【作者】 张法智；

【导师】 王祥生；

【作者基本信息】 大连理工大学 ， 工业催化， 2000， 博士

【摘要】 钛硅分子筛TS-1是八十年代出现的一种新型分子筛，它为研究有机物催化氧化反应和开发环境友好化工工艺提供了新途径。由于经典的水热晶化合成方法存在着合成原料昂贵、反应条件苛刻等缺点，严重地阻碍了钛硅分子筛的工业化进程。气固相制备技术可以在已有的分子筛母体的基础上，从更广阔的范围内探索研究钛硅分子筛的合成，并且具有操作简单、原料廉价易得等特点，因此近年来成为钛硅分子筛制备研究的一个重要方向。研究结果表明，目前这方面的工作尚处于探索性阶段。对于母体的选择、气固相制备的影响因素以及反应机理等方面的认识还很模糊，实际操作中更难以对载钛量进行有效控制。这种研究现状必然影响到气固相制备技术的进一步发展。本论文通过系统研究不同物化性质母体的载钛效果，伴随着多种光波谱表征手段，深入探讨气固相反应机理及钛原子引入分子筛骨架的过程机制。充分利用气固相载钛调节范围大的特点，通过分子筛母体的选择及其结构性能的调变，为钛原子引入分子筛骨架创造便利条件，探索一条适宜的气固相制备工艺路线。在此基础上，提出筑窝植钛的构思来有效控制进入骨架的钛量，为提高钛硅分子筛的气固相制备水平开拓新的途径。目前，钛硅分子筛的基础理论研究工作中一般仅从骨架钛物种单一方面来分析催化反应活性中心的结构及其作用方式，因此在某些具体反应结果的讨论以及催化氧化反应机理的探讨中不能给出满意的解释。本论文结合光波谱的表征结果和丙烯环氧化反应的催化性能，从骨架四配位钛物种Ti⁴⁺和单核孤立非骨架钛物种TiO_x两方面的催化作用考虑，深入探讨了钛硅分子筛催化活性中心的本质，为钛硅分子筛催化氧化反应机理的研究和环境友好环氧丙烷生产工艺的工业应用提供理论和实验的基础数据。 大连理工大学博士学位论文 本论文选择具有不同物化性质的含铝、高硅及含硼Pentasil型分子筛作为气固相反应的母体，考察了母体的脱铝或脱硼处理对气固相载钛效果的影响：采用＊RD气＊一IR 欠＊＊朋＊气＊＊ 和＊＊＊、＊＊＊气”B＊＊s＊＊R等技术研究气固相反应前后分子筛的表面组成及结构特性，深入探讨了气固相制各钛硅分子筛的反应机理及钛原子引入分子筛骨架的过程机制；通过对气固相反应条件如反应温度、反应时间及载气N流速等影响因素的考察，获得了适宜的气固相操作条件。在以上工作的基础上，提出筑窝植钛的构思。从母体分子筛的合成着手，通过调节母体硅羟基窝kilanol nest)的浓度，有效控制进入骨架的钛含量。采用UV－Raman、UV－Vs等表征技术研究了钛硅分子筛中所含钛物种的配位状态，并结合丙烯环氧化反应性能，探讨了钛硅分子筛催化丙烯环氧化反应活性中心的本质。从工业应用及基础研究出发，在间歇釜内考察了TESM6分子筛的催化性能，研究了反应温度、反应时间、丙烯压力、双氧水及催化剂用量等操作参数的影响，确立了适宜的丙烯环氧化条仆。依据溶剂效应及酸、碱性添加物影响的实验结果，验证了nm＊6分子筛骨架钛五员环活性中间体结构假设的合理性，并推测了丙烯环氧化反应的历程。最后以脱铝的p田EA型)和M（MOR型）分子筛为母体，制备出大孔径1、p和Ti－M分子筛，并以环己烯环氧化反应做探针，考察了其催化反应性能。 从上述的系统研究工作中，获得了以下结果： 一、气固相法制备Pentasil型钛硅分子筛时，钛原子引入分子筛骨架的反应机理随分于筛母体结构特性的差异而不同：对于骨架含铝或含硼的分子筛母体，山于在气固相反应条件下骨架铝原子或者硼原子能够从分于筛中脱除，因此气固相反应时，钛原子直接取代这些杂原子进入分子筛骨架；而对于高硅或脱硼分子筛母体，其骨架中存在的硅羟基窝为钛原子的引入提供了可以利用的T原子空位，气固相反应时钛原子通过占据这些T原子空位而进 匹互 大连理工大学博士学位论文入骨架。研究结果表明，与含铝分子筛母体中的骨架铝原子相比，硼原子易于从含硼分子筛母体骨架中脱除，为钛原子的引入提供了便利的条件。采用含硼分子筛做母体，气固相反应前用酸洗脱硼处理这一制备路线是一条适宜的气固相反应工艺。这样一方面可以避开含铝分子筛中骨架酸性中心的影响，另外，母体的脱硼处理能够提供畅通的分子筛孔道和更多的反应活性位，因此有利于气固相反应的进行。 1、选择含铝丕M－5分子筛（硅铝比24．3）作为气固相法制备Ti－ZSM－5分子筛的母体。采用盐酸洗涤以及盐酸洗涤结合高温水蒸汽处理的办法，在气固相反应前对分子筛母体进行脱铝处理。实验中发现采用上述方法难以将骨架铝脱除完全。当采用 12M HCI溶液处理时，AI－ZSM－5的硅铝比由24．3升高到 42．5，脱铝度仅为 410。‘’AI MAS NMR和 FT－IR谱图显示，在气固相反应过程中有部分铝原子从AIZSM－5 ?更多还原

