In gaseous products of biomass steam gasification, there exist a lot of CO, CH4 and other hydrocarbons that can be converted to hydrogen through steam reforming reactions. There exists potential hydrogen production fr...In gaseous products of biomass steam gasification, there exist a lot of CO, CH4 and other hydrocarbons that can be converted to hydrogen through steam reforming reactions. There exists potential hydrogen production from the raw gas of biomass steam gasification. In the present work, the characteristics of hydrogen production from biomass steam gasification were investigated in a small-scale fluidized bed. In these experiments, the gasifying agent (air) was supplied into the reactor from the bottom of the reactor and the steam was added into the reactor above biomass feeding location. The effects of reaction temperature, steam to biomass ratio, equivalence ratio (ER) and biomass particle size on hydrogen yield and hydrogen yield potential were investigated. The experimental results showed that higher reactor temperature, proper ER, proper steam to biomass ratio and smaller biomass particle size will contribute to more hydrogen and potential hydrogen yield.展开更多
The stability and activity of alkaline carbonate catalysts in supercritical water coal gasification has been investigated using density functional theory method. Our calculations present that the adsorption of Na2CO3 ...The stability and activity of alkaline carbonate catalysts in supercritical water coal gasification has been investigated using density functional theory method. Our calculations present that the adsorption of Na2CO3 on coal are more stable than that of K2CO3, but the stability of Na2CO3 is strongly reduced as the cluster gets larger. In supercritical water system, the dispersion and stability of Na2CO3 catalyst on coal support is strongly improved. During coal gasification process, Na2CO3 transforms with supercritical water into NaOH and NaHCO3, which is beneficial for hydrogen production. The transformation process has been studied via thermodynamics and kinetics ways. The selectively catalytic mechanism of NaOH and the intermediate form of sodium-based catalyst in water-gas shift reaction for higher hydrogen production has also been investigated. Furthermore, NaOH can transform back to Na2CO3 after catalyzing the water-gas shift reaction. Thus, the cooperative effects between supercritical water and Na2CO3 catalyst form a benignant circle which greatly enhances the reaction rate of coal gasification and promotes the production of hydrogen.展开更多
Energy conversion and utilization, particularly carbon-based fuel burning in air phase, have caused great environmental pollution and serious problems to society. The reactions in water phase may have the potential to...Energy conversion and utilization, particularly carbon-based fuel burning in air phase, have caused great environmental pollution and serious problems to society. The reactions in water phase may have the potential to realize clean and efficient energy conversion and utilization. Coal gasification in supercritical water is a typical carbon-based fuel conversion process in water phase, and it takes the advantages of the unique chemical and physical properties of supercritical water to convert organic matter in coal to H2 and CO2. N, S, P, Hg and other elements are deposited as inorganic salts to avoid pollution emission. The State Key Laboratory of Multiphase Flow in Power Engineering has obtained extensive experimental and theoretical results based on coal gasification in supercritical water. Supercritical water fluidized bed reactor was developed for coal gasification and seven kinds of typical feedstock were selected. The hydrogen yield covers from 0.67 to 1.74 Nm3/kg and the carbon gasification efficiency is no less than 97%. This technology has a bright future in industrialization not only in electricity generation but also in hydrogen production and high value-added chemicals. Given the gas yield obtained in laboratory-scale unit, the hydrogen production cost is U.S.$ 0.111 Nm3 when the throughput capacity is 2000 t/d. A novel thermodynamic cycle power generation system based on coal gasification in supercritical water was proposed with the obvious advantages of high coal-electricity conversion efficiency and zero pollutant emission. The cost of U.S.$ 3.69 billion for desulfuration, denitration and dust removal in China in 2013 would have been saved with this technology. Five kinds of heat supply methods are analyzed and the rates of return of investment are roughly estimated. An integrated cooperative innovation center called a new type of high-efficient coal gasification technology and its large-scale utilization was founded to enhance the industrialization of the technology vigorously.展开更多
Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed t...Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed to boost H2 generation during polyethylene gasification. The polymer is comilled with calcium and nickel hydroxides and then it is subjected to thermal treatment. Results demonstrate the key role played by the calcium hydroxide that significantly ameliorates hydrogen production. It reacts in solid state with the polyethylene to fonn directly carbonate and hydrogen. In this way, the CO2 is immediately captured in solid fonn, thus shifting the equilibrium toward H2 generation and obtaining high production rate (>25 L/mol CH2). In addition, high amounts of the hydroxide prevent excessive methane fonnation, so the gas product is almost pure hydrogen (~95%).展开更多
