Efficient Selective Oxidation of Aromatic Alkanes by Double Cobalt Active Sites over Oxygen Vacancy-rich Mesoporous Co 3 O 4

The development of efficient catalyst for selective oxidation of hydrocarbon to functional compounds remains a challenge. Herein, mesoporous Co O (mCo O -350) showed excellent catalytic activity for selective oxidation of aromatic-alkanes, especially for oxidation of ethylbenzene with a conversion of 42 % and selectivity of 90 % for acetophenone at 120 °C. Notably, mCo O presented a unique catalytic path of direct oxidation of aromatic-alkanes to aromatic ketones rather than the conventional stepwise oxidation to alcohols and then to ketones. Density functional theory calculations revealed that oxygen vacancies in mCo O activate around Co atoms, causing electronic state change from Co →Co . Co has great attraction to ethylbenzene, and weak interaction with O , which provide insufficient O for gradual oxidation of phenylethanol to acetophenone. Combined with high energy barrier for forming phenylethanol, the direct oxidation path from ethylbenzene to acetophenone is kinetically favorable on mCo O , sharply contrasted to non-selective oxidation of ethylbenzene on commercial Co O .