Abstract: A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Mg(BH4)2, from the alkaline earth metal boride MgB2 by hydrogenating the MgB2 at an elevated temperature and pressure. The boride may also be doped with small amounts of a metal chloride catalyst such as TiCl3 and/or NiCl2. The process provides for charging MgB2 with high pressure hydrogen above at least 70 MPa while simultaneously heating the material to about 350° C. to about 400° C. The method is relatively simple and inexpensive and provides a reversible hydride compound having a hydrogen capacity of at least 11 wt %.

Abstract: A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Ca(BH4)2, from the alkaline earth metal hydride and the alkaline earth metal boride. The borohydride thus prepared is doped with a small portion of a metal chloride catalyst compound, such as RuCl3, TiCl3, or a mixture of TiCl3 and palladium metal. The process provides for mechanically mixing the dry reagents under an inert atmosphere followed by charging the mixed materials with high pressure hydrogen at about 70 MPa while heating the mixture to about 400° C. The method is relatively simple and inexpensive and provides reversible hydride compounds which are free of the usual contamination introduced by prior art wet chemical methods.