Study On Acidic Ionic Liquids Catalyzed Alkylation Desulfurization Of Fcc Gasoline

To resolve the existed problems of the traditional alkylation desulfurization reaction such as difficult separation of acidic catalyst, serious equipment corrosion and large environment pollution, in this paper, three kinds of acidic ionic liquids catalysts are designed and synthesized. These catalysts are used for catalyzing alkylation desulfurization of model fluid catalytic cracking(FCC) gasoline to achieve environmentally and friendly catalysis. The structures of these ionic liquids are characterized by infrared spectroscopy(IR), H atom nuclear magnetic resonance(1H NMR) and thermogravimetric characterization(TG-DTG). The titration by n-butyl amine is used for the test of acid strength of these ionic liquids. Three green catalytic desulfurization systems are designed and developed including(1) Br?nsted heteropoly acid ionic liquids catalyzed alkylation desulfurization system,(2) Br?nsted-Lewis organic-inorganic heteropoly acid catalyzed alkylation desulfurization system, and(3) acidic-thermoreguated polyether ionic liquids catalyzed alkylation desulfurization system. Three catalytic systems all obtain better desulfurization results.With imidazole, pyridine, chlorinated paraffin, and phosphotungstic acid as raw materials, a series of Br?nsted heteropoly acidic ionic liquids are synthesized, and used for catalyzing alkylation desulfurization of FCC gasoline. The ionic liquids not only show good catalytic activity but also have better performance of recyclability. Among these prepared Br?nsted heteropoly acidec ionic liquids, [Bmim]H2PW12O40 has the highest acid strength and exhibits the best catalytic activity for alkylation desulfurization of FCC gasoline. The effects of the dosage of the catalyst, reaction temperature, and reaction time on the conversions of three thiophenic sulfides catalyzed by [Bmim]H2PW12O40 have been fully investigated. The selected optimal conditions are as follows: the mass ratio of the catalyst to model FCC gasoline 1:100, reaction temperature 125 °C, and reaction time 30 min. Under the optimal conditions, thiophene(T), 2-methyl thiophene(2-MT) and 3-methyl thiophene(3-MT) all can be nearly completely transformed. After the reaction, the catalyst is easily separated from the oil, and can be reused directly. Under the above selected reaction conditions, the catalytic activity of the catalyst [Bmim]H2PW12O40 for the alkylation of three thiophenic sulfides nearly remains unchanged during 12 recycles. For the different sulfides in gasoline including T, 2-MT and 3-MT, the alkylation reaction rate constant(k) and the activation energy(Ea) are tested and calculated. The results show that the order of k is 2-MT > 3-MT > T under the same temperature and the order of Ea is T > 3-MT > 2-MT.With imidazole, 1,3-propanesultone, metal salts, phosphotungstic acid as raw materials, a series of Br?nsted-Lewis organic-inorganic heteropoly acids including an organic imidazolium cation with a sulfonic acid group(-SO3H), a metallic cation, and a heteropolyanion, have been synthesized and used for catalyzing alkylation desulfurization of FCC gasoline. The experiment results have showed that the catalytic activities of the organic-inorganic heteropoly acids mainly have relation with their acid strengths. Among these prepared Br?nsted-Lewis organic-inorganic heteropoly acids, Sm0.33[MIM-PS]HPW12O40 has the highest acid strength and exhibits the best catalytic activity for the alkylation of three thiophenic sulfides including T, 2-MT and 3-MT in model FCC gasolines. The effects of the dosage of the catalyst, reaction temperature, and reaction time on the conversions of three thiophenic sulfides catalyzed by Sm0.33[MIM-PS]HPW12O40 have been fully investigated. The selected optimal conditions are as follows: the mass ratio of the catalyst to model FCC gasoline 1:50, reaction temperature 100 °C, and reaction time 1 h. Under the optimal conditions, T, 2-MT, and 3-MT all can be nearly completely transformed. The recyclability of the catalyst Sm0.33[MIM-PS]HPW12O40 has been investigated. The result has showed that the catalyst exhibits very excellent recyclability. Under the above selected reaction conditions, the catalytic activity of the catalyst Sm0.33[MIM-PS]HPW12O40 for the alkylation of three thiophenic sulfides nearly remains unchanged during 12 recycles.With ethylene oxide, 1,3-propanesultone, dihexylamine, phosphotungstic acid as raw materials, a series of acidic-thermoreguated polyether ionic liquids are synthesized and used for catalyzing alkylation desulfurization of FCC gasoline. The catalytic system has showed the property of miscibility under high temperature and separation under low temperature. So, the ionic liquids exhibit better catalytic performance. [PS-DHA-50]H2PW12O40 has the highest acid strength and exhibits the best catalytic activity for the alkylation of three thiophenic sulfides including T, 2-MT and 3-MT in model FCC gasolines. The effects of the dosage of the catalyst, reaction temperature, and reaction time on the conversions of three thiophenic sulfides catalyzed by [PS-DHA-50]H2PW12O40 have been fully investigated. The selected optimal conditions are as follows: the mass ratio of the catalyst to model FCC gasoline 1:10, reaction temperature 140 °C, and reaction time 3 h. Under the optimal conditions, T, 2-MT, and 3-MT all can be nearly completely transformed. The catalyst reused 5 times and the catalytic activity is almost unchanged.This paper has successfully established three kinds of acidic ionic liquids catalyzed alkylation desulfurization systems. The good desulfurization results are achieved and the catalysts can be efficiently separated and recycled. The paper has provided a new science basis for the application of acid functional ionic liquid in deep alkylation desulfurization. It is important for the basic theory research and the practical application.