乙二胺基和2,4-戊二酮官能化介孔分子筛固载钼(VI):新型的环己烯环氧化催化剂

通过对介孔分子筛HMS和MCM 41表面修饰 ,将乙二胺基和 2 ,4 戊二酮引入到介孔分子筛孔道内 ,制备出乙二胺基和戊二酮官能化介孔分子筛 .首次将烯烃环氧化均相催化剂MoO2 (acac) 2 固载到乙二胺基和戊二酮官能化介孔分子筛孔道内 ,制备出新型的、易回收、可重复使用的烯烃环氧化多相催化剂 .环己烯催化环氧化表明 ,该催化剂的催化活性与均相催化剂MoO2 (acac) 2 相当 ,选择性大于 80 %.     

CoPc/Al2O3催化分子氧环氧化环己烯的研究

常使用均相催化剂[1-4]催化氧化剂对烯烃进行环氧化来制备环氧环己烷,但均相催化剂存在分离回收难,易二聚失活的缺点.近年来对均相催化剂的固载开展了广泛的研究,如郑岩等[5]使用溶胶 -凝胶包容乙酰丙酮镍,M.Salavati-Niasari等[6]用Al2O3固载Mn(Salen)、Mn(en)2和Mn(acac)2金属配合物用于烯烃环氧化,由于Al2O3廉价易得,酞菁具有不易二聚、降解等较稳定的优点[3],本文以酸性Al2O3为载体,固载酞菁钴金属配合物制备CoPc/Al2O3新型环氧化催化剂,并对其结构进行表征,同时以分子氧为氧源,异丁醛为还原剂考察CoPc/Al2O3催化剂对环己烯的催化环氧化活性,探索了环己烯环氧化的较佳工艺参数.     

有机官能团化介孔分子筛固载铑膦配合物的制备及其对己烯-1氢甲酰化的催化性能

 制备了表面有机官能团化的MCM-41和MCM-48介孔分子筛以及SiO2等载体固载铑膦配合物催化剂,考察了所制备催化剂对液相己烯-1氢甲酰化的催化性能,并用X射线衍射、BET、红外光谱和原子吸收光谱等技术对载体和催化剂的组成和结构进行了表征. 结果表明,固载化铑膦配合物对烯烃氢甲酰化的催化性能与有机官能团的种类及载体的结构有关; 固载于含胺基和腈基有机官能团化介孔分子筛载体的铑膦配合物表现出较高的催化活性和稳定性.     

一种新的烯烃环氧化催化剂MBC的合成及其催化作用的研究

为了克服以往许多烯烃环氧化催化剂发生严重沉积的缺点,我们首次合成了一种苯乙二醇氧钼螯合物(简称M BC,M为MoO_2,B为苯乙二醇,C为螯合物).将其用于丙烯环氧化新反应中,可以免去助溶剂,苯乙二醇配位体原料可重新由该过程获得,各反应指标均较满意,较好地消除了沉积,表明MBC是个良好的环氧化催化剂.     

共缩聚法制备的咪唑官能化介孔材料固载手性Mn（Ⅲ）salen催化烯烃环氧化反应

采用共缩聚法制备的咪唑官能化介孔材料共价固载手性Mn（Ⅲ）salen络合物,得到的催化剂中活性组分以离子物种的形式存在．XRD、FrlR、DRUV-vis和N2吸附的结果表明,手性Mn（Ⅲ）salen络合物被成功固载在了载体的孔道中,并且得到的催化剂保持了介孔载体的特征孔道结构．该非均相催化剂在非官能团化烯烃的不对称环氧化反应中表现出了与相应的均相催化剂相当的催化活性和对映选择性．并且,采用较少用量的非均相催化剂即能在较短的反应时间内得到很高的催化活性,这可能与催化剂中活性组分的离子性能以及均匀分布有关．     

