Electrolytic process to silicides
View Patent ↗An electrolytic process may be used to generate reactive metal silicides with Group 1 metals of the periodic table and/or Group 2 metals of the periodic table, and/or aluminum. Exemplary reactive metal silicides include magnesium silicide (Mg 2 Si).
1. A process comprising:
(i) heating a salt comprising (a) a halide of a metal of formula MX a , where M is selected from the group consisting of Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, and a combination thereof, subscript a is an integer of 1 or more, and each X is a halogen atom, thereby preparing a molten salt;
(ii) introducing to the molten salt, a gas comprising a silane of formula H b SiX (4-b) , where subscript b is an integer from 0 to 4, and passing an electric current through the molten salt, thereby producing an electrolysis product comprising a silicide of the metal.
2. The process of claim 1 , where one of conditions (a) and (b) is met, and
condition (a) is M is Al, K, Li, Mg, Na, or a combination thereof; or
condition (b) is M is Al, Ca, Mg, or a combination thereof.
3. The process of claim 1 , where the salt further comprises at least one of ingredients (b) and (c), where
ingredient (b) is a metal selected from Li, Na, K, Rb, Cs, Fr; Be, Mg, Ca, Sr, Ba, Ra, Al, or a combination thereof, and
ingredient (c) is an ionic liquid.
4. The process of claim 3 , where one of conditions (i) and (ii) is satisfied, and
condition (i) is (b), the metal, is Al, K, Li, Mg, Na, or a combination thereof; or
condition (ii) is (b), the metal, is Al, Ca, Mg, or a combination thereof.
5. The process of claim 1 , where b is 0 to 3.
6. The process of claim 1 , further comprising: drying the salt before step (i).
7. The process of claim 1 , where the gas in step (ii) further comprises H 2 .
8. The process of claim 1 , further comprising (iii) recovering a product comprising a metal silicide from the electrolysis product.
9. The process of claim 1 , where the process steps are performed under an inert gas atmosphere.
10. The process of claim 1 , where the electrolysis product comprises
(A) the metal silicide, and
(B) a second product comprising X 2 .
11. The process of claim 10 , further comprising: (iv) recovering the second product from the electrolysis product and optionally recycling the X 2 to a process for producing HX and/or to carbohalogenation reactions to generate SiX 4 .
12. The process of claim 10 , further comprising (v) reacting a halide of formula HX with the electrolysis product comprising the metal silicide, thereby preparing a reaction product comprising
(1) a product comprising one or more hydridosilanes of formulae SiH 4 , HSiX 3 , H 2 SiX 2 , and/or H 3 SiX; and
(2) a third product comprising MX a .
13. The process of claim 10 , further comprising (v) reacting the electrolysis product, with an aqueous acid, thereby preparing a reaction product comprising:
(1) a fourth product comprising one or more hydridosilanes of formulae SiH 4 , HSiX 3 , H 2 SiX 2 , or H 3 SiX; and/or polysilanes of formulae H c Si d X e , where subscript c is an integer of 1 or more, subscript d is an integer of 2 or more, and subscript e is an integer of 0 or more, and
(2) a fifth product comprising aqueous MX a .
14. The process of claim 13 , further comprising: dehydrating the aqueous MX a .
15. The process of claim 12 , further comprising (vi) recycling the MX a in step (i).
16. The process of claim 1 , where each X is Cl.
17. The process of claim 1 , where each M is Mg.
18. The process of claim 11 , further comprising (v) reacting a halide of formula HX with the electrolysis product comprising the metal silicide, thereby preparing a reaction product comprising
(1) a product comprising one or more hydridosilanes of formulae SiH 4 , HSiX 3 , H 2 SiX 2 , and/or H 3 SiX; and
(2) a third product comprising MX a .
19. The process of claim 11 , further comprising (v) reacting the electrolysis product (or the metal silicide recovered from the electrolysis product), with an aqueous acid, thereby preparing a reaction product comprising:
(1) a fourth product comprising one or more hydridosilanes of formulae SiH 4 , HSiX 3 , H 2 SiX 2 , or H 3 SiX; and/or polysilanes of formulae H c Si d X e , where subscript c is an integer of 1 or more, subscript d is an integer of 2 or more, and subscript e is an integer of 0 or more, and
(2) a fifth product comprising aqueous MX a .
20. The process of claim 14 , further comprising (vi) recycling the MX a in step (i).