vacuume degassing question

inexperienced brewer here. The thought came to me that if methanol boils at a lower temperature than ethanol at atmosperic pressure than the same must be true under a vacuum. While degassing with a vacuum pump after the co2 is gone, would not the methanol boil off before you started to lose ethanol? what do you think?

sharkriver said:

inexperienced brewer here. The thought came to me that if methanol boils at a lower temperature than ethanol at atmosperic pressure than the same must be true under a vacuum. While degassing with a vacuum pump after the co2 is gone, would not the methanol boil off before you started to lose ethanol? what do you think?

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Depends on the pressure of the vacuum and the temperature. The CO2 is already a gas.

I guess what I mean to say that if the boiling points are different at atmospheric pressure they will be different at a vacuum regardless of the temperature or pressure that they are both under.?

The theory is certainly sound. You would need to be able to control both temperature and pressure simultaneously pretty accurately.

http://en.wikipedia.org/wiki/Vacuum_distillation

Don't get caught vacuum distilling.

Thanks for the heads up neo. Trying to get rid of alcohol (methanol) not collect it. I think that if I could keep a steady vacuum and monitor temperature with an immersed thermocouple, I could tell when the methanol was gone because the temperature would be constant and then change once the metanol was gone. It would then rise to the ethanol boiling point for that pressure. Sounds like fun. I have a few weeks to wait untill I can try it. Thanks so much for the help. On second thought I need to rethink this, some thing is not right

Feds don't care the reason or end result only the possible results. Legally its unlawful to freeze excess water out of booze.

Just saying, I've wasted money to have lawyers decode and explain the finer points just so I can make fuel.

How would you collect the methanol once it evaporated?

neo71665 said:

Feds don't care the reason or end result only the possible results. Legally its unlawful to freeze excess water out of booze.

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No, it's not.

I guess I didn't explain what I was doing. I made my first batch of applejack and I am trying to figure out a way to remove methanol from hard cider, applejack or home brewed wine. A guy at work told me about vacuum degassing of co2 with a real vacuum pump. He said that bubbles start out small at first(co2) and then get large (Methanol) after which if he continued the gas woul be ethanol. in theory. He believes that because the boiling points are different, you can boil off one without the other. Not trying to collect metahnol. Just get rid of it. Would be great not to drink that stuff.

But why? The amounts present in properly fermented beverages is negligible wrt any real concerns. All this effort to make a negligible toxin even more negligible is really just a waste, and the temps still needed to boil it off under a (residential) vacuum would almost certainly have an effect on taste. There are good reasons almost nobody (or even nobody at all, for all I know) does this, even on a commercial scale.

And this is coming from somebody who won't even consume aspartame because of the tiny amounts of methanol it produces. The only time I'd be worried about methanol in alcohol would be in illegally distilled liquor, and even then only from unscrupulous producers.

emjay said:

No, it's not.

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Freeze distillation is distillation. While most might overlook it as its not a big pot boiling in traditional style its still a form of distillation.

I had to jump through some major pita hoops to get a permit to distill fuel. When you're being watched you don't give them any reasons. I hired a lawyer to read over all the laws and give me a dumbed down summary.

emjay said:

But why? The amounts present in properly fermented beverages is negligible wrt any real concerns. All this effort to make a negligible toxin even more negligible is really just a waste, and the temps still needed to boil it off under a (residential) vacuum would almost certainly have an effect on taste. There are good reasons almost nobody (or even nobody at all, for all I know) does this, even on a commercial scale.

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Can't agree more

neo71665 said:

Feds don't care the reason or end result only the possible results. Legally its unlawful to freeze excess water out of booze.

Just saying, I've wasted money to have lawyers decode and explain the finer points just so I can make fuel.

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I thought it had to be proven that you had both the means and intention to commit the crime to be found guilty. If he was just getting rid of the methonal (which is pointless anyway as above has mentioned) then he could not be guilty of producing spirits by vacuum distinlling. He could be guilty of vacuum distilling as he would be intentding to do that. it depends on what the law actally prohibits.

neo71665 said:

Freeze distillation is distillation. While most might overlook it as its not a big pot boiling in traditional style its still a form of distillation.

