Elucidating the Effect of Ion Exchange Protocol on the Copper Exchange Efficacy, Copper Siting, and SCR activity in Cu‐SSZ‐13
Elucidating the Effect of Ion Exchange Protocol on the Copper Exchange Efficacy, Copper Siting, and SCR activity in Cu‐SSZ‐13
复制标题
阐明离子交换方案对 Cu 中铜交换效率、铜选址和 SCR 活性的影响 – SSZ – 13
DOI：
10.1002/cphc.202300271
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发表时间：
2023
期刊：
影响因子：
2.9
通讯作者：
Shantz, Daniel F.
中科院分区：
文献类型：
--
作者：
Koishybay, Aibolat;Umhey, Charles;Kuo, Chun‐Te;Groden, Kyle;McEwen, Jean‐Sabin;Karim, Ayman M.;Shantz, Daniel F.
定量研究了铜离子交换方案对SSZ - 13 SCR活性的影响。使用相同的母分子筛SSZ‐13，使用四种交换协议来评估交换协议如何影响金属吸收和SCR活性。在不同的交换协议下，SCR活性差异很大，在160°C恒定铜含量下，SCR活性差异近30个百分点，这意味着不同的交换协议导致不同的铜种类。选定样品的氢温度程序还原和CO结合的红外光谱证实了这一结论，因为160°C时的反应活性与2162 cm−1的IR波段强度相关。基于DFT的计算表明，这种红外分配与CO吸附在八元环内的Cu(I)阳离子上是一致的。这项工作表明，即使不同的方案导致相同的金属负载，SCR活性也会受到离子交换过程的影响。也许最有趣的是，在单位质量或单位摩尔铜的基础上，用于甲烷制甲醇研究的Cu - MOR生成方案导致了最活跃的催化剂。这指出了一种尚未被认可的调整催化剂活性的方法，因为公开文献对这个问题保持沉默。
The influence of the copper ion exchange protocol on SCR activity of SSZ‐13 is quantified. Using the same parent SSZ‐13 zeolite, four exchange protocols are used to assess how exchange protocol impacts metal uptake and SCR activity. Large differences in the SCR activity, nearly 30 percentage points at 160 °C at constant copper content, are observed for different exchange protocols implying that different exchange protocols lead to different copper species. Hydrogen temperature programmed reduction on selected samples and infrared spectroscopy of CO binding corroborates this conclusion as the reactivity at 160 °C correlates with the intensity of the IR band at 2162 cm−1. DFT‐based calculations show that such an IR assignment is consistent with CO adsorbed on a Cu(I) cation within an eight‐membered ring. This work shows that SCR activity can be influenced by the ion exchange process even when different protocols lead to the same metal loading. Perhaps most interesting, a protocol used to generate Cu‐MOR for methane to methanol studies led to the most active catalyst both on a unit mass or unit mole copper basis. This points to a yet not recognized means to tailor catalyst activity as the open literature is silent on this issue.