Preparation Of PVA-Solid Acid Catalytic Pervaporation Membrane And Its Study On Synthesis Of Butyl Acetate

A catalytic membrane reactor (CMR) is a unit that acts simultaneously as a separator and a reactor. Combining the reaction and separation in a single stage will simplify the process in accordance to strategy of process intensification and decrease the cost of the equipments. The preparation of pervaporation catalytic membrane was studied using PVA as the separation layer and the solid acid as the catalyst. The manufacture parameters were optimized. And the synthesion of butyl acetate in the CMR was studied.Three prepared methods, such as embedding method, sticking method, and Immersion precipitation phase inversion, were compared for the manufacturing of catalytic pervaporation membrane. Immersion precipitation phase inversion demonstrated the better performance in the catalysis. This method blending the polymer solution with catalyst, and then dipping in the coagulation solution, the catalyst layer forms porous structure. The catalyst activeness is effectively exposed to the membrane surface, and contacted with the reactants adequately, leading to the strongest catalytic activity.The manufacture parameters were optimized for preparing pervaporation catalytic membranes. The best condition was that catalyst loading was 200g/m2, the size of catalyst particle was 200 meshes, and the coagulation bath was ethanol for 25℃. In this condition, there are large holes on the surface of the membrane and the catalytic layer is loose. Meanwhile through the separation experiments for 95% ethanol/water, separation function of pervaporation catalytic membranes showed a flux as 211.95g/(m2-h), and separation factor as 75, which could satisfy the requirement of separation in the reactor.PVA-solid acid catalytic pervaporation membrane was tested in the esterification reactions synthesized butyl acetate. The results show that compared with free solid acid catalyst, the catalytic membrane kept the primary catalytic activity. Through the batch experiment, the optimum reaction conditions were obtained:the catalyst loading was 0.4g, reaction time was 8h. Reaction coupling with separation by the catalytic pervaporation membrane reactor was carried out. In the above reaction conditions, conversion of acetic acid was 91% at 85℃for 20h, while the reaction equilibrium conversion was 75% in the same conditions. It proves that catalytic membrane realized separate coupling with reaction in CMR, and the removal of water broke the equilibrium of reaction, and leading the higher conversion rate.