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Conditioning of Rh/α-Al2O3 catalysts for H2 production via CH4 partial oxidation at high space velocity

Paper ID Volume ID Publish Year Pages File Format Full-Text
48837 46522 2007 10 PDF Available
Title
Conditioning of Rh/α-Al2O3 catalysts for H2 production via CH4 partial oxidation at high space velocity
Abstract

Experimental evidence and literature indications suggest that the process of methane partial oxidation over Rh catalysts is structure sensitive. Crystal phases and Rh cluster size are thus expected to affect the final catalytic performance. In this work, it is observed that outstanding performances are obtained when the as-prepared catalysts are conditioned through repeated runs at increasing temperature and O2/CH4 = 0.56. Catalysts slowly activate, that is CH4 conversion and synthesis gas selectivity progressively grow with time on stream. On the basis of TPO and CH4 decomposition measurements, this phenomenon is herein explained as the result of a surface reconstruction driven by the repeated exposition to the reaction at high temperature; it is thought that such reconstruction tends to eliminate defect sites and disfavors C-deposition reactions (extremely fast over steps and kinks). Conditioning with O2-enriched feed streams makes conditioning faster, since the accumulation of surface C-species is suppressed; however, the catalyst is eventually less active than a catalyst conditioned with standard feed mixtures. As an alternative, accumulation of carbon can be suppressed and surface reconstruction proceeds faster if the catalyst is directly exposed to the reaction at high temperature for several hours.

Keywords
CH4 partial oxidation; Rh/α-Al2O3; Rh reconstruction; Structure sensitivity of C–H bond activation
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Conditioning of Rh/α-Al2O3 catalysts for H2 production via CH4 partial oxidation at high space velocity
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 70, Issues 1–4, 31 January 2007, Pages 515–524
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