Pyrolysis Influencing Factors and Their Effects
A process control reference table showing how six pyrolysis variables (temperature, time, pressure, particle size, heating rate, feedstock) should be set to maximise each of six target outputs — oil, gas, char, limonene, BTX aromatics, and high-quality char.
| What You Want | Temperature | Time | Pressure | Particle Size | Heating Rate | Feedstock |
|---|---|---|---|---|---|---|
| Maximum oil yield | 425-500 degrees Celsius | Shorter | Lower (vacuum) | Smaller | Faster | Any |
| Maximum gas yield | Higher (600+ degrees Celsius) | Longer | Higher | Smaller | Faster | Any |
| Maximum char yield | Lower (350-450 degrees Celsius) | Shorter | Higher | Larger | Slower | Any |
| High-value chemicals (limonene) | Lower (around 450 degrees Celsius) | Shorter | Vacuum | Smaller | Moderate | Any |
| Aromatic-rich oil (BTX) | Higher (550+ degrees Celsius) | Moderate | Atmospheric | Smaller | Higher | Passenger car tyres |
| High-quality char | Higher (600+ degrees Celsius) | Longer | Lower | Any | Any | Any |
Beyond definitions
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How to read this table
- Each row is one target output; columns show the temperature, time, pressure, particle size, heating rate, and feedstock conditions that favour that output.
- 'Higher' and 'Lower' in the columns are relative to standard operating conditions — not absolute thresholds. Actual degree of adjustment depends on reactor design.
- These are tendencies, not binary switches — multiple outputs are produced simultaneously; these conditions shift the balance, not eliminate competing products.
About this table
Tyre pyrolysis is not a fixed process — operators can tune six input variables to shift the distribution of outputs between oil, gas, char, and speciality chemicals. This table is the process control reference that connects desired output targets to the operating conditions that favour them, helping plant operators and designers select the right configuration for their target product mix.
To maximise oil yield, the operator sets temperature at 425–500°C, uses shorter residence times, lower pressure (or vacuum), smaller feedstock particle size, and faster heating rate. At these conditions, the volatilised hydrocarbons are rapidly swept out of the reactor before secondary cracking into gas can occur — maximising the liquid condensate fraction. This is the most common operating strategy for Indian pyrolysis plants where Tyre-derived Pyrolysis Oil (TPO) is the primary revenue product.
For maximum gas yield, conditions shift to higher temperature (600°C+), longer residence time, and higher pressure — these conditions promote secondary cracking of oil vapours into non-condensable gases (methane, ethylene, propylene), which are typically used as fuel for the reactor burner rather than sold externally. Maximum char yield (lower temperature 350–450°C, shorter time, high pressure, large particle size, slow heating) applies when the operator targets carbon black or solid fuel production rather than liquid oil. The slower heating rate and larger particle size mean incomplete conversion of the rubber to gas, leaving a higher char residue.
High-value chemicals (limonene) — a specialty chemical produced primarily from natural rubber pyrolysis at lower temperatures around 450°C — requires vacuum conditions and shorter residence time to prevent limonene decomposing at higher temperatures. Aromatic-rich oil (BTX — benzene, toluene, xylene) is favoured by higher temperature (550°C+), moderate time, atmospheric pressure, and specifically passenger car tyre feedstock which has higher synthetic rubber content conducive to BTX formation. High-quality char (suitable for carbon black production) requires the highest temperatures (600°C+) and longest residence times to remove all residual volatile matter and produce a char with lower ash and higher graphitic structure.
Key insights
- Maximum oil yield (425–500°C, shorter time, lower pressure) is the default strategy for Indian pyrolysis operators because TPO is the primary revenue driver — these conditions work for both ABAP Batch and continuous reactor types.
- High-quality char production (600°C+, longer time) requires significantly more energy input per tonne — the energy cost increase must be weighed against the price premium for higher-grade carbon black versus standard char.
- Limonene production requires vacuum conditions and lower temperatures around 450°C — only feasible in plants with vacuum-capable reactors and specific condensation infrastructure designed to capture this lighter, lower-boiling fraction.
- Passenger car tyres specifically favour BTX aromatic oil production — operators with consistent access to passenger car tyre feedstock can consider BTX-optimised operation if buyers for aromatic-rich oil are available.
Methodology & sources
Process condition trends described are based on published tyre pyrolysis research and commercial plant operating data as of 2024. Actual reactor response to these levers depends on reactor design, heating system, condensation configuration, and feedstock composition. Specific operating conditions should be validated during plant commissioning through trial runs with the target feedstock. Limonene production is technically proven but commercially limited in India — verify buyer availability before designing specifically for limonene recovery.
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