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Dynamic active sites over binary oxide catalysts: In situ/operando spectroscopic study of low-temperature CO oxidation over MnOx-CeO2 catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
44818 46360 2016 13 PDF Available
Title
Dynamic active sites over binary oxide catalysts: In situ/operando spectroscopic study of low-temperature CO oxidation over MnOx-CeO2 catalysts
Abstract

•A binary oxide MnOx-CeO2 showed excellent activity for low-temperature CO oxidation.•The dynamic structures of MnOx-CeO2 were determined by operando spectroscopies.•Mars-van Krevelen mechanism was proceeded for CO oxidation over MnOx-CeO2.•The direct and the formate routes were followed at T < 130 °C.•The carbonate route became dominant at T > 130 °C.

The determination of the dynamic active sites over binary oxide catalysts is of great challenge in heterogeneous catalysis. In this work, the origin of active sites toward low-temperature CO oxidation (<200 °C) were thoroughly studied using MnOx-CeO2 composite oxide catalysts with different Mn/Ce molar ratios, synthesized by a redox co-precipitation method. The optimum Mn1Ce1 catalyst (T100 = 190 °C), which showed excellent activity, has found to be composed of three phases: (1) CeO2; (2) amorphous MnOx; (3) MnOx-CeO2 solid solution (active sites). With the combination of kinetics and characterization results, including Temperature-Programmed-Desorption/Reduction (TPD/TPR), operando Raman spectroscopy and in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS), the dynamic structures of catalysts were rationalized with the identification of the interface of MnOx and CeO2. The mechanism for CO oxidation over MnOx-CeO2 in the temperature range 100–190 °C were proposed that the direct and the formate routes were followed at T < 130 °C, and the carbonate route became dominant at T > 130 °C. Notably, the Mars-van Krevelen mechanism was proceeded in the whole temperature range. We speculate that cheap binary oxides will substitute for noble metal as catalysts for the removal of CO and other toxic gases, especially operating under mild conditions.

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Keywords
Dynamic structure; Binary oxide; MnOx-CeO2; CO oxidation; Operando spectroscopy
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Dynamic active sites over binary oxide catalysts: In situ/operando spectroscopic study of low-temperature CO oxidation over MnOx-CeO2 catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 191, 15 August 2016, Pages 179–191
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us