Page 310 - Elements of Chemical Reaction Engineering 3rd Edition

Multiple Reactions 6

The breakfast of champions is not cereal, it’s your
opposition.
Nick Seitz

Seldom is the reaction of interest the only one that occurs in a chemical reactor.
Typically, multiple reactions will occur, some desired and some undesired. One
of the key factors in the economic success of a chemical plant is the minimization
of undesired side reactions that occur along with the desired reaction.
In this chapter we discuss reactor selection and general mole balances for
multiple reactions. There are three basic types of multiple reactions: series,
parallel, and independent. In parallel reactions (also called competing reac-
tions) the reactant is consumed by two different reaction pathways to form dif-
ferent products:

Parallel reactions A A’
dc
dc

An example of an industrially significant parallel reaction is the oxidation of
ethylene to ethylene oxide while avoiding complete combustion to carbon
dioxide and ate-

Senous chemistry CH,=CH2 + 02 /2c02 + 2H20
/O\
CH2-CH2
In series reactions, also called consecutive reactions, the reactant forms
an intermediate product, which reacts further to form another product:

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