Enhancing the catalytic activity of aluminum oxide for permanganate oxidation of phenols by N-doping and hydration

Aluminum oxide is an excellent catalyst in organic synthesis and petrochemistry but requires good crystallinity . This study used a simple low-temperature pyrolysis method to successfully synthesize an amorphous N-doped aluminum oxide (N-AO am , N-[Al(OH) 3 ] 0.47 [Al 2 O 3 ] 0.53 ) sample for catalytic KMnO 4 oxidation . N-AO am reduced the activation energy of the reaction and increased the TOC removal by forming oligomers . From a combined analysis of probe test, electrochemical measurement and DFT calculations, it was revealed that both N doping and hydration could lead to a decrease in LUMO energy of the MnO 4 − ···AO complex, facilitating the electron transfer process to enhance the oxidizing capacity of KMnO 4 . Finally, the universality of the KMnO 4 /N-AO am system for catalytic oxidation of various phenols was verified, with the establishment of a QSAR model by multiple linear regression and machine learning optimization. This study fundamentally reveals the key role of nitrogen doping on the basic catalyst alumina, helping the green and low-cost traditional oxidant KMnO 4 to be rebirthed. • N-doping enhances amorphous alumina performance over γ-alumina. • N-AO am lowered activation energy and increased TOC removal from 52 % to 77 %. • Hydration treatment promoted both reaction rate and TOC removal. • The complex lowered LUMO thus facilitating electron transfer . • N-AO am aqueous catalyst promoted removal of 18 phenols by KMnO 4 .