Preparation And Characterization Of Silica-supported Recovered Perfluorosulfonic Acid Ion-exchange Membrane And Its Application In Catalytic Distillation

As expected due to the fluorocarbon nature of the backbone, perfluorinatedresinsulfonic acids were both chemically stable and thermally stable up to 280~C, atwhich temperature the sulfonic acid groups began to decompose. These materials wereknown to be very strong Bronsted acids. One major drawback of these materials washowever the very low surface area and that the activity of these materials either innon-swelling solvents or in the gas phase was very low. This in tum had limited theutility of these materials.The used perfluorosulfonic acid ion-exchange membrane was treated into asolution of perfluorosulfonic acid resin to recycle the perfluorosulfonic acidresin(PFIEP). The perfluorosulfonic acid resin/silica composite catalysts(NFH) ofdifferent surface areas and polymer contents were prepared using a sol-gel technique,and characterized by FTIR, DSC-TG A, TEM, SEM, BET measurements. Nanometersized PFIEP particles were entrapped within a highly porous silica network. For thesenanocomposites, PFIEP was highly dispersed within and throughout the porous silicanetwork on the tens of nanometers level, the extent of dispersion of PFIEP within theporous silica framework could be altered. This significantly increased the effectivesurface area of PFIEP particles (within the porous silica). Catalyst NFH showed veryhigh activity in the areas of esterification and condensation reactions. Catalyst NFH3was found to be better than Nation SAC-13 for the systhesis of dioctyl phthalate.A novel interval withdraw technique for catalytic distillation was explored for thesynthesis of dioctyl phthalate. The results showed that the technique was more efficientthan the conventional process.