酸性离子液体中八聚钼酸盐相转移催化氧化脱硫的研究

Phase transfer catalytic oxidative desulfurization of fuels catalyzed by octamolybdate in acidic ionic liquids

制备了四种八聚钼酸盐催化剂:[(C4H9)4N]4Mo8O26,[(C12H25)N(CH3)3]4Mo8O26,[(C14H29)N(CH3)3]4Mo8O26和[(C16H33)N(CH3)3]4Mo8O26。通过元素分析,TG/DSC,FT-IR和紫外-可见光谱等方法对这四种催化剂的组成和结构进行了相应表征。研究了八聚钼酸季铵盐催化剂在酸性离子液体中相转移催化氧化脱硫活性。同时考察了在不同脱硫体系和催化剂、温度(T)、时间(t)、氧化剂(H2O2)用量、催化剂用量、以及酸性离子液体的种类等因素对脱硫效果的影响。经过对反应条件优化,当在70℃下反应3 h,n(H2O2)∶n(DBT)=4∶1,n(DBT)∶n(Catalyst)=10∶1,离子液体[(CH2)3SO3HMIm]BF4用量为1 mL,模拟油品中二苯并噻吩(DBT)脱除率可以达到98.3%,且循环反应6次后催化反应活性没有明显的下降,可以用来进行深度脱硫。最后,对该脱硫体系的脱硫机理进行了讨论。

Four Surfactant-type octamolybdates were synthesized and characterized, and then used as effective catalysts associated with 30% H2O2 as oxidant in the acidic ionic liquid,which has been found suitable for deep removal of organic sulfur in fuels. In this catalytic oxidation desulfurization system, the main factors affecting the desulfurization process include temperature, the reaction time, the dosage of H2O2 and catalyst, as well as the type of acidic ionic liquids. All these factors played significant roles in desulfu- rization efficiency, under the favorable conditions. The sulfur removal could reach almost 98. 3% , which was much better than desul- furization performance by simple extraction with acidic ionic liquid. Moreover,this acidic ionic liquid can be recycled six times by distillation without obviously decrease in activity. Meanwhile, the mechanism of oxidation desulfurization was also elaborated.