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Author: Subject: Drying formic acid with molecular sieves - CO risk?
Stibnut
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[*] posted on 22-2-2017 at 14:37
Drying formic acid with molecular sieves - CO risk?


I've got a very basic question. If I have 95% formic acid, and I want to make it anhydrous, would 4A molecular sieves be a good choice for drying?

The main reason I ask is that I don't want to accidentally evolve CO. Does anhydrous formic acid decompose much more rapidly than 95%, and is there any chance that molecular sieves would catalyze this decomposition?
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Cryolite.
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[*] posted on 22-2-2017 at 14:50


You wouldn't form carbon monoxide, but you would destroy your sieves! Molecular sieves do not tolerate acid.
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PHILOU Zrealone
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[*] posted on 22-2-2017 at 15:19


Quote: Originally posted by Cryolite.  
You wouldn't form carbon monoxide, but you would destroy your sieves! Molecular sieves do not tolerate acid.

And he will also contaminate his formic acid with soluble stuffs from the reaction of the molecular sieve with the acids...




PH Z (PHILOU Zrealone)

"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Stibnut
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[*] posted on 22-2-2017 at 15:25


D'oh! Okay, I won't try that.

What about MgSO4?
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Boffis
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[*] posted on 22-2-2017 at 22:30


Formic acid is up-graded by azeotropic distillation, usually with n-heptane or a petroleum ether with a close boiling range. The formic acid distils over preferencially with the heptane. I have tried it but its not as easy as it sounds as a batch process because a lot of heptane distils for a small amount of acid so you need a system to recycle the heptane continously and thats where it gets complex.
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