Two kinds of metal-organic frameworks(MOFs) based on Co(Ⅱ) and Fe(Ⅱ) as metal ions and trimasic acid(TMA) as organic linker were synthesized. They were used to prepare corresponding Mg H2-TM MOF(TM = Co, Fe) composi...Two kinds of metal-organic frameworks(MOFs) based on Co(Ⅱ) and Fe(Ⅱ) as metal ions and trimasic acid(TMA) as organic linker were synthesized. They were used to prepare corresponding Mg H2-TM MOF(TM = Co, Fe) composites via ball-milling. X-ray diffraction analyses show the formation of Mg2 Co and α-Fe phases in Mg H2-TMMOF composites after decomposition. Both of the well dispersed Mg2Co andα-Fe nanoparticles exhibit considerable catalytic efficiency in accelerating the sorption kinetics of Mg H2.The dehydrogenated MgH2-Fe MOF composite shows faster hydriding kinetics than the pure Mg H2 and Mg H2-CoMOF. Meanwhile, the apparent dehydrogenation activation energy(Ed) of the Mg H2-Co MOF and Mg H2-Fe MOF composites are 151.3 ± 9.4 and 142.3 ± 6.5 kJ/mol H2, both of which are lower than that of pure Mg H2(181.4 ± 9.2 kJ/mol H2). The improvement on the sorption kinetics of the Mg H2-TM MOF powders is mainly attributed to the catalytic effects of nano-sized Mg2 Co and α-Fe formed on the surface of Mg/Mg H2 particles.展开更多
Mesoscale eddies play a key role in the ocean dynamics of the Southern Ocean, and eddy response to the climate changes has also been widely noted. Both eddy kinetic energy（EKE） and eddy detection algorithm are used ...Mesoscale eddies play a key role in the ocean dynamics of the Southern Ocean, and eddy response to the climate changes has also been widely noted. Both eddy kinetic energy（EKE） and eddy detection algorithm are used to study the eddy properties in the Pacific sector of the Southern Ocean. Consistent with previous works,the maps of the EKE illustrate that higher energy confines to the Antarctic Polar Frontal Zone（APFZ） and decreases progressively from west to east. It also shows that the most significant increase in the EKE occurs in the western and central parts of the Pacific sector, where the baroclinicity of the Antarctic Circumpolar Current（ACC） is much stronger. Statistical eddy properties reveal that both of the spatial pattern and interannual variation of the EKE are primarily due to the eddy amplitude and the eddy rotational speed, rather than the eddy number or the eddy radius. In general, these results furtherly confirm that anomalous westerly wind forcing associated with the positive Southern Annular Mode（SAM） index enhances the Southern Ocean eddy activity by strengthening the eddy properties.展开更多
The effect of LaNi on thermal storage properties of MgH2 prepared by ball milling under hydrogen atmosphere was investigated.The thermal storage properties,cyclic property and thermal storage mechanism were studied by...The effect of LaNi on thermal storage properties of MgH2 prepared by ball milling under hydrogen atmosphere was investigated.The thermal storage properties,cyclic property and thermal storage mechanism were studied by pres sure-composition-temperature(PC T),X-ray diffraction(XRD)and transmission electron microscopy(TEM).The Van't Hoff curve indicates that the formation enthalpy of Mg-16 wt%LaNi is 74.62 kJ·mol^(-1),which approaches to the theoretical values of MgH2.The isothermal measurement indicates that Mg-16 wt%LaNi can absorb 6.263 wt%H_(2)within 30 min at 390℃for the first absorption,the absorption reaction fraction within2 min is over 90.00%,and the desorption reaction fraction within 2 min is 72.63%,increasing by 55.36%compared with that of Mg.Mg-16 wt%LaNi has better cyclic stability than that of Mg,only decreasing by 0.609 wt%after 80cycles.The enhancement in thermal storage performances of Mg by adding LaNi is mainly ascribed to the formed Mg_(2)NiH_(4),H_(0.3)Mg_(2)Ni and La_(4)H_(12.19)during the cyclic process which act as catalysts and inhibit the growth of Mg.The above results prove that Mg-16 wt%LaNi is suitable for use as a heat storage material.展开更多
