POSS-hybrid membranes for the removal of sulfur aromatics by pervaporation

Abstract

Membrane-based separations are a promising attempt for desulfurization of fuels in petrochemical industry. The focus on research is to investigate membranes, which are more efficient and show better separation characteristics. Hybrid membranes made of an organic polymer and inorganic compounds combine both in one material and new properties can be realized. Here new hybrid membranes of polyimides and POSS (polyhedral oligomeric silsesquioxane) compounds for desulfurization by the membrane-based separation process pervaporation were investigated. The POSS compounds can act as cross-linking agent between polymer chains through reactive organic side groups, resulting in improved membrane properties.In pervaporation experiments the behavior of glycidyl-POSS hybrid membranes with different amount of POSS as additives have been analyzed for a binary mixture consisting of benzothiophene and n-dodecane in comparison to a native copolyimide membrane. Thereby the concentration of benzothiophene has been varied. The hybrid membranes showed lower fluxes due to cross-linking, correlating with PALS and WAXD results. At higher temperatures also higher selectivity is found. Furthermore in stress strain measurements the glycidyl-POSS hybrid membranes showed improved properties in comparison to a native membrane.