Thermal Stability of Nanoporous Raney Gold Catalyst

Metals

Matthew C. Tai²  Angus Gentle²  Kaludewa Sujeewa B. de Silva²  Matthew D. Arnold²  Elma van der Lingen¹  Michael B. Cortie²  Eva Pellicer³ 

[1] Department of Engineering and Technology Management, University of Pretoria, Lynnwood Road, Hatfield, Pretoria 0002, South Africa; E-Mail:;Institute for Nanoscale Technology, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia; E-Mails:Institute for Nanoscale Technology, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia;

关键词: Raney gold;    nanoporous gold;    catalyst;    thermal stability;    Monte Carlo;   

DOI  :  10.3390/met5031197

来源: mdpi

【 摘 要 】

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”.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.