Liquid-phase oxidation of toluene by air was carried out by using Co(acac)2 as catalyst in a 1 L stirred tank reactor.The product distributions of toluene oxidation and the effect of Co concentrations on the oxidation reaction of toluene were investigated.The life of Co(acac)2 catalyst was studied under different reaction temperatures and Co concentrations.The results showed that toluene oxidation was multiple reactions in parallel and series steps.A phenomenon of "catalyst- inhibitor" transition was found for Co(acac)2 catalyst like other Co salt catalyst.The appropriate Co(acac)2 dosage was 0.0044%(mass).Co(acac)2 catalyst life changed with reaction temperature and had the longest value at 165℃.Co(acac)2 catalyst might lose its activity easily at a lower reaction temperature (<165℃).The conversion of toluene and yield of benzoic acid could reach 19% and 80% respectively at reaction time 4 hours

reaction temperature 165℃ and Co concentration 0.0044%.Co(acac)2 catalyst has less catalyst dosage and longer lifetime than other Co salt catalysts like cobalt acetate

cobalt naphthenate

etc.

which could slow down the scaling of cobalt oxalate during reaction.Therefore Co(acac)2 catalyst has a good application prospect as catalyst in liquid-phase oxidation of toluene.