AMMONIA SYNTHESIS CATALYST AND METHOD FOR ITS PRODUCTION

Claims

1. A method for synthesizing an ammonia synthesis catalyst, comprising the following steps: a) providing a transition metal precursor, preferably selected from the following: Fe, Co, Ru, Mn or V, said transition metal precursor being a metal salt and / or a metal complex, and reacting said transition metal precursor with a solution or solvent to obtain a solution containing a transition metal; b) providing a catalyst support and reacting said catalyst support with said transition metal-containing solution to form a slurry; c) drying said suspension to obtain a solid powder; d) carrying out a purification step on said solid powder to obtain a purified solid powder, said purification step comprising reducing the boron content in said solid powder; e) mixing said solid powder with a hydride to obtain said ammonia synthesis catalyst, additionally including one of the following stages: carried out before step b) introducing said transition metal-containing solution obtained in step a) into interaction with a reducing reagent; carried out before step c) introducing said suspension obtained in step b) into interaction with a reducing reagent; the said reducing reagent is sodium borohydride (NaBH4) or potassium borohydride (KBH4); the residual content of boron remaining in the said purified solid substance is not more than 0.5% by weight.

2. The method according to claim 1, wherein said metal salt and / or metal complex are selected from the following: FeCl3, Fe(NO2)3 or Fe(acac)3, or CoCl2.

3. The method according to any of the preceding paragraphs, wherein said catalyst support is one or more selected from the following: CeO2, SiO2 doped with SiO2, TiO2 doped with TiO2, ZrO2 doped with ZrO2, ZnO, Pr2O3, Nb2O5, La2O3, CaO.Al2O3, mayenite, LaCeO x , BaTiO3, BaCeO3, BaCe x Y 1-x O3, SrTiO3, CaTiO3, LaCoO3, BaZrO3, Y2C-3, LaScSi, MCM-41, silicalite-1, ZSM-5; preferably CeO2, TiO 2, doped TiO2, SiO2 or doped SiO2.

4. The method according to any of the preceding paragraphs, wherein said hydride is described by the formula X-H n , where X represents an alkali metal or alkaline earth metal, preferably Li, Na, K, Ca, Ba or Sr.

5. The method according to any of the preceding claims, wherein step e) is not carried out in an inert controlled atmosphere, which is an atmosphere that does not contain reactive gases, such as oxygen, preferably if step e) according to claim 1 is carried out in an atmosphere of ambient air.

6. The method according to any one of the preceding claims, wherein step e) is carried out by mechanically mixing said purified solid powder with said hydride in a weight ratio of 60:

40.

7. The method according to any one of the preceding claims, wherein said cleaning step carried out in step d) comprises a washing procedure.

8. The method according to claim 7, wherein said washing procedure is carried out using distilled water at a temperature in the range from 80 to 95°C, preferably at a temperature of 90°C.

9. The method according to any one of the preceding claims, wherein drying said suspension carried out in step c) comprises the step of filtering said suspension with a membrane having a pore size in the range of 0.10 to 0.40 μm, preferably in the range of 0.20 to 0.30 μm or even more preferably equal to 0.22 μm or about 0.22 μm.

10. The method according to claim 1, wherein said residual boron content is from 0 to 0.5 wt.% or from 0.01 to 0.5 wt.%, or from 0.1 to 0.5 wt.%.

11. The method according to item 1, comprising the steps of: a) providing a salt and / or complex of a transition metal selected from the following: Fe, Co, Ru, Mn, V and mixtures thereof, preferably Fe and / or Co, and introducing said salt and / or complex into reaction with an aqueous solvent to obtain a solution containing the transition metal; preferably, said salt and / or complex is selected from the following: FeCl3, Fe(NO3)3, Fe(acac)3 or CoCl2; b) providing a catalyst support and reacting said catalyst support with said transition metal-containing solution to form a slurry; said catalyst support is selected from the following: CeO2, SiO2 doped with SiO2, TiO2 doped with TiO2, ZrO2 doped with ZrO2, ZnO, Pr2O3, Nb2O5, La2O3, СаО⋅Al2O3, mayenite, LaCeO x , BaTiO3, ВаСеО3, BaCe x Y 1-x O3, SrTiO3, CaTiO3, LaCoO3, BaZrO3, Y2O3, LaScSi, MCM-41, silicalite-1, ZSM-5 and their mixtures; preferably, said catalyst support is selected from the following: CeO2, SiO2 doped with SiO2, TiO2 doped with TiO2 and mixtures thereof; c) drying the said suspension by filtration through a membrane to obtain a solid powder; d) carrying out a purification step on said solid powder, preferably carrying out at least one washing step, to obtain a purified solid powder; e) mechanically mixing said purified solid powder with an alkali metal or alkaline earth metal hydride in an ambient air atmosphere to obtain said ammonia synthesis catalyst, wherein said transition metal is in the form of nanoparticles.

12. An ammonia synthesis catalyst obtained by the method according to any of paragraphs 1-11.

13. Use of an ammonia synthesis catalyst for synthesizing ammonia, said ammonia synthesis catalyst comprising a transition metal, a catalyst support, and a hydride, wherein: said transition metal is preferably selected from the following: Fe, Co, Ru, Mn or V; said catalyst support is one or more selected from the following: CeO2, SiO2 doped with SiO2, TiO2 doped with TiO2, ZrO2 doped with ZrO2, ZnO, Pr2O3, Nb2Os, La2O3, CaO⋅Al2O3, mayenite, LaCeO x , BaTiO3, ВаСеО3, BaCe x Y 1-xO3, SrTiO3, CaTiO3, LaCoO3, BaZrO3, Y2O3, LaScSi, MCM-41, silicalite-1, ZSM-5; the said hydride is described by the following formula X-H n , where X represents Li, Na, K, Ca, Ba, or Sr.

14. The use according to claim 13, wherein said transition metal consists of nanoparticles that are dispersed and located on said catalyst support.

15. The use according to claim 13 or 14, wherein said catalyst support is CeO2, TiO2, doped TiO2, SiO2 or doped SiO2.