Experimental Determination of Reaction Velocity

With this classification of the activity-determining factors in mind, it will be possible to evaluate the general abilities and limitations of some of the standard experimental methods namely, the static system and the flow-type catalytic reactors used for activity determinations. 

It is customary to contain catalyst and reactant in a closed vessel and to interpret the functional relationship of the composition of the gas phase versus time. The interpretation of the data is particularly simple 

The elimination of diffusion effects or their treatment as an independent correction factor will be described in Section IV, and it will therefore be sufficient to use the expression (4) as a starting point. For those reactions involving pressure change, this expression must be translatable in terms of a variation of gas pressure with time. For this purpose the reaction to be expected needs to be known, for then dn/dt will be expressible 

Clearly, in order to arrive at a value for k, it will be necessary to have some knowledge of the kinetics which determines the function / (p) and the associated integral. 

for the determination of absolute intrinsic activity constants, the kinetics must be capable of formal description as demonstrated above, the static system measurement is often used to derive just such information concerning the kinetic form of the reactions by considering fc , on the other hand, to be a constant. 

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