Nitrogen doping carbon deriving from ionic liquid anchoring Ru coated on P-zeolite as high activity and stability catalyst for the catalytic wet air oxidation of highly concentrated ammonia

The treatment of the highly concentrated ammonia-nitrogen wastewater major produced in the coal chemical industry is a challenging problem. Herein, a novel catalyst with high activity and hydrothermal stability was designed for the catalytic wet air oxidation (CWAO) of the highly concentrated ammonia. In the designed catalytic system, P-zeolite was treated with sodium hydroxide to form defects for enhancing the adsorption of active metals. And the ionic liquid was employed as an N-doped carbon coating on treated P-zeolite to protect the ruthenium nanoparticles from leaching and improve its hydrothermal stability. The simultaneous introduction of ionic liquid and Ru precursor was beneficial to the dispersion of Ru on P-zeolite. The resulting catalyst Ru/Pzeolite(NaOH)@NC overcomes the poor hydrothermal stability of zeolite and exhibits excellent catalytic performance during the CWAO of highly concentrated ammonia. The catalyst of 1%Ru/P-zeolite(NaOH)@NC offers 100% conversion under 2 MPa at 200 degrees C in 4 h for 2000 ppm ammonia. No substantial deactivation was observed after five cycles. This study provides an effective strategy for the application of N-doped carbon coating on zeolite in CWAO systems.