In this work,a novel alcohol alkali hydrolysis method was explored for the preparation of terephthalic acid(TPA)from waste polyethylene terephthalate(PET).First,a series of single factor experiments on the depolymeriz...In this work,a novel alcohol alkali hydrolysis method was explored for the preparation of terephthalic acid(TPA)from waste polyethylene terephthalate(PET).First,a series of single factor experiments on the depolymerization rate of waste PET bottles and the yield of TPA were conducted to determine the optimized experimental conditions,in terms of reaction time,reaction temperature,dosage of ethylene glycol and sodium bicarbonate,amount of distilled water and stirring rate.Then IR spectra and elemental analysis were carried out for the characterization of obtained product.Under optimal experimental conditions,over 98%PET can be depolymerized into the target product(TPA)and the purity and yield of TPA are over 97%and 94%,respectively.Both the experimental and analytical results support a feasible process for the preparation of TPA from waste PET.It is expected that this alcohol alkali hydrolysis method can promise an effective way for the sustainable recycling of waste PET.展开更多
Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar(ET-HR)by a two-step method of bromination and subsequent dehydrobromination/polycondensation.The ...Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar(ET-HR)by a two-step method of bromination and subsequent dehydrobromination/polycondensation.The ET-HR was first brominated at 30 or 200℃,and then heat-treated at 350℃to enable the dehydrobromination/polycondensation reactions.GC/MS and LDI TOF/MS spectra indicated that the ET-HR was mainly composed of compounds containing 3-to 6-ring aromatic species with a considerable aliphatic chain content.Compared with thermal condensation alone,such a two-step method increased the softening point of the pitches from 152 to 264℃with a yield in the range of 62 wt.%-67 wt.%and a coking value in the range of 57 wt.%-77 wt.%,depending on the bromination temperature and the bromine content.Structural characterization of the as-prepared pitches by elemental analysis,1H NMR,FT-IR and LDI-TOF/MS showed increased aromatization and polymerization of the precursor during the dehydrobrominatio/polycondensation.All the homogeneous isotropic pitches showed an ability to transform into an anisotropic texture after coking at 800℃.展开更多
Ethylene carbonate(EC) liquid and its vapor-liquid interface were investigated using a combination of molecular dynamics(MD)simulation and vibrational IR, Raman and sum frequency generation(SFG)spectroscopies. The MD ...Ethylene carbonate(EC) liquid and its vapor-liquid interface were investigated using a combination of molecular dynamics(MD)simulation and vibrational IR, Raman and sum frequency generation(SFG)spectroscopies. The MD simulation was performed with a flexible and polarizable model of the EC molecule newly developed for the computation of vibrational spectra. The internal vibration of the model was described on the basis of the harmonic couplings of vibrational modes, including the anharmonicity and Fermi resonance coupling of C=O stretching. The polarizable model was represented by the charge response kernel(CRK),which is based on ab initio molecular orbital calculations and can be readily applied to other systems. The flexible and polarizable model can also accurately reproduce the structural and thermodynamic properties of EC liquid. Meanwhile, a comprehensive set of vibrational spectra of EC liquid, including the IR and Raman spectra of the bulk liquid as well as the SFG spectra of the liquid interface, were experimentally measured and reported. The set of experimental vibrational spectra provided valuable information for validating the model, and the MD simulation using the model comprehensively elucidates the observed vibrational IR, Raman, and SFG spectra of EC liquid. Further MD analysis of the interface region revealed that EC molecules tend to orientate themselves with the C=O bond parallel to the interface. The MD simulation explains the positive Im[χ^((2))](ssp) band of the C=O stretching region in the SFG spectrum in terms of the preferential orientation of EC molecules at the interface. This work also elucidates the distinct lineshapes of the C=O stretching band in the IR, Raman, and SFG spectra. The lineshapes of the C=O band are split by the Fermi resonance of the C=O fundamental and the overtone of skeletal stretching. The Fermi resonance of C=O stretching was fully analyzed using the empirical potential parameter shift analysis(EPSA) method. The apparently different lineshapes of the C=O stretching band in the IR, Raman, and SFG spectra were attributed to the frequency shift of the C=O fundamental in different solvation environments in the bulk liquid and at the interface. This work proposes a systematic procedure for investigating the interface structure and SFG spectra, including general modeling procedure based on ab initio calculations, validation of the model using available experimental data, and simultaneous analysis of molecular orientation and SFG spectra through MD trajectories. The proposed procedure provides microscopic information on the EC interface in this study, and can be further applied to investigate other interface systems, such as liquid-liquid and solid-liquid interfaces.展开更多
Rice sheath blight is one of the main diseases in rice production in China,which can make rice unable to absorb and utilize nutrients,and has a serious impact on rice yield and quality.In this study,exogenous ethylene...Rice sheath blight is one of the main diseases in rice production in China,which can make rice unable to absorb and utilize nutrients,and has a serious impact on rice yield and quality.In this study,exogenous ethylene was used to induce rice resistance against rice sheath blight,aiming at exploring a new environment-friendly control method of rice sheath blight.The results showed that within a range of certain concentrations,ethylene had no significant effects on mycelium growth,but it could induce resistance to sheath blight in rice.The optimum concentration was 0.2 mmol•L^(-1) and the relative control was 86.17%.It was found that ethylene could effectively increase the activities of peroxidase(POD),phenylalanine ammonia-lyase(PAL),β-1,3-glucanase and reduce the contents of malondialdehyde(MDA),which could enhance the resistance of rice against Rhizoctonia solani.In addition,qRT-PCR detected the expressions of rice defense genes,which indicated that the expressions of the POX,PAL and OsPR1b genes were up-regulated.展开更多
The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nick...The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.展开更多
基金Project(2016TP1007)supported by the Hunan Provincial Science and Technology Plan,China
文摘In this work,a novel alcohol alkali hydrolysis method was explored for the preparation of terephthalic acid(TPA)from waste polyethylene terephthalate(PET).First,a series of single factor experiments on the depolymerization rate of waste PET bottles and the yield of TPA were conducted to determine the optimized experimental conditions,in terms of reaction time,reaction temperature,dosage of ethylene glycol and sodium bicarbonate,amount of distilled water and stirring rate.Then IR spectra and elemental analysis were carried out for the characterization of obtained product.Under optimal experimental conditions,over 98%PET can be depolymerized into the target product(TPA)and the purity and yield of TPA are over 97%and 94%,respectively.Both the experimental and analytical results support a feasible process for the preparation of TPA from waste PET.It is expected that this alcohol alkali hydrolysis method can promise an effective way for the sustainable recycling of waste PET.
