Sorption isotherms of hydrocarbon and carbon dioxide （CO2） provide crucial information for designing processes to sequester CO2 and recover natural gas from unmineable coal beds. Methane （CH4）, ethane （C2H6）, an...Sorption isotherms of hydrocarbon and carbon dioxide （CO2） provide crucial information for designing processes to sequester CO2 and recover natural gas from unmineable coal beds. Methane （CH4）, ethane （C2H6）, and CO2 adsorption isotherms on dry coal and the temperature effect on their maximum sorption capacity have been studied by performing combined Monte Carlo （MC） and molecular dynamics （MD） simulations at temperatures of 308 and 370 K （35 and 97 ~C） and at pressures up to 10 MPa. Simulation results demonstrate that absolute sorption （expressed as a mass basis） divided by bulk gas density has negligible temperature effect on CH4, C2H6, and CO2 sorption on dry coal when pressure is over 6 MPa. CO2 is more closely packed due to stronger interaction with coal and the stronger interaction between CO2 mole- cules compared, respectively, with the interactions between hydrocarbons and coal and between hydrocarbons. The results of this work suggest that the ＂a＂ constant （pro- portional to TcPc） in the Peng-Robinson equation of state is an important factor affecting the sorption behavior of hydrocarbons. CO2 injection pressures of lower than 8 MPa may be desirable for CH4 recovery and CO2 sequestration. This study provides a quantitative under- standing of the effects of temperature on coal sorptioncapacity for CH4, C2H6, and CO2 from a microscopic perspective.展开更多
High-quality Bi2Se3 microcrystals were grown by the physical vapor transport （PVT） method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well facete...High-quality Bi2Se3 microcrystals were grown by the physical vapor transport （PVT） method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well faceted and have dimensions up to -200 μm, The growth proceeds by the layer-by-layer mecha- nism with the formation of flat low-growth rate facets. The phase composition of the grown crystals was identified by the X-ray single crystal structure analysis in space group R3m, a = 4.1356（3）, C= 28.634（5）A, Z=3 （R=0.0147）. The most probable twin planes in the tetradymite structure were evaluated by the pseudo translational sublattice merhad.展开更多
A series of Ln（Ⅲ） dipivaloylmethanates Ln（dpm）3 has been obtained. The crystalstructures of Tm（dpm）3 （1） and Yb（dpm）3 （2） were determined by X-ray analysis at 200（2） K（Pmn2b Z = 2; a = 17.7509（8）, b ...A series of Ln（Ⅲ） dipivaloylmethanates Ln（dpm）3 has been obtained. The crystalstructures of Tm（dpm）3 （1） and Yb（dpm）3 （2） were determined by X-ray analysis at 200（2） K（Pmn2b Z = 2; a = 17.7509（8）, b = 10.5805（4）, c = 9.8380（4） A, V = 1847.7（1） A3 for （1） and a =17.7272（6）, b = 10.5882（3）, c = 9.8440（3） A, V= 1847.7（1） A^3 for （2））. These data complete thestructural evaluation of lanthanoid tris-dipivaloylmethanates. Compounds 1 and 2 are isostructuralto the complexes Ln（dpm）3 （Ln -- Er and Lu）. It is demonstrated that the volatility of tris-dipivaloylmethanates of rare earth elements increases from the complex of Lu to that of La.展开更多
基金supported by the National Basic Research Program of China (2014CB239004)the ‘‘Element and Process Constraint Petroleum System Modeling’’ project (No. 2011A-0207) under the Petro China Science Innovation program
文摘Sorption isotherms of hydrocarbon and carbon dioxide （CO2） provide crucial information for designing processes to sequester CO2 and recover natural gas from unmineable coal beds. Methane （CH4）, ethane （C2H6）, and CO2 adsorption isotherms on dry coal and the temperature effect on their maximum sorption capacity have been studied by performing combined Monte Carlo （MC） and molecular dynamics （MD） simulations at temperatures of 308 and 370 K （35 and 97 ~C） and at pressures up to 10 MPa. Simulation results demonstrate that absolute sorption （expressed as a mass basis） divided by bulk gas density has negligible temperature effect on CH4, C2H6, and CO2 sorption on dry coal when pressure is over 6 MPa. CO2 is more closely packed due to stronger interaction with coal and the stronger interaction between CO2 mole- cules compared, respectively, with the interactions between hydrocarbons and coal and between hydrocarbons. The results of this work suggest that the ＂a＂ constant （pro- portional to TcPc） in the Peng-Robinson equation of state is an important factor affecting the sorption behavior of hydrocarbons. CO2 injection pressures of lower than 8 MPa may be desirable for CH4 recovery and CO2 sequestration. This study provides a quantitative under- standing of the effects of temperature on coal sorptioncapacity for CH4, C2H6, and CO2 from a microscopic perspective.
文摘High-quality Bi2Se3 microcrystals were grown by the physical vapor transport （PVT） method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well faceted and have dimensions up to -200 μm, The growth proceeds by the layer-by-layer mecha- nism with the formation of flat low-growth rate facets. The phase composition of the grown crystals was identified by the X-ray single crystal structure analysis in space group R3m, a = 4.1356（3）, C= 28.634（5）A, Z=3 （R=0.0147）. The most probable twin planes in the tetradymite structure were evaluated by the pseudo translational sublattice merhad.
文摘A series of Ln（Ⅲ） dipivaloylmethanates Ln（dpm）3 has been obtained. The crystalstructures of Tm（dpm）3 （1） and Yb（dpm）3 （2） were determined by X-ray analysis at 200（2） K（Pmn2b Z = 2; a = 17.7509（8）, b = 10.5805（4）, c = 9.8380（4） A, V = 1847.7（1） A3 for （1） and a =17.7272（6）, b = 10.5882（3）, c = 9.8440（3） A, V= 1847.7（1） A^3 for （2））. These data complete thestructural evaluation of lanthanoid tris-dipivaloylmethanates. Compounds 1 and 2 are isostructuralto the complexes Ln（dpm）3 （Ln -- Er and Lu）. It is demonstrated that the volatility of tris-dipivaloylmethanates of rare earth elements increases from the complex of Lu to that of La.
