en2oh
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100% ethanol
Hi guys,
I've searched around here a little but didn't find the answer to this question.
Anyone care to take a shot at using propylene glycol to distill higher proof alcohol?
I'm looking for a discussion around extractive vs azeotropic distillation.
Thanks
En2oh
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DraconicAcid
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Why use propylene glycol instead of a better dessicant?
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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en2oh
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Regardless of solvent choice, I'm really looking at the principle of extractive vs azeotropic distillation. I found a patent using propylene glycol -
ethanol -water mixtures for extraction distillation.
En2of
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Dr.Bob
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If you want anyone to comment on the patent or any topic, it would be very helpful to reference it. We are not great at reading your mind as too
which patent or source you are talking about.
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Chemosynthesis
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I agree with Dr. Bob. Generally, the forum guidelines indicate to post references when making topics outside of the "Beginnings" section.
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Bert
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This goes to "beginnings" until and unless there is some documentation.
FYI, TONS of information on the production of anhydrous ethanol is to be found around here- UTFSE would really be a good idea!
Just off the top of my head: Removal of H2O as water of crystallization by various heat dehydrated salts, or via molecular sieves. Other more esoteric
methods are detailed here as well. But use of propylene glycol? You tell us-
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Bert
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Thread Moved
10-12-2014 at 17:41 |
macckone
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Ethylene glycol is usually used instead of propylene glycol.
In the ethylene glycol case ethanol distills over.
http://www.separationprocesses.com/Distillation/DT_Chp06c08....
Benzene is another commonly used substance.
In the benzene case it creates a lower boiling point
Azetrope with 3 components. That allows the water to
Be removed. First the three component azetrope comes over
then a two component mixture of ethanol and benzene.
Finally an almost pure ethanol is distilled. Cyclohexane
provides the same type of azetropic behavior.
https://books.google.com/books?id=gmnWZ1zNON0C&pg=PA262&...
[Edited on 11-12-2014 by macckone]
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en2oh
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Thanks for your feedback gents.
This paper examines propylene glycol as an entrainer, specifically as compared to ethylene glycol.
http://www.revistadechimie.ro/pdf/NEAGU%20PETRE%20M.pdf%201%...
It seems to be a more environmentally friendly alternative to benzene or ethylene glycol. I was struggling with my basic thermodynamics (coefficient
of activity) as it applies to separating an azeotrope of water/alcohol. I did grad studies in P Chem, but that was many years and at least one career
change ago.
I (wrongly ) hoped that this might generate a general discussion of azeotropic vs extractive distillation. I was wrong. My mistake.
En2oh
[Edited on 11-12-2014 by en2oh]
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en2oh
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Thanks for the link and your general comments. I appreciate your thoughts.
En2oh
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Bert
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Now that you have provided your source document, perhaps you will get some discussion on this.
Especially if you mention why/what about it interests you.
For a small batch, I'll probably stick with the processes mentioned earlier.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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en2oh
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Quote: Originally posted by Bert  | This goes to "beginnings" until and unless there is some documentation.
FYI, TONS of information on the production of anhydrous ethanol is to be found around here- UTFSE would really be a good idea!
Just off the top of my head: Removal of H2O as water of crystallization by various heat dehydrated salts, or via molecular sieves. Other more esoteric
methods are detailed here as well. But use of propylene glycol? You tell us- |
Thanks for your thoughts. As a point of clarification. Should that not have been U(of)TFSE would really be a good idea! Or more simply put, "UTFSE
next time!"? Is that what you were trying to say? Personally, as a TA and ultimately on faculty, I never found the "eF" word, even hidden in an
acronym, to be useful. YMMV, of course. 
Thanks again.
En2oh
[Edited on 11-12-2014 by en2oh]
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en2oh
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I really don't think that propylene glycol is acting as a desiccant in extractive distillation. It's acting as an entrainer. It's the thermodynamics
behind extractive distillation that I'm struggling with. A bit embarrassing for a guy who did PChem, but I was more of a "constrained motions in
glassy states" kind of guy, not a wet bench chemist.
Thanks
En2oh
[Edited on 11-12-2014 by en2oh]
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deltaH
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en2oh, download the small program called ChemSep lite, it will allow you to simulate this distillation and all the thermodynamics you
could want REALLY easily.
You will need to use the DECHEMA property model and an appropriate activity coefficient model, fortunately the built-in library already has the
required data for using the NRTL model for your components. NRTL is one of the more accurate activity coefficient models... just load the constants
for this system from the library.
If you don't have chemical engineering training, you will find the design of such distillation columns extremely challenging... but you can do it all
on this program and simulate the outcome.
[Edited on 11-12-2014 by deltaH]
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en2oh
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| Quote: Originally posted by deltaH | en2oh, download the small program called ChemSep lite, it will allow you to similate this distillation and all the thermodynamics you
could want REALLY easily.
You will need to use the DECHEMA property model and an appropriate activity coefficient model, to accurately describe the nonideal solution of
this system... very NB!
[Edited on 11-12-2014 by deltaH] |
Perfect! Thanks for the lead.
en2oh
(To be clear, NB in this case is for nota bene I.e. VeryI Important)
[Edited on 11-12-2014 by en2oh]
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deltaH
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You replied before I was completely done with the edit... you can use NRTL model in DECHEMA, see my post above...
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Chemosynthesis
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| Quote: Originally posted by deltaH | If you don't have chemical engineering training, you will find the design of such distillation columns extremely challenging... but you can do it all
on this program and simulate the outcome.
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Pff. It's just a glorified tubular heat exchanger. How complicated could it be?
Kidding!
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deltaH
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en2oh
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| Quote: Originally posted by deltaH | | You replied before I was completely done with the edit... you can use NRTL model in DECHEMA, see my post above... |
Thanks again
en2oh
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