用催化剂表面修饰以进行苯选择加氢制环己烯的研究

1 前言常规的气相苯催化加氢反应,苯环大π键一经打开就全部加氢到底,产物中只能获得环己烷而极难得到选择加氢产物环己烯。生成环己烷的反应从热力学上看远比生成环己烯的反应容易进行很多,并且环己烯也非常容易进一步加氢生成环己烷。但催化剂的表面经修饰剂作用后可根本改变其性能,从而改进催化活性及选择性,或实现常规方法不可能实现的反应,获得不易得到的产物。在经表面修饰的催化剂上进行苯加氢反应可获得选择加氢产物环     

环己烯水合制环己醇研究进展

综述了环己烯水合反应制环己醇的催化剂及水合催化工艺的研究进展;分析了环己烯水合催化剂及工艺存在的问题。环己醇生产用环己烯水合催化剂主要为分子筛,其性能稳定,易分离,可循环使用。环己烯水合工艺存在催化剂消耗量大,转化率低。开发反应精馏新工艺及其对应的离子交换树脂催化剂是今后环己烯水合反应的研究方向。     

Preparation of Titanium-Containing Carbon–Silica Composite Catalysts and Their Liquid-Phase Epoxidation Activity

Titanium-containing catalysts have been prepared by two different post-synthesis methods using activated carbon and carbon-silica composite as catalyst supports. They have been applied to the liquid-phase epoxidation of cyclohexene with tert-butyl hydroperoxide (TBHP) and H₂O₂. The carbon-silica composite catalyst showed a high conversion and selectivity to epoxide compared to the Ti-carbon catalyst and silica-based catalysts for the cyclohexene epoxidation with H₂O₂. The highest values of cyclohexene conversion and epoxide selectivity were obtained with the carbon-silica composite catalyst having a titanium content of 3 wt%.     

硅烷化含钛介孔分子筛催化环己烯环氧化动力学

研究了气相沉积法制备的硅烷化含钛介孔分子筛(Ti/HMS)催化环己烯与异丙苯过氧化氢(CHP)的环氧化反应的宏观动力学.结果表明:环己烯与CHP的环氧化反应对催化剂的量表现为1级;对于环己烯和氧化剂CHP,随着浓度的增加,反应随之由1级向0级过渡,根据实验结果和反应机理,运用Rideal-Eley方法,提出了硅烷化Ti/HMS催化环己烯与CHP环氧化反应的动力学方程.     

C6~C8烯烃水合催化剂的研究进展

环己烯、正己烯、正辛烯等C₆~C₈烯烃是重要的化工原料,用途广泛。综述了环己烯及正己烯,正辛烯等C₆~C₈烯烃水合催化剂的研究进展。环己烯水合法制备环己醇是一种绿色制备工艺,其催化剂由最初的硫酸、磺酸等均相催化剂逐渐向分子筛等非均相催化剂过渡,其中HZSM-5分子筛以其高选择性、高活性成为工艺上常用的催化剂。环己烯间接水合法合成环己醇的途径具有高选择性,高转化率,低能耗的优点,其催化剂的研究也处在一个高速发展阶段。正己烯、正辛烯水合催化剂的研究较少。未来离子液体等新型水合催化剂将会成为环己烯水合制备环己醇的研究重点。     

The partial gas‐phase hydrogenation of benzene to cyclohexene on supported and coated ruthenium catalysts

The conversion of benzene to useful products such as cyclohexene is of industrial interest because of the expected surplus of benzene due to its substitution in gasoline by other nonpolluting components in the next years. Therefore, the partial gasphase hydrogenation of benzene to cyclohexene at atmospheric pressure was performed in order to develop catalysts as an alternative to those used in liquidphase hydrogenation. Two types of rutheniumcontaining catalysts were investigated, viz. supported catalysts with different support materials and coated catalysts with electrolytically formed alumina as support. In order to yield the desired cyclohexene the presence of methanol as a reaction modifier was necessary in the gas phase during the reaction. The hydrogenation on supported Ru catalysts gave selectivities of about 35%, while on coated Ru catalysts selectivities up to 45% were obtained at conversion degrees of 5%. Improved catalyst performance, especially higher selectivity and yield, was obtained at increased partial pressure of methanol and hydrogen and by addition of copper as second metal in the oxide layer of the coated catalysts.     

环己烯分子氧氧化多相催化剂研究进展

根据催化剂主组分的不同,综述了国内外环己烯分子氧氧化多相催化剂的研究进展;主要介绍了钴系、锰系、铁系及镍系催化剂在环己烯分子氧氧化中的应用及其优缺点.指出负载型纳米金催化剂与传统的钴、锰催化剂相结合制备双活性中心催化剂在环己烯分子氧氧化中有较好的应用前景.     

