Catalytic reduction of NO with NH3 over carbons impregnated with Cu and Fe.

Selective catalytic reduction (SCR) with NH3 remains as one of the most effective technologies controlling NOx emission from stationary sources. At low temperatures carbon exhibits higher catalytic activity in NOx reduction than conventional catalysts made of metal oxides or zeolites. In the present work, the rate of catalytic NO reduction conducted at 110-200 degrees C over mineral matter free carbon particles was found to be low, contrary to the findings reported in the literature. The activity of the carbon was significantly enhanced from impregnating it with nitrates of Cu and Fe. The carbon impregnated with Cu shows the highest activity. The affinity of these carbon catalysts toward NH3 and NO, as well as the tendency of the impregnated metal oxides toward reduction by carbon and H2, has an order identical to that of their activity in NO reduction. The high activity of the metal-loaded carbons was related to the combined catalytic effects of the carbon and the metal. It has been suggested on the basis of this study that the metal-carbon complexes may serve as the catalytic centers for oxygen transference from NO to NH3, which is essentially slow in the absence of the metal.