Destructive distillation

Destructive distillation is the chemical process of the decomposition of feedstock by heating it to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents, such as steam or phenols. It is an application of pyrolysis. The process breaks up or 'cracks' large molecules. Coke, coal gas, gas carbon, coal tar, Buckminsterfullerene, ammonia liquor, and "coal oil" are examples of commercial products historically produced by the destructive distillation of coal.

Destructive distillation of any particular inorganic feedstock produces only a small range of products as a rule, but destructive distillation of organic materials commonly produces very many compounds, often hundreds, though not all chemical products of any particular process are of commercial importance. The distilled molecules are generally smaller and more volatile than the feedstock molecules, but some reactions polymerise or condense small molecules into larger molecules, including heat-stable tarry substances and chars. Cracking feedstocks into liquid and volatile compounds, and polymerising, or the forming of chars and solids, may both occur in the same process, and any class of the products might be of commercial interest.

Currently the major industrial application of destructive distillation is to coal.

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