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Dear All,
I am a Chemical Engineering undergraduate student from the National University of Singapore.
I would like to consult you about some questions in separations.
If I want to separate Acrylonitrile from Acetonitrile using water as the solvent or entrainer,
which distillation method should I use?
Acrylonitrile and Acetonitrile have close boiling points. However, they do not form azeotropes with one another. It will be very difficult to separate these two components from one another without the assistance of another chemical.
Therefore, I have decided to add water to increase the volatility of acrylonitrile with respect to acetonitrile. However, water will form azeotrope with acrylonitrile and acetonitrile. In the article that you wrote, if I use water as a solvent, this does not seem to qualify as extractive distillation. However, the professors in my university have insisted to call it extractive distillation and I m very sure that most students working on this project do not even know why! Can you please share abit of your insight with me pertaining to this matter?
I would be very grateful to you.
Thanks alot.
Yours sincerely
Nicholas
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Extractive Or Azeotropic Distillation?
Started by Guest_Nicholas Soong_*, Feb 24 2006 10:03 PM
3 replies to this topic
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#2
Ankur Shah
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- Members
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Posted 25 February 2006 - 01:26 AM
hey!
there is a basic difference between azeo and ED (extractive distillation). as for your case here, since water shall form an azeo, you can use water for azeotropic distillation. but what matters more than your primary separation, is whether or not you can separate water and acrylonitrile easily. if you can NOT do that, then you are better off with extractive distillation.
this simply means that when you do ED, the extractive agent, simply changes the VLE of the system, to support the distilltion of one component from the other.
tell me if this makes sense. else shall explain in more detail.
Ankur
there is a basic difference between azeo and ED (extractive distillation). as for your case here, since water shall form an azeo, you can use water for azeotropic distillation. but what matters more than your primary separation, is whether or not you can separate water and acrylonitrile easily. if you can NOT do that, then you are better off with extractive distillation.
this simply means that when you do ED, the extractive agent, simply changes the VLE of the system, to support the distilltion of one component from the other.
tell me if this makes sense. else shall explain in more detail.
Ankur
#3
chemsep05
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- Members
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- 31 posts
Veteran Member
Posted 01 March 2006 - 01:27 AM
A classic Azeotrope is Ethanol Water, Azeotropic distillation attempts to find a way around the Azeotrope to get a higher purity, while, Extractive distillation is exactly what it says extraction, There may be side streams that strip certain chemicals off at different stages, in some ways it is similar to azeotropic
#4
Guest_Sankesh Sundareswar_*
Guest_Sankesh Sundareswar_*
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- guestGuests
Posted 02 March 2006 - 06:13 AM
Hi Mr.Soong,
I have finished my master's in Chemcial Process Design from UMIST, Manchester,UK.
Extractive distillation is the term used when a high boiling solvent is used as a seperating agent. The key to the definition of extractive distillation is that the solvent or entrainer is the highest boiling component and has a boiling point much higher than the other components in the feed mixture. Wether azeotropes is formed or not in the system is not a criteria for definition. I would also like you to see if the definition involves the specification of number of feeds. I think if you have two feeds in the column with the upper feed being relatively pure solvent it is definitely extractive distillation (but I can't seem to clearly remember this). Please reffer Seperation Princliples by Seader, it is an excellent book and will clear your doubts well.
Regards,
sankesh
icholas Soong' date='Feb 24 2006, 10:03 PM' post='4839']
Dear All,
I am a Chemical Engineering undergraduate student from the National University of Singapore.
I would like to consult you about some questions in separations.
If I want to separate Acrylonitrile from Acetonitrile using water as the solvent or entrainer,
which distillation method should I use?
Acrylonitrile and Acetonitrile have close boiling points. However, they do not form azeotropes with one another. It will be very difficult to separate these two components from one another without the assistance of another chemical.
Therefore, I have decided to add water to increase the volatility of acrylonitrile with respect to acetonitrile. However, water will form azeotrope with acrylonitrile and acetonitrile. In the article that you wrote, if I use water as a solvent, this does not seem to qualify as extractive distillation. However, the professors in my university have insisted to call it extractive distillation and I m very sure that most students working on this project do not even know why! Can you please share abit of your insight with me pertaining to this matter?
I would be very grateful to you.
Thanks alot.
Yours sincerely
Nicholas
[/quote]
I have finished my master's in Chemcial Process Design from UMIST, Manchester,UK.
Extractive distillation is the term used when a high boiling solvent is used as a seperating agent. The key to the definition of extractive distillation is that the solvent or entrainer is the highest boiling component and has a boiling point much higher than the other components in the feed mixture. Wether azeotropes is formed or not in the system is not a criteria for definition. I would also like you to see if the definition involves the specification of number of feeds. I think if you have two feeds in the column with the upper feed being relatively pure solvent it is definitely extractive distillation (but I can't seem to clearly remember this). Please reffer Seperation Princliples by Seader, it is an excellent book and will clear your doubts well.
Regards,
sankesh
icholas Soong' date='Feb 24 2006, 10:03 PM' post='4839']
Dear All,
I am a Chemical Engineering undergraduate student from the National University of Singapore.
I would like to consult you about some questions in separations.
If I want to separate Acrylonitrile from Acetonitrile using water as the solvent or entrainer,
which distillation method should I use?
Acrylonitrile and Acetonitrile have close boiling points. However, they do not form azeotropes with one another. It will be very difficult to separate these two components from one another without the assistance of another chemical.
Therefore, I have decided to add water to increase the volatility of acrylonitrile with respect to acetonitrile. However, water will form azeotrope with acrylonitrile and acetonitrile. In the article that you wrote, if I use water as a solvent, this does not seem to qualify as extractive distillation. However, the professors in my university have insisted to call it extractive distillation and I m very sure that most students working on this project do not even know why! Can you please share abit of your insight with me pertaining to this matter?
I would be very grateful to you.
Thanks alot.
Yours sincerely
Nicholas
[/quote]
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