Study On Preparation And Desulfurization Performance Of Surface Modified Pervaporation Membrane

As a new gasoline desulfurization technology,pervaporation desulfurization technology has good industrial application prospects due to its advantages of low equipment investment,low operating conditions,no damage to the octane number in gasoline,and sulfide can be recycled and reused.The key to the pervaporation desulfurization technology is the membrane material and membrane preparation.During membrane preparation,modification and optimization of membrane is the important way to improve membrane separation performance.At present,in the field of pervaporation membrane desulfurization,the modification methods of pervaporation membrane materials are mainly to modify the membrane material body,there are few related studies on the surface modification of membrane materials.Therefore,this paper used surface modification methods to modify membrane materials,explored the effect of membrane Surface polarity and membrane surface morphology on pervaporation desulfurization performance,and improved the performance of pervaporation desulfurization through surface modification.In this thesis,using the biomimetic mussel properties of dopamine（DA）,dopamine was deposited on the surface of polyurethane（PU）to prepare the PDA-PU membrane material to explore the effect of membrane surface properties on the pervaporation performance.The membrane before and after modification was characterized by infrared spectroscopy,scanning electron microscope,contact angle meter,and atomic force microscope,and the desulfurization performance of the membrane was evaluated by a pervaporation evaluation device.By changing the thickness of the polyurethane membrane,the position of dopamine deposition,the time of dopamine deposition,it was concluded that the polarity of the membrane surface increases,which improves the selective solubility of thiophene on the membrane surface,and the enrichment factor was increased by 57%after dopamine modification.In addition,polyurethane belongs to the dissolution control in the"dissolution-diffusion"model,surface polarity has an important influence on the pervaporation desulfurization performance of polyurethane.In this paper,two silane coupling agents were used to modify the surface of the PU membrane.By adjusting the surface microstructure of the membrane,the purpose of improving the membrane pervaporation desulfurization performance was achieved.The membrane before and after modification was characterized by infrared spectroscopy,scanning electron microscope,contact angle meter,and atomic force microscope,and the desulfurization performance of the membrane was evaluated by a pervaporation evaluation device.The surface morphology of the membrane changes after silane coupling agent modification,and a non-penetrating gully structure appears on the surface of the membrane.This surface morphology effectively reduces the mass transfer resistance,increases the effective membrane area,and has a positive impact on the increase in flux.After surface modification ofγ-methylpropyloxy propyltrimethoxy silane（KH570）the flux reached 2.50kg·m^-2·h^-1,the enrichment factor was 7.01,the flux increased by 164%,and the enrichment factor decreased by 29%.After surface modification of hexadecyltrimethoxysilane（HDTMS）,the flux was 2.92 kg·m^-2·h^-1,the enrichment factor was 6.01,the flux was increased by 208%,and the enrichment factor was reduced by 34%.The modified membrane was subjected to a100 h long-period operation experiment,the performance of the membrane was stable and it has the potential for long-term stable operation..