fulltext.study @t Gmail

Methanol steam reforming: CO2-selective Pd2Ga phases supported on α- and γ-Ga2O3

Paper ID Volume ID Publish Year Pages File Format Full-Text
40378 45852 2013 11 PDF Available
Title
Methanol steam reforming: CO2-selective Pd2Ga phases supported on α- and γ-Ga2O3
Abstract

A set of different Pd/Ga2O3 catalysts has been tested as suitable CO2-selective catalysts in methanol steam reforming, formaldehyde steam reforming and formic acid decomposition. Special focus was put on two different polymorphic forms of Ga2O3, namely α-Ga2O3 and γ-Ga2O3 and their comparison to the use of the more common β-Ga2O3 as oxide support of small Pd particles. The formation of eventually CO2-selective intermetallic Pd–Ga phases started at around 523 K on both supports. Pd2Ga at low temperatures (between 523 K and 673 K) and generally PdGa at higher temperatures (at and above 673 K) were the only intermetallic phases observed. Both thermodynamically metastable oxide supports transformed into the stable β-Ga2O3 structure at 873 K reduction temperature. In contrast to previous studies, a highly CO2-selective state in methanol steam reforming (CO2 selectivity > 70%) could be established on both catalysts after reduction at 673 K (α-Ga2O3) and 523 K (γ-Ga2O3), where the active state of the catalysts can be characterised as Pd2Ga/α-Ga2O3 and Pd2Ga/γ-Ga2O3, respectively. α-Ga2O3 itself is reasonably CO2-selective in methanol steam reforming (∼80%), although not very active. In contrast, the γ-Ga2O3 polymorph is neither CO2-selective, nor active and resembles the behaviour of β-Ga2O3. The high CO2-selectivity of α-Ga2O3 is explained in terms of a higher surface basicity alongside efficient decarboxylation of intermediary formed formic acid. As crucial parameters for the observed CO2-selectivity in methanol steam reforming, decarboxylation of formic acid and oxidation of formaldehyde proceeding efficiently via a low-temperature reaction channel over either oxide-supported Pd2Ga intermetallic catalysts were identified.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (264 K)Download as PowerPoint slideHighlights► Formation of catalytically active intermetallic Pd2Ga phases on α-Ga2O3 and γ-Ga2O3. ► CO2-selective state in methanol steam reforming after entering the intermetallic state. ► Polymorph-dependent catalytic performance in methanol steam reforming. ► Reduction of Ga2O3 polymorphs has no influence on the catalytic performance. ► A bi-functional synergism between Pd2Ga phase and support is prevalent.

Keywords
Intermetallic compounds; Formic acid decomposition; X-ray diffraction; CO2 selectivity; Pd2Ga
First Page Preview
Methanol steam reforming: CO2-selective Pd2Ga phases supported on α- and γ-Ga2O3
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 453, 26 February 2013, Pages 34–44
Authors
, , , , , , , , , ,
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