Cu-EAB zeolite catalyst: A promising candidate with excellent SO2 poisoning resistance for NH3-SCR reaction

Abstract

In this work, we synthesized Cu_x-EAB catalysts with an EAB topology for the NH₃-SCR of NO_x and evaluated their resistance to SO₂ poisoning for the first time. The Cu_2.53-EAB catalyst showed superior NO_x conversion and selectivity for N₂, along with a notable tolerance to high space velocities and SO₂, outperforming the commercial Cu_2.61-CHA catalyst. This enhanced resistance was attributed to the Cu^2 + species formation at the 2.53 wt% loading, which were mainly located in the double 6-rings and 8-rings of the Cu_2.53-EAB structure. The catalyst performance was stable even after SO₂ exposure and multiple NH₃-SCR cycles. Sulfation treatments at both 200 °C and 400 °C reduced the NO_x conversion rates of the Cu_2.53-EAB and Cu_2.61-CHA catalysts. Comparative characterizations before and after sulfation revealed that the NH₃-SCR activity of Cu_2.53-EAB was less affected by the sulfation treatment at 400 °C. The coverage of active sites by H₂SO₄ and CuSO₄ was identified as the primary cause of activity reduction for both catalysts after sulfation at 200 °C and 400 °C. A hybrid Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanism for the NH₃-SCR reaction over Cu_2.53-EAB was proposed, based on in situ DRIFTS analysis. The results show that the Cu-EAB catalyst is a promising alternative for NH₃-SCR applications, offering improved SO₂ resistance and NO_x elimination capabilities.