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[vistaVSxp]

1)      Diffusion limitations with different sized catalysts

 

a.       A first order reaction A→P takes place in a slab shaped catalyst. The effectiveness factor due to diffusion limitations in the pores is 0.8. Assuming no other reaction rate limitations, if the slab length is four times larger how much larger is the total rate of reaction?

 

b.      A first order reaction A→P takes place in a spherical catalyst pellet. The effectiveness factor due to diffusion limitations in the pores is 0.8. Assuming no other reaction rate limitations, if the pellet diameter is four times larger how much larger is the total rate of reaction?

 

c.       Explain what this means in each case and the implications for increased particle size in this situation. Compare your answers for the slab and the sphere. 

[thorium90]

This question is clearly about the Thiele modulus. The following should be a good explanation.

 

http://books.google....ylinder&f=false