Catalytic Upgrading of Polymer Waste into Value-Added Products

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Plastics have played an instrument role in the development of modern day society, but growing environmental concerns associated with the industry has created an appetite for renewable alternatives. Indeed, it is clear the development of alternative waste management strategies is necessary to compliment the introduction of bio-based and biodegradable plastics as the industry shifts from a linear to circular economy. Thus, this project aims to:- Investigate catalytic upgrading (via chemical recycling) of commercially bio-based plastics (e.g. PLA) into value-added products, such as lactate esters or acrylic acid, which have been cited as potential green substitutes for traditional petrochemical based solvents/chemicals. Key aspects to this process include:Development of novel, industrially viable catalysts (i.e. using cheap/abundant metals and scalable ligands systems).- High selectivity and yield under mild conditions, with metal-mediated degradation examples remaining limited. Indeed, current recycling methods rely on harsh reaction conditions, are resource/energy intensive and lead to eventual material 'downcycling' in the case of mechanical recycling 1 Chemical recycling has the potential to address these concerns. - Demonstrate process scalability on a novel spinning disc reactor, adopting an interdisciplinary approach to research by working at the boundary between chemistry and engineering.- Extend established methodologies to other commercially relevant polyesters, including PET and PEF, but also other polymer classes: polycarbonates, polyamides etc.- Immobilize developed catalysts on a support to overcome industry concerns associated with catalyst recovery, a limiting feature of homogeneous catalysts. This will also assist in upscaling the established recycling technology. Additionally, all novel catalysts prepared will also be investigated for their activity in the ROP of rac-LA in both solution and under industrially preferred melt conditions for PLA production and for polycarbonate formation (CO2/epoxide or anhydride/epoxide). Polymer of interest will be characterised using standard thermal/mechanical characterisation techniques.Project strategy:1. Preparation of scalable ligands, for example Schiff-Base.2. Complexation to broad range of earth abundant metals e.g. Group (I), Group (II) and Zn.3. Catalytic testing (batch and in flow).4. Evaluate catalytic data to determine structural-activity relationships to understand catalytic upgrading processes through experimental and computational modelling.5. Develop catalytic reactor to scale up the degradation and to prepare value-added products from waste materials. References:1. J. Payne, P. McKeown and M. D. Jones, Polym. Degrad. Stab., 2019, 165, 170-181.