The Research On The Oxidation Of Toluene By Cobalt Acetate/Metalloporphyrins

The oxidation process of toluene is an extremely important reaction in chemical industry. The major products, benzaldehyde, benzyl alcohol and benzoic acid are widely used in pharmaceutical, dyestuff, perfumary, resin and textile fiber industries. At present, benzaldehyde and benzyl alcohol are mostly obtained by the chlorination of toluene followed by hydrolysis, a complex process discharging massive pollutant such as HCl gas and heavy metal salts, and benzoic acid is mostly produced by liquid-phase oxidation of toluene with air which suffers from corrosive solvents, bromides, or other initiators.In this thesis, the liquid-phase oxidation of toluene with oxygen was used in order to produce benzaldehyde, benzyl alcohol and benzoic acid. The influence of process conditions on the oxidation of toluene catalyzed by cobaltous acetate or cobaltous acetate /metalloporphyrin was systemic studied. The experimental results revealed that the conversion of toluene can be increased obviously when both cobalt acetate and metalloporphyrins were used under appropriate conditions. The contents of this thesis are presented as follows:1. Firstly, a new gas chromatography method with internal standard was proposed for the determination of benzaldehyde, benzyl alcohol and benzoic acid in order to meet with simultaneous quantitative analysis. We get the optimal analysis conditions. The method is simple,rapid and accurate.2. Secondly, the influences of process conditions on the oxidation of toluene with the catalyst cobaltous acetate , such as temperature, amount of catalyst, oxygen pressure were studied. Trace amount of benzaldehyde,benzyl alcohol and benzoic acid were added for the study of the effect of the conversion of toluene.3. Thirdly, different metalloporphyrins were studied. The catalytic activity of metalloporphyrins is in the order of T(p-Cl)PPMnCl > T(p-Cl)PPFeCl > T(p-Cl)PPCu > T(p-Cl)PPCo. Also catalyze by different metalloporphyrins with Co(OAc)₂ were studied. T(p-Cl)PPMnCl was selected as the optimal catalyst for co-catalyzation. The influences of process conditions on the oxidation of toluene with the catalysts system Co(OAc)₂/ T(p-Cl)PPMnCl, such as temperature, amount of catalyst, oxygen pressure. The experimental results revealed that the conversion of toluene can be increased obviously when both cobalt acetate and metalloporphyrins were used under the conditions of temperature lower than 180℃and the content of Co(OAc)₂ higher than 4000ppm.4. We compared the Co(OAc)₂/T(p-Cl)PPMnCl system with the system of Co(OAc)₂/MnCl₂ . Also compared the Co(OAc)₂/T(p-Cl)PPMnCl system with the system of Co(OAc)₂ alone on the point of the selectivity of production and the variety of the production﹐s content.5. Finally, on the basis of the well studied mechanism of cobaltous acetate and metalloporphyrins, A possible reaction mechanism was proposed on the basis of our study and references.