A. Lessens its selectivity
B. May be useful for suppressing undesirable side reactions
C. Is added in small quantity during the catalyst manufacture itself
D. All A., B. and C.
Related Mcqs:
- 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 - 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. - 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 - 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. - 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 - 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 - 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 - Carbon particles accumulated on the catalyst used in the gas oil cracking lies in the category of _____________________ poison?
A. Deposited
B. Chemisorbed
C. Selectivity
D. Stability - 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 - Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene: 95 kmole / hr, water vapour: 97.5 k mole / hr and diethyl ether: 2.5 kmole/hr. The reactions occuring can be represented by: C2H5OH → C2H4 + H2O 2C2H5OH → C2H5 – O – C2H5 + H2O The percent conversion of ethanol in the reactor is________________?
A. 100
B. 97.5
C. 95
D. 2.5
