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Destructive distillation
From Wikipedia, the free encyclopedia
Destructive distillation is distillation involving pyrolysis. An example is the process called 'coking' when referring to the transformation of bituminous coal into coke (at 1,000 C).
The earliest historical example of destructive distillation is tar making. Pinewood slices rich in terpenes are heated in an airless container until they decompose and produce tar. The by-products are turpentine and charcoal. This process is still used in Scandinavia for tar-making.
Examples of substances that are commonly destructive distilled to extract chemicals and other materials include:
- Wood
- Soft coal
Examples of substances extracted include:
- Acetic acid
- Methyl or wood alcohol (methanol)
- Coal gas
- Tar
- Turpentine
Coal tar pitch volatiles (CTPV) are the result of destructive distillation of bituminous coal. They contain polynuclear aromatic hydrocarbons (PNA's). PNAs sublime readily and cause carcinogenic compounds in working areas. Evidence suggests that workers exposed to products of combustion or distillation of bituminous coal are at increased risk of cancer.
Principles: Raoult's law, Dalton's law, Reflux, Fenske equation
Industrial processes: Batch distillation, Continuous distillation
Laboratory methods: Rotary evaporator, Kugelrohr, Spinning band distillation
Techniques: Fractional distillation, Vacuum distillation, Extractive distillation, Reactive distillation, Dry distillation, Destructive distillation, Azeotropic distillation, Steam distillation