In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs,three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-p...In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs,three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-pressure core displacement experiments.Fine quantitative characterization of the cores in three steady states(original,after sulfur injection,and after gas flooding)was carried out using the nuclear magnetic resonance(NMR)transverse relaxation time spectrum and imaging,X-ray computer tomography(CT)of full-diameter cores,basic physical property testing,and field emission scanning electron microscopy imaging.The loss of pore volume caused by sulfur deposition and adsorption mainly comes from the medium and large pores with sizes bigger than 1000μm.Liquid sulfur has a stronger adsorption and deposition ability in smaller pore spaces,and causes greater damage to reservoirs with poor original pore structures.The pore structure of the three types of carbonate reservoirs shows multiple fractal characteristics.The worse the pore structure,the greater the change of internal pore distribution caused by liquid sulfur deposition and adsorption,and the stronger the heterogeneity.Liquid sulfur deposition and adsorption change the pore size distribution,pore connectivity,and heterogeneity of the rock,which further changes the physical properties of the reservoir.After sulfur injection and gas flooding,the permeability of TypeⅠreservoirs with good physical properties decreased by 16%,and that of TypesⅡandⅢreservoirs with poor physical properties decreased by 90%or more,suggesting an extremely high damage.This indicates that the worse the initial physical properties,the greater the damage of liquid sulfur deposition and adsorption.Liquid sulfur is adsorbed and deposited in different types of pore space in the forms of flocculence,cobweb,or retinitis,causing different changes in the pore structure and physical property of the reservoir.展开更多
The rational fabrication of an efficient heterojunction is critical to the enhancement of photocatalytic hydrogen(H_(2)) evolution performance.Herein,a new-fashioned graphitic-carbon nitride(g-C_(3) N_(4)) based isoty...The rational fabrication of an efficient heterojunction is critical to the enhancement of photocatalytic hydrogen(H_(2)) evolution performance.Herein,a new-fashioned graphitic-carbon nitride(g-C_(3) N_(4)) based isotype step-scheme(S-scheme) heterojunction composed of sulfur-doped and sulfur-free active sites is developed by liquid sulfur-mediation of exfoliated g-C_(3) N_(4).Particularly,the liquid sulfur not only contributes to the full contact between sulfur species and exfoliated g-C_(3) N_(4),but also creates sulfur-doping and abundant pores,since self-gas foaming effect of sulfur vapor.Moreover,the S-doped and S-free active sites located in the structural unit of C_(3) N_(4) jointly construct a typical sulfur-doped g-C_(3) N_(4)/g-C_(3) N_(4) isotype step-scheme heterojunction,which endows highly efficient photocatalytic reaction process.Therefore,the optimal sample possesses remarkable photocatalytic H_(2) evolution activity(5548.1 μmol g^(-1) h^(-1)) and robust durability.Most importantly,the investigation will open up a new path for the exploration of other carbon-based isotype S-scheme heterojunctions.展开更多
Solid-liquid phase conversion between various sulfur species in lithium-sulfur(Li-S)batteries is a fundamental reaction of the sulfur cathode.Disclosing the morphological evolution of solid sulfur species upon cycling...Solid-liquid phase conversion between various sulfur species in lithium-sulfur(Li-S)batteries is a fundamental reaction of the sulfur cathode.Disclosing the morphological evolution of solid sulfur species upon cycling is of great significance to achieving high energy densities.However,an in-depth investigation of the internal reaction is still lacking.In this work,the evolution process of solid sulfur species on carbon substrates is systematically studied by using an operando light microscope combined with in situ electrochemical impedance spectra technology.The observation of phenomena such as bulk solid sulfur species can form and dissolve independently of the conductive substrates and the transformation of supercooled liquid sulfur to crystalline sulfur.Based on the phenomena mentioned above,a possible mechanism was proposed in which the dissolution reaction of solid sulfur species is a spatially free reaction that involves isotropic physical dissolution,diffusion of molecules,and finally the electrochemical reaction.Correspondingly,the formation of solid sulfur species tends to be a form of crystallization in a saturated solution rather than electrodeposition,as is commonly believed.Our findings offer new insights into the reaction of sulfur cathodes and provide new opportunities to design advanced sulfur cathodes for Li-S batteries.展开更多
基金Supported by the National Natural Science Foundation of China(U19B6003)Sinopec Technology Research Project(P20077kxjgz)。
文摘In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs,three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-pressure core displacement experiments.Fine quantitative characterization of the cores in three steady states(original,after sulfur injection,and after gas flooding)was carried out using the nuclear magnetic resonance(NMR)transverse relaxation time spectrum and imaging,X-ray computer tomography(CT)of full-diameter cores,basic physical property testing,and field emission scanning electron microscopy imaging.The loss of pore volume caused by sulfur deposition and adsorption mainly comes from the medium and large pores with sizes bigger than 1000μm.Liquid sulfur has a stronger adsorption and deposition ability in smaller pore spaces,and causes greater damage to reservoirs with poor original pore structures.The pore structure of the three types of carbonate reservoirs shows multiple fractal characteristics.The worse the pore structure,the greater the change of internal pore distribution caused by liquid sulfur deposition and adsorption,and the stronger the heterogeneity.Liquid sulfur deposition and adsorption change the pore size distribution,pore connectivity,and heterogeneity of the rock,which further changes the physical properties of the reservoir.After sulfur injection and gas flooding,the permeability of TypeⅠreservoirs with good physical properties decreased by 16%,and that of TypesⅡandⅢreservoirs with poor physical properties decreased by 90%or more,suggesting an extremely high damage.This indicates that the worse the initial physical properties,the greater the damage of liquid sulfur deposition and adsorption.Liquid sulfur is adsorbed and deposited in different types of pore space in the forms of flocculence,cobweb,or retinitis,causing different changes in the pore structure and physical property of the reservoir.
