Catalytic wet oxidation of quinoline over Ru/C catalyst

In the present work, catalytic wet air oxidation of the model nitrogenous organic compound quinoline was studied in a slurry reactor over 5% Ru/C catalyst between 423 and 598 K temperature, 0.34 and 2.07 MPa oxygen (O2) partial pressure, and 0.025 and 0.1 kg m−3 catalyst loading. This catalyst was very effective, thereby suggesting its utility for the oxidative destruction of wastewaters polluted by nitrogenous organic compounds. From analysis of the mass transfer effects, it was found that the investigated reaction belonged to the kinetics-controlled reaction regime. Kinetic data on TOC destruction were fitted to a two-step first-order power law model: the first step was fast, whereas the second step was slow. The values of activation energy for the two steps were 29 and 93 kJ mol−1. Among the hyperbolic models tested, the model with a slow surface reaction between chemisorbed TOC and dissociatively adsorbed O2 was most appropriate. The fate of the nitrogen atom in the feed solution and its conversion to nitrite and nitrate ions, ammonia and nicotinic acid was established. Finally, it was corroborated that the reaction was fast when pyrex liner was used inside the reactor because free radicals were not destroyed by the reactor wall.