Efficient NOx abatement by passive adsorption over a Pd-SAPO-34 catalyst prepared by solid-state ion exchange
Efficient NOx abatement by passive adsorption over a Pd-SAPO-34 catalyst prepared by solid-state ion exchange
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DOI：
10.1016/j.cclet.2023.108870
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发表时间：
2023-08
影响因子：
9.1
通讯作者：
Linhui Liu;Wuwan Xiong;Mingli Fu;Junliang Wu;Zhenguo Li;D. Ye;Peirong Chen
中科院分区：
文献类型：
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作者：
Linhui Liu;Wuwan Xiong;Mingli Fu;Junliang Wu;Zhenguo Li;D. Ye;Peirong Chen
钯交换菱沸石（Pd-CHA）作为被动NOx吸附剂（PNAs）能够有效净化冷启动柴油机排气中的氮氧化物（NOx）。然而，由于缺乏简便的制备方法，它们的商业应用受到限制。本文采用改进的固态离子交换法（SSIE），以PdO为Pd前体，合成了高性能的CHA型Pd-SAPO-34分子筛，并与传统湿化学方法制备的Pd-SAPO-34分子筛相比，显示出上级PNA性能。使用拉曼光谱和X-射线衍射的结构表征表明，SSIE方法避免了水诱导的破坏沸石骨架在Pd负载。通过原位红外光谱和X射线光电子能谱对SSIE过程的机理研究表明，PdO前体主要通过消耗沸石的-OH基团而转化为与沸石骨架配位的Pd 2+阳离子，但部分PdO也可以通过热分解在孔道中形成高度分散的Pd 0团簇.这种简化和可扩展的SSIE方法为成本有效地合成无缺陷的高性能Pd-SAPO-34沸石作为PNA催化剂铺平了新的道路。
Palladium-exchanged chabazite (Pd-CHA) zeolites as passive NOxadsorbers (PNAs) enable efficient purification of nitrogen oxides (NOx) in cold-start diesel exhausts. Their commercial application, however, is limited by the lack of facile preparation method. Here, high-performance CHA-type Pd-SAPO-34 zeolite was synthesized by a modified solid-state ion exchange (SSIE) method using PdO as Pd precursor, and demonstrated superior PNA performance as compared to Pd-SAPO-34 prepared by conventional wet-chemistry strategies. Structural characterization using Raman spectroscopy and X-ray diffraction revealed that the SSIE method avoided water-induced damage to the zeolite framework during Pd loading. Mechanistic investigations on the SSIE process byin situinfrared spectroscopy and X-ray photoelectron spectroscopy disclosed that, while PdO precursor was mainly converted to Pd2+cations coordinated to the zeolite framework by consuming the -OH groups of the zeolite, a portion of PdO could also undergo thermal decomposition to form highly dispersed Pd0clusters in the pore channels. This simplified and scalable SSIE method paves a new way for the cost-effective synthesis of defect-free high-performance Pd-SAPO-34 zeolites as PNA catalysts.