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1.	The activity of a catalyst pellet is defined as the ratio of ___(a) Rate of adsorption of reactants to the catalyst surface to the rate at which the catalytic pellet converts the reactant(b) Rate at which the catalytic pellet converts the reactant to the rate of adsorption of reactants to the catalyst surface(c) Rate at which the catalytic pellet converts the reactant to the rate of reaction with a fresh pellet(d) The rate of reaction with a fresh pellet to the rate at which the catalytic pellet converts the reactantThis question was addressed to me by my college professor while I was bunking the class.My question is based upon Mechanisms of Catalyst Deactivation topic in portion Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» Correct option is (c) Rate at which the catalytic pellet CONVERTS the reactant to the rate of reaction with a fresh pellet For explanation I WOULD say: ACTIVITY is a measure of the catalyst performance. It is DEFINED as the ratio of rate at which the catalytic pellet converts the reactant to the rate of reaction with a fresh catalyst pellet.

2.	If the rate of deactivation is given by –\(\frac{da}{dt}\) = 0.0064 day^-1, the expression relating activity and time is ___(a) a = 0.0064t(b) a = 1-0.0064t(c) a = t(d) a = 0.0064-tThe question was posed to me at a job interview.My question is based upon Mechanisms of Catalyst Deactivation topic in division Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» The CORRECT OPTION is (b) a = 1-0.0064t The EXPLANATION is: –\(\FRAC{da}{dt}\)= 0.0064 –\(\int_1^a\)da = 0.0064\(\int_0^t\)dt Integrating, a = 1-0.0064t

3.	The slope of the curve of ln\((ln\frac{C_A}{C_{A∞}})\) and t for batch solid – fluid independent deactivation system is ___(a) ln(lnkd)(b) ln(kd)(c) kd(d) -kdI have been asked this question by my college director while I was bunking the class.I'd like to ask this question from Mechanisms of Catalyst Deactivation in chapter Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» Right answer is (d) -kd Explanation: ln\((ln\FRAC{C_A}{C_{A∞}})\) = ln \(\frac{Wk’}{Vk_d}\) – kdt. The slope of the CURVE is -kd and the INTERCEPT is ln\(\frac{Wk’}{Vk_d}. \)

4.	The catalyst deactivation caused by deposition on surface and pores of catalyst is called ____(a) Adsorption(b) Regeneration(c) Fouling(d) DesorptionI had been asked this question by my school teacher while I was bunking the class.My question is taken from Mechanisms of Catalyst Deactivation topic in division Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» The CORRECT option is (c) Fouling For explanation I WOULD SAY: Fouling is CAUSED by the blockage of pores on the catalyst. The life and the efficiency of the catalyst is reduced by fouling.

5.	The rate expression for independent deactivation for batch solids is ____(a) ln\((ln\frac{C_A}{C_{A∞}})\) = ln \(\frac{Wk’}{Vk_d}\) – kdt(b) ln \(\frac{C_A}{C_{A∞}}\)= ln \(\frac{Wk’}{Vk_d}\) – kdt(c) lnln \(\frac{C_A}{C_{A∞}}\)= ln \(\frac{Wk’}{Vk_d}\)(d) lnln \(\frac{C_A}{C_{A∞}}\)=\(\frac{Wk’}{Vk_d}\) – kdtI had been asked this question during an online interview.This interesting question is from Mechanisms of Catalyst Deactivation in section Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» Right option is (a) ln\((ln\frac{C_A}{C_{A∞}})\) = ln \(\frac{Wk’}{Vk_d}\) – kdt To explain I would SAY: For BATCH solids – fluid, –\(\frac{-dC_A}{dt} = \frac{W}{V}\)K’CAA and –\(\frac{da}{dt}\) = kda^d. Integrating and combining the equations, ln\((ln\frac{C_A}{C_{A∞}})\) = ln \(\frac{Wk’}{Vk_d}\) – kdt.

6.	State true or false.In parallel deactivation, the reactant produces a side product which deposits on the catalytic surface and deactivates it.(a) In parallel deactivation, the reactant produces a side product which deposits on the catalytic surface and deactivates it.(b) True(c) FalseThis question was addressed to me in homework.Asked question is from Mechanisms of Catalyst Deactivation topic in portion Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» Right answer is (a) In parallel deactivation, the reactant PRODUCES a side product which deposits on the CATALYTIC SURFACE and deactivates it. To explain I would SAY: A parallel deactivation is the one in which reactant A produces the product R and the poison P. A→R + P↓

7.	Which of the following reactor arrangements causes fast deactivation?(a) Mixed flow for fluid(b) Plug flow for fluid(c) Fluidised bed reactor(d) Batch for fluid and solidI have been asked this question by my school teacher while I was bunking the class.The query is from Mechanisms of Catalyst Deactivation topic in chapter Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» Correct answer is (c) Fluidised BED reactor Best EXPLANATION: Fluidisation causes high CATALYTIC deactivation. The catalytic particles are well MIXED by the REACTANT fluid.

8.	The activity of a catalyst at a time t = 0 is ____(a) Negative(b) Zero(c) Unity(d) ∞This question was addressed to me by my college director while I was bunking the class.I'd like to ask this question from Mechanisms of Catalyst Deactivation topic in chapter Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» The CORRECT option is (c) Unity The best explanation: When the reaction has not YET started to occur, the catalyst surface is not poisoned. The entire surface on the catalyst is available to promote the reaction. At a time t=0, the activity is the highest and equal to 1. The value of ‘a’ lies between 0 and 1 as ‘a’ is the ratio of rate of reaction achieved by the catalyst at any GIVEN time to the maximum rate that can be achieved by a fresh catalyst.

9.	Which of the following represents series type deactivation model? (Where R is the product and P is the poison)(a) A → R → P↓(b) A → P↓(c) A→R + P↓(d) A → R, A → PI had been asked this question during an interview.My question is from Mechanisms of Catalyst Deactivation topic in chapter Suspended Solid Reactors, Catalyst Deactivation, Diffusion and Reaction of Chemical Reaction Engineering
Answer» Correct answer is (a) A → R → P↓ Explanation: The series deactivation is the MECHANISM in which the PRODUCT MAY decompose to produce the poison or further react to produce the poison. The poison DEPOSITS on the catalyst and causes deactivation.