fulltext.study @t Gmail

Metal dispersion, accessibility and catalytic activity in methane oxidation of mesoporous templated aluminosilica supported palladium

Paper ID Volume ID Publish Year Pages File Format Full-Text
40113 45844 2013 12 PDF Available
Title
Metal dispersion, accessibility and catalytic activity in methane oxidation of mesoporous templated aluminosilica supported palladium
Abstract

•A modified TIE metal deposition technique leads to high palladium dispersion for high loading.•Partial channel collapse leads to more open structures correlated to higher catalytic activity.•Metal encapsulation in silica-alumina support provokes a loss of catalytic activity in MCM-41.•Effect of aluminum and, metal dispersion and accessibility on catalytic activity is discussed.•Better catalysts than the classical Pd/Al2O3 catalysts are obtained for methane oxidation.

Palladium catalysts using templated mesostructured porous silicas and aluminosilicas of MCM-41 type as supports were synthesized with various metal loadings and particle sizes as well as different metal accessibilities to the reactants. The metal was deposited by reacting an aqueous solution of [Pd(NH3)4]2+ complexes with the support, the template of which was partially extracted. The evolution of the support characteristics was monitored at different steps of preparation using X-ray diffraction (XRD), N2 physisorption and transmission electron microscopy (TEM). Particle size and metal accessibility were evaluated combining information from XRD line broadening, TEM observations, UV–visible spectra and H2 uptakes. The PdO reducibility was investigated using temperature-programmed reduction (TPR). In the templated mesoporous aluminosilicate, 27Al-MAS-NMR revealed that Al3+ occupied mostly tetrahedral sites, a fraction of which adopted an octahedral environment in the presence of palladium. According to the light-off curves, the catalytic methane oxidation activity is enhanced in pure silica supports where partial pore wall collapse has occurred. In contrast, for aluminosilica supports the beneficial effect of Al3+ on metal dispersion and catalytic activity was counterbalanced by partial metal encapsulation. Optimizing palladium particle size and avoiding as much as possible metal encapsulation give rise to catalysts more active than the conventional alumina supported palladium catalysts.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (414 K)Download as PowerPoint slide

Keywords
Mesoporous aluminosilicate; MCM-41; Palladium; Template ion exchange; Methane; Catalysis
First Page Preview
Metal dispersion, accessibility and catalytic activity in methane oxidation of mesoporous templated aluminosilica supported palladium
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 - Volumes 464–465, 15 August 2013, Pages 116–127
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