SYSTEM AND METHOD FOR HYDROGEN PRODUCTION BY DEHYDROGENATION OF FORMIC ACID

Abstract

The system includes a reactor vessel having a reactor space bound by a reactor wall. The reactor vessel is arranged for holding a mixture of a catalyst and formic acid in the reactor space. The reactor vessel includes a mixture inflow opening for allowing the mixture to enter the reactor space and a mixture outflow opening for allowing said mixture to exit the reactor space, and a gas outflow opening for allowing hydrogen originating from the mixture to exit the reactor space. A method for hydrogen production includes: providing the formic acid and the catalyst into the reactor space; withdrawing the mixture from the reactor space; heating and/or cooling the mixture to a predetermined temperature range outside the reactor space; and introducing the heated and/or cooled mixture into the reactor space in a predetermined direction having a tangential component arranged for stirring said mixture in the reactor space.

Claims

1. A system for hydrogen production by dehydrogenation of formic acid, said system comprising: a reactor vessel comprising a reactor space bound by a reactor wall, wherein said reactor vessel is arranged for holding a mixture of a catalyst and said formic acid in said reactor space, said reactor vessel further comprising a mixture inflow opening for allowing said mixture to enter, via said mixture inflow opening, said reactor space and a mixture outflow opening for allowing said mixture to exit, via said mixture outflow opening, said reactor space, and a gas outflow opening for allowing hydrogen originating from said mixture, via said gas outflow opening, to exit said reactor space; an inflow conduit, communicatively coupled for fluid flow, via said mixture inflow opening, to said reactor space, wherein said inflow conduit is arranged such that said mixture, in use, is introduced in said reactor space, via said mixture inflow opening, in a predetermined direction having a tangential component arranged for stirring, in use, said mixture in said reactor space; a pump, communicatively coupled for fluid flow, via said mixture inflow opening and said mixture outflow opening, to said reactor space, wherein said pump is arranged for withdrawing, via said mixture outlet opening, said mixture from said reactor space and introducing, via said inflow conduit, said mixture into said reactor space; and a temperature control arrangement, communicatively coupled for fluid flow to said pump, wherein