Sciencemadness Discussion Board

Filter issue recycling pet

devilunix - 24-8-2017 at 09:40

hello folks.im trying to recycle pet as dioctyl terephthalate .Reacting with octanol.After reaction i see white slime in product.It makes filter hard.Cant pass product through filter.i think slime is monomer of pet unreacted.Any idea to get rid of ?

Melgar - 24-8-2017 at 10:23

First off, try and all-caps acronyms, especially if they're subject to multiple interpretations. I came in here wondering if you got cut off writing "petroleum ether" or something.

Second, it breaks down into oligomers first, before gradually breaking down further. It sounds like that's what you have. You'd probably have to use a large excess of octanol to drive the reaction towards dioctyl terephthalate.

Boffis - 24-8-2017 at 11:01

@ devilunix; most of us can't mind read and my crystal balls are getting a bit mirky these days so could you please give us a bit more detail. For instance did you isolate the terephthalic acid first? Under what conditions did you try to esterify it? Are we talking n- , iso- or some other octanol isomer.

Sodium bicarbonate solution can be used to remove the un-reacted terephthalic acid and any mono-ester. Its possible that any free mono-ester acts as an emulsifying agent but turning it into a salt may not cure this.

devilunix - 24-8-2017 at 12:16

Quote: Originally posted by Boffis  
@ devilunix; most of us can't mind read and my crystal balls are getting a bit mirky these days so could you please give us a bit more detail. For instance did you isolate the terephthalic acid first? Under what conditions did you try to esterify it? Are we talking n- , iso- or some other octanol isomer.

Sodium bicarbonate solution can be used to remove the un-reacted terephthalic acid and any mono-ester. Its possible that any free mono-ester acts as an emulsifying agent but turning it into a salt may not cure this.

sorry.i use isooctanol.i dont isolate terephtalic acid.just put pet and isooctanol into reactor.heat it up.use titan catalyst.max 1.4bar 225 celcius degree temperature.

[Edited on 24-8-2017 by devilunix]

devilunix - 24-8-2017 at 12:20

Quote: Originally posted by Melgar  
First off, try and all-caps acronyms, especially if they're subject to multiple interpretations. I came in here wondering if you got cut off writing "petroleum ether" or something.

Second, it breaks down into oligomers first, before gradually breaking down further. It sounds like that's what you have. You'd probably have to use a large excess of octanol to drive the reaction towards dioctyl terephthalate.

i use 1:3 pet/alcohol weight

Melgar - 25-8-2017 at 19:10

Quote: Originally posted by devilunix  
i use 1:3 pet/alcohol weight

You're dissolving your pets in alcohol? Oh, right... PET.

That's really only a 50% excess. Try with like a 200% excess on a small scale and see if it improves? I'm assuming it can be recycled anyway, no?

Boffis - 27-8-2017 at 12:26

Do you have a reference to this "titan" catalyst and indeed to the whole process? I have only seen references to direct alcoholisis with low weight methanol and ethanol they didn't mention C8 alcohols.