Ca–Na–N–H system for reversible hydrogen storage

Hydrogen storage properties of LiNH 2 –LiH system with MgH 2 , CaH 2 and TiH 2 added

“…3 and 50.7 . According to previous published results [22,28], these peaks were associated with the formation of a solid solution 2CaNHeCa(NH 2 ) 2 . The FTIR bands at 3227 cm À1 and 3148 cm À1 , previously related with the solid solution 2CaNHeCa(NH 2 ) 2 , confirms its formation under cycling simultaneously with the presence of extra amount of LiNH 2 (bands at 3313 cm À1 and 3259 cm À1 ).…”

Mechanochemically driven nonequilibrium processes in MNH2–CaH2 systems (M=Li or Na)

“…[14] concluded that the overall reversible reaction in the Li-Ca-N-H system can be expressed as (4), and that the hydrogen capacity is 4.5 wt.%: (4) The "unknown imide phase", which forms after 400 • C, is Li 2 Ca(NH) 2 ternary imide isolated and characterized by Wu et al [13]. Recently, Ca-Na-N-H system was evaluated by Xiong et al [15]. Similar to other amide-hydride systems, interaction between Ca(NH 2 ) 2 and NaH (1:1) was observed in the temperature range of 120-270 • C with 1.1 wt.% of hydrogen desorbed, of which 0.96 wt.% of hydrogen can be recharged.…”

Improved Dehydrogenation Properties of Calcium Borohydride Combined with Alkaline-Earth Metal Amides

“…35 As for the Ca(BH 4 ) 2 À2Ca(NH 2 ) 2 sample, three peaks of the NÀH bond in FTIR result shown in Figure 1 are observed at 3228, 3289, and 3372 cm À1 , which are also different from those of pristine Ca(NH 2 ) 2 with four characteristic peaks at 3231, 3256, 3292, and 3316 cm À1 . 34 Furthermore, a broadened peak related to BÀH band was narrowed for Ca(BH 4 ) 2 À2Mg(NH 2 ) 2 and Ca(BH 4 ) 2 À2Ca(NH 2 ) 2 in comparison with pristine Ca(BH 4 ) 2 , even though no hydrogen or ammonia was released from the mixture during ball-milling treatment. Because FTIR results cannot tell the detailed differences of BÀH bond for ball-milled samples, 11 B MAS NMR spectra were performed on Ca(BH 4 ) 2 À2Mg(NH 2 ) 2 , Ca(BH 4 ) 2 À 2Ca(NH 2 ) 2 , and pristine Ca(BH 4 ) 2 , which are shown in Figure 2 Only one distinct peak of hydrogen evolution can be observed at 360°C in the MS curve of pristine Ca(BH 4 ) 2 , without any detectable diborane and ammonia signal in the MS tracks within the temperature range (20À500°C).…”