Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH4 H2O, CO, CO2, etc., during the coal pyrolysis is an important bu...Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH4 H2O, CO, CO2, etc., during the coal pyrolysis is an important but confusing subject. In this paper, quadrupole mass spectronletry, gas chromatography, and ^l3C nuclear magnetic resonance are applied to real-time monitoring the formations of volatile products, off-line quantitative determination of the total products from the pyrolysis of a sub-bituminous coal (SC), and the changes of diverse substitents in the SC along with coke foamation, respectively. These measurements are also performed for the pyrolysis of a caking coal to contrast SC. The qualitative and quantitative data reveal that, during coal pyrolysis, the functional groups related with the formation of CO, i.e., ether, carbonyl, and anhydride, can directly gen erate CO via bond breaking, or take a detour of the formation of other intermediates via condensation and recombination firstly. Moreover, the formations of CO2 and CH4 are related to the direct removal of -COO- and -CH3,respectively.展开更多
Inherent metallic species retained by coal char or coke,such as Na and Ca,behave as catalysts in gasification.The char/coke normally contains inherent SiO_(2),which can react with the inherent catalysts to form silica...Inherent metallic species retained by coal char or coke,such as Na and Ca,behave as catalysts in gasification.The char/coke normally contains inherent SiO_(2),which can react with the inherent catalysts to form silicates,resulting in catalyst deactivation over the range of pyrolysis,carbonization and gasification,and thereby reducing the char/coke reactivity.The present authors simulated the inherent catalyst deactivation experimentally by blending a Victorian lignite with SiO_(2),briquetting the SiO_(2)/lignite blend,carbonizing the briquette,and then gasifying the coke with CO_(2).The kinetic analysis of the gasification employed a comprehensive model,which assumed progress in parallel of non-catalytic and catalytic gasification.The model quantitatively described the measured kinetics of the coke gasification with different SiO_(2)contents over a range of coke conversion up to 99.9%.The kinetic analysis revealed that the SiO_(2)deactivated substantial and entire portions of the most active catalyst and its precursor,respectively,before the gasification(i.e.,during the carbonization).The catalyst deactivation also occurred during the gasification,but mainly following a self-deactivation mechanism that involved no silicates formation.展开更多
Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900℃ by applying a new method to continuously monitor the char surface activity.Benzene vapor was continuously forced to pass t...Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900℃ by applying a new method to continuously monitor the char surface activity.Benzene vapor was continuously forced to pass through a micro fixed bed of char with residence time as short as 7.6 ms,and then detected continuously by a flame-ionization detector.Results showed the presence of two different types of char surfaces;consumptive Type I surface and non-consumptive(sustainable)Type II surface.Type I surface of a partially CO_(2)-gasified char had an capacity of carbon deposit from benzene over 20 wt%-char and an initial activity(represented by a first-order rate constant)as high as 160 s−1.Both of them decreased with increasing carbon deposit due to consumption of micropores accessible to benzene,and finally became zero leaving Type II surface that had a very stable activity with rate constant of 4 s−1.The chars without gasification had capacities of Type I surfaces smaller by two orders of magnitude than the partially gasified char,while the Type II surfaces had activities similar to that of the partially gasified char.It was found that Type II surface converted benzene into not only carbon deposit but also diaromatics and even greater aromatics.Composition of the greater aromatics was unknown because they were deposited onto the reactor wall immediately after passing through the char bed.展开更多
The current state of lignin has been characterized by these three:(1)as one of the main components in lignocellulosic biomass with an abundant amount;(2)not be taken seriously but treated as a waste product;(3)underut...The current state of lignin has been characterized by these three:(1)as one of the main components in lignocellulosic biomass with an abundant amount;(2)not be taken seriously but treated as a waste product;(3)underutilized due to a complex and stubborn structure.However,lignin can be a rich source for hydrocarbons and aromatic compounds when gives appropriate utilization.In this work,we have studied the hydrotreatment of alkaline lignin(AL)under relatively mild conditions and further investigated the characterization of hydrogenated lignin(HL),especially the behavior during fast pyrolysis.The recovery of the HL decreased with increasing reaction temperature from 60 wt.%to 41 wt.%in the range of 150-250℃.The hydrotreated products were analyzed using Elemental Analysis,FTIR(for HL)and GC-MS(for bio-oil).The HL samples were found to have a higher hydrogen/carbon atomic effective ratio(H/C_(eff) ratio)and a higher degree of saturation than AL.Compared to the internal structure of the lignin before and after hydrotreatment,the side chain groups were removed from AL during the process.After that,from the fast pyrolysis of HL,it was observed that more light hydrocarbons and aromatic compounds were formed than that of AL.Furthermore,fast pyrolysis in the hydrogen atmosphere revealed that more volatile fractions were released compared to the Helium atmosphere.The total olefins yield was increased for HL compared AL from 1.02 wt.%to 3.1 wt.%at 250℃for 7 hours.This study of HL is instructive to some extent for the industrial utilization of lignin.展开更多
文摘Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH4 H2O, CO, CO2, etc., during the coal pyrolysis is an important but confusing subject. In this paper, quadrupole mass spectronletry, gas chromatography, and ^l3C nuclear magnetic resonance are applied to real-time monitoring the formations of volatile products, off-line quantitative determination of the total products from the pyrolysis of a sub-bituminous coal (SC), and the changes of diverse substitents in the SC along with coke foamation, respectively. These measurements are also performed for the pyrolysis of a caking coal to contrast SC. The qualitative and quantitative data reveal that, during coal pyrolysis, the functional groups related with the formation of CO, i.e., ether, carbonyl, and anhydride, can directly gen erate CO via bond breaking, or take a detour of the formation of other intermediates via condensation and recombination firstly. Moreover, the formations of CO2 and CH4 are related to the direct removal of -COO- and -CH3,respectively.
