Novel polymers of intrinsic microporosity for heterogeneous base-catalysed reactions (HBC-PIMs)

催化剂在化学中起着至关重要的作用，因为它们通过降低活化能来提高反应速度，使原本不会迅速形成的化合物得以形成。典型的例子是氨的生产，这是一个需要铁催化的过程，或者生产生物燃料。催化过程的改进不仅有助于化学家和工程师提高反应效率，而且还可以减少废物，产生巨大的环境影响。如果我们能够设计和合成新的催化剂，以更有效的方式生产替代燃料，情况就尤其如此。从经济和社会的角度来看，这将是有益的，因为我们可以降低可持续燃料的成本，同时减少对化石燃料等自然资源的开采。两种最常见的催化反应被称为均相反应和多相反应，在均相反应中，催化剂可以溶解在介质中；在多相反应中，催化剂是不溶的。均相催化剂有时活性更高，但它们的分离和重复使用需要更多的能量和精力，而多相催化剂很容易通过简单的过滤从反应中去除和回收。根据它们的活性中心的性质(即催化反应发生的位置)，它们还可以进一步分为酸性、中性或碱性(碱性)。尽管碱性催化反应比酸性催化反应更少被研究，但近年来它们变得更具吸引力，因为它们适合于高效地生产生物柴油，作为一种可持续和可再生的燃料来源。本研究项目将致力于设计和合成基于本征微孔聚合物(PIMs)的新型碱性多相催化剂。PIM是一种具有孔洞的材料，是由于其聚合物结构在固体状态下的低效率堆积而产生的，从而留下了纳米尺寸的空隙。它们可用于广泛的应用，包括气体分离、气体储存和催化。多孔性对多相催化剂来说是一个很大的优势，因为它迫使反应在封闭的环境中进行，例如孔的表面，迫使反应的组分更紧密地接触。由于这一优势，PIM以前已被用于多相催化，但仅通过在材料中加入活性金属离子来实现，这并不理想，因为金属的存在使它们更昂贵，对环境更不友好。最近，我推出了一种基于特罗格基座(Tröger‘s base，TB)的核心的新型PIM，并为其申请了专利。它们将PIM的高孔隙率与两个碱性(碱性)氮的存在结合在一起。人们试图通过将TB核嫁接到预制的聚合物材料中来使用TB核，但这一过程会导致催化材料在从反应介质中回收的过程中损失(即所谓的浸出)。我最近报道了一种专门通过Tb形成的网络(不溶性)PIM的合成，它显示了巨大的多相催化潜力，特别是因为活性中心(Tb)是材料的组成部分，而不是简单地嫁接到材料上。该项目旨在合成新的TB-PIM，用于催化生物质转化(即从废生物质转化为可持续燃料)以及其他环境和商业上重要的反应。生物柴油产量的提高并不是这些新型聚合物可以使用的唯一重要反应。还将测试这些聚合物将生物柴油合成过程中产生的副产品转化为更具活性的化合物，以及将二氧化碳转化为更有用的产品。最后但并非最不重要的一点是，这种聚合物可以进一步转化为更有效的阴离子交换树脂的新材料，这是一种可用于净水和从液体废物中去除有毒金属的材料。

Catalysts play a crucial role in chemistry, as they increase the rate of reaction by lowering the activation energy, allowing the formation of compounds that otherwise will not form promptly. Typical examples are the production of ammonia, which is a process that needs to be catalysed by iron, or the production of biofuels. The improvements of catalytic processes not only help chemists and engineers to increase the efficiency of reactions, but also to reduce waste products, generating a massive environmental impact. This is especially true if we can design and synthesise new catalysts that produce alternative fuels in a more efficient way. This will be beneficial from both the economic and the social point of view, as we can reduce the cost of sustainable fuels and, at the same time, the exploitation of natural resources such as fossil fuel. The two most common catalysed reactions are known as homogeneous, where the catalyst can be dissolved in the media, and heterogeneous, where it is insoluble. Homogeneous catalysts are sometimes more active but their separation and reutilisation requires more energy and effort, whereas the heterogeneous ones are easily removed and recycled from the reaction by simple filtration. They can be further classified as acid, neutral or basic (alkaline), according to the nature of their active sites (i.e. where the catalytic reaction happens). Although alkaline catalysed reactions have been less investigated than their acidic counterparts, in recent years they have become more attractive as they are suited for the efficient production of biodiesel, as a sustainable and renewable source of fuel. This research project will focus on the design and synthesis of novel basic heterogeneous catalysts based on Polymers of Intrinsic Microporosity (PIMs). PIMs are materials with porosity arising from the inefficient packing of their polymeric structure in the solid state, which leaves voids of nano-dimensions. They can be used for a wide range of applications, including gas separation, gas storage and catalysis. Porosity represents a great advantage for a heterogeneous catalyst, as it forces the reaction to occur in a close environment, such as the surface of a pore, forcing the components of the reaction to be in much closer contact. Because of this advantage, PIMs have been previously used in heterogeneous catalysis but only by incorporating in the material active metal ions, which is not ideal as the presence of the metal makes them more expensive and less environmentally friendly. Recently, I introduced and patented a new class of PIMs based on a core known as Tröger's base (TB). They combine the high porosity of PIMs with the presence of two basic (alkaline) nitrogens. Attempts have been made to use TB cores by grafting them into pre-made polymeric materials, but this procedure leads to loss of catalytic material (known as leaching) during its recycling from the reaction media. I recently reported the synthesis of a network (insoluble) PIM exclusively made exclusively via TB formation, which showed great potential for heterogeneous catalysis, especially because the active site (TB) is an integral part of the material, and not simply grafted onto it. The project aims to the synthesis of new TB-PIMs to be used to catalyse biomass conversion (i.e., from waste biomass to make sustainable fuels) along with other environmentally and commercially important reactions. The improved production of biodiesel is not the only significant reaction where these novel polymers can be employed. The polymers will also be tested for the conversion of by-product created during the biodiesel synthesis into more reactive compounds, and for the conversion of CO2 into more useful products. Last but not the least, the polymers can be further turned into new materials for more efficient anion-exchange resins, a class of materials that can be used for purification of water and removal toxic metal from liquid waste.