以哌啶为模板剂合成FER分子筛及其催化应用（英文）

发布时间：2018-02-15 11:13

本文关键词： FER分子筛哌啶晶化过程 MWW分子筛骨架异构化　出处：《催化学报》2017年11期 　论文类型：期刊论文

【摘要】：镁碱沸石(FER结构)是一种中孔沸石,具有垂直交叉的二维孔道系统.其一为沿[010]方向的八元环孔道(0.35 nm×0.48 nm),另一为沿[001]方向的十元环孔道(0.42 nm×0.54 nm).FER分子筛是工业化的沸石催化剂之一,主要应用于1-丁烯骨架异构化反应.此外,FER分子筛在氮氧化物分解和还原、二甲醚羰基化、甲醇制烯烃、烷烃加氢异构以及正构烷烃裂化等反应中也表现出极大的应用价值.FER分子筛通常在有机模板剂的辅助下合成.常用的有机模板剂主要为有机胺化合物,包括乙二胺、吡咯烷、吡啶和环己胺等化合物.四氢呋喃等含氧化合物也可以用于导向FER分子筛的合成.此外,通过两种不同尺寸的有机分子进行组合,也可以导向合成FER分子筛,且这些分子筛往往具有独特的物化性质和催化性能.以哌啶和四甲基氢氧化铵为组合模板剂,可以得到多级孔FER分子筛.与粒径较大的FER分子筛相比,其在低密度聚乙烯催化裂解反应中表现出更为优异的催化性能.以吡咯烷和有机硅烷为组合模板剂,可以得到多级孔FER纳米片团簇.与传统的微米FER分子筛相比,该多级孔FER纳米片团簇在甲苯与苄氯的苄基化反应中的催化活性得到显著提高.最近,有研究者以1,6-双(N-甲基吡咯烷)己烷和四甲基铵离子为组合,同样得到了FER分子筛.本文以哌啶为有机模板剂合成了FER分子筛,详细考察了合成参数(碱度、水含量)和晶化条件(晶化温度、晶化时间)对FER分子筛合成的影响.结果表明,温度对FER分子筛的晶化过程影响比较大.在150?C晶化时,只有FER分子筛出现在其晶化过程中;在160或170?C晶化时,其晶化过程伴随有MWW分子筛的生成和消失.高温有利于FER分子筛的晶化,但其易于转化为其它杂相.凝胶硅铝比为40.0时,合成纯相FER分子筛的碱度比较高;而凝胶硅铝比为30.3时,合成纯相FER分子筛的碱度比较低.在低碱度晶化时,不同硅铝比的凝胶出现的杂相也不尽相同.凝胶硅铝比为40.0时,其产物为FER分子筛与MTN分子筛的混合物;而凝胶硅铝比为36.4时,其产物为MWW分子筛与MTN分子筛的混合物.水含量对FER分子筛的合成影响也比较大.当水含量较低时,其产物容易出现其它杂相;当水含量较高时,其产物为无定形物质.通过向高水含量的体系中添加FER晶种,可以得到高结晶度的FER分子筛.FER分子筛的化学组成、形貌和织构性质与初始凝胶的碱度密切相关.初始凝胶碱度较低时,产物的硅铝比较高,外表面积较大,一次粒子粒径较大且堆积疏松;初始凝胶碱度较高时,产物的硅铝比较低,外表面积较小,一次粒子较小且堆积紧密.此外,以哌啶为模板剂合成的FER分子筛在1-丁烯骨架异构化反应中表现出优异的催化稳定性和较高的异丁烯收率.
[Abstract]:Magnesia-alkali zeolite (fer) is a mesoporous zeolite. A 2-D channel system with vertical crossover. One is an octa-ring channel with 0.35 nm 脳 0.48 nm in the direction of [010], the other is a 10-member ring channel with 0.42 nm 脳 0.54 nm).FER molecular sieve along the direction of [001], which is one of the industrial zeolites. It is mainly used in the isomerization of 1-butene framework. In addition, the molecular sieve of Fer is decomposed and reduced in nitrogen oxides, carbonylation of dimethyl ether, methanol to olefin. The hydroisomerization of alkanes and the cracking of n-alkanes also show great application value. Fer molecular sieve is usually synthesized with the aid of organic templates. The main organic templates are organic amine compounds, including ethylenediamine, pyrrolidine, pyrrolidine, and so on. Compounds such as pyridine and cyclohexylamine. Oxygen compounds such as tetrahydrofuran can also be used for the synthesis of FER molecular sieves. In addition, FER molecular sieves can also be synthesized by combining two organic molecules of different sizes. These molecular sieves often have unique physicochemical properties and catalytic properties. Using piperidine and tetramethylammonium hydroxide as combined templates, multiporous FER molecular sieves can be obtained. With pyrrolidine and organosilane as the combined template, multiporous FER nanoclusters can be obtained. Compared with the traditional micron FER molecular sieve, it has better catalytic performance in the catalytic cracking reaction of low density polyethylene (LDPE). The catalytic activity of the multiporous FER nanoclusters in benzylation of toluene with benzyl chloride was significantly improved. In this paper, FER molecular sieve was synthesized with piperidine as an organic template. The synthesis parameters (basicity, water content) and crystallization conditions (crystallization temperature) were investigated in detail. The effect of crystallization time on the synthesis of FER molecular sieve. The results show that the temperature has a great effect on the crystallization process of FER molecular sieve. During C crystallization, only FER zeolites appear in the crystallization process, and in 160 or 170? The crystallization process of C was accompanied by the formation and disappearance of MWW molecular sieve. The high temperature was favorable to the crystallization of FER molecular sieve, but it was easy to be transformed into other heterogenous phases. When the ratio of gel, silicon and aluminum was 40.0, the basicity of pure FER molecular sieve was relatively high. However, when the ratio of silica to aluminum is 30.3, the basicity of pure phase FER molecular sieve is relatively low, and the heterogeneity of gel with different ratio of Si to Al is different when the ratio of Si to Al is 40. 0, and the ratio of Si to Al is 40. 0 when the ratio of Si to Al is 30. 3. The product is the mixture of FER molecular sieve and MTN molecular sieve, and when the ratio of silica to aluminum is 36.4, the product is the mixture of MWW molecular sieve and MTN molecular sieve. The effect of water content on the synthesis of FER molecular sieve is also great. When the water content is high, the product is amorphous. The chemical composition of FER molecular sieve 路fer molecular sieve with high crystallinity can be obtained by adding FER crystal seed to the system with high water content. The morphology and texture properties are closely related to the basicity of the initial gel. When the basicity of the initial gel is low, the silicon and aluminum content of the product is higher, the surface area is larger, the particle size is larger and the initial gel is loose, and when the initial gel basicity is high, The product is relatively low in silicon and aluminum, smaller in surface area, smaller in primary particle size and compact in stacking. FER molecular sieve synthesized with piperidine as template showed excellent catalytic stability and high yield of isobutene in the isomerization of 1-butene.
【作者单位】：中国科学院大连化学物理研究所;中国科学院大学;南京荣欣化工有限公司;
【基金】：supported by the National Natural Science Foundation of China(21376235) Natural Science Foundation of Liaoning Province(201602740)~~
【分类号】：O643.36

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