Chapter 15: Diffusion and Reaction in Porous Catalysts

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Example CD12-7: Effect of Catalyst Weight on Particle Size--Rapid Reaction

    We again consider the effect of doubling particle size while keeping all other variables the same. Case 1,d p1 = d p1 ; case 2, d p>I2 = 2d p1.  
       
    Solution

Using Equation (CD12-77) and taking the ratio of case 1 to case 2 gives 		 
       
   

image 12eq240.gif

(CDE12-8.1)
       
    Recalling from previous examples that  
       
   

image 12eq241.gif

 
       
    then  
       
   

image 12eq242.gif

(CDE12-8.2)
    or  
       
   

image 12eq243.gif

(CDE12-8.3)
       
       
    In this case we see that doubling the particle diameter decreases the catalyst weight by 89% while maintaining the same conversion. However, for a fast reaction, a significant decrease in effectiveness factor could offset this advantage.