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

doi:10.11944/j.issn.1000-0518.2018.11.170462

摘要/Abstract

摘要：

采用溶胶凝胶法合成了钛硅纳米复合氧化物(TiO₂-SiO₂),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 mL,反应温度60 ℃,催化剂质量0.15 g,n(H₂O₂)∶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10.0 μg/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。

关键词: 磷钼酸, 钛硅纳米复合氧化物, 氧化脱硫, 溶胶凝胶法, 过氧化氢

Abstract:

High-performance titania-silica(TiO₂-SiO₂) nanocomposites were synthesized with a sol gel method. The composite catalyst was prepared by either in situ synthesis(HPMo-TiO₂-SiO₂-is) or the impregnation method(HPMo/TiO₂-SiO₂) using Keggin-structure phosphomolybdic acid and TiO₂-SiO₂. 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-TiO₂-SiO₂-is and HPMo/TiO₂-SiO₂ 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-TiO₂-SiO₂-is and HPMo/TiO₂-SiO₂ are similar under optimized conditions. The conversion of dibenzothiophene is 96.0% and the content of sulphur is below 10 μg/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-TiO₂-SiO₂-is catalyst is almost as the same as that of freshly prepared. The HPMo-TiO₂-SiO₂-is and HPMo/TiO₂-SiO₂ catalysts could be recycled and easily separated. These catalysts used herein are an ideal model for oxidation desulfurization of sulfur compounds.

Key words: phosphomolybdic acid, titania-silica nanocomposite, oxidative desulfurization, Sol Gel method, hydrogen peroxide

刘迪,佟欢,袁琳杰,张子鹏,马康富,远琳,张婉钰,陈立东,王祥生,郭洪臣. 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[J]. 应用化学, 2018, 35(11): 1351-1356.

LIU Di,TONG Huan,YUAN Linjie,ZHANG Zipeng,MA Kangfu,YUAN Lin,ZHANG Wanyu,CHEN Lidong,WANG Xiangsheng,GUO Hongchen. Preparation of High Activity Oxidative Desulfurization Catalyst from Phosphomolybdic Acid and Titania Silica Nanocomposite[J]. Chinese Journal of Applied Chemistry, 2018, 35(11): 1351-1356.

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