%0 Journal Article
%T Production d'isobut¨¨ne de haute puret¨¦ par d¨¦composition du MTBE High-Purity Isobutene Production from Mtbe
%A Meunier P. B.
%A Chaumette P.
%J Oil & Gas Science and Technology
%D 2006
%I Institut Fran?ais du P¨¦trole
%R 10.2516/ogst:1991017
%X La d¨¦composition du MTBE en isobut¨¨ne et m¨¦thanol s'accompagne de r¨¦actions secondaires (oligom¨¦risation de l'isobut¨¨ne, hydratation de l'isobut¨¨ne, d¨¦shydratation du m¨¦thanol). Les diff¨¦rents types de catalyseurs utilis¨¦s, les m¨¦canismes et les cin¨¦tiques sugg¨¦r¨¦s, ainsi que les sites actifs et les esp¨¨ces adsorb¨¦es propos¨¦s dans la litt¨¦rature sont examin¨¦s dans le cas de la r¨¦action principale, et des r¨¦actions secondaires. La formulation du catalyseur et la nature des sites actifs (Br nsted, Lewis) ont une incidence particuli¨¨re sur la r¨¦action. Les donn¨¦es de la litt¨¦rature portent essentiellement sur des catalyseurs de type r¨¦sines pr¨¦sentant une acidit¨¦ de Br nsted. Sur catalyseurs de type oxydes il appara t que les sites acides de Lewis, catalysent la r¨¦action principale, tandis que les r¨¦actions secondaires sont essentiellement dues ¨¤ la pr¨¦sence d'acidit¨¦ de Br nsted. Un contr le de l'acidit¨¦ des formulations catalytiques est n¨¦cessaire afin de minimiser les r¨¦actions secondaires, et de produire de l'isobut¨¨ne tr¨¨s pur. Under suitable conditions, methyl-tert-butyl ether (MTBE) is decomposed into isobutene (C4H8) and methanol (CH3OH). This decomposition is a reversible endothermic chemical reaction ((***) = 15. 6 kcal/mol in the gas phase). When this reaction is situated downstream from MTBE synthesis from a C4 cut, this results in the separation of the different isomers in this cut by a less costly method than the one now used, which consists of concentrated sulfuric-acid extraction. The isobutene obtained by MTBE decomposition is very pure and meets the specifications required for subsequent polymerization into butyl rubber or methyl methacrylate. The MTBE decomposition reaction is accompanied by secondary reactions such as the oligomerization of isobutene (mainly the formation of dimers), the dehydration of methanol into dimethylether, and the hydration of isobutene into tert-butyl alcohol. MTBE decomposition is catalyzed by solids with an acid nature. It has mainly been examined on catalysts of the sulfonic-resin type, but solid acid catalysts have recently appeared (zeolites, silica-alumina, supported phosphoric acid, etc. ). The different types of catalysts used are examined for the principal reaction and secondary reactions. The formulation of the catalyst and the nature of the active acid sites (Br nsted or Lewis) have great influence on the reaction. Data from the literature mainly concern catalysts of the resin type with Br nsted acidity. Concerning catalysts of the oxide type, mention is made of Lewis acid sites catalyzing the princip
%U http://dx.doi.org/10.2516/ogst:1991017