Site isolation for light hydrocarbons oxidation

From consideration of several examples of catalytic oxide systems, it appea rs that the mild oxidation of light alkanes to oxygenates is controlled by the local properties of the surface of oxides which favour the isolation of the active cation or of a controlled number of active sites. This appears to be quite general on massic mixed oxides as well as on supported oxides. Two examples are given for n-butane oxidation to maleic anhydride on the VP O catalyst and for ethane oxidation to acetic acid on the VPMoO/TiO2 cataly st. This conclusion was reached by using several physicochemical techniques which are complementary and may distinguish the surface and the bulk prope rties of the catalytic oxides. As a consequence, the improvement of the per formance of a catalytic oxide system and the discovery of new generation of catalysts will stem from the modification at short distance of the local e nvironment of the active site.