Kinetic modeling of the reduction of nitric oxide in combustion products by isocyanic acid

Abstract

AbstractThe RAPRENOx process for NO reduction in combustion products involves reaction of nitric oxide with isocyanic acid. We have developed a mechanism for the gas‐phase reaction of isocyanic acid with nitric oxide in the presence of various amounts of O2, H2O, and CO. Kinetics calculations using the mechanism are compared with the experimental data of Siebers and Caton, and the model reproduces all trends of these data. Sensitivity and rate‐of‐production analyses show that the reactions of HNCO with OH, O, and H play a major role in the NO‐removal process and that NO removal occurs primarily by reaction of NO with NCO to form N2O, which subsequently reacts slowly to form N2. The overall reaction is critically dependent on production of radicals. When O2, H2O, and CO are present, the radicals are supplied by the moist‐CO chain branching sequence. When any of these species is absent, radicals must be supplied by other reactions, principally the N2O decomposition reaction and the reaction of the NH2 radical with NO.