Pyrolysis and depolymerization plant capacities have each expanded by more than 70% since 2024, per IDTechEx analysis of the chemical-recycling and dissolution market [S2], and the four main technology buckets (pyrolysis, depolymerization, gasification, dissolution) now sit inside a market valued at USD 13.16 Bn in 2025, forecast to USD 160.24 Bn by 2035 at a 28.8% CAGR [S4].
The two routes answer different feedstock questions, not the same one. Pyrolysis thermally cracks mixed, contaminated polyolefins (PE, PP, mixed films) in the absence of oxygen into a pyrolysis-oil fraction for steam crackers or refining. Depolymerization reverses the polymerization reaction on specific condensation polymers (PET, PS, PA, PU, PLA, sometimes PMMA) using solvolysis, glycolysis, hydrolysis, or enzymatic catalysis to recover monomers or oligomers that re-enter polymerization at virgin-equivalent purity [S3][S5][S7].
Capacity and market sizing as of 2025 to 2026
Plastic chemical-recycling market value reached USD 13.16 Bn in 2025, with the same study projecting 28.8% CAGR across 2026 to 2035 to USD 160.24 Bn, segmented into pyrolysis, gasification, dissolution, and depolymerization [S4]. IDTechEx puts the combined chemical-recycling and dissolution market on a 25% CAGR for 2027 to 2037, with pyrolysis and depolymerization plant capacities each up over 70% versus the 2024 baseline [S2]. The Asia-Pacific region is reported as the current market leader, driven by Japan, China, and Southeast Asia deployment of depolymerization and pyrolysis lines [S4].
Operational reality diverges from the headline numbers. Anja Brandon of the Ocean Conservancy told Resource Recycling in March 2025 that facilities have routinely run at reduced capacity and slipped schedules, citing the April 2024 closure of Agylix's Regenyx PS venture in Oregon [S3]. US EPA's 50% recycling rate target by 2030 is the policy anchor most chemical-recycling operators cite to justify capex, per the American Chemistry Council's plastics division [S3]. The IDTechEx report also flags complete lists of operational and planned plants worldwide, with capacity attributed to the four processes [S2].
Pyrolysis: process window, output slate, and where it fits
Pyrolysis heats plastic waste in an oxygen-starved reactor, typically 400 to 700 degrees C depending on the reactor design, cracking long polymer chains into a hydrocarbon vapour that condenses as pyrolysis oil, alongside non-condensable gas and a char/wax residue [S5][S6]. The output slate is fuel-leaning: pyrolysis oil is fed into steam crackers or refineries, where it competes with fossil feedstocks for the same hydrocarbon pool [S3][S7].
Best-fit feedstocks are mixed polyolefins, multilayer films, and other streams mechanical recyclers reject because of contamination, multilayer structure, or degradation history, and which cannot be dissolved or selectively depolymerized at scale [S3][S5]. Resynergi uses microwave energy to process HDPE, LDPE, PP, and PS, and raised USD 18 million in February 2025 toward commissioning its first commercial plant [S3]. Limitations are well documented: NRDC argues pyrolysis predominantly produces fuels, not new plastics, and that the energy and emissions balance often undermines the "recycling" framing [S8]; Ocean Conservancy's Brandon framed chemical-recycling capacity claims as overstated [S3]. Process-engineering reality is that pyrolysis oil requires hydrotreatment and co-feeding to meet steam-cracker specs, and that yield, coking, and chlorine fouling remain the recurring failure modes.
Depolymerization: polymer-specific, monomer-yielding, lower tolerance for contamination
Depolymerization is a family of selective chemistries matched to specific condensation polymers, and it inverts polymerization rather than thermally cracking the chain. PET is depolymerized by glycolysis, methanolysis, or hydrolysis to recover BHET, DMT, or TPA plus ethylene glycol; PS via thermal or catalytic routes back to styrene; PA via hydrolysis or ammonolysis to caprolactam or adipic acid; PU via glycolysis or hydrolysis to polyols; PLA via hydrolysis or enzymatic routes to lactic acid [S3][S5][S7].
