Micro-/mesoporous copper-containing zeolite Y applied in NH3-SCR, DeNOx

Zeolite Y was prepared by a dense-gel method and subsequently modified either by treatment with diethylamine (DEA), sodium hydroxide (NaOH) or disodium ethylenediaminetetraacetate (Na2H2EDTA), or by sequential treatment (H4EDTA-NaOH or H4EDTA-NaOH-Na2H2EDTA). Individual treatment did not succeed in introducing mesoporosity in the parent zeolite Y, while the sequential treatment lead to formation of mesopores. After introduction of Cu2+ ions, the obtained materials were studied as catalysts for the selective catalytic reduction of NOx by NH3 (NH3-SCR, DeNOx). The catalytic investigations reveal a similar NO conversion for all Cu-containing catalysts up to 450 °C, independent of the introduced mesoporosity. Insights into the dynamics of NH3-SCR intermediates through rapid scan FT-IR show that for Cu–Y, the rate-determining step is the formation of the mixed [Cu(O−)(NH3)n-1(NO)]2+ complexes, which initiate the NH3-SCR reaction.