【Abstract】 Titanium silicalite (TS-1) is a novel type molecular sieve,appearing in the last decade. It gives new chance for the studies of the catalytic oxidizing reactions and the developing of the environment-friendly chemical engineering progress. But,the classical hydrothermal synthesis method of TS-1 has lots of defects,such as the costly raw materials,the severe reaction conditions,and so on. The industrial proceeding of the use of titanium silicalite as catalyst is hindered seriously by the synthesis of this titanium-containing material. Compared to the classic hydrothermal method,the gas-solid preparation way can be used to study the synthesis of TS-1 from more extensive field,based on the synthesized precursor. Besides,the operating conditions of the gas-solid reaction are not vigor and the raw materials are very cheap. So,study on this technique has become one of the most important directions in the field of the titanium silicalite. The results show that this part work is still on the exploratory stage. Including the effects of the gas-solid reaction conditions,the reaction mechanism is not clear to be understood. Further,the framework titanium content can not be controlled effectively by this method. The present situation seriously affects the gas-solid technique to be developed further. This paper investigates thorough the gas-solid reaction mechanism and the incorporating progress of the Ti atoms into the framework,by the systematic studies of precursors with different physicochemical property and the use of several kinds of spectroscopies. Based on these works,a new plot of the gas-solid method,"nest-constructing-titanium-planting",is produced for the first time to control effectively the titanium content incorporated into the framework. This plot opens a new route for the raise of the preparation level of the gas-solid method.According to the present theory studies,the structure and the function mode of the catalytic reaction centers are analyzed only based on the study of the framework titanium. On the contrary,the thesis investigate the nature of the catalytic reactive centers in titanium silicalites based on both the framework tetrahedral Ti4+ and the mononuclear and isolated nonframework TiOx,combining the results of the spectroscopies and the catalytic property of epoxidation of propylene.In this paper,the preparation of Pentasil type titanium-containing molecular sieves has been performed by using gas-solid reaction. The chosen precursors are three type Pentasil molecular sieves:aluminium-containing,highly siliceous and boron-containing molecular sieves. In addition,the effects of different pretreatment of precursors on preparation are also completed. XRD,FT-IR,UV-Vis,XPS and 29Si,27A1,11B MAS NMR techniques are used to characterize the surface structural properties of molecular sieves before and after the gas-solid reaction. Then the mechanism of the insertion of Ti atoms in the framework is analyzed based on these characteristic results. The suitable conditions of the gas-solid reaction are obtained through the investigation of the reaction temperature,time and the speed of the carrying gas N2.To effectively control the content of framework titanium,the amounts of silanol nests in precursors framework are regulated before the gas-solid reaction. This technique is named as "nest-constructing-titanium-planting".For the industrial application and fundamental investigation,the catalytic properties of Ti-ZSM-5 on the epoxidation of propylene with H2O2 are studied and the effects of reaction temperature,reaction time,pressure of propylene and amounts of H2O2 and catalyst are investigated either. The presure of theintermediate reactive center of framework titanium with five-mumbered cyclic structure is tested by the experiments of solvent and additive acid and base effects. Besides,the reaction mechanism is deduced from the experimental results.In addition,large pore titanium-containing (BEA type) and M (MOR type) zeolites have been prepared by using their responding dealuminat更多还原