Catalytic reduction of nitric oxide over activated carbons

The reduction of NO to N 2 using NH 3 as a reductant over activated carbons was investigated using an integral reactor system. The effects of varying the gas-phase and surface oxygen concentrations were studied in detail. Surface oxygen was introduced by treating a coconut shell activated carbon with sulphuric acid at 100–300 °C. The type and concentration of surface oxides were investigated by infrared spectroscopy, linear temperature-programmed desorption of surface oxides, and adsorption of reactant gases. Increasing the gas-phase oxygen concentration increased NO conversion significantly. The activity of activated carbon at reaction temperatures > 150 °C was enhanced by sulphuric acid treatment. Sulphuric acid acted as an oxidizing agent and created acidic surface functionalities including carboxyl and carbonyl groups.