The effects of Sr TiO_3 on the hydrogen storage properties of MgH_2 have been studied for the first time.The onset dehydrogenation temperature of the MgH_2-10 wt% SrTiO_3 is found to be 275 ℃, which is 55 ℃ lower as...The effects of Sr TiO_3 on the hydrogen storage properties of MgH_2 have been studied for the first time.The onset dehydrogenation temperature of the MgH_2-10 wt% SrTiO_3 is found to be 275 ℃, which is 55 ℃ lower as compared to the as-milled MgH_2. The composite is able to absorb 4.3 wt% of hydrogen in 60 min instead of 1.1 wt% for the as-milled Mg H_2. Meanwhile, the composite is able to release 5.3 wt% of hydrogen in 17 min compared to 1.9 wt% by the as-milled Mg H_2 at 320 ℃. The calculated Eaof the Mg H_2-10 wt% SrTiO_3 is 109 k J/mol, which is 26.3 kJ/mol lower than the calculated Eaof the as-milled MgH_2. The Sr TiO_3 is not decomposed during the ball milling and the re/dehydrogenation processes. The catalytic effect shown by the SrTiO_3 is owing to its ability to change the physical structure of the MgH_2 particles during the ball milling process.展开更多
The catalytic effect of K2SiF6 on MgH2 was first timely studied.The MgH2+5 wt.%K2SiF6 was prepared via the ball milling technique.The catalyst had lessened the initial decomposition temperature by 134℃ and 48℃ as co...The catalytic effect of K2SiF6 on MgH2 was first timely studied.The MgH2+5 wt.%K2SiF6 was prepared via the ball milling technique.The catalyst had lessened the initial decomposition temperature by 134℃ and 48℃ as compared to both pristine and milled MgH2 samples,respectively.In 2 minutes,4.5 wt.%of hydrogen was absorbed(250℃)by the doped composite,which was 0.8 wt.%higher than the milled MgH2.Meanwhile,for the desorption kinetics(320℃,1 atm),the amount of desorbed hydrogen was increased by 2.4 wt.%and 2.3 wt.%for the first 10 and 20 minutes.Besides,contracting volume and Johnson-Mehl-Avrami models were used to analyse the kinetics sorptions.The decomposition activation energy calculated based on Kissinger equation was 114 kJ/mol.As for the active species,Mg2Si,MgF2 and KH were formed during the heating process.These active species are speculated to be responsible for the improvement of the hydrogenation properties of the composite.展开更多
基金financially supported by the Ministry of Higher Education Malaysia under the Fundamental Research Grant Scheme (FRGS 59362)
文摘The effects of Sr TiO_3 on the hydrogen storage properties of MgH_2 have been studied for the first time.The onset dehydrogenation temperature of the MgH_2-10 wt% SrTiO_3 is found to be 275 ℃, which is 55 ℃ lower as compared to the as-milled MgH_2. The composite is able to absorb 4.3 wt% of hydrogen in 60 min instead of 1.1 wt% for the as-milled Mg H_2. Meanwhile, the composite is able to release 5.3 wt% of hydrogen in 17 min compared to 1.9 wt% by the as-milled Mg H_2 at 320 ℃. The calculated Eaof the Mg H_2-10 wt% SrTiO_3 is 109 k J/mol, which is 26.3 kJ/mol lower than the calculated Eaof the as-milled MgH_2. The Sr TiO_3 is not decomposed during the ball milling and the re/dehydrogenation processes. The catalytic effect shown by the SrTiO_3 is owing to its ability to change the physical structure of the MgH_2 particles during the ball milling process.
基金the Universiti Malaysia Terengganu(UMT)through the Golden Goose Research Grant(GGRG)(VOT 55190).
文摘The catalytic effect of K2SiF6 on MgH2 was first timely studied.The MgH2+5 wt.%K2SiF6 was prepared via the ball milling technique.The catalyst had lessened the initial decomposition temperature by 134℃ and 48℃ as compared to both pristine and milled MgH2 samples,respectively.In 2 minutes,4.5 wt.%of hydrogen was absorbed(250℃)by the doped composite,which was 0.8 wt.%higher than the milled MgH2.Meanwhile,for the desorption kinetics(320℃,1 atm),the amount of desorbed hydrogen was increased by 2.4 wt.%and 2.3 wt.%for the first 10 and 20 minutes.Besides,contracting volume and Johnson-Mehl-Avrami models were used to analyse the kinetics sorptions.The decomposition activation energy calculated based on Kissinger equation was 114 kJ/mol.As for the active species,Mg2Si,MgF2 and KH were formed during the heating process.These active species are speculated to be responsible for the improvement of the hydrogenation properties of the composite.
