Fresh and SO₂-poisoned Cu-SSZ-13 selective catalytic reduction (SCR) catalysts were studied using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) in the presence of NH₃, O₂, and NO, as well as by in situ X-ray absorption spectroscopy (XAS) using H₂, He, and CO. In contrast to the fresh catalyst, inhibited reduction of Cu-species and the absence of Cu-metal nanoparticles was found in the SO₂-poisoned catalyst during heating/cooling in H₂ and CO. High structural disorder and differences in the formation of Cu-carbonyl species were seen for the SO₂-poisoned catalyst compared to the fresh catalyst. Suppressed oxidation-reduction and low mobility of Cu-species during exposure to NH₃-SCR-related gases were observed in the SO₂-poisoned catalyst, unlike in the fresh catalyst. These observations help explain catalyst deactivation during the standard NH₃-SCR reaction. The formation of Cu-metal nanoparticles in the fresh catalyst revealed another possible deactivation pathway for the SCR-catalyst in combined LNT-SCR systems during fuel-rich periods.

在NH ₃，O ₂和NO存在的情况下，使用近环境压力X射线光电子能谱（NAP-XPS）研究了新鲜的和SO ₂中毒的Cu-SSZ-13选择性催化还原（SCR）催化剂。如使用H ₂，He和CO的原位X射线吸收光谱法（XAS）相比。与新鲜催化剂相反，在SO ₂中毒后发现抑制了铜物种的还原，并且不存在铜金属纳米颗粒H ₂和CO中加热/冷却过程中的催化剂。对于SO ₂，观察到高结构无序性和Cu-羰基物质形成的差异与新鲜催化剂相比中毒的催化剂。与新鲜催化剂不同，在SO ₂中毒的催化剂中观察到了Cu物种在暴露于NH ₃ -SCR相关气体期间抑制了氧化还原和低迁移率。这些观察结果有助于解释标准NH ₃ -SCR反应过程中催化剂的失活。新鲜催化剂中Cu-金属纳米颗粒的形成揭示了在富油期间组合LNT-SCR系统中SCR催化剂的另一种可能的失活途径。