Fabrication of a micellar heteropolyacid with Lewis–Brønsted acid sites and application for the production of 5-hydroxymethylfurfural from saccharides in water

Supramolecular complexes (C_nH_2n+1N(CH₃)₃)H₄PW₁₁TiO₄₀ (n = 4, 8, 12, 14, 16, and 18) consisting of heteropolyacids (HPAs) and amphiphilic quaternary ammonium were fabricated through self-assembly. (C₁₆H₃₃N(CH₃)₃)H₄PW₁₁TiO₄₀ was found to exhibit both Lewis acidity and Brønsted acidity. Meanwhile its amphiphilic property resulted in self-assembly in water, which could concentrate sugar molecules around the catalytic sites. Its unique structures contributed to its high performance in the production of 5-hydroxymethylfurfural (HMF) from saccharides with HMF yields of 53.7, and 50.8% for fructose and glucose in water, 66.4, 55.9, and 40.6% for sucrose, cellobiose and cellulose in biphasic solvent, respectively. Moreover, the catalyst can be recycled and reused about six times with negligible loss in activity.