Which of the following factors control the deactivation of a porous catalyst pellet?

Related Mcqs:

1. A first order reaction A → B occurs in an isothermal porous catalyst pellet of spherical shape. If the concentration of A at the centre of the pellet is much less than at the external surface, the process is limited by__________________?

   A. Diffusion within the pellet
   B. Reaction
   C. External mass transfer
   D. None of the above

2. 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

3. 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

4. Effectiveness factor of a catalyst pellet is a measure of the _________________ resistance?

   A. Pore diffusion
   B. Gas film
   C. Chemical reaction
   D. None of these

5. Effective diffusivity (DE) in a catalyst pellet is related to molecular diffusivity (DN) and Knudsen diffusivity (DK) as_________________?

   A. DE = DM + DK
   B. 1/DE = 1/DN + DK
   C. DE = DM . DE
   D. DE = DN/DE

6. Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates is not used to derive BET equation ?

   A. Langmuir’s assumption applies to every adsorbed layer
   B. There is no dynamic equilibrium between successive layer
   C. The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer
   (except the first one) is involved in each of the evaporation process
   D. None of these

7. 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

8. B.E.T. method can be used to determine the ___________________ of a porous catalyst?

   A. Solid density
   B. Pore volume
   C. Surface area
   D. All A., B. and C.

9. For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the____________________?

   A. Catalyst size is reduced or the catalyst diffusivity is reduced
   B. Catalyst size is reduced or the catalyst diffusivity is increased
   C. Catalyst size is increased or the catalyst diffusivity is reduced
   D. Catalyst size is increased or the catalyst diffusivity is increased

10. 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