Ionic liquid enhanced alkylation of iso-butane and 1-butene

The alkylation of iso-butane with 1-butene was catalyzed by triflic acid (TFOH) coupled with a series of protic ammonium-based ionic liquids (AMILs), and the addition of the AMILs dramatically enhanced the efficiency of TFOH for the alkylation reaction. Up to 85.1% trimethylpentanes (TMP) selectivity and 98 research octane number (RON) were achieved with the optimized TFOH/AMIL catalyst (75 vol.% triflic acid and 25 vol.% triethylammonium hydrogen sulfate), which were much better than that with the commercial H2SO4 catalyst (65% TMP selectivity, 97 RON) and pure triflic acid. The addition of AMILs increased the I/O ratio dissolved in the catalyst system and adjusted the acidity of the TFOH/AMILs catalyst system, which were highly beneficial to the alkylation reaction and resulted in high TMP selectivity and high RON.

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► Ten ammonium based protic ionic liquids (AMILs) coupled with triflic acid were used as catalysts for the iso-butane/1-butene alkylation.
► Up to 85.1% trimethylpentanes (TMP) and 98 research octane number (RON) was achieved with the optimized system.
► The catalyst could be reused at least 5 cycles without significant loss of activity.