SO2-resistant NOx reduction over Cu-SAPO-34 catalysts via creating sulfur-phobic Cu sites

Abstract

Commercial Cu-SAPO-34 catalysts suffer from poisoning of SO₂ in the selective catalytic reduction of NO_x with NH₃ (NH₃-SCR). It is challenging to inhibit the deposition of ammonium hydrogen sulfate (ABS) and the sulfation of Cu species in the presence of SO₂. Here, we originally demonstrate that sulfur-philic ZCuOH sites could be converted into sulfur-phobic Z₂Cu sites in Cu-SAPO-34 by a hydrothermal aging (HA) method, thereby improving the SO₂ resistance. After the HA treatment, the SO₂ adsorption capacity and ABS deposition over catalysts are both reduced by 30–40% compared to that over the original counterpart. Moreover, SO₂-induced overoxidation and polymerization of Cu species are also suppressed, thus maintaining the redox balance of the NH₃-SCR reaction. This work provides an effective approach to enhance the SO₂ resistance of Cu-SAPO-34 catalysts via creating sulfur-phobic Z₂Cu sites, which is of significance for practical applications.