【作者】 魏珺芳；

【导师】 王延吉；

【作者基本信息】 河北工业大学 ， 化学工艺， 2011， 博士

【摘要】 环己醇是一种重要的饱和脂环醇,它是生产己内酰胺和己二酸的重要中间体。传统的环己醇工业生产工艺循环量大,能耗高,收率低。20世纪80年代,日本旭化成公司开发了以苯为原料,经选择加氢生成环己烯,再由环己烯水合制得环己醇的两步反应工艺。本文通过设计开发一类具有新颖结构的高效双功能纳微尺度复合催化剂,将苯选择加氢制环己烯及其进一步水合制环己醇两步催化反应过程集成在同一催化剂颗粒中进行,进而构建合成环己醇反应过程的纳微尺度绿色集成系统,为开发清洁、短流程的合成环己醇先进工艺提供技术基础。制备了一系列Ru-Zn/SiO₂催化剂用于催化苯选择加氢反应,考察了催化剂载体粒径对苯选择加氢反应性能的影响;结合孔径分布及比表面积表征,分析了载体孔结构对催化剂催化性能的影响;对比了不同制备方法所制催化剂的催化性能。考察了离子液体对Ru-Zn催化苯选择加氢反应性能的影响。离子液体对Ru-Zn催化剂有良好的分散作用,可取代传统ZrO₂分散剂,减少分散剂用量的同时可使Ru-Zn催化剂回收变得简单。采用化学还原法制备了一种新型准均相纳米Ru/[Bmim]BF₄催化剂用于催化苯选择加氢反应。发现[Bmim]BF₄在化学还原过程中不仅起到了保护剂及稳定剂的作用,同时作为修饰层修饰在Ru离子表面,阻止其团聚长大;考察了Ru负载量对Ru/[BMim]BF₄催化剂催化性能的影响;对比了不同还原剂加入方式对纳米Ru形貌的影响。对硫酸催化环己烯间接水合工艺进行了考察,优化了反应工艺。考察了有机溶剂对杂多酸催化环己烯水合反应性能的影响,以正交实验的方式优化了丙酮为有机溶剂时,磷钨酸催化环己烯水合反应的工艺条件。考察了HZSM-5硅铝比对环己烯水合反应性能的影响,确定了最佳分子筛硅铝比为25;结合酸性表征推测强B酸中心是环己烯水合反应中心;优化了HZSM-5分子筛催化环己烯水合的工艺条件,适宜条件下,环己烯转化率可达11.8%,环己醇选择性为98.7%。对有机溶剂存在时,HZSM-5分子筛催化环己烯水合的工艺条件进行了优化,适宜条件下,环己烯转化率可达34.5%,环己醇的选择性为99.3%,环己醇收率较文献报道值高出约10.0%。采用多种模板剂合成了ZSM-5分子筛,重点考察了以TPAOH为模板剂、TEOS为硅源、Al（NO₃）₃为铝源,动态水热合成HZSM-5分子筛时,pH调节剂、硅铝比、晶化温度以及表面活性剂等因素对HZSM-5形貌和粒径的影响;合成了一种单分散圆饼状HZSM-5分子筛,由于其粒径小,可为环己烯水合反应提供更多的活性中心,在环己烯水合反应中可获得12.3%的环己醇收率。以单分散圆饼状HZSM-5分子筛为晶种,采用原位水热合成法、超声波预涂晶种法以及自组装预涂晶种法,在不规整载体表面合成了HZSM-5分子筛膜,对比了不同方法合成分子筛膜的差别。制备了以Ru-Zn或Ru-Zn/SiO₂催化剂为核,HZSM-5膜为壳的纳微尺度复合催化剂,并在此基础上构建了纳米尺度苯选择加氢与环己烯水合绿色集成系统。提出了一种脉冲加氢的动态操作方式,解决了苯选择加氢与环己烯水合反应时间不匹配的问题。以机械混合的Ru-Zn+HZSM-5分子筛为催化剂,构建了微米尺度苯选择加氢与环己烯水合绿色集成系统,并考察了工艺条件对集成反应性能的影响,在适宜条件下,可获得18.1%的环己烯收率和1.9%的环己醇收率。考察了苯选择加氢与环己烯水合反应之间存在的交互影响,发现HZSM-5的引入会导致苯选择加氢体系产生严重氢溢流,使苯加氢速率变快,苯转化率增大,环己烯选择性降低;溢流效应与HZSM-5分子筛表面酸中心数量及晶粒大小有密切关系;在环己烯水合反应中,Zn²⁺的引入可导致HZSM-5强酸中心减少,表面B酸中心减弱,水合性能下降;在HZSM-5表面,苯及环己烷与环己烯产生竞争吸附,导致环己烯与HZSM-5接触几率降低,环己烯转化率下降。更多还原

