Hydrolysis and alcoholysis of polysaccharides with high efficiency catalyzed by a (C16TA)xH6−xP2W18O62 nanoassembly

Abstract

Wells–Dawson structured heteropolyacid (HPA) H₆P₂W₁₈O₆₂ was first used as a precursor to fabricate a micellar assembly, [C₁₆H₃₃N(CH₃)₃]_xH_6−xP₂W₁₈O₆₂ (abbreviated as (C₁₆TA)_xH_6−xP₂W₁₈O₆₂). Hydrolysis and methanolysis of polysaccharides including cellobiose, starch, and cellulose were catalyzed by (C₁₆TA)_xH_6−xP₂W₁₈O₆₂. (C₁₆TA)H₅P₂W₁₈O₆₂ showed the highest activity, with hydrolysis rates of cellobiose, starch and cellulose of 0.74, 0.02, 0.0.8 min⁻¹ at 100 °C, 120 °C and 160 °C, respectively, much better than Keggin H₃PW₁₂O₄₀. Meanwhile, (C₁₆TA)H₅P₂W₁₈O₆₂ performed 94.8% conversion of cellulose into methyl levulinate (MLA) with 58.5% yield in methanol. The high activity of the catalyst was attributed to the synergistic effect of a high concentration of acid, more substrates adsorbed, and the oxidizing ability of (C₁₆TA)H₆P₂W₁₈O₆₂. The results demonstrated that it was an effective and reusable catalyst for the production of glucose and MLA from polysaccharides.