Acta Phys. -Chim. Sin. ›› 1994, Vol. 10 ›› Issue (02): 114-120.doi: 10.3866/PKU.WHXB19940205

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Characterization of Acid-Base Property of ZrO2 by Thermal Desorption: II. Dual Adsorption of NH3 and CO2

Xu Bai-Qing, Yamaguchi Tsutomu, Tanabe Kozo,  Liang Juan, Zheng Lu-Bin   

  1. Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian 116012| Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060, Japan; Dalian Institute of Chemical Physics, Academia Sincia, Dalian 116023
  • Received:1992-05-18 Revised:1993-04-23 Published:1994-02-15
  • Contact: Xu Bai-Qing

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Abstract:

Dual adsorption of NH_3 and CO_2 has been used to study the acid property of ZrO_2 in relation to its base property by TPD and IR spectroscopy. It is found that preadsorbed NH_3 (or CO_2) has no inhibitory but a promotive effect to a postadsorption of CO2 (or NH_3). The increased adsorption of the postadsorbed moecules is most pronounced in the TPD curves at above 510 K. In the IR observation, the dual adsorption effect is characterized by a formation, on one hand, of a monodentate carbonate species which can not be formed in the single adsorption of CO_2, and by a strengthened bonding of NH_3 to surface acid site (Zr~(4+)) on the other hand. These results suggest that there exists not only independently located acid and base sites, responsible for the adsorption of NH_3 and CO_2, but some sites located closely (i.e acid-base pair sites). A surface induced through-bond acid-base interaction seems to be the nature of the dual adsorption effect.

Key words: Zirconium dioxide, Acid-base interaction, Surface induced interaction, TPD, IR, NH3, CO2