Membrane Reactors

Question 1

To increase the yield of a reaction that is highly reversible over the temperature range of interest we can

Answer 1

To increase the yield of a reaction that is highly reversible over the temperature range of interest we can
…
remove one of the products from the reactors, forcing the equilibrium of the reaction to “the right”.

Question 2

A catalytic membrane reactor is?

Answer 2

A membrane reactor combines a membrane-based separation with a catalytic reactor.

Question 3

What is volume index?

Answer 3

Volume index is a function of feed pressure, you can get a reduction in plant size and related cost by decreasing the volume index by increasing the feed pressure.

Volume index is decreasing as a function of feed pressure.

Reduce reactor volume by controlling operating pressure!

The volume index compares the volume of the catalytic membrane with the traditional plug flow reaction without separation function.

Question 4

What happens when you increase the pressure on the feed side?

Answer 4

increase the pressure on the feed side you = larger driving force = significantly decrease the volume required.

Question 5

Explain microporous membrane material?

Answer 5

Microporous membrane is permeable also by other gases, so less selective than Pd-based.

Question 6

Explain Pd membrane material?

Answer 6

The hydrogen molecules will transfer to the membrane, and then undergo dissociative chemisorption, moving through the membrane as hydrogen atoms as the membrane will rip the molecules apart. Therefore, the membrane is very highly selectivity as the molecules must dissociated adsorption to move through the membrane.

Question 7

Name the two types of membrane reactors?

Answer 7

Extractor Type

Distribution/contactor type

Question 8

What are the key things about Extractor Type?

Answer 8

1. Thermodynamically controlled reactions
2. Gibbs energy is zero or very near
3. K constant ~= 1
4. Operating near/at equilibrium
5. Conversion enhancement

Reaction must be sufficiently fast compared to the mass transport through the membrane

Selectively improvements can be found by selectively removing reaction rate inhibitors.

Question 9

What are the key things about Distributor/contactor type?

Answer 9

1. Kinetically controlled reactions
2. Gibbs energy is very negative
3. K constant&raquo_space; 1 (much greater)
4. Operating not at equilibrium
5. Selectivity enhancement

The desired product is usually an intermediate in a consecutive reaction or is a product in parallel reactions, do not want the reaction to go to complete conversion.

With a distributed feed along the reactor the flow rate downstream usually increases and the Residence time at the catalytic sites will be reduced.

Enhances the selectivity, by controlling the yield through controlling the (Residence time) the flow rate.

Question 10

Catalytic membrane reactor vs membrane reactor

Answer 10

uses a catalyst as its membrane compared to an inert membrane.