Page 194 - Introduction to chemical reaction engineering and kinetics

Chapter 8

Catalysis and Catalytic

Reactions

Many reactions proceed much faster in the presence of a substance that is not a prod-
uct (or reactant) in the usual sense. The substance is called a catalyst, and the process
whereby the rate is increased is catalysis. It is difficult to exaggerate the importance
of catalysis, since most life processes and industrial processes would not practically be
possible without it.
Some industrially important catalytic reactions (with their catalysts) which are the
bases for such large-scale operations as the production of sulfuric acid, agricultural fer-
tilizers, plastics, and fuels are:

so, + ;02 s so, (promoted V,O, catalyst)

N, + 3H, $2NH, (promoted Fe catalyst)
CsH,, * CsH, + H, (K&O,, Fe oxide catalyst)
CO + 2H, jt CH,OH (Cu, Zn oxide catalyst)

ROOH (organic hydroperoxide) + C,H, +
C,H,O + ROH (soluble MO organometallic catalyst)
CH,CHCH2 + C,H, + cumene (solution or solid acid catalyst)

In this chapter, we first consider the general concepts of catalysis and the intrinsic
kinetics, including forms of rate laws, for several classes of catalytic reactions (Sections
8.1 to 8.4). We then treat the influence of mass and heat transport on the kinetics of
catalytic reactions taking place in porous catalyst particles (Section 8.5). Finally, we
provide an introduction to aspects of catalyst deactivation and regeneration (Section
8.6). The bibliography in Appendix B gives references for further reading in this large
and important field.

8.1 CATALYSIS AND CATALYSTS

8.1.1 Nature and Concept

The following points set out more clearly the qualitative nature and concept of catalysis
and catalysts:
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