The Preparation Of Hollow Fiber Composite Membrane For Olefins And Paraffins Separation

Separation process using membranes has been considered as one of the most potential processes because of the superiorities such as the low-energy costing, easily operation , high efficiency and lower costs etal. Nowadays, more and more attentions have been paid on separation process of olefins and paraffins by using gas separation membranes' technique.Two kinds of novel polyarylene ether such as PPES and PPEK are synthesized by professor Jian Xi Gao of Dalian university of technology. PPESK is synthesized by polycondensation based on 4-(4-hydroxyphenl)-2,3-phthalazine-l-one(DHPZ) and diflorodiphenyl keton or dichloro diphenyl sulphone as the monomers, respectively. The glass transition temperature of two kinds of polymers are 263℃ and 305℃, respectively. PPESK showed both excellent comprehensive performances and high heat-resistances, better than the other dissoluble engineering plastics. A kind of hollow fiber composite membrane for olefins and paraffins separation has been prepared by using PPESK.First, constrctures and performance of the PPESK hollow fiber membranes prepared based on the phase separation behavior of PPESK dope by phase inversion methods has been systemically researched. The influences of the casting components, concentrations of polymer, contiguity factors of casting, the temperature of gel-bath and casting, air gap of the dry/wet spinning process, the proportions of THF and EtOH, the temperatrue and pressure of the operation has been systemically studied.Second, with the dip-coating method, the hollow fiber composite membrane has been prepared. The separation of the propane and propylene is generating due to the dissolve -diffusion process.Under the different conditions: silicon rubber's contents, the pressure and time of coating, pre-treatments of the composite membranes and operational factors, the performances of the composite membranes are different. The regularities is systemtically researched.The end, it is found that coating water-soluble polymer such as PVP or PEO can make the uniform of layer much thinner. As a result, a thinnest-layer coating hollow fiber polymer electrolyte composite membrane has been successfully prepared by using dip-coating method coated PVP mixed Ag~+. The influences of PVP concentration, proportion of Ag~+ and C=O, operational pressure and temperature, types of transition metals were systemically studied using the SEM, IR techniques.