Acta Phys. -Chim. Sin. ›› 1999, Vol. 15 ›› Issue (06): 568 -572 .doi: 10.3866/PKU.WHXB19990617

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Natures of Oxygen Species on the Surfaces of Ce-Mo Oxides and Catalytic Activities for the Selective Oxidation of Toluene

Shangguan Rong-Chang, Ge Xin, Zhang Hui-Liang   

  1. Department of Chemistry,Nanjing University,Nanjing 210093
  • Received:1998-07-08 Revised:1998-11-30 Published:1999-06-15
  • Contact: Ge Xin

Abstract:

A series of Ce-Mo oxide catalysts with different Ce/Mo atomic ratio were prepared and applied to selective oxidation of toluene to benzaldehyde. The structures and properties of the surfaces of catalysts were characterized by XRD, TPR and DR-UVS. The natures of oxygen species on the surfaces of these samples were studied by using temperature programmed desorption-mass spectrography(TPD-MS). The results showed that the oxygen species of multiple adsorption existed on the sample surface. And in the range of desorption temperature<900℃, for the Ce-Mo samples, not only the desorption peaks of O- species on surfaces of samples be discoved, but also the O2- species appeared. As the content of Ce in Ce-Mo oxides was changed, the activation energy of oxygen desorption(Ed) also changed. The Ed value of sample 3 (Ce/Mo=1/1) is the lowest and its selectivity of benzaldehyde in toluene oxidation is the highest. Thus, a Parallel relation between the Ed value and the selectivity for benzaldehyde existed in these Ce-Mo oxides. 

Key words: Ce-Mo oxide, TPD-MS, Natures of oxygen species on the surface, Selective oxidation of toluene