Acidic Ionic Liquids as Catalysts for the Valorisation of Waste Plastic Resources

The mass production of plastic in our society is a huge problem while it has transformed civilisation and allowed the construction of high-performance devices and materials, it has also brought an abundance of single use items. Public perceptions toward the impact of plastic waste have changed significantly and recycling has reduced the environmental impact. However, many areas of recycling are impractical and unfeasible, so alternative approached such as chemical recycling and repurposing are required.

In this project, chemical recycling of waste plastic feedstock will be investigated and developing a new, inexpensive acidic ionic liquid catalyst that are robust and capable to deal with contaminated feedstocks. This will overcome a major technical barrier to utilise wastes plastics as a chemical resource.

The aim is to use waste plastic feedstock and transform it to lubricating base oil which is used in a range automotive machine to improve efficiency. This uses waste and transforms it into a useful chemical product without exploiting natural resources. This allows the production of lubricating base oil without additional fossil fuels as there is an abundance of plastic waste.

Ionic liquids and liquid coordination complexes as Lewis acidic catalyst are used for oligomerisation of olefins that are presence in base oil. The grade of the base oil depends on the distribution of oligomers. This approach with ionic liquids and liquid coordination complexes allows the reaction mixture to take place at mild conditions and ambient pressure. This means when implemented at industrial scale the issues of using highly toxic and dangerous gases are avoided as ionic liquids have a low vapour pressure.

To achieve this, the synthesis of various ionic liquids and liquid coordination will take place and the efficiency and conversion of the catalyst will be measured when using the plastic feedstock. This process will be optimised in the hope to find a new catalyst that can be used to convert the waste plastic into a value-added chemical resource.

This project is taking place at Queen's University Ionic Liquid Laboratories which is the most established centre for ionic liquids in the world. This research will benefit society and the environment as waste plastic can be utilised into a chemical resource which has many applications. This aligns with EPSRC research areas in developing new catalysts and using synthetic coordination chemistry.