The effects of material properties on the activity of sol-gel entrapped perruthenate under supercritical conditions

Silica gels organically modified and doped with the ruthenium species tetra-n-propylammonium perruthenate (TPAP) are leach-proof, selective catalysts for the aerobic oxidation of alcohols to carbonyl compounds with dioxygen at low pressure in compressed carbon dioxide. The catalytic sol-gels are recyclable and the correlation between the reactivity of the materials and their surface polarity and textural properties suggests valuable information on the chemical behaviour of sol-gel entrapped silica catalysts in oxidation catalysis which is of relevant interest considering the importance of heterogeneous oxidative dehydrogenation of alcohols in fine chemistry. An explanation of the structure-activity relationship is proposed to provide guidelines for the further development of efficient solid oxidation catalysts for conversions in supercritical carbon dioxide.