Greening of alkene epoxidations via use of polymer-supported Mo(VI) catalysts in a continuous reactive distillation process

烯烃是第一代从石油中大规模提取的基本有机化学物质。这些分子本身被转化为广泛的第二代有机化学构建块，可以进一步进行化学修饰，为制药和农化工业以及家庭和个人产品工业等行业提供丰富的前体有机分子。环氧化物是第二代有机化学基石中具有重要战略意义的一类，该提案涉及一种新的更环保的化学技术，将烯烃转化为环氧化物。目前，这是在小规模和大规模上进行的，使用可溶性（均相）金属催化剂，例如钼配合物，化学反应所需的氧气由一种特定的氧化剂，烷基过氧化氢提供。后者在反应过程中转化为酒精分子，这很容易再循环到过氧化氢中，也就是说，这部分过程非常环保。然而，不幸的是，在环氧化反应中使用可溶性催化剂需要一个复杂的化工厂，包括一个大型间歇式反应器，一个大量的下游产品分离和净化装置，以及一个回收从反应器中逸出的任何可溶性催化剂的附加过程。这个复杂的工厂建造成本很高，能源和材料（例如冷却水）效率很低，也就是说，它绝不像它可能的那样环保。目前的项目旨在通过将催化剂固定在小聚合物（塑料）颗粒的多孔结构内，将通常的可溶性催化剂转化为不溶性（非均相）催化剂。这将使催化剂更容易处理和有效地保留，即。传统装置的催化剂回收部分是多余的。催化剂的颗粒形式也允许它被包装在一个中空的金属柱中，后者将被用作发生烯烃到环氧化物化学转化的反应器。其简单之处在于烯烃和氧化剂可以连续地流过不溶性催化剂的床层，而不发生任何催化剂的泄漏或损失。在进一步的技术改进中，反应器塔还将用于从副产物醇中分离有用的环氧化物产物，以及从反应中形成的任何痕量不需要的副产物中分离出来，即下游产物分离和净化装置也将是多余的。因此，总的来说，该项目将产生一种基于不溶性催化剂的新的综合化学技术，并消除与当前工艺技术相关的大部分工厂。新技术的简单性意味着整体能源和材料需求将大大减少，而且任何这种新工艺的成本都比目前的工艺低得多。因此，该项目将对改善烯烃环氧化工艺的环境性能作出重大贡献。

Alkenes are first generation fundamental organic chemical building blocks derived on a large scale from oil. These molecules are themselves converted into a wide range of second generation organic chemical building blocks which can be further chemically modified to provide a wealth of precursor organic molecules for the pharmaceutical and agrochemical, industries, and also for industries such as the household and personal products industries. One strategically important class of second generation organic chemical building blocks are the epoxides, and this proposal relates to a novel more environmentally friendly chemical technology for converting alkenes into epoxides. Currently this is carried out on both a small and large scale using soluble (homogeneous) metal catalysts e.g. molybenum complexes, with the oxygen required for the chemical reaction being provided by a specific oxidant, an alkyl hydroperoxide. The latter is converted to an alcohol molecule in the course of the reaction and this is easily recycled back to the hydroperoxide i.e. this part of the process is really quite environmentally friendly. Unfortunately however use of a soluble catalyst in the epoxidation reaction requires a complex chemical plant involving a large batch reactor, a substantial downstream product isolation and purification plant, and an additional process to recover any soluble catalyst that escapes from the reactor. This complex plant is costly to build and is very energy and materials (e.g. cooling water) inefficient i.e. it is by no means as environmental friendly as it might be.The present project aims to convert the usual soluble catalyst into an insoluble (heterogeneous) one by immobilising the catalyst inside the porous structure of small polymer (plastic) particles. This will allow the catalyst to be more easily handled and retained efficiently, ie. the catalyst recovery part of a conventional plant will be redundant. The particulate form of the catalyst will also allow it to be packed inside a hollow metal column, and the latter will be used as the reactor in which the chemical conversion of alkene to epoxide will take place. The simplicity of this is that the alkene and the oxidant can be flowed through the bed of insoluble catalyst in a continuous way without any leakage or loss of catalyst. In a further technology improvement the reactor column will also be utilised to separate the useful epoxide product from the by-product alcohol, and also from any traces unwanted sideproducts that are formed in the reaction, i.e. the downstream product isolation and purification plant will also be redundant. Overall therefore the project will give rise to a new integrated chemical technology, based on an insoluble catalyst, and eliminating a substantial part of the plant associated with the current process technology. The very simplicity of the new technology means that overall energy and materials demands will be reduced considerably, as well as the cost of any such a new process being much lower than that of a current process. The project will therefore make a substantial contribution to improving the environmental performance of alkene epoxidation processes.