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A Comparison Between the Structural and Catalytic Properties of Supported W2C, WC and WC1−x

Published online by Cambridge University Press:  10 February 2011

Saemin Choi  and
Levi T. Thompson
Saemin Choi
Affiliation:
University of Michigan, Department of Chemical Engineering, Ann Arbor, MI 48109–2136, USA
Levi T. Thompson
Affiliation:
University of Michigan, Department of Chemical Engineering, Ann Arbor, MI 48109–2136, USA
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Abstract

A series of γ-Al2O3 and SiO2 supported tungsten carbides was synthesized by the temperature programmed reaction of supported tungstates with CH4/H2 mixtures. The three known phases, W2C, WC and WC1−x, were evaluated as butane dehydrogenation catalysts. The microstructure and composition of the supported carbides depended on the loading and final synthesis temperature. The low and medium loaded materials were x-ray amorphous suggesting highly dispersed carbide domains on the support. The high loaded materials possessed small crystallites of W2C, WC or WC1-x. The supported carbides were as active as a commercial dehydrogenation catalyst with comparable selectivities in several cases. The butane conversion activity decreased in the following order: W2C > WC > WC1-x. The dehydrogenation selectivity decreased as the activity increased. The results suggest that there were two different types of sites, those catalyzing the selective dehydrogenation of butane and those capable of butane hydrogenolysis. The activity of these latter sites declined significantly with time on stream. We believe the hydrogenolysis activity was due to acid sites on the supported carbides.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 454: Symposium S – Advanced Catalytic Materials–1996 , 1996 , 41
Copyright
Copyright © Materials Research Society 1997

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References

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