Processes utilising selectively permeable membranes

1. A process for synthesis of a product by reaction of at least a first reactant comprising a hydrogen species with a second reactant, the process comprising:

(i) providing a hydrogen species selectively permeable solid membrane (HSPM) having a hydrogen species receiving side and a product synthesis side;

(ii) providing a hydrogen species source at the hydrogen species receiving side;

(iii) providing a second reactant source at the product synthesis side;

(iv) providing a concentration gradient or a partial pressure differential of the hydrogen species source across the HSPM such that the concentration of hydrogen is lower on the product synthesis side than on the hydrogen species receiving side to thereby effect migration of the hydrogen species through the HSPM for reaction with the second reactant at or near the surface of the product synthesis side;

wherein at least the product synthesis side of the HSPM has a surface modification comprising a layer that is porous to the second reactant for promoting a reaction within the layer between the first and second reactants to form the product, and wherein the layer contains a plurality of triple phase reactive sites provided by a roughened surface, a metal species and a catalyst, the metal species and the catalyst being provided in a composition that is interspersed with the roughened surface.

2. The process of claim 1 , wherein the roughened surface is an outer layer of the HSPM or a layer deposited on the HSPM, the roughened surface comprising a hydrogen species permeable metal, metal alloy, cermet or metal oxide thereof.

3. The process of claim 1 , wherein the roughened surface is formed from a hydrogen permeable material selected from the group consisting of palladium, titanium nickel, an alloy of palladium, titanium, vanadium, zirconium, niobium, tantalum, or alloys of one or more from this group with silver, copper, chromium, iron, nickel or cobalt, and a cermet thereof.

4. The process of claim 1 , wherein the roughened surface is a palladium sputtered surface.

5. The process of claim 1 , wherein the metal species is a hydrogen species permeable metal, metal alloy, cermet or metal oxide thereof.

6. The process of claim 1 , wherein the HSPM is formed from a hydrogen permeable material selected from the group consisting of palladium, titanium and nickel, an alloy of palladium, titanium and nickel, and a cermet thereof.

7. The process of claim 1 , wherein the HSPM is a hydrogen permeable palladium membrane.

8. The process of claim 1 , wherein the second reactant source is a nitrogen species source and the process is for synthesizing ammonia.

9. The process of claim 1 , wherein the catalyst is an ammonia synthesis catalyst comprising an iron oxide based catalyst.

10. A hydrogen species selectively permeable solid membrane (HSPM) formed from a hydrogen permeable material selected from the group consisting of palladium, titanium and nickel, an alloy of palladium, titanium, vanadium, zirconium, niobium, tantalum or alloys of one or more from this group with silver, copper, chromium, iron, nickel or cobalt, and a cermet thereof, wherein at least one side of the membrane, or portion thereof, comprises a surface modification comprising a layer that is porous and contains within the layer a plurality of triple phase reactive sites provided by a roughened surface, a metal species and a catalyst, the metal species and the catalyst being provided in a composition that is interspersed with the roughened surface.

11. The membrane of claim 10 , wherein the roughened surface is an outer layer of the HSPM or a further layer on the HSPM, the roughened surface comprising a hydrogen species permeable metal selected from the group consisting of palladium, titanium and nickel, an alloy of palladium, titanium and nickel, and a cermet thereof.

12. The membrane of claim 10 , wherein the roughened surface is a metal sputtered surface comprising a metal selected from at least one of palladium, titanium and nickel.

13. The membrane of claim 10 , wherein the metal species is a hydrogen species permeable metal, metal alloy, cermet or metal oxide thereof.

14. The membrane of claim 13 , wherein the hydrogen species permeable metal, metal alloy, cermet or metal oxide thereof is selected from the group consisting of palladium and palladium oxide.

15. The membrane of claim 10 , wherein the HSPM is a hydrogen permeable palladium membrane.

16. The membrane of claim 10 , wherein the catalyst is an ammonia synthesis catalyst comprising an iron oxide based catalyst.

17. A reactor for synthesis of a product by reaction of at least a first reactant comprising a hydrogen species with a second reactant, the reactor comprising:

a first chamber section and a second chamber section separated by a hydrogen species selectively permeable solid membrane (HSPM) configured to provide a hydrogen species receiving side of the membrane in the first chamber section and a product synthesis side of the membrane in the second chamber section, wherein the HSPM is a surface modified membrane according to claim 10 ;

a first reactant inlet for supply of a first reactant source of a hydrogen species to the first chamber section;

a second reactant inlet for supply of a second reactant source to the second chamber section; and

a first outlet for obtaining at least a product of the reaction.

18. A system for synthesis of a product by reaction of at least a first reactant comprising a hydrogen species with a second reactant, the system comprising:

a reactor according to claim 17 ; and

a control means to control the concentration or partial pressure of hydrogen to be lower on the product synthesis side than on the hydrogen species receiving side, to thereby effect migration of the hydrogen species through the membrane to the product synthesis side for reaction with the second reactant to form the product.