A NO_x reduction by multiple injection of hydrogen peroxide

The improvement of the conventional Non-Catalytic Reduction of NO with the addition of H₂O₂ was investigated. At 800-1000 K, the pyrolysis of H₂O₂ producing OH was the only source of reactive radicals. While OH reacted with NH₃ to produce NH₂ reducing NO, reaction with remaining H₂O₂ produced HO₂, which then oxidized NO to NO₂. NO₂ could not be further reduced in this composition and temperature region. To avoid the unfavorable secondary reaction, H₂O₂ concentration must be sufficiently low compared to that of NH₃, since the rate constants of OH-NH₃ and OH-H₂O₂ were comparable. The total amount of this additives must be equivalent or in a little excess of the initial concentration of NO to be reduced, for both NH₃ and H₂O₂. In the simulation of atmospheric methane-air combustion containing 100-1000 ppm of NO, 90% reduction of NO was achieved at 800-1200 K by ten-fold injection of H₂O₂ within the 1 sec of total reaction time, where the byproduction of NO₂ was kept low throughout the conditions. Original is an abstract.