A series of Ti-modified mesoporous SiO 2 materials (SBA-15 and MCF) are prepared, characterised and used as catalysts in the selective epoxidation of a probe alkene (cyclohexene) using H 2 O 2 as an oxidising agent. Similarly, a series of mesoporous SiO 2 -supported monometallic and bimetallic DMAP-stabilized Au and Pd nanoparticles were prepared, characterised and used as catalysts in the production of H 2 O 2 from dilute H 2 (g) + O 2 (g) mixtures.The metallic nanoparticles were then supported on the Ti-modified mesoporous SiO 2 and these hybrid materials were characterised and their activities in the selective epoxidation of alkenes in the presence of H 2 (g) + O 2 (g) mixtures (where H 2 O 2 would be formed in situ) were studied. The bimetallic Au / Pd nanoparticles (which were most active in the production of H 2 O 2 from H 2 and O 2 )were not the most active or selective in the combined reaction. This was ascribed to the Pd component of the nanoparticles promoting hydrogenation of the probe alkene more rapidly than the formation of H 2 O 2 . The selectivity of Au nanoparticles in the presence of H 2 (g) + O 2 (g) was higher than that of the same catalysts in the presence of H 2 O 2 (aq).

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