Liquid-phase oxidation of ethylene glycol on a Pt/C catalyst. I. Deactivation and regeneration of the catalyst.

Ethylene glycol was oxidized to glycolic acid in an alkaline solution over a Pt/C catalyst, and data were collected at 40°C and ambient pressure in a liquid-full reactor. During a run, strong catalyst deactivation took place, but could be partly reversed by temporarily stopping the reaction or treating the catalyst with formalin. The catalyst activity could also be restored (though not completely) by oxidizing the deactivated catalyst with oxygen, followed by reduction with hydrogen. The deactivation of the catalyst is ascribed to the formation of some oxidized species (unknown) of platinum and/or to catalyst poisoning. The reactivation of the catalyst during the stopping period or on treatment with formalin is considered to be due to a reduction reaction between the oxidized species of Pt and ethylene glycol or formalin. The decay of catalyst activity is well described by a first-order deactivation process.