Chapter 10: Catalysis and Catalytic Reactors

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		The differential method of analysis can also be used to determine the order of decay for experiments carried out in either a CSTR or a plug-flow reactor. To illustrate this method, we consider a stirred contained solids reactor (SCSR), in which we measure the concentrations as a function of time. We assume the decay rate law to be of the form

			(CD10-16)

		The design equation for the SCSR is the same as that for a CSTR. Consequently, for the n th-order irreversible reaction



		the activity at any time t is given by

			(CD10-17)

		Taking the log and differentiating with respect to time, we get

			(CD10-18)

		Combining Equations (10-136) and (10-137) yields

			(CD10-19)

		Substituting Equation (10-141) for a and taking the ln of both sides gives us

(CD10-20)


		We see that the reaction order can be found from a plot on log-log paper similar to that shown in Figure CD10-4. The data to construct this plot could be arranged as shown in Table CD10-2. By plotting the last column as a function of the reciprocal of the second column on log-log paper the decay order q can be obtained.



		Figure CD10-4 Differential method for determining order of decay