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

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.

The project will generate advanced materials to be used as catalysts for commercially and environmentally important reactions.

Scientific impact: since the catalysis field is always very active, the synthesis of new materials is expected to have a great impact in the scientific community, especially if they cover a relatively unexplored area. A major aim of this proposal is also to provide direct training to a PDRA and a PhD student whose contribution is crucial for the success of the project. The scientific knowledge and experience gained will make them highly competitive in the job market.

Socio-economic impact: It is estimated that the human population will reach 9 billion people by 2050 and to keep up with the economic growth we will require 50% more fuel. At the same time, a cut of CO2 emissions by up to 80% is required to preserve political, social, fuel and climate security. The general public is well aware that the search for more efficient ways to produce sustainable fuels is extremely important, as we are rapidly exploiting the natural resources and the prices of fossil fuels can only rise. From the social point of view, this will go well beyond the mere reduction of fuel prices, as the preparation of new catalysts designed to improve pre-existing protocols will also help to reduce the amount of waste and the gas emission. It is easy to imagine that this would have a considerable environmental impact, improving the well-being and quality of life.

Industrial and economic impact: The newly implemented (15th April 2018) Renewable Transport Fuel Obligation (RTFO) compels the reduction of regular diesel use, and the doubling of biodiesel use by 2020. It is estimated that catalysis currently contribute over £50 billion/year to the UK economy. The production of better and faster catalysts will therefore be highly valued by the industrial sector, as reducing the reaction times leads to the reduction of the production costs, which is strongly beneficial for both the industry and the general public (i.e., by decreasing the prices of fuels). This project is, for that reason, likely to boost the creation of new jobs in both R&D and manufacturing.

Skills, interdisciplinary research training and public engagement: The innovative design of the proposed materials, where the basic catalytic centre is part of the polymers and not simply grafted onto a pre-existing support, not only aims to improve existing catalytic protocols, but also to spark the creativity of researchers from both industry and academia, who can try to use the same concept in their protocols, leading to further development of the field. The PDRA and PhD student involved in this project will have the chance to work in close contact with experts from other institutions, receiving state-of-the-art training that links complementary fields and allows them to expand their knowledge and skills. The renewable energy and environment-based topic of this proposal may also be of interest to the general public because of its significant impact on lifestyle and economy, for instance by showing them that our cutting-edge research will lead to a decrease of the fuel prices, and knowing that we are constantly working on tackling environmental issues such as the reduction of the use and dependence from fossil fuels. The project will use different methods for the dissemination of the obtained results, including speaking at international conferences, in public events such as Science Festivals and visiting schools, and exploiting my role of STEM Ambassador, as it is essential to teach young generations about the benefit of living in a more sustainable world.