Cellulose,one of the important components of biomass,was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure.K_(2)CO_(3) and Ca(OH)2 were sele...Cellulose,one of the important components of biomass,was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure.K_(2)CO_(3) and Ca(OH)2 were selected as the catalysts(or promoters).The temperature was kept between 450uC and 500uC while pressure was maintained at 24–26 MPa.The reaction time was 20 min.Experimental results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each catalyst.When 0.2 g K_(2)CO_(3) was added,the hydrogen yield could reach 9.456 mol?kg21 which was two times of the H2 amount produced without catalyst.When 1.6 g Ca(OH)2 was added,the H2 yield was 8.265 mol?kg21 which is lower than that obtained using K_(2)CO_(3) as catalyst but is still 1.7 times that achieved without catalyst.Comparing with the results obtained using K_(2)CO_(3) or Ca(OH)2 alone,the use of a combination of K_(2)CO_(3) and Ca(OH)2 could increase the H2 yield by up to 2.5 times that without catalyst and 25%and 45%more than that obtained using K_(2)CO_(3) and Ca(OH)2 alone,respectively.It was found that methane was the dominant product at relatively low temperature.When the temperature was increased,the methane reacts with water and is converted to hydrogen and carbon dioxide.展开更多
Supercritical water gasification is a promising technology for wet biomass utilization.In this paper,Ni and other metal catalysts were synthesized by wet impregnation.The stability and catalytic activities of Ni catal...Supercritical water gasification is a promising technology for wet biomass utilization.In this paper,Ni and other metal catalysts were synthesized by wet impregnation.The stability and catalytic activities of Ni catalysts were evaluated.Firstly,catalytic activities of Ni,Fe,Cu catalysts supported on MgO were tested using wheat straw as raw material in a batch reactor at 723 K and water density of 0.07 cm^(3)/g.Experimental results showed that the order of metal catalyst activity for hydrogen generation was Ni/MgO>Fe/MgO>Cu/MgO.Secondly,the influence of different supports on Ni catalysts performance was investigated.The results showed that the order of the Ni catalysts’activity with different supports was Ni/MgO>Ni/ZnO>Ni/Al_(2)O_(3)>Ni/ZrO_(2).Finally,the effects of Ni loading and the amount of Ni catalyst addition on hydrogen production,and the stability of Ni/MgO catalyst were studied.It was found that serious deactivation of Ni catalyst in the process of supercritical water gasification took place.Even if carbon deposited on the catalyst surface was removed by high temperature calcination and the catalyst was reduced with hydrogen,the activity of used catalyst was only partially restored.展开更多
The world is endowed with a tremendous amount of coal resources,which are unevenly distributed in a few nations.While sustainable energy resources are being developed and deployed,fossil fuels dominate the current wor...The world is endowed with a tremendous amount of coal resources,which are unevenly distributed in a few nations.While sustainable energy resources are being developed and deployed,fossil fuels dominate the current world energy consumption.Thus,low-carbon clean technologies,like underground coal gasification(UCG),ought to play a vital role in energy supply and ensuring energy security in the foreseeable future.This paper provides a state-of-the-art review of the world's development of UCG for enhanced hydrogen production.It is revealed that the world has an active interest in decarbonizing the coal industry for hydrogen-oriented research in the context of UCG.While research is ongoing in multiple coal-rich nations,China dominates the world's efforts in both industrial-scale UCG pilots and laboratory experiments.A variety of coal ranks were tested in UCG for enhanced hydrogen output,and the possibilities of linking UCG with other prospective technologies had been proposed and critically scrutinized.Moreover,it is found that transborder collaborations are in dire need to propel a faster commercialization of UCG in an ever-more carbon-conscious world.Furthermore,governmental and financial support is necessary to incentivize further UCG development for large-scale hydrogen production.展开更多
以高湿污泥和玉米秸秆为原料,利用热重分析仪分析了2种物质掺混后的热解特性,并在固定床反应器中研究了污泥/秸秆共气化特性,考察了污泥与玉米秸秆不同掺混质量比下合成气的变化情况。结果表明,污泥和秸秆掺混物比污泥表现出更优的热解...以高湿污泥和玉米秸秆为原料,利用热重分析仪分析了2种物质掺混后的热解特性,并在固定床反应器中研究了污泥/秸秆共气化特性,考察了污泥与玉米秸秆不同掺混质量比下合成气的变化情况。结果表明,污泥和秸秆掺混物比污泥表现出更优的热解特性。当污泥和秸秆掺混质量比为4∶6时,制氢效果最佳,H_(2)和CO的气体体积分数分别为49.56%和27.42%,H_(2)的产量为0.61 L/g。在此条件下,综合比较了共气化和污泥/秸秆其他处置方式所产生的碳排放量,共气化可实现负碳排放,碳减排量为1 812.17 kg CO_(2)/(t原料),表明污泥与秸秆共气化的碳减排潜力巨大,对环境的负面影响小,是一项可同时实现污泥/玉米秸秆资源化利用、高效气化制氢和节能减排等多重目标的制氢技术。展开更多
基金Supported by the National Natural Science Foundation of China (No. 20206031)
文摘In gaseous products of biomass steam gasification, there exist a lot of CO, CH4 and other hydrocarbons that can be converted to hydrogen through steam reforming reactions. There exists potential hydrogen production from the raw gas of biomass steam gasification. In the present work, the characteristics of hydrogen production from biomass steam gasification were investigated in a small-scale fluidized bed. In these experiments, the gasifying agent (air) was supplied into the reactor from the bottom of the reactor and the steam was added into the reactor above biomass feeding location. The effects of reaction temperature, steam to biomass ratio, equivalence ratio (ER) and biomass particle size on hydrogen yield and hydrogen yield potential were investigated. The experimental results showed that higher reactor temperature, proper ER, proper steam to biomass ratio and smaller biomass particle size will contribute to more hydrogen and potential hydrogen yield.
