Tars from two Mongolian coals (Tavan Tolgoi and Baganuur) produced by simple distillation have been characterized using size exclusion chromatography (SEC) with elution in both 1-methyl-2-pyrrolidinone (NMP) and a mix...Tars from two Mongolian coals (Tavan Tolgoi and Baganuur) produced by simple distillation have been characterized using size exclusion chromatography (SEC) with elution in both 1-methyl-2-pyrrolidinone (NMP) and a mixed solvent (NMP and chloroform), UV-fluorescence in chloroform and NMP, gas chromatography (GC), mass spectrometry (GC-MS, probe-MS and LD-MS with thin layer chromatography) and infra-red spectroscopy. The SEC chromatograms using NMP and the solvent mixture NMP: chloroform indicates that similar conclusions can be drawn from using either eluent. The synchronous UV-fluorescence spectra were shifted to longer wavelengths in chloroform solution than in NMP and chloroform may be the better solvent for these tars prepared without extensive secondary thermal treatment. Infra-red spectra indicated differences between the two coal tars that reflected their different ranks, with more oxygenate groups in the lower rank Baganuur coal. Mass spectrometry (GC-MS and probe-MS) of both coal tars confirmed the presence of aliphatic components as well as aromatics and the relatively extensive alkylation of aromatics. Molecular mass ranges indicated for Baganuur tar by SEC compared well with the mass range by LD-MS although the LD-MS extended to higher mass values. The high mass fractions of the tars were revealed by fractionation by thin layer chromatography with the relevant sections of the developed plates inserted directly into the mass spectrometer;laser desorption was directly from the surface of the plate. LD-MS of the unfractionated samples failed to detect the high mass components because of mass discrimination effects. The high mass components were carried over in the distillation by mass transfer of vapours into the condenser.展开更多
Low temperature pyrolysis behavior of four low-rank coals from the biggest deposits of Mongolia were studied using a fixed-bed reactor and Gray-King retort.The coal samples and resultant chars were analyzed using Four...Low temperature pyrolysis behavior of four low-rank coals from the biggest deposits of Mongolia were studied using a fixed-bed reactor and Gray-King retort.The coal samples and resultant chars were analyzed using Fourier transform infrared spectroscopy(FTIR),^(13)C nuclear magnetic resonance(^(13)C NMR)to explore the structure changes and thermogravimetric analyzer coupled with mass spectrometry(TG-MS)was used to investigate the pyrolysis reactivity of coal during thermal decomposition process.The results showed that the aliphatic structure in coal was significantly reduced and the carboxyl groups almost completely decomposed during pyrolysis process at 600℃.The tar yield of Gray-king test is higher than that obtained from the fixed-bed reactor.The gaseous evolution measured by TG-MS during pyrolysis showed that the maximum peaks of evolution of CH_(4),H_(2),C_(2)H_(2),C_(2)H_(5),CO,and CO_(2) gases were well corresponded to the maximum rate of weight loss in the range 428-445℃.展开更多
文摘Tars from two Mongolian coals (Tavan Tolgoi and Baganuur) produced by simple distillation have been characterized using size exclusion chromatography (SEC) with elution in both 1-methyl-2-pyrrolidinone (NMP) and a mixed solvent (NMP and chloroform), UV-fluorescence in chloroform and NMP, gas chromatography (GC), mass spectrometry (GC-MS, probe-MS and LD-MS with thin layer chromatography) and infra-red spectroscopy. The SEC chromatograms using NMP and the solvent mixture NMP: chloroform indicates that similar conclusions can be drawn from using either eluent. The synchronous UV-fluorescence spectra were shifted to longer wavelengths in chloroform solution than in NMP and chloroform may be the better solvent for these tars prepared without extensive secondary thermal treatment. Infra-red spectra indicated differences between the two coal tars that reflected their different ranks, with more oxygenate groups in the lower rank Baganuur coal. Mass spectrometry (GC-MS and probe-MS) of both coal tars confirmed the presence of aliphatic components as well as aromatics and the relatively extensive alkylation of aromatics. Molecular mass ranges indicated for Baganuur tar by SEC compared well with the mass range by LD-MS although the LD-MS extended to higher mass values. The high mass fractions of the tars were revealed by fractionation by thin layer chromatography with the relevant sections of the developed plates inserted directly into the mass spectrometer;laser desorption was directly from the surface of the plate. LD-MS of the unfractionated samples failed to detect the high mass components because of mass discrimination effects. The high mass components were carried over in the distillation by mass transfer of vapours into the condenser.
基金financially supported by Bureau of International Cooperation,Chinese Academy of Sciences(Grant No.122214KYSB20170020)the President’s International Fellowship Initiative of Chinese Academy of Sciences(Grant No.2018VSB0003)for financial support of her research stay at State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan PR China.
文摘Low temperature pyrolysis behavior of four low-rank coals from the biggest deposits of Mongolia were studied using a fixed-bed reactor and Gray-King retort.The coal samples and resultant chars were analyzed using Fourier transform infrared spectroscopy(FTIR),^(13)C nuclear magnetic resonance(^(13)C NMR)to explore the structure changes and thermogravimetric analyzer coupled with mass spectrometry(TG-MS)was used to investigate the pyrolysis reactivity of coal during thermal decomposition process.The results showed that the aliphatic structure in coal was significantly reduced and the carboxyl groups almost completely decomposed during pyrolysis process at 600℃.The tar yield of Gray-king test is higher than that obtained from the fixed-bed reactor.The gaseous evolution measured by TG-MS during pyrolysis showed that the maximum peaks of evolution of CH_(4),H_(2),C_(2)H_(2),C_(2)H_(5),CO,and CO_(2) gases were well corresponded to the maximum rate of weight loss in the range 428-445℃.
