Selective catalytic reduction of NOx over micro-/meso-/macroporous Cu-SAPO-34

Abstract

Micro-/meso-/macroporous Cu-containing SAPO-34 was successfully prepared by the post-synthetic modification of a commercial support with diethylamine (DEA). The treatment in disodium ethylenediaminetetraacetate (Na₂H₂EDTA) did not yield a micro-/mesoporous material. The post-synthetic modification of SAPO-34 allows for the introduction of a higher content of copper species (1–2.6 wt%) compared to the unmodified material (0.5 wt%). Cu-SAPO-34_DEA exhibits the highest NO conversion below 250 °C, and the widest activity temperature window to achieve >80% of NO conversion (200–450 °C) during NH₃-SCR-DeNO_x. However, the presence of H₂O in the feed was detrimental to all the materials. As evidenced by DR UV-vis and in situ XPS, the mobility of copper species and their accumulation in the internal part of SAPO-34 grains appeared with increasing temperature. By employing the rapid scan FT-IR approach, the consecutive reaction steps were identified in the first 300 s of NH₃-SCR-DeNO_x in the presence of H₂O.