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Decomposition of Al2O3-Supported PdSO4 and Al2(SO4)3 in the Regeneration of Methane Combustion Catalyst: A Model Catalyst Study

Authors :
Niko M. Kinnunen
Ville H. Nissinen
Janne T. Hirvi
Kauko Kallinen
Teuvo Maunula
Matthew Keenan
Mika Suvanto
Source :
Catalysts, Vol 9, Iss 5, p 427 (2019)
Publication Year :
2019
Publisher :
MDPI AG, 2019.

Abstract

Exhaust gas aftertreatment systems play a key role in controlling transportation greenhouse gas emissions. Modern aftertreatment systems, often based on Pd metal supported on aluminum oxide, provide high catalytic activity but are vulnerable to sulfur poisoning due to formation of inactive sulfate species. This paper focuses on regeneration of Pd-based catalyst via the decomposition of alumina-supported aluminum and palladium sulfates existing both individually and in combination. Decomposition experiments were carried out under hydrogen (10% H2/Ar), helium (He), low oxygen (0.1% O2/He), and excess oxygen (10% O2/He). The structure and composition of the model catalysts were examined before and after the decomposition reactions via powder X-ray diffraction and elemental sulfur analysis. The study revealed that individual alumina-supported aluminum sulfate decomposed at a higher temperature compared to individual alumina-supported palladium sulfate. The simultaneous presence of aluminum and palladium sulfates on the alumina support decreased their decomposition temperatures and led to a higher amount of metallic palladium than in the corresponding case of individual supported palladium sulfate. From a fundamental point of view, the lowest decomposition temperature was achieved in the presence of hydrogen gas, which is the optimal decomposition atmosphere among the studied conditions. In summary, aluminum sulfate has a two-fold role in the regeneration of a catalyst—it decreases the Pd sulfate decomposition temperature and hinders re-oxidation of less-active metallic palladium to active palladium oxide.

Details

Language :
English
ISSN :
20734344
Volume :
9
Issue :
5
Database :
Directory of Open Access Journals
Journal :
Catalysts
Publication Type :
Academic Journal
Accession number :
edsdoj.6b12dde863f248ed8da1b0b77df43cee
Document Type :
article
Full Text :
https://doi.org/10.3390/catal9050427