Influence of Char Surface Chemistry on the Reduction of Nitric Oxide with Chars

The reactions of brown coal chars with nitric oxide, oxygen, and their mixture were carried out at 300 °C. The copper-catalyzed char-NO reaction was remarkably enhanced by the presence of O₂. The formation of reactive surface intermediates (C(O)) and stable carbon-oxygen complexes (C-O) during these reactions was investigated by the combination of transient kinetics and temperature-programmed desorption techniques. The majority of the carbon-oxygen complexes generated during the reactions were the stable C-O species. The concentration of reactive C(O) was increased by the presence of both O₂ and Cu catalyst. To further investigate the influence of carbon surface chemistry, the reduction of NO was carried out with partially gasified char samples subjected to various surface treatments. A mechanism is proposed to account for the observed kinetic behavior.