Pyrolysis oil and organic acids

Pyrolysis oil water phase - EMPYRO project - Pyrolysis oil production - Bio-oil production - Pyrolysis plant in EuropeDuring pyrolysis oil upgrading a light yellow, transparent aqueous liquid is produced. This liquid contains acetic acid, formic acid, propionic acid and a small amount of furfural. Acetic acid appears in sufficient quantities to warrant research on its recovery.

The separation of acetic acid and water by simple rectification is very difficult, and is rather costly. Liquid-liquid extraction seems to offer a good alternative, using ethyl acetate and methyl isobutyl ketone as solvents. For low concentrations (as in the current project) ethyl acetate is normally preferred. The bottom products of the solvent recovery column contain the acetic acid with a typical concentration between 95-100%. The effect of the presence of formic acid and propionic acid on this process is not known and will be further investigated.

Commercially less established is the use of pervaporation systems to separate acetic acid and water. The suitability of this technology will also be researched. Typically polymer based membranes will be applied, at relative low temperatures (25-50oC).