A series of layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers were prepared for co-production of syngas and pure hydrogen via chemical looping steam reforming(CLSR).The presence of magnesium-aluminum layered d...A series of layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers were prepared for co-production of syngas and pure hydrogen via chemical looping steam reforming(CLSR).The presence of magnesium-aluminum layered double oxides(Mg Al-LDO)significantly increases the specific surface area of the mixed oxides,reduces the particle size of CeO2-based solid solution and promotes the dispersion of free Fe2O3.When reacting with methane,Mg Al-LDO supported oxygen carrier shows much lower temperature for methane oxidation than the pure CeFe-Zr-O sample,indicating enhanced low-temperature reactivity.Among different Ce-Fe-Zr-O(x)/Mg Al-LDO samples,the Ce-Fe-Zr-O(40 wt%)/Mg Al-LDO sample shows the best performance for the selective oxidation of methane to syngas and the H2 production by water splitting.After a long period of high temperature redox experiment,the Ce-Fe-Zr-O(40 wt%)/Mg Al-LDO oxygen carrier still shows high activity for syngas generation.The comparison on the morphology of the fresh and cycled oxygen carriers indicates that the Mg-Al spinel support still forms a stable skeleton structure with high dispersion of active components on the surface after the long-term cycling,which contributes to excellent redox stability of the Ce-Fe-Zr-O(40 wt%)/Mg Al-LDO oxygen carrier.展开更多
The effects of plasma radiation on the nonlinear evolution of neo-classical tearing modes are investigated based on a set of reduced magnetohydrodynamic equations.It is found that the radiation can reduce the pressure...The effects of plasma radiation on the nonlinear evolution of neo-classical tearing modes are investigated based on a set of reduced magnetohydrodynamic equations.It is found that the radiation can reduce the pressure near the rational surface.During the nonlinear evolution,the magnitude of perturbed bootstrap current is drastically enhanced in the presence of the radiation.Besides,the radiation can increase the growth rate of the magnetic islands by diminishing the pressure,such that the magnetic islands do not saturate compared with that without radiation.On the other hand,with the increase of the ratio of parallel to perpendicular transport coefficientχ‖/χ⊥,the reduction of pressure can further increase the growth rate of magnetic islands in the presence of plasma radiation.Finally,the mechanisms of the destabilizing effects driven by the radiation are discussed in detail as well.展开更多
基金supported by the National Key R&D Program of China(2018YFB0605401)National Natural Science Foundation of China(Nos.51774159 and 51604137)the Qinglan Project of Kunming University of Science and Technology。
文摘A series of layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers were prepared for co-production of syngas and pure hydrogen via chemical looping steam reforming(CLSR).The presence of magnesium-aluminum layered double oxides(Mg Al-LDO)significantly increases the specific surface area of the mixed oxides,reduces the particle size of CeO2-based solid solution and promotes the dispersion of free Fe2O3.When reacting with methane,Mg Al-LDO supported oxygen carrier shows much lower temperature for methane oxidation than the pure CeFe-Zr-O sample,indicating enhanced low-temperature reactivity.Among different Ce-Fe-Zr-O(x)/Mg Al-LDO samples,the Ce-Fe-Zr-O(40 wt%)/Mg Al-LDO sample shows the best performance for the selective oxidation of methane to syngas and the H2 production by water splitting.After a long period of high temperature redox experiment,the Ce-Fe-Zr-O(40 wt%)/Mg Al-LDO oxygen carrier still shows high activity for syngas generation.The comparison on the morphology of the fresh and cycled oxygen carriers indicates that the Mg-Al spinel support still forms a stable skeleton structure with high dispersion of active components on the surface after the long-term cycling,which contributes to excellent redox stability of the Ce-Fe-Zr-O(40 wt%)/Mg Al-LDO oxygen carrier.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China(Nos.2019YFE03090300 and 2017YFE0301100)National Natural Science Foundation of China(Nos.11925501 and 12075048)the Fundamental Research Funds for the Central Universities(Nos.DUT21GJ204 and DUT21LK28)。
文摘The effects of plasma radiation on the nonlinear evolution of neo-classical tearing modes are investigated based on a set of reduced magnetohydrodynamic equations.It is found that the radiation can reduce the pressure near the rational surface.During the nonlinear evolution,the magnitude of perturbed bootstrap current is drastically enhanced in the presence of the radiation.Besides,the radiation can increase the growth rate of the magnetic islands by diminishing the pressure,such that the magnetic islands do not saturate compared with that without radiation.On the other hand,with the increase of the ratio of parallel to perpendicular transport coefficientχ‖/χ⊥,the reduction of pressure can further increase the growth rate of magnetic islands in the presence of plasma radiation.Finally,the mechanisms of the destabilizing effects driven by the radiation are discussed in detail as well.