Ruthenium-catalyzed oxidation of Np(IV) in nitric acid solutions

Oxidation of Np(IV) with nitric acid in the presence of Ru/SiO2 catalysts was studied by spectrophotometry. The catalytic oxidation of Np(IV) in nitric acid solutions occurs even in the presence of hydrazine. The mechanism of Ru-catalyzed oxidation of Np(IV) with nitric acid was suggested on the basis of the kinetic data. The effect of the Ru nanoparticle size on the activation energy of the catalytic oxidation of Np(IV) was revealed. It shows that the heterogeneous-catalytic reaction is structure-sensitive (positive size effect).