Studies on the Reduction of Nitric Oxide by Carbon: The NO-Carbon Gasification Reaction

The heterogeneous reduction of NO by carbon was studied in a thermogravimetric analysis system, employing both pseudosteady and transient reaction methods. The reaction was studied at temperatures from near ambient up to 1073 K, and at NO partial pressures in the range 1.01-10.1 kPa. A relatively pure carbon derived from phenolic resin was studied. Gaseous products of rection were measured. The gasification of carbon by NO involves two parallel processes: (1) somewhat slow desorption of relatively stable surface complexes; (2) processes involving NO attack on active unoccupied sites that results in essentially immediate desorption of gaseous products. The first process controls the overall gasification rate at lower temperatures and is governed by a distribution of desorption activation energies, involving mainly surface oxides that yield CO upon desorption. The second process dominates at high temperatures (somewhat arbitrarily defined by T > 650 °C or 923 K) and is suggested to be controlled by the dissociative chemisorption of NO on the carbon surface.