What is the difference between combustion and pyrolysis?

• Combustion, also known as burning, is a high-temperature exothermic redox chemical reaction that occurs between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, to produce oxidised, often gaseous products in a mixture known as smoke.
• Pyrolysis is the process of subjecting substances to extremely high temperatures in relatively inert environments in order to facilitate thermal decomposition. It is important to note that the pyrolysis process causes a chemical change in the substance being pyrolyzed (the chemical compositions of the initial reactant feedstock and the final product are different). The term "pyrolysis" has Greek roots and can be roughly translated as "fire separating."

Combustion:

Combustion is a process of heating the substance in presence of excess oxygen in the atmosphere in order to convert:

• the carbon to carbon dioxide (oxidation)
• hydrogen to water (oxidation)

Gas chromatography is used for measurements

Pyrolysis:

Pyrolysis (thermal decomposition) is a process of heating the substance in the absence of added oxygen in the atmosphere in order to convert:

Here the substance passes through a catalyst