Highly active Co-Al2O3-based catalysts for CO2 methanation with very low platinum promotion prepared by double flame spray pyrolysis

Cobalt-based catalysts are often promoted with noble metals to improve the reducibility of the catalyst and provide a high number of metallic Co sites. The high cost of such noble metals requires new synthetic strategies enabling the use of such promoters at as low concentrations as possible. In thi...

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Bibliographic Details
Published in:Catalysis science & technology 2016-01, Vol.6 (20), p.7449-7460
Main Authors: Schubert, Miriam, Pokhrel, Suman, Thome, Andreas, Zielasek, Volkmar, Gesing, Thorsten M, Roessner, Frank, Maedler, Lutz, Baeumer, Marcus
Format: Article
Language:English
Subjects:
Carbon dioxide
Catalysis
Catalysts
Cobalt
Methanation
Noble metals
Platinum
Reduction
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Summary:Cobalt-based catalysts are often promoted with noble metals to improve the reducibility of the catalyst and provide a high number of metallic Co sites. The high cost of such noble metals requires new synthetic strategies enabling the use of such promoters at as low concentrations as possible. In this article, we present platinum-promoted Co-Al2O3 catalysts with very small concentrations of platinum (between 0.03 and 0.43 wt%) synthesized by double flame spray pyrolysis (DFSP) as a very versatile preparation technique. Catalysts with Pt contents as low as 0.03 wt% Pt lead to a significant improvement in the reducibility of Co3O4 and to high catalytic activity for the CO2 methanation reaction compared to non-promoted Co-Al2O3. Upon further increasing the Pt content up to 0.43 wt%, only a slight improvement in catalyst reduction and catalytic activity is observed. All prepared catalysts were characterised using XRD, BET, TPR, TEM and EDX followed by catalytic tests for CO2 methanation. Furthermore, two different preparation schemes were used for DFSP, where platinum was combusted either with Co or with the Al precursor solution in one flame, which results in catalysts with a tight chemical contact between Pt and Co3O4 or Pt and Al2O3, respectively. Based on TPR and catalytic tests it could be demonstrated that the deposition of platinum on one or the other oxidic phase has no influence on the reducibility and catalytic performance. The conversion and reducibility were similar for both preparation schemes, an observation which can be explained by H2 spillover during catalyst reduction and catalytic reaction.
ISSN:2044-4753
2044-4761
DOI:10.1039/c6cy01252c