Rare Earth Oxides And Pore Material Modification The Naalh <sub> 4 </ Sub> Absorption And Desorption Hydrogen Performance

To solve the problems of low storage capacity, low hydrogen release speed, and harsh hydrogen absorption conditions of hydrogen storage materials, we investigated the hydrogen storage capacity of NaAlH4 doped/and co-doped by lanthanide oxides and porous materials from the aspects of structure, morphology, thermoactivity, and hydrogen de/-reabsorption using the ball milling method.The catalytic effects of Sm2O3, Er2O3, and Tm2O3 on NaAlH4 were investigated, founding that all lanthanide oxides added can make hydrogen storage of NaAlH4 reversible, and samples could release hydrogen at 150℃with a higher speed. For pristine NaAlH4, NaAlH4-Sm2O3, NaAlH4-Er2O3, and NaAlH4-Tm2O3, the amount of hydrogen released within 8 h increased from less than 1 wt% to 3.90,4.40, and 4.59 wt%, respectively. The addition of Tm2O3 improved the hydrogen storage capacity of NaAlH4 at the maximum extent, reversible hydrogen desorption capacity of NaAlH4-Tm2O3 among five cycles was 4.59,1.96,1.51,1.86 and 1.39 wt%, respectively. The optimum milling time and catalyst dosage is 1 h and weight ratio of 10 wt%. Unexpectedly, NaAlH4-Tm2O3 can also release hydrogen at 120℃with a lower amount of 4.30 wt%.In addition, the effects of macroporous Al2O3 and mesoporous silica on NaAlH4 were investigated. The hydrogen storage capacity of NaAlH4-SiO2 and NaAlH4-Al2O3 was 3.59 wt% and 3.37 wt%, respectively. Then the co-effects of lanthanide oxides and porous materials were explored, and the hydrogen storage capacity of NaAlH4-Tm2O3-SiO2, NaAlH4-Tm2O3 and NaAlH4-Tm2O3-Al2O3 was 4.73,4.59 and 4.36 wt%, respectively. Samples co-doped by macroporous Al2O3/mesoporous silca and different lanthanide oxides showed similar hydrogen desorption speed and capacity trend, which was NaAlH4-SiO2-(MxOy,M=Sm,Tm,Er)>NaAlH4-(MxOy,M=Sm,Tm,Er)> NaAlH4-Al2O3-(MxOy,M=Sm,Tm,Er).