Method for catalytically induced hydrolysis and recycling of metal borohydride solutions
The process for obtaining M 1 -BH 4 , the process comprising contacting M 1 -BO 2 with a metal M 2 in the presence of molecular hydrogen (H 2 ) under conditions permitting the formation of M 1 -BH 4 and M 2 -oxide, wherein the M 1 is a metal selected from column I of the periodic table of elements or alloys of metals selected from column I of the periodic table of elements and M 2 is a metal or an alloy of metals selected from column II of the periodic table of elements, provided that M 2 is not Mg and M 1 is different from M 2 .
1. A process for preparing a metal-borohydride decomposition catalyst, the process comprising depositing an alloy of formula M 3 x R onto a surface of a cathode, the deposition being carried out in a solution under induced constant cathode potential, M being a reduced metal, R being an element selected from P, B and N, and x being between 2 and 3 wherein said process comprises the steps of:
providing a solution comprising a source of M 3 metal cations and a reductant comprising the element R;
immersing the cathode, an anode and a reference electrode into the solution;
applying a current between the anode and the cathode, while inducing a constant electric potential (E) on the cathode, as measured versus the reference electrode, thereby permitting reduction of M 3 and oxidation of the reductant to obtain the deposition of M 3 x R alloy onto the cathode, the constant electric potential being lower than the reduction potential of the M 3 metal cation; and
annealing the cathode at elevated temperatures under an inert gas atmosphere.
2. The process according to claim 1 , wherein said induced constant cathode potential is lower than the reduction potential of M 3 cations.
3. The process according to claim 1 , wherein M 3 is selected from Co, Ni, Fe, and any combination thereof.
4. The process according to claim 1 , wherein the cathode is selected from a carbon-based substrate, a metallic substrate and a carbon-based substrate embedded metal.
5. The process according to claim 1 , wherein said reductant is selected from hypophosphite salts, borohydride salts, aminoboranes, hydrazine and formaldehyde, or any combination thereof.
6. The process according to claim 4 , wherein the metallic substrate is selected from a nickel plate, a nickel mesh, a cobalt plate, a cobalt mesh, a Ni/Co alloy plate, a Ni/Co alloy mesh, a stainless steel mesh, and a stainless steel mesh embedded in acetylene black.
7. The process according to claim 1 , wherein said reductant is a water-soluble salt comprising the element R.
8. The process according to claim 1 , wherein said elevated temperature is between 200 and 800° C.