In Situ XAFS Study of Dynamic Behavior of Cu Species in MFI-Zeolite under Element Gases of Ammonia Selective Catalytic Reduction

摘要

We studied the dynamic redox behavior of Cu species in zeolite matrix under NFI3-SCR using in situ XAFS. Cu~(2+) species were slowly reduced to Cu~+ in flowing NH3, and subsequent addition of NO promoted the reduction to Cu~+. In the oxidation step, oxygen alone did not fully oxidize Cu~+ to Cu~(2+), but the Cu~+ species were completely oxidized to Cu~(2+) by NO-O_2. The oxidation step was slower than the reduction step, which suggested that the oxidation step (Cu~+ → Cu~(2+)) is the slow step of the NH3-SCR reaction.