氧氯化催化剂的吸附和反应性能及其活性位置——Ⅱ.氧氯化催化剂的反应性能与活性位置

脉冲反应结果表明,氧氯化催化剂本身与乙烯的反应,和真正的氧氯化反应不仅产物相同,而且活化能相近,初始比活性都随Cu含量而增加。但在进行多次脉冲反应时,前者活性衰减直至失活,后者却有上长并趋平稳的趋势。Cu含量较低时,催化剂只能使HCl气氛下的乙烯转化为DCE,而不能与乙烯单独反应。表明前者可能确实是后者必经的第一步反应,活性位置是一些互相邻近、具有较多配位氯的Cu~(2+)离子。

The Reaction Behavior and Active Sites of Oxychlorination Catalyst

The results of pulse reaction show that the reaction between ethylene and oxy- chlorination catalyst, and the genuine oxychlorination reaction are similar in that both convert ethylene to dichloroethane (DCE), and both have nearly the same activation energy with the initial specific activity increasing with increase in Cu content. However on repeatedly conducting pulse reaction, the activity in the former case declines until complete deactivation; while in the latter case, the activity in creases until a steady level is reached. Catalysts of low Cu content (such as 1％Cu) are unable to react alone with othylene; it can only convert ethylene to DCE under an atmosphere of HCl. It thus shows that the former is really a necessary first step in oxychlorination reaction. The active sites are closely neighboring cupric ions having a comparatively large number of coordinated C1.