Pd-promoted WO3-ZrO2 for low temperature NOx storage

Yaying Ji; Shuli Bai; Dongyan Xu; Dali Qian; Zili Wu; Yang Song; Robert Pace; Mark Crocker; Karen Wilson; Adam Lee; Deb Harris; Dave Scapens

doi:10.1016/j.apcatb.2019.118499

Pd-promoted WO₃-ZrO₂ for low temperature NOx storage

Yaying Ji, Shuli Bai, Dongyan Xu, Dali Qian, Zili Wu, Yang Song, Robert Pace, Mark Crocker, Karen Wilson, Adam Lee, Deb Harris, Dave Scapens

Surface Chemistry & Catalysis Group

Research output: Contribution to journal › Article › peer-review

35 Scopus citations

Abstract

Pd-promoted ZrO₂ and 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 ZrO₂ Pd 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.

Original language	English
Article number	118499
Journal	Applied Catalysis B: Environmental
Volume	264
DOIs	https://doi.org/10.1016/j.apcatb.2019.118499
State	Published - May 5 2020

Keywords

Cations
DRIFTS
Nitrosyl complex
Palladium
Passive NOx adsorber
Tungstated zirconia

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10.1016/j.apcatb.2019.118499

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@article{b0808367d36343458bfe57c3014d53bb,

title = "Pd-promoted WO3-ZrO2 for low temperature NOx storage",

abstract = "Pd-promoted ZrO2 and 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 ZrO2 Pd 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.",

keywords = "Cations, DRIFTS, Nitrosyl complex, Palladium, Passive NOx adsorber, Tungstated zirconia",

author = "Yaying Ji and Shuli Bai and Dongyan Xu and Dali Qian and Zili Wu and Yang Song and Robert Pace and Mark Crocker and Karen Wilson and Adam Lee and Deb Harris and Dave Scapens",

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year = "2020",

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doi = "10.1016/j.apcatb.2019.118499",

language = "English",

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T1 - Pd-promoted WO3-ZrO2 for low temperature NOx storage

AU - Ji, Yaying

AU - Bai, Shuli

AU - Xu, Dongyan

AU - Qian, Dali

AU - Wu, Zili

AU - Song, Yang

AU - Pace, Robert

AU - Crocker, Mark

AU - Wilson, Karen

AU - Lee, Adam

AU - Harris, Deb

AU - Scapens, Dave

PY - 2020/5/5

Y1 - 2020/5/5

N2 - Pd-promoted ZrO2 and 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 ZrO2 Pd 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.

AB - Pd-promoted ZrO2 and 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 ZrO2 Pd 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.

KW - Cations

KW - DRIFTS

KW - Nitrosyl complex

KW - Palladium

KW - Passive NOx adsorber

KW - Tungstated zirconia

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U2 - 10.1016/j.apcatb.2019.118499

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JO - Applied Catalysis B: Environmental

JF - Applied Catalysis B: Environmental

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ER -

Pd-promoted WO₃-ZrO₂ for low temperature NOx storage

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Keywords

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