基金A part of this work was financially supported by the Japan Society for the Promotion of Science(JSPS)for Grant-in-Aid for Scientific Research A(Grant 17H01340)。
文摘Inherent metallic species retained by coal char or coke,such as Na and Ca,behave as catalysts in gasification.The char/coke normally contains inherent SiO_(2),which can react with the inherent catalysts to form silicates,resulting in catalyst deactivation over the range of pyrolysis,carbonization and gasification,and thereby reducing the char/coke reactivity.The present authors simulated the inherent catalyst deactivation experimentally by blending a Victorian lignite with SiO_(2),briquetting the SiO_(2)/lignite blend,carbonizing the briquette,and then gasifying the coke with CO_(2).The kinetic analysis of the gasification employed a comprehensive model,which assumed progress in parallel of non-catalytic and catalytic gasification.The model quantitatively described the measured kinetics of the coke gasification with different SiO_(2)contents over a range of coke conversion up to 99.9%.The kinetic analysis revealed that the SiO_(2)deactivated substantial and entire portions of the most active catalyst and its precursor,respectively,before the gasification(i.e.,during the carbonization).The catalyst deactivation also occurred during the gasification,but mainly following a self-deactivation mechanism that involved no silicates formation.
基金A part of this work was financially supported by New Energy and Industrial Technology Development Organization,Japan,for an R/D project on next-generation coal gasification system.Another part was supported by the Japan Society for the Promotion of Science(JSPS)for Grant-in-Aid for Scientific Research(Grant 17H01340).
文摘Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900℃ by applying a new method to continuously monitor the char surface activity.Benzene vapor was continuously forced to pass through a micro fixed bed of char with residence time as short as 7.6 ms,and then detected continuously by a flame-ionization detector.Results showed the presence of two different types of char surfaces;consumptive Type I surface and non-consumptive(sustainable)Type II surface.Type I surface of a partially CO_(2)-gasified char had an capacity of carbon deposit from benzene over 20 wt%-char and an initial activity(represented by a first-order rate constant)as high as 160 s−1.Both of them decreased with increasing carbon deposit due to consumption of micropores accessible to benzene,and finally became zero leaving Type II surface that had a very stable activity with rate constant of 4 s−1.The chars without gasification had capacities of Type I surfaces smaller by two orders of magnitude than the partially gasified char,while the Type II surfaces had activities similar to that of the partially gasified char.It was found that Type II surface converted benzene into not only carbon deposit but also diaromatics and even greater aromatics.Composition of the greater aromatics was unknown because they were deposited onto the reactor wall immediately after passing through the char bed.
基金supported by Japan Science and Technology Agency Strategic International Collaborative Research Program(JST SICORP)Grant Number JPMJSC18H1,Japanthe financial support of the China Scholarships Council(Grant Numbers 201906730062).
文摘The current state of lignin has been characterized by these three:(1)as one of the main components in lignocellulosic biomass with an abundant amount;(2)not be taken seriously but treated as a waste product;(3)underutilized due to a complex and stubborn structure.However,lignin can be a rich source for hydrocarbons and aromatic compounds when gives appropriate utilization.In this work,we have studied the hydrotreatment of alkaline lignin(AL)under relatively mild conditions and further investigated the characterization of hydrogenated lignin(HL),especially the behavior during fast pyrolysis.The recovery of the HL decreased with increasing reaction temperature from 60 wt.%to 41 wt.%in the range of 150-250℃.The hydrotreated products were analyzed using Elemental Analysis,FTIR(for HL)and GC-MS(for bio-oil).The HL samples were found to have a higher hydrogen/carbon atomic effective ratio(H/C_(eff) ratio)and a higher degree of saturation than AL.Compared to the internal structure of the lignin before and after hydrotreatment,the side chain groups were removed from AL during the process.After that,from the fast pyrolysis of HL,it was observed that more light hydrocarbons and aromatic compounds were formed than that of AL.Furthermore,fast pyrolysis in the hydrogen atmosphere revealed that more volatile fractions were released compared to the Helium atmosphere.The total olefins yield was increased for HL compared AL from 1.02 wt.%to 3.1 wt.%at 250℃for 7 hours.This study of HL is instructive to some extent for the industrial utilization of lignin.
