Hydride hydrogen separation-purification

Figure 15. Hydrogen separation-purification using hydrides...

The first successful synthesis of polycrystalline Mg CoH and its deuteride MgjCoDj was reported by Zolliker et al. [57]. The 2Mg-Co elemental mixture was sintered under 4.0-6.0 MPa of hydrogen at temperatures between 350 and 500°C. The formation of the hydride was not complete and the main remaining phases, MgH and Co had to be removed by a separate purification process. X-ray and neutron diffraction data suggested a tetragonally distorted CaF -type crystal structure... 

Copper sulfate, in small amounts, activates the zinc dust by forming zinc—copper couples. Arsenic(III) and antimony(TTT) oxides are used to remove cobalt and nickel they activate the zinc and form intermetaUic compounds such as CoAs (49). Antimony is less toxic than arsenic and its hydride, stibine, is less stable than arsine and does not form as readily. Hydrogen, formed in the purification tanks, may give these hydrides and venting and surveillance is mandatory. The reverse antimony procedure gives a good separation of cadmium and cobalt. 

Rechargeable metal hydrides have a number of potential applications in the "hydrogen economy" concept and in the present industrial sector. Because general surveys of hydride applications have been recently published(1,22,23), we will not try to review all the potential applications, but rather concentrate on a few that might be particularly applicable to the hydrogen industry storage containers, H2 compressors, H2 purification or separation, and deuterium separation. 

There are two basic routes for the commercial preparation of silane. The first involves the acid hydrolysis of magnesium silicide (Mg2S ) to give a mixture of silicon hydrides, which are then separated by fractional distillation. The second method involves the direct or indirect reduction of chlorosilane compounds with hydrogen to give silane. Further purification is generally necessary [11]. 

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