Page 19 - Introduction to chemical reaction engineering and kinetics

Chapter 1

Introduction

In this introductory chapter, we first consider what chemical kinetics and chemical re-
action engineering (CRE) are about, and how they are interrelated. We then introduce
some important aspects of kinetics and CRE, including the involvement of chemical sto-
ichiometry, thermodynamics and equilibrium, and various other rate processes. Since
the rate of reaction is of primary importance, we must pay attention to how it is defined,
measured, and represented, and to the parameters that affect it. We also introduce some
of the main considerations in reactor design, and parameters affecting reactor perfor-
mance. These considerations lead to a plan of treatment for the following chapters.
Of the two themes in this book, kinetics and CRE, the latter is the main objective,
and we consider kinetics primarily as it contributes to, and is a part of, CRE.

1.1 NATURE AND SCOPE OF CHEMICAL KINETICS
Chemical kinetics is concerned with the rates of chemical reactions, that is, with the
quantitative description of how fast chemical reactions occur, and the factors affecting
these rates. The chemist uses kinetics as a tool to understand fundamental aspects of
reaction pathways, a subject that continues to evolve with ongoing research. The ap-
plied chemist uses this understanding to devise new and/or better ways of achieving
desired chemical reactions. This may involve improving the yield of desired products
or developing a better catalyst. The chemical engineer uses kinetics for reactor design
in chemical reaction or process engineering.
A legitimate objective of chemical kinetics is to enable us to predict beforehand the
rate at which given chemical substances react, and to control the rate in some desirable
fashion; alternatively, it is to enable us to “tailor” chemical reactions so as to produce
substances with desirable chemical characteristics in a controllable manner, including
choice of an appropriate catalyst. Quantum mechanical calculations theoretically pro-
vide the tools for such predictions. Even with today’s powerful computers, however, we
are far from being in a position to do this in general, and we must study experimentally
each reacting system of interest in order to obtain a quantitative kinetics description of
it.

1.2 NATURE AND SCOPE OF CHEMICAL REACTION ENGINEERING

Chemical reaction engineering (CRE) is concerned with the rational design and/or
analysis of performance of chemical reactors. What is a chemical reactor, and what
does its rational design involve? A chemical reactor is a device in which change in com-

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