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Open AccessArticle

Thermal Stability of Nanoporous Raney Gold Catalyst

Institute for Nanoscale Technology, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia
Department of Engineering and Technology Management, University of Pretoria, Lynnwood Road, Hatfield, Pretoria 0002, South Africa
Author to whom correspondence should be addressed.
Academic Editors: Eva Pellicer and Jordi Sort Viñas
Metals 2015, 5(3), 1197-1211;
Received: 17 June 2015 / Revised: 27 June 2015 / Accepted: 1 July 2015 / Published: 7 July 2015
(This article belongs to the Special Issue Nanoporous Metallic Alloys)
Nanoporous “Raney gold” sponge was prepared by de-alloying an Au-Al precursor alloy. Catalytic tests using a micro-reactor confirmed that Raney gold can serve as an active heterogeneous catalyst for CO oxidation, reduction of NO to N2, and oxidation of NO to NO2. In general, the specific surface area of a heterogeneous catalyst has an influence on its catalytic efficacy. Unfortunately, gold sponges coarsen readily, leading to sintering of their structure and reduction in surface area. This potentially places constraints on their upper operating temperature in catalytic reactors. Here we analyzed the behavior of Raney gold when the temperature was raised. We examined the kinetics and mechanism of coarsening of the sponge using a combination of in situ optical measurements and Metropolis Monte Carlo modeling with a Lennard-Jones interatomic potential. Modeling showed that the sponges started with an isotropic “foamy” morphology with negative average “mean curvature” but that subsequent thermally activated coarsening will drive the morphology through a bi-continuous fibrous state and on, eventually, to a sponge consisting of sintered blobs of predominantly positive “mean curvature”. View Full-Text
Keywords: Raney gold; nanoporous gold; catalyst; thermal stability; Monte Carlo Raney gold; nanoporous gold; catalyst; thermal stability; Monte Carlo
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Tai, M.C.; Gentle, A.; De Silva, K.S.B.; Arnold, M.D.; Lingen, E.V.; Cortie, M.B. Thermal Stability of Nanoporous Raney Gold Catalyst. Metals 2015, 5, 1197-1211.

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