Highly effective transformation of carbohydrates to 5-Hydroxymethylfurfural with Al- montmorillonite as catalyst

We prepared the catalysts through the ion-exchange of natural calcium montmorillonite with an aqueous aluminum trichloride solution. Al3+ was a good Lewis acid catalyzing the isomerization of glucose to fructose, and the partially hydrolyzed Al−OH groups acted as Brønsted acid for the dehydration of fructose to HMF, which can be extracted by THF with a high yield.