Alkylating isobutane with C_3-C_5 olefins has attracted more attention in gasoline manufacture. Its importance stems from several key advantages offered by the alkylate, including high octane number, low density, low vapor pressure and low levels of undesired emissions. Current alkylation processes running in plants rely only on H_2SO_4 and HF as catalysts. However, both of these catalysts suffer from disadvantages such as high acid consumption, strict safety requirement and relatively severe corrosion to facilities. Therefore, efforts have been made to find more environmentally benign system, for example, alkylation over zeolites, hyteropolyacids and various solid acids possessing super acidity. Room temperature ionic liquids (ILs) as clean catalysts and solvents have received significant attention in the past decade. Among them the AlCl_3 based ILs with their variable acidities have been shown to be promising alternative to traditional acidic catalysts. In our research, [bmim]Cl / AlCl_3 ([bmim] = 1 - butyl - 3 - methyl -imidazolium) were used as both solvent and catalyst in the alkylation of isobutane with 2-butene. Their comparable performance to H_2SO_4 and great potential for recycling were demonstrated.
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