Role of Mass Transport in Gas-Carbon Reactions

Heterogeneous reaction rates involving a porous solid and a gas may be controlled by one or more of three major steps  

Mass transport of reacting gas and product or products across a relatively stagnant gas film between the exterior surface of the solid and the main gas stream. 

Mass transport of the reacting gas from the exterior surface to an active site beneath the surface and mass transport of the products in the opposite direction. 

Chemisorption of reactant, wholly or in part a rearrangement of chemisorbed species on the surface to a desorbable product(s) and desorption of product or products from the surface. 

It is imperative that anyone attempting to understand the kinetics of the gas-carbon reactions also understand the role which the above steps (separately or in combination) can play in affecting values determined for orders of reaction, activation energies, and reaction rates. In the field of 

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