We examined wood liquefaction using phenol and mixed acid catalysts with microwave heating, and compared that with similar processes that use oil bath heating. The reaction time for microwave heating to achieve a resi...We examined wood liquefaction using phenol and mixed acid catalysts with microwave heating, and compared that with similar processes that use oil bath heating. The reaction time for microwave heating to achieve a residue content was one sixth, one eighteenth, and one twenty-fourth of that from oil bath heating, respectively, for phenol to wood （P/W） ratios of 2.5/1, 2/1 and 1.5/1. A low P/W ratio tended to result in carbonization of liquefied wood due to an insufficient amount of phenol and localized microwave superheating. Fourier transform infrared spectroscopic （FTIR） evaluation of the liquefied residue, showed that the liquefaction rates of wood com- ponents differed. Hemicellulose was most susceptible to liquefaction, crystalline cellulose was most recalcitrant, and guaiacyl units the most prone to re-condensation. From FTIR, the chemical components and substitution patterns of bonded phenol were similar for both methods.展开更多
The effect of etching environment(opened or closed)on the synthesis and electrochemical properties of V_(2)C MXene was studied.V_(2)C MXene samples were synthesized by selectively etching of V2AlC at 90℃in two differ...The effect of etching environment(opened or closed)on the synthesis and electrochemical properties of V_(2)C MXene was studied.V_(2)C MXene samples were synthesized by selectively etching of V2AlC at 90℃in two different environments:opened environment(OE)in oil bath pans under atmosphere pressure and closed environment(CE)in hydrothermal reaction kettles under higher pressures.In OE,only NaF(sodium fluoride)+HCl(hydrochloric acid)etching solution can be used to synthesize highly pure V_(2)C MXene.However,in CE,both LiF(lithium fluoride)+HCl and NaF+HCl etchant can be used to prepare V_(2)C MXene.Moreover,the V_(2)C MXene samples made in CE had higher purity and better-layered structure than those made in OE.Although the purity of V_(2)C obtained by LiF+HCl is lower than that of V_(2)C obtained using NaF+HCl,it shows better electrochemical performance as anodes of lithium-ion batteries(LIBs).Therefore,etching in CE is a better method for preparing highly pure V_(2)C MXene,which provides a reference for expanding the synthesis methods of V_(2)C with better electrochemical properties.展开更多
基金financially supported by the ‘‘948Project’’ of State Forestry Administration(2012-4-28)
文摘We examined wood liquefaction using phenol and mixed acid catalysts with microwave heating, and compared that with similar processes that use oil bath heating. The reaction time for microwave heating to achieve a residue content was one sixth, one eighteenth, and one twenty-fourth of that from oil bath heating, respectively, for phenol to wood （P/W） ratios of 2.5/1, 2/1 and 1.5/1. A low P/W ratio tended to result in carbonization of liquefied wood due to an insufficient amount of phenol and localized microwave superheating. Fourier transform infrared spectroscopic （FTIR） evaluation of the liquefied residue, showed that the liquefaction rates of wood com- ponents differed. Hemicellulose was most susceptible to liquefaction, crystalline cellulose was most recalcitrant, and guaiacyl units the most prone to re-condensation. From FTIR, the chemical components and substitution patterns of bonded phenol were similar for both methods.
基金supported by the National Natural Science Foundation of China(51772077)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province(19IRTSTHN027)+5 种基金the Fundamental Research Funds for the Universities of Henan Province(NSFRF200101)the China Postdoctoral Science Foundation(2019M652537)the Henan Postdoctoral Foundation(19030065)the Henan Province Key Science and Tech-nology Research Projects(202102310628)the Foundation of Henan Educational Committee(20B430006)the Doctoral Foundation of Henan Polytechnic University(B2019-41).
文摘The effect of etching environment(opened or closed)on the synthesis and electrochemical properties of V_(2)C MXene was studied.V_(2)C MXene samples were synthesized by selectively etching of V2AlC at 90℃in two different environments:opened environment(OE)in oil bath pans under atmosphere pressure and closed environment(CE)in hydrothermal reaction kettles under higher pressures.In OE,only NaF(sodium fluoride)+HCl(hydrochloric acid)etching solution can be used to synthesize highly pure V_(2)C MXene.However,in CE,both LiF(lithium fluoride)+HCl and NaF+HCl etchant can be used to prepare V_(2)C MXene.Moreover,the V_(2)C MXene samples made in CE had higher purity and better-layered structure than those made in OE.Although the purity of V_(2)C obtained by LiF+HCl is lower than that of V_(2)C obtained using NaF+HCl,it shows better electrochemical performance as anodes of lithium-ion batteries(LIBs).Therefore,etching in CE is a better method for preparing highly pure V_(2)C MXene,which provides a reference for expanding the synthesis methods of V_(2)C with better electrochemical properties.
