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Catalytic characterization of pure SnO2 and GeO2 in methanol steam reforming

Paper ID Volume ID Publish Year Pages File Format Full-Text
42471 45927 2010 8 PDF Available
Title
Catalytic characterization of pure SnO2 and GeO2 in methanol steam reforming
Abstract

Structural changes of a variety of different SnO, SnO2 and GeO2 catalysts upon reduction in hydrogen were correlated with associated catalytic changes in methanol steam reforming. Studied systems include SnO, SnO2 and GeO2 thin film model catalysts prepared by vapour phase deposition and growth on polycrystalline NaCl surfaces and, for comparison, the corresponding pure oxide powder catalysts.Reduction of both the SnO2 thin film and powder at around 673 K in 1 bar hydrogen leads to a substantial reduction of the bulk structure and yields a mixture of SnO2 and metallic β-Sn. On the powder catalyst this transformation is fully reversible upon oxidation in 1 bar O2 at 673 K. Strongly reduced thin films, however, can only be re-transformed to SnO2 if the reduction temperature did not exceed 573 K. For GeO2, the situation is more complex due to its polymorphism. Whereas the tetragonal phase is structurally stable during reduction, oxidation or catalytic reaction, a small part of the hexagonal phase is always transformed into the tetragonal at 673 K independent of the gas phase used.SnO2 is highly active and CO2 selective in methanol steam reforming, but the initial high activity drops considerably upon reduction between 373 and 573 K and almost complete catalyst deactivation is observed after reduction at 673 K, which is associated with the parallel formation of β-Sn. In close correlation to the structural results, the catalytic activity and selectivity can be restored upon an oxidative catalyst regeneration at 673 K. Tetragonal GeO2 exhibits only a small activity and no pronounced selectivity to either CO or CO2, at least after reduction. In its fully oxidized state release of surface/lattice oxygen results in a non-catalytic formation of CO2 by oxidation of CO originating from catalytic dehydrogenation.

Graphical abstractWe demonstrated the catalytic activity and selectivity of SnO/SnO2 and GeO2 in methanol steam reforming, in close correlation to oxides in the 3rd main group of the periodic system, namely Ga2O3 and In2O3. It was shown that the catalytic selectivity of In2O3 and SnO2 towards CO2 is very pronounced. In contrast, Ga2O3 and GeO2 are less CO2 selective but exhibit very similar reaction profiles.Figure optionsDownload full-size imageDownload high-quality image (77 K)Download as PowerPoint slide

Keywords
Electron microscopy; EELS; SnO2; SnO; GeO2; Methanol steam reforming; CO2 selectivity
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Catalytic characterization of pure SnO2 and GeO2 in methanol steam reforming
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 375, Issue 2, 1 March 2010, Pages 188–195
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