Page 62 - Principles of Catalyst Development
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CATALYTIC MATERIALS
What They Are
It has been said that everything is a catalyst for something. Although
profound, the statement is not very useful unless materials are organized
into groups with common properties, explained with theories or models,
and systematized into patterns from which new catalysts may be predicted.
In this chapter we examine common types of catalytic materials, current
theories underlining their mode of action, and activity patterns useful in
design. Much of this is brief by necessity, but the interested reader will find
sufficient references for further study. For the casual reader, this chapter
illustrates the complex background in catalysis and testifies to the current
attempts to lift catalysis from an "art" to a "science."
4.1. TYPES OF CATALYTIC MATERIALS
Catalytic materials fall into well-defined categories. Although we use
broader classifications than those given in Chapter 1, the motivation is the
same-to group according to common types of activity and to explain the
catalytic behavior on the basis of common properties.
Table 4.1 is a list of catalytic materials with examples. The state of
each catalyst is a consequence of process demands, e.g., for high activity,
or degree of interaction with other components. Classification by electrical
conductivity, as metals, semiconductors, and insulators, remains a satisfac-
tory method in treating the theoretical background and behavior patterns
of these widely differing materials.
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