The role played by carbon deposition products in partial oxidation of ethylene glycol to glyoxal on a copper catalyst

The scanning electron microscopy and thermographic and elemental analysis methods were used to show that two different types of carbon deposition products were formed on the surface of copper depending on the content of oxygen in the reaction mixture, namely, graphite-like films and oxycarbonaceous fibers. The interaction of ethylene glycol with the surface of copper catalysts treated in reaction media of various compositions was studied by the method of programmed-temperature reactions. The formation of graphite-like structures was observed on nonoxidized copper surface regions and resulted in blocking surface active centers. Carbon deposition products of the second type, carbonaceous fibers, were formed under the action of oxygen-containing reaction media. Growth of fibers was accompanied by the emergence of high-dispersity copper crystallites, which intensified the synthesis of glyoxal.