Aqueous phase (catalytic) wet air oxidation of ammonia: Thermodynamic considerations

•Thermodynamic calculations were performed on the (C)WAO of ammonia.•The evolution of the different equilibria was followed as a function of temperature.•Under the applied reaction conditions, ammonia is mostly present as NH3,l.•The calculation procedure developed here could be applied to other reaction systems.

The equilibrium concentrations in ammonia and ammonium ion in the liquid and gas phases could be calculated in the temperature range 25-250 °C, under typical operating conditions for the catalytic wet air oxidation of ammonia. A satisfactory agreement was obtained with the data collected upon blank experiments as well as in the presence of unreactive catalyst supports. Thermodynamic calculations appeared to be crucial to access a better comprehension of the reaction mixture composition under catalytic wet air oxidation reaction conditions, especially the ammonia partition and speciation among the different phases. New insights were gained in terms of ammonia reactivity.

Graphical abstractDownload high-res image (87KB)Download full-size image