Cu-SSZ-13 catalysts, used in NO selective catalytic reduction (SCR) with NH, experience deactivation due to hydrothermal aging. Mild hydrothermal aging, which precedes significant zeolitic framework collapse, forms occluded CuO clusters within the catalyst pores. We examined a commercial Cu-SSZ-13 catalyst’s physical and chemical properties using steady-state catalytic tests, Brunauer-Emmett-Teller analysis, reactive titrations, and temporally resolved diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements. Reductive titrations (NO + NH) and steady-state deNO (without O) proved valuable for detecting these clusters. The activation barrier for deNO decreased from 50 kJ/mol to 15 kJ/mol as CuO cluster concentration increased with aging. Additionally, DRIFTS during NO and NH adsorption on aged catalysts revealed that these clusters could dissociate NH into NH and OH, identified by new infrared bands at 3,580 and 3,640 cm, respectively. We posit that the NH species act as intermediates, reacting with NO to form N without O.

中文翻译：

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水热老化 Cu-SSZ-13 SCR 催化剂中吸留 CuxOy 纳米团簇的实验视角


用于使用 NH 进行 NO 选择性催化还原 (SCR) 的 Cu-SSZ-13 催化剂会因水热老化而失活。轻微的水热老化发生在沸石骨架显着崩溃之前，在催化剂孔内形成封闭的 CuO 簇。 我们使用稳态催化测试、Brunauer-Emmett-Teller 分析、反应滴定和时间分辨漫反射红外傅里叶变换光谱 (DRIFTS) 测量检查了商用 Cu-SSZ-13 催化剂的物理和化学性质。事实证明，还原滴定 (NO + NH) 和稳态 deNO（无 O）对于检测这些簇很有价值。随着 CuO 簇浓度随着老化而增加，deNO 的活化势垒从 50 kJ/mol 降至 15 kJ/mol。此外，老化催化剂上 NO 和 NH 吸附过程中的漂移表明，这些簇可以将 NH 解离为 NH 和 OH，分别由 3,580 cm 和 3,640 cm 处的新红外波段识别。我们假设 NH 物种充当中间体，与 NO 反应形成 N，而无需 O。