It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well unde...It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well understood yet.In this research,structure-Ⅱ(sⅡ)hydrate is synthesized using a methanepropane gas mixture with an initial mole ratio of 99:1,and it is found that large(5~(12)6~4)cages are cooccupied by multiple gases based on the rigid structure analysis of neutron diffraction data.The first principles calculation and molecular dynamics simulation are conducted to uncover the molecular mechanism for sⅡmethane-propane hydrate formation,revealing that the presence of propane inhibits the formation of structure-Ⅰ(sⅠ)hydrate but promotes sⅡhydrate formation.The results help to understand the accumulation mechanism of natural gas hydrate and benefit to optimize the condition for gas storage and transportation in hydrate form.展开更多
The replacement process of CH4 from CH4 hydrate formed in NaCl solution by using pressurized CO2 was investigated with a self-designed device at temperatures of 271.05, 273.15 and 275.05 K and a constant pressure of 3...The replacement process of CH4 from CH4 hydrate formed in NaCl solution by using pressurized CO2 was investigated with a self-designed device at temperatures of 271.05, 273.15 and 275.05 K and a constant pressure of 3.30 MPa. The mass fraction of the NaCl solution was either 0.5 wt% or 1.0 wt%. The effects of temperature and concentration of NaCl solution on the replacement process were investigated. Experimental results showed that high temperature was favorable to the replacement reaction but high NaCl concentration had a negative effect on the replacement process. Based on the experimental data, kinetic models of CH4 hydrate decomposition and CO2 hydrate formation in NaCl solution were established. The calculated activation energies suggested that both CH4 hydrate decomposition and CO2 hydrate formation are dominated by diffusion in the hydrate phase.展开更多
The title compound, [Cu2（CH3COO）4（C8H10N2）]n·nCH3CN 1 （C8H10N2, 4,4＇-bipy = 4,4＇-bipyridine）, has been solvothermally synthesized in CH3CN and characterized by X-ray diffraction. The crystal is of monocli...The title compound, [Cu2（CH3COO）4（C8H10N2）]n·nCH3CN 1 （C8H10N2, 4,4＇-bipy = 4,4＇-bipyridine）, has been solvothermally synthesized in CH3CN and characterized by X-ray diffraction. The crystal is of monoclinic, space group Cc with α = 22.626（6）, b = 14.012（4）, c = 15.106（4） ]A, β = 107.610（3）°, V = 4565（2） ]A^3, C20H23Cu2N3O8, Mr = 560.49, Z = 8, Dc = 1.631 g/cm^3,μ = 1.914 mm^-1, Flack parameter = 0.48（1）, F（000） = 2288, R = 0.042 and wR = 0.098 for 8887 observed reflections （I 〉 20（I））. It consists of nearly linear one-dimensional chains [Cu2（CH3COO）4（C8H10N2）]n derived from paddle-wheel [Cu2（CH3COO）4] unit linked by 4,4＇-bipy, and CH3CN as guest molecule regularly decorates between the chains.展开更多
基金supported by the National Key Research and Development Program of China(2016YFA0401503 and 2018YFA0305700)the National Natural Science Foundation of China(11575288,91934303,21935001 and 11775011)+4 种基金the Strategic Priority Research ProgramKey Research Program of Frontier Sciences of the Chinese Academy of Sciences(XDB33000000,XDB25000000 and QYZDBSSW-SLH013)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y202003)the China Geological Survey(DD20190234)the Scientific Instrument Developing Project(ZDKYYQ20170001)of the Chinese Academy of Sciences。
文摘It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well understood yet.In this research,structure-Ⅱ(sⅡ)hydrate is synthesized using a methanepropane gas mixture with an initial mole ratio of 99:1,and it is found that large(5~(12)6~4)cages are cooccupied by multiple gases based on the rigid structure analysis of neutron diffraction data.The first principles calculation and molecular dynamics simulation are conducted to uncover the molecular mechanism for sⅡmethane-propane hydrate formation,revealing that the presence of propane inhibits the formation of structure-Ⅰ(sⅠ)hydrate but promotes sⅡhydrate formation.The results help to understand the accumulation mechanism of natural gas hydrate and benefit to optimize the condition for gas storage and transportation in hydrate form.
基金support received from the National Natural Science Foundation of China (20476058,20676146)Ministry of Science and Technology of China (2006AA09A208,2009CB219504)Specialized Research Fund for the Doctoral Program of Higher Education (20070425001)
文摘The replacement process of CH4 from CH4 hydrate formed in NaCl solution by using pressurized CO2 was investigated with a self-designed device at temperatures of 271.05, 273.15 and 275.05 K and a constant pressure of 3.30 MPa. The mass fraction of the NaCl solution was either 0.5 wt% or 1.0 wt%. The effects of temperature and concentration of NaCl solution on the replacement process were investigated. Experimental results showed that high temperature was favorable to the replacement reaction but high NaCl concentration had a negative effect on the replacement process. Based on the experimental data, kinetic models of CH4 hydrate decomposition and CO2 hydrate formation in NaCl solution were established. The calculated activation energies suggested that both CH4 hydrate decomposition and CO2 hydrate formation are dominated by diffusion in the hydrate phase.
基金The work was supported by the Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces (No. 0506) and the University of Malaya (F0712/2005c)
文摘The title compound, [Cu2（CH3COO）4（C8H10N2）]n·nCH3CN 1 （C8H10N2, 4,4＇-bipy = 4,4＇-bipyridine）, has been solvothermally synthesized in CH3CN and characterized by X-ray diffraction. The crystal is of monoclinic, space group Cc with α = 22.626（6）, b = 14.012（4）, c = 15.106（4） ]A, β = 107.610（3）°, V = 4565（2） ]A^3, C20H23Cu2N3O8, Mr = 560.49, Z = 8, Dc = 1.631 g/cm^3,μ = 1.914 mm^-1, Flack parameter = 0.48（1）, F（000） = 2288, R = 0.042 and wR = 0.098 for 8887 observed reflections （I 〉 20（I））. It consists of nearly linear one-dimensional chains [Cu2（CH3COO）4（C8H10N2）]n derived from paddle-wheel [Cu2（CH3COO）4] unit linked by 4,4＇-bipy, and CH3CN as guest molecule regularly decorates between the chains.