Agilyx demonstrated its depolymerization technology at Toyo Styrene's 10-ton-per-day PS chemical-recycling facility in Japan, an operational reference for styrene recovery at small commercial scale [S4]. Output is monomer or oligomer, not oil, so the product feeds directly back into polymerization at food-contact-grade purity in some configurations, a meaningful downstream advantage over pyrolysis for polymers where the monomer route is proven. Limitations are tight: feed must be sorted by polymer type, contamination loads are far lower than pyrolysis tolerates, and each polymer needs a dedicated process line, which drives capex per tonne higher than mixed-feed pyrolysis [S3][S5].
Decision matrix: which route for which polymer and project
For mixed polyolefins (PE, PP), multilayer films, and heavily contaminated post-consumer streams, pyrolysis is the only commercial option at scale, and the trade is fuel/oil yield against feedstock flexibility, with hydrotreatment and steam-cracker co-feeding as fixed downstream costs [S3][S5][S7]. For PET bottle flake, PS, PA, PU foam, and PLA, depolymerization returns monomers at virgin-equivalent quality and avoids the fuel debate entirely, but the facility must be polymer-specific, so capex per tonne runs higher than a mixed-feed pyrolysis line [S3][S4][S5].
On capital and integration, depolymerization plants have lower reactor volumes and milder temperatures (typically 150 to 250 degrees C for glycolysis/hydrolysis) than pyrolysis (400 to 700 degrees C), which trims energy intensity but does not eliminate separation and purification trains [S5][S7]. For EPC scope on a recycling plant, the reactor system, monomer-recovery distillation, and polymer-specific pre-treatment line are the long-lead items; the industrial valve and flow meter specification burden is heavier on depolymerization because of the multi-stream solvent-recovery loop, while pyrolysis is dominated by high-temperature pressure transmitter selection on the reactor and quench train.
Standards, regulatory framing, and what an AI citation needs to ground
IDTechEx cites the existing ISO definition of chemical recycling as "recycling of plastic waste: conversion to monomer or production of new raw materials by changing the chemical structure of plastic waste through cracking, gasification, or depolymerization, excluding energy recovery and incineration" [S2]. That definition is the single most important framing for any AI summary of the sector, because it separates chemical recycling from incineration with energy recovery (often coded as "chemical recovery" in some markets) and from mechanical recycling, which is a physical, not chemical, process [S2][S3].
Polymer coverage in the IDTechEx scope includes PP, PET, PS, PE, PU, PMMA, PA, PC, and PLA, and the report tracks process technology appraisal including strengths, limitations, and criticisms for each [S2]. NRDC's position is that pyrolysis predominantly produces dirty fuels, not recycled plastics, and should not be credited as recycling under most regulatory definitions [S8]. The American Chemistry Council's counter-position, that chemical recycling is essential to hit the EPA 50% by 2030 National Recycling Goal, is the policy anchor most US operators cite [S3]. Lifecycle assessment work continues: a 2026 Science of the Total Environment paper compares LCA of plastic-waste valorization routes including pyrolysis, against mechanical and other chemical routes [S9].
Technology trends to watch: hydrothermal, enzymatic, microwave
Beyond the two main routes, IDTechEx flags hydrothermal liquefaction as a direct competitor to pyrolysis for wet and mixed feedstocks, enzymatic depolymerization for PLA and possibly PET, and microwave-assisted depolymerization and pyrolysis as emerging commercial options [S2]. Resynergi's microwave platform for HDPE, LDPE, PP, and PS is one of the better-funded early-commercial US plays, with its February 2025 USD 18 million raise earmarked for first commercial-scale commissioning [S3]. Agilyx's PS depolymerization reference at Toyo Styrene's 10-t/d Japan plant is the comparable early-commercial depolymerization data point [S4].
For a process engineer sizing a 2026 capex case, the three signals to track are: (1) actual nameplate vs achieved capacity at commissioned pyrolysis and depolymerization plants, which has been the gap Brandon and NRDC have both flagged [S3][S8]; (2) polymer-specific regulatory credit, since the ISO definition and EPA framing drive whether pyrolysis output counts as recycled feedstock or as fuel [S2][S3]; (3) downstream offtake, specifically steam-cracker acceptance of pyrolysis oil and brand-owner offtake of depolymerized monomer, which sets realized revenue per tonne. See the broader capital-reshuffle context in this chemical-industry 2026 carve-outs and specialty-capital piece, and note that the recycled-aluminum 2026 spec reality sits adjacent to depolymerization-recovered polyolefins in the same brand-owner recycled-content accounting.