由DTG曲线确定反应级数的新方法

利用动态热重曲线求固相反应动力学参数的方法很多,如微分差分法,微分法和积分法等,有关数据处理方法中,反应级数n的获得尤为重要,因为有的需要预先知道反应级数或通过尝试才能求得反应级数;如Coats-redfern法,最大速率法等。有的方法虽可由实验直接确定反应级数,但精度低。前文曾采用逐步逼进法对Coats-redfern法中最佳n值的获得进行了讨论。本文根据DTG-TG曲线的特点,探求一种简便获得反应级数n的方法,通过研究CaC_2O_4·H_2O的分解反应,对该方法的可靠性进行论证。

A NEW METHOD FOR DETERMINATION OF REACTION ORDER BY DERIVATIVE THERMOGRAVIMETRY

A new method for determination of reaction order n by DTG curve is presented in this paper. The reliability of the method is illustrated by the investigation of the decomposition process of CaC_2O_4·H_2O. The result shows that the peak area of DTG Curve corresponds to the change of sample weight. The reaction order n may be determined by the following equation: 1-x_m=1/e (n=1); 1-x_m=n~(1/(1-n)) (n≠1)Where x_m represents the fraction reacted at maximum rate of the reaction, x_m can be calculated by the ratio of sample changed at the top of DTG peak ...