磷钼酸和钛硅纳米复合氧化物构筑高活性氧化脱硫催化剂

Preparation of High Activity Oxidative Desulfurization Catalyst from Phosphomolybdic Acid and Titania Silica Nanocomposite

采用溶胶凝胶法合成了钛硅纳米复合氧化物(Ti O_2-Si O_2),并以其为载体用原位合成技术或浸渍法负载Keggin结构磷钼酸(HPMo)制备了复合催化剂,使用扫描电子显微镜(SEM)、傅里叶红外光谱仪(FT-IR)、紫外可见光谱仪(UV-Vis)、X射线衍射光谱(XRD)和比表面分析仪(BET)等测试手段对催化剂的结构进行表征。结果表明,采用原位法合成的催化剂为纳米粒子,纳米晶骨架内存在微孔和介孔共存的孔道结构。原位合成技术或浸渍法制备的催化剂中HPMo保持Keggin骨架结构。以模拟油品(二苯并噻吩、苯并噻吩或噻吩的正辛烷溶液)的氧化脱硫为探针反应,在选定的条件下:硫含量为200.0 g/g的正辛烷溶液和无水乙醇各10.0 m L,反应温度60℃,催化剂质量0.15 g,n(H_2O_2)∶n(S)=5∶1,二苯并噻吩的脱除率高于96.0%,产物中硫含量低于10.0μg/g。在相同的实验条件下,受电子云密度的影响,脱硫由易到难的顺序为二苯并噻吩>苯并噻吩>噻吩。催化剂循环使用4次后活性未见明显降低,是一类绿色的模型有机硫化物氧化脱除工艺用催化剂。

High-performance titania-silica(TiO 2-SiO 2)nanocomposites were synthesized with a sol gel method.The composite catalyst was prepared by either in situ synthesis(HPMo-TiO 2-SiO 2-is)or the impregnation method(HPMo/TiO 2-SiO 2)using Keggin-structure phosphomolybdic acid and TiO 2-SiO 2.The structures of these catalysts were characterized by scanning electron micrographs(SEM),Fourier transform infrared spectrum(FT-IR),ultraviolet visible spectroscopy(UV-Vis),Brunauer-Emmett-Teller(BET)and X-ray powder diffraction pattern(XRD).The preservation of the Keggin structure in HPMo-TiO 2-SiO 2-is and HPMo/TiO 2-SiO 2 catalysts was confirmed.The results show that the synthesized catalysts are in nanometer size and the micropores and mesopores coexist.The catalytic oxidation desulfurization reaction was studied over synthesized catalysts with a model oil(n-octane solution of organic sulfur).Reaction conditions are listed as following:model oil/ethanol=10.0 mL/10.0 mL,catalyst 0.15 g,n(O)/n(S)=5,temperature 30~70℃and time=3 h.It is clear that the catalytic properties of the HPMo-TiO 2-SiO 2-is and HPMo/TiO 2-SiO 2 are similar under optimized conditions.The conversion of dibenzothiophene is 96.0%and the content of sulphur is below 10μg/g.Under the same conditions,the efficiencies of oxidative desulfurization decrease in the order of dibenzothiophene>benzothiophene>thiophene,and the result is influenced by the electron density on the sulfur atoms.The catalytic activity of the recycled HPMo-TiO 2-SiO 2-is catalyst is almost as the same as that of freshly prepared.The HPMo-TiO 2-SiO 2-is and HPMo/TiO 2-SiO 2 catalysts could be recycled and easily separated.These catalysts used herein are an ideal model for oxidation desulfurization of sulfur compounds.