环己烯环氧化制备环氧环己烷的方法

本本发明提供一种环己烯环氧化制备环氧环己烷的方法,主要解决现有技术中存在催化剂活性低、环氧环己烷选择性低的问题。该方法以环己烯为底物,乙腈为反应溶剂,叔丁基过氧化氢溶液为氧化剂,在片层厚度不超过20nm、骨架钛摩尔含量不低于2%的薄层、高骨架钛含量的Ti-MWW分子筛催化剂上进行烯烃环氧化反应,反应结束后将反应液精馏处理,取130℃～135℃的馏分,得到环氧环己烷。本发明的方法环己烯转化率高、目标产物环氧环己烷的选择性高,可用于环氧环己烷的工业生产。     

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.     

V-MCM-41催化环己烯环氧化性能

采用水热法合成了V-MCM-41,并用ICP-AES、FTIR、DRS-UV-Vis、XRD、BET等技术对其进行了表征,发现只有部分V进入分子筛,所合成的V-MCM-41具有较高的结晶度,并且其结晶度随晶化液中V/Si摩尔比的增大而升高。V-MCM-41催化环己烯/H₂O₂氧化反应结果表明,当V-MCM-41中V含量大于1.10%（摩尔分数）时,骨架V-O-V物种在催化环己烯氧化反应的同时,也可加速H₂O₂的分解;乙腈是该反应体系的最佳溶剂,最佳反应温度为70℃。最佳反应结果表明,环己烯的单程转化率和H₂O₂有效利用率可分别达到23.91%和95.4%。     

晶化时间对敞开体系合成Ti-MCM-41的影响

在敞开体系中,以工业用水玻璃为硅源,TiCl3为钛源,十六烷基三甲基溴化铵(CTMAB)为模板剂,用H2SO4调节浆料的pH值,浆料混合物的物质的量比为n(SiO2):n(Na2O):n(CTMAB):n(TiCl3):n(H2O)=7:2.08:1.4:0.14:530时,373 K搅拌晶化一定时间,合成了Ti-MCM-41,并测试其对环己烯氧化合成环氧环己烷的催化性能.利用X射线衍射( XRD)、红外光谱(FT-IR)、紫外-可见光谱(UV-Vis)和孔结构测定对所合成的样品进行了表征,并讨论了晶化时间对分子筛晶化和催化氧化性能的影响.结果表明:在所考察的晶化时间范围内(0.5～5 d),利用敞开体系都能合成出具有良好长程有序性和结晶度的中孔分子筛Ti-MCM-41;将样品用于催化环己烯合成环氧环己烷,在晶化时间为0.5～3 d的范围内,随着晶化时间的增加,进入分子筛骨架的Ti含量也随之增加,导致介孔硅骨架趋向混乱,使分子筛骨架对称性降低,样品的孔径、比表面积和比孔容减小,但并不影响样品催化氧化活性的增加;晶化3d后,钛含量不再增加,分子筛的孔结构和反应的转化率和选择性也几乎不再变化.     

锰分子筛负载的纳米金催化剂上环己烯氧化研究

用高锰酸钾和硫酸锰在酸性条件下合成的八面体锰分子筛载体(OMS-2)为载体,采用沉积沉淀、浸渍还原、原位合成三种方法制备了OMS-2负载的纳米金催化剂,并进行了X射线衍射(XRD)和透射电镜(TEM)表征。以分子氧为氧化剂,考察了不同反应条件下纳米金催化剂在无溶剂体系中环己烯液相氧化的催化性能。结果表明,沉积沉淀法制备的纳米金催化剂显示出较佳的催化活性,该催化剂在80℃、0.5 MPa、24 h反应条件下,环己烯氧化转化率为39.9%,环己烯醇和环己烯酮的选择性分别为35.5%和51.9%。     

