Sciencemadness Discussion Board

Destructive distillation of wood (& other organic material) & coal

RogueRose - 17-2-2017 at 03:13

I've read a number of places about distilling wood to make methanol and acetic acid along with some tars. Some videos show the output of the still going into a collection bucket of water and it bubbles then all gases escape - the methanol, AA and tars are collected here in a brown liquid. I guess this can later be distilled again to get a purer product but I'm not certain about how easy separation is with a simple still (non fractioning column).

I also saw some videos on what some people call "wood vinegar" which I am guessing is simply a mixture of the methanol, AA and the tar. It is touted as a cure-all for just about everything on the farm as well as being a pesticide, fungicide, weed killer and fertilizer - along with healing properties for skin and fur/hair conditions. (they do use pine tar and coal tar for some skin conditions - in low % though). I've read there may be about 200 compounds coming over in the gas, such as acetone and MEK - but that number seems high.

The amount of methanol produced from a ton of wood was quoted at 620lbs which seems reasonable especially since the remaining carbon can be used as charcoal or some use it as a soil additive.

I'm going to try to make a still to do this and have access to a 20 and 55 gal drum as well as a 5 gal metal bucket which I might try to start. I'm wondering whether a condenser is needed if the recovery liquid is deep enough to allow the bubbles to cool and absorb as they travel to the surface. I can make a condenser but am worried that doing so would cause tar build up - but IDK what temp the tar would cause clog-up. I'd prefer running a condenser as it is pretty easy to setup.

I'd also like to try destructive distillation of LD/HDPE at some point to see if I can get ethylene and if I can make the same still do both jobs, that would be awesome.

PHILOU Zrealone - 17-2-2017 at 03:46

Just read how much chemicals are generated into cigarette smoke and you would know 200 compounds is quite reallistic.

More likely with HDPE you will get cracking to various MW alcenes and alcanes ... some as volatile liquids and other gaseous.

Maybe start with candle wax is like PE but of shorter MW.

Marvin - 17-2-2017 at 04:02

Your expected yield of methanol sounds way off. A quick Google suggests 16 kg methanol from every 1000 kg of air dry hardwood, or about 1/20th of the numbers you state. Could the yield you found be as a percentage of distillate?

RogueRose - 18-2-2017 at 22:05

Quote: Originally posted by Marvin  
Your expected yield of methanol sounds way off. A quick Google suggests 16 kg methanol from every 1000 kg of air dry hardwood, or about 1/20th of the numbers you state. Could the yield you found be as a percentage of distillate?

So you are saying that ~5 gallons of methanol per ton of wood? I find that difficult to believe as well but I'll have to see what king of yield I get before I really trust any numbers. I'm curious how much charcoal is left at the end of the process as that will make a huge difference in what potential yields could be.

I have a feeling that the number I quoted might be for wet wood and the yield is everything that comes over, methanol, AA, tar, water and all the misc compounds.

pneumatician - 26-2-2017 at 21:58


carbo.gif - 166kB

macckone - 27-2-2017 at 09:39

Paper says 0.8 to 2.1% methanol.

It has a good yield table.

I would suggest two stage method of collection.
stage one is straight tube into water, which will
condense your nasty tars and a good percentage
of other stuff and then an off gas condenser to
collect volatile compounds that aren't significantly
above the boiling point of water.

The water needs to be kept cool or your off gas
condensor will do all the work so you may want
a cooling coil in the water.

The jersey rebel - 28-2-2017 at 11:51

charcoal is much safer to burn than wood since there's little to no smoke produced so it could be sold as fuel to communities. or it can be used as activated carbon for some types of wood with a higher hydrocarbon percentage. about the 200 compounds assessment, I think that's likely a gross underestimation. probably thousands of compounds are produced, each wood or material producing different amounts of or different molecules during decomposition/pyrolysis. the tar can be steam reformed to make H2 gas or cracked into smaller hydrocarbons that can be used as an alternative to gasoline. This is a project I do want to try though i don't have much space:(

macckone - 28-2-2017 at 15:57

The primary danger of wood and charcoal is carbon
monoxide. So no it is not inherently safer than wood.

Daffodile - 28-2-2017 at 16:11

I tried it and posted the results, albeit maybe with a different account. My yields were extremely low as I got a lot of water, some flammable vapour, and otherwise essentially nothing I could easily classify as Methanol.

macckone - 1-3-2017 at 08:34

The amounts of methanol compared to water is small (30:1).
About triple the methanol is the acetic acid.
So it requires distilling the resulting product and
if you don't have sufficient cooling that flammable
vapor will contain all of your methanol.

That is why I recommend two stage cooling with
an inner cooler in the water tank. There are good
books from the 1800s that describe the process in detail.