Shenmu(SM)subbituminous coal without caking property was treated by low-temperature rapid pyrolysis(LTRP)to modify its caking and coking properties.The treated samples were characterized by Fourier transform infrared ...Shenmu(SM)subbituminous coal without caking property was treated by low-temperature rapid pyrolysis(LTRP)to modify its caking and coking properties.The treated samples were characterized by Fourier transform infrared spectrometry,vitrinite reflectance,and X-ray diffraction to determine the modification mechanism.Moreover,caking index(G)and coking indices(mechanical strength,coke reactivity,and coke strength after reaction)were employed to evaluate caking and coking properties,respectively.The results showed that SM coal was gradually upgraded with increasing processing temperature.Furthermore,the G values for the treated samples were significantly higher than that for SM coal,and G reached the maximum value at 450℃,implying the modification of caking property and the existence of an optimum temperature(450℃).Additionally,laboratory coking determinations showed that LTRP increased the mechanical strength of coke and coke strength after reaction and decreased coke reactivity when the treated coals were used in the coal blends instead of raw SM coal.Overall,LTRP treatment is effective to improve the caking and coking properties of SM coal.A mechanism was proposed for the modification.Suitable upgrading degree with suitable molecular masses and some releasable hydrogen-rich donor species present within the coal,which dominate the development of caking property,is important.展开更多
Coal has a highly complex chemical structure,similar to polymers,coal is a macromolecular structure composed of a large number of“similar compounds”,which is called the basic structural unit.Understanding coal struc...Coal has a highly complex chemical structure,similar to polymers,coal is a macromolecular structure composed of a large number of“similar compounds”,which is called the basic structural unit.Understanding coal structure is the basis of its transformation and utilization.Shendong(SD)coal was analyzed by FTIR,XRD,XPS,and NMR.The results show that SD coal normalized structure formula is C_(100)H_(68.5)O_(35.7)N_(1.2)S_(0.2)and the average number of aromatic rings is 1.98.-CH_(2)-content accounts for about 82%in aliphatic CeH region,and the ratio of ether bond CeO,aromatic ether C-O and C=O is about 2:1:11 in oxygen-containing functional group region.The d_(002),L_(C),L_(a)and N_(C)of S_(D)coal microcrystalline structure parameters are 0.1832 nm,1.4688 nm,2.0852 nm and 9.017,respectively.Aromatic carbon and aliphatic carbon ratios of SD coal are 55.67%and 29.97%,aromatic cluster size and average methylene chain length are 0.224 and 1.817.Based on these structural parameters,molecular model of SD coal was constructed with^(13)C SSNMR experimental spectra as a reference.The model was constructed with an atom composition of C_(214)H_(214)O_(49)N_(2)S.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
基金The authors are grateful to the National Natural Science Foundation of China(No.21776002)Natural Science Foundation of Anhui Provincial Education Department(Nos.KJ2016A097 and KJ2017A056)+1 种基金Innovation Project of Overseas People of Anhui Province,Student Research Training Program of Anhui Province(201810360190)Youth Natural Science Foundation of Anhui University of Technology(No.QZ201806)for financial support.
文摘Shenmu(SM)subbituminous coal without caking property was treated by low-temperature rapid pyrolysis(LTRP)to modify its caking and coking properties.The treated samples were characterized by Fourier transform infrared spectrometry,vitrinite reflectance,and X-ray diffraction to determine the modification mechanism.Moreover,caking index(G)and coking indices(mechanical strength,coke reactivity,and coke strength after reaction)were employed to evaluate caking and coking properties,respectively.The results showed that SM coal was gradually upgraded with increasing processing temperature.Furthermore,the G values for the treated samples were significantly higher than that for SM coal,and G reached the maximum value at 450℃,implying the modification of caking property and the existence of an optimum temperature(450℃).Additionally,laboratory coking determinations showed that LTRP increased the mechanical strength of coke and coke strength after reaction and decreased coke reactivity when the treated coals were used in the coal blends instead of raw SM coal.Overall,LTRP treatment is effective to improve the caking and coking properties of SM coal.A mechanism was proposed for the modification.Suitable upgrading degree with suitable molecular masses and some releasable hydrogen-rich donor species present within the coal,which dominate the development of caking property,is important.
基金financed by the Department of education of Gansu Province:Young Doctor Fund Project(2022QB-029)the Fundamental Research Funds for the Central Universities(31920240125-06,31920240059)+1 种基金the Scientific Research Project of Introducing Talents of Northwest Minzu University(xbmuyjrc202215,xbmuyjrc202216)the National Natural Science Foundation of China(22178289).
文摘Coal has a highly complex chemical structure,similar to polymers,coal is a macromolecular structure composed of a large number of“similar compounds”,which is called the basic structural unit.Understanding coal structure is the basis of its transformation and utilization.Shendong(SD)coal was analyzed by FTIR,XRD,XPS,and NMR.The results show that SD coal normalized structure formula is C_(100)H_(68.5)O_(35.7)N_(1.2)S_(0.2)and the average number of aromatic rings is 1.98.-CH_(2)-content accounts for about 82%in aliphatic CeH region,and the ratio of ether bond CeO,aromatic ether C-O and C=O is about 2:1:11 in oxygen-containing functional group region.The d_(002),L_(C),L_(a)and N_(C)of S_(D)coal microcrystalline structure parameters are 0.1832 nm,1.4688 nm,2.0852 nm and 9.017,respectively.Aromatic carbon and aliphatic carbon ratios of SD coal are 55.67%and 29.97%,aromatic cluster size and average methylene chain length are 0.224 and 1.817.Based on these structural parameters,molecular model of SD coal was constructed with^(13)C SSNMR experimental spectra as a reference.The model was constructed with an atom composition of C_(214)H_(214)O_(49)N_(2)S.
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℃.
