Elements of Heterogeneous Catalysis

In 1835, Berzelius coined the term catalysis to describe the influence of certain substances on the nature of diverse reactions, the substances themselves apparently being unchanged by the reaction. He imbued these materials with a catalytic force capable of awakening the potential 

Catalysts that decrease reaction rates are usually referred to as inhibitors. They often act by interfering with the free-radical processes involved in chain reactions, and the mechanism usually differs from that involved in accelerating a reaction. The most familiar example of the use of inhibitors has historically been the addition of additives such as tetraethyllead or methyl terf-butyl ether to gasoline to improve its antiknock properties. 

A catalyst cannot change the ultimate equilibrium point set by thermodynamics, but it can affect the rate at which this point is approached. More importantly, it can facilitate the approach to equilibrium with respect to a desired reaction while not influencing the rates of other less desirable reactions. In optimizing yields of desired products, chemical engineers are very concerned with the selectivity or specificity of a catalyst for commercial applications, selectivity is often more important than activity per se. 

Introduction to Chemical Engineering Kinetics and Reactor Design, Second Edition. Charles G. Hill, Jr. and Thatcher W. Root. 2014 John Wiley Sons, Inc. Published 2014 by John Wiley Sons, Inc. 

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