alkylation
- Domaine
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- pétrole et gaz naturelconversion des hydrocarbures
- Date
Définitions :
Réaction entre un alcène et un hydrocarbure à chaîne ramifiée.
((Elle)) consiste à former une nouvelle substance en remplaçant dans un composé un atome d'hydrogène par un groupe alkyle.
Notes :
Deux hydrocarbures différents, tels qu'une paraffine et une oléfine peuvent être mis en réaction en présence d'un catalyseur pour produire de l'iso-octane à partir d'isobutylène et d'isobutane.
L'alkylation sert à réduire la pollution produite dans les gaz d'échappement des moteurs par la combustion des oléfines.
En raffinerie, on utilise cette réaction entre l'isobutane et un alcène (éthylène, propène, butène ou penthène) pour former des composés antidétonants qui donneront des essences à indice d'octane élevé.
Terme :
- alkylation n. f.
Terme associé :
- alcoylation n. f.
Traductions
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anglais
Date :Définition
In petroleum processing, a process by which a branched chain hydrocarbon, usually isobutane, is reacted with an alkene (ethylene, propene, butene, pentene are all used) to form compounds for blending to give gasoline with a high octane number. Also the process by which benzene and other aromatics are converted to aromatic blending agents by the addition of an alkene to the benzene ring.
Addition of an alkyl group to an organic compounds of higher molecular weight compounds rather than the breaking down or cracking of large molecules. The catalysts most widely used are aluminum chloride, hydrogen fluoride, and sulphuric acid, at low temperatures and pressures. Thermal processing is carried out at temperatures of about 480 °C (900 °F) and pressures of several thousand pounds per square inch.
Gasoline manufacturing process in which larger hydrocarbons are made from small ones. The process employs either sulphuric acid or hydrogen fluoride as catalyst. The isoparaffinic products of alkylation have octane numbers, and its major value is in the exceptional antiknock quality of its product.Notes :
Alkylation may be carried out by thermal means the use of a catalyst results in less severe conditions and hence process plant. Sulphuric acid or hydrofluoric acid as used as catalysts.
The petroleum industry utilizes alkylation to make isooctane neoexane, etc., by reacting olefins such as ethylene or propylene with a branched-chain paraffinic hydrocarbon. Ethylbenzene and cumene are also prepared by alkylating benzene with ethylene or propylene.Terme :
- alkylation