Microwave irradiation effects on reversible hydrogen desorption in sodium aluminum hydrides (NaAlH4)

Diffusion controlled hydrogen desorption reaction for the LiBH4/2LiNH2 system

“…The Avrami exponent n, as determined from the slope of the JMA plot, ranges from 1.01 to 1.22 which is very close to 1 for the LiBH 4 /2LiNH 2 and LiBH 4 /2LiNH 2 +5 wt%Co samples as shown in Table 1. The Avrami exponent provides insights into the transformation mechanism geometry and the rate-controlling mechanism of the heterogeneous chemical reaction, which can be expressed as dimensionality and growth parameters [29,30], n = d m + 1 for continuous nucleation model (5) n = d m for site saturation model (6) where d is the dimensionality of the growth (d = 1, 2, 3 for 1D, 2D and 3D growth respectively), m is a growth index dependent on the rate controlling step of transformation (m = 1 for interface controlled growth and m = 2 for diffusion controlled growth). Previous reports have pointed out that the hydrogen desorption of LiBH 4 /2LiNH 2 occurs after ␣ phase (Li 4 BN 3 H 10 ) melting [12,16,21,22], and consequently the Li 3 BN 2 product is formed in a liquid environment.…”

“…Although some metals and alloys can absorb hydrogen at room temperature their lower gravimetric densities prevent their on-board applications [2]. Light-element complex hydrides such as alanates (AlH 4 − ), borohydrides (BH 4 − ) and amides/imides (NH 2 − /NH 2− ) that are presently regarded as the most promising candidates for practical applications due to their higher hydrogen content have attracted an increasing amount of attention [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Synthesis and Characterization of Metal Hydride/Carbon Aerogel Composites for Hydrogen Storage

“…Ti-doping also improves significantly the kinetic and cycling performance of NaAlH 4 at moderate temperatures around 373 K and ambient pressures. All these properties make it suitable as mobile, lightweight H 2 storage materials for potential application on a hydrogen fuel cell [11][12][13][14][15][16][17][18][19][20][21][22][23]. Practically, achievable H 2 storage capacity for Ti-NaAlH 4 is only 3.7 wt%, falls short of the theoretical value of 5.6 wt% for NaAlH 4 [20][21][22][23].…”

Effect of microwave irradiation on hydrogen sorption properties of hand mixed MgH2 – 10 wt.% carbon fibers

“…These authors used a metal cylinder inside the sample holder as MW susceptor. Krishnan et al [19] explore the effect of microwave irradiation on the reversible desorption reaction in NaAlH 4 doped with 2 mol% TiCl 2 and pre-activated by high energy ball milling. More recently, considering the rapid heating character of LiBH 4 under microwave and the favorable cycle performance of MgH 2 , Leng et al [20] added LiBH 4 into MgH 2 and studied the effect of microwave radiation on the MgH 2 /LiBH 4 composite.…”