Development of an innovative microwave-based process for recycling end-of-life PVC

Halogenated plastics such as PVC are highly versatile polymers used in a wide range of applications. PVC represents ~20% of all plastics manufactured globally. However, it is their useful properties (e.g. durable, non-conductive, chemically resistant) that also mean they are particularly challenging to recycle at end-of-life. Mechanical recycling is a low-cost option, but due to degradation of material, only a limited number of recycles are possible. PVC is currently excluded from chemical recycling due to the highly corrosive acidic by-products which present a significant process engineering challenge. In addition, the range of additives and plasticisers used to modulate PVCs properties increase complexity. As a result, each year in the UK, ~460,000 tonnes of PVC-waste is incinerated or sent to landfill.

Recent regulatory changes prohibiting persistent organic pollutants from landfill or incineration plus introduction of the Plastics Packaging Tax means a chemical process for recycling PVC is urgently needed by both waste handlers and plastic producers.

This project will lead the development of the UK's first chemical recycling plant for PVC-processing in response to growing volumes of PVC waste. Halocycle will develop an innovative microwave-pyrolysis process for depolymerisation of PVC into its constituent monomers. Non-metallic process components that are inherently acid-resistant overcome the engineering challenges with handling acidic by-products. The process will be demonstrated using cable granule PVC-waste feedstocks recovered from electrical cable metal extraction processing, currently not recyclable, as a potential downstream processing step for integration into current recycling plant processes.

Technoeconomic analysis will validate technical performance and economics of process scale-up, supporting investment decision for a demonstration plant build towards commercialisation of the process. Processing of PVC into its constituent monomers provides a sustainable supply of valuable chemical building blocks for plastic production avoiding reliance on fossil-fuel based alternatives supporting a Circular Economy approach.