Catalytic wet air oxidation of ethylene glycol in a trickle-bed reactor

Wastewater from many sources must be treated to remove contaminants before it can be discharged to the environment. Biological treatment is the primary method used for the removal of organic compounds, although it is not specifically designed for this purpose. As concern increases regarding the discharge of organic compounds, more effective methods such as catalytic wet air oxidation are being explored. In this study, the oxidation of ethylene glycol, (a major component in deicing fluid for aircraft) was studied, both as a model compound and in its own right.; In this research, a trickle-bed reactor was designed and constructed to study catalytic wet air oxidation. Platinum supported on a hydrophobic material was selected for the catalyst. At 110{dollar}spcirc{dollar}C, ethylene glycol was oxidized completely to carbon dioxide and water. At slightly lower temperatures, the oxidation products were glycolic acid and carbon dioxide as well as a number of other byproducts. A major challenge of the work was minimizing mass transfer effects and catalyst deactivation. A gradual drop in ethylene glycol conversion was attributed to irreversible poisoning of the catalyst by trace metals, and competitive adsorption of byproducts with ethylene glycol. The rate of reaction was found to have a half order dependence on ethylene glycol concentration. Competitive adsorption between ethylene glycol and glycolic acid was also accounted for in the rate of reaction model. Sodium hydroxide was found to increase the conversion to glycolic acid and decrease the conversion to carbon dioxide.