【Abstract】 Cyclohexanol is an important industrial intermediate used to produce adipic acid and caprolactam. Traditional process for producing cyclohexanol suffers from several drawbacks such as extremely large recycles, high energy consumption, poor selectivity and explosion hazards. In the 1980s, Asahi developed a commercial process for cyclohexene hydration. In this process, cyclohexene was produced through selective hydrogenation of benzene. In this paper, a novel nano-microscale catalyst with high efficiency and multi-function was designed and developed for the integration of selective hydrogenation of benzene and hydration of cyclohexene. A green integrated system for synthesizing cyclohexanol was established on this catalyst. It provided the technical basis for developing a clean and short process for synthesizing cyclohexanol.A series of Ru-Zn/SiO₂ catalysts were prepared for selective hydrogenation of benzene. The effects of particle size and pore structure of the supports on the catalytic activity were studied. The catalytic performance of the catalysts prepared by different methods was compared.The effect of ILs on the activity of benzene selective hydrogenation was studied. ILs could replace ZrO₂ as dispersant, and simplify the recovery of Ru-Zn.A new quasi-homogeneous catalyst, nano-Ru/[Bmim][BF₄] was developed by chemical reduction method. It was proved that the ionic liquid served not only as the protective agent or stabilizing agent to inhibit the aggregation of Ru nanoparticles, but also modification agent adsorbed on the Ru nanoparticles. The effect of Ru loading on catalytic performance of Ru/[Bmim][BF₄] was examined. The morphology of nano-Ru prepared by different dropping sequences was characterized.The indirect hydration of cyclohexene catalyzed by sulfuric acid was studied. The reaction conditions were optimized. The effect of organic solvents on the activity of cyclohexene hydration catalyzed by phosphorus acid was studied. The reaction conditions were optimized by orthogonal experiments with acetone as solvent. The effect of SiO₂/Al₂O₃ ratio of HZSM-5 zeolite on cyclohexene hydration was investigated. The optimum SiO₂/Al₂O₃ ratio of HZSM-5 zeolite was 25. It was proved by acidic characterization that the strong Br?nsted acid sites were the active sites of cyclohexene hydration. Under the optimum conditions, the highest cyclohexene conversion was 11.8% with 98.7% cyclohexanol selectivity. Effect of different kinds of organic solvents on cyclohexene hydration was studied, and the optimal organic solvent was selected. The reaction conditions of cyclohexene hydration with solvents were optimized. Under the most suitable conditions, the highest cyclohexene conversion was 34.5%, the cyclohexanol selectivity was 99.3%.HZSM-5 zeolite was synthesized using various templates. HZSM-5 zeolite synthesized using aluminum nitrate （Al（NO₃）₃）, tetraethyl orthosilicate （TEOS）, and tetrapropyl ammonium hydroxide （TPAOH） as raw materials was mainly studied. The effects of pH regulators, SiO₂/Al₂O₃ ratio, crystallization temperature and surfactants on morphology and particle size of HZSM-5 zeolite were investigated. Because the HZSM-5 zeolite with regular morphology and small particle size could provide more active sites in cyclohexene hydration, it could obtain cyclohexanol 12.3% yield. On the basis of HZSM-5 zeolite synthesis, HZSM-5 zeolite membranes were synthesized on irregular supports by in situ hydrothermal synthesis method, pre-seeding method and self-assembly seeding method. The differences of these HZSM-5 zeolite membranes synthesized by different methods were studied.A new multi-functional composite catalyst for the integration reaction was prepared with Ru-Zn catalyst or Ru-Zn/SiO₂ catalyst as core, HZSM-5 zeolite membrane as shell. The green integrated system of benzene selective hydrogenation and cyclohexene hydration in nano-scale was established on the Ru-Zn@HZSM-5 and Ru-Zn/SiO₂@HZSM-5 catalysts. The green integrated system of benzene selective hydrogenation and cyclohexene hydration in micro-scale was established on the mechanical mixed Ru-Zn+HZSM-5 catalyst. A dynamic operation by pulsed hydrogenation for the integration reaction was investigated to deal with the mismatch of reaction time. The reaction conditions of the integrated reaction were optimized. Under the most suitable conditions, the yield of cyclohexene and cyclohexanol was 18.1% and 1.9% respectively.The interaction between benzene selective hydrogenation and cyclohexene hydration was studied. The addition of HZSM-5 resulted in high conversion of benzene and low selectivity of cyclohexene. It was thought to be the result of the effect of hydrogen spillover which was closely related to the number of acid sites and particle size of HZSM-5 zeolite. The addition of ZnSO4 resulted in decreasing of cyclohexene conversion and cyclohexanol yield. It was found that the existence of Zn2+ on the surface of HZSM-5 resulted in decreasing of B acid. The competitive adsorption of benzene, cyclohexane and cyclohexene on the suface of HZSM-5 resulted in cyclohexene conversion decreasing.更多还原