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

烯烃是第一代基本有机化学结构单元，其大规模衍生自石油。这些分子本身被转化为广泛的第二代有机化学结构单元，其可以进一步化学改性以提供用于制药和农用化学品工业以及诸如家用和个人产品工业的大量前体有机分子。一类具有战略重要性的第二代有机化学结构单元是环氧化物，并且该提议涉及用于将烯烃转化为环氧化物的新型更环境友好的化学技术。目前，这在小规模和大规模上使用可溶性（均相）金属催化剂（例如异丙基苯铵络合物）进行，其中化学反应所需的氧由特定氧化剂（烷基过氧化氢）提供。后者在反应过程中转化为醇分子，这很容易再循环回氢过氧化物，即该过程的这一部分确实非常环保。然而，不幸的是，在环氧化反应中使用可溶性催化剂需要复杂的化工设备，包括大型间歇式反应器、大量下游产物分离和纯化设备以及回收从反应器中逸出的任何可溶性催化剂的附加工艺。这种复杂的装置建造成本高，能源和材料（如冷却水）效率低，也就是说，它绝不是环境友好型的。本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保留，即。常规装置的催化剂回收部分将是多余的。催化剂的颗粒形式还将允许其填充在中空金属柱内，并且后者将用作反应器，在该反应器中将发生烯烃向环氧化物的化学转化。其简单性在于烯烃和氧化剂可以以连续的方式流过不溶性催化剂床而没有任何催化剂的泄漏或损失。在进一步的技术改进中，反应器塔还将用于将有用的环氧化物产物与副产物醇分离，并且还与反应中形成的任何痕量的不需要的副产物分离，即下游产物分离和纯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工厂的很大一部分。新技术的简单性意味着总的能源和材料需求将大大减少，并且任何这种新工艺的成本远低于当前工艺的成本。因此，该项目将为改善烯烃环氧化工艺的环境性能做出重大贡献。

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.