Process for preparing Ti-doped hydrides

1. A Ti(OCH 3 ) 4 -doped alkali metal and/or alkaline-earth metal aluminium hydride, obtained by a process, comprising intimately mixing:

an alkali metal and/or alkaline-earth metal aluminium hydride, or

at least one alkali metal hydride and/or alkaline-earth metal hydride, metallic aluminium and H 2 ,

with from 0.5 to 20 mol % of Ti(OCH 3 ) 4 , based on the moles of Al in the prepared Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride.

2. A Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride according to claim 1 , wherein the Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride is Ti-doped NaAlH 4 , LiMg (AlH 4 ) 3 or Na 2 LiAlH 6 .

3. A Ti(OCH 3 ) 4 -doped alkali metal and/or alkaline-earth metal aluminium hydride according to claim 1 , obtained by a process wherein an alkali metal and/or alkaline-earth metal aluminium hydride is mixed with Ti(OCH 3 ) 4 and the alkali metal and/or alkaline-earth metal aluminium hydride is an aluminium hydride of the general formula:

A

p

⁡

(

1

-

x

)

m

n

+

⁢

B

px

n

m

+

⁢

AlH

3

+

p

with A, B=an alkali or alkaline-earth metal,

n,m=metal ion valence, i.e. 1, 2 or 3,

0≦x≦1, and

1≦p≦3.

4. A Ti(OCH 3 ) 4 -doped alkali metal and/or alkaline-earth metal aluminium hydride according to claim 1 , obtained by a process wherein at least one alkali and/or alkaline-earth metal hydride, metallic aluminium and H 2 are mixed with Ti(OCH 3 ) 4 and the alkali and/or alkaline-earth metal is selected from the group consisting of Na, Ca, Li and Mg.

5. A Ti(OCH 3 ) 4 -doped alkali metal and/or alkaline-earth metal aluminium hydride according to claim 4 , obtained by a process wherein:

a) 3 parts NaH, 4.5 parts H 2 and at least 3 parts Al, or

b) 2 parts LiH, 2 parts MgH 2 , 9 parts H 2 and at least 6 parts Al, or

c) 4 parts NaH, 2 parts LiH, 3 parts H 2 and at least 2 parts Al are mixed with Ti(OCH 3 ) 4 .

6. A Ti(OCH 3 ) 4 -doped alkali metal and/or alkaline-earth metal aluminium hydride according to claim 1 , obtained by a process wherein Ti(OCH 3 ) 4 is mixed in an amount in the range of from 1 to 10 mol %, based on the moles of Al in the prepared Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride.

7. A Ti(OCH 3 ) 4 -doped alkali metal and/or alkaline-earth metal aluminium hydride according to claim 6 , obtained by a process wherein Ti(OCH 3 ) 4 is mixed in an amount in the range of from 2 to 5 mol %, based on the moles of Al in the prepared Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride.

8. A process for reversibly desorbing and/or absorbing hydrogen using a Ti-doped alkali metal and/or alkaline earth metal aluminum hydride prepared by intimately mixing an alkali metal and/or an alkaline-earth metal aluminum hydride; or at least one alkali metal hydride and/or alkaline earth metal hydride, metallic aluminum and H 2 with from 0.5 to 20 mol % of Ti(OCH 3 ) 4 , based on the moles of Al in the prepared Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride comprising:

dehydrogenating the at least partially hydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride by subjecting the Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride to a temperature of in the range of from 20 to 140° C. and removing a hydrogen-comprising gas to obtain a hydrogen-comprising gas and an at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride; and/or

hydrogenating the at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride according to claim 1 or 2 by contacting the at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride with a hydrogen-comprising gas at a temperature in the range of from 115 to 180° C. and a hydrogen partial pressure above the equilibrium hydrogen pressure of the at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride to reversibly store hydrogen.

9. A process according to claim 8 , wherein during hydrogenating the at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride is contacted with the hydrogen-comprising gas at a temperature of in the range of from 120 to 160° C.

10. A process according to claim 8 , wherein during hydrogenation the at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride is contacted with an hydrogen-comprising gas at a pressure in the range of from 1 to 700 bar.

11. A process according to claim 8 , wherein during hydrogenation the at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride is contacted with an hydrogen-comprising gas at a pressure in the range of from 10 to 150 bar.

12. A process according to claim 8 , wherein during hydrogenation the at least partially dehydrogenated Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride is contacted with an hydrogen-comprising gas at a pressure in the range of from 50 to 100 bar.

13. A hydrogen storage material comprising a Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride obtained by a process comprising intimately mixing:

an alkali metal and/or alkaline-earth metal aluminium hydride, or

at least one alkali metal hydride and/or alkaline-earth metal hydride, metallic aluminium and H 2 ,

with from 0.5 to 20 mol % of Ti(OCH 3 ) 4 , based on the moles of Al in the prepared Ti-doped alkali metal and/or alkaline-earth metal aluminium hydride.