Richard D. Oldroyd

Preparation, characterisation and performance of encapsulated copper-ruthenium bimetallic catalysts derived from molecular cluster carbonyl precursors

High-performance, bimetallic nanoparticle catalysts (M1+M2) were obtained by gentle thermolysis of their precursor metal-cluster carbonylates physisorbed inside the mesoporous channels of silica (the hexagons in the figure). The Cu–Ru catalyst anchored on silica is stable in use and has been tested in the catalytic hydrogenation of hex-1-ene, diphenylacetylene, phenylacetylene, stilbene, cis-cyclooctene, and D-limonene.

Metallocene-derived, isolated MoVI active centres on mesoporous silica for the catalytic dehydrogenation of methanol

Isolated MoVI active sites have been grafted onto the inner surfaces of MCM-41 mesoporous silica via a molybdocene dichloride precursor, to generate a catalyst which has been tested for the oxidative dehydrogenation of methanol. Mo K-edge X-ray absorption spectroscopy shows that, after calcination, at low Mo loadings (ca. 1 mol% with respect to SiO2), isolated MoO4 species are generated on the surface, whereas at higher loadings (ca. 4 mol%) there is some evidence for the formation of polymeric oxo-molybdenum species. Catalysis tests show that lower Mo loadings on the MCM-41 silica lead to higher selectivity for the production of formaldehyde, in contrast to the results of previous studies of isolated Mo species on pure silica, which report that methyl formate is the major product.

Superior performance of a chiral catalyst confined within mesoporous silica

A chiral catalyst from the ligand 1,1′-bis(diphenylphosphino)ferrocene (dppf) anchored to the inner walls of the mesoporous support MCM-41 and co-ordinated to PdII has been shown to exhibit a degree of regioselectivity and enantiomeric excess, in the allylic amination of cinnamyl acetate, which is far superior to that of its homogeneous counterpart or that of a surface-bound analogue attached to a non-porous silica.

Creation, characterisation and performance of vanadyl active sites in microporous and mesoporous silica-based catalysts for the selective oxidation of hydrocarbons

We here describe how to design vanadium-centred active sites at the inner surfaces of both well defined microporous and well defined mesoporous siliceous hosts. Each type of vanadia–silica catalyst has been extensively characterised (in regard to surface area, pore size and hydrophobicity) and X-ray absorption spectroscopy establishes the active site for these conversions to be a vanadyl group. These centres are catalytically active under mild conditions for both the epoxidation of a typical alkene and the selective oxidation of a typical alkane. Placing methyl groups in the vicinity of this active site significantly enhances the catalytic performance towards epoxidation.

ENGINEERING AN ATOMICALLY WELL DEFINED ACTIVE SITE FOR THE CATALYTIC EPOXIDATION OF ALKENES

The improvement effected by replacing one of the three O–Si groups to which a TiIV ion is anchored (to a mesoporous silica support) by a O–Ge group is described, as is the detailed structure retrieved by in situ X-ray absorption spectroscopy of the created active site.