Preparation and catalytic performance of silica gel immobilized acidic ionic liquid catalyst

A novel Br0nsted acidic ionic liquid catalyst 3-(-3-triethoxysilylepropyl)-l-methylimidazolium hydrogen sulfate ([(TESP) MIm] HSO₄) supporting on silica gel was prepared with covalent bond grafting method and characterized by means of element analysis, Fourier transformed infrared spectroscopy (FT-IR) and thermogravimetric analysis-differential scanning calorimetry (TGA-DSC). The results showed that the catalyst ([(TESP) MIm] HSO₄/silica gel), Which loaded ionic liquid [(TESP)MIm]HSO₄ 1.503 mmol/g, exhibited good thermal stability and repeatability performance. When it was used to catalyze esterification of butanol and acetic acid, the esterification was 99.4% under the optimized reaction conditions: 96°C, butanol 0.12 mol, acetic acid 0.10 mol, cyclohexane 6 mL, catalyst mass fraction 4% in reaction medium and reaction time 3 h. The esterification could reach 74.7% after the catalyst was reused 6 times.