The Role of the Support in the Oxidative Destruction of Chlorobenzene on Pt/Zeolite Catalysts: An FT-IR Investigation

The vapor-phase cyclohexane oxidative dehydrogenation has been investigated over several catalysts. A typical catalyst for total oxidation, as Mn₂O₃, materials applied in the field of oxide hydrogenation reactions, as silica-supported vanadia- and niobia-based catalysts, V-, Fe-, and Ce-phosphates used for partial oxidation reactions and ZSM5 zeolite, protonic and Co exchanged, have been tested. Over almost all the catalysts, benzene is the main product obtained, although cyclohexene is obtained with high selectivity at low conversion on phosphate catalysts.     

Epoxidation of Cyclohexene with Air over the Composite Catalysts of Mn-mont Coordinated with Ligands

The catalytic activity of the composite catalysts of Mn-mont (where mont represents montmorillonite) coordinated with ligands for the epoxidation of cyclohexene by air under Mukaiyama conditions was studied. The composite catalysts were characterized by atomic absorption spectroscopic analysis, elemental analysis, fourier transform infrared spectra, diffuse reflectance ultraviolet visible spectra, X-ray photoelectron spectroscopy, powder-X-ray-diffraction, and scanning electron microscopy measurements. The effects of various reaction conditions on the catalytic reaction were studied. Experimental results indicated that the catalysts performed excellent activity for the epoxidation of cyclohexene by air. Repeated runs indicate that the catalyst is stable for 3 cycles. The composite catalysts of Mn-mont coordinated with ligands are economical and environmentally friendly for the epoxidation of cyclohexene.     

苯选择性加氢Ru/TiO_2催化剂载体晶型效应研究

以不同晶型的TiO_2为载体采用化学还原浸渍法制备了三种Ru/TiO_2催化剂,并利用X射线衍射(XRD)、N_2吸附-脱附、透射电镜(TEM)、NH_3程序升温脱附(NH_3-TPD)和傅里叶变换红外光谱(FTIR)等表征手段研究了催化剂的物理化学性质,考察了其在苯选择性加氢反应中的催化性能。结果表明:苯选择性加氢活性与Ru/TiO_2催化剂的Ru粒子分散度有关,Ru粒子分散度越高,催化活性越高;而环己烯选择性与Ru/TiO_2催化剂的酸量呈负相关,Ru/TiO_2-P催化剂的酸量最低,对环己烯的吸附量最低,在相同转化率下苯加氢生成环己烯的选择性最高。动力学分析表明,苯加氢生成环己烯的反应速率常数(k_1)与环己烯加氢生成环己烷的反应速率常数(k_2)的比值与环己烯收率呈近似正相关。     

环己烷气相氧化脱氢催化剂的研究进展

为了尽可能多地获得环己烯和充分利用苯选择加氢反应的副产物环己烷,环己烷氧化脱氢反应在近 20 年内得到迅速发展.环己烷氧化脱氢反应催化剂体系的选择对于获得较高的环己烯产率和选择性、较低的氧化脱氢反应温度以及最优的反应路径尤为重要.详细阐述了阳离子沸石催化剂、复合金属氧化物催化剂以及贵金属丝网催化剂等在环己烷氧化脱氢制取...     

Efficient catalysts with controlled porous structure obtained by anodic oxidation under spark-discharge

The anodic oxidation under spark discharge (ANOF technique) is presented as a promising alternative for the preparation of catalytic oxide layers on metallic supports. The influence of the substrate (Al, Ti, and Mg), electrolyte composition and the treatment time to obtain egg-shell catalysts with tailor-made properties for the effective oxydehydrogenation (ODH) of cyclohexane to cyclohexene is studied. Chromium, molybdenum and nickel were chosen as precursors for active species in order to obtain catalysts able to perform the substrate oxidation by electrophilic (chromium oxide), nucleophilic (molybdena) or both kind of oxygen species (nickel oxide). It was found that compared to nickel oxide, the chromium oxide containing egg-shell catalyst was less selective while the molybdenum oxide showed very high selectivity, but lower activity. The intrinsic activity of nickel containing egg-shell catalysts is an order of magnitude higher than that of a classic alumina supported nickel oxide catalyst obtained by impregnation. The selectivity to the intermediate cyclohexene is also favored on the egg-shell catalyst with a regular pore structure. Moreover, the selectivity performance of the catalysts can be improved by designing catalysts with shorter pores.     

