This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz...This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH3, HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH3, but also promote the secondary reactions of the nascent char-N as well as the generation of NH3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen's (N-Q) formation in char.展开更多
The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer(TGA)at medium temperatures(650℃ ...The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer(TGA)at medium temperatures(650℃ to 800℃).The cation contents of potassium and sodium in samples were determined by Inductively Coupled Plasma Optical Emission Spectrometer(ICP-OES).The Brunauer-Emmett-Teller(BET)surface area of the samples was tested by N2 adsorption,and the morphologies of the samples were characterized by scanning electron microscopy(SEM).Experimental results showed that the organic sodium was the main catalyst for the gasification of the pyrolysis char,and the gasification rate of the char could be enhanced further with the introduction of CaO.The inherent alkali metals in coal and the introduced CaO showed a synergistic effect that occurred obviously above 735℃.The char conversion curves with or without CaO were fitted by the modified volumetric model(MVM).The calculated results indicated that the addition of CaO increased the pre-exponential factor obviously,but made little changes on the activation energy.It was proposed that the synergistic effect was resulted from the co-melting of the sodium and CaO,which facilitated the migration of the catalyst ions and the generation of C(O)intermediates for the gasification.展开更多
采用自制的气-固相反应装置研究了K/Na对焦炭与CO_2和水蒸汽气化反应的影响.结果表明,K/Na对焦炭与CO_2气化反应的催化作用强于对焦炭与水蒸汽反应的催化作用,焦炭中Na含量由0.045wt%增加到0.727wt%,焦炭与CO_2和水蒸汽气化反应的反应...采用自制的气-固相反应装置研究了K/Na对焦炭与CO_2和水蒸汽气化反应的影响.结果表明,K/Na对焦炭与CO_2气化反应的催化作用强于对焦炭与水蒸汽反应的催化作用,焦炭中Na含量由0.045wt%增加到0.727wt%,焦炭与CO_2和水蒸汽气化反应的反应性指数分别增加23.17%和14.35%,反应后焦炭强度分别降低27.55%和18.31%.焦炭中K/Na含量增加,焦炭与CO_2和水蒸汽气化反应明显开始温度、激烈反应温度和反应表观活化能均降低,焦炭中Na含量由0.045wt%增加到0.727wt%,焦炭与CO_2和水蒸汽气化反应明显开始温度分别降低170和20℃,激烈反应温度分别降低165和80℃,Na含量由0.045wt%增加到0.326wt%,表观活化能分别降低22.56和9.26 k J/mol.展开更多
基金The authors gratefully acknowledge the financial support provided by the 12th Five-Year Plan of National Science and Technology Support (Grant 2012BAA04B02)the National Natural Science Foundation of China (No.21406261).
文摘This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH3, HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH3, but also promote the secondary reactions of the nascent char-N as well as the generation of NH3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen's (N-Q) formation in char.
基金financially supported by the research project“Advancing and Demonstration of the Technology of CO2 Capture,Storage and Usage”(2016YFE0102500)National Natural Science Foundation of China(51606194)。
文摘The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer(TGA)at medium temperatures(650℃ to 800℃).The cation contents of potassium and sodium in samples were determined by Inductively Coupled Plasma Optical Emission Spectrometer(ICP-OES).The Brunauer-Emmett-Teller(BET)surface area of the samples was tested by N2 adsorption,and the morphologies of the samples were characterized by scanning electron microscopy(SEM).Experimental results showed that the organic sodium was the main catalyst for the gasification of the pyrolysis char,and the gasification rate of the char could be enhanced further with the introduction of CaO.The inherent alkali metals in coal and the introduced CaO showed a synergistic effect that occurred obviously above 735℃.The char conversion curves with or without CaO were fitted by the modified volumetric model(MVM).The calculated results indicated that the addition of CaO increased the pre-exponential factor obviously,but made little changes on the activation energy.It was proposed that the synergistic effect was resulted from the co-melting of the sodium and CaO,which facilitated the migration of the catalyst ions and the generation of C(O)intermediates for the gasification.
文摘采用自制的气-固相反应装置研究了K/Na对焦炭与CO_2和水蒸汽气化反应的影响.结果表明,K/Na对焦炭与CO_2气化反应的催化作用强于对焦炭与水蒸汽反应的催化作用,焦炭中Na含量由0.045wt%增加到0.727wt%,焦炭与CO_2和水蒸汽气化反应的反应性指数分别增加23.17%和14.35%,反应后焦炭强度分别降低27.55%和18.31%.焦炭中K/Na含量增加,焦炭与CO_2和水蒸汽气化反应明显开始温度、激烈反应温度和反应表观活化能均降低,焦炭中Na含量由0.045wt%增加到0.727wt%,焦炭与CO_2和水蒸汽气化反应明显开始温度分别降低170和20℃,激烈反应温度分别降低165和80℃,Na含量由0.045wt%增加到0.326wt%,表观活化能分别降低22.56和9.26 k J/mol.
