For the process of terephthalic acid production,acetic acid dehydration refers to the separation of water-the by-product,from the reaction medium (acetic acid),and the recycle of acetic acid.Because the water/acetic acid binary system has tangent pinch on the pure water end,the separation of water from acetic acid willconsume a lot of energy [1].Thus,it is more customary to use alkyl acetates,such as isobutyl acetate,n-butyl acetate,n-propyl acetate etc.,as entrainer througha heterogeneous azeotropic distillation system for the separation.However,these azeotropic agents have disadvantages including accumulation of p-xylene,pollution of bottom product of dehydration colunm and so on [2].P-xylene,which could form a minimum-boiling point azeotrope with water,is a reactant itself,and consequently can overcome the shortcomings mentioned above [3-5].