chemical recycling (advanced recycling)

Chemical recycling is an umbrella term for a group of technologies that break waste plastic's polymer chains through chemical or thermal-chemical reactions, producing monomers, oligomers, fuels, or feedstock chemicals rather than recycled pellets. The four main pathways are: (1) Depolymerisation — thermal or catalytic reversal of polymerisation to produce monomers (e.g. PET → BHET/TPA + MEG; PS → styrene monomer); (2) Pyrolysis — thermal decomposition in an inert atmosphere (400–600°C) producing pyrolysis oil, gas, and char; (3) Gasification — partial oxidation at 700–1,200°C producing syngas (CO + H₂); (4) Solvent dissolution/purification — dissolving specific polymers in selective solvents to separate them from contaminants and other plastics, recovering virgin-equivalent polymer solution (applicable for PS, PP, LDPE).

Chemical recycling's commercial relevance in India is growing under two converging pressures: (1) the EPR framework creates demand for processing of non-mechanically-recyclable plastics (MLP, contaminated films, Category III); (2) virgin plastic prices linked to crude oil create the economic case for chemical recyclate as a substitute. The most active segment in India as of 2024 is pyrolysis (plastic-to-fuel), driven by tyre pyrolysis infrastructure and rising fuel oil demand. Dedicated plastic depolymerisation plants (producing BHET from PET or TPA as output) are at pilot/early-commercial stage with IOCL, ONGC, and private players like Resynergi and Renewlogy operating or commissioning plants. Full-scale commercial PET depolymerisation capacity in India is less than 50,000 TPA as of mid-2024.

Quality and environmental considerations: chemical recycling produces outputs at varying quality levels. Depolymerisation produces monomers of near-virgin quality — PET from glycolysis can be polymerised to food-grade rPET indistinguishable from virgin. Pyrolysis oil from mixed plastic is broadly equivalent to a heavy naphtha or diesel blendstock but contains sulphur, chlorine (from PVC), and oxygenates that require hydroprocessing before use in fuel applications. Gasification syngas requires gas cleaning (tar removal, desulphurisation) before use in power generation or chemical synthesis. Environmental certification and lifecycle analysis are actively debated: whether chemical recycling should count as 'recycling' under EPR and EU taxonomy definitions is a policy question that affects the sector's regulatory status and credit eligibility.

For Indian recycling entrepreneurs evaluating chemical recycling: the entry cost is significantly higher than mechanical recycling. A 5,000 TPA plastic pyrolysis plant costs Rs 3–8 crore; a 5,000 TPA PET depolymerisation pilot costs Rs 10–25 crore. The economics hinge on feedstock cost (can chemical recyclers access cheap, mixed-plastic waste that mechanical recyclers won't buy?), output price (is pyrolysis oil or BHET priced above the processing cost?), and EPR credit eligibility (does CPCB recognise the specific process as qualifying for EPR credit generation?). Engage with the CPCB Technical Expert Committee output on chemical recycling classification before committing capital — the regulatory treatment is still evolving.