Research Of Liquid-phase Selective Oxidation Of Toluene To Benzaldehyde

Benzaldehyde is an important chemical material in industry. Benzaldehyde can be widely used in several fields such as spice, dye, medicine and so on. The traditional process of chlorination hydrolysis of toluene to benzaldehyde is gradually replaced by the process of liquid-phase oxidation of toluene to benzaldehyde by air which can be more profitable and environment-friendly and has advantages of mild reaction conditions and easy operation.This paper deals with the liquid-phase catalytic oxidation of toluene to benzaldehyde by air in high pressure stirred reactor over organic salt of Co/Mn. The result shows that with the increase of time, the conversion of toluene is increased but the selectivity and concentration of benzaldehyde are increased firstly and then decreased. The concentration of benzaldehyde is highest at2h and the system can be stable after3h. With the rise of temperature, the conversion of toluene is increased, while the selectivity of benzaldehyde is decreased. The concentration of benzaldehyde reaches a maximum value at160℃. The result obtained shows that the conversion of toluene and concentration of benzaldehyde are highest at the air flow rate of1L/min and with the catalyst content of150ppm, the reaction is conducted completely as well as be maintained higher yield of benzaldehyde. When revolving speed is faster than400rpm, the experimental data is hardly altered and the concentration of benzaldehyde is higher at500rpm. The reaction is accelerated effectively with benzaldehyde of2mL as promoter but the selectivity and yield of benzaldehyde are reduced. At the base of reasonable analysis of the toluene oxidation process, a reaction network and kinetic model are built. The reaction order, pre-exponential factor and activation energy are calculated according to experimental kinetic data.