基金supported by the National Natural Science Foundation of China (Nos.62004143 and 21975084)the Central Government Guided Local Science and Technology Development Special Fund Project (No.2020ZYYD033)+5 种基金the Natural Science Foundation of Hubei Province (No.2021CFB133)the Opening Fund of Key Laboratory of Rare Mineral,Ministry of Natural Resources(No.KLRM-KF 202005)the Opening Fund of Key Laboratory for Green Chemical Process of Ministry of Education of Wuhan Institute of Technology (No.GCP202101)the Open Research Fund of Key Laboratory of Material Chemistry for Energy Conversion and Storage (HUST),Ministry of Education (No.2021JYBKF05)the Innovation Project of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education (No.LCX2021003)the 12^(th) Graduate Education Innovation Fund of Wuhan Institute of Technology (No.CX2020341)。
文摘The rational fabrication of an efficient heterojunction is critical to the enhancement of photocatalytic hydrogen(H_(2)) evolution performance.Herein,a new-fashioned graphitic-carbon nitride(g-C_(3) N_(4)) based isotype step-scheme(S-scheme) heterojunction composed of sulfur-doped and sulfur-free active sites is developed by liquid sulfur-mediation of exfoliated g-C_(3) N_(4).Particularly,the liquid sulfur not only contributes to the full contact between sulfur species and exfoliated g-C_(3) N_(4),but also creates sulfur-doping and abundant pores,since self-gas foaming effect of sulfur vapor.Moreover,the S-doped and S-free active sites located in the structural unit of C_(3) N_(4) jointly construct a typical sulfur-doped g-C_(3) N_(4)/g-C_(3) N_(4) isotype step-scheme heterojunction,which endows highly efficient photocatalytic reaction process.Therefore,the optimal sample possesses remarkable photocatalytic H_(2) evolution activity(5548.1 μmol g^(-1) h^(-1)) and robust durability.Most importantly,the investigation will open up a new path for the exploration of other carbon-based isotype S-scheme heterojunctions.
基金the financial support from The National Key Research and Development Program of China(2018YFB0104200)。
文摘Solid-liquid phase conversion between various sulfur species in lithium-sulfur(Li-S)batteries is a fundamental reaction of the sulfur cathode.Disclosing the morphological evolution of solid sulfur species upon cycling is of great significance to achieving high energy densities.However,an in-depth investigation of the internal reaction is still lacking.In this work,the evolution process of solid sulfur species on carbon substrates is systematically studied by using an operando light microscope combined with in situ electrochemical impedance spectra technology.The observation of phenomena such as bulk solid sulfur species can form and dissolve independently of the conductive substrates and the transformation of supercooled liquid sulfur to crystalline sulfur.Based on the phenomena mentioned above,a possible mechanism was proposed in which the dissolution reaction of solid sulfur species is a spatially free reaction that involves isotropic physical dissolution,diffusion of molecules,and finally the electrochemical reaction.Correspondingly,the formation of solid sulfur species tends to be a form of crystallization in a saturated solution rather than electrodeposition,as is commonly believed.Our findings offer new insights into the reaction of sulfur cathodes and provide new opportunities to design advanced sulfur cathodes for Li-S batteries.