基金supported by the National High-Tech Research and Development Program of China(2011AA05A201)the National Natural Science Foundation of China(21106094)Tianjin Science Foundation for Youths,China(12JCQNJC03100)
文摘The stability and activity of alkaline carbonate catalysts in supercritical water coal gasification has been investigated using density functional theory method. Our calculations present that the adsorption of Na2CO3 on coal are more stable than that of K2CO3, but the stability of Na2CO3 is strongly reduced as the cluster gets larger. In supercritical water system, the dispersion and stability of Na2CO3 catalyst on coal support is strongly improved. During coal gasification process, Na2CO3 transforms with supercritical water into NaOH and NaHCO3, which is beneficial for hydrogen production. The transformation process has been studied via thermodynamics and kinetics ways. The selectively catalytic mechanism of NaOH and the intermediate form of sodium-based catalyst in water-gas shift reaction for higher hydrogen production has also been investigated. Furthermore, NaOH can transform back to Na2CO3 after catalyzing the water-gas shift reaction. Thus, the cooperative effects between supercritical water and Na2CO3 catalyst form a benignant circle which greatly enhances the reaction rate of coal gasification and promotes the production of hydrogen.
基金supported by the National Natural Science Foundation of China(Grant Nos.5132301151306145&51236007)
文摘Energy conversion and utilization, particularly carbon-based fuel burning in air phase, have caused great environmental pollution and serious problems to society. The reactions in water phase may have the potential to realize clean and efficient energy conversion and utilization. Coal gasification in supercritical water is a typical carbon-based fuel conversion process in water phase, and it takes the advantages of the unique chemical and physical properties of supercritical water to convert organic matter in coal to H2 and CO2. N, S, P, Hg and other elements are deposited as inorganic salts to avoid pollution emission. The State Key Laboratory of Multiphase Flow in Power Engineering has obtained extensive experimental and theoretical results based on coal gasification in supercritical water. Supercritical water fluidized bed reactor was developed for coal gasification and seven kinds of typical feedstock were selected. The hydrogen yield covers from 0.67 to 1.74 Nm3/kg and the carbon gasification efficiency is no less than 97%. This technology has a bright future in industrialization not only in electricity generation but also in hydrogen production and high value-added chemicals. Given the gas yield obtained in laboratory-scale unit, the hydrogen production cost is U.S.$ 0.111 Nm3 when the throughput capacity is 2000 t/d. A novel thermodynamic cycle power generation system based on coal gasification in supercritical water was proposed with the obvious advantages of high coal-electricity conversion efficiency and zero pollutant emission. The cost of U.S.$ 3.69 billion for desulfuration, denitration and dust removal in China in 2013 would have been saved with this technology. Five kinds of heat supply methods are analyzed and the rates of return of investment are roughly estimated. An integrated cooperative innovation center called a new type of high-efficient coal gasification technology and its large-scale utilization was founded to enhance the industrialization of the technology vigorously.
文摘Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed to boost H2 generation during polyethylene gasification. The polymer is comilled with calcium and nickel hydroxides and then it is subjected to thermal treatment. Results demonstrate the key role played by the calcium hydroxide that significantly ameliorates hydrogen production. It reacts in solid state with the polyethylene to fonn directly carbonate and hydrogen. In this way, the CO2 is immediately captured in solid fonn, thus shifting the equilibrium toward H2 generation and obtaining high production rate (>25 L/mol CH2). In addition, high amounts of the hydroxide prevent excessive methane fonnation, so the gas product is almost pure hydrogen (~95%).
