Tyre Pyrolysis Explained: Turning Tyres into Oil, Carbon, and Gas

Updated on: 3rd March 2026 By:

What Tyre Pyrolysis Is and Why It Matters

Tyre pyrolysis is the thermal decomposition of rubber in the complete or near-complete absence of oxygen. Heating rubber to temperatures of 400 to 700°C in an oxygen-free environment breaks down the complex polymer chains of the rubber compound into simpler organic molecules, which leave the reactor as gases and vapours that are subsequently condensed into liquid oil. The solid residue remaining in the reactor is a char containing carbon black and inorganic material from the tyre compound.

Pyrolysis matters to the tyre recycling industry because it offers a route to chemical recycling, converting tyre material into useful chemical products, rather than simply physical recycling as crumb rubber or thermal treatment as TDF. If the outputs of tyre pyrolysis, particularly the oil and the recovered carbon black, can substitute for virgin petrochemical products in downstream industries, the pyrolysis route closes a material loop that physical recycling cannot: it converts tyre rubber back toward the chemical feedstocks from which synthetic rubber was originally made.

This is a technically demanding objective that the pyrolysis industry has been working toward for decades. The technology has matured significantly in recent years, several commercial-scale facilities now operate in Europe and the UK, and investment in the sector has grown as sustainability pressures on tyre manufacturers and on the rubber industry have intensified. Understanding where the technology is now, what it produces, and how its economics compare to competing routes is essential context for the tyre processing industry.

Gradeall International manufactures the front-end tyre processing equipment that feeds pyrolysis facilities, including sidewall cutters, rim separators, and shredding preparation equipment from the full tyre recycling range. The quality of the feed material entering a pyrolysis reactor affects output quality; Gradeall’s equipment produces well-prepared, contamination-reduced feed that improves pyrolysis process efficiency. With nearly 40 years of manufacturing experience and equipment in over 100 countries, Gradeall supports the tyre processing chain across all processing routes.

The Pyrolysis Process: Temperature, Atmosphere, and Reactor Design

Tyre pyrolysis occurs when organic material is heated in the absence of oxygen. The absence of oxygen is critical: if oxygen were present, the material would combust rather than thermally decompose. Maintaining an oxygen-free atmosphere in the reactor requires either purging with an inert gas (typically nitrogen), sealing the reactor completely, or creating a sufficiently reducing atmosphere through the partial combustion of the non-condensable gas produced by the pyrolysis process itself.

Temperature ranges and their effects. Different temperature ranges produce different product distributions. At lower pyrolysis temperatures (300 to 450°C), the balance of products shifts toward the liquid oil fraction. At higher temperatures (500 to 700°C), more of the organic content is converted to non-condensable gas, and the carbon residue (char) has different properties. Commercial pyrolysis processes are typically operated in the 450 to 550°C range as a compromise that maximises liquid oil yield while maintaining manageable char properties.

Reactor designs. Several reactor configurations have been developed for commercial tyre pyrolysis:

Batch reactors load a quantity of tyre material, heat it through the pyrolysis cycle, and then unload the char before the next batch. Simple in design but lower in throughput efficiency than continuous systems. Suitable for smaller-scale operations.

Rotary kilns provide continuous processing by rotating the reactor vessel, tumbling the tyre feed material through a temperature gradient as it travels from inlet to outlet. The rotation provides good heat transfer to the material and allows continuous operation. Rotary kiln pyrolysis is one of the most widely used commercial configurations.

Fixed-bed and moving-bed reactors process material in a stationary or slowly moving bed through which heat is transferred. These configurations require careful feed size management to ensure adequate heat transfer through the bed.

Microwave pyrolysis uses microwave energy rather than conventional heating to achieve thermal decomposition, potentially offering more selective and energy-efficient heating. Microwave pyrolysis is at an earlier commercial development stage than conventional thermal systems.

The Three Main Outputs of Tyre Pyrolysis

Pyrolysis oil (tyre-derived oil, TDO). The liquid fraction condensed from the pyrolysis vapours is a complex mixture of aromatic and aliphatic hydrocarbons. Its properties vary with the tyre feed composition and the pyrolysis temperature: typically it has a calorific value of 40 to 44 MJ/kg (higher than fuel oil at approximately 42 MJ/kg), a relatively high sulphur content from the vulcanisation chemistry of the original rubber, and a complex composition that differs significantly from conventional petroleum-derived fuels.

TDO can be used directly as a fuel in industrial burners and some marine applications. It can also be fed to refinery processing units as a chemical feedstock for upgrading to higher-quality fuels or petrochemicals. Several UK and European pyrolysis operators have developed routes for selling TDO as an industrial fuel or as a refinery feedstock. The sulphur content of TDO is a challenge for some fuel applications where sulphur limits apply.

