Insights into the Contribution of Oxidation-Reduction Pretreatment for Mn0.2Zr0.8O2−δ Catalyst of CO Oxidation Reaction

Insights into the Contribution of Oxidation-Reduction Pretreatment for Mn0.2Zr0.8O2−δ Catalyst of CO Oxidation Reaction Full article

Journal

Materials
ISSN: 1996-1944

Output data

Year: 2023, Volume: 16, Number: 9, Article number : 3508, Pages count : 16 DOI: 10.3390/ma16093508

Tags

Zr-Mn-solid solution; operando XRD; exsolution; Mn surface enrichment; zirconia; CO oxidation reaction

Authors

Mishchenko Denis D. ^1,2 , Vinokurov Zakhar S. ^1,2 , Afonasenko Tatyana N. ³ , Saraev Andrey A. ^1,2 , Simonov Mikhail N. ¹ , Gerasimov Evgeny Yu. ¹ , Bulavchenko Olga A. ¹

Affiliations

1	Boreskov Institute of Catalysis SB RAS, Lavrentiev Ave., 5, Novosibirsk 630090, Russia;
2	Synchrotron Radiation Facility SKIF, Boreskov Institute of Catalysis SB RAS, Nikol’skiy Prospekt 1, Kol’tsovo 630559, Russia
3	Center of New Chemical Technologies, Boreskov Institute of Catalysis SB RAS, Neftezavodskaya, 54, Omsk 644040, Russia

Funding (1)

Russian Science Foundation

21-73-10218 (122051600004-3)

A Mn0.2Zr0.8O2−δ mixed oxide catalyst was synthesized via the co-precipitation method and studied in a CO oxidation reaction after different redox pretreatments. The surface and structural properties of the catalyst were studied before and after the pretreatment using XRD, XANES, XPS, and TEM techniques. Operando XRD was used to monitor the changes in the crystal structure under pretreatment and reaction conditions. The catalytic properties were found to depend on the activation procedure: reducing the CO atmosphere at 400–600 °C and the reaction mixture (O2 excess) or oxidative O2 atmosphere at 250–400 °C. A maximum catalytic effect characterized by decreasing T50 from 193 to 171 °C was observed after a reduction at 400 °C and further oxidation in the CO/O2 reaction mixture was observed at 250 °C. Operando XRD showed a reversible reduction-oxidation of Mn cations in the volume of Mn0.2Zr0.8O2−δ solid solution. XPS and TEM detected the segregation of manganese cations on the surface of the mixed oxide. TEM showed that Mn-rich regions have a structure of MnO2. The pretreatment caused the partial decomposition of the Mn0.2Zr0.8O2−δ solid solution and the formation of surface Mn-rich areas that are active in catalytic CO oxidation. In this work it was shown that the introduction of oxidation-reduction pretreatment cycles leads to an increase in catalytic activity due to changes in the origin of active states.

Mishchenko D.D. , Vinokurov Z.S. , Afonasenko T.N. , Saraev A.A. , Simonov M.N. , Gerasimov E.Y. , Bulavchenko O.A.
Insights into the Contribution of Oxidation-Reduction Pretreatment for Mn0.2Zr0.8O2−δ Catalyst of CO Oxidation Reaction
Materials. 2023. V.16. N9. 3508 :1-16. DOI: 10.3390/ma16093508 WOS Scopus РИНЦ OpenAlex

Submitted:	Mar 31, 2023
Accepted:	Apr 28, 2023
Published print:	May 2, 2023
Published online:	May 2, 2023

Web of science:	WOS:000987653300001
Scopus:	2-s2.0-85159360993
Elibrary:	53962825
OpenAlex:	W4368377186

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