手性酮催化的烯烃不对称环氧化反应

手性酮是催化非官能化烯烃不对称环氧化的一类重要催化剂 ,它与过氧硫酸氢钾可原位产生对贫电子和富电子烯烃均很有效的氧化剂———手性二氧杂环丙烷 .综述了各种结构的手性酮在反式烯烃、三取代烯烃和顺式烯烃等的不对称环氧化反应中的应用研究进展 ,总结了手性酮结构及反应条件对其催化活性和不对称诱导作用的影响     

席夫碱Mo(VI)功能化介孔SiO2的制备及其催化烯烃环氧化研究

采用共缩聚法制备有机-无机杂化材料,以介孔SiO_2材料为载体,分别嫁接席夫碱配体和配位乙酰丙酮钼,得到Mo(VI)席夫碱修饰的介孔SiO_2(Mo-SB-Cl-SiO_2-0.5-1).所制备的材料采用XRD,SEM,N2吸附-脱附和TEM技术对其结构进行了表征.考察了Mo-SB-Cl-SiO_2-0.5-1催化液相烯烃环氧化性能,结果表明:Mo-SB-Cl-SiO_2-0.5-1催化剂对烯烃环氧化具有高的转化率和优良的催化活性.与后嫁接法制备的催化剂相比,Mo-SB-Cl-SiO_2-0.5-1催化剂催化活性得到明显提高,催化环己烯环氧化的转化率和选择性分别为85%和99%.在不同烯烃的研究中,环辛烯具有最高的转化率和选择性,分别为87%和99%.催化剂重复使用4次后,环己烯的转化率没有明显下降,选择性仍然高达98%,表明Mo-SB-Cl-SiO_2-0.5-1具有较好的催化稳定性.     

有机官能化介孔硅基材料负载纳米金催化剂的制备及其催化性能

一步合成了桥键嵌入二硫醚官能化介孔硅基材料(PMO-SBA-15),利朋介孔硅基材料孔道内表面的二硫醚基团捕获纳米金(Au)粒子的作用,获得了负载型纳米Au催化剂(Au-PMO-SBA-15).小角X射线衍射和低温N2吸附-脱附的结果表明,PMO-SBA-15和Au-PMO-SBA-15均保持典型的介孔结构;高分辨透射电镜观察到纳米Au粒子在载体孔道内分散均匀,甲均粒径为(2.2±0.2)nm.以70%的叔丁基过氧化氧水溶液为氧化剂,考察了纳米Au催化剂Au-PMO-SBA-15在苯甲醇氧化反应中的催化性能.结果表明,当反应温度为353 K、反应时间为5 h时,苯甲醇的转化率为29.1%,苯甲醛的选择性为100%,且催化剂重复使用7次其催化活性和苯甲醛选择性基奉不变.     

氨丙基官能化HMS介孔分子筛的合成及表征

沿S0I0路径,以十六胺为模板剂,以3-氨丙基三乙氧基硅烷为有机硅源,通过与TEOS共水解沉淀合成了氨丙基官能化HMS介孔分子筛.采用粉末X-射线衍射分析、N2吸/脱附、扫描电镜分析、高分辨透射电镜分析、傅立叶变换红外分析以及元素分析等表征手段,对所合成的材料进行表征.氨丙基官能化HMS介孔分子筛具有worm-like孔道结构,且较为均一的孔径分布.研究了前体硅源中3-氨丙基三乙氧基硅烷含量的变化对氨丙基官能化HMS介孔分子筛的相结构及织构性能的影响.傅立叶变换红外分析表明,NH2-CH2-CH2-CH2有机基团分布在杂化HMS介孔孔道中.     

