Dibutyl phthalate (DBP), a plasticizer, has a potential market of 12 million lbm/yr (AICHh...

Dibutyl phthalate (DBP), a plasticizer, has a potential market of 12 million lbm/yr (AICHhE Student Contest Problem) and is to be produced by reaction of n-butanol with monobutyl phthalate (MBP). The reaction follows an elementary rate law and is catalyzed by H2SO4 (Figure P4-6n). A stream containing MBP and butanol is to be mixed with the H2SO4 catalyst immediately before the stream enters the reactor. The concentration of MBP in the stream entering the reactor is 0.2 lb mol/ft3, and the molar feed rate of butanol is five times that of MBP. The specific reaction rate at 100 °F is 1.2 ft3/lbmol h. There is a 1000-gallon CSTR and associated peripheral equipment available for use on this project for 30 days a year (operating 24 h/day).

(a) Determine the exit conversion in the available 1000-gallon reactor if you were to produce 33% of the share (i.e., 4 million lbm/yr) of the predicted market.

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(b) How might you increase the conversion for the same FA()? For example, what conversion would be achieved if a second 1000-gal CSTR were placed either in series or in parallel with the CSTR? [X2 = 0.55 (series)]

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(c) For the same temperature as part (a), what CSTR volume would be necessary to achieve a conversion of 85% for a molar feed rate of MBP of I lb mol/min?

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(d) If possible, calculate the tubular reactor volume necessary to achieve 85% conversion, when the reactor is oblong rather than cylindrical, with a major-to-minor axis ratio of 1.3 : 1.0. There are no radial gradients in either concentration or velocity. If it is not possible to calculate VPRP explain.

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(e) How would your results for parts (a) and (b) change if the temperature were raised to 150 °F where k is now 5.0 ft3/lb mol • h but the reaction is reversible with Kc = 0.3?

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(f) Keeping in mind the times given in Table 4–1 for filling, and other operations, how many 1000-gallon reactors operated in the batch mode would be necessary to meet the required production of 4 million pounds in a 30- day period? Estimate the cost of the reactors in the system. Note: Present in the feed stream may be some trace impurities, which you may lump as hexanol. The activation energy is believed to be somewhere around 25 kcal/mol. Hint: Plot the number of reactors as a function of conversion. (An Ans.: 5 reactors)

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(g) What generalizations can you make about what you learned in this problem that would apply to other problems?

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(h) Write a question that requires critical thinking and then explain why your question requires critical thinking. [Hint: See Preface, Section B.2]