Kinetics and mechanism of plasma oxidative desulfurization in liquid phase

Factors affecting the plasma oxidative desulfurization of organic sulfides in the liquid phase were investigated. The organic sulfides, including merc aptan, thioether, and thiophene, are mixed with n-heptane severally or join tly. The plasma power load, i.e., the ratio of oxygen flow to plasma power, and the reaction time are the primary factors affecting the desulfurizatio n reaction when the reaction temperature was controlled at about -85 degree sC. Under suitable conditions, the degree of desulfurization for mercaptan, thioether, thiophene, and/or their mixtures can exceed 99%, 80%, 79%, and 88%, respectively. On the basis of the conception that the electron energy function f(epsilon) and the molar ratio of the reactants R control the reac tion rate and the product composition, a kinetic model was developed to des cribe the plasma oxidative desulfurization reaction in the liquid phase usi ng macroscopic test parameters. The good agreement of the calculated result s with the experimental data indicates that the plasma reaction in the liqu id phase is essentially the gaseous reaction occurring under special condit ions. The normal viewpoint that the reaction takes place between energetic electrons and the surface molecule of the liquid may be incorrect. The reac tion mechanism for plasma oxidative desulfurization of mercaptan, thioether , and thiophene in the liquid phase is discussed.