正己烷在HZSM-5分子筛上的催化裂解研究

为筛选反应活性和烯烃选择性相对较高的催化剂用于研究吸热型碳氢燃料的催化裂解,以正己烷的催化裂解作为探针反应,探讨其在不同硅铝物质的量比HZSM-5［n(Si)∶n(Al)=25、36、100］分子筛上催化裂解的反应活性和产物分布。结果表明,正己烷在HZSM-5分子筛上的裂解转化率随温度的升高和分子筛中硅铝物质的量比的减小而增大;裂解产物中乙烯、丙烯和总烯烃的选择性均随裂解温度的升高和分子筛中硅铝物质的量比的增加而增加,在（300~550） ℃,HZSM-5［n（Si)∶n(Al)=36］上的总烯烃收率最高,芳烃含量随分子筛中硅铝物质的量比的增加而减小;基于裂解转化率、烯烃和芳烃收率等因素综合考虑,HZSM-5 n(Si)∶n(Al)=36］分子筛为优选催化剂。     

环己烯液相环氧化催化剂的研究进展

烯烃环氧化是一类重要的有机合成反应 ,其中环己烯经催化环氧化制得的环氧环己烷可广泛用作合成精细化学品的原料。阐述了Mo(Ⅵ )、V(Ⅴ )、Ti(Ⅳ )络合物、过渡金属卟啉络合物等环氧化用催化剂以及无机过氧酸盐、过氧化氢、分子氧、有机过氧酸及烷基过氧化氢等常用氧化剂在环己烯液相环氧化中的应用研究进展。还介绍了无机固体负载催化剂和高分子负载催化剂的负载化方法。最后展望了烯烃环氧化的研究开发趋势。     

固体分子筛上环己烯水合工艺研究

通过对HZSM-5,Hβ,HUSY,HSSY等分子筛催化剂在环己烯水合反应体系中进行活性评价,得到较优的催化剂HZSM-5.考察了搅拌速度、反应温度、反应时间、催化剂含量、原料物质的量比等对HZSM-5分子筛催化环已烯水合反应的影响.得到较佳的反应条件为搅拌速度360 r/min,反应时间4h,反应温度405 K,反应...     

La修饰ZSM-5分子筛催化剂用于C4烯烃催化裂解制丙烯

采用不同含量的La对ZSM-5分子筛进行改性，考察其在C₄烯烃催化裂解制丙烯反应中的催化性能。结果发现，少量La的引入不会破坏分子筛催化剂的骨架结构，改性后催化剂活性的变化是由于其表面酸性的改变而引起。分子筛催化剂表面酸量决定其C₄烯烃裂解反应活性，La的加入使催化剂表面酸量减少，从而使烯烃转化率降低。催化剂表面酸强度是影响其产物分布的主要因素，酸性越强，催化剂裂解能力越强，产物丙烯的选择性也就越高。尽可能提高催化剂表面强酸的酸量是C₄烯烃催化裂解制丙烯反应催化剂的研制方向。     

二甲醚催化氧化制下游化学品(Ⅰ)HZSM-5催化氧化制碳氢化合物

考察了4种分子筛HZSM-5、Hβ、HY、Al-MCM-41及Mn、Mo、Co、Cu改性的HZSM-5型分子筛催化剂对二甲醚（DME）催化氧化制碳氢化合物的反应性能。结果表明，HZSM-5分子筛在275～325 ℃具有较高活性；二甲醚的转化率在Mn改性的HZSM-5分子筛催化剂上有较大提高，275 ℃时达到27. 8 %，甲酸甲脂（MF）的收率可达6. 9 ％。并在生成产物的基础上推测了二甲醚催化氧化的反应机理。     

Efficient catalytic epoxidation of olefins with hierarchical mesoporous TS-1 using TBHP as an oxidant

A series of hierarchical mesoporous TS-1 zeolites with MFI structure were successfully synthesized via hydrothermal route using amphiphilic organosilanes as pore directing templates. These materials were characterized by nitrogen sorption (for surface area, pore volume and pore size distribution), FTIR, SEM and UV–Visible spectroscopy. These materials are efficient catalysts for liquid phase epoxidation of olefins using TBHP as the oxidant. All these TS-1 samples oxidized cyclohexene selectively into epoxide. For the TS-1 sample with 4.4 % Ti complete conversion of cyclohexene into epoxide was observed.     

