Fundamentals of Chemical Reaction Engineering

Mark E. Davis, Robert J. Davis

• Publisher: Dover Publications
• Year: 2013
• ISBN:
  9780486291314
• Topic: Technologie et ingénierie
• Subtopic: Ingénierie de la chimie et de la biochimie

Appropriate for a one-semester undergraduate or first-year graduate course, this text introduces the quantitative treatment of chemical reaction engineering. It covers both homogeneous and heterogeneous reacting systems and examines chemical reaction engineering as well as chemical reactor engineering. The authors take a chemical approach, helping students develop an intuitive feeling for concepts, rather than an engineering approach, which tends to overlook the inner workings of systems and objects.
Each chapter contains numerous worked-out problems and real-world vignettes involving commercial applications. Topics include the basics of reaction kinetics and rate constants of elementary reactions, reactors for measuring reaction rates and the steady-state approximation, and heterogeneous catalysis. Additional subjects include the effects of transport limitations on rates of solid-catalyzed reactions, microkinetic analysis of catalytic reactions, nonideal flow in reactors, nonisothermal reactors, and reactors accomplishing heterogeneous reactions. Excellent illustrations complement the text, which concludes with three helpful appendixes.

CHAPTER 1

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The Basics of Reaction
Kinetics for Chemical
Reaction Engineering

1.1 | The Scope of Chemical Reaction Engineering

The subject of chemical reaction engineering initiated and evolved primarily to accomplish the task of describing how to choose, size, and determine the optimal operating conditions for a reactor whose purpose is to produce a given set of chemicals in a petrochemical application. However, the principles developed for chemical reactors can be applied to most if not all chemically reacting systems (e.g., atmospheric chemistry, metabolic processes in living organisms, etc.). In this text, the principles of chemical reaction engineering are presented in such rigor to make possible a comprehensive understanding of the subject. Mastery of these concepts will allow for generalizations to reacting systems independent of their origin and will furnish strategies for attacking such problems.

The two questions that must be answered for a chemically reacting system are: (1) what changes are expected to occur and (2) how fast will they occur? The initial task in approaching the description of a chemically reacting system is to understand the answer to the first question by elucidating the thermodynamics of the process. For example, dinitrogen (N₂) and dihydrogen (H₂) are reacted over an iron catalyst to produce ammonia (NH₃):

where ΔH_r is the enthalpy of the reaction (normally referred to as the heat of reaction). This reaction proceeds in an industrial ammonia synthesis reactor such that at the reactor exit approximately 50 percent of the dinitrogen is converted to ammonia. At first glance, one might expect to make dramatic improvements on the production of ammonia if, for example, a new catalyst (a substance that increases the rate of reaction without being consumed) could be developed. However, a quick inspection of the thermodynamics of this process reveals that significant enhancements in the production of ammonia are not possible unless the temperature and pressure of the reaction are altered. Thus, the constraints placed on a reacting system by thermodynamics should always be identified first.

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VIGNETTE 1.1.1

The initial success of a large-scale catalytic technology began in 1913 when the first industrial chemical reactor to synthesize ammonia from dinitrogen and dihydrogen began operation in Germany. Most of the ammonia manufactured today is used to produce nitrogen-rich fertilizers that have an enormous impact on meeting worldwide food demands. According to figures for U.S. agriculture, the 800,000 tons of dinitrogen converted to ammonia in the first Haber reactor (ammon...