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

Research output: Contribution to journalArticlepeer-review

32 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 languageEnglish
Article number118499
JournalApplied Catalysis B: Environmental
Volume264
DOIs
StatePublished - May 5 2020

Bibliographical note

Funding Information:
The authors thank Shelley Hopps for XRD measurements. Drs. Christine Lambert and Joe Theis of Ford Motor Co. are thanked for helpful discussions. This project was funded by the National Science Foundation and the U.S. Department of Energy (DOE) under award no. CBET-1258742. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the DOE. Funding from the British Council under the Global Innovation Initiative for the GB 3 -Net project is also gratefully acknowledged. Dr. Zili Wu was supported by the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), an Energy Frontier Research Center funded by U.S. Department of Energy, Office of Science, Basic Energy Sciences . The Raman work was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. Appendix A

Funding Information:
The authors thank Shelley Hopps for XRD measurements. Drs. Christine Lambert and Joe Theis of Ford Motor Co. are thanked for helpful discussions. This project was funded by the National Science Foundation and the U.S. Department of Energy (DOE) under award no. CBET-1258742. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the DOE. Funding from the British Council under the Global Innovation Initiative for the GB3-Net project is also gratefully acknowledged. Dr. Zili Wu was supported by the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), an Energy Frontier Research Center funded by U.S. Department of Energy, Office of Science, Basic Energy Sciences. The Raman work was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Publisher Copyright:
© 2019 Elsevier B.V.

Keywords

  • Cations
  • DRIFTS
  • Nitrosyl complex
  • Palladium
  • Passive NOx adsorber
  • Tungstated zirconia

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science (all)
  • Process Chemistry and Technology

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