Chapter 10 Self Test

Catalyst Decay in a Batch Reactor

The elementary irreversible gas phase catalytic reaction

is carried out isothermically in a batch reactor. The catalyst deactivation follows a first order decay law and is independent of the concentrations of both A and B.




Additional information:

            CA0 = 1 mol/dm3

                V0 = 1 dm3

               W = 1 kg

            kd = 0.1 min-1 at 300 K                 Ed/R = 2,000 K

            k1 =0.2 dm3/(kg cat · min) at 300 K Ea/R = 500 K

 

Hint 1 Write the algorithm and determine a general expression for catalyst activity as a function of time.

Hint 2 Make a qualitative sketch of catalyst activity as a function of time. Does a(t) ever equal zero for a first order decay law?

Hint 3 Write out the general algorithm and derive an expression for conversion as a function of time, the reactor parameters and the catalyst arameters.

Fill in the following algorithm

                                                                    Mole balance

                                                                       Rate Law

                                                                     Decay Law

                                                                    Stoichiometry

                                                                       Combine

Solve

                                                                     1) Separate

                                                                     2) Integrate

                                         

Hint 4 Calculate the conversion and catalyst activity in the reactor after 10 minutes at 300 K.

Full Solution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 1. Algorithm and a(t)

            Batch–

                  Mole Balance                  

                  Rate Law                         

                  Decay Law

            First-order decay law

 

 

 

 

 

   

Back to Hints

Back to Problem

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 2

Sketch a(t)

 

 

 

a(t) never equals zero for a first-order decay law

Back to Hints

Back to Problem

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 3.  Determine X(t)

                 Stoichiometry                  

                 Combine                          

                        Separate and Integrate

                                                           

                                                           

                  where                                

                                                           

Back to Hints

Back to Problem

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 4

Calculate conversion after 10 minutes

            300 K – No temperature correction needed for k1, kd since T = T1

                              Results the same for both catalysts

           

           

            For both catalysts 1 and 2 at 300 K

 

Back to Hints

Back to Problem

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Full Solution

Hint 1. Algorithm and a(t)

            Batch–

                  Mole Balance                  

                  Rate Law                         

                  Decay Law

            First-order decay law

 

 

 

 

 

   

Hint 2

Sketch a(t)

 

 

 

a(t) never equals zero for a first-order decay law

Hint 3.  Determine X(t)

                 Stoichiometry                  

                 Combine                          

                        Separate and Integrate

                                                           

                                                           

                  where                                

                                                           

Hint 4

Calculate conversion after 10 minutes

            300 K – No temperature correction needed for k1, kd since T = T1

                              Results the same for both catalysts

           

           

            For both catalysts 1 and 2 at 300 K

 

Back to Chapter 10