Syntheses of 5-hydroxymethylfurfural through glucose dehydration in diphasic solvent system on ZrO₂ and SO₄^2-/TiO₂-SiO₂ catalyst

Synthesis of 5-hydroxymethylfurfural (5-HMF) from glucose in water-dimethyl sulfoxide diphasic system using solid base ZrO₂ and SO₄^2-/TiO₂-SiO₂ catalysts was studied. The effects of calcining temperature, Ti/Si ratio in SO₄^2-/TiO₂-SiO₂, catalyst dosage, and mass ratio of ZrO₂ and SO₄^2-/TiO₂-SiO₂ mixture on 5-HMF yield were evaluated. Both the base and acid catalyst exhibited best performance when calcined at 450°C. The optimal Ti/Si ratio was found to be 4:1. ZrO₂ and SO₄^2-/TiO₂-SiO₂ mixture worked much better than ZrO₂ or SO₄^2-/TiO₂-SiO₂ alone. The optimal catalyst dosage was found to be 20% of the glucose amount (w). Instrumental characterization of the catalysts indicate that mild base and acid sites are suitable for conversion of glucose to 5-HMF, and the base and acid catalysts in the mixture do not interact chemically to a noticeable extend that influences the functionality. The water-organic diphasic system proved to be efficient in catalytic transformation of glucose to 5-HMF.