No Reduction by Activated Carbons. 2. Catalytic Effect of Potassium

The results of an investigation are reported concerning the NO reduction activity of different carbons loaded by ion exchange with varying amounts of a potassium catalyst. The samples were characterized by physical adsorption of CO₂ (at 0 °C) and N₂ (at -196 °C) and by chemisorption of CO₂ at 250 °C. The reactivity of the pure carbons was determined in both NO and CO₂. The catalytic effect of potassium in NO reduction was evaluated in a fixed-bed flow reactor at atmospheric pressure using two types of experiments: (i) temperature-programmed reaction in a NO/He mixture; and (ii) isothermal reaction at 300-600 °C. The reaction products were monitored in both cases, thus allowing detailed oxygen and nitrogen balances to be determined. Potassium was found to be an excellent catalyst for the NO reduction by carbon. At temperatures below 600 °C, the products of the reaction were primarily N₂ and CO₂. The catalytic activity, and thus the concentration of catalytically active sites, is dependent on both catalyst dispersion and carbon reactivity.