Distilling Methanol

Dropout · Post by **Dropout** » Mon Apr 04, 2005 10:14 am

Good afternoon everyone.

Love the forum. Lots of great info.

I have a solution that is comprised of about 50% glycerol, 40% methanol and about 10% water and I need to reclaim the methanol.

Am I correct in assuming that the solution that you all start with has a much higher percentage of water and that affects the purity of the distillate? If so, what would be a reasonable purity that I could attain with a pot or reflux setup? Glycerol boils at something like 325C so the only issue will be the water.

Would all the typical calculations for column size etc still be appropriate for methanol? My plans are to use a 50 litre batch size.

Thanks in advance.

Dropout

KatoFong · Post by **KatoFong** » Mon Apr 04, 2005 10:37 am

Just out of curiosity, why are you distilling methanol?

Guest · Post by **Guest** » Mon Apr 04, 2005 10:43 am

I have a small system to make biodiesel. The byproduct contains glycerol and methanol. The methanol can be reused if it can be reclaimed.

Dropout

Yttrium · Post by **Yttrium** » Mon Apr 04, 2005 11:24 am

All the calculations for ethanol should work fairly well for methanol. Since the boiling temp of methanol is less than that of ethanol, the equations on this site will underestimate the purity of your product by a little bit.

With a reflux still, I would imagine that you should have no problem achieving 95%+ purity. If you were to distill the solution once in a pot still, you'd probably get around 75-80% purity of methanol.

level Joe · Post by **level Joe** » Mon Apr 11, 2005 3:17 pm

Is glycerol a sugar or an alcohol ? If its a sugar, would there be a concern of it burning to the still with only 5%+/- water left in solution? Just a question I thought I would ask to someone who might know.

The Chemist · Post by **The Chemist** » Tue Apr 12, 2005 6:26 am

Sugars are carbohydrates. Carbohydrates are polyhydroxy aldehydes or ketones. Glycerol is a triol (polyhydroxy), but has no carbonyl (aldehyde/ketone) bit. So, glycerol (also called glycerine) is an alcohol, not a sugar.

That said, glycerol is a syrupy liquid 0.6 times as sweet as sugar (table), and boils with decomposition (burns) at 290 deg C. So, unless you're heating to 554 deg. F

you should be okay.

level Joe · Post by **level Joe** » Wed Apr 13, 2005 4:43 pm

Thanks Chemist
The first 1/2 of that was ovar my head but the second part answered any questions.

Thanks again
Joe