Preparation Of Poly(Ionic Liquid)S And Their Application For Deep Desulfurization Of Fuel Oil

Extraction desulfurization based on ionic liquids is one of the hot research topics in deep desulfurization recently.The extract desulfurization ability of ionic liquids is weak, and small amount of dissoluton or entrainment loss in oil is inevitable, what’s more, the "liquid" features greatly limit the ionic liquid structure modification and designability. As a new kind of adsorbent, poly(ionic liquid)s not only have desulfurization functional groups of the corresponding ionic liquid monomer (imidazolium and pyridinium cations), but also can generate additional physical adsorption with its highly porous structure to achieve the goal of adsorption desulfurization.Therefore, in this paper, four kinds of porous poly(ionic liquid)s were prepared, and their application in removing thiophenic sulfides in model oil was studied.By using 1-vinyl imidazole and 1,4-Bis(chloromethyl) benzene as raw materials, a crosslinked porous poly(ionic liquid) (PIL-1) was synthesized, along with the optimization of synthesis conditions, characterization of its composition and structure, and application for the adsorptive removal of thiophene (T), benzothiophene (BT) and dibenzothiophene (DBT) in model oil. Results show that the optimum synthesis conditions for PIL-1:DMF as solvent, the mole ratio of poly (vinyl imidazole) and 1,4-Bis(chloromethyl) benzene is 2:1 and they are directly mixed reacted under 70℃; The specific surface area of PIL-1 is 99.6 m2·g-1, the average pore size is 16.06 nm which are mainly mesoporous;The desulfurization order of PIL-1 follows the order DBT> BT> toluene-DBT> T; Compared with ethyl imidazole, PIL-1 has a better removability for DBT, BT and T. The adsorption isotherms can be described by Langmuir and Freundlich equation and its saturated adsorption capacity of DBT, BT and T are 7.02、5.15 and 4.08 mgS·g-1 absorbent respectively.We use 1-vinyl imidazole and divinyl benzene to synthesis a series of crosslinked poly(vinyl imidazole)s by varying the mole ratio of reactants, and their adsorption performance for DBT, BT and T in the model oil was tested. On this basis, we use HCl, Chlorobutane and 1,4-Bis(chloromethyl) benzene respectively to react with the copolymer, and get the corresponding poly(ionic liquid)s, i.e. PIL-2, PIL-3 and PIL-4. Characterization was performed with respect to their elemental analysis, morphorlogy, specific area, and thermal stability, and their adsorption performance for different thiophenic sulfurs was studied.The results show that the optimum reaction molar ratio of 1-vinyl imidazole and divinyl benzene is 2:1, and the resulting crosslinked poly(vinl imidazole) (P2) has a wealth of microporous and mesoporous structure with the specific surface area being as high as 675 m2 g-1. In addition, the adsorption performance of P2 for DBT、BT and T is improved greatly compared with 1-ethyl imidazole, which shows that the porous structure plays a vital role in the adsorption desulfurization. The specific surface area of the three kinds of poly(ionic liquid)s have fallen sharply from 675 m2·g-1 to less than 200 m2·g-1 compared to P2, and their adsorption performance on different thiophenic sulfurs changed dramatically! Compared with P2, the adsorptivity of PIL-2 is decreased for DBT and BT, but incresed greatly for T; The above results show that the desulfurization performance of poly(ionic liquid)s is a combinative result of porous physical adsorption and dispersion force and π-π complexation between imidazolium and thiophene ring, and the microporous and mesoporous structure of poly(ionic liquid)s plays a crucial role in adsorption desulfurization.