Preparation And Characteristics Of Silica Surface Molecularly Imprinted Polymer For Gasoline Desulfurization

Using the surface molecular imprinting technique, a kind of polymer for sulfur removal from gasoline was synthesized and characterized, the changes of binding energy between template molecules,functional monomers and polymers in different conditions were computed with molecular simulation software.Grafted onto silica gel surface modified withγ-aminopropyltriethoxy silane and methacrylic acid, a molecularly imprinted polymer (MIP) for selective benzothiophene recognition was synthesized with crylic acid as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent in the presence of benzothiophene as the template molecule. Textural characterization of MIP was carried out with FT-IR, elemental analysis and N2 adsorption, the static adsorption properties were described via benzothiophene-containing simulated gasoline.The results showed that a porous molecular imprinted polymer layer with its thickness of 5 nm was successfully grafted onto carrier silica gel surface. The adsorption capacity of MIP for benzothiophene reached 57.4 mg/g, in comparison with 38.7 mg/g of non-molecular imprinted polymer (NMIP). MIP exhibited higher adsorption capacity and better selectivity for benzothiophene than that of NMIP. Its adsorption behavior met Langergren quasi-two kinetic equation and belonged to monolayer molecular adsorption fitted well to Langmuir isotherm equation. After many times of regeneration, the adsorption capacity of MIP almost kept unchanged, which illustrated that MIP could be reused.A composite molecularly imprinted polymer was also synthesized on silica gel surface in the coexistence of thiophene,3-methyl-thiophene, benzothiophene and dibenzothiophene as template molecules. Its dynamic adsorption was conducted in both real gasoline and simulated gasoline.The results showed that MIP dynamic saturated adsorption capacities for thiophene,3-methylthiophene, benzothiophene and dibenzothiophene in simulated gasoline were 24.56 mg/g. 22.2 mg/g,33.82 mg/g and 34.85 mg/g respectively. Whereas in real gasoline, its sulfur capacity was 12.56 mg/g, namely its adsorption capacity for sulfur compounds was approximately 43.2 mg/g.Molecular simulation software Materials Studio4.4 was employed to compute the binding energy between template molecular, functional monomer and MIP. The simulation results were basically consistent with the above conducted experiments, which showed that molecular simulation technique could be used to cast about for polymer materials selection and dosage determination expediently and economically.