Selective Electrophilic Substitution of Halogens into Alkyl-Aromatics using ZSM-5

使用 ZSM-5 将卤素选择性亲电取代为烷基芳族化合物

• 批准号: 9321392
• 负责人: Carl Lund
• 金额: $ 21.6万
• 依托单位: SUNY at Buffalo
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 1997-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9321392&HistoricalAwards=false
• 关键词: Selective; Electrophilic; Substitution; Halogens; into

9321392 Lund This is a study of the zeolite ZSM-5 as a catalyst for the chlorination of toluene. Of the three possible monochlorination products, p-chlorotoluene is the most valuable; in other reactions involving alkylaromatics, ZSM-5 is selective for formation of the para isomer. In this work, a form of ZSM-5 in which iron cations are present in ion-exchange positions of the zeolite is used. The first (chronologically) objective of the study is to determine whether the catalyst deactivates under reaction conditions, and if so, to measure the severity of the deactivation and determine its origin. The second objective is to probe the active site using sorption capacity and selectivity, Mossbauer spectroscopy, infrared spectroscopy of adsorbed species, transmission electron microscopy, acidity measurements, chemical analysis, ion exchange, and other techniques. Catalysts are prepared with various degrees of dehydration, location of iron, and silicon/aluminum ratios. Reactor studies are performed to measure catalytic activity and selectivity. The third objective is to develop a mechanistic microkinetic model of the reaction kinetics from steady-state and transient kinetics measurements and temperature-programmed desorption data. The performance of ZSM-5 is compared quantitatively to that of conventional Lewis-acid catalysts. Chlorinations and related aromatic substitution reactions are widely used in chemical manufacturing. They are presently done using relatively large amounts of inexpensive (and not very active) catalysts that create large amounts of solid waste that is now recognized to be an environmental problem. This work aims to replace such processes with ones that employ small amounts of more active catalysts that are relatively benign environmentally. ***

9321392 Lund这是对ZSM-5沸石作为甲苯氯化催化剂的研究。在三种可能的一氯化产物中，对氯甲苯是最有价值的；在其他涉及烷基芳烃的反应中，ZSM-5选择性地形成对位异构体。在这项工作中，使用了一种形式的ZSM-5，其中铁离子存在于沸石的离子交换位置。这项研究的第一个(按时间顺序)目标是确定催化剂是否在反应条件下失活，如果是，则测量失活的严重程度并确定其来源。第二个目标是利用吸附容量和选择性、穆斯堡尔谱、吸附物种的红外光谱、透射电子显微镜、酸度测量、化学分析、离子交换等技术来探索活性中心。制备的催化剂具有不同的脱水程度、铁的位置和硅铝比。进行了反应器研究，以测量催化活性和选择性。第三个目标是根据稳态和暂态动力学测量和程序升温脱附数据建立反应动力学的机理微观动力学模型。定量比较了ZSM-5与常规Lewis酸催化剂的性能。氯化反应及相关的芳香族取代反应在化工生产中有着广泛的应用。目前，它们是使用相对大量的廉价(和不是很活跃的)催化剂来完成的，这些催化剂产生大量固体废物，现在被认为是一个环境问题。这项工作旨在用使用少量更活跃的催化剂的工艺来取代这些工艺，这些催化剂对环境相对无害。***