Studies on active species for selective catalytic reduction of NO on alumina-supported cobalt oxide catalysts

Article abstract of DOI:10.1246/bcsj.71.2331

Alumina-supported cobalt oxide catalysts were prepared by three different 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 for the selective catalytic reduction (SCR) of NO with propene as a reductant. The catalyst prepared by impregnation showed poor activity when it was calcined at 773 K, but exhibited enhanced activity when calcined at 1073 K. This is attributed to tiny CoAl₂O₄ crystallites formed during calcination of the catalyst at 1073 K. However, in sol/gel catalysts, finely-divided CoAl2O₄ crystallites were formed during calcination, even at 773 K, because of the high dispersion of Co ions in the alumina support. Thus, the active species of alumina-supported cobalt oxide catalysts for SCR of NO with propene were concluded to be tiny CoAl₂O₄ crystallites dispersed on alumina.