Effect of Hydrocarbon on DeNOx Performance of Copper Zeolites: Combination of NH3/ and HC/SCR

Iljeong  Heo, Korea Research Institute of Chemical Technology

HC/SCR using fuel HC as a reductant for NOx has extensively studied as a potential deNOx system, although NOx reduction performance by HC is insufficient for real application to date. One way to improve the deNOx performance is to employ NH3/SCR catalyst which use NH3 generated during the course of HC/SCR. Thus, the effect of hydrocarbons (HCs) on NH₃/SCR over five types of Cu-exchanged zeolite catalysts has been examined. Small pore zeolites including CuSSZ-13 (3-D pore channel) and CuFER (2-D pore channel) showed excellent resistance to the poisoning by heavy HCs such as C₁₂H₂₆ and C₈H₁₀, while severely poisoned by C₃H₆. CuZSM-5 and CuBEA containing 3-D medium and large pore channels, respectively, revealed the significant HC poisoning by C₁₂H₂₆. Another large pore based catalyst with 1-D channels, CuMOR, showed peculiar behavior of HC poisoning among the catalysts examined. Decrease and increase of NOx reduction activity by HC included in the reaction feed were due to the surface NO oxidation, ammoxidation and HC/SCR over each Cu/zeolite catalyst.