A theoretical study of the formation of a nitrogen-nitrogen triple bond from RNH2 and NO species: Implications for the selective catalytic reduction of nitrogen oxides

In the light of possible similarities between the selective catalytic reduction of oxides of nitrogen by ammonia in the presence of molecular oxygen, and the diazotisation of primary amines by nitrous acid, we have carried out electronic structure calculations (UB3LYP/6-311++G(2d,2p)//UB3LYP/6-31G**) of the possible steps involved in the step-wise formation of an N N triple bond from NH3 and HONO, via N2O3. We have found that proton shuttle mechanisms, facilitated by water and nitrous acid provide a low energy pathway, consistent with the rate determining step being the formation of N2O3. We have shown that similar proton shuttle steps may occur at an acidic zeolite site. © 2003 Elsevier Science B.V. All rights reserved.