STUDIES ON ACTIVE SPECIES FOR SELECTIVE CATALYTIC REDUCTION OF NO ON ALUMINA-SUPPORTED COBALT OXIDE CATALYSTS

Alumina-supported cobalt oxide catalysts were prepared by three differ ent methods: The impregnation and sol/gel methods using either an acid or a base as a precipitant. The catalysts prepared by sol/gel methods , followed by calcination at 773 K, exhibited a significant activity f or the selective catalytic reduction (SCR) of NO with propene as a red uctant. The catalyst prepared by impregnation showed poor activity whe n it was calcined at 773 K, but exhibited enhanced activity when calci ned at 1073 K. This is attributed to tiny CoAl2O4 crystallites formed during calcination of the catalyst at 1073 K. However, in sol/gel cata lysts, finely-divided CoAl2O4 crystallites were formed during calcinat ion, even at 773 K, because of the high dispersion of Co ions in the a lumina support. Thus, the active species of alumina-supported cobalt o xide catalysts for SCR of NO with propene were concluded to be tiny Co Al2O4 crystallites dispersed on alumina.