Issue 42, 2020

Low-temperature NO oxidation using lattice oxygen in Fe-site substituted SrFeO3−δ

Abstract

Improvement of the low-temperature activity for NO oxidation catalysts is a crucial issue to improve the NOx storage performance in automotive catalysts. We have recently reported that the lattice oxygen species in SrFeO3−δ (SFO) are reactive in the oxidation of NO to NO2 at low temperatures. The oxidation of NO using lattice oxygen species is a powerful means to oxidize NO in such kinetically restricted temperature regions. This paper shows that Fe-site substitution of SFO with Mn or Co improves the properties of lattice oxygen such as the temperature and amount of oxygen release/storage, resulting in the enhancement of the activity for NO oxidation in a low-temperature range. In particular, NO oxidation on SrFe0.8Mn0.2O3−δ is found to proceed even at extremely low temperatures <423 K. From oxygen release/storage profiles obtained by temperature-programmed reactions, Co doping into SFO increases the amount of released oxygen owing to the reducibility of the Co species and promotes the phase transformation to the brownmillerite phase. On the other hand, Mn doping does not increase the oxygen release amount and suppresses the phase transformation. However, it significantly decreases the oxygen migration barrier of SFO. Substitution with Mn renders the structure of SFO more robust and maintains the perovskite structure after the release of oxygen. Thus, the oxygen release properties are strongly dependent on the crystal structure change before and after oxygen release from the perovskite structure, which has a significant effect on NO oxidation and the NOx storage performance.

Graphical abstract: Low-temperature NO oxidation using lattice oxygen in Fe-site substituted SrFeO3−δ

Supplementary files

Article information

Article type
Paper
Submitted
13 Jul 2020
Accepted
07 Sep 2020
First published
08 Sep 2020

Phys. Chem. Chem. Phys., 2020,22, 24181-24190

Low-temperature NO oxidation using lattice oxygen in Fe-site substituted SrFeO3−δ

K. Tamai, S. Hosokawa, K. Kato, H. Asakura, K. Teramura and T. Tanaka, Phys. Chem. Chem. Phys., 2020, 22, 24181 DOI: 10.1039/D0CP03726E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements