Pd-based zeolites are attractive candidates for passive NOx adsorbers to reduce NOx emission from vehicle exhausts at low temperature. However, it is not well understood the NO adsorption/desorption mechanism in the presence of HO and CO, which are constant components in diesel exhaust. In this study, an initial Pd/SSZ-13 sample was treated by reduction in H and then oxidation in NO to obtain a hydrophilic Pd/SSZ-13 with mostly Z[Pd(OH)] sites, or by thermal aging at 750 °C to prepare a hydrophobic Pd/SSZ-13 dominated by ZPd and Z[Pd(OH)] sites. The two distinct Pd/SSZ-13 catalysts were characterized by XRD, H-TPR, Al MAS NMR, and in situ DRIFTS spectra of CO adsorption, etc. Furthermore, the NOx adsorption/desorption reaction experiments and in situ DRIFTS studies were carried out on the two Pd/SSZ-13 catalysts under various conditions to explore the role of ZPd and Z[Pd(OH)] sites in NO adsorption in the presence of HO or co-existence of HO and CO. Additionally, the recovery of active Pd sites after NO desorption was studied.

中文翻译：

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揭示 Pd/SSZ-13 上不同活性位点在低温 NOx 吸附中的作用

钯基沸石是被动氮氧化物吸附剂的有吸引力的候选者，可减少低温车辆尾气中的氮氧化物排放。然而，人们对柴油机尾气中常量成分 H2O 和 CO 存在下的 NO 吸附/解吸机制尚不清楚。在本研究中，初始 Pd/SSZ-13 样品通过 H 还原，然后在 NO 中氧化，以获得主要含有 Z[Pd(OH)] 位点的亲水性 Pd/SSZ-13，或者通过在 750 ° 下热老化C制备以ZPd和Z[Pd(OH)]位点为主的疏水性Pd/SSZ-13。通过XRD、H-TPR、Al MAS NMR、CO吸附原位DRIFTS谱等对两种不同的Pd/SSZ-13催化剂进行了表征。此外，还进行了NOx吸附/解吸反应实验和原位DRIFTS研究。在不同条件下对两种 Pd/SSZ-13 催化剂进行了表征，探讨了 H2O 存在或 H2O 和 CO 共存时 ZPd 和 Z[Pd(OH)] 位点在 NO 吸附中的作用。研究了NO解吸后的Pd位点。