Langmuir Isotherm for Simultaneous Adsorption of Two Gases

The total fraction of the surface covered by components A and B is then given by 

In general, when i substances are being simultaneously adsorbed, we get 

This step, however, assumes that the value of is the same for both components A and B. 

Although the adsorption of gaseous mixtures is, in practice, much more important than the adsorption of a single pure gas in catalysis, the knowledge of the subject is very incomplete and the information available is not always reliable. 

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