The Study On The Catalysts Of Heteropoly Acids Supported On The Molecular Sieves For The Hydrodesulfurization

The catalysis of heteropoly acids (HPA) in solid state has received much attention owingto their unique acidic and redox activities. Nanocrystalline HZSM-5zeolites (nano HZSM-5)are thought to be an ideal material for the encapsulation of HPA molecules having a Kegginstructure since they have the intergranular secondary pore.However, The ordered mesoporouszeolites materials incorporated with polyoxometalate for the hydrodesulfurization (HDS)research has not been reported.In this paper, Keggin or Dawson structure of HPA and Ni (II) components were loadedon nano HZSM-5zeolite to prepare the phosphomolybdic acid (PMo)/nanometer HZSM-5solid acid catalyst by impregnating technology, the HDS activity of nanometer HZSM-5zeolite, olefin reduction activity and aromatization properties, and the stability of the catalyticactivity were all improved. According to the FT-IR, XRD, SEM and TEM of catalystscharacterization results, it shows that the active component of load highly dispersed on thesurface of the carrier, and the particle is very small; From the TG of the catalysts, we canknow that, the thermostabilization temprature of the HPA in solid acidic catalysts is closed to400oC, they can be used as the HDS catalysts of FCC gasoline.In this paper, based on FCC gasoline HDS reaction as the probe reaction, evaluation ofthe activity of catalyst. Under the selected conditions, Sulfur content in crude oil reducedfrom250μg/g to around10μg/g, aromatic content increased from18.0vol%to25.0vol%,olefin content decreased from35.0vol%to below10.0vol%, the product is accord with theIV standard of clean gasoline. At the same time,we discussed the influence of differentstructure HPA and carriers for catalytic reaction. Finally concluded that the HZSM-5is withwell-organized mesoporous structure, high specific surface area and strong acidity, HPA andNi (II) components loaded on it could improve the HDS reaction activity and selectivity (>95%), so it is a kind of good support of the desulfurization reaction.Try to mix the sandwich or absence type polyoxometalates (HPA) in the process ofsynthying the mesoporous molecular sieve MCM-41, and got a new kind of HPA/MCM-41mesoporous hybrid materials HPA is in hole wall of mesoporous materials with the covalent union. According to the FT-IR, XRD, SEM and TEM of catalysts characterization results, itshows that Not only the the sandwich type or absence type structure of HPA is still retained,and tend to be saturated, the sample is still hexagonal symmetrical, and the size ofmesoporous channel is uniform. According to FCC gasoline hydrodesulfurization (HDS)reaction as the probe reaction, it shows that the mesoporous hybrid materials has a certainHDS activity.