Decomposition of H₂O₂ on copper-containing ion-exchange resins of the vinylpyridine series

Abstract

By means of kinetic studies and EPR, it has been shown that, in the reaction of hydrogen peroxide decomposition in the presence of copper-containing anion-exchange resins of the vinylpyridine series AN-40, AN-25, and AN-251, the catalytic activity increases in a series of complexes of the following types: Cu(Py)₂ ²⁺<Cu(Py)₃ ²⁺<Cu(Py)₄ ²⁺. Increases in the degree of polymer cross-linking and increases in the content of copper complexes above 0.2 mg-ion/g lead to the appearance of steric hindrance to free diffusion of H₂O₂ molecules within the globules of resin, with a consequent decrease in specific catalytic activity of the ion-exchanger/metal complexes. It has been established by means of EPR and IR spectroscopy that in AN-25 and AN-251 CH₃ groups of the coordinated units are oxidized to carboxyl, with a consequent change in composition and structure of the Cu(II) complexes in the resins. Moreover, the copper ions are partly washed out from the resin into the reaction medium.