Sciencemadness Discussion Board

Information on Wood/Lignin Pyrolysis?

Kovoc - 5-7-2024 at 19:01

I have recently been doing research into the pyrolysis of lignin as a source of aromatic compounds (specifically benzene). I am curious if anyone has experience doing this on a small scale. I have a read a few papers on the matter, but they tend to be either very recent, with a focus on using strange catalysts for a "green" production of aromatics; or they are from over a century ago and are more concerned with the commercially valuable lighter compounds (i.e., methanol, acetic acid, etc.) than they are the aromatics.

The products of the pyrolysis should be things like isoeugenol, vanillin, etc. Therefore, I would assume just oxidizing them and then distilling them again with a strong alkali would work to turn them into phenols. However, if there is a more efficient way of doing this I would be very interested to know.

bnull - 6-7-2024 at 05:15

Quote: Originally posted by Kovoc  
I have a read a few papers on the matter, but (...) they are from over a century ago and are more concerned with the commercially valuable lighter compounds (i.e., methanol, acetic acid, etc.) than they are the aromatics.

Because petroleum cracking hadn't been discovered or widespread back then. The only sources of lighter compounds were fermentation and wood pyrolysis. Aromatics came from coal tar.

A better source of benzene is PET. There are several threads about the process here in the forum. It is in a sense more well-researched than wood pyrolysis.

If you still prefer to pyrolyse wood, notice that the products obtained depend on what wood you are using, the temperature to which the wood is submitted, the pressure. It is not trivial. Check this paper: H. Kawamoto, "Lignin pyrolysis reactions".

Mateo_swe - 7-7-2024 at 19:42

If you want to make benzene i would use sodium benzoate (spice section in foodstore) and NaOH.
Mix in a paintcan and make a hole for the distillation adapter and condenser (simple distillation) and then heat the paintcan with a camping gas burner.
I have done this many times. You will get a yellow/orange distillate that when distilled again get you relative pure colorless benzene.
There is a lot of YT videos of this procedure, one from nilered that is explaining the procedure good.

The pyrolysis of wood would be a similar procedure but you would get a mixture of products that you would need to separate and this isn't always so easy.

[Edited on 2024-7-8 by Mateo_swe]