NO reduction by CO over a Fe-based catalyst in FCC regenerator conditions

• A crucial problem for NOx reduction is to overcome the negative effect of O2.
• The Fe catalyst enhances the consumption of O2 and improves NO reduction by CO.
• A kinetics model was proposed to describe the effect of O2 concentration.
• The reaction rate constant k decreased with the increase of O2 concentration.
• The negative of O2 is attributed to the stronger adsorption ability of O2 than NO.

A newly route for reduction of NOx by CO in the presence of an oxidization catalyst was proposed. In this strategy, O2 is first consumed by CO in the presence of oxidized catalyst, and then NO in the deoxidized flue gas is reduced by CO in the presence of reduced catalyst. The catalytic performance of a Fe-based catalyst as an oxidization catalyst for the reduction of NO by CO under typical FCC regeneration conditions was investigated. In comparison with the FCC catalyst, the Fe-based catalyst enhances a rapid consumption of O2 and improves the reduction of NO by CO even at lower temperatures. A kinetics model was proposed to describe the effect of O2 concentration on the reduction of NO by CO. The reaction rate constant k increased with the temperature but decreased with the increase of O2 concentration. The CO–NO reaction will not occur until the O2 concentration is below a threshold value, which would be attributed to the stronger adsorption ability of O2 than NO. This newly developed approach is efficient and might be extended to the reduction of NO derived from coal combustion plant by precisely controlling the O2 concentration.