Catalytic Activities of an Active Carbon and a PAN-ACE for the Reduction of Nitrogen Monoxide with Ammonia

Abstract

Catalytic reduction of nitrogen monoxide with ammonia over a PAN-ACF, an active carbon and their derivaties further activated with sulfuric acid was studied at 150°C using a fixed catalyst-bed in a flow reactor. It was found that the catalytic conversion was influenced by nitrogen monoxide and oxygen concentrations in the reactant gas. The catalytic activities of these carbons were very much enhanced by the activation with sulfuric acid, PAN-ACF exhibiting the highest activity to convert ca.60% of nitrogen monoxide at W/F of O.02 (g.min/ml) for 20 h when the reactant gas contained 1% nitrogen monoxide without oxygen. Although the low concentration of nitrogen monoxide (400 ppm) decreased very much the stationary conversion over all carbons at the same W/F, addition of oxygen into the reactant gas (4%) increased very much the conversion and maintained the conversion level for longer than 20 h. Thus, PAN-ACF-B activated with sulfuric acid exhibited a conversion of ca.73% at W/F of 0.005 (g.min/ml). The kinetics, the reactivities of carbons against NO and TPDE of carbons (to produce CO and CO₂) suggest, that the active sites for this reaction are a portion of surface oxygen functionalities and that they are produced and regenerated during the catalytic reaction through the oxidation with NO or oxygen of relatively high concentrations (a few %) in the reactant gas.