A benign preparation of sec-butanol via transesterification from sec-butyl acetate using the acidic Imidazolium ionic liquids as catalysts

• Green synthesis of sec-butanol with an environmentally friendly catalyst was proposed.
• Screening of transesterification catalyst was performed.
• In the batch reactor, synthesis of sec-butanol was optimized using [HSO3-PMIM]HSO4 as catalyst.
• In the batch reactive distillation column, the conversion of sec-butyl acetate reached 97.72% under the optimized conditions.
• The acidic ionic liquids ([HSO3-PMIM]HSO4) showed high catalytic activity and reuse performance on the transesterification.

Five acidic Imidazolium ionic liquids (ILs) were synthesized and the catalytic activity for the preparation of sec-butanol via the transesterification of sec-butyl acetate (SBAC) with methanol were investigated. Among them, 1-(3-sulfopropyl)-3-methylimidazolium hydrogen sulfate ([HSO3-PMIM]HSO4) performed best. In the batch reactor, the influences of various reaction conditions on the transesterification were investigated using [HSO3-PMIM]HSO4 as catalyst. Under the optimal reaction conditions, the conversion of SBAC was 89.30%. In addition, in order to enhance the conversion of SBAC, reactive distillation was carried out in the presence of [HSO3-PMIM]HSO4 as catalyst. A high conversion of the SBAC of 97.72% was obtained under the optimal reaction conditions. In order to evaluate the catalyst stability, the ILs was repeatedly used for 5 times without obvious loss of activity after simple separation from the mixture. The results indicated that [HSO3-PMIM]HSO4 showed better catalytic activity and reuse performance. Therefore, an environmental friendly technology for the preparation of sec-butanol catalyzed by ILs is provided.