Process for the storage of hydrogen using a system that strikes a balance between an alloy of alkaline metal and silicon and the corresponding hydride

Abstract

A process for the reversible storage of hydrogen, comprising bringing an alloy of alkaline metal and silicon into contact with gaseous hydrogen leading to the formation of the hydride or corresponding hydrides, comprises the use of at least one balanced system that corresponds to the formula: M X M Si M X M SiH n where M is selected from among Li, Na, or K and in which atomic ratios X M take on the following values: X Li =1

1 . Process for reversible storage of hydrogen comprising bringing into contact an alloy of alkaline metal and silicon with the gaseous hydrogen leading to the formation of hydride or corresponding hydrides, characterized in that a balanced system is used and said system corresponds to the formula:  
       M X     M   Si M X     M   SiH n    
     where M is selected from among Li, Na, or K, and in that atomic ratios X M  take on the following values:  
       X Li =1  1≦X Na ≦3  1≦X K ≦2  n is the number of hydrogen atoms corresponding to the stoiechiometry of the hydride or hydrides formed.    
   
   
       2 . Process for reversible storage of hydrogen comprising bringing into contact an alloy of alkaline metal and silicon with the gaseous hydrogen, leading to the formation of hydride or corresponding hydrides, wherein a balanced system that corresponds to the formula:  
       MSi X     Si     MSi X     Si   H 2X     Si     +1    
     where M is selected from among Li, Na, or K and in which the atomic ratio X Si =Si/M takes on a value of 1 to 4,  
     is used.  
   
   
       3 . Process for reversible storage of hydrogen according to  claim 1 , wherein the alkaline metal that is selected is lithium and wherein the hydride phase that is involved in the balanced system is the LiSiH 3  phase.  
   
   
       4 . Process for reversible storage of hydrogen according to  claim 1 , wherein the lithium can be partially substituted by sodium and/or potassium.  
   
   
       5 . Process for reversible storage of hydrogen according to  claim 1 , wherein the alkaline metal is selected from among sodium and potassium and involves the balanced system that corresponds to one of formulas:  
       Na X     Na   Si Na X     Na   SiH n  and  K X     K   Si K X     K   SiH n .  wherein the atomic ratios X M  take on the following values:      1≦X Na ≦3  1≦X K ≦2    n is the number of hydrogen atoms corresponding to the stoichiometry of the hydride or hydrides formed.    
   
   
       6 . Process for reversible storage of hydrogen according to  claim 1 , wherein the sodium can be partially substituted by lithium and/or potassium.  
   
   
       7 . Process for reversible storage of hydrogen according to  claim 1 , wherein the potassium can be partially substituted by lithium and/or sodium.  
   
   
       8 . Process according to  claim 1 , wherein the alloy also comprises, in a proportion that is less than 5% by weight, at least one light transition metal of groups 3 to 12 of the periodic table selected from among Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn.  
   
   
       9 . Process according to  claim 1 , wherein the alloy of alkaline metal and silicon comes in solid form.  
   
   
       10 . Process according to  claim 1 , wherein the alloy of alkaline metal and silicon is in dispersed form.  
   
   
       11 . Process according to  claim 10 , wherein the alloy of alkaline metal and silicon is obtained by grinding.  
   
   
       12 . Process according to  claim 1 , applied to the storage of on-board hydrogen.  
   
   
       13 . Process according to  claim 1 , applied to stationary storage.  
   
   
       14 . Process according to  claim 1 , applied to portable storage.  
   
   
       15 . New crystalline structure that corresponds to formula NaSiH 3  and belongs to space group PNMA.  
   
   
       16 . New crystalline structure corresponding to formula LiSiH 3  and belonging to space group PNMA.