Intrinsic Kinetics of Heterogeneous Reactions Involving Solids

Note that the enhancement factor E is relevant only for reaction occurring in the liquid film. For an instantaneous reaction, the expressions may or may not involve E, except that for liquid-film control, it is convenient, and for gas-film control, its use is not practicable (see problem 9-12(a)). The Hatta number Ha, on the other hand, is not relevant for the extremes of slow reaction (occurring in bulk liquid only) and instantaneous reaction. The two quantities are both involved in rate expressions for fast reactions (occurring in the liquid film only). 

3 INTRINSIC KINETICS OF HETEROGENEOUS REACTIONS INVOLVING SOLIDS 

The mechanisms, and hence theoretically derived rate laws, for noncatalytic heterogeneous reactions involving solids are even less well understood than those for surface-catalyzed reactions. This arises because the solid surface changes as the reaction proceeds, unlike catalytic surfaces which usually reach a steady-state behavior. The examples discussed here are illustrative. 

Gasification reactions of solids The reactions of solids with gas-phase reactants to form gaseous products are generally described in the same manner as are surface-catalyzed reactions. The reaction of carbon with water vapor is an example  

This reaction is important in such processes as the decoking of catalysts, the manufacture of activated carbon for adsorption, and the gasification of carbonaceous materials for production of hydrogen or fuel gas. 

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Intrinsic Kinetics of Heterogeneous Reactions Involving Solids 255... 

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