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EXAFS, XPS and TEM Characterization of SnO2-Based Emission Control Catalysts

Published online by Cambridge University Press:  15 February 2011

Philip G. Harrison ,
Wayne Daniel ,
Nicholas C. Lloyd  and
Wan Azelee
Philip G. Harrison
Affiliation:
Department of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
Wayne Daniel
Affiliation:
Department of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
Nicholas C. Lloyd
Affiliation:
Department of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
Wan Azelee
Affiliation:
Department of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
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Abstract

Catalysts formed by sorption of Cr(VI) on to tin(IV) oxide have been investigated by EXAFS, XPS and TEM. The latter shows that uncalcined catalysts comprise uniform, homogeneous particles of dimensions 2nm which increase to 4nm on calcination at 400°C. Calcination at higher temperatures results in an increase in particle size to 20nm × 30nm at 600°C, ca. 60nm at 800°C, and 90–100nm at 1000°C. XPS data show the evolution of chromium(III) species upon calcination and both chromium(VI) and chromium(III) species exist at all calcination temperatures. Chromium K-edge XANES also shows the presence of tetrahedral chromium(VI) species at all calcination temperatures, but the relative abundance decreases with increase in calcination temperature. Corresponding EXAFS data indicate that the uncalcined catalyst contains sorbed four-coordinated {Cr2O7} species whereas calcination produces six-coordinated {CrO6} species together with some residual tetrahedrally coordinated chromium. EXAFS data show that adsorbed {Cu(H2O)6} is the copper(II) species present prior to calcination of CuII-SnO2 catalysts.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 368: Symposium T – Synthesis and Properties of Advanced Catalytic Materials , 1994 , 255
Copyright
Copyright © Materials Research Society 1995

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References

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