| Deep desulfurization of the fuel oil has always been one of the hot research topics of chemical field. Ionic liquids have good extraction performance for thiophene derivatives, yet the problems such as high viscosity, toxicity, and low cost-effectiveness restrict their application in the deep desulfurization of fuel oil. Poly(ionic liquids)(PILs) is a new type of solid materials prepared by polymerization of ionic liquids monomer. This material has the properties of ionic liquids as well as the structural characteristics of polymeric materials, which give PILs a better performance than the ionic liquids monomer. The application of PILs in gas adsorption such as CO2, N2 has been studied a lot, and their use in the absorption of phenol has already been reported. Yet their application in oil desulfurization is rarely available. This paper concentrate on the preparation and functional test of PILs applied for oil desulfurization.In this paper, three PILs have been prepared based on three polymers with different porosity. The first polymer(PCE-1) was prepared by linear polymerization of 4-chloromethyl styrene with 200 degree of polymerization. PIL-1 was prepared by grafting PCE-1 with n-methylimidazole, forming a linear PIL with its functional group content of 0.00316mol·g-1 and decompoaition temperature of ca.200℃. The second polymer substrate (PCE-2) is a commercial crosslinked resin, poly chloride methyl styrene with specific area of 33.19 m2·g-1 and average pore size 14.40 nm. PIL-2 with porous structure is prepared by the grafting PCE-2 with N-methylimidazole. The properties of PIL-2 are as follows:specific area 25.06 m2·g-1, average pore size 9.1 nm. functional group content 0.0029 mol·g-1 and Td= 200℃. PCE-3 was prepared by second modification of PCE-2 using 1,2-ichloroethane via Friedel-Craft reaction. As such, the specific area of PCE-3 is increased drastically to 370.53 m2·g-1 with average pore size 3.83nm. PCE-3 is of microporous structure, and its micropore specific area accounts for half of the total surface area. By reacting PCE-3 with n-methylimidazole, PIL-3 was formed with specific area decreased to 151.79 m2·g-1 the average pore size enlarged to 7.89 nm, Td= 200℃ and imidazolium content of 0.0021 mol·g-1This paper has measured the adsorptive property of three different PILs and PCEs for thiophenic sulfurs. The porous polymer resins PCE-2 and PCE-3 show definite adsorption performance, and their adsorption order is DBT> BT>T, and the adsorptivity of PCE-3 for DBT can be 4.08 mgS·g-1 (25℃, oil/adsorbent mass ratio 50:1). The adsorption performance order of the PILs is opposite to the corresponding polymer resins, i.e. T> BT> DBT, implying that the adsorption mechanism is changed from a physical one to a chemical dominated one. For each sulfide, the adsorptivity of the PILs is closely related to their porosity and specific area, and thus their adsorbance follows the order of PIL-3> PIL-2> PIL-1. The biggest adsorption of PIL-3 for T can be 3.67 mgS-g-1 (25℃, mass ratio of oil and adsorbent 50:1). The result shows that PILs with good desulfurization performance must combine the physical adsorption with chemical adsorption. PILs applying for deep desulfurization should have high specific area and microcellular structure. Besides, the results also show that the adsorption of the PILs can achieve a balance in short time (1h), and the coexist aromatic hydrocarbon in oil can reduce the adsorption quantity of PILs for thiophenic sulfur. |
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