摘要
用TG-DTA-DSC热分析仪研究了Cu-Co-Fe系催化剂在程序升温还原过程中的中间态变化及其动力学。发现催化剂的还原是分阶段进行的,第一段主要是Cu,Co组分的还原,第二段为Fe组分的还原。由于组分间的交互作用,铁组分的还原容易进行。Co组分的还原经历了Co_3O_4→CoO→Co的过程;Cu组分是CuO先还原成Cu_2O,然后还原为Cu。用Coats-Redfern法对实验数据作动力学处理,其结果与用Broido法处理的相一致。表明此法可用于多相还原过程,得到还原动力学的有关参数。
The intermediates and kinetics of reduction of Cu-Co-Fe catalysts in the process of TPR have been studied by TG-DTA-DSC thermal analyzer. It is found that the process of reduction of catalysts falls into two stages. In the first stage, the reduction of Cu, Co oxides occupies a dominant position, and the reduction of a-Fe2O3 takes place in the second stage. Because of the interaction between CuCo and Fe components, the reduction of a-Fe2O3 is carried out easily. Both Cu2O and CoO as intermediates are verified in TPR process. The kinetic parameters of reduction obtained by Coats-Redfern method agree very well with those by Broido method. The apparent activation energy E of reduction is linearly proportional to the pre-exponential factor Ig A. Very large E and reaction order n of some samples in second stage resulted from the complexity of the reduction process, such as adsorption, desorption and the formation of intermediates.
