SURFACE-COMPOSITION OF SNO2-ZRO2 BINARY OXIDE CATALYST AND ITS SELECTIVITY FOR C3H6-NO REACTION

The relation between the composition of outermost surface layer on SnO//2-ZrO//2 binary oxide catalyst and catalytic selectivity in the C//3H//6-NO reaction has been investigated by XPS technique. The composition of outermost surface layer was estimated from a comparison of the intensity ratios of X-ray induced Auger peak or XPS peak of Sn to XPS peak of Zr. A superficial enrichment of Zr was observed in these catalysts calcined at 600 degree C in the air, while surface enrichment of Sn took place during the course of evacuation at 450 degree C. The catalytic selectivity for formation of acrylonitrile showed a maximum with the catalyst containing Sn and Zr in the same concentration at the outermost surface layer of catalyst.