磷钨酸/纳米晶TS-1催化剂高效择形催化氧化脱硫

EFFICIENT SHAPE-SELECTIVE OXIDATIVE DESULFURIZATION BY PHOSPHOTUNGSTIC ACID/NANOCRYSTALLINE CATALYST TS-1

采用浸渍法合成了纳米晶TS-1负载磷钨酸的HPW-Nano-TS-1催化剂,31PMAS-NMR,FT-IR,UV-vis表征结果表明,合成的负载型催化剂上磷钨酸保持Keggin骨架结构。以模型有机硫化物的正辛烷溶液为模拟油的吸附脱硫试验结果表明,噻吩、苯并噻吩和二苯并噻吩在纳米晶TS-1及HPW-Nano-TS-1样品上吸附达到平衡的时间逐渐增加,饱和吸附量相应减少。磷钨酸的引入提高了纳米晶TS-1对于大分子有机硫化物二苯并噻吩的氧化脱除活性。在温度60℃的反应条件下,噻吩的脱除率高于98.0%,二苯并噻吩的脱除率为58.0%,3种模型有机硫化物氧化脱除由易到难的顺序为:噻吩>二苯并噻吩>苯并噻吩,与常规的TS-1沸石或者多酸催化剂的活性顺序存在明显的差异,这是纳米晶TS-1沸石对于有机硫分子氧化反应的择形作用、扩散效应和磷钨酸在催化氧化脱硫过程中的电子云密度综合作用的结果。

The catalyst(HPW-Nano-TS-1) with phosphotungstic acid ( HPW) supported on nanocrystalline TS-1 was synthesized by impregnation method.The results of31 P MAS-NMR,FT-IR and UV-VIS characterization indicated that the preservation of the Keggin structure in HPW-Nano-TS-1 catalysts was confirmed.Catalytic oxidative desulfurization reaction and adsorption desulfurization over synthesized catalysts with model oil consisting of n-octane solution of organic sulfur was investigated.The time for the adsorption of thiophene,benzothiophene and dibenzothiophene over the nanocrystalline TS-1 and HPW-Nano-TS-1 samples gradually increased, and the saturated adsorption amount decreased accordingly.The introduction of HPW enhances the oxidative removal activity of nanocrystalline TS-1 for macromolecular dibenzothiophene.The removal rates of thiophene and dibenzothiophene were 98.5% and 58.0% at 60 ℃,respectively.The order of removal of organic sulfide in the three models from easy to difficult is:thiophene > dibenzothiophene > benzothiophene,clearly different in the order of easy removal of benzothiophene from conventional microporous zeolite or polyoxometalate catalysts.It is due to the effects of shape- selectivity,diffusion effect as well as the electron cloud density of nanocrystalline TS-1 zeolite and HPW on the oxidation reaction of organic sulfur molecules.