An environmentally friendly liquid-liquid heterogeneous oxidation of ethylbenzene catalyzed by NHPI, CoSPc and TBAB

Water was inducted as a solvent of catalysts in the oxidation of ethylbenzene catalyzed by a combined catalytic system consisting of NHPI and CoSPc, promoted by phase transfer catalyst TBAB. The present of water formed a liquid-liquid heterogeneous system, in which, the most favorable reaction conditions were optimized, Experimental results showed that the reaction conditions of controlling the volume ratio of water to ethylbenzene to be 3:1, the molar ratio of TBAB to ethylbenzen to be 1:40, n(NHPI):n(Ethylbenzene) = 1:10, n(NHPI):n(CoSPc) = 24:1, temperature = 110°C, stirring rate 350 rpm, O2 pressure 0.75 MPa, reaction time 0.5 h were the most favorable, under which the conversion of ethylbenzene reached 60.6%, the selectivity of acetophe-none and 1-phenylethanol reached 95.2% and 4.5%, respectively, and total products selectivity reached 99.7%. The conversion of ethylbenzene could not be improved by prolonging reaction time, otherwise, the selectivity of ace-tophenone decreased, empirical results indicated that the decomposition of NHPI took the blame of negative results in the improving of ethylbenzene conversion, the selectivity decrease of acetophenone was the consequence of it's over oxidation.