Preparation and performance of polystyrene supported acidic ionic liquid catalyst

Polystyrene supported 1-(3-sulfonic group) propyl-3-vinyl imidazolium hydrosulfate acidic ionic liquid (PS-[(CH₂)₃SO₃HVIm] [HSO₄]) catalyst was prepared through dispersion polymerization in absolute alcohol as disperse medium with polyvinylpyrrolidone as dispersion agent and 2,2′-azobisisobutyronitrile as initiator. The catalyst was characterized by means of FTIR, TG-DSC and element analysis. Results showed that the acidic ionic liquid was supported on the polystyrene support and thermal stability of the catalyst with loading 0. 892 9 mmol/g was good. The catalyst was used in the synthesis of n-butyl acetate by esterification of n-butyl alcohol and acetic acid. The catalytic system possessed characteristic of phase-transfer reaction from homogeneous phase to heterogeneous phase with addition of ethanol, so the product yield was high and the catalyst could be separated easily. Under the optimized reaction conditions of reaction temperature 92°C, n (n-butyl acetate) : n (acetate acid) 1.2 : 1, m (PS-[(CH₂)₃SO₃HVIm] [HSO₄]) : m (reactants) 0. 080 and reaction time 3 h, cyclohexane 8 mL, yield of n-butyl acetate could reach 97. 8%. After the catalyst was reused four times, yield of n-butyl acetate still achieved 80. 2%.