Pd-promoted WO3-ZrO2 for low temperature NOx storage
Pd-promoted WO3-ZrO2 for low temperature NOx storage
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DOI：
10.1016/j.apcatb.2019.118499
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发表时间：
2020-05
影响因子：
22.1
通讯作者：
Yaying Ji;Shuli Bai;Dongyan Xu;D. Qian;Zili Wu;Yang Song;Robby Pace;M. Crocker;K. Wilson;A. Lee;Deb Harris;D. Scapens
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文献类型：
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作者：
Yaying Ji;Shuli Bai;Dongyan Xu;D. Qian;Zili Wu;Yang Song;Robby Pace;M. Crocker;K. Wilson;A. Lee;Deb Harris;D. Scapens
研究了Pd改性ZrO 2和WO 3-ZrO 2（W-Zr）对NOx的低温吸附和释放性能。Pd促进的W-Zr在短的储存时间内表现出高的NOx储存效率，随后在热升温至350 °C时释放约95%的储存的NOx。DRIFTS研究表明，Pd增加硝酸盐的形成相对于亚硝酸盐的NOx存储过程中的Pd-Zr和Pd-W-Zr。此外，Pd-W-Zr上的Pd位点在NOx储存中起主要作用，ad-物种在350 °C下容易地被去除。从NO-和CO-DRIFTS数据，据推断，Pd的酸性W-Zr载体上存在的主要是阳离子物种，因此能够吸附NO，而在ZrO 2 Pd不能直接存储NOx。CO与NO的共进料导致Pd-W-Zr的NOx储存容量增加，DRIFTS测量的基础上，这归因于Pd 2+（CO）（NO）络合物的形成。
Pd-promoted ZrO2and WO3-ZrO2(W-Zr) were investigated for low temperature NOx adsorption and release. Pd-promoted W-Zr exhibited high NOx storage efficiency at short storage times, subsequently releasing ∼95% of the stored NOx upon thermal ramping to 350 °C. DRIFTS studies demonstrated that Pd increased nitrate formation relative to nitrite during NOx storage on both Pd-Zr and Pd-W-Zr. Moreover, Pd sites on Pd-W-Zr played a major role in NOx storage, the ad-species being readily removed by 350 °C. From NO- and CO-DRIFTS data, it is inferred that Pd on the acidic W-Zr support was present as mainly cationic species, and was therefore able to adsorb NO, whereas on ZrO2Pd was not able to directly store NOx. Co-feeding CO with NO resulted in increased NOx storage capacity for Pd-W-Zr, which on the basis of DRIFTS measurements is attributed to the formation of Pd2+(CO)(NO) complexes.