LT: In-Situ Generation of Hazardous Reactants for Chemical Synthesis

LT：原位生成化学合成中的危险反应物

• 批准号: 9727137
• 负责人: George Roberts
• 金额: $ 5万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-10-01 至 1999-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9727137&HistoricalAwards=false
• 关键词: LT; Situ; Generation; Hazardous; Reactants

9727137 McConica The chemical industry frequently deals with hazardous chemicals by adopting alternative technologies that avoid the use of such raw materials. This is an attractive strategy, but it is not universally applicable. The alternative processes can be major generators of environmentally-harmful waste, and can involve materials that are only marginally less hazardous. Thus, other options are needed. This proposal examines a novel approach to the problem of using reactive and hazardous chemicals: in- situ generation. Successful development of this concept will create important new options in the area of environ- mentally-benign chemical synthesis. Formaldehyde is an example of a hazardous and costly chemical that has traditionally been avoided in chemical synthesis. It is a suspected or probable' man carcinogen, and it is so reactive that it cannot be stored or shipped in pure form. However, a number of important chemicals could be produced with much less pollution and with greater safety via formaldehyde than by their current commercial processes. For example, substitution of formaldehyde-based processes for the technologies currently used to produce methyl methacrylate and styrene could eliminate the use of about 8 billion pounds of benzene and about 250 million pounds of hydrogen cyanide annually, and could eliminate about 1 billion pounds of ammonium bisulfate waste and about 100 million pounds of aluminum trichloride waste annually, in the United States alone. The recent development of high-temperature slurry reactors in our laboratory, coupled with steady progress in the catalysis and reaction engineering of polystep reactions, permits a new approach to utilization of hazardous chemicals. In essence, the hazardous chemical will be generated and consumed in situ in a single reactor. For example, it is known that formaldehyde can react with methyl propionate over various heterogeneous catalysts in the temperature range of 300 to 400' C to form methyl methacrylate. It should be possible to simultaneously dehydrogenate methanol to formaldehyde in the same reactor, using a different catalyst. The coupling of these two reactions would result in the synthesis of methyl methacrylate from methanol and methyl propionate. Similarly, styrene could be synthesized from methanol and toluene. The key is to employ a slurry reactor containing a physical mixture of a methanol dehydrogenation catalyst and a catalyst for the formaldehyde-consuming reaction, with the rates of the two reactions properly balanced. This research will focus on in-situ formaldehyde generation, i.e., the dehydrogenation of methanol to formaldehyde, in a high-temperature slurry reactor. Emphasis will be placed on understanding the effect of catalyst composition and structure, and the reactor design and operating variables, on the kinetics and selectivity of the reaction. This knowledge will provide a sound fundamental basis for coupling in-situ formaldehyde generation with various formaldehyde-consuming reactions. The proposed research program has the potential to produce a major advance in environmentally-benign chemical synthesis, since the novel concept of in-situ generation should have broad applicability as an enabling technology for process substitution. The proposed research will also provide an important scientific advance, i.e., a more fundamental basis for the a priori design of catalyst systems for polystep reactions in slurry reactors. ***

9727137 McConica化学工业经常通过采用替代技术来处理危险化学品，避免使用这些原材料。 这是一个有吸引力的策略，但它并不普遍适用。 替代工艺可能是对环境有害的废物的主要产生者，并且可能涉及危险性仅略低的材料。 因此，需要其他选择。 该提案探讨了一种新的方法来解决使用活性和危险化学品的问题：原位生成。 这一概念的成功开发将在环境友好的化学合成领域创造重要的新选择。 甲醛是一种危险且昂贵的化学品，传统上在化学合成中避免使用。 它是一种疑似或可能的“人类致癌物”，而且它的反应性很强，不能以纯的形式储存或运输。 然而，许多重要的化学品可以通过甲醛生产，而不是通过目前的商业工艺生产，污染少得多，安全性更高。 例如，用基于甲酰胺的工艺替代目前用于生产甲基丙烯酸甲酯和苯乙烯的技术，每年可以消除约80亿磅苯和约2.5亿磅氰化氢的使用，并且每年可以消除约10亿磅硫酸氢铵废物和约1亿磅铝废料，仅在美国。 高温浆态床反应器的发展，以及多步反应催化和反应工程的稳步发展，为危险化学品的利用开辟了新的途径。 从本质上讲，危险化学品将在一个反应堆中就地产生和消耗。 例如，已知甲醛可以与丙酸甲酯在300 - 400 ℃的温度范围内在各种非均相催化剂上反应形成甲基丙烯酸甲酯。 应该可以在同一反应器中使用不同的催化剂同时将甲醇转化为甲醛。 这两个反应的耦合将导致由甲醇和丙酸甲酯合成甲基丙烯酸甲酯。 类似地，苯乙烯可以由甲醇和甲苯合成。 关键是使用含有甲醇脱氢催化剂和用于甲醛消耗反应的催化剂的物理混合物的淤浆反应器，其中两个反应的速率适当平衡。 这项研究将集中在原位甲醛生成，即，在高温淤浆反应器中，甲醇脱氢为甲醛。 重点将放在理解催化剂的组成和结构，反应器的设计和操作变量，对反应的动力学和选择性的影响。 这些知识将为耦合原位甲醛生成与各种甲醛消耗反应提供坚实的基础。 拟议的研究计划有可能产生一个重大的进步，在环境友好的化学合成，因为新的概念，原位生成应具有广泛的适用性，使技术的过程替代。 拟议的研究还将提供一个重要的科学进步，即，为淤浆反应器中多步反应的催化剂体系的先验设计提供了更基本的基础。 ***