Isobutane/2-butene alkylation catalyzed by binary mixtures of acidic ionic liquids (ILs) and strong acids (sulfuric acid or H 2 SO 4 and triflic acid or CF 3 SO 3 H) was investigated. The catalytic performances of H 2 SO 4 and CF 3 SO 3 H were considerably improved when ILs were added. Using [Emim][OTf]-CuCl/H 2 SO 4 as the catalyst, an alkylate with a high content of the desired trimethylpentane (up to 79.6 wt%) and a high research octane number (up to 99.1) was obtained. The results of electrospray ionization-mass spectrometry indicated that the better distributions of the products obtained with the IL/acid mixtures were due to the Cu-containing anions and cations of the ILs.

A novel and efficient method was established to investigate isobutane/2-butene alkylation. In this method FT-IR spectroscopy was used to determine the presence of the composite ion (AlCuCl5-) in the composite ionic liquid (CIL). The trimethylpentane selectivity of the composite ionic liquid for isobutane/2-butene alkylation was also estimated by monitoring the shift of IR absorption bands in the range 1636–1685 cm-1. A detailed study of the alkylation of isobutane /2-butene in CIL media has been conducted using 1-alkyl-3-methylimidazolium halide/X aluminum chloride-y cuprous (I) chloride ([CnMIM]Cl/xAlCl3-yCuCl) encompassing various alkyl groups (n=4:B, butyl-, n=6:H, hexyl-, and n=8: O, octyl-)respectively. The ionic liquids showed higher selectivities of C8 as well as the TMP/DMH ratios in alkylates. The better catalytic performance of CIL can be attributed to the presence of the composite ion in it, and the catalytic performance of the chloroaluminate ionic liquid can be indicated by the 1685 cm-1band of FT-IR spectroscopy.

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