Preparation of Cu-MnOX/γ-Al2O3 by high gravity-assisted impregnation method for heterogeneous catalytic ozonation of nitrobenzene

This study considered the preparation of γ-Al2O3 supported Cu-Mn mixed oxides catalyst (Cu-MnOX/γ-Al2O3 (HGRPB)) using the high gravity-assisted impregnation method in a rotating packed bed. The catalyst had good dispersion of oxide, abundant surface oxygen vacancies, and high surface concentrations of Mn4+ and Cu0 species, which determined the excellent catalytic activity for nitrobenzene mineralization. The removal efficiency of total organic carbon by Cu-MnOX/γ-Al2O3 (HGRPB) prepared by the rotating packed bed for 45 min was almost 93.4%, which was 3 times that of single ozonation and was comparable to that of catalyst prepared by the stirred tank reactor for 6 h. Surface oxygen vacancy favored the adsorption and transformation of ozone into active species ·O2– and ·OH, which played the pivotal role in the mineralization of nitrobenzene. The lower pHPZC of Cu-MnOX/γ-Al2O3 (HGRPB), as well as the increased amount of oxygen vacancy, brought in the superior catalytic performance of Cu-MnOX/γ-Al2O3 (HGRPB) in weak acidic environment. This novel process encourages further development of high gravity towards industrial production of supported catalysts with superior catalytic ozonation performance.