One‐pot facile synthesis of Cu‐SAPO‐34 via addition of tetraethylenepentamine and its enhanced catalytic activity in selective catalytic reduction of NO_x with NH₃

Abstract

BACKGROUND A series of Cu‐SAPO‐34 samples were prepared with different copper sources and addition of tetraethylenepentamine (TEPA) by a one‐pot method, which were applied for selective catalytic reduction of NOx with ammonia (NH3‐SCR). RESULTS Various measurements were carried out to investigate the effect of TEPA addition and copper sources used on sample properties. The results indicated that Cu‐SAPO‐34 obtained with the addition of TEPA using copper citrate (Cu‐SAPO‐34‐TC) displayed over 90% NOx conversion at 150–500 °C and excellent H2O and SO2 resistance in NH3‐SCR. This is because the addition of TEPA can control the formation of isolated Cu2+ species located at the junction of D6R in CHA cage, Site (I), which is regarded as a more easily approachable site to adsorbates (NH3 and NO) than others, thus leading to the excellent NH3‐SCR performance. Further study demonstrated that the Cu‐SAPO‐34‐TC catalyst shows much wider temperature window and more hydrothermal stability due to a greater amount of surface isolated Cu2+, fewer Si islands and more Al(IV) species. CONCLUSIONS The excellent activity of the Cu‐SAPO‐34‐TC catalyst can be attributed to the addition of TEPA, which is beneficial for controlling the isolated Cu2+ at Site (I) as well as inhibiting the aggregation of CuO species. Various characterizations also confirm that more surface Cu2+ can be produced using copper citrate as copper source. © 2022 Society of Chemical Industry (SCI).