The molecular sieves supported TiO 2/SO 2- 4 catalyst was prepared by the liquid phase precipitation,then its preparation conditions were investigated in detail.The results indicated that the pH value of solution was ...The molecular sieves supported TiO 2/SO 2- 4 catalyst was prepared by the liquid phase precipitation,then its preparation conditions were investigated in detail.The results indicated that the pH value of solution was adjusted to 1.8,the mass ratio of TiO 2 to molecular sieves was 0.13∶100,the water in the system must be evaporated slowly at 90℃.And the best active temperature of catalyst was 50℃.The factors that had influence on the esterification of levulinic acid with alcohol were also discussed,the optimum reaction conditions were 5∶100(mass ratio) of catalyst to acid,5∶6(volume ratio) of alcohol to acid,oil bath temperature being kept at 110℃ and suitable reaction time being 1.5h.Under such conditions,the ester yield could be as high as 96.5%.展开更多
The synthesis of carbon-based, heterogeneous sulphonic catalysts for the production of levulinate esters. Hydrothermal treatment at moderated temperatures was employed to generate highly functional carbonaceous materi...The synthesis of carbon-based, heterogeneous sulphonic catalysts for the production of levulinate esters. Hydrothermal treatment at moderated temperatures was employed to generate highly functional carbonaceous materials, referred to as hydrothermal carbons (HTCs), from both glucose, cellulose and rye straw. The products were sulfonated to generate solid acid-catalysts. Characterisation of the as-synthesised materials as well as catalyst activity tests were performed. SEM images indicate the micrometre-sized particles present in both HTCs were largely unaffected by sulfonation, although cellulose-derived HTC displayed signs of inadequate hydrolysis. FT-IR spectroscopy and elemental analysis confirmed successful incorporation of sulphonic groups. 13C solid state NMR, in addition to TGA, elucidated the carbons’ structural composition and supported the common-ly-proposed hydrothermal carbonisation mechanism. Finally, the catalysts were tested via levulinic acid-ethanol esterification and gave high conversion and ester-selectivities (> 90%).展开更多
A series of metal salt-modified carbon catalysts had been prepared to study the selective transformation of various carbohydrates into ethyl levulinate in an ethanol medium. The specific textural and chemical characte...A series of metal salt-modified carbon catalysts had been prepared to study the selective transformation of various carbohydrates into ethyl levulinate in an ethanol medium. The specific textural and chemical characteristics of prepared carbon samples were identified by Raman, XRD, XPS, NH;-TPD, FT-IR and nitrogen physisorption. Various parameters such as ethanol/water volume ratio, Na Cl addition, reaction temperature, and catalyst dosage played a great role in ethyl levulinate production. A desirable ethyl levulinate yield of 58.0 mol% with a highest ROF（rate of ethyl levulinate formation per gram of catalyst per hour） value of 2148.3 μmol/(g;·h) was achieved at 468 K over FeCl;modified carbon catalyst with respect to fructose conversion. The recycling experiments revealed that the sulfonated carbon catalysts exhibited relatively satisfied activity and stability.展开更多
文摘The molecular sieves supported TiO 2/SO 2- 4 catalyst was prepared by the liquid phase precipitation,then its preparation conditions were investigated in detail.The results indicated that the pH value of solution was adjusted to 1.8,the mass ratio of TiO 2 to molecular sieves was 0.13∶100,the water in the system must be evaporated slowly at 90℃.And the best active temperature of catalyst was 50℃.The factors that had influence on the esterification of levulinic acid with alcohol were also discussed,the optimum reaction conditions were 5∶100(mass ratio) of catalyst to acid,5∶6(volume ratio) of alcohol to acid,oil bath temperature being kept at 110℃ and suitable reaction time being 1.5h.Under such conditions,the ester yield could be as high as 96.5%.
文摘The synthesis of carbon-based, heterogeneous sulphonic catalysts for the production of levulinate esters. Hydrothermal treatment at moderated temperatures was employed to generate highly functional carbonaceous materials, referred to as hydrothermal carbons (HTCs), from both glucose, cellulose and rye straw. The products were sulfonated to generate solid acid-catalysts. Characterisation of the as-synthesised materials as well as catalyst activity tests were performed. SEM images indicate the micrometre-sized particles present in both HTCs were largely unaffected by sulfonation, although cellulose-derived HTC displayed signs of inadequate hydrolysis. FT-IR spectroscopy and elemental analysis confirmed successful incorporation of sulphonic groups. 13C solid state NMR, in addition to TGA, elucidated the carbons’ structural composition and supported the common-ly-proposed hydrothermal carbonisation mechanism. Finally, the catalysts were tested via levulinic acid-ethanol esterification and gave high conversion and ester-selectivities (> 90%).
基金supported by the Natural Science Foundation of Guangdong Province, China (2014A030310386, 2016A030313173, 2015A030312007)the National Natural Science Foundation of China (21472189)+2 种基金the National Basic Research Program of China (973 Program, 2012CB215304)Science and Technology Planning Project of Guangdong Province, China (2015A010106010)Open fund of Key Laboratory of Renewable Energy, Chinese Academy of Sciences (y507ja1001)
文摘A series of metal salt-modified carbon catalysts had been prepared to study the selective transformation of various carbohydrates into ethyl levulinate in an ethanol medium. The specific textural and chemical characteristics of prepared carbon samples were identified by Raman, XRD, XPS, NH;-TPD, FT-IR and nitrogen physisorption. Various parameters such as ethanol/water volume ratio, Na Cl addition, reaction temperature, and catalyst dosage played a great role in ethyl levulinate production. A desirable ethyl levulinate yield of 58.0 mol% with a highest ROF（rate of ethyl levulinate formation per gram of catalyst per hour） value of 2148.3 μmol/(g;·h) was achieved at 468 K over FeCl;modified carbon catalyst with respect to fructose conversion. The recycling experiments revealed that the sulfonated carbon catalysts exhibited relatively satisfied activity and stability.
