A series of polyvinylpyrrolidone-stabilized heteropolyacids(PVP-HPAs)are generated by self-assembly of HPAs and PVP in methanol.The PVP-HPAs are then employed as catalysts for the synthesis of poly(oxymethylene)dimeth...A series of polyvinylpyrrolidone-stabilized heteropolyacids(PVP-HPAs)are generated by self-assembly of HPAs and PVP in methanol.The PVP-HPAs are then employed as catalysts for the synthesis of poly(oxymethylene)dimethyl ethers(DMMn,n1)by the methanolysis of trioxane.The results suggest that the acidity of PVP-HPAs is tunable by changing the ratio of PVP and HPAs,which is a key factor for the selectivity of the DMMn product.By optimizing the composition and reaction conditions,two types of PVP-HPA,PVP-phosphotungstic acid(PVP-HPW)in a PVP/HPW ratio of 1/4:1 and PVP-silicotungstic acid(PVP-HSi W)in a PVP/HSi W ratio of 1/4:3/4,respectively afford 52.4%and 50.3%yields of DMM2–5.The optimized catalysts are reusable for a minimum of 10 times without a significant drop in performance.展开更多
基金financially supported by the National Basic Research Program of China(2011CBA00508)the National Natural Science Foundation of China(21173175,21303141)+1 种基金the Research Fund for the Doctoral Program of Higher Education(20110121130002)the Program for Changjiang Scholars and Innovative Research Team in University(IRT1036)
文摘A series of polyvinylpyrrolidone-stabilized heteropolyacids(PVP-HPAs)are generated by self-assembly of HPAs and PVP in methanol.The PVP-HPAs are then employed as catalysts for the synthesis of poly(oxymethylene)dimethyl ethers(DMMn,n1)by the methanolysis of trioxane.The results suggest that the acidity of PVP-HPAs is tunable by changing the ratio of PVP and HPAs,which is a key factor for the selectivity of the DMMn product.By optimizing the composition and reaction conditions,two types of PVP-HPA,PVP-phosphotungstic acid(PVP-HPW)in a PVP/HPW ratio of 1/4:1 and PVP-silicotungstic acid(PVP-HSi W)in a PVP/HSi W ratio of 1/4:3/4,respectively afford 52.4%and 50.3%yields of DMM2–5.The optimized catalysts are reusable for a minimum of 10 times without a significant drop in performance.
