Treatment of Ammonia by Catalytic Wet Oxidation Process Over Platinum‐Rhodium Bimetallic Catalyst in a Trickle-Bed Reactor: Effect of pH

This work adopted aqueous solutions of ammonia for use in catalytic liquid-phase reduction in a trickle-bed reactor with a platinum‐rhodium bimetallic catalyst, prepared by the co-precipitation of chloroplatinic acid (H₂PtCl₆) and rhodium nitrate [Rh(NO₃)₃]. The experimental results demonstrated that a minimal amount of ammonia was removed from the solution by wet oxidation in the absence of any catalyst, while approximately 97.0% of the ammonia was removed by wet oxidation over the platinum‐rhodium bimetallic catalyst at 230°C with an oxygen partial pressure of 2.0 MPa. The oxidation of ammonia has been studied as a function of pH, and the main reaction products were determined. A synergistic effect is manifest in the platinum‐rhodium bimetallic structure, in which the material has the greatest capacity to reduce ammonia. The reaction pathway linked the oxidizing ammonia to nitric oxide, nitrogen, and water.