High Catalytic Performance of MoO3-Bi2SiO5/SiO2 for the Gas-Phase Epoxidation of Propylene by Molecular Oxygen

Authors

  • Yijun Pang,

    1. National Engineering Research Center for Chemical Fertilizer Catalyst, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350002 (P.R. China), Fax:(+86) 591-83738808
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  • Prof. Xiaohui Chen,

    Corresponding author
    1. National Engineering Research Center for Chemical Fertilizer Catalyst, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350002 (P.R. China), Fax:(+86) 591-83738808
    • National Engineering Research Center for Chemical Fertilizer Catalyst, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350002 (P.R. China), Fax:(+86) 591-83738808

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  • Dr. Chengzhi Xu,

    1. National Engineering Research Center for Chemical Fertilizer Catalyst, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350002 (P.R. China), Fax:(+86) 591-83738808
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  • Yangjun Lei,

    1. National Engineering Research Center for Chemical Fertilizer Catalyst, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350002 (P.R. China), Fax:(+86) 591-83738808
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  • Prof. Kemei Wei

    1. National Engineering Research Center for Chemical Fertilizer Catalyst, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350002 (P.R. China), Fax:(+86) 591-83738808
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Abstract

MoO3-Bi2SiO5/SiO2 catalysts with a Mo/Bi molar ratio of 5, prepared by a two-step hydrothermal and simple impregnation method, were investigated for the epoxidation of propylene by O2 and characterized by XRD, N2 absorption–desorption isotherms, thermogravimetric analysis (TGA), temperature-programmed reduction, NH3 temperature-programmed desorption (TPD), and IR, Raman, and X-ray photoelectron spectroscopy (XPS). On MoO3-Bi2SiO5/SiO2 with Mo/Bi=5 calcined at 723 K, a propylene conversion of 21.99 % and a propylene oxide selectivity of 55.14 % were obtained at 0.15 MPa, 673 K, and flow rates of C3H6/O2/N2=1/4/20 cm3 min−1. XRD, IR spectroscopy, and XPS results show that Bi2SiO5 and MoO3 are crystalline nanoparticles. NH3-TPD results indicate that the surface acid sites are necessary for the high catalytic activity. The results of TGA and N2 absorption–desorption isotherms reveal that a reasonable calcination temperature is 723 K. The reaction mechanism of propylene epoxidation on MoO3-Bi2SiO5/SiO2 catalysis is hypothesized to involve an allylic radical generated at the molybdenum oxide species and the activation of O2 at the bismuth oxide cations.

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