True Liquid Crystal Templating of Nanoparticle-doped Mesoporous Silica

Abstract

Using true liquid crystal templating (TLCT), a one-pot method for preparing mesoporous silicas containing metal nanoparticles is available. The method leads to well-defined systems with possible applications is selective catalysis. Using this approach, a range of metal-doped variants of hexagonal silicas (general MCM-41 family) are prepared and show surface areas >1000 m2 g–1 and pore diameters of ca 30 Å. Specifically, palladium doped-MCM-41-like silicas are prepared and are shown to be active in the selective oxidation of crotyl alcohol and the activity of the system has been investigated as a function of both metal loading and the pore length – the latter affecting mass transport and therefore rate of conversion. Templating on Pluronic P123 leads to doped SBA-15-like materials, but in contrast to the findings with low-concentration templating as commonly reported, TLCT leads to materials with surface areas of about 400 m2 g–1, which is accounted for by the absence of micropores. Catalytic results from these SBA-15 materials will also be presented.