Abstract:

Agarose was used as the starting material, and CuCl₂, NiCl₂, MnCl₂, MgCl₂, FeCl₃, AlCl₃, ZrOCl₂ and SnCl₄ were respectively used as catalysts to convert agarose into 5-hydroxymethylfurfural(5-HMF) and levulinic acid(LA). Preferred catalysts were screened out for the conversion of agarose. The effects of reaction parameters such as water content, catalyst loading, reaction temperature and reaction time on the reaction were investigated in detail. The results demonstrated that when 50 mg of agarose was used as the feedstock with ZrOCl₂ as the catalyst and DMSO as the solvent, 5-HMF yield of 26.9% and LA yield of 24.7% could be achieved in 1 mL DMSO/H₂O mixed solvent with a volume ratio of 8:2 and ZrOCl₂ loading of 10% to the amount of substance of monosaccharide in agarose at 140℃ for 60 min. Mechanism analyses indicated that agarose was hydrolyzed into aldose, which underwent subsequent isomerization and dehydration to produce 5-HMF. 5-HMF could be further converted into LA catalyzed by acid catalyst.

Key words: agarose, 5-hydroxymethylfurfural, levulinic acid, ZrOCl₂