Pyrolysis is a thermal treatment method applicable to any organic (carbon-based) substance, whether pure or in a mixture. It involves subjecting the material to high temperatures in the absence of oxygen, leading to a chemical and physical breakdown into various molecules. This decomposition occurs due to the limited thermal stability of the material’s chemical bonds, allowing them to be broken down by heat.

The process of thermal decomposition results in the creation of novel molecules, often possessing superior properties compared to the original residue. This characteristic has made pyrolysis an increasingly important industrial process, as it adds significant value to common materials and waste.

While pyrolysis is often linked with thermal treatments, it differs from combustion and gasification processes, which involve the partial or complete oxidation of the material. Pyrolysis relies on heating in the absence of air, making it primarily an endothermic process that yields products with high energy content.

Pyrolysis produces solid residue (charcoal, biochar), liquid, and non-condensable gases (H2, CH4, CnHm, CO, CO2, and N). In some applications, the liquid phase is extracted from the pyrolysis gas during its cooling, allowing both streams to be utilized together, for example, by providing hot syngas directly to a burner or oxidation chamber.