Catalysis Of The Metal Substituted Phosphyotungstic Heteropoly Compounds For Oxidative Desulphurization Of Fuel Oil

With the development of economy, the demand of liquid fuels is increasing. SO_x that generated in combustion of fuels results in acid rain. Moreover it poisons converted catalysts, which cause the environmental pollution. Therefore, in order to enhance the control of environmental pollution, more stringent standard for sulfur content in liquid fuels has been proposed in many countries. Because of high temperature, high hydrogen pressure, highly active catalyst and longer reaction time, the traditional hydrodesulfurization is facing the great challenges. Since the limitation above, it takes a great significance both on theoretical and practical on non-hydrodesulfurization. Above them the non-hydrodesulfurization, oxidative desulfurization is considered one of promising processes for its mild reaction condition, simple equipment design, and highly efficiency. Meanwhile, because of the simple preparation, the high catalytic activity and the environmental protection, heteropoly compound is becoming the hotspot of research and widely used in the area of catalysis.The different metal substituted phosphyotungstic heteropoly compounds were prepared by one-step method with sodium tungstate, disodium hydrogen phosphate, quaternary ammonium salt and then were applied to the experiments of fuel oil oxidative desulfurization by using hydrogen peroxide as oxidant. Copper substituted phosphyotungstic heteropoly compound showed a relatively high catalytic activity. The structures of the compounds were characterized by IR and UV. Reaction conditions on the desulphurization of fuel oil were investigated. The results showed that taking [(C₄H₉)₄N]₄H[PW₁₁CuO₃₉] as catalyst, under the conditions of the dosage of catalyst 4.0% (the mass ratio of catalyst to model oil), the molar ratio of oxidant to oil 2.5 (the molar ratio of effective oxygen in oxidant to the sulfur of oil), the reaction temperature 60℃and reaction time 2h, the sulfur removal rate of model oil 1(A simulated oil 1 consists of model sulfur compound of thiophene and n-octane as solvent) reached 96.78%, under the conditions of the dosage of catalyst 10%, the molar ratio of oxidant to oil 27.5, the reaction temperature 70℃and reaction time 2.5h, the sulfur removal rate of FCC diesel was 60.85%; taking [(C₁₆H₃₃)N (CH₃)₃]₄H[PW₁₁CuO₃₉] as catalyst, under the conditions of the dosage of catalyst 4.0%, the molar ratio of oxidant to oil 4.5, the reaction temperature 70℃and reaction time 2h, the sulfur removal rate of model oil 2(A simulated oil 2 consists of model sulfur compound of benzothiophene and n-octane as solvent) reached 98.39%, under the conditions of the dosage of catalyst 3.0%, the molar ratio of oxidant to oil 22, the reaction temperature 80℃and reaction time 2.5h, the sulfur removal rate of FCC diesel was 65.24%. The outcome realizes that the metal ions substituted phosphyotungstic heteropoly compounds we synthesized show relatively high catalytic activity.