Preparation Of The Hollow Fiber Membrane With Efficient Catalytic-separative In Situ And Study On Membrane Reaction Process

Recovery of perfluorosulfonic acid resin (PFSA) were conducted by regeneration and dissolution of the derteriorated perfluoro-ion-exchange membrane (PFIEM) in chlor-alkali industry. Moreover, the recovered PFSA was mixed with PVA to prepare PVA-PFSA/PVA-PFSA/PAN catalytic hollow fiber composite membranes using the hollow fiber ultrafiltration membrane of polyacrylonitrile (PAN) as the support layer.Firstly, different preparation methods were explored to prepare the PVA-PFSA/PVA-PFSA/PAN hollow fiber composite membrane. Then, the influence of different preparation methods of membrane on membrane structure and properties and the relationship between structure and materials of membranes and their catalytic performance and the permeability were studied. By dip-coating method the separation-function hollow fiber composite membranes (SMs) were fabricated. PVA-PFSA/PAN membranes were dense and smooth, which were applied to the pervaporation process. The effects of different perfluorosulfonic acid (PFSA) concentrations on SMs and different heat treatment temperature were investigated. Then, by non-solvent induced phase separation (NIPS) method the CM was prepared by casting PVA-PFSA catalytic solution on the top layer of SM. CMs had porous structure resulting in small mass transfer resistance and good catalytic effect. Separation performance of Composite membrane was influenced deeply by heat treatment. With heat treatment temperature increasing the composite membrane permeation flux declined and the separation factor increased. In addition, along with the increase of PVA content in the coating liquid, the separation of water/ethanol factor increased then fell, however permeate flux dropped. In esterification reaction, the reaction temperature played a great role on the ethanol conversion and reaction rate:with the temperature decreased, the reaction rate was smaller and the ethanol conversion rate was smaller.Secondly, based on the prepared hollow fiber composite membranes, the separative layer and the catalytic layer were optimized to improve separation performance and catalytic properties of PVA-PFSA/PVA-PFSA/PAN hollow fiber composite membranes at the same time. The separation performance was measured by the dehydration of n-butanol/H2O mixtures while the catalytic activity was tested by the esterification reaction of acetic acid and n-butanol. The FESEM showed composite membranes was well combined with PAN substrate. The separative layer fabricated by dip-coating method was dense while the catalytic layer prepared by non-solvent induced phase separation method were coarse and porous. The result showed that with PFSA content increasing, the permeate flux increased while the separate factor decreased gradually. With heat treatment temperature increasing the composite membrane’s permeation flux declined and the separation factor increased. As the temperature of feed liquid increased from50℃to80℃, the permeation flux increased gradually and the separation factor increased slightly. The results of the experimental of catalytic esterification showed that the composite catalytic membrane with porous catalytic layer had better catalytic effect, bigger reaction rate than dense membranes. With the increase of PFSA mass fraction, the reaction rate accelerated, and butanol conversion rate was higher.Lastly, the appropriate composite membranes with the best separation performance and catalytic effect were selected from the prepared PVA-PFSA/PVA-PFSA/PAN catalytic hollow fiber composite membranes. Then, they were fabricated to membrane module and applied to the coupled esterification-pervaporation process. In the same time, the construction of a membrane reactor was explored.