文摘Cellulose,one of the important components of biomass,was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure.K_(2)CO_(3) and Ca(OH)2 were selected as the catalysts(or promoters).The temperature was kept between 450uC and 500uC while pressure was maintained at 24–26 MPa.The reaction time was 20 min.Experimental results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each catalyst.When 0.2 g K_(2)CO_(3) was added,the hydrogen yield could reach 9.456 mol?kg21 which was two times of the H2 amount produced without catalyst.When 1.6 g Ca(OH)2 was added,the H2 yield was 8.265 mol?kg21 which is lower than that obtained using K_(2)CO_(3) as catalyst but is still 1.7 times that achieved without catalyst.Comparing with the results obtained using K_(2)CO_(3) or Ca(OH)2 alone,the use of a combination of K_(2)CO_(3) and Ca(OH)2 could increase the H2 yield by up to 2.5 times that without catalyst and 25%and 45%more than that obtained using K_(2)CO_(3) and Ca(OH)2 alone,respectively.It was found that methane was the dominant product at relatively low temperature.When the temperature was increased,the methane reacts with water and is converted to hydrogen and carbon dioxide.
基金This work is currently supported by the Key Project of Chinese National Programs for Research and Development(No.2016YFB0600102)National Nature Science Foundation of China(No.51676158)Shaanxi Science&Technology Co-ordination&Innovation Project(No.2016KTZDGY08-02).
文摘Supercritical water gasification is a promising technology for wet biomass utilization.In this paper,Ni and other metal catalysts were synthesized by wet impregnation.The stability and catalytic activities of Ni catalysts were evaluated.Firstly,catalytic activities of Ni,Fe,Cu catalysts supported on MgO were tested using wheat straw as raw material in a batch reactor at 723 K and water density of 0.07 cm^(3)/g.Experimental results showed that the order of metal catalyst activity for hydrogen generation was Ni/MgO>Fe/MgO>Cu/MgO.Secondly,the influence of different supports on Ni catalysts performance was investigated.The results showed that the order of the Ni catalysts’activity with different supports was Ni/MgO>Ni/ZnO>Ni/Al_(2)O_(3)>Ni/ZrO_(2).Finally,the effects of Ni loading and the amount of Ni catalyst addition on hydrogen production,and the stability of Ni/MgO catalyst were studied.It was found that serious deactivation of Ni catalyst in the process of supercritical water gasification took place.Even if carbon deposited on the catalyst surface was removed by high temperature calcination and the catalyst was reduced with hydrogen,the activity of used catalyst was only partially restored.
基金funded by PetroChina Research Institute of Petroleum Exploration&DevelopmentThe support of Department of Chemical and Petroleum Engineering,University of Calgary and Reservoir Simulation Group is gratefully acknowledged+1 种基金supported by NSERC/Energi Simulation,AITF(iCore),IBM Thomas J.Watson Research Center,and the Energi Simulation/Frank and Sarah Meyer Collaboration Centre for Visualization and Simulationsupport provided by WestGrid and Compute Canada Calcul Canada.
文摘The world is endowed with a tremendous amount of coal resources,which are unevenly distributed in a few nations.While sustainable energy resources are being developed and deployed,fossil fuels dominate the current world energy consumption.Thus,low-carbon clean technologies,like underground coal gasification(UCG),ought to play a vital role in energy supply and ensuring energy security in the foreseeable future.This paper provides a state-of-the-art review of the world's development of UCG for enhanced hydrogen production.It is revealed that the world has an active interest in decarbonizing the coal industry for hydrogen-oriented research in the context of UCG.While research is ongoing in multiple coal-rich nations,China dominates the world's efforts in both industrial-scale UCG pilots and laboratory experiments.A variety of coal ranks were tested in UCG for enhanced hydrogen output,and the possibilities of linking UCG with other prospective technologies had been proposed and critically scrutinized.Moreover,it is found that transborder collaborations are in dire need to propel a faster commercialization of UCG in an ever-more carbon-conscious world.Furthermore,governmental and financial support is necessary to incentivize further UCG development for large-scale hydrogen production.
文摘以高湿污泥和玉米秸秆为原料,利用热重分析仪分析了2种物质掺混后的热解特性,并在固定床反应器中研究了污泥/秸秆共气化特性,考察了污泥与玉米秸秆不同掺混质量比下合成气的变化情况。结果表明,污泥和秸秆掺混物比污泥表现出更优的热解特性。当污泥和秸秆掺混质量比为4∶6时,制氢效果最佳,H_(2)和CO的气体体积分数分别为49.56%和27.42%,H_(2)的产量为0.61 L/g。在此条件下,综合比较了共气化和污泥/秸秆其他处置方式所产生的碳排放量,共气化可实现负碳排放,碳减排量为1 812.17 kg CO_(2)/(t原料),表明污泥与秸秆共气化的碳减排潜力巨大,对环境的负面影响小,是一项可同时实现污泥/玉米秸秆资源化利用、高效气化制氢和节能减排等多重目标的制氢技术。
