No reduction by activated carbons. some mechanistic aspects of uncatalyzed and catalyzed reaction

This chapter discusses the mechanism of the NO–carbon reaction, both in the presence and absence of catalysts. If the catalyst is effective in reducing the activation energy of adsorption of NO, the chemisorption process occurs at low temperatures and is not accompanied by the formation of surface oxides. Both N₂ and N₂O can be produced at low temperatures. Severe catalyst deactivation is observed, however, under these conditions, which are characterized by oxygen accumulation on the surface. The transfer of oxygen from the oxidized catalytic site to the carbon is crucial for maintaining high steady-state catalytic activity. Upon restoration of the reduced catalytic site, the remaining kinetically significant reactions are characterized by the oxygen–carbon reaction. The mechanism is analogous to one of the mechanisms postulated for the selective catalytic reduction by hydrocarbons and to that of alkali- and alkaline-earth-catalyzed gasification of carbon.