Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (10): 2416-2420.doi: 10.3866/PKU.WHXB20110934

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Dispersion States and Brønsted Acidity Feature of Nb2O5on t-ZrO2

HE Jie1,2, FAN Yi-Ning2   

  1. 1. School of Chemical Engineering, Anhui University of Science and Technology, Huainan 232001, Anhui Province, P. R. China;
    2. Key Laboratory of Mesoscopic Chemistry of MEO, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
  • Received:2011-05-16 Revised:2011-07-07 Published:2011-09-27
  • Contact: HE Jie
  • Supported by:

    The project was supported by the National Key Basic Research Program of China (G1999022400) and National Natural Science Foundation of China (21071004).

Abstract: Nb2O5/t-ZrO2 catalysts with different loadings were prepared by aqueous solution impregnation using niobium oxalate as a precursor on tetragonal ZrO2 (t-ZrO2). The dispersion states with respect to niobia species on t-ZrO2 were characterized by powder X-ray diffraction (XRD), laser Raman spectroscopy (LRS), and UV visible diffuse reflectance spectroscopy (UV-Vis DRS). The catalytic activity was evaluated by the condensation reaction of iso-butene (IB) and iso-butyraldehyde (IBA) to 2,5-dimethyl-2,4-hexadiene (DMHD) and the Brønsted acidity was evaluated by the Fourier-transform infrared spectroscopy of pyridine adsorption (Py-IR). The results reveal that the dispersion capacity ΓNb of Nb2O5 on t-ZrO2, which was determined by XRD quantitative phase analysis, is almost identical to the value predicted by the "incorporated model". The results also show that the Brønsted acid sites are strongly related to the states of Nb2O5 on Nb2O5/t-ZrO2.

Key words: Nb2O5, t-ZrO2, Surface dispersion state, Surface acidity feature, Olefin-aldehyde condensation


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