CALCINATION CONDITIONS ON COPPER ALUMINA CATALYSTS FOR CARBON-MONOXIDE OXIDATION AND NITRIC-OXIDE REDUCTION

A commercial copper oxide/alumina catalyst with 6.5wt.-% copper metal was used to study the effect of calcination conditions on carbon monoxide oxidation and nitric oxide reduction with ammonia. Calcination in a reducing atmosphere, at temperatures up to 900-degrees-C, may induce a strong metal-support interaction which leads to enhanced activities not only for carbon monoxide oxidation but also for nitric oxide reduction. This strong metal-support interaction effect was stronger for higher calcination temperatures. It was found that high temperature treatment in a reducing atmosphere was beneficial to carbon monoxide oxidation while an oxidizing atmosphere was usually preferred for nitric oxide reduction. In addition, copper species at higher oxidation states may lead to a higher activity of nitric oxide reduction, but an optimum state may exist. It can be concluded that nitric oxide reduction is a structure-sensitive reaction over copper catalysts.