Study On Desulfurization Of Quaternary Ammonium Salt - Type Gem Surfactant By Phase Transfer Catalytic Oxidation Straight - Run Diesel Oil

The conventional oxidative desulfurization processes has many advantages such as Desulfurization rate high, Mild reaction conditions, Operating costs low and Environmental friendliness, but the two-phase reaction is immiscible and the desulfurization effect is poor. Phase transfer catalysis can facilitate the two-phase contact and finally accelerate the reaction rate by surface activation.In this paper, the quaternary ammonium gemini surfactants are applied in oxidative desulfurization of straight-run diesel based on the problems of oxidative desulfurization and the advantages of phase transfer catalysis.The gemini surfactant as a phase transfer catalyst is applied in oxidative desulfurization of straight-run diesel and is studied in theory.The quaternary ammonium gemini surfactants as the phase transfer catalyst are applied in oxidative desulfurization of straight-run diesel. The gemini surfactant with better desulfurization effect is selected, besides the single factor experiment is carried out. The reaction time, the reaction temperature as well as the amount of Phase transfer catalyst, oxidant and catalyst i.e, are optimized in this paper. Under the best condition of reaction, the sulphur content of straight-run diesel decreased from 304.0 μg/g to 19.0μg/g with desulfurization rate of 93.75% and diesel yield of 93.04%, is up to clear fuel standard of Euro Ⅲ. The best single factors of straight-run diesel desulfurization are C12-2-C12 as a phase transfer catalyst, m(C12-2-C12)/m(straight-run diesel)=0.25%, V(H2O2)/V(straight-run diesel)= 0.3, V(H2O2)/V(CH3COOH)=0.8,70 ℃,1.5 h.The desulfurization rate as the evaluation index is applied in the orthogonal experiment of straight-run diesel oxidative desulfurization with the PTC of C12-2-C12. The reaction time, the reaction temperature as well as the amount of C12-2-C12, oxidant and catalyst are optimized in this paper. The best reaction conditions of the orthogonal experiment are obtained:60℃,2.0 h, m(C12-2-C12)/m(straight-run diesel)=0.3%, V(H2O2)/V(diesel)=0.3, V(H2O2)/V(CH3COOH)=1.0. And the desulfurization rate of straight-run diesel is 95.06% and the sulphur content of straight-run diesel decreases to 15.1 μ/g.From the perspective of phase transfer catalysis, the cycling model of phase transfer catalytic oxidation and the dynamic model are developed on the basis of an insight study of diesel’s oxidative desulfurization by phase transfer catalysis with quaternary ammonium surfactants. There are two steps in the process of phase transfer catalytic oxidation, containing the transfer of oxidative component from water to organic phase and the oxidative desulfurization reaction in the organic phase. A complexation is formed from phase transfer catalytic and oxidative component. It can change the reaction process, lower the apparent activation energy and accelerate the reaction rate, thus the raw material is reduced. From the C12-2-C12’s kinetics study, it shown that the reaction was pseudo first-order reaction with rate constants of kss ℃=0.4759 h-1, k65 ℃=1.0465 h-1 and k75 ℃=0.8224 h-1, and the activation energy Ea=19.38 kJ/mol.