Catalyst for decomposition of formic acid, method for decomposing formic acid, process for producing hydrogen, apparatus for producing and decomposing formic acid, and method for storing and generating hydrogen
A catalyst for the decomposition of formic acid including a dinuclear metal complex represented by a formula (1) below, a tautomer or stereoisomer thereof, or any of their salts, where M 1 and M 2 are transition metals; Ar is a ligand having aromaticity and may be unsubstituted or substituted; R 1 to R 27 are each independently a hydrogen atom, an alkyl group, or the like, or R 15 and R 16 may together form a —CH═CH—, where Hs in the —CH═CH— may be each independently replaced by an alkyl group or the like, and R 23 and R 24 may together form a —CH═CH—, where Hs in the —CH═CH— may be each independently replaced by an alkyl group or the like; L is an arbitrary ligand or is absent; and m is a positive integer, 0, or a negative integer.
1. A catalyst for decomposition of formic acid comprising a dinuclear metal complex represented by a formula (1) below, a tautomer or stereoisomer thereof, or any of their salts,
where M 1 and M 2 are transition metals and may be the same or different;
Ar is a ligand having aromaticity and may be unsubstituted or substituted by one or more substituents;
R 1 to R 5 are each independently a hydrogen atom, an alkyl group, a phenyl group, or a cyclopentadienyl group;
R 12 to R 27 are each independently a hydrogen atom, an alkyl group, a phenyl group, a nitro group, a halogen group, a sulfonic acid group (sulfo group), an amino group, a carboxylic acid group (carboxy group), a hydroxy group, or an alkoxy group, or
R 15 and R 16 may together form a —CH═CH—, that is, R 15 and R 16 may, together with a bipyridine ring to which R 15 and R 16 are bonded, form a phenanthroline ring, where Hs in the —CH═CH— may be each independently replaced by an alkyl group, a phenyl group, a nitro group, a halogen group, a sulfonic acid group (sulfo group), an amino group, a carboxylic acid group (carboxy group), a hydroxy group, or an alkoxy group, and
R 23 and R 24 may together form a —CH═CH—, that is, R 23 and R 24 may, together with a bipyridine ring to which R 23 and R 24 are bonded, form a phenanthroline ring, where Hs in the —CH═CH— may be each independently replaced by an alkyl group, a phenyl group, a nitro group, a halogen group, a sulfonic acid group (sulfo group), an amino group, a carboxylic acid group (carboxy group), a hydroxy group, or an alkoxy group;
L is an arbitrary ligand or is absent; and
m is a positive integer, 0, or a negative integer.
2. The catalyst for the decomposition of formic acid according to claim 1 , wherein in the formula (1), the one or more substituents on Ar are each independently an alkyl group, a phenyl group, or a cyclopentadienyl group.
3. The catalyst for the decomposition of formic acid according to claim 1 , wherein in the formula (1), L is a water molecule, a hydrogen atom, an alkoxide ion, a hydroxide ion, a halide ion, a carbonate ion, a trifluoromethanesulfonate ion, a sulfate ion, a nitrate ion, a formate ion, or an acetate ion or is absent.
4. The catalyst for the decomposition of formic acid according to claim 1 , wherein all of R 1 to R 5 are methyl groups.
5. The catalyst for the decomposition of formic acid according to claim 1 , wherein all of R 12 to R 27 are hydrogen atoms.
6. The catalyst for the decomposition of formic acid according to claim 1 , wherein M 1 is ruthenium, osmium, iron, manganese, chromium, cobalt, iridium, or rhodium.
7. The catalyst for the decomposition of formic acid according to claim 1 , wherein M 2 is iridium, ruthenium, rhodium, cobalt, osmium, nickel, or platinum.
8. The catalyst for the decomposition of formic acid according to claim 1 , wherein M 1 is ruthenium and M 2 is iridium.
9. The catalyst for the decomposition of formic acid according to claim 1 , wherein m is 2, 3, or 4.
10. The catalyst for the decomposition of formic acid according to claim 1 , wherein the dinuclear metal complex of the formula (1) is a dinuclear metal complex having a structure represented by a formula (6) below,
where R 6 to R 11 are each independently a hydrogen atom, an alkyl group, a phenyl group, a nitro group, a halogen group, a sulfonic acid group (sulfo group), an amino group, a carboxylic acid group (carboxy group), a hydroxy group, or an alkoxy group; and
M 1 , M 2 , R 1 to R 5 , R 12 to R 27 , L, and m are assigned the same definition as those in the formula (1).
11. The catalyst for the decomposition of formic acid according to claim 10 , wherein all of R 6 to R 27 are hydrogen atoms.
12. The catalyst for the decomposition of formic acid according to claim 11 , which is represented by a formula (7) below,
where L and m are assigned the same definition as those in the formula (6).
13. The catalyst for the decomposition of formic acid according to claim 12 , which is represented by any one of formulae (8) to (11) below.
14. A method for decomposing formic acid comprising at least one step selected from the group consisting of the steps of: allowing a solution containing the catalyst for the decomposition of formic acid according to claim 1 and formic acid to stand as it is; heating the solution; and irradiating the solution with light.
15. The method according to claim 14 , wherein the solution is an aqueous solution.
16. An apparatus for decomposing formic acid, comprising a formic acid decomposing portion for generating hydrogen (H 2 ) and carbon dioxide (CO 2 ) by decomposing formic acid and a formic acid producing portion for producing formic acid from hydrogen (H 2 ) and carbon dioxide (CO 2 ),
wherein the formic acid decomposing portion contains the catalyst for the decomposition of formic acid according to claim 1 ; and
the formic acid producing portion contains a catalyst for production of formic acid for producing formic acid by reacting hydrogen (H 2 ) with carbon Dioxide (CO 2 ).