The typical operating temperature window for tire pyrolysis for recovered carbon black (rCB) production is 450 °C to 600 °C.
Breakdown of the temperature zones
- 450–500 °C (Low-temperature pyrolysis)
Rubber decomposition proceeds slowly.- More heavy tar remains adsorbed on crude char.
- Less sintering of carbon black aggregates, preserving better original aggregate structure and DBP.
- Drawback: high residual tar and high volatile matter on char; requires stronger downstream thermal devolatilization.
- 500–550 °C (Optimal target range for rCB-grade char)
This is the most commonly selected setpoint for commercial rCB-focused pyrolysis plants.- Complete breakdown of vulcanized rubber polymer.
- Balanced tradeoff: full rubber conversion, while limiting excessive sintering of CB aggregates.
- Produces crude char with moderate tar content, easier for subsequent purification into premium rCB.
- 550–600 °C (High end of the range)
Faster rubber cracking, more tar converted into gas and lighter oil.- Risk: elevated temperature causes sintering between carbon black primary particles; aggregate branching collapses, DBP oil absorption drops permanently.
- Also forms more refractory sulfur and PAH species that are harder to remove later.
Temperatures above 600 °C are generally avoided for rCB-oriented pyrolysis. Although higher temperature yields more pyrolysis oil and syngas, it severely degrades the carbon black aggregate morphology, making the char unsuitable for high-performance rCB applications.
Additional important thermal notes
- This is the reactor bed temperature (solid char temperature), not just the furnace wall temperature. Wall temperature can be higher.
- Heating rate also matters: slow heating helps avoid trapping large amounts of tar inside the char matrix.
- The reactor works under oxygen-free / inert atmosphere; any oxygen ingress will cause local combustion, burn carbon and raise ash.
Quick summary table
| Temperature Range | Outcome for Crude Char | Suitability for rCB |
|---|---|---|
| 450–500 °C | High residual tar, minimal aggregate sintering | Acceptable, requires heavy devolatilization |
| 500–550 °C | Full rubber decomposition, limited sintering | Preferred for commercial rCB production |
| 550–600 °C | Low tar, higher aggregate sintering | Usable, but DBP and reinforcement properties decline |
| >600 °C | Severe sintering, collapsed aggregate structure | Not recommended for high-quality rCB |
