Batch Reactor Data

Batch reactors are used primarily to determine rate law parameters for hotr geneous reactions. This determination is usually achieved by measuring cc centraiion as a function of time and then using either the differential, integr or nonlinear regression method of data analysis to determine the reacti order, a, and specific reaction rate constant, k. If some reaction parame other than concentration is monitored, such as pressure, the mole balance mi be rewritten in terms of the measured variable (e.g.. pressure as shown in t example in Solved Problems on the CD). 

When a reaction is irreversible, it is possible in many cases to determi the reaction order a and the specific rate constant by either nonlinear regrc sion or by numerically differentiating concern ration versus time data. This I ter method is most applicable when reaction conditions are such that the n is essentially a function of the concentration of only one reactant for examp if, for the decomposition reaction. 

However, by utilizing the method of excess, it is also possible to detf 

After determining a, the reaction is carried out in an excess of A, which the rate law is approximated as 

Once a and (3 are determined, can be calculated from the mea. iiire-ment of at known concentrations of A and B  

A rate equation characterizes the rate of reaction, and its form may either be suggested by theoretical considerations or simply be the result of an empirical curve-fitting procedure. In any case, the value of the constants of the equation can only be found by experiment predictive methods are inadequate at present. 

The determination of the rate equation is usually a two-step procedure first the concentration dependency is found at fixed temperature and then the temperature dependence of the rate constants is found, yielding the complete rate equation. 

Equipment by which empirical information is obtained can be divided into two types, the batch and flow reactors. The batch reactor is simply a container to hold the contents while they react. All that has to be determined is the extent of reaction at various times, and this can be followed in a number of ways, for example  

By following the change in some physical property of the fluid, such as the electrical conductivity or refractive index. 

By following the change in total pressure of a constant-volume system. 

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Chapter 3 Interpretation of Batch Reactor Data Reactor Movable bead... 

Figure 27.5 Either plot can be used to test and fit the M-M equation (Eq. 6) from batch reactor data.

Figure 29.3 Evaluation of the constants of the Monod equation from batch reactor data, method (b). ...

One measures Cj (t, T) for given Cjo and then finds a suitable method of analyzing these data to find a suitable rate expression that will fit them. For liquid solutions the typical method is to obtain isothermal batch-reactor data with different Cjo and continues to gather these data as a function of temperature to find a complete rate expression. For a simple irreversible reaction we expect that the rate should be describable as... 

One thus obtains a family of these isothermal lines from batch-reactor data for a given Cao for different temperatures, as shown in the graphs of Figure 2-19 for n = 1, 2, and f. 

At the same time, as a chemist I was disappointed at the lack of serious chemistry and kinetics in reaction engineering texts. AU beat A B o death without much mention that irreversible isomerization reactions are very uncommon and never very interesting. Levenspiel and its progeny do not handle the series reactions A B C or parallel reactions A B, A —y C sufficiently to show students that these are really the prototypes of aU multiple reaction systems. It is typical to introduce rates and kinetics in a reaction engineering course with a section on analysis of data in which log-log and Anlienius plots are emphasized with the only purpose being the determination of rate expressions for single reactions from batch reactor data. It is typically assumed that ary chemistry and most kinetics come from previous physical chemistry courses. 

Table Activity and Selectivity of Si02, 4% Mo03/Si02 and 5% 203/8102 Catalysts in Methane Partial Oxidation. Batch reactor data ...

For this study, mass transfer and surface diffusions coefficients were estimated for each species from single solute batch reactor data by utilizing the multicomponent rate equations for each solute. A numerical procedure was employed to solve the single solute rate equations, and this was coupled with a parameter estimation procedure to estimate the mass transfer and surface diffusion coefficients (20). The program uses the principal axis method of Brent (21) for finding the minimum of a function, and searches for parameter values of mass transfer and surface diffusion coefficients that will minimize the sum of the square of the difference between experimental and computed values of adsorption rates. The mass transfer and surface coefficients estimated for each solute are shown in Table 2. These estimated coefficients were tested with other single solute rate experiments with different initial concentrations and different amounts of adsorbent and were found to predict... 

A general method is presented for the development of chemical reaction rate equations from integral reactor and single-sample batch reactor data such as are obtained in process development studies. Following the scope of the method, three earlier foundation stones upon which the method rests, the method itself, and a simple illustration are presented. 

A similar approach holds for the interpretation of batch reactor data. Here, the spatial integration has to be replaced by a time integration of eq 4. A nice example of such an application is the catalyzed hydrodemetallization of Ni-porphyrins [57], a reaction of the type... 

DETERMINING A RATE EXPRESSION BY INTEGRAL ANALYSIS OF BATCH-REACTOR DATA 5.1... 

Scaie-Up of Liquid-Phase Batch Reactor Data to the Design ofaCSTR 129... 

From the batch reactor data below, determine whether first-order kinetics for lumping as two reactants A and B or second-order kinetics for lumping one reactant D best describes the system. Experimental conditions are such that one can neglect volume change. 

The parameters K and V , can readily be determined from batch reactor data by using the integral method of analysis, Dividing both sides of Equation (7-95) by tKJV and rearranging yields... 

Sec. 4.2 Scale-Up of Liquid-Phase Batch Reactor Data to the Design of a CSTR 135 Table E4-1.2. Stoichiometeic Table... 

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