Ecopolyol Production from Industrial Cork Powder via Acid Liquefaction Using Polyhydric Alcohols

Ecopolyol production from acid liquefaction of cork powder was studiedfor the first time using PEG 400 and glycerol as liquefaction solventsin the presence of sulfuric acid at moderate temperature and atmosphericpressure. The effect of the temperature, concentration of catalyst, andtime on the liquefaction yield has been investigated using a fixed setof reaction conditions namely, a liquefaction solvent mixture/corkpowder ratio of 5/1 and a solvent mixture PEG 400/glycerol ratio of90/10. The full-factorial design of experiments (DOE) 23 was applied toobtain an optimized set of liquefaction conditions aiming at minimizingthe residue content. The minimum residue contents experimentallyobtained in this study were 29 wt %, related to cork powder, which wereachieved at 150 C, 4 wt % of sulfuric acid, and 60 min. This valuecorresponds to 5 wt % of residue per total mass of reaction product.The polyols obtained under optimal conditions present similarcharacteristics (hydroxyl number value 219 mg(KOH)/g(polyol) andviscosity 2875 cP, at 25 degrees C) to those of petroleum-based polyolstypically used in the polyurethane foam industry.