Preparation And Application Of Polyurethane Pervaporation Membrane For Gasoline Desulfurization

As people pay more and more attention to environmental protection,relevant regulations are increasingly restricting the content of sulfides in motor fuel indicators.The drawbacks of traditional hydrodesulfurization technology,such as high cost and harsh operating conditions,are becoming more and more obvious.It is urgent to develop new alternative technologies.Pervaporation membrane desulfurization technology has received more and more attention due to its mild operating conditions,low operating cost and low octane loss.However,due to the lack of membrane materials with good separation performance and long life,and suitable membrane modules,the industrialization of this technology has been limited.In this thesis,two kinds of fluid catalytic cracking gasoline raw materials named Low sulfur gasoline and high sulfur gasoline were selected,and polyurethane was selected as membrane material.The membrane forming and modification processes were optimized.The membrane's resistance to swelling,life and stability were evaluated.Introducing pervaporation desulfurization into a disc-type membrane module was tentatively explored.The polyurethane membrane was modified by blending polyethylene glycol.The membrane forming processes were optimized.The membrane's microstructure and mechanical behavior were analyzed by infrared spectroscopy,X-ray diffraction,scanning electron microscopy,etc.The desulfurization performance was evaluated by a pervaporation evaluation device to optimize the operating conditions.The results showed that under the optimal film-forming conditions and operating conditions,the permeation flux of the polyurethane membrane to the Low sulfur gasoline was 1.30 kg·m^-2·h^-1,and the enrichment factor was 6.09,the flux to the high sulfur gasoline was 1.27 kg·m^-2·h^-1,the enrichment factor was 3.15.The performance of the membrane achieved a processing target with the flux greater than 1.00 kg·m^-2·h^-1 and the enrichment factor greater than 3.00.The swelling resistance of the prepared polyurethane membrane was tested and its swelling behavior in different gasoline representative components was analyzed.The results showed that the swelling resistance is good.It was also found that the high content of aromatic hydrocarbons and olefins in the raw materials will affect the selectivity of the membrane.The life and stability of the membrane were tested.In the long-term operation of 200 h,the membrane performance was stable and met the requirements of practical application.The products after long-term operation were analyzed,and found that the membrane can further purify thiophene and the possibility of separating aromatics.The membrane separation of high thiophene content was preliminarily explored.When the content of thiophene in the raw material reached 6500?g·g^-1,the flux was still greater than 1.00 kg·m^-2·h^-1,and the enrichment factor was about 3.00.A small disc-tube membrane module made of stainless steel was designed and fabricated.The effect of using the disc-tube membrane module for pervaporation desulfurization was initially explored.When the feed rate was 120 m L·min^-1 and the constant temperature tank temperature was 85?,the permeate flux was 1.64 kg·m^-2·h^-1,and the enrichment factor was3.11.The material selection and research direction of the disc-tube pervaporation membrane module were proposed,which provides a reference for its development.