Unit 40. Gas-Solid Reactions

This website provides learning and teaching tools for a first course on kinetics and reaction engineering. In the preceding parts of the course, the reacting fluid was always treated as if it was homogeneous, and only ideal reactor types were considered. The knowledge gained to this point is sufficient for reaction engineering for many commercial processes. Nonetheless, there are situations where the reactor does not conform to one of the ideal types and/or the rates are affected by the kinetics of physical processes in addition to the chemical reaction rate. Part IV of the course surveys a few such situations. It does not provide an in-depth analysis of any of them, but the information provided should serve as a good foundation for further study.

This, final section of the course, considers situations where the kinetics are affected by factors other than the rate of the chemical reaction. This topic was introduced as part of the discussion on performing kinetics experiments in Part II of the course, specifically in Unit 12. The perspective and objective there was to ensure that these other factors were sufficiently small in magnitude so that they could be ignored. In Section A of this part of the course, specifically in Unit 37, it was noted that when two phases are present in a reactor, concentration and temperature gradients may exist near the interface between phases, and the design equations must properly account for those gradients. Section B of Part IV introduces a few ways that this can be accomplished. Once again, a limited, introductory presentation is offered with comprehensive treatment left for a second, more advanced course on kinetics and reaction engineering.

Reactions between a gas and a solid involve the same issues of interfacial gradients as those encountered in heterogeneous catalysis. There is one significant additional issue with gas-solid reactions. Specifically, the solid is being consumed over time. Unit 40 provides an overview of models that can be used to simultaneously capture the effect of interfacial gradients and that of a changing solid size and pore structure.

Learning Resources

• Archive (.zip) - Contains all learning resources listed below for this unit
• Documents to Read:
  • Unit 40 Informational Reading (.pdf)
  • Example 40.1 (.pdf)
• Videos to Watch (please right-click and save, then play back locally on your computer):
  • Unit 40 Informational Video (.mov)
  • Example 40.1 Video (.mov)
• Reference Files:
  • Unit 40 Definitions, Nomenclature and Equations (.pdf)

Teaching Resources

• Archive (.zip) - Contains all teaching resources listed below for this unit
• Sample Class
  • Online Pre-class Quiz (.pdf file)
  • Redacted slides to make available to students before class
    • Keynote 09
    • PowerPoint
  • Other files to make available to students before class
    • Worksheet for Activity 40.1
  • Class Lesson Plan (.pdf)
  • Complete slides to make available to students after class
    • Keynote 09
    • PowerPoint

Practice Problems

1. to be added.