Carbonization or Carbonisation is the term for the conversion of an organic substance into carbon or a carbon-containing residue through pyrolysis or destructive distillation. It is often used in organic chemistry with reference to the generation of coal gas and coal tar from raw coal. Fossil fuels in general are the products of the carbonization of vegetable matter.
Carbonization is often exothermic, which means that it could in principle be made self-sustaining and be used as a source of energy which does not produce carbon dioxide. (See .) In the case of glucose, the reaction releases about 237 calories per gram.
When biomaterial is exposed to sudden searing heat (as in the case of an atomic bomb explosion or pyroclastic flow from a volcano, for instance), it can be carbonized extremely quickly, turning it into solid carbon. In the destruction of Herculaneum by a volcano, many organic objects such as furniture were carbonized by the intense heat.
In one study carbonization was used to create a new catalyst for the generation of biodiesel from ethanol and fatty acids. The catalyst was created by carbonization of simple sugars such as glucose and sucrose. The sugars were processed for 15 hours at 400 °C under a nitrogen flow to a black carbon residue consisting of a complex mixture of polycyclic aromatic carbon sheets. This material was then treated with sulfuric acid which functionalized the sheets with sulfonite, carboxyl and hydroxyl catalytic sites.