Effect of Pt nanoparticle size on the specific catalytic activity of Pt/SiO₂ and Pt/TiO₂ in the total oxidation of methane and n-butane

The dependence of the specific catalytic activity (A (sp) ) of the catalysts Pt/SiO2 and Pt/TiO2 in the total oxidation of CH4 and n-C4H10 on the Pt nanoparticle size (in the range from 1 to 4 nm) was studied. The specific catalytic activity increases with an increase in the platinum nanoparticle size, indicating that the total oxidation is a structure-sensitive reaction. The structure sensitivity depends on the size of an oxidized molecule: it increases sharply on going from CH4 to n-C4H10. The support also exerts a considerable effect on the A (sp) value: in the oxidation of both CH4 and C4H10 the specific catalytic activity for the catalysts Pt/TiO2 is 3-4 times that for Pt/SiO2.