Catalytic Ozonation of Quinoline Utilizing Manganese-Based Catalyst with Abundant Oxygen Vacancies

S-MnO2, Cl-MnO2, and Ac-MnO2 samples were prepared by redox method with the oxidant (KMnO4) and the reducing agent precursors [MnSO4, MnCl2 and Mn(Ac)(2)]. This work studied the influence of the precursors on the catalytic performance. Ac-MnO2 was aminated and doped with graphene to obtain the modified manganese-based catalyst MnO2-NH2-GO. XRD, Raman, FTIR, XPS, NH3-TPD, CV (cyclic voltammetry) were used to characterize the catalyst. The average oxidation state (AOS) of Mn element was also calculated. The results of the catalytic ozonation quinoline degradation experiment shown that the four catalysts was ranked as follows: S-MnO2 < Cl-MnO2 < Ac-MnO2 < MnO2-NH2-GO, which was related to the catalyst crystal structure, oxygen vacancy (O-vac)content, AOS, and catalyst surface acidity and other factors. The effects of CO32-, HCO3-, SO42-, and Cl- on the catalytic reaction were investigated, the effects of different anions vary greatly. By adding tertiary butyl alcohol (tBA) and benzoquinone (pBQ) radical scavengers, it was confirmed that OH and O-2(-) coexisted, but O-2(-) contributed much more to oxidation than OH. Graphic Abstract

Automated summary

Different manganese-based catalysts were prepared by redox method using different precursors, and their catalytic performances were studied. After amination and graphene doping, a modified catalyst MnO2-NH2-GO showed the best performance, which was related to catalyst's physical and chemical properties.