Epoxidation of Cyclohexene With H2O2 and Acetonitrile Catalyzed by Mg–Al Hydrotalcite and Cobalt Modified Hydrotalcites

The paper presents a comparison between the results obtained for cyclohexene epoxidation in the presence of base catalysts: Mg_0/75Al_0.25-hydrotalcite (HT), the corresponding mixed oxide (CHT), the reconstructed hydrotalcite (RHT), a hydrotalcite containing cobalt in the brucite-type layer ((Co-Mg_0.75)Al_0.25)) and one containing cobalt complex-species supported on HT carrier (Co-complex/HT). The selective conversion of cyclohexene to the corresponding epoxide is closely related to the base strength of the catalysts.     

Partial hydrogenation of benzene with ruthenium catalysts prepared by a chemical mixing procedure: Preparation and properties of the catalysts

Ruthenium catalysts were prepared in different alcohols by a chemical mixing technique, characterised by the preparation of a homogeneous solution containing catalyst components, and the uniform coagulation of the solution through hydrolysis. The technique has the potential for controlling the surface area of the catalysts and for making them porous. The ruthenium catalysts were much more effective for the partial hydrogenation of benzene to cyclohexene (maximum cyclohexene yield, 31.4%) in the absence of any poison such as alkali metal hydroxide or transitional metal sulphate in the reaction solution.     

环己醇脱水制备环己烯催化剂综述

综述了环己醇脱水制备环己烯的硫酸氢钠、四氯化锡、对甲基苯磺酸、硅铝酸盐、固体超强酸、活性白土、分子筛等催化剂研究结果,催化活性较高的为对甲基苯磺酸、硅铝酸盐、固体超强酸和活性白土,有一定的应用前景。     

Amine-modified titania–silica mixed oxides: 1. Effect of amine concentration and activation temperature towards epoxidation of cyclohexene

Titania–silica mixed oxides with covalently bound 3-aminopropyl groups were prepared by keeping the amount of tetrabutylorthotitanate as fixed and varying the 3-aminopropyltriethoxy silane and tetraethylortho silicate precursors using sol–gel process. The samples are characterised to know the specific surface area, surface oxygen and hydrophilicity/hydrophobicity index. Epoxidation of cyclohexene with hydrogen peroxide is carried out over these catalysts as a function of amine concentration and activation temperature. The conversion of cyclohexene and selectivity towards cyclohexene oxide is directly correlated with the surface area as well as surface oxygen and hydrophobicity of the catalyst, respectively.     

Research progress of catalysts for selective hydrogenation of benzene to cyclohexene

目前苯选择加氢制环己烯催化剂已广泛应用于合成纤维工业及其它领域中。本文综述了国内外苯选择加氢制环已烯催化剂的研究现状,重点介绍了活性组分、载体、助剂、制备方法及添加剂对催化剂活性及选择性的影响,分析了其影响原因,并指出了提高环己烯选择性的关键因素,最后在此基础上展望了苯选择加氢催化剂的发展方向。     

Cyclohexene hydrogenation on rhodium catalysts in the gas phase: Kinetics of the reaction and origin,mechanism and kinetics of the deactivation process: Kinetics of the reaction and origin,mechanism and kinetics of the deactivation process

Cyclohexene hydrogenation in the gas phase was studied on bulk or supported rhodium catalysts between 270 and 290 K. The kinetic data for cyclohexene hydrogenation were determined under the initial conditions. The catalyst deactivation during this reaction was shown to obey a second order kinetic law. Temperature-programmed desorption (TPD) showed that benzene was formed during the reaction. The deactivation process was due to the stronger adsorption and to the lower reactivity of benzene produced by disproportionation of cyclohexene. A mechanism is proposed to correlate the deactivation of rhodium catalysts and the hydrogenation of cyclohexene.     

Synthesis and Characterization of Dendrimer-Templated Mesoporous Oxidation Catalysts

We report here the use of 4th and 5th generation dendrimers poly(propylene)imine (CU-D32 and CU-D64) as templating agents for the synthesis of mesoporous titanosilicate and vanadosilicate oxidation catalysts via solgel techniques. The physical properties of these mesoporous materials were characterized by TGA, BET, PXD and SEM/EDX analyses and these showed that the transition metals are evenly distributed throughout these silicates, which have interconnected spherical pores (approx. 12Å in diameter) and high surface areas of about 650m²g^–1. Kinetic studies showed that all transition metal-doped catalysts were highly selective at oxidizing cyclohexene to the corresponding epoxide. Additionally, CU-D64-templated catalysts were more catalytically active for cyclohexene epoxidation than CU-D32-templated catalysts as a result of differences in pore size. All CU-D64-templated catalysts exhibited epoxidation catalytic activity comparable to that of titanium doped MCM-41 materials.     

教学实验室中无机盐催化合成环己烯的探讨

讨论了教学实验室中环己醇脱水制备环己烯的硫酸氢钠、氯化亚锡、氯化铁等催化剂研究。结果表明,氯化亚锡对于催化环己醇脱水生成环己烯有比较好的作用,且可重复使用,不会造成环境污染。