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Topic: Isolation of m-xylene from a mix of xylenes  (Read 2081 times)

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Offline jfergua

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Isolation of m-xylene from a mix of xylenes
« on: February 01, 2018, 11:52:28 AM »
What is the technology of choice at industrial scale to separate m-xylene from the mixture of isomers?

Offline wildfyr

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Re: Isolation of m-xylene from a mix of xylenes
« Reply #1 on: February 01, 2018, 12:46:01 PM »
Did you try googling "separation of xylenes?" I got several papers such as these

http://pubs.acs.org/doi/abs/10.1021/ie50542a028
http://pubs.rsc.org/en/content/articlelanding/2015/cc/c4cc05329j#!divAbstract

The basis for them seems to be you find something that will solidify with only meta or para xylenes , then you can fractionally distill off the other from the ortho xylene because have 5°C BP seperation.

Offline jfergua

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Re: Isolation of m-xylene from a mix of xylenes
« Reply #2 on: February 01, 2018, 01:17:19 PM »
Thanks for your reply. Yes, we have googled the subject and apparently it is common practice to separate the ortho isomer from the m and p mixture by fractional distillation. Then the m + p mixture is subjected to fractional crystallization at very low  temperatures in the presence of eutectic modifiers to separate the m isomer. Yet we were hoping there was an easier economic way not requiring huge scales.
Can separation be accomplished via derivatization as, for example, after partial oxidation of the mix?

Offline zarhym

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Re: Isolation of m-xylene from a mix of xylenes
« Reply #3 on: February 02, 2018, 04:38:32 AM »
It is common at industrial scale to increase the pressure during the fractional distillation. By doing so, 5°C BP seperation at 1 atm can be much higher at increased pressure. On the other hand, this technique needs specialized equipments/facilities. 

Offline Enthalpy

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Re: Isolation of m-xylene from a mix of xylenes
« Reply #4 on: February 02, 2018, 08:22:29 AM »
These patents (same inventor) recommend azeotropic distillation to separate the meta from para (1K difference):
https://www.google.com/patents/US5039380
https://www.google.com/patents/US5445715
https://www.google.de/patents/US5466345
It could be cheaper than cold.

Could that distillation be an application for my thingy there? Just a way to put more plates in the same volume
www.chemicalforums.com/index.php?topic=57335

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