六氟代戊二酮合镍/乙氧基二乙基铝催化丙烯的线性齐聚

丙烯二聚和齐聚生成高碳直链烯烃的研究已经引起人们的注意.Keim使用单组份催化剂六氟代戊二酮、1,5-环辛二烯镍络合物、Jones使用双组份催化剂β-戊二酮合镍/乙氧基二乙基铝、作者使用六氟代戊二酮合镍/三异丁基铝催化丙烯齐聚反应,都得到了直链烯烃含量较高的丙烯齐聚物.但是,上述各体系的催化剂活性相差很大.本文简要报道以甲苯为溶剂,六氟代戊二酮合镍/乙氧基二乙基铝〔简称(Hfacac)_2Ni/Et_2AlOEt〕为催化剂的丙烯齐聚反应的规律.     

多孔材料负载金催化剂的制备与应用*

本文综述了微孔材料和介孔材料负载型金催化剂的制备、表征与应用研究的最新进展,从多孔载体的选择（氧化物、微孔分子筛、介孔氧化物、介孔分子筛和介孔碳材料）、金的最新负载方法（沉积-沉淀法、溶胶-凝胶法、原位法/一步法和化学气相沉积法）与表征及其催化性能（一氧化碳低温氧化、氢气/氧气直接合成过氧化氢、直接合成环氧丙烷和有机物的选择性氧化）等方面详尽地评述了微孔材料和介孔材料负载型金催化剂研究概况。同时,提出了多孔材料负载金催化剂存在的一些问题,并展望了其研究和发展的方向。     

W-SBA-15介孔分子筛的直接合成及其对环己烯环氧化反应的催化性能

 分别以Na2WO4和H2WO4为钨源,以正硅酸四乙酯为硅源直接合成了W-SBA-15介孔分子筛样品,并用小角XRD,N2吸附,FT-IR,UV-Vis,SEM和XRF等手段对合成的分子筛进行了表征. 结果表明,只用P123(EO20PO70EO20)为模板剂时,分子筛中钨的含量只是投料量的一半; 而以P123和十六烷基三甲基溴化铵为混合模板剂时,钨能有效地掺杂到SBA-15分子筛中. 当原料中的Si/W摩尔比为40时,W-SBA-15分子筛中的钨物种以高度分散状态存在,且以H2WO4为钨源比以Na2WO4为钨源更易将钨掺杂到SBA-15介孔分子筛中. W-SBA-15分子筛催化剂对环己烯环氧化反应具有较高的催化活性.     

钛硅分子筛催化1-丁烯环氧化研究

自1983年Taramasso等报导TS-1的合成以来,钛硅分子筛的合成及应用一直是分子筛催化领域的热点。经典TS-1合成方法采用四丙基氢氧化铵（TPAOH）为模板剂,合成成本较高、条件苛刻,限制了其应用。用四丙基溴化铵（TPABr）为模板剂代替TPAOH,能够成功地合成TS-1。不同孔道结构的钛硅分子筛,如Ti-β、Ti-MCM-41、Ti-HMS等弥补了TS-1较小孔径的缺点,进一步扩大了钛硅分子筛的应用。本文以不同合成方法得到的TS-1及中孔Ti—HMS为催化剂,双氧水为氧化剂,1-丁烯环氧化合成1,2-环氧丁烷,研究了不同钛硅分子筛对1-丁烯环氧化反应的催化性能。     

Chiral ruthenium porphyrin encapsulated in ordered mesoporous molecular sieves (MCM-41 and MCM-48) as catalysts for asymmetric alkene epoxidation and cyclopropanation

Encapsulation of chiral ruthenium porphyrin [RuII(D4-Por*)CO] in modified mesoporous silica supports such as MCM-41 and MCM-48 achieves active catalysts for asymmetric epoxidation of alkenes by 2,6-dichloropyridine N-oxide and intramolecular cyclopropanation, which is the first example of chiral metalloporphyrin supported on ordered molecular sieves.     

Silica-supported,single-site titanium catalysts for olefin epoxidation. A molecular precursor strategy for control of catalyst structure

A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.     

