The increase in the residue content resulting from polycondensation would be adverse to the utilization of lignocellulose and to the quality of products obtained from liquefied lignocellulosic material.The yield of th...The increase in the residue content resulting from polycondensation would be adverse to the utilization of lignocellulose and to the quality of products obtained from liquefied lignocellulosic material.The yield of the residue formed from liquefaction and the mechanism of polycondensation were reported mainly by Lin,Yamada and Kobayashi.The major products of cellulosic liquefaction are levulinic acid and hydroxymethylfurfural（HMF） derivatives under polyhydric alcohols and phenolated compounds under phenols.The cleavage of the β-O-4 bonds is the major reaction pathway of lignin liquefaction under various liquefying reagents regardless of whether they contain acid catalysts or not.The break up compounds by decomposition are polymerized to substances with high molecular weight by polycondensation in lignocellulosic liquefaction.The molecular weight of condensed residues increases almost linearly as a function of liquefaction time at the later stage of lignocellulosic liquefaction.The longer the time required,the greater the content of new residue generated by polycondensation during the entire process of liquefaction.We conclude that the condensed residues may stem from the interaction of degraded lignin and cellulose components in wood or from the products of two major components reacting with liquefying reagents.展开更多
The thermal behavior, mechanism and kinetic parameters of the exothermic decomposition reaction of 3,3-bis(azidomethyl)oxetane/tetrahydrofuran (BAMO/THF) copolymer in a temperature-programmed mode have been investigat...The thermal behavior, mechanism and kinetic parameters of the exothermic decomposition reaction of 3,3-bis(azidomethyl)oxetane/tetrahydrofuran (BAMO/THF) copolymer in a temperature-programmed mode have been investigated by means of DSC, TG-DTG, fast and lower thermolysis/FTIR and TG-MS. The reaction mecha-nism was proposed. The apparent activation energy and pre-exponential constant of exothermic decomposition re-action of the compound at 0.1 MPa are 167.04 kJ昺ol-1 and 1014.41 s-1, respectively. The corresponding critical temperatures of thermal explosion obtained from the onset temperature Te and the peak temperature Tp are 223.20 and 245.78 ℃, respectively. The kinetic equation of the exothermic decomposition process of BAMO/THF at 0.1 MPa could be expressed as: ()[]24315.1922.009×10/d10ln1edTTaa-=--展开更多
基金supported by the Forestry Public Special Scientific Research (No. 201004057)
文摘The increase in the residue content resulting from polycondensation would be adverse to the utilization of lignocellulose and to the quality of products obtained from liquefied lignocellulosic material.The yield of the residue formed from liquefaction and the mechanism of polycondensation were reported mainly by Lin,Yamada and Kobayashi.The major products of cellulosic liquefaction are levulinic acid and hydroxymethylfurfural（HMF） derivatives under polyhydric alcohols and phenolated compounds under phenols.The cleavage of the β-O-4 bonds is the major reaction pathway of lignin liquefaction under various liquefying reagents regardless of whether they contain acid catalysts or not.The break up compounds by decomposition are polymerized to substances with high molecular weight by polycondensation in lignocellulosic liquefaction.The molecular weight of condensed residues increases almost linearly as a function of liquefaction time at the later stage of lignocellulosic liquefaction.The longer the time required,the greater the content of new residue generated by polycondensation during the entire process of liquefaction.We conclude that the condensed residues may stem from the interaction of degraded lignin and cellulose components in wood or from the products of two major components reacting with liquefying reagents.
基金Project supported by the Science and Technology Foundation of the National Defense Key Laboratory of Propellant and Explosive Combustion of China (No. 51455030101ZS3505).
文摘The thermal behavior, mechanism and kinetic parameters of the exothermic decomposition reaction of 3,3-bis(azidomethyl)oxetane/tetrahydrofuran (BAMO/THF) copolymer in a temperature-programmed mode have been investigated by means of DSC, TG-DTG, fast and lower thermolysis/FTIR and TG-MS. The reaction mecha-nism was proposed. The apparent activation energy and pre-exponential constant of exothermic decomposition re-action of the compound at 0.1 MPa are 167.04 kJ昺ol-1 and 1014.41 s-1, respectively. The corresponding critical temperatures of thermal explosion obtained from the onset temperature Te and the peak temperature Tp are 223.20 and 245.78 ℃, respectively. The kinetic equation of the exothermic decomposition process of BAMO/THF at 0.1 MPa could be expressed as: ()[]24315.1922.009×10/d10ln1edTTaa-=--
