Phenol Catalytic Wet Air Oxidation Over Ru Nanoparticles Formed in Hypercrosslinked Polystyrene

Catalytic wet air oxidation (CWAO) of phenols is an important process of environmental catalysis, allowing one to reach nearly complete oxidation of phenols to non-hazardous compounds. Here we report syntheses of nanocatalysts based on Ru-containing nanoparticles (NPs) formed in the pores of hypercrosslinked polystyrene (HPS) and their catalytic properties in the phenol CWAO under mild conditions. The Ru species were incorporated in HPS using wet impregnation of ruthenium(IV) hydroxychloride in a complex solvent followed by the NaOH and H₂O₂ treatment. The catalysts containing from 0.5 to 2.8 wt% of Ru were studied by X-ray fluorescence analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, and liquid nitrogen physisorption methods. The NP sizes were controlled by the pores of HPS. The two types of Ru species: Ru(IV) and Ru(IV) × nH₂O, constituted the NP composition. The effects of the phenol and catalyst initial concentrations and temperature were investigated in the phenol CWAO. Removal of 97 % of phenol was observed for the most active catalyst containing 2.8 wt% of Ru.