Comparative study of structure-catalytic activity relationship for Ni–Cr–Al–O and Cu–Ni–Cr–Al–O spinel oxide solid solutions

Taiki HIRAKAWA; Wakana TOKUZUMI; Yushi SHIMOKAWA; Tetsuya SATO; Hiroshi YOSHIDA; Junya OHYAMA; Masato MACHIDA

doi:10.2109/jcersj2.20101

Feature: The 58^th Symposium on Basic Science of Ceramics: Full papers

Comparative study of structure-catalytic activity relationship for Ni–Cr–Al–O and Cu–Ni–Cr–Al–O spinel oxide solid solutions

Taiki HIRAKAWA, Wakana TOKUZUMI, Yushi SHIMOKAWA, Tetsuya SATO, Hiroshi YOSHIDA, Junya OHYAMA, Masato MACHIDA

Author information

Taiki HIRAKAWA
Department of Applied Chemistry and Biochemistry, Graduate School of Science and Technology, Kumamoto University
Wakana TOKUZUMI
Department of Applied Chemistry and Biochemistry, Graduate School of Science and Technology, Kumamoto University
Yushi SHIMOKAWA
Department of Applied Chemistry and Biochemistry, Graduate School of Science and Technology, Kumamoto University
Tetsuya SATO
Technical Division, Faculty of Engineering, Kumamoto University
Hiroshi YOSHIDA
Division of Materials Science and Chemistry, Faculty of Advanced Science and Technology, Kumamoto University
Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University
Junya OHYAMA
Division of Materials Science and Chemistry, Faculty of Advanced Science and Technology, Kumamoto University
Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University
Masato MACHIDA
Division of Materials Science and Chemistry, Faculty of Advanced Science and Technology, Kumamoto University
Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University

Keywords: Spinel oxide, Solid solution, Site preference, NO reduction, Catalyst

JOURNAL FREE ACCESS

2020 Volume 128 Issue 11 Pages 906-911

DOI https://doi.org/10.2109/jcersj2.20101

Details

Abstract

A spinel solid solution expressed by a composition formula of Cu_xNi₁₋_xAl_1.8Cr_0.2O₄ (0 ≤ x ≤ 0.2) was studied focusing on the role of Cu species in the catalytic activity toward NO reduction under a simulated three-way catalysis condition. X-ray Rietveld analysis revealed that Cu and Cr prefer to occupy the tetrahedral site and the octahedral site, respectively, whereas Ni and Al are distributed across both sites. Although NiAl_1.8Cr_0.2O₄ (x = 0) showed negligible catalytic activity for NO reduction, the partial replacement of Ni by Cu significantly enhanced the activity, achieving the highest activity at x = 0.05 not only for NO reduction but also for CO and C₃H₆ oxidation. Based on the infrared spectra and pulsed reaction experiments, it was concluded that the monovalent Cu site in the tetrahedral site plays a key role in CO chemisorption, oxygen vacancy formation, and subsequent NO reduction via the Mars–van Krevelen mechanism.

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