High pressure study of H2 oxidation and its interaction with NO

Abstract

Abstract The present study deals with the oxidation of H2 at high pressure and its interaction with NO. The high pressure behavior of the H2/NOx/O2 system has been tested over a wide range of temperatures (500–1100\xa0K) and different air excess ratios (λ\xa0=\xa00.5–6.4). The experiments have been carried out in a tubular flow reactor at 10, 20 and 40\xa0bar NO has been found to promote H2 oxidation under oxidizing conditions, reacting with HO2 radicals to form the more active OH radical, which enhances the conversion of hydrogen. The onset temperature for hydrogen oxidation, when doped with NO, was approximately the same at all stoichiometries at high pressures (40\xa0bar), and shifted to higher temperatures as the pressure decreases. The experimental results have been analyzed with an updated kinetic model. The reaction N O + N O + O 2 ⇌ N O 2 + N O 2 has been found to be important at all conditions studied and its kinetic parameters have been modified, according to its activation energy uncertainty. Furthermore, the kinetic parameters of reaction H N O + H 2 ⇌ N H + H 2 O have been estimated, in order to obtain a good prediction of the oxidation behavior of H2 and NO conversion under reducing conditions. The kinetic model shows a good agreement between experimental results and model predictions over a wide range of conditions.