Location and nature of Cu species in Cu/SAPO-34 for selective catalytic reduction of NO with NH3

Cu/SAPO-34 catalysts have been reported to show much improved activities and durability for selective catalytic reduction (SCR) of NOx. In this work, we examined the nature of Cu species in SAPO-34 catalysts in order to shed light on the active site requirements. Cu/SAPO-34 catalysts, prepared by ion-exchange and precipitation methods, were characterized in detail. The results consistently indicate that Cu species exist predominantly as isolated ions at the exchange sites in the ion-exchanged sample, whereas in the precipitated sample CuO on the external surface is the dominant species. The ion-exchanged Cu/SAPO-34 was found to show superior NH3-SCR activity than the precipitated sample, suggesting that isolated Cu ions at the exchange sites are likely the active sites.

Cu/SAPO-34 with isolated Cu ions at the exchange sites is considerably more active for NH3 SCR than Cu/SAPO-34 with external CuOx species at the same Cu loading.Figure optionsDownload high-quality image (36 K)Download as PowerPoint slideHighlights
► We prepare two Cu/SAPO-34 samples with two different Cu species.
► Catalysts for selective catalytic reduction of NOx with ammonia.
► We examine the location and nature of the Cu species in the samples.
► The sample with exchanged Cu ions shows much higher reaction rates.