文摘Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar(ET-HR)by a two-step method of bromination and subsequent dehydrobromination/polycondensation.The ET-HR was first brominated at 30 or 200℃,and then heat-treated at 350℃to enable the dehydrobromination/polycondensation reactions.GC/MS and LDI TOF/MS spectra indicated that the ET-HR was mainly composed of compounds containing 3-to 6-ring aromatic species with a considerable aliphatic chain content.Compared with thermal condensation alone,such a two-step method increased the softening point of the pitches from 152 to 264℃with a yield in the range of 62 wt.%-67 wt.%and a coking value in the range of 57 wt.%-77 wt.%,depending on the bromination temperature and the bromine content.Structural characterization of the as-prepared pitches by elemental analysis,1H NMR,FT-IR and LDI-TOF/MS showed increased aromatization and polymerization of the precursor during the dehydrobrominatio/polycondensation.All the homogeneous isotropic pitches showed an ability to transform into an anisotropic texture after coking at 800℃.
基金supported by Elements Strategy Initiative for Catalysts and Batteries,Kyoto University,Cooperative Research Program of Institute for Catalysis,Hokkaido University,Japan and the Grants-in-Aids(JP25104003,JP26288003)by the Japan Society for the Promotion of Science(JSPS)and Ministry of Education,Culture,Sports and Technology(MEXT),Japan
文摘Ethylene carbonate(EC) liquid and its vapor-liquid interface were investigated using a combination of molecular dynamics(MD)simulation and vibrational IR, Raman and sum frequency generation(SFG)spectroscopies. The MD simulation was performed with a flexible and polarizable model of the EC molecule newly developed for the computation of vibrational spectra. The internal vibration of the model was described on the basis of the harmonic couplings of vibrational modes, including the anharmonicity and Fermi resonance coupling of C=O stretching. The polarizable model was represented by the charge response kernel(CRK),which is based on ab initio molecular orbital calculations and can be readily applied to other systems. The flexible and polarizable model can also accurately reproduce the structural and thermodynamic properties of EC liquid. Meanwhile, a comprehensive set of vibrational spectra of EC liquid, including the IR and Raman spectra of the bulk liquid as well as the SFG spectra of the liquid interface, were experimentally measured and reported. The set of experimental vibrational spectra provided valuable information for validating the model, and the MD simulation using the model comprehensively elucidates the observed vibrational IR, Raman, and SFG spectra of EC liquid. Further MD analysis of the interface region revealed that EC molecules tend to orientate themselves with the C=O bond parallel to the interface. The MD simulation explains the positive Im[χ^((2))](ssp) band of the C=O stretching region in the SFG spectrum in terms of the preferential orientation of EC molecules at the interface. This work also elucidates the distinct lineshapes of the C=O stretching band in the IR, Raman, and SFG spectra. The lineshapes of the C=O band are split by the Fermi resonance of the C=O fundamental and the overtone of skeletal stretching. The Fermi resonance of C=O stretching was fully analyzed using the empirical potential parameter shift analysis(EPSA) method. The apparently different lineshapes of the C=O stretching band in the IR, Raman, and SFG spectra were attributed to the frequency shift of the C=O fundamental in different solvation environments in the bulk liquid and at the interface. This work proposes a systematic procedure for investigating the interface structure and SFG spectra, including general modeling procedure based on ab initio calculations, validation of the model using available experimental data, and simultaneous analysis of molecular orientation and SFG spectra through MD trajectories. The proposed procedure provides microscopic information on the EC interface in this study, and can be further applied to investigate other interface systems, such as liquid-liquid and solid-liquid interfaces.
基金Supported by the Natural Science Foundation of Heilongjiang Province(C2017032)Heilongjiang Province Applied Technology Research and Development Program(GA19B104)National Key Research and Development Program(2018YFD0300105)。
文摘Rice sheath blight is one of the main diseases in rice production in China,which can make rice unable to absorb and utilize nutrients,and has a serious impact on rice yield and quality.In this study,exogenous ethylene was used to induce rice resistance against rice sheath blight,aiming at exploring a new environment-friendly control method of rice sheath blight.The results showed that within a range of certain concentrations,ethylene had no significant effects on mycelium growth,but it could induce resistance to sheath blight in rice.The optimum concentration was 0.2 mmol•L^(-1) and the relative control was 86.17%.It was found that ethylene could effectively increase the activities of peroxidase(POD),phenylalanine ammonia-lyase(PAL),β-1,3-glucanase and reduce the contents of malondialdehyde(MDA),which could enhance the resistance of rice against Rhizoctonia solani.In addition,qRT-PCR detected the expressions of rice defense genes,which indicated that the expressions of the POX,PAL and OsPR1b genes were up-regulated.
基金supported by the National Key R&D Program of China(2021YFA1501700)Fundamental Research Funds for the Central Universities(WK9990000142).
文摘The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.
