Issue 11, 2020

Mechanistic insights into the oxidation of copper(i) species during NH3-SCR over Cu-CHA zeolites: a DFT study

Abstract

Selective catalytic reduction of nitrogen oxides using ammonia (NH3-SCR) over Cu-exchanged zeolites proceeds via reduction of Cu(II) to Cu(I) and subsequent reoxidation of Cu(I) to Cu(II). Although the mechanism of reduction half cycle has been relatively well established, reoxidation pathways of Cu(I) to form the original Cu(II) species are highly complicated and remain unclear. Herein, oxidation mechanisms of Cu(I) to Cu(II) species in CHA zeolites during the NH3-SCR process were investigated by periodic DFT calculations. The NH3-solvated Cu(I) and Cu(II) species were considered for exploring the oxidative activation reaction pathways. The results show that, with O2 as the sole oxidant, Cu(I) can be effectively oxidized to Cu(II) via multinuclear Cu-oxo intermediates with moderate reaction barriers. The NO-assisted oxidation of Cu(I) was found to favor the formation of Cu nitrate/nitrite species, which seem to only act as off-cycle resting states. We propose that reoxidation of Cu(I) to Cu(II) with O2 as the sole oxidant plays a key role in the oxidation half cycle under standard NH3-SCR conditions.

Graphical abstract: Mechanistic insights into the oxidation of copper(i) species during NH3-SCR over Cu-CHA zeolites: a DFT study

Supplementary files

Article information

Article type
Paper
Submitted
27 ፌብሩ 2020
Accepted
27 ኤፕሪ 2020
First published
28 ኤፕሪ 2020

Catal. Sci. Technol., 2020,10, 3586-3593

Author version available

Mechanistic insights into the oxidation of copper(I) species during NH3-SCR over Cu-CHA zeolites: a DFT study

C. Liu, H. Kubota, T. Toyao, Z. Maeno and K. Shimizu, Catal. Sci. Technol., 2020, 10, 3586 DOI: 10.1039/D0CY00379D

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