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Methane decomposition over Ni–MgO–Al2O3 catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
42793 45941 2009 8 PDF Available
Title
Methane decomposition over Ni–MgO–Al2O3 catalysts
Abstract

Studies of methane decomposition were performed over nickel alumina catalysts modified with magnesia. The catalysts were obtained by the co-precipitation method. The properties of catalysts were investigated by the temperature programmed reduction (TPR) and hydrogen desorption (TPD) methods. Methane decomposition was studied by the thermogravimetric and transient temperature programmed reaction methods. The nature of carbon deposits formed under different reaction conditions was investigated by the temperature programmed oxidation method (TPO) and high resolution transmission electron microscopy (HRTEM). An introduction of magnesium to the preparation mixture of catalysts led to the formation of smaller nickel crystallites with stronger adsorption sites. It was found out that the activity of catalysts and the properties of carbon deposits were related to the catalysts composition and the reaction temperature. Carbon filaments with fishbone-like packed graphitic layers were formed at 500 °C, while the multi-walled nanotubes were observed after reaction performed at 700 °C. The increase of magnesium content led to the increase of the rate of methane decomposition at the initial stages of the reaction. Deactivation of the catalysts was related to the insufficient removal of carbon species from the surface of nickel crystallites and the formation of stable, graphitic carbon deposits covering the surface of metal.

Graphical abstractMethane decomposition was studied over nickel–magnesia–alumina catalyst. An increase of the reaction temperature caused transformation of the carbon filaments with fishbone-like graphitic layers to the multi-walled nanotubes with nickel crystallites located on the tip. The deactivation of the catalysts was related to the insufficient removal of the stable carbon deposits from the surface of nickel crystallites.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Hydrogen; Carbon nanomaterials; Nickel catalyst; Deactivation; HRTEM
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Methane decomposition over Ni–MgO–Al2O3 catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 357, Issue 2, 15 April 2009, Pages 236–243
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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Full-text PDF Download
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