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Energy & Fuels 2009, 23, 70–73
Oligomerization of Isobutene Catalyzed by Iron(III) Chloride Ionic Liquids Shuqing Yang, Zhichang Liu,* Xianghai Meng, and Chunming Xu State Key Laboratory of HeaVy Oil Processing, China UniVersity of Petroleum, Changping District, Beijing, 102249, China ReceiVed August 21, 2008. ReVised Manuscript ReceiVed October 13, 2008
The oligomerization of isobutene catalyzed by ionic liquids containing FeCl4- and Fe2Cl7- was conducted in an autoclave. The conversion of isobutene was above 83 wt%, and the selectivity of diisobutene plus triisobutene was above 75% when the mole ratio of FeCl3 to [(C2H5)3NH]Cl ranged from 1.2:1 to 2:1. The addition of cuprous chloride to the ionic liquid increased the conversion of isobutene and the selectivity of diisobutene plus triisobutene. The latter reached 90% at the mole ratio of CuCl to [(C2H5)3NH]Cl-1.5FeCl3 of 0.25:1. The reaction pathway of the oligomerization of isobutene catalyzed by iron(III) chloride ionic liquids was explained by the carbonium ion mechanism.
1. Introduction The oligomerization of isobutene is an important process in petrochemical and petroleum refining industries.1 Diisobutene is used as an intermediate of surface-active and plasticizing agent or a high octane number gasoline blending stock.2 Triisobutene is used to produce epoxy resin solidifying agent, dodecylbenzene, antirust, lubricant, and gas oil additives.3,4 Attempts have been made by using various solid acids such as silica-supported phosphoric acid,5,6 zeolite,7,8 and cation ion-exchanged resins9-11 as catalysts for the oligomerization of isobutene. However, the activity and the selectivity of these solid acid catalysts are too low for industrial application; moreover, solid acid catalysts deactivate quickly. Room temperature ionic liquids (RTILs) are salts in liquid phase at low temperature (
