Destructive distillation

Destructive distillation

Destructive distillation is the chemical process involving the decomposition of feedstock by heating 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. The process breaks up or 'cracks' large molecules, generally into a mixture of hundreds of different compounds. The molecules distilled off generally are smaller and more volatile than the feedstock molecules, but some reactions polymerise small molecules into larger molecules, including heat-stable tarry substances and chars. Some feedstocks react to produce only a few products, though that is not common with organic materials, which generally produce very many.

Historically the process of destructive distillation led to the discovery of many chemical compounds before contemporary organic chemists had developed the processes to synthesise those molecules. Also, investigation of the products of destructive distillation enabled chemists to deduce the chemical nature of many natural materials.

Contents

Process

The process of pyrolysis can be conducted in a distillation apparatus (retort) to form the volatile products, which are then collected. The mass of resulting product will represent only a part of the mass of the feedstock, because much of the material remains as char and non-volatile tars. This is in contrast to simple burning in the presence of oxygen, where the (generally useless) molecules of combustion products include the oxygen; typically the combustion products of say, a hydrocarbon fuel amount to roughly four times the mass of the fuel consumed.

Destructive distillation and related processes are in effect the modern industrial versions of traditional charcoal burning crafts. As such they are of industrial significance in many countries, being particularly prominent in Scandinavia. The modern processes are sophisticated and require careful engineering to produce the most valuable possible products from the available feedstocks, as profitably as may be.[1][2]

Products

Destructive distillation is an important chemical process producing thousands of distinct chemical compounds.

Wood can be used to produce guaiacol, tar, terpenes, turpentine and Methanol together with a solid residue of charcoal.[3] [4] Coal is used to produce Coal gas and coal tar and Coke. The destructive distillation of bituminous coal produces 'coal tar pitch' a Volatile organic compound (CTPV) which contain a wide variety of polycyclic aromatic hydrocarbons (PAH's); or polynuclear aromatic hydrocarbons, or (PNA's) including naphthalene and anthracene which sublime readily, which is convenient when it is necessary to refine them and also pyrene. Many PNA's, in particular Benzopyrenes, in particular Benzo(a)pyrene are carcinogenic should only be handled and used care.

Isoprene was first isolated by destructive distillation of natural rubber[5] which is the biochemical starting point for the biosynthesis of terpenes and for many industrial syntheses as well.

It also is an increasingly promising method for recycling monomers derived from waste polymers.

References

  1. ^ Bates, John S.; Distillation of hardwoods in Canada; Pub: Ottawa, F. A. Acland, 1922. May be downloaded from: [1]
  2. ^ Klar, Max; Rule, Alexander; The technology of wood distillation, with special reference to the methods of obtaining the intermediate and finished products from the primary distillate; Pub: London Chapman & Hall 1925. May be downloaded from: [2]
  3. ^ Loos, Hermann A.; A Study on Colophony Resin; Columbia University 1900. May be downloaded from: [3]
  4. ^ DUMESNY, P. & NOYER J.; Wood products, distillates and extracts; Pub: Scott, Greenwood & Son, 1908. May be downloaded from: [4]
  5. ^ C. Greville Williams “On Isoprene and Caoutchine” Proceedings of the Royal Society of London, Vol. 10, (1859 - 1860), pp. 516-519. URL: http://www.jstor.org/stable/111688.

See also

v · d · eDistillation
Principles Simple distillation apparatus
Industrial processes
Laboratory methods
Techniques
Azeotropic · Destructive · Dry · Extractive · Fractional · Reactive · Salt-effect · Steam-based · Vacuum-based

Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Destructive distillation — Distillation Dis til*la tion (d[i^]s t[i^]l*l[=a] sh[u^]n), n. [F. distillation, L. destillatio.] 1. The act of falling in drops, or the act of pouring out in drops. [1913 Webster] 2. That which falls in drops. [R.] Johnson [1913 Webster] 3.… …   The Collaborative International Dictionary of English

  • Destructive distillation — Destructive De*struc tive, a. [L. destructivus: cf. F. destructif.] Causing destruction; tending to bring about ruin, death, or devastation; ruinous; fatal; productive of serious evil; mischievous; pernicious; often with of or to; as,… …   The Collaborative International Dictionary of English

  • destructive distillation — n. the decomposition of a material, as coal, wood, etc., by heat in the absence of air, followed by the recovery of volatile products of the decomposition by condensation or other means: a type of calcination: see PYROLYSIS …   English World dictionary

  • destructive distillation — destrukcinis distiliavimas statusas T sritis chemija apibrėžtis Be oro kaitinamų junginių skilimas. atitikmenys: angl. destructive distillation rus. деструктивная перегонка …   Chemijos terminų aiškinamasis žodynas

  • destructive distillation — dry distillation decomposition of a solid by heating in the absence of air, which results in volatile liquid products …   Medical dictionary

  • destructive distillation — Process of distillation in which a hydrocarbon or other organic compound or mixture is heated to a temperature high enough to cause its decomposition …   Petroleum refining glossary

  • destructive distillation — dry distillation, decomposition or destruction of organic substances by means of heat and an absence of air (produces products such as coke, charcoal, oils and gases) …   English contemporary dictionary

  • destructive distillation — noun Date: circa 1831 decomposition of a substance (as wood, coal, or oil) by heat in a closed container and collection of the volatile products produced …   New Collegiate Dictionary

  • destructive distillation — Chem. the decomposition of a substance, as wood or coal, by heating with a minimal exposure to air, and the collection of the volatile products formed. [1825 35] * * * …   Universalium

  • destructive distillation — noun The heating of a material, such as coal or wood, in an inert atmosphere, at a high temperature such as to cause decomposition; the principal products include oils …   Wiktionary

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”