Charge Shielding Effect of Sodium Ions in Improving The Hydrophobicity and Performance of Co/Na-SSZ-13 Zeolite for Passive NOx Adsorber
Charge Shielding Effect of Sodium Ions in Improving The Hydrophobicity and Performance of Co/Na-SSZ-13 Zeolite for Passive NOx Adsorber
复制标题
DOI：
10.1002/adfm.202310682
复制
发表时间：
2024-01-11
影响因子：
19
通讯作者：
Guo，Yanbing
中科院分区：
文献类型：
--
作者：
Chen，Zhen;Tao，Qian;Guo，Yanbing
随着法规的日益严格，降低汽车冷启动过程中的NOx排放是一个重大挑战。Pd改性沸石被认为是最有希望用于冷启动NOx控制的被动式NOx吸附器。然而，钯的稀缺性和高昂的成本限制了其实际应用。本文报道了一种用于低温吸附NOx的非贵金属改性的Co/Na-SSZ-13分子筛。这种一锅法合成的Co/Na-SSZ-13分子筛在潮湿条件下(3%H2O v/v)表现出超高的NOx存储容量(212g/mmolSSZ-−1)，是常规Co或Pd改性的SSZ-13的两倍多。这归因于传统Co-SSZ-13中没有常见的惰性层状硅酸钴，以及Co/Na-SSZ-13中高度分散的Co和Na离子作为有效的NOx吸附中心。此外，Na离子的存在屏蔽了Al中心产生的负电荷，并削弱了Al和Co中心的局部电场强度。这降低了分子筛对H2O的吸附能，改善了分子筛的疏水性，从而提高了Co/Na-SSZ-13在潮湿条件下的NO储存能力。本工作重点介绍了Co/Na-SSZ-13，通过一种简单高效的方法合成，作为贵金属PNA材料的有前途的替代品。
With increasingly stringent regulations, the reduction of NOxemissions during vehicle cold start is a major challenge. Pd‐modified zeolites are considered as the most promising passive NOxadsorber (PNA) for cold start NOxcontrol. Nevertheless, the scarcity and the high cost of Pd limit its practical application. Herein, a non‐precious metal modified Co/Na‐SSZ‐13 zeolite for low‐temperature NOxadsorption is reported. This one‐pot synthesized Co/Na‐SSZ‐13 exhibits an extraordinary NOxstorage capacity (212 µmol gcat−1) under humid conditions (3% H2O v/v), which is more than double that of conventional Co or Pd‐modified SSZ‐13. This is attributed to the absence of the inert cobalt phyllosilicate commonly found in conventional Co‐SSZ‐13, as well as the highly dispersed Co and Na ions as the effective NOxadsorption sites in Co/Na‐SSZ‐13. Moreover, the presence of Na ions shields the negative charge generated by the Al center and weakens the local electric field strength of the Al and Co centers. This lowers the H2O adsorption energy and improves the zeolite hydrophobicity, which enhances the NO storage capacity of the Co/Na‐SSZ‐13 under humid conditions. This work highlights the Co/Na‐SSZ‐13, synthesize via a simple and high‐efficiency method, as a promising substitute for noble metal PNA materials.