Decarbonisation Technology - November 2023 Issue

75.5% landll

8.7% recycle

15.7% energy

360 million tonnes of plastic produced in 2018

Plastic use

End of life

Figure 2 Life cycle of plastics (according to US EPA data for 2018)

fosters a sense of shared responsibility for environmental stewardship and creates a platform for dialogue and partnership among stakeholders. This collaboration can lead to more effective policies, streamlined waste management systems, and increased public awareness. Plastic recycling and upcycling Plastic waste has emerged as a significant environmental challenge, necessitating innovative solutions to minimise its impact. The manufacturing of plastic has risen with a yearly expansion of 8.4% since 1950. By 2018, the yearly plastic production had reached 360 million tons, and it is projected to escalate to 500 million tons by 2025 (TCGR report). Research into various choices for handling plastic waste indicated that the majority of discarded plastic waste is managed by depositing it in landfills. As per data provided by the US Environmental Protection Agency

(EPA), in 2018, 75.5% of all generated plastic waste was disposed of in landfills, 15.7% was used for energy retrieval, and only 8.7% of plastic underwent recycling (US; EPA, 2021) (see Figure 2 ). This underscores the notably high proportion of plastics that are directed to landfills. However, the circular economy offers a glimmer of hope through advanced recycling techniques. Innovations like chemical recycling break down plastic polymers into their constituent monomers, allowing them to be reprocessed into new plastics with virgin- like quality. Additionally, upcycling methods can transform plastic waste into higher-value products, such as textiles or construction materials, giving discarded plastics a new lease of life. Advanced recycling technologies, such as chemical and mechanical recycling, offer promising avenues to tackle plastic waste and enable the recovery of valuable materials for integration into new product life cycles. These technologies play a vital role in promoting a circular economy in the petrochemical industry. Chemical recycling is a process that involves breaking down plastic waste into its molecular components through various methods, such as pyrolysis, gasification, hydrogenolysis, depolymerisation, and liquefaction (see Figure 3 ). Pyrolysis, gasification, hydrogenolysis, and hydrothermal treatment are thermochemical methods to convert plastic wastes into naphtha-like feedstocks for the production of petrochemicals. The use of catalysts in these methods might give some control over the product distribution and process conditions. Depolymerisation involves the conversion of complex polymers back into their monomeric units, which can then be used as building blocks for the production of new plastics or

Chemical recycling Physical recycling

Rened hydrocarbons

Pyrolysis Gasication Hydrogenolysis Hydrothermal treatment

Petrochemicals

Monomers

Depolymerisation

Polymers

Solvent based purication

Plastic products

Mechanical recycling

Post consumer recovery

Re-use

Figure 3 Plastic recycling methods