Selective reduction of nitrogen oxides (NOx) by ammonia over honeycomb selective catalytic reduction catalysts

Abstract

Data are presented for the effects of feed composition (O[sub 2], NO [sub x], NH[sub 3], H[sub 2]0, SO[sub 2] concentrations) and of the operating conditions (area velocity, reaction temperature, and Re number) on the NO[sub x] removal efficiency over commercial-type honeycomb DeNOxing catalysts with different compositions and geometric characteristics. All of these data are explained by a Rideal type kinetic expression, derived assuming reaction between strongly adsorbed ammonia and gaseous or weakly bonded NO. The significance of interphase and intraparticle diffusion limitations is discussed, and a comprehensive model of the SCR monolith reactor is illustrated which fully accounts for both external and internal transport of the reactants as well as for the effects of the operating variables and of the feed composition under representative SCR conditions.