Preparation method of multi-light metal coordination aluminum hydride hydrogen storage material

[0019] Example 1

[0020] According to the chemical formula, it is Na x Li 3-x AlH 6 Coordination hydride hydrogen storage material, x=1.8 constitutes Na 1.8 Li 1.2 AlH 6 Coordination hydride. Using NaH, LiH and Al powder as raw materials and elemental Ti powder as catalyst, calculate the weight ratio of LiH, NaH and Al powder according to NaH:LiH:Al=1.8:1.2:1 (molar ratio), and then press (NaH+LiH) +Al) 4mol.% of the total molar amount to calculate the doping amount of Ti powder. The purity of NaH is ≥95% and the particle size is 74μm; the purity of LiH is ≥97% and the particle size is 74μm; the purity of Al powder is ≥99% and the particle size is 74-154μm; the purity of Ti powder is ≥99% and the particle size is <74μm. The raw materials and the catalyst are put into a ball mill tank and added to the mill balls at a ball-to-material ratio of 40:1. Before ball milling, evacuate the ball mill tank to a vacuum of 10 -3 bar, and then filled with 3.5MPa hydrogen with a purity greater than 99.9%, and then ball milled at room temperature for 120h. Prepared Na 1.8 Li 1.2 AlH 6 The measured hydrogen desorption capacity during the first desorption of hydrogen was 3.10 wt.%.

[0021] The main chemical reactions involved in the reaction process are:

[0022] The prepared coordination hydrides are all measured by the "constant volume-differential pressure method" for their hydrogen absorption and desorption properties. The subsequent hydrogen absorption and desorption cycle conditions are: hydrogen absorption at 100° C. and 5 MPa, and hydrogen release at 170-220° C. and 0.1 MPa (the same below).

[0023] figure 1 Na synthesized with Ti-doped catalyst 1.8 Li 1.2 AlH 6 Kinetic curve of the first hydrogen release of the coordination hydride. The prepared material can reach a hydrogen desorption capacity of 3.10wt.% when hydrogen is discharged at 200°C for 4.5 hours.

[0024] Example 2

[0025] According to the chemical formula, it is Na x Li 3-x AlH 6 Coordination hydride hydrogen storage material, x=2, which constitutes Na 2 LiAlH 6 Coordination hydride. Using NaH, LiH and Al powder as raw materials, TiF 3 As a catalyst, calculate the weight ratio of NaH, LiH and Al powder according to NaH:LiH:Al=2:1:1 (molar ratio), and then calculate TiF according to 2mol.% of the total molar amount of (NaH+LiH+Al) 3The amount of doping. The purity of the above NaH is ≥95%, and the particle size is 74μm; the purity of LiH is ≥97%, and the particle size is 74μm; the purity of Al powder is ≥99%, and the particle size is 74~154μm TiF 3 Powder purity ≥99%, particle size ≤154μm. The raw materials and the catalyst are put into a ball mill tank and added to the mill balls at a ball-to-material ratio of 30:1. Before ball milling, evacuate the ball mill tank to a vacuum of 10 -3 bar, and then filled with hydrogen with purity ≥99.9% and 2.5MPa, and then ball milled at room temperature for 100h, the prepared Na 2 LiAlH 6 The hydrogen storage capacity was measured to be 3.14wt.%.

[0026] The main chemical reactions involved in the reaction process are:

[0027] figure 2 TiF doped 3 Catalyst ball milling to synthesize Na 2 LiAlH 6 XRD patterns before and after coordination hydride. Na in ball milled synthetic materials 2 LiAlH 6 The content of coordination hydride is as high as 90%.

[0028] Example 3

[0029] According to the chemical formula, Na x Li 3-x AlH 6 Coordination hydride hydrogen storage material, x=2.4, which constitutes Na 2.4 Li 0.6 AlH 6 Coordination hydride. Use NaH, LiH and Al powder as raw materials. Select elemental V powder as the catalyst. First calculate the weight ratio of NaH, LiH and Al powder according to NaH:LiH:Al=2.4:0.6:1 (molar ratio), and then calculate the blending of V catalyst according to 4mol.% of the total molar amount of (NaH+LiH+Al) Impurities, the average particle size of V powder is about 50μm, and the purity is >99%. The raw material parameters such as purity and particle size of NaH, LiH and Al are the same as in Example 1. Before ball milling, evacuate the ball mill tank to a vacuum of 10 -3 bar, and then filled with 3.8MPa hydrogen with a purity greater than 99.99%, and then ball milled at room temperature for 130 hours to prepare Na 2.4 Li 0.6 AlH 6 The measured hydrogen storage capacity of the coordination hydride is 3.03wt.%.

[0030] The main chemical reactions involved in the reaction process are:

[0031] image 3 Na synthesized by ball milling with V catalyst 2.4 Li 0.6 AlH 6 The kinetic curve of the first hydrogen release of the coordination hydride and the comparison of the hydrogen release capacity of the first 10 cycles. Prepared Na 2.4 Li 0.6 AlH 6 The material can reach a hydrogen desorption capacity of 3.03wt.% within 4 hours when hydrogen is discharged for the first time at 190°C, and its hydrogen desorption capacity in the subsequent 10 hydrogen absorption and desorption cycles is maintained above 2.68wt.%.