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Oxidation of CO over Ru containing perovskite type oxides

Paper ID Volume ID Publish Year Pages File Format Full-Text
49104 46549 2006 9 PDF Available
Title
Oxidation of CO over Ru containing perovskite type oxides
Abstract

Perovskite type catalysts La0.7Sr0.3Cr1−xRuxO3 (0.025 ≤ x ≤ 0.100) were synthesized by annealing a mixture of metal oxides and carbonates gradually up to 1000 °C in air, and characterized by XRPD, XPS, TPD, SEM-EDS and the van der Pauw method. The CO oxidation activity was investigated in a differential recycle reactor. According to the XRPD results, all samples achieved a perovskite structure, with a small presence of SrCrO4 phase. The XPS results revealed that the surface composition of all samples differed considerably from the stoichiometric value with an important segregation of strontium and mainly ruthenium with regard to chromium at the surface of the catalysts. The sharp decrease of resistivity with increasing surface concentration of ruthenium and the independence of the resistivity on temperature for the sample with x = 0.100 imply the possible presence of SrRuO3, La–Ru–O and highly dispersed RuO2 (invisible by XRPD), known as good electric conductors, at the surface. The CO oxidation activity increases with increasing the degree of substitution (x). The surface concentrations of ruthenium are almost the same in the samples with x = 0.075 and 0.100. Those samples showed the similar values of resistivity in whole investigated temperature range and very close CO oxidation activity, which indicates that the concentration of Ru4+ in the surface region and its stability are determining factors for the CO oxidation activity. The main results of this study are that ruthenium perovskites have a high thermal stability and CO oxidation activity.

Keywords
Ruthenium; Perovskite; Electric resistivity; CO oxidation activity
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 66, Issues 3–4, 20 July 2006, Pages 249–257
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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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
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