Recycling of Mixed Polymer Consumer Waste to produce High Value Feedstocks to Promote the Circular Economy

Lead Research Organisation: University of Manchester
Department Name: Chem Eng and Analytical Science

Abstract

The aim is to design a continuous process capable of converting large quantities of unsorted mixed plastic waste to petrochemical refinery intermediates, such as 'synthetic diesel and naphtha'. In brief, this research will employ a hydrocracking catalyst continuously fed with mixed polymers to enable the development of a commercial demonstrator plant (scaled to 60 kte per annum). There are three key stages of this development: the optimisation of the reaction system including use of raw materials, temperature and pressure; the determination of mass and energy balances for the system from which a process flowsheet will be developed, and finally, a full analysis of the impacts of the proposed plant using commercial life cycle assessment software developed at Manchester.

This research will be of great importance on a national and global scale; in 2012 the EU was producing around 25 MT of plastic waste and only 25% of this was recycled at similar economic value (mechanically), while another 33% was sent for energy generation by burning, which is notoriously inefficient as well as a source of dioxins and other harmful emissions. Production of diesel and naphtha feedstocks by the method described above retains the inherent value of the polymers, taking a significant step towards a circular UK economy, as well as representing a significantly less energy intensive method of gasoline production than the fractional distillation of crude oil.

Publications

10 25 50

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509565/1 01/10/2016 30/09/2021
1788945 Studentship EP/N509565/1 06/09/2016 30/09/2019 Isaac Callum Campbell
 
Description New skills developed for lab group in analysis of solid polymer products including use of parallel-plate rheology and Fourier transform-rheology for the better understanding of how processing characteristics of polymers change with degradation.

New research questions have opened up regarding the coking of catalyst during the catalytic-polymer degradation process, and how it can be avoided. Investigations into metal loading catalysts are planned. Also, questions have become apparent regarding the changing properties of the polymer as it degrades, affecting the extrusion process. This is being investigated for better understanding using rheology.

More analysis has been performed on a screw extrusion system, allowing for understanding of the effects of various processing parameters on the degradation process, as well as the effects of catalyst and different atmospheres on the product slate. Information has also been developed on the use of different polymers as feedstock's including polyethylene , polypropylene and polystyrene.
Exploitation Route The findings from this project feed into a larger body of knowledge and understanding within the research group, including another PhD student working on a batch process for the polymer recycling, and a post-doc working on this and other mechanical modes of recycling. Our goal is that eventually the body of knowledge will be sufficiently broad and deep to have proof of the principle, allowing further development into a pilot plant, and in the case of the pilot plants successful development, adoption into an industrial-scale process. The outcomes of development of an economically viable route for recycling of mixed-polymer waste can have far-reaching impact for both industrial and public stakeholders.
Sectors Chemicals,Energy,Environment,Manufacturing, including Industrial Biotechology,Transport