Propane Aromatization over Mo／HZSM—5 Catalysts

Impregnation,mechanical mixing and hydrothermal treatment methods were used to introduce molybdenum species into the HZSM-5 zeolite ,the structure and surface acidity of the catalysts were studied by means of XRD,FT-IR ,NH3-TPD,TPR and XPS,The effects of Mo content and reaction time on stream on the aromatization of propane were investigated,It was found that the performance of the Mo/HZSM-5 catalst prepared by the hydrothermal treatment method was much better than that of the other two catalysts,For example ,under the reaction conditions of 823 K and 600h^-1, propance conversion and aromatics selectivity over the catalyst prepared by hydrothermal pretreatment could reach 89.17% and 78.56%,respectively,XRD and XPS results showed that the Mo species in the catalysts prepared by hydrothermal treatment were highly dispersed on the surface of the HZSM-5,and lartger amounts of them could penetrate into the HZSM-5 channel ,as compared with the other two kinds of catalysts,These factors may be responsibled for their high activities for propane aromatization,IR and NH3-TPD studies indicated that the number of Broensted acid centers decreased and the Lewis acid centers increased after Mo was introduced into the HZSM-5 zeolite.

Propane Aromatization over Mo/HZSM-5 Catalysts

Impregnation, mechanical mixing and hydrothermal treatment methods were used to introducemolybdenum species into the HZSM-5 zeolite. The structure and surface acidity of the catalysts werestudied by means of XRD, FT-IR, NH3-TPD, TPR and XPS. The effects of Mo content and reaction timeon stream on the aromatization of propane were investigated. It was found that the performance of theMo/HZSM-5 catalyst prepared by the hydrothermal treatment method was much better than that of theother two catalysts. For example, under the reaction conditions of 823 K and 600 h-1, propane conversionand aromatics selectivity over the catalyst prepared by hydrothermal pretreatment could reach 89.17%and 78.56%, respectively. XRD and XPS results showed that the Mo species in the catalysts preparedby hydrothermal treatment were highly dispersed on the surface of the HZSM-5, and larger amounts ofthem could penetrate into the HZSM-5 channel, as compared with the other two kinds of catalysts. Thesefactors may be responsible for their high activities for propane aromatization. IR and NH3-TPD studiesindicated that the number of Bronsted acid centers decreased and the Lewis acid centers increased afterMo was introduced into the HZSM-5 zeolite.