As a prominent contributor to air pollution, nitric oxide (NO) has emerged as a critical agent causing detrimental environmental and health ramifications. To mitigate emissions and facilitate downstream utilization, adsorption-based techniques offer a compelling approach for direct NO capture from both stationary and mobile sources. In this study, a comprehensive exploration of NO capture under oxygen-lean and oxygen-rich conditions was conducted, employing Ni ion-exchanged chabazite (CHA-type) zeolites as the adsorbents. Remarkably, Ni/Na-CHA zeolites, with Ni loadings ranging from 3 to 4 wt%, demonstrate remarkable dynamic uptake capacities and exhibit exceptional NO capture efficiencies (NO-to-Ni ratio) for both oxygen-lean (0.17–0.31 mmol/g, 0.32–0.43 of NO/Ni) and oxygen-rich (1.64–1.18 mmol/g) under ambient conditions. An NH3 reduction methodology was designed for the regeneration of absorbents at a relatively low temperature of 673 K. Comprehensive insights into the NOx adsorption mechanism were obtained through temperature-programmed desorption experiments, in situ Fourier transform infrared spectroscopy, and density functional theory calculations. It is unveiled that NO and NO2 exhibit propensity to coordinate with Ni2+via N-terminal or O-terminal, yielding thermally stable complexes and metastable species, respectively, while the low-temperature desorption substances are generated in close proximity to Na+. This study not only offers micro-level perspectives but imparts crucial insights for the advancement of capture and reduction technologies utilizing precious-metal-free materials.

中文翻译：

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对载镍 CHA 分子筛进行高效的一氧化氮捕获和还原


作为空气污染的主要贡献者，一氧化氮 （NO） 已成为一种关键因素，对环境和健康造成不利影响。为了减少排放并促进下游利用，基于吸附的技术提供了一种从固定和移动源直接捕获 NO 的引人注目的方法。在本研究中，以 Ni 离子交换菱沸石 （CHA 型） 分子筛为吸附剂，对贫氧和富氧条件下的 NO 捕获进行了全面探索。值得注意的是，Ni 负载量为 3% 至 4 wt% 的 Ni/Na-CHA 沸石在环境条件下表现出卓越的动态吸收能力，并且在贫氧（0.17-0.31 mmol/g、0.32-0.43 的 NO/Ni）和富氧（1.64-1.18 mmol/g）下表现出优异的 NO 捕获效率（NO 与 Ni 比率）。设计了一种 NH3 还原方法，用于在 673 K 的相对低温下吸收剂的再生。通过程序升温脱附实验、原位傅里叶变换红外光谱和密度泛函理论计算，全面了解了 NOx 吸附机理。结果表明，NO 和 NO2 表现出通过 N 端或 O 端与 Ni2+ 配位的倾向，分别产生热稳定的络合物和亚稳态物质，而低温解吸物质是在靠近 Na+ 的地方产生的。这项研究不仅提供了微观层面的视角，而且为利用无贵金属材料的捕获和还原技术的发展提供了重要的见解。