Synthesis, characterization of high Ti-containing Ti-MCM-41 catalysts and their activity evaluation in oxidation of cyclohexene and epoxidation of higher olefins

A series of titanium rich isomorphous substituted Ti MCM-41 and HMS materials have been synthesized with different Si/Ti ratios. The highest amount of Ti incorporated in synthesis gel is in TiMCM-41 (Si/Ti = 10). Whereas for TiHMS catalysts, Ti is incorporated up to Si/Ti = 50 successfully without forming any extra framework TiO₂. Cyclohexene epoxidation reaction with dry tert-butyl hydroperoxide (TBHP) as an oxidant has been studied to evaluate the catalytic properties of Ti substituted mesoporous catalysts. The effect of molar ratio of substrate:oxidant in this reaction has been studied and high conversion, high selectivity were achieved at 2: 1 molar ratio with TiMCM-41 (Si/Ti =25). Dry TBHP (in dichloromethane) and chloroform were found as good oxidant and solvent system for this reaction. Pure siliceous mesoporous silica and low `Ti' substituted mesoporous silicas were found to be efficient catalysts for oxidation of cyclohexene. An interesting variation of the selectivity from allylic oxidation to epoxidation during oxidation of cyclohexene was observed with an increase in the Ti amount in the mesoporous framework. The allylic oxidation of cyclohexene has been carried out using molecular oxygen as an oxidant and in the presence of a small amount of TBHP as initiator. Siliceous HMS materials gave better conversion compared to MCM-41 type of materials and other conventional silicas like silica gel, fumed silica etc. in allylic oxidation of cyclohexene. Epoxidation of higher cyclic olefins like cyclooctene, cyclododecene, cis-cyclododecene and linear olefins 1-Heptene, cis-2-hexene, 1-undecene was carried out over TiMCM-41 (Si/Ti = 25). Ti substituted mesoporous catalysts were characterized by elemental analysis, XRD, FTIR, UVDRS, ²⁹SiMASNMR, BET surface area and pore size distribution techniques.     

Epoxidation of n-hexene and cyclohexene over titanium-containing catalysts

TS-1, Ti-beta and Ti-MCM-41 molecular sieves have been prepared by direct hydrothermal synthesis method and applied to the epoxidation of n-hexene and cyclohexene with H₂O₂ under mild conditions. Ti-beta with extremely low Al content was synthesized by using a seed method to suppress the formation of diol produced by Brønsted acid sites present in Ti-beta. It was also found that a large amount of by-products (1-ol and 1-one) formed over hydrophilic Ti-MCM-41. We further modified Ti-MCM-41 by silylation with bis(trimethylsilyl) trifluoroacetamide (BSTFA). Among these catalysts, the Ti-beta with low content of Al enhanced the yield of epoxide and suppressed the formation of diol markedly. The silylated Ti-MCM-41 reduced the formation of by-products and promoted the yields of epoxide significantly. Based on experimental results, a reaction mechanism with two parallel and competitive reactions was proposed.     

The Influence of Surface Modification on the Epoxidation Selectivity and Mechanism of TiSBA15 and TaSBA15 Catalysts with Aqueous Hydrogen Peroxide

The thermolytic molecular precursor method was used to introduce site-isolated Ti(IV) and Ta(V) centers onto the surface of a mesoporous SBA15 support. The resulting surface SiOH, TiOH, and TaOH sites were modified with a series of (N,N-dimethylamino)trialkylsilanes, Me₂NSiMe₂R (where R = Me, ⁿ Bu, or ⁿ Oc). Compared to the unmodified catalysts, the surface-modified catalysts are more active in the epoxidation of cyclohexene with H₂O₂ and exhibit a markedly greater selectivity for cyclohexene oxide (up to 58% for Ti(IV) and greater than 95% for Ta(V)). In situ spectroscopies were used to probe this phenomenon, and it was determined that a siloxy-capped Ti(IV) or Ta(V) site is essential to achieve the high epoxide selectivity.     

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%.     

