温度和氧浓度对PX氧化的影响

根据不同温度、氧浓度下实测的PX液相催化氧化各中间组分浓度 时间关系,采用双曲型的动力学模型拟合实验数据,得到了各步反应活化能数据和速率常数与氧浓度的关系式。结果说明,PT酸氧化为4 CBA这一步的活化能最大,是整个连串反应过程的速率控制步骤;反应有一个氧浓度门槛值,在此值以上,反应速率不再明显增大,在此值以下,反应速率随氧浓度增大而增大。工业尾氧体积分数一般在4%～5%,相应的反应速率在最大速率的90%左右。

The effect of temperature and oxygen concentration on p-xylene oxidation

Experiments of p xylene liquid phase oxidation at different temperatures of 185～197 ℃and oxygen volume fraction of 3%～37% are carried out to investigate the temperature and oxygen concentration effect on p xylene oxidation. A hyperbolic kinetics model is employed to fit the data. The obtained activation energy of different reaction steps ranges from 54 to 93 kJ/mol, among them the activation energy of PT acid to 4 CBA step is the highest (92.8 kJ/mol). The rate constants obtained and oxygen concentration can be well represented by a hyperbolic relationship. The result shows that the rate of reaction will not increase visibly when the oxygen volume fraction exceeds 7%. In the range of 4%～5% of industrial reactor, the reaction rate is about 90% of the highest reaction rate.