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Particle development and characterisation in Pt(acac)(2) and Pt(acac)(2)/GeBu4 derived catalysts supported upon porous and mesoporous SiO2: effect of reductive environment, and support structure

Particle development and characterisation in Pt(acac)(2) and Pt(acac)(2)/GeBu4 derived catalysts supported upon porous and mesoporous SiO2: effect of reductive environment, and support structure
Particle development and characterisation in Pt(acac)(2) and Pt(acac)(2)/GeBu4 derived catalysts supported upon porous and mesoporous SiO2: effect of reductive environment, and support structure
In situ, time resolved energy dispersive EXAFS (EDE) has been used in conjunction with temperature programmed reduction/decomposition (TPR/TPD), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and diffuse reflectance infrared spectroscopy (DRIFTS) to probe the evolution and character of Pt and PtGe alloy particles, derived from Pt(acac)(2) and GeBu4 precursors, supported upon amorphous and mesoporous silicas. The reduction kinetics and final particle size distributions obtained are found to be functions of the reductive environment, the support architecture, and the presence of GeBu4. Reduction of the Pt-only systems in H-2 is found to have an autocatalytic character resulting in the rapid formation of large (N1Pt–Pt>8) particles at ca. 390 K. Reduction in the absence of hydrogen and/or in the presence of co-adsorbed GeBu4, results in a considerable retardation of particle growth and shows a dependence upon the support architecture. Both EDE and DRIFTS show that, in the case of PtGe alloy system elemental Pt particles form first (in the region of 400-500 K) and it is only at temperatures in excess of 500 K that significant alloy (Pt3Ge) formation is observed along with a concomitant reduction in average particle size. This same pattern of behaviour is also observed when Pt particles are pre-formed prior to the introduction of GeBu4 and subsequent reduction. These results are discussed in terms of the reductive processes at work in these systems, the support architecture, and the effects of retained carbonaceous materials on developing particles.
energy-dispersive exafs, curved-wave theory, reforming catalysts, carbon-monoxide, platinum, pt(111), co, dehydrogenation, precursors, timescale
1463-9076
827-834
Fiddy, Steven G.
f6c255cf-6aa1-4798-85ca-1a2ccdaa1186
Newton, M.A.
cf7f71a3-7c53-46f4-bf2d-9c02e0f2eda0
Campbell, Tom
57689594-8890-4064-b0e0-3eae0099a6b0
Dent, Andrew J.
24c2a218-cb0e-4193-af0b-3ff1dc42b552
Harvey, Ian
c7d85326-0c7a-47b5-a50b-fd6bfebbe3cd
Salvini, Guiseppe
0cbc18c5-ec2f-40c5-83c9-ee72b58c6cd9
Turin, Sandra
05890433-0155-49fe-a65d-38c90ea25c69
Fiddy, Steven G.
f6c255cf-6aa1-4798-85ca-1a2ccdaa1186
Newton, M.A.
cf7f71a3-7c53-46f4-bf2d-9c02e0f2eda0
Campbell, Tom
57689594-8890-4064-b0e0-3eae0099a6b0
Dent, Andrew J.
24c2a218-cb0e-4193-af0b-3ff1dc42b552
Harvey, Ian
c7d85326-0c7a-47b5-a50b-fd6bfebbe3cd
Salvini, Guiseppe
0cbc18c5-ec2f-40c5-83c9-ee72b58c6cd9
Turin, Sandra
05890433-0155-49fe-a65d-38c90ea25c69

Fiddy, Steven G., Newton, M.A., Campbell, Tom, Dent, Andrew J., Harvey, Ian, Salvini, Guiseppe and Turin, Sandra (2002) Particle development and characterisation in Pt(acac)(2) and Pt(acac)(2)/GeBu4 derived catalysts supported upon porous and mesoporous SiO2: effect of reductive environment, and support structure. Physical Chemistry Chemical Physics, 4 (5), 827-834. (doi:10.1039/b108545j).

Record type: Article

Abstract

In situ, time resolved energy dispersive EXAFS (EDE) has been used in conjunction with temperature programmed reduction/decomposition (TPR/TPD), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and diffuse reflectance infrared spectroscopy (DRIFTS) to probe the evolution and character of Pt and PtGe alloy particles, derived from Pt(acac)(2) and GeBu4 precursors, supported upon amorphous and mesoporous silicas. The reduction kinetics and final particle size distributions obtained are found to be functions of the reductive environment, the support architecture, and the presence of GeBu4. Reduction of the Pt-only systems in H-2 is found to have an autocatalytic character resulting in the rapid formation of large (N1Pt–Pt>8) particles at ca. 390 K. Reduction in the absence of hydrogen and/or in the presence of co-adsorbed GeBu4, results in a considerable retardation of particle growth and shows a dependence upon the support architecture. Both EDE and DRIFTS show that, in the case of PtGe alloy system elemental Pt particles form first (in the region of 400-500 K) and it is only at temperatures in excess of 500 K that significant alloy (Pt3Ge) formation is observed along with a concomitant reduction in average particle size. This same pattern of behaviour is also observed when Pt particles are pre-formed prior to the introduction of GeBu4 and subsequent reduction. These results are discussed in terms of the reductive processes at work in these systems, the support architecture, and the effects of retained carbonaceous materials on developing particles.

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More information

Published date: 2002
Keywords: energy-dispersive exafs, curved-wave theory, reforming catalysts, carbon-monoxide, platinum, pt(111), co, dehydrogenation, precursors, timescale

Identifiers

Local EPrints ID: 19732
URI: http://eprints.soton.ac.uk/id/eprint/19732
ISSN: 1463-9076
PURE UUID: 4c69ef65-da32-468e-a426-6055451003e6

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Date deposited: 17 Feb 2006
Last modified: 08 Jan 2022 09:50

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Contributors

Author: Steven G. Fiddy
Author: M.A. Newton
Author: Tom Campbell
Author: Andrew J. Dent
Author: Ian Harvey
Author: Guiseppe Salvini
Author: Sandra Turin

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