钼基催化剂在烯烃液相环氧化反应中的应用研究进展

介绍了钼络合物催化剂、固载化的钼络合物催化剂及MoO₃基的固体钼催化剂在烯烃液相环氧化反应中的应用。以有机过氧化物为氧化剂时,不同的钼基催化剂均表现出很好的催化性能,其中络合物中的配体对其催化性能有很大影响,并且可以通过引入手性配体实现对烯烃的不对称环氧化,而固体钼催化剂的性能则与载体上钼物种的种类密切相关。但绝大多数钼催化剂对H₂O₂参与的环氧化反应没有活性,开发对H₂O₂有催化活性的钼基催化剂是一个重要的研究方向。     

PS负载acac系列钼配合物的合成、表征及其催化性能

以二乙烯苯交联的大孔聚苯乙烯树脂(PS)为载体,首次制备了高分子配体PS-(OCH2CH2)n-acac(n=0,1,2),并在其上组装入了Mo活性中心而成为催化剂--PS-(OCH2CH2)n-acac-Mo(n=0,1,2);用红外光谱分别对高分子配体及催化剂的结构进行了表征.XPS表征证实催化剂中钼以Mo(Ⅵ)价态存在,此外还对催化剂可能存在的结构进行了分析.实验检测了PS-(OCH2CH2)n-acac-Mo (n=0,1,2)在以n(t-BuOOH)=0.1 mol计,n( (◇)):n(t-BuOOH)=3:1,溶剂用量～10 mL,反应温度～80℃,时间～60 min条件下的催化性能.结果表明,在大孔PS载体上,活性组分与载体间增加2个-(OCH2CH2)-距离的臂长,对催化剂催化性能无明显影响;PS-(OCH2CH2)n-acac-Mo催化剂(n=0,1,2)催化环己烯环氧化活性和选择性优异,其中以PS-acac-Mo催化剂最优,环氧环己烷收率在99.5%以上.用于环己烯环氧化反应经循环使用5次后,t-BuOOH转化率仍高达99%以上,催化选择性并未发现明显减低,仍保持在99%以上.     

Optimisation of olefin epoxidation catalysts with the application of high-throughput and genetic algorithms assisted by artificial neural networks (softcomputing techniques)

An olefin epoxidation Ti catalyst has been optimised by means of high-throughput experimentation involving materials synthesis, postsynthesis treatments, and catalytic testing. Softcomputing techniques for advanced experimental design have been used. The variables explored in the hydrothermal synthesis of Ti-silicate-based catalysts were: concentration of OH⁻, titanium, and surfactant. The probe reaction employed for the optimisation was the solvent-free epoxidation of cyclohexene, with tert-butylhydroperoxide as oxidant. The different catalyst groups detected by clustering analysis were studied by XRD and UV diffuse reflectance. Ti-mesoporous MCM-41 and MCM-48 molecular sieves were among the most active catalysts. The best performing catalysts were tested for epoxidation of different linear olefins.     

Ionic Manganese Porphyrins with S-containing Counter Anions: Mimicking Cytochrome P450 Activity for Alkene Epoxidation

The ionic manganese porphyrins, composed of trimethylbenzylammonium cations and S-containing anions, were designed to mimic cytochrome P450. S-containing anions could function as the stoichiometric axial ligands and counterions dually. Such ionic catalysts showed good catalytic performance in alkene epoxidation as compared with their neutral counterparts, in terms of activity, epoxide selectivity, and recyclability.     

Co2 +-exchanged SAPO-5 and SAPO-34 as efficient heterogeneous catalysts for aerobic epoxidation of alkenes

Co-SAPO-5 and Co-SAPO-34 were prepared by a simple ion-exchange route and firstly applied in the aerobic epoxidation of alkenes. Both catalysts exhibited high activities in the epoxidation of alkenes with air to achieve 92.0–91.9 mol% conversion with the epoxide selectivity of 89.5–90.5% for styrene, 71.6–80.0 mol% conversion with 94.8–95.0% selectivity for α-pinene, and 95.3–96.8 mol% conversion with 75.2–73.6% selectivity for α-methyl styrene. Recycling studies and control experiments showed the recyclability and stability of Co-SAPO-5 and Co-SAPO-34 as heterogeneous catalysts.