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，从而形成否则不会迅速形成的化合物。典型的例子是氨的生产，这是一个需要铁催化的过程，或者生物燃料的生产。催化过程的改进不仅帮助化学家和工程师提高反应效率，而且还减少了废物，产生了巨大的环境影响。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，这一点尤其正确。从经济和社会的角度来看，这将是有益的，因为我们可以减少可持续燃料的成本，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催化反应和非均相催化反应。均相催化反应是指催化剂可以溶解在介质中，非均相催化反应是指催化剂不能溶解。均相催化剂有时更活跃，但它们的分离和再利用需要更多的能量和努力，而非均相催化剂则很容易通过简单的过滤从反应中去除和回收。根据活性位点（即催化反应发生的地方）的性质，它们可以进一步分为酸性、中性或碱性（碱性）。尽管与酸性催化反应相比，碱性催化反应的研究较少，但近年来，作为一种可持续和可再生的燃料来源，碱性催化反应已变得越来越有吸引力，因为它们适合于高效生产生物柴油。本课题主要研究基于本征微孔聚合物（PIMs）的新型碱性多相催化剂的设计与合成。pim是一种多孔材料，由于其聚合物结构在固体状态下填充效率低下，从而留下纳米尺寸的空隙。它们可用于广泛的应用，包括气体分离，气体储存和催化。多孔性代表了多相催化剂的一大优势，因为它迫使反应在一个紧密的环境中发生，比如一个孔的表面，迫使反应的组分更紧密地接触。由于这一优势，pim之前已经用于多相催化，但只能通过在材料中加入活性金属离子，这并不理想，因为金属的存在使它们更昂贵，更不环保。最近，我介绍了一类新的基于称为Tröger基础（TB）的pim，并为其申请了专利。他们将pim的高孔隙率与两种碱性（碱性）氮的存在结合起来。人们曾尝试将结核核嫁接到预制聚合物材料中，但这种方法会导致催化材料在从反应介质中回收过程中损失（称为浸出）。我最近报道了一种完全通过TB形成的网络（不溶性）PIM的合成，它显示出很大的多相催化潜力，特别是因为活性位点（TB）是材料的一个组成部分，而不是简单地接枝在它上面。该项目旨在合成新的TB-PIMs，用于催化生物质转化（即从废弃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。提高生物柴油的产量并不是这些新型聚合物可以应用的唯一重要反应。这些聚合物还将被测试将生物柴油合成过程中产生的副产品转化为更活跃的化合物，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是，这些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，这类材料可用于净水和从液体废物中去除有毒金属。

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.