The optimal volume of a combined system of LNT and SCR catalysts

This paper aims to find the optimal volumes of the LNT (Lean NOx Trap) and SCR (Selective Catalytic Reduction) catalysts for higher de-NOx performance and suppression of N2O and NH3 in a combined system of LNT + SCR. The basic characteristics of the LNT catalyst were identified first at various space velocities (SV), and then the effects of the variation in volume of the combined system were investigated. The NOx conversion, NH3 production, and N2O emissions were evaluated of four differently sized LNT–SCR systems. Considering all together the NOx conversion, cost of the precious metal, NH3 slippage, and N2O generation, the optimal volume ratio of LNT and SCR catalysts was found to be 1:1 for the LNT–SCR system.