I had to jump through some major pita hoops to get a permit to distill fuel. When you're being watched you don't give them any reasons. I hired a lawyer to read over all the laws and give me a dumbed down summary.

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I would expect that you have to jump through hoops and are watch carefully because what you are making can be drunk. I think it would be hard to prosecute someone for moonshining if they had a full blown still but there was no evidence of distilling (i.e. mason jars full of moonshine) - although is it not also illegal in some states just to own a still without a permit?
Whenever I hear about the issues you guys have with homebrewing It makes me glad I live in a country that only cares about getting the excise tax if I sell my alcohol

neo71665 said:

Freeze distillation is distillation. While most might overlook it as its not a big pot boiling in traditional style its still a form of distillation.

I had to jump through some major pita hoops to get a permit to distill fuel. When you're being watched you don't give them any reasons. I hired a lawyer to read over all the laws and give me a dumbed down summary.

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There has been much argument on this forum in the past. The administrator has specifically allowed discussion of it due to confirmation that it is, in fact, legal.

Freeze distillation is actually a misnomer. "Freeze concentration" would be the more technically accurate term. But either way, there is no question that it is legal within the United States. One BJCP category is even entirely defined by the process (eisbock), and is legally entered in competitions all the time.

emjay said:

There has been much argument on this forum in the past. The administrator has specifically allowed discussion of it due to confirmation that it is, in fact, legal.

Freeze distillation is actually a misnomer. "Freeze concentration" would be the more technically accurate term. But either way, there is no question that it is legal within the United States. One BJCP category is even entirely defined by the process (eisbock), and is legally entered in competitions all the time.

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I thought it was "fractionalized crystallization."

sharkriver said:

Thanks for the heads up neo. Trying to get rid of alcohol (methanol) not collect it. I think that if I could keep a steady vacuum and monitor temperature with an immersed thermocouple, I could tell when the methanol was gone because the temperature would be constant and then change once the metanol was gone. It would then rise to the ethanol boiling point for that pressure. Sounds like fun. I have a few weeks to wait untill I can try it. Thanks so much for the help. On second thought I need to rethink this, some thing is not right

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Hey Shark. First thing of note, your temperature will not change if you simply apply a vacuum. It is true that you are decreasing the pressure in the vapor space above the liquid, so in theory the vapor space would drop in temperature, as well as the liquid once it reaches equilibrium with the vapor. But your ambient heat input to the system would negate any minimal temperature drop you could theoretically measure. Your cider is going to simply sit at the same temperature of the surrounding environment. The temp will not increase. So the concept of monitoring the temperature to determine when the methanol has evaporated will not work.

Second thing of note. At 75F you would need to get down to about 3 psia in order to make methanol boil (see attached graph). To put that into perspective, that's equivalent to an elevation of almost 12,000 feet. On various occasions I have used an eductor for vacuum degassing to get rid of CO2 in my wines. The most I was ever comfortable pulling was down to 5 psia, and that was with a glass carboy!!! I've also been known to run with scissors

I mention this because you would most likely need a very special (i.e. expensive) setup to pull something like this off. The vacuum pump itself wouldn't be difficult to get your hands on. But the vessel you'd have to utilize would be pretty insane. Think thick walled metal vessel. Going from 5 psia to 3 psia doesn't sound like a lot, but it is extremely difficult to get those last few psi and you run an extremely high risk of imploding anything you're pulling the vacuum on.

OK, now I'll take off my Mr. Wizard hate and ask, have you looked into molecular sieves that might be selective for methanol? I know that in my business methanol absorbed on molecular sieves is a problem as some plants. But, the mole sieve we use also absorbs water, which you don't want.

And last note, my own personal interpretation of the Texas law (and yes I've read it) is that freeze concentration is illegal in my great state.

View attachment MeOHVapPress.pdf

Well thanks for all the good information. Looks like a waste of time. As for legal or not, not real worried about it. Privacy of the home and all that.