Elements of
Chemical Reaction Engineering
6th Edition



Home

Essentials of
Chemical Reaction Engineering
Second Edition

  Select  Chapter  >>     TOC     Preface     1     2     3     4     5     6     7     8     9     10     11     12     13     14     15     16     17     18     Appendices  
›

By Chapter Hide

  • Objectives
  • Living Example Problems
  • Extra Help
  • - Summary Notes
  • - LearnChemE Screencasts
  • - FAQs
  • - Interactive Computer Modules
  • Additional Material
  • Self Test
  • i>Clicker Questions
  • Professional Reference Shelf

By Concept Hide

  • Interactive Modules
  • -Web Modules
  • -Interactive Computer Games
  • Living Example Problems

U of M Hide

  • Asynchronous Learning
  • ChE 344
  • ChE 528

Chapter 15: Diffusion and Reaction in Porous Catalysts

Additional Homework Problems

CDP15-LC

The hydrogenation of aromatics in a napthenic lube oil distillate takes place in a trickle bed reactor. The bed is 1 m in diameter and 6 m deep. The solubility of hydrogen in the oil is 0.0068 mol/dm 3middotatm. The concentration of aromatics in the feed is 0.07 mol/ dm 3. The superficial liquid flow rate is 8 kg/m 2middots, while the hydrogen flow rate is 0.2 kg/m 2middots. The reaction is first-order in hydrogen and in aromatics on the

1/8-in. catalyst pellet. The true specific reaction rate is 2 x 10 -5 m 6 /kmolmiddotkgmiddots. Nitrogen enters with the hydrogen at a rate of 0.05 kg/m 2middots. The reaction occurs at 100°C and 50 atm.

(a) Make a plot of conversion of aromatics as a function of bed depth.
(b) Calculate the percent resistance of each transport step.
(c) How would the exit conversion change if the gas flow rate were reduced by a factor of 4?
(d) How could the conversion be increased?

Additional information:

Effective liquid diffusivity of H 2 in oil: 8 x 10 -9 m>2 /s
Effective liquid diffusivity of aromatics in oil: 6 x 10 -11 m 2 /s
Viscosity of oil: 3.0 cP
Bed porosity: 0.35
Pressure gradient for flow of 0.25 kg gas/m 2middots: 30 kPa/m
Density of oil: 900 kg/m 3
Pellet Density: 1500 kg/m 3
Tortuosity: 3.8
Porosity: 0.5
Construction: 0.8

[2nd Ed. P12-8]