New spinel materials for catalytic NO-CO reaction: nonstoichiometric nickel-copper manganites

Nonstoichiometric nickel-copper spinel manganites were found to be highly a ctive for the reduction of nitric oxide by carbon monoxide at low temperatu re (300 degreesC). The activity increases with the level of nonstoichiometr y of the oxides and almost linearly with their specific surface area. Moreo ver, this activity was found to depend strongly on the copper content, nick el manganites being almost inactive. The influence of the surface state of the oxides was also investigated. Cuprous cations are thought to play the d etermining role in the catalytic cycle. (C) 2001 Elsevier Science B.V. All rights reserved.