Kinetics of nitric oxide desorption from carbonaceous surfaces

We carried out a molecular modeling study of an important reaction in the combustion of nitrogen-containing chars, the evolution of nitric oxide, (CNO)→NO+(C*). Density functional theory at the B3LYP level was used to provide potential energy surface information and transition state theory was used to provide temperature dependant rate constants. Desorption of NO from nitrogen-containing carbonaceous surfaces is modeled from a pyridine-N-oxide model. The fitted Arrhenius expression for the NO desorption process is k(T)=8.84×1013 exp[−42 132 K/T] (s−1). We found that the rate constants to release CO are slightly larger than rate constants to release NO from the carbonaceous surface. The NO desorption activation energy is 10 kcal/mol lower than that of the CO desorption.