Production of High-Purity Allyl Alcohol by the Salting-Out Method from Formic Acid-Mediated Deoxydehydration of Glycerol

Formic acid-mediated deoxydehydration of glycerol has emerged as an attractive approach to produce allyl alcohol; however, separation of allyl alcohol by distillation is not a straightforward task from the mixture of allyl alcohol, formic acid, and water because of their very close boiling point. A new route to separate allyl alcohol with high purity has been developed by the precipitation, distillation, and salting-out process. Among 11 salts, NaCl, K₂HPO₄, and K₂CO₃ could easily induce the liquid–liquid phase splitting. K₂CO₃ exhibits the best salting-out effect in a single salt system. Meanwhile, the solubility of allyl alcohol in the organic phase could be predicted by the mass fraction of salt. The allyl alcohol purity of >99.9% could be achieved by using 35% K₂CO₃ + 25% K₂HPO₄. The results also provide valuable references to obtain high-purity allyl alcohol for all the glycerol to allyl alcohol routes, because it is indispensable to separate allyl alcohol from its aqueous solution.