Copper exchanged chabazites are among the state-of-the-art catalyst materials being studied for selective catalytic reduction of NOx, however, there is still a need to understand how these materials store ammonia after aging. In this work, studies are performed to assess the ammonia storage capacity of Cu-SSZ-13 as a function of concentration, temperature, and extent of hydrothermal aging. Ammonia binds at three difference sites: (i) a Cu site bound at 1 framework Al (Z₁Cu site), (ii) a Cu site bound at 2 framework Al (Z₂Cu site), and (iii) a Brønsted acid site (ZH site). Results show that a 3-site model can accurately capture ammonia storage across all conditions. Impacts for hydrothermal aging are considered via 3 aging reactions that change the site densities of each identified adsorption site. Model assessment shows that during aging there is a significant loss in Brønsted acid sites.

铜交换菱沸石是正在研究用于选择性催化还原 NOx 的最先进的催化剂材料之一，但是，仍然需要了解这些材料在老化后如何储存氨。在这项工作中，进行了研究以评估 Cu-SSZ-13 的氨储存能力作为浓度、温度和水热老化程度的函数。氨在三个不同的位点结合：(i) Cu 位点结合在 1 骨架 Al (Z ₁ Cu 位点)，(ii) Cu 位点结合在 2 骨架 Al (Z ₂Cu 位点），和（iii）布朗斯台德酸位点（ZH 位点）。结果表明，3 位点模型可以准确捕获所有条件下的氨储存。水热老化的影响通过 3 个老化反应来考虑，这些反应改变了每个已识别吸附位点的位点密度。模型评估表明，在老化过程中，Brønsted 酸性位点有显着损失。