Preparation of a Silica Gel Confined Ionic Liquid and Its Use as Catalyst for Esterification

To decrease the amount of ionic liquid and facilitate the separation of catalyst from the product,a novel silica gel confined ionic liquid [Hmim]TsO catalyst was prepared with sol-gel method.The catalyst was characterized by DRFITS,FT Raman and BET.Results show that the ionic liquid is confined on silica gel and the specific area of the catalyst is about 51.15 m2/g.It was used in the synthesis of n-butyl acetate,and the optimized reaction conditions were:reaction temperature 95 ℃,mole ratio of n-butanol to acetic acid 1.2∶1,ionic liquid mass fraction 5.6% in reaction medium,and reaction time 6 h.The yield of n-butyl acetate was 94%.Compared with catalysis by ionic liquid [Hmim]TsO,the yield of n-butyl acetate increases by 8.9% and ionic liquid mass amount is reduced by 72%.The [Hmim]TsO/silica gel 〔w([Hmim]TsO)=62%〕 catalyst can be separated easily,and the yield still reaches 83.3% after reused 6 times.