Elements of
Chemical Reaction Engineering
6th Edition



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Essentials of
Chemical Reaction Engineering
Second Edition

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Chapter 8: Multiple Reactions

Additional Homework Problems

CDP8-KB

    The oxidation of formaldehyde to formic acid was studied over a vanadium-titanium oxide catalyst [Ind. Eng. Chem. Res. 28, 387 (1989).] Initially, we consider the occurrence of only the following two reactions:  
       
   

IMAGE 06eq8.gif

 
       
    These reactions occur simultaneously in the gas phase. As a first approximation, assume each reaction to be elementary. The following specific reaction rates are with respect to HCHO  
       
   

IMAGE 06eq10.gif

 
       
    (a) For an entering volumetric flow rate of 100 dm3 / min at 5 atm and 140°C, plot the molar flow rates as a function of PFR volume. The feed is 66.7% HCHO and 33.3% O2 .
(b) Repeat part (a) for a CSTR using space time as your variable rather than reactor volume. 		 
       
   

IMAGE 06eq11.gif

 
       
    The space time can be varied by varying the flow rate.  
    (c) For a CSTR space time of 10 minutes, vary the ratio of O 2 to HCHO in the feed. Plot the yield of HCOOH and the selectivity of HCOOH to HCOOCH2 as a function of IMAGE 06eq12.gif  
   

(d) Assume that the relative values of k 1 and k 2 can be adjusted by varying temperature and catalyst composition. Vary the rations k 1 /k 2 and simultaneously to learn their combined effects on selectivity and HCCOH yield. Write a paragraph describing your findings.

[2nd ed. P9-13]