CHARACTERIZATION AND CATALYTIC BEHAVIOR OF LA2-X(SR,TH)(X)CUO4+ -LAMBDA IN REACTION NO+CO/

Two mixed oxide systems La2-xSrxCuO4+/-lambda(0.0 less than or equal t o x less than or equal to 1.0) and La2+xThxCuO4+/-lambda(0.0 less than or equal to x less than or equal to 0.4) with K2NiF4 structure were p repared by varying re values; Their crystal structures were studied by means of XRD and IR spectra. The average valence of Cu ion at B site, nonstoichiometric oxygen (A) and the chemical composition in the bulk and on the surface of the catalysts were measured by means of chemica l analysis and XPS. The catalytic behavior in reaction CO + NO was inv estigated under the regular change of average valence oi Cu ion at B s ite and nonstoichiometric oxygen (lambda). Meanwhile, the adsorption a nd activation of the small molecules NO and the mixture of NO + CO ove r the mixed oxide catalysts were studied by means of MS-TPD. The catal ytic mechanism of reaction NO + CO over these oxide catalysts were pro posed; and it has been found that, at lower temperatures the activatio n of NO is the rate determining step and the catalytic activity is rel ated to the lower valent metallic ion and its concentration, while at higher temperatures the adsorption of NO is the rate determining step and the catalytic activity is related to the oxygen vacancy and its co ncentration.