Autocatalytic Reactions

Question 1

Define an autocatalytic reaction.

Answer 1

A reaction in which the product of the reaction acts as a catalyst.

Question 2

Describe how reaction rate changes with the progress of an autocatalytic reaction.

Answer 2

At the start of the reaction, the rate is slow as there is very little product. As product forms, the rate increases and reaches a maximum, then begins to fall as the reactant (A) is consumed.

Question 3

Draw the 1/r_A against conversion curve for an autocatalytic reaction with no product in the feed.

Answer 3

Question 4

How does the efficiency of PFRs and CSTRs change with the conversion of an autocatalytic reaction?

Answer 4

At low conversions, the CSTR is superior.

At high conversions, the PFR is superior.

There is a conversion at which both the CSTR and PFR are equally efficient.

Question 5

How must a PFR be set up to deal with an autocatalytic reaction?

Answer 5

It must have a recycle as it will not work if it is not continually primed with product.

Question 6

What is the equation for recycle ratio?

Answer 6

R = (volume of fluid returned to the reactor)/(volume leaving the system)

Question 7

Draw a PFR with a recycle stream and label all the flowrates.

Answer 7

Question 8

What is the recycle ratio of a normal PFR?

Answer 8

0

Question 9

What is the recycle ratio of a CSTR?

Answer 9

Infinity