Aljama Hassan A, Head-Gordon Martin, Bell Alexis T
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA.
Department of Chemistry, University of California, Berkeley, CA, USA.
Nat Commun. 2022 May 25;13(1):2910. doi: 10.1038/s41467-022-29505-z.
Cation exchanged-zeolites are functional materials with a wide range of applications from catalysis to sorbents. They present a challenge for computational studies using density functional theory due to the numerous possible active sites. From Al configuration, to placement of extra framework cation(s), to potentially different oxidation states of the cation, accounting for all these possibilities is not trivial. To make the number of calculations more tractable, most studies focus on a few active sites. We attempt to go beyond these limitations by implementing a workflow for a high throughput screening, designed to systematize the problem and exhaustively search for feasible active sites. We use Pd-exchanged CHA and BEA to illustrate the approach. After conducting thousands of explicit DFT calculations, we identify the sites most favorable for the Pd cation and discuss the results in detail. The high throughput screening identifies many energetically favorable sites that are non-trivial. Lastly, we employ these results to examine NO adsorption in Pd-exchanged CHA, which is a promising passive NO adsorbent (PNA) during the cold start of automobiles. The results shed light on critical active sites for NO capture that were not previously studied.
阳离子交换沸石是一种功能材料，具有从催化到吸附剂等广泛的应用。由于存在众多可能的活性位点，它们给使用密度泛函理论的计算研究带来了挑战。从铝的构型，到额外骨架阳离子的位置，再到阳离子可能不同的氧化态，考虑所有这些可能性并非易事。为了使计算数量更易于处理，大多数研究集中在少数活性位点上。我们试图通过实施一种高通量筛选工作流程来突破这些限制，该流程旨在将问题系统化并详尽地搜索可行的活性位点。我们使用钯交换的CHA和BEA来阐述该方法。在进行了数千次显式密度泛函理论计算后，我们确定了对钯阳离子最有利的位点，并详细讨论了结果。高通量筛选识别出了许多能量上有利但并非显而易见的位点。最后，我们利用这些结果来研究钯交换CHA中NO的吸附情况，钯交换CHA在汽车冷启动期间是一种很有前景的被动NO吸附剂（PNA）。这些结果揭示了以前未研究过的NO捕获关键活性位点。
