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Nanoscale CeAl_4 was directly synthesized by the thermal reaction between CeH_2 and nano-aluminum at300℃.Then nano CeAl_4-doped sodium alanate(NaAlH_4)was synthesized by ball milling NaH/Al with 0.04CeAl_4under hydrogen atmosphere at room temperature,and the catalytic efficiency of nanoscale CeAl_4 for hydrogen storage of NaAlH_4 was systematically investigated.It is shown that CeAl_4 can effectively improve the dehydrogenation properties of sodium alanate system.The 0.04CeAl_4-doped NaAlH_4 system starts to release hydrogen below 80℃,completes dehydrogenation within 10 min at 170℃,and exhibits good cycling de/hydrogenation kinetics at relatively lower temperature(100-140℃).Apparent activation energy of the dehydrogenation of NaAlH_4 can be effectively reduced by addition of CeAl_4,resulting in the decrease in desorption temperatures.Moreover,by analyzing the reaction kinetics of nano CeAl_4-doped NaAlH_4sample,both of the decomposition steps are conformed to a two-dimensional phase-boundary growth mechanism.The mechanistic investigations gained here can help to understand the de-/rehydrogenation behaviors of catalyzed complex metal hydride systems.
Nanoscale CeAl_4 was directly synthesized by the thermal reaction between CeH_2 and nano-aluminum at 300 ℃ .Then nano CeAl_4-doped sodium alanate (NaAlH_4) was synthesized by ball milling NaH / Al with 0.04CeAl_4under hydrogen atmosphere at room temperature, and the catalytic efficiency of It is shown that CeAl_4 can be used to improve the dehydrogenation properties of sodium alanate system. The 0.04CeAl_4-doped NaAlH_4 system starts to release hydrogen at 80 ℃, completes dehydrogenation within 10 min at 170 ℃ , and exhibiting good cycling de / hydrogenation kinetics at relatively lower temperature (100-140 ° C). Apparent activation energy of the dehydrogenation of NaAlH 4 can be reduced substantially by CeAl 4, resulting in the decrease in desorption temperatures. Moreover, by analyzing the reaction kinetics of nano CeAl_4-doped NaAlH_4sample, both of the decomposition steps are conformed to a two-dimensional phase-boundary growth mechanism. The mechanistic investigations gained here can help to understand the de- / rehydrogenation behaviors of catalyzed complex metal hydride systems.