基金supported financially by the National Natural Science Foundation of China (No. 51771112)the National Key Research & Development Project (No. 2018YFB1502104)+1 种基金the Shanghai Science and Technology Commission (No. 14JC1491600)the Shanghai Education Commission “Shuguang” Scholar Project (No. 16SG08)
文摘Two kinds of metal-organic frameworks(MOFs) based on Co(Ⅱ) and Fe(Ⅱ) as metal ions and trimasic acid(TMA) as organic linker were synthesized. They were used to prepare corresponding Mg H2-TM MOF(TM = Co, Fe) composites via ball-milling. X-ray diffraction analyses show the formation of Mg2 Co and α-Fe phases in Mg H2-TMMOF composites after decomposition. Both of the well dispersed Mg2Co andα-Fe nanoparticles exhibit considerable catalytic efficiency in accelerating the sorption kinetics of Mg H2.The dehydrogenated MgH2-Fe MOF composite shows faster hydriding kinetics than the pure Mg H2 and Mg H2-CoMOF. Meanwhile, the apparent dehydrogenation activation energy(Ed) of the Mg H2-Co MOF and Mg H2-Fe MOF composites are 151.3 ± 9.4 and 142.3 ± 6.5 kJ/mol H2, both of which are lower than that of pure Mg H2(181.4 ± 9.2 kJ/mol H2). The improvement on the sorption kinetics of the Mg H2-TM MOF powders is mainly attributed to the catalytic effects of nano-sized Mg2 Co and α-Fe formed on the surface of Mg/Mg H2 particles.
基金The Chinese Polar Science Strategy Research Foundation under contract No.20150305the National Natural Science Foundation of China under contract No.41406012+2 种基金the Shandong Provincial Natural Science Foundation of China under contract No.ZR2014DP011the Basic Scientific Research Fund for National Public Institutes of China under contract No.2015G05the Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences under contract No.KLOCAW1405
文摘Mesoscale eddies play a key role in the ocean dynamics of the Southern Ocean, and eddy response to the climate changes has also been widely noted. Both eddy kinetic energy（EKE） and eddy detection algorithm are used to study the eddy properties in the Pacific sector of the Southern Ocean. Consistent with previous works,the maps of the EKE illustrate that higher energy confines to the Antarctic Polar Frontal Zone（APFZ） and decreases progressively from west to east. It also shows that the most significant increase in the EKE occurs in the western and central parts of the Pacific sector, where the baroclinicity of the Antarctic Circumpolar Current（ACC） is much stronger. Statistical eddy properties reveal that both of the spatial pattern and interannual variation of the EKE are primarily due to the eddy amplitude and the eddy rotational speed, rather than the eddy number or the eddy radius. In general, these results furtherly confirm that anomalous westerly wind forcing associated with the positive Southern Annular Mode（SAM） index enhances the Southern Ocean eddy activity by strengthening the eddy properties.
基金financially supported by the Beijing Municipal Commission of Science and Technology of China(No.D141100002014001)。
文摘The effect of LaNi on thermal storage properties of MgH2 prepared by ball milling under hydrogen atmosphere was investigated.The thermal storage properties,cyclic property and thermal storage mechanism were studied by pres sure-composition-temperature(PC T),X-ray diffraction(XRD)and transmission electron microscopy(TEM).The Van't Hoff curve indicates that the formation enthalpy of Mg-16 wt%LaNi is 74.62 kJ·mol^(-1),which approaches to the theoretical values of MgH2.The isothermal measurement indicates that Mg-16 wt%LaNi can absorb 6.263 wt%H_(2)within 30 min at 390℃for the first absorption,the absorption reaction fraction within2 min is over 90.00%,and the desorption reaction fraction within 2 min is 72.63%,increasing by 55.36%compared with that of Mg.Mg-16 wt%LaNi has better cyclic stability than that of Mg,only decreasing by 0.609 wt%after 80cycles.The enhancement in thermal storage performances of Mg by adding LaNi is mainly ascribed to the formed Mg_(2)NiH_(4),H_(0.3)Mg_(2)Ni and La_(4)H_(12.19)during the cyclic process which act as catalysts and inhibit the growth of Mg.The above results prove that Mg-16 wt%LaNi is suitable for use as a heat storage material.
