Experimental Methods for Finding Rates

Any type of reactor with known contacting pattern may be used to explore the kinetics of catalytic reactions. Since only one fluid phase is present in these reactions, the rates can be found as with homogeneous reactions. The only special precaution to observe is to make sure that the performance equation used is dimensionally correct and that its terms are carefully and precisely defined. 

The experimental strategy in studying catalytic kinetics usually involves measuring the extent of conversion of gas passing in steady flow through a batch of solids. Any flow pattern can be used, as long as the pattern selected is known if it is not known then the kinetics cannot be found. A batch reactor can also be used. In turn we discuss the following experimental devices  

Differential (flow) reactor Integral (plug flow) reactor Mixed flow reactor Batch reactor for both gas and solid 

Differential Reactor. We have a differential flow reactor when we choose to consider the rate to be constant at all points within the reactor. Since rates are concentration-dependent this assumption is usually reasonable only for small conversions or for shallow small reactors. But this is not necessarily so, e.g., for slow reactions where the reactor can be large, or for zero-order kinetics where the composition change can be large. 

For each run in a differential reactor the plug flow performance equation becomes 

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