Hydrolysis and alcoholysis of polysaccharides with high efficiency catalyzed by a(C_(16)TA)_xH_(6-x)P2W_(18)O_(62) nanoassembly

摘要

Wells-Dawson structured heteropolyacid (HPA) H6P2W_(18)O_(62) was first used as a precursor to fabricate a micellar assembly, [C_(16)H33N(CH3)3]xH_(6-x)P2W_(18)O_(62) (abbreviated as (C_(16)TA)_xH_(6-x)P2W_(18)O_(62)). Hydrolysis and methanolysis of polysaccharides including cellobiose, starch, and cellulose were catalyzed by (C_(16)TA)_xH_(6-x)P2W_(18)O_(62).(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)H5P2W_(18)O_(62) 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.