非均相钌催化高铁酸盐氧化降解苯酚

In this study, we developed ruthenium-based (Ru-based) catalysts with ZSM-5, TiO₂ and CeO₂ as supports, and examined their performance for catalyzing ferrate (Fe(Ⅵ)) oxidation of caffeine or phenol. With the introduction of Ru/ZSM-5, Ru/TiO₂, and Ru/CeO₂, the pseudo-first-order reaction rate constants (k_obs, min^-1) of Fe(Ⅵ) oxidation of phenol increase linearly with the dosage of each catalyst. The enhancement from each catalyst depends more on the dispersion of ruthenium nanoparticles on the supports than the loading of ruthenium. Hence, we observed comparable catalytic performance for these three catalysts with Ru/ZSM-5 having the highest dispersion, but the lowest loading of ruthenium nanoparticles. Ruthenium nanoparticles significantly increased the removal of phenol at pH 5.0—9.0, while its catalytic performance was greatly affected by pH. Ru intermediate with higher oxidation state, Ru^Ⅶ, was proved to be the major active species in ruthenium catalyzed Fe(Ⅵ) oxidation. To investigate the stability of catalysts, we used Ru/CeO₂, Ru/TiO₂ and Ru/ZSM-5 for ten consecutive times under same reaction conditions. It was found that the stability of Ru/CeO₂ and Ru/TiO₂ are better than Ru/ZSM-5, which would favor their application in pilot or engineering practice. The depressed performance of Ru/ZSM-5 may be mainly associated with masking active sites by the deposited ferric hydroxide.