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用静态重量法研究了丙烯还原α-钼酸铋和α-钼酸铋(经丙烯的预还原)在氧中的再氧化这两个过程的动力学。在350～450℃的温度区间内,生成丙烯醛反应的表现活化能为15.8Kcal/mole;对丙烯的反应级数从高温下的1变到低温下的0.3。在相同的温度区间,氧对催化剂再氧化的表观活化能出现转折,高温区为12.0Kcal/mole,低温区为33.2Kcal/mole;对氧的反应级数近于1。 根据我们的实验结果,对α-钼酸铋与氧气和丙烯混合体系的反应动力学行为做了如下解释:高温下(>380℃),反应的控速步是丙烯对催化剂的还原;低温下,反应的控速步为氧对催化剂的再氧化。
The kinetics of the two processes of propylene reduction of bismuth α-molybdate and bismuth α-molybdate (prereduced by propylene) reoxidation in oxygen was studied by static gravimetric method. In the temperature range of 350 ~ 450 ℃, the activation energy of the acrolein reaction was 15.8Kcal / mole; the reaction order of propylene changed from 1 at high temperature to 0.3 at low temperature. In the same temperature range, the apparent activation energy of oxygen reoxidation of catalyst turned into a turning point, the high temperature region was 12.0Kcal / mole, the low temperature region was 33.2Kcal / mole; the reaction order to oxygen was nearly 1. According to our experimental results, the reaction kinetics of α-molybdate with oxygen and propylene is explained as follows: At high temperature (> 380 ℃), the rate-controlling step of the reaction is the reduction of propylene on the catalyst; at low temperature , The reaction rate-controlled step of oxygen re-oxidation of the catalyst.