Specific reaction-rate constant determination

In each of the following reactions determine the specific reaction rate constant for each of the other species in the reaction. Assume that in each case has a value of 25 with the appropriate combination of units of mol, dm, g cat, mid s. (a) For the reaction... 

This chapter focuses attention on reactors that are operated isotherraally. We begin by studying a liquid-phase batch reactor to determine the specific reaction rate constant needed for the design of a CSTR. After iilustrating the design of a CSTR from batch reaction rate data, we carry out the design of a tubular reactor for a gas-phase pyrolysis reaction. This is followed by a discussion of pressure drop in packed-bed reactors, equilibrium conversion, and finally, the principles of unsteady operation and semibatch reactors. 

To determine the reaction order by the integral method, we guess the reaction order and integrate the differential equation used to model the batch system. If the order we assume is correct, the appropriate plot (detemtined from this integration) of the concentration-time data should be linear. The integral method is used most often when the reaction order is known and it is desired to evaluate the specific reaction rate constants at different temperatures to determine the activation energy. 

It is desired to design a CSTR to produce 200 million pounds of ethylene glycol year by hydrolyzing ethylene oxide. However, before the design can be carried c it is necessary to perform and analyze a batch reactor experiment to determine specific reaction rate constant, k. Because the reaction will be carried out isoth mally, the specific reaction rate will need to be determined only at the reaction tc perature of the CSTR. At high temperatures there is a. significant by-prod formation, while at temperatures below 40 C the reaction does not proceed at a s nificant rate consequently, a temperature of 55°C has been chosen. Because water is usually present in excess, its concentration may be considered constant d ing the course of the reaction. Tlie reaction is first-order in ethylene oxide. 

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). 

Part (1) Detemitie the reaction order with respect to triphenyl methyl chloride. Part (2) In a separate set of experiments, the reaction order wrt methanol was found to be first order. Determine the specific reaction rate constant. 

The problem is not simply solved by conventional procedures, for low concentrations of methanol are difficult to measure, and determinations of loss of trityl chloride (85) or formation of hydrogen chloride do not provide directly the change in methanol concentration. Further, Swain believes that some base must be present to remove the hydrogen chloride as it is formed otherwise, the methanolysis is reversible. This circumstance presents additional difficulties for measurement of specific reaction rate constants. 

Mislow and co-workers (1963) carried out at least three kinetic runs for each specific reaction rate constant to be determined for the compounds 115, 116 and 117 and their undeuteriated analog, a total of fourteen in all, and the number of observations per run varied from 29 to 44. Using the criterion of Collins and Lietzke, referred to earlier. 

From kinetic experiments the rates of loss of the two glycols were determined, and from product analyses the specific reaction rate constants were further subdivided into the rates of appearance of those... 

Note that we must determine the specific reaction rate constant ks as well as the heat transfer coefiicient h independent of our scaling effort. We have previously discussed methods for determining ks and h. 

Rast method analy chem The melting-point depression method often used for the determination of the molecular weight of organic compounds. rast, meth-ad ) rate constant physchem Numerical constant in a rate-of-reaction equation for example, = feCaACbBCcC, where Cp, C, and are reactant concentrations, k is the rate constant (specific reaction rate constant), and a. b, and care empirical constants. rat, kan-stant ... 

The use of a laboratory batch reactor to determine the specific reaction rate constant, k, for the liquid-phase reaction EO form ethylene glycol. 

---