Effects of hydrogen addition on the removal of nitric oxide by cyanuric acid

Abstract

Selective, non-catalytic techniques for removing nitric oxide (NO) from exhaust gases include the addition of cyanuric acid (CA) to the hot exhaust. This work examines the effects of hydrogen (H 2 ) on the cyanuric acid-NO reduction process. Cyanuric acid was vaporized and mixed with a gas stream composed of N 2 , O 2 , H 2 and NO in an electrically heated quartz flow reactor. The NO reduction and the products of the process were examined as a function of reactor temperature with a chemiluminescent NO x analyzer and a Fourier transform infrared (FTIR) spectrometer. Addition of H 2 lowered the reactor temperature at which NO reduction occurred and increased both the quantity of NO removed and the temperature range over which NO reduction occurred. The effects of H 2 on the process result from the oxidation of H 2 and the generation of free-radicals that drive the NO reduction mechanism. Species observed in the exhaust stream of the reactor under various conditions included: H 2 O, CO 2 , CO, NO, N 2 O, HNCO, and CA. The quantity of each species depended on the reactor temperature and the input concentrations of H 2 , NO and CA.