The conversion of lignocellulose to value-added products is normally focused on fuel production;however,large-scale biorefineries require a cost-effective pretreatment process that can effectively fractionate the thre...The conversion of lignocellulose to value-added products is normally focused on fuel production;however,large-scale biorefineries require a cost-effective pretreatment process that can effectively fractionate the three main constituents of lignocellulose for the production of chemicals,fuels,and materials.In this study,a hemicellulosic biopolymer from poplar was fractionated by a mild organosolv process and the effects of various chemicals(sodium hydroxide,triethylamine,and formic acid)and alcohols on the fractionation efficiency and structural variation of hemicellulose were examined.Comparative studies indicated that an acidic catalyst decreased the purity of hemicelluloses by partial degradation of cellulose,and the core of the hemicellulosic biomacromolecule could be released and dissolved under alkaline conditions with 5.8%~19.0%yields.In addition,the use of alcohol with longer alkyl chains facilitated the release of the hemicellulosic biomacromolecule by partially cleaving the ether bonds in the lignincarbohydrate complex(LCC);this is probably due to steric hindrance.The thermal degradation behavior showed that complete pyrolysis was easily achieved for the hemicellulosic polymer with minimal branches irrespective of its molecular weight.展开更多
Cellulose is a biodegradable and renewable natural material that it is naturally resistant to breaking and modification. Moreover, the crystalline structure of cellulose is a major factor restricting its industrial ut...Cellulose is a biodegradable and renewable natural material that it is naturally resistant to breaking and modification. Moreover, the crystalline structure of cellulose is a major factor restricting its industrial utilization. In this study, cellulose polymorphs were prepared from natural cellulose, and their solvability and thermal response were investigated. Using liquid- and solid-state NMR signals, the distinct types and dissolving states of cellulose polymorphs were identified. The thermal behavior of the polymorphic forms of cellulose-d was also evaluated, and cellulose Ⅱ exhibited the poorest thermal stability and a unique exothermic reaction.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities (2017TP13)the National Key R&D Program of China (2016YFD0600803)+2 种基金2018 National Student Research Training Program (201710022033)the Innovation Program of College of Materials Science and Technologysupported by the 2017 the international Clean Energy Talent program (No.201702660054)
文摘The conversion of lignocellulose to value-added products is normally focused on fuel production;however,large-scale biorefineries require a cost-effective pretreatment process that can effectively fractionate the three main constituents of lignocellulose for the production of chemicals,fuels,and materials.In this study,a hemicellulosic biopolymer from poplar was fractionated by a mild organosolv process and the effects of various chemicals(sodium hydroxide,triethylamine,and formic acid)and alcohols on the fractionation efficiency and structural variation of hemicellulose were examined.Comparative studies indicated that an acidic catalyst decreased the purity of hemicelluloses by partial degradation of cellulose,and the core of the hemicellulosic biomacromolecule could be released and dissolved under alkaline conditions with 5.8%~19.0%yields.In addition,the use of alcohol with longer alkyl chains facilitated the release of the hemicellulosic biomacromolecule by partially cleaving the ether bonds in the lignincarbohydrate complex(LCC);this is probably due to steric hindrance.The thermal degradation behavior showed that complete pyrolysis was easily achieved for the hemicellulosic polymer with minimal branches irrespective of its molecular weight.
基金the National Natural Science Foundation of China (Grant No. 31770622)the Beijing Natural Science Foundation (Grant No. 6174046)+1 种基金the Fundamental Research Funds for the Central Universities (No. 2017PT13)the China Scholarship Council (International Clean Energy Talent Programme (iCET), Grant No. 201702660054).
文摘Cellulose is a biodegradable and renewable natural material that it is naturally resistant to breaking and modification. Moreover, the crystalline structure of cellulose is a major factor restricting its industrial utilization. In this study, cellulose polymorphs were prepared from natural cellulose, and their solvability and thermal response were investigated. Using liquid- and solid-state NMR signals, the distinct types and dissolving states of cellulose polymorphs were identified. The thermal behavior of the polymorphic forms of cellulose-d was also evaluated, and cellulose Ⅱ exhibited the poorest thermal stability and a unique exothermic reaction.
