在15.0H17.2间碱量变化趋势相一致;n(Zn)/n(Mg)=0.1时,复合氧化物(ZM0.1)具有最好的催化甘油解反应活性;使用该催化剂合成单甘酯的适宜条件为:n(甘油)∶n(大豆油)=3∶1,反应温度210℃,反应时间2 h,催化剂用量为大豆油质量的0.6%,该条件下大豆油转化率达95.6%,单甘酯收率为58.5%。ZM0.1催化剂重复使用4次时大豆油转化率仍达80.9%。     

Partial Oxidation of Methanol to Formaldehyde on Molybdenum Based Mixed Oxide Catalyst

Molybdenum based mixed oxide containing Mo_0.65V_0.25W_0.10 was investigated for the partial oxidation of methanol. The structural property and catalytic activity of the mixed oxide catalyst was studied by surface area (BET), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). The thermal activation of the catalyst resulted increase in the conversion of methanol and the selectivity to formaldehyde. The thermal activation of the MoVW mixed oxide in nitrogen atmospheres induces partial crystallization of a Mo₅O₁₄-type oxide at 813 K. The SEM images of the thermally activated catalyst show needle like particles. These particles were agglomerates of platelet-like crystallites of a few hundreds of nanometers in size. SEM and EDX techniques show that the mixed oxide is characterized by an inhomogeneous elemental distribution on the length scale of a few microns. XRD of the thermally activated catalyst showed a nanocrystalline material identified as a mixture of Mo₅O₁₄, MoO₃ and MoO₂-type MoVW oxides. The catalytic activity of the MoVW mixed oxide show a good conversion of methanol and selectivity to formaldehyde.     

Supermicroporous Niobium Oxide as an Acid Catalyst

Supermicroporous (1.5–2.5 nm pore diameter) niobium oxide is synthesized using a nonionic block copolymer as a structural directing reagent, which is removed by water washing after aging. The oxide contains water in the bulk material in the form of a water-rich niobium oxide. The supermicroporous niobium oxide is applicable for various acid-catalyzed reactions.     

Chemoselective Hydrogenation of the Olefinic Bonds Using a Palladium/Magnesium‐Lanthanum Mixed Oxide Catalyst

A palladium/magnesium‐lanthanum mixed oxide catalyst is found to be an efficient heterogeneous catalyst for the chemoselective hydrogenation of olefinic double bonds in the presence of various functional groups. The catalyst was recovered by centrifugation and reused for several cycles with consistent activity and selectivity.     

Recent Advances on TiO2-ZrO2 Mixed Oxides as Catalysts and Catalyst Supports

This is the first review of titanium dioxide-zirconium dioxide (TiO₂-ZrO₂) mixed oxides, which are frequently employed as catalysts and catalyst supports. In this review many details pertaining to the synthesis of these mixed oxides by various conventional and nonconventional methods and their characterization by several techniques, as reported in the literature, are assessed. These mixed oxides have been synthesized by different preparative analogies and were extensively characterized by employing various spectroscopic and nonspectroscopic techniques. The TiO₂-ZrO₂ mixed oxides are also extensively used as supports with metals, nonmetals, and metal oxides for various catalytic applications. These supported catalysts have also been thoroughly investigated by different techniques. The influence of TiO₂-ZrO₂ on the dispersion and surface structure of the supported active components as examined by various techniques in the literature has been contemplated. A variety of reactions catalyzed by TiO₂-ZrO₂ and supported titania-zirconia mixed oxides, namely; dehydrogenation, decomposition of chlorofluoro carbons (CFCs), alcohols from epoxides, synthesis of ε-caprolactam, partial oxidation, deep oxidation, hydrogenation, hydroprocessing, organic transformations, NO_x abatement, and photo catalytic VOC oxidations that have been pursued in the literature are presented with relevant references.     

在微波辐射作用下制备纳米CeO2及其表面改性研究

本文以Ce(SO4)2·4H2O和NaOH为反应原料,用表面活性剂聚乙二醇(PEG)分散和保护产品,在微波辐射作用下制备了纳米CeO2.采用红外光谱仪、X射线衍射仪和差热热重联用分析仪对所制得的产品进行表征,产品颗粒粒径为24.9 nm.为了扩大所制备的纳米CeO2的应用范围,用表面活性剂月桂酸钠对其进行表面改性研究,结果表明该工艺具有高效、环保、产品分散性好、粒径小和易于推广等优点.     

A Nano-Hybrid of Molybdenum Oxide Intercalated by Dithiocarbamate as an Oxidation Catalyst

A novel nano-layered material based on molybdenum oxide has been synthesized by hydrothermal method using dithiocarbamate. On the basis of the X-ray diffraction, scanning electron microscopy, thermal analysis and infrared spectroscopy results, a possible arrangement of organic ligands in the interlayer space of molybdenum oxide has been proposed. Moreover, the catalytic activity of the synthesized nanohybrid of molybdenum oxide was investigated in oxygen transfer reactions. This reagent can oxidize alkenes, alcohols, sulfides, and amines in the presence of hydrogen peroxide with high yield and selectivity.     

TiO2-SiO2复合氧化物的理化性质及其对柴油加氢精制性能的影响

采用溶胶-凝胶法结合CO₂超临界流体干燥技术制备了不同Ti/Si原子比的TiO₂-SiO₂复合氧化物（TS-n）,考察了Ti/Si原子比、焙烧温度对复合氧化物比表面积、孔结构、酸性及原子结合状态的影响,通过重油催化裂化柴油加氢精制反应考察了以TS-1、TS-4为载体的催化剂脱硫性能的差异.结果表明,TiO2经SiO2复合改性后,热稳定性和晶态稳定性大幅度提高;TiO₂-SiO₂复合氧化物的酸性及原子间的相互作用与Ti/Si原子比有直接的关系;载体的晶态组成及酸性和催化剂的酸性对催化剂的加氢脱硫性能有显著影响,复合氧化物中锐态型TiO₂的存在强化了载体与金属组分之间的相互作用,提高了催化剂的加氢脱硫活性,不同类型的酸性中心对柴油中不同类型的硫化物具有不同的脱除能力,Bronsted 酸中心较多的催化剂对结构简单的硫化物脱除能力强,Lewis酸中心较多的催化剂对结构复杂的硫化物有较好的脱除效果.     

TiO2基硫磺回收催化剂在辽河石化公司的应用

辽河石化公司自建硫磺回收装置以来,一直使用Al2O3基催化剂,由于酸性气浓度、组成等自身特点,该催化剂对有机硫的水解率不高,导致尾气部分负荷增加,给尾气达标排放带了很大的困难,考虑到自身装置的特点,于2010年装置检修时更换为TiO2基型制硫催化剂,无论从适应实际操作条件,硫转化率,有机硫水解率都起到了很好的效果。     

Transesterification of Canola Oil to Biodiesel Using CaO/Talc Nanopowder as a Mixed Oxide Catalyst

A series of heterogeneous catalysts including different molar ratios of CaO/talc was synthesized to study the transesterification reaction of canola oil and methanol under different reaction conditions. Characterization and kinetic results revealed that the activity of this catalyst was enhanced due to the increase of CaO/talc molar ratio value leading to an improvement in the biodiesel production. Moreover, the effect of various parameters on the activity of the undertaken catalysts was studied in order to determine the optimum process conditions. Leaching measurements and the durability of the CaO/talc catalyst under several reaction cycles were evaluated and proved it to be a stable catalyst.