'Rocks-in-forest' catalyst supports
A new type of catalyst support has been designed by Yi Tang, Hualong Xu and co-workers at Fudan University in Shanghai, China. They embedded silver-based microparticle catalysts in silicon nanowire arrays. The Si nanowire arrays not only provide a barrier to the possibility of agglomeration of the metal particles, but also provide an open environment with exposure of the active species for catalytic reactions.
Catalyst supports need to maintain a high dispersion of active components and facilitate the diffusion of reactants to active sites. Silver based catalysts have been extensively researched as oxidation catalysts and are used in industrial processes. However, many silver catalysts possess poor catalytic activity at low temperatures and a strong agglomeration tendency of the silver species at high temperatures.
The motivation behind the work was to fabricate catalysts that possess small metal particle sizes, whilst maintaining sufficient stability for strong-exothermic reactions. This was 'hard to realise by using traditional catalyst supports. Thus we came up with a novel silver-based composite catalyst with silicon nanowire arrays as the support', says Tang.
The novel silicon nanowire array support is more stable and open than porous materials when applied to strongly-exothermic and diffusion-limited reactions. Therefore, 'this composite catalyst is promising for future applications in oxidation of high alcohols and similar reactions', said Tang.
Original publication: Hualong Xu, Yi Tang et al., Chem. Commun., 2008.
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