Recovered carbon black (rCB). The solid char from tyre pyrolysis contains carbon black, the fine carbon particles that were originally used as a reinforcing filler in the tyre compound. The potential to recover and re-use this carbon black as a substitute for virgin carbon black in new rubber products, reducing the demand for carbon black from fossil fuel combustion, is one of the most commercially compelling aspects of tyre pyrolysis.

The challenge has been quality. Virgin carbon black is a carefully controlled industrial product with specific particle size, surface area, and structure properties. Carbon black in the pyrolysis char is intermixed with inorganic residues from the tyre compound (zinc oxide, calcium carbonate, silica from silica-filled tyre compounds) and has surface chemistry that differs from virgin carbon black due to the pyrolysis thermal treatment. Producing rCB that meets the quality specifications needed for premium rubber applications requires post-processing of the raw char, including cleaning, milling, and characterisation.

Progress on rCB quality has been significant. Several producers now offer certified rCB grades that have been demonstrated to replace a meaningful proportion of virgin carbon black in rubber and plastic compounds. Some tyre manufacturers have announced programmes to incorporate certified rCB into new tyre production, creating a closed-loop story from used tyre to new tyre that the sustainability narrative of the automotive industry is actively seeking.

Non-condensable gas. The gas fraction from tyre pyrolysis has a calorific value of approximately 40 MJ/m³ and is typically used within the pyrolysis facility as fuel to heat the reactor. Using the process gas internally improves the overall energy efficiency of the pyrolysis operation; a facility that is largely energy self-sufficient from the process gas has significantly better economics than one requiring external energy input throughout the process.

Steel Recovery from Pyrolysis

The steel wire and belt reinforcement in the tyre is recovered from the pyrolysis char as clean metallic steel. Because the organic material has been thermally removed, the steel recovered from pyrolysis char is clean and uncontaminated by rubber residue. This clean steel can be sold as scrap metal. For tyres with high steel content (truck and OTR tyres), the steel recovery from pyrolysis is a significant by-product revenue stream.

Commercial Viability: Where Tyre Pyrolysis Is Today

Commercial scale tyre pyrolysis has moved from demonstration phase to genuine commercial operation over the past decade, with several UK and European facilities now operating continuously and producing marketable outputs. The economics have improved as:

TDO markets have developed with industrial buyers and refinery-compatible products. rCB quality has improved and the market for certified rCB has grown. Carbon pricing and sustainability pressure on downstream industries have increased the premium available for low-carbon circular economy products. Technology costs have reduced as designs have been refined through operational experience.

The pyrolysis route remains more capital-intensive than mechanical processing (crumb rubber production) or baling for comparable throughput. Operating costs include energy input, feed preparation, output management, and environmental compliance. The economics are most favourable when all three outputs, oil, rCB, and steel, can be sold at prices that together cover costs and margins; a facility that can only market the oil but not the rCB faces significantly tighter economics.

“Pyrolysis is the route that gets closest to genuine chemical recycling of rubber, and the commercial case is strengthening year by year as the quality of rCB improves and the market for low-carbon feedstocks develops,” says Conor Murphy, Director of Gradeall International. “Our role is in the feed preparation stage. Well-prepared, clean, appropriately sized tyre feed produces better pyrolysis output; the front-end processing investment pays dividends in output quality.”

Contact Gradeall International for tyre feed preparation equipment including sidewall cutters, rim separators, and handling systems for pyrolysis facility applications.

Frequently Asked Questions

What tyre preparation is required before pyrolysis processing?

Most pyrolysis reactors require tyres to be shredded to a specific chip size before reactor feed. Whole tyres are too large for most reactor designs and present heat transfer problems. Rims must be removed before shredding to prevent steel rim contamination of the char and to protect shredding equipment. Gradeall’s tyre rim separator and sidewall cutting equipment prepares tyres for the size reduction needed before pyrolysis reactor feed.

Is tyre pyrolysis a permitted activity in the UK?

Tyre pyrolysis facilities in the UK require an environmental permit from the Environment Agency (England), SEPA (Scotland), NRW (Wales), or NIEA (Northern Ireland). The permit conditions cover the thermal process, emissions to air, waste acceptance criteria, and management of outputs. Permitting a new pyrolysis facility is a significant regulatory process requiring detailed technical and environmental assessment.

How does the carbon footprint of tyre pyrolysis compare to landfill or incineration?

Tyre pyrolysis compares favourably to landfill (the landfill ban applies to tyres) and to simple incineration from a waste hierarchy perspective, as it recovers material products rather than only energy. The lifecycle carbon footprint of pyrolysis is complex to calculate and depends on what the outputs substitute for. rCB substituting for virgin carbon black and TDO substituting for fossil fuel produce carbon savings relative to the counterfactual; the net position is positive but the precise figure is production and market-specific.