The importance of diffusion in a catalyst are increased by ____________________?

Related Mcqs:

1. Effectiveness factor E. of a catalyst pellet is defined as, E = (actual rate within pore of the catalyst)/(rate if not snowed by pore diffusion), Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus) ___________________?

   A. tan hT/T
   B. tan T/T
   C. tan hT/tan T
   D. None of these

2. A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A → B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?

   A. Inner catalyst core of radius R/8 does not participate in reaction
   B. Inner catalyst core of radius R/2 does not participate in reaction
   C. Inner catalyst core of radius 7R/8 does not participate in reaction
   D. Effectiveness factor for a zero order reaction cannot be 7/8 as it must always be 1

3. Following isothermal kinetic data are obtained in a basket type of mixed flow reactor for a porous catalyst. Determine the role of pore diffusion and external mass transfer processes ?

   A. Strong pore diffusion control and mass transfer not controlling
   B. Both pore diffusion and mass transfer not controlling
   C. Both pore diffusion and mass transfer controlling
   D. Mass transfer controlling

4. Bulk diffusion in catalyst pore _______________ with increase in pressure?

   A. Increases
   B. Decreases
   C. Remains unchanged
   D. Increases exponentially

5. If Thiele modulus is ________________, then the pore diffusion resistance in a catalyst may be considered as negligible?

   A. 0
   B. ∞
   C. < 0.5
   D. > 0.5

6. A catalyst is said to be a negative catalyst, if it ___________________?

   A. Retards the rate of reaction
   B. Reduces the value of equilibrium constant
   C. Does not initiate the reaction
   D. All A., B. and C.

7. For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to ____________________?

   A. 0
   B. 1
   C. 0.1
   D. 0.5

8. A Catalyst ____________________?

   A. Increases the equilibrium concentration of the product
   B. Changes the equilibrium constant of the reaction
   C. Shortens the time to reach the equilibrium
   D. None of these

9. Knudsen diffusion is directly proportional to _____________________?

   A. T
   B. √T
   C. 1/√T
   D. T2

10. When the reaction is dominated by intraparticle diffusion, the apparent order of reaction (nD) as measured is related to the true order (n) as ________________?

    A. nD = (n + 1)/2
    B. nD = n/2
    C. nD = n + 1
    D. None of these