The Preparation Of Composite Catalytic Membranes And The Study Of Their Mass Transfer Performance

Pervaporation catalytic membrane reactor (Pervaporation Catalytic Membrane Reactor, PVCMR) is one kind of process intensification technology, which coupling the pervaporation membrane separation processes and catalytic reactions processes. Products could be in situ removed by pervaporation catalytic membrane which combining separation and reaction. As the result, the mass transfer resistance of separation could be reduced and separation efficiency could be improved greatly by pervaporation catalytic membrane, which has drawn an increasing attention by more and more researchers recently.The structure of composite catalytic membrane is too much compact, which cause the low permeability. In this regard, a new catalytic layer which structure is more loose and porous was developed. The mass transfer resistance of different membrane reactors and their effect on the pervaporation-esterification performances was study.In this research, polyvinyl alcohol (PVA) was used as membrane materials, Zr(SO4)2·4H2O was used as catalyst, and the porous PVA catalytic layer was prepared by immersion phase inversion method. The effect on the pervaporation performance of PVA composite catalytic membrane of different types of pore formers (PVP, PEG and LiCl), concentration of pore former, concentration of PVA and the temperature of coagulating bath were study. The topography and the chemical properties of resulted membrane was characterized by SEM and TG. The lose of catalyst and the porosity of the resulted membrane were also study. All reaction components in the reactor was real-time monitored by the gas chromatography.The structure of PVA catalytic layer was net-like and porous when PVP was used as the pore former. The optimum membrane preparation condition was showed as below:10 wt.% PVA,1.0 wt.% PVP and the temperature of coagulating bath was 40?. The catalyst of PVA catalytic layer was lost below 3%, which was immersed in n-butanol for 7 days. The porosity of PVA catalytic layer was 80%. When the concentration of water in the membrane reactor was increased from 5wt.%to 9wt.%, the water flux was increased from 183 g·m2·h to 441 g·m2·h, while the separation factor was decreased from 436 to 356. After 29 hours of pervaporation-esterification process, the concentration of water in the PVA composite catalytic membrane reactor with porous catalytic layer was almost 0, while the concentration of water in the PVA composite catalytic membrane reactor with dense catalytic layer and the PVA separation membrane reactor was 0.758 mol/L and 1.02 mol/L, respectively.