Comparative Study of Titanium-modified HMS Mesoporous Materials via Different Preparing Methods

The current work is focused on the testing of titanium modified hexagonal mesoporous silica (HMS) for catalysts in epoxidation of cyclohexene. Two samples were prepared via the chemical liquid deposition (CLD) and the chemical vapor deposition (CVD), namely Ti/HMS-L and Ti/HMS-V, respectively. HMS and Ti/HMS were characterized by XRD, N₂-adsorption, ICP-AES, UV-Vis. The samples were also evaluated by the epoxidation of cyclohexene with cumene hydroperoxide (CHP) as oxidant. It is revealed that Ti/HMS samples possess typical hexagonal mesoporous structure in which most of titanium species exist in the form of framework tetracoordinated state. Meanwhile, Ti/HMS-V is more seriously affected than Ti/HMS-L since the former was prepared at higher temperature. Ti/HMS-V gives more excellent catalytic performance than Ti/HMS-L, which is likely because the former has more isolated and framework titanium species. Either Ti/HMS-V or Ti/HMS-L can be used only 1 time in epoxidation experiment.     

Preparation of mesoporous molecular sieve based hydrocracking catalysts

A series of hydrocracking catalysts based on mesoporous molecular sieves MCM-41 and SBA-15 with different silica to alumina ratios was prepared. Nickel and molybdenum were used as active metals to impregnate the extrudates prepared by using molecular sieves. The catalysts were characterized for physical and chemical properties and evaluated for the hydrocraking of desulfurised vacuum gas oil. The conversion of DS-VGO was lower as compared to that of the catalyst based on USY zeolite. However, the gas yield was lower in case of mesoporous materials based catalysts.     

An efficient hybrid, nanostructured, epoxidation catalyst: titanium silsesquioxane-polystyrene copolymer supported on SBA-15

A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active center, was immobilized successfully by in-situ copolymerization on a mesoporous SBA-15-supported polystyrene polymer. The resulting hybrid materials exhibit attractive textural properties (highly ordered mesostructure, large specific surface area (>380 m2 g-1) and pore volume (>or==0.46 cm3 g-1)), and high activity in the epoxidation of alkenes. In the epoxidation of cyclooctene with tert-butyl hydrogen peroxide (TBHP), the hybrid catalysts have rate constants comparable with that of their homogeneous counterpart, and can be recycled at least seven times. They can also catalyze the epoxidation of cyclooctene with aqueous H2O2 as the oxidant. In two-phase reaction media, the catalysts show much higher activity than their homogeneous counterpart due to the hydrophobic environment around the active centers. They behave as interfacial catalysts due to their multifunctionality, that is, the hydrophobicity of polystyrene and the polyhedral oligomeric silsesquioxanes (POSS), and the hydrophilicity of the silica and the mesoporous structure. Combination of the immobilization of homogeneous catalysts on two conventional supports, inorganic solid and organic polymer, is demonstrated to achieve novel heterogeneous catalytic ensembles with the merits of attractive textural properties, tunable surface properties, and optimized environments around the active sites.     

Immersion calorimetry as a tool to evaluate the catalytic performance of titanosilicate materials in the epoxidation of cyclohexene

Different types of titanosilicates are synthesized, structurally characterized, and subsequently catalytically tested in the liquid-phase epoxidation of cyclohexene. The performance of three types of combined zeolitic/mesoporous materials is compared with that of widely studied Ti-grafted-MCM-41 molecular sieve and the TS-1 microporous titanosilicate. The catalytic test results are correlated with the structural characteristics of the different catalysts. Moreover, for the first time, immersion calorimetry with the same substrate molecule as in the catalytic test reaction is applied as an extra means to interpret the catalytic results. A good correlation between catalytic performance and immersion calorimetry results is found. This work points out that the combination of catalytic testing and immersion calorimetry can lead to important insights into the influence of the materials structural characteristics on catalysis. Moreover, the potential of using immersion calorimetry as a screening tool for catalysts in epoxidation reactions is shown.