Bernard Paweł, Stelmachowski Paweł, Broś Paweł, Makowski Wacław, Kotarba Andrzej
Jagiellonian University, Faculty of Chemistry, ul. Gronostajowa 2, 30-387 Krakow, Poland.
J Chem Educ. 2021 Mar 9;98(3):935-940. doi: 10.1021/acs.jchemed.0c01101. Epub 2021 Jan 15.
Heterogeneous catalysis plays an important role in many chemical reactions, especially those applied in industrial processes, and therefore, its theoretical foundations are introduced not only to students majoring in chemical engineering or catalysis but also as part of general chemistry courses. The consideration of catalytic activity of various solids and mechanisms of catalytic reactions requires the introduction of the concept of an active site, which together with the catalyst specific surface area are discussed as key parameters controlling the reaction rate. There are many known demonstrations of heterogeneous catalysis phenomena that can be performed live in a lecture hall, but all of them focus only on the general idea of catalytic processes and are not suitable for quantitative analysis. Therefore, herein we present a simple demonstration of the influence of the specific surface area of a catalyst on the rate of a catalytic reaction. This demonstration is based on a model reaction of hydrogen peroxide decomposition catalyzed by cobalt spinel (CoO) calcined at various temperatures. The differences in reaction rates can be monitored visually, and the obtained data can be used directly for a simple kinetic analysis, including comparison of numerical values of the reaction rate constants.
多相催化在许多化学反应中起着重要作用，尤其是那些应用于工业过程中的反应。因此，其理论基础不仅会介绍给化学工程或催化专业的学生，也会作为普通化学课程的一部分进行讲授。考虑各种固体的催化活性和催化反应的机理需要引入活性位点的概念，活性位点与催化剂比表面积一起被视为控制反应速率的关键参数进行讨论。有许多已知的多相催化现象演示可以在讲堂上现场进行，但所有这些演示都只关注催化过程的一般概念，并不适合进行定量分析。因此，在此我们展示一个简单的演示，说明催化剂比表面积对催化反应速率的影响。该演示基于在不同温度下煅烧的钴尖晶石（CoO）催化过氧化氢分解的模型反应。反应速率的差异可以通过肉眼观察到，所获得的数据可以直接用于简单的动力学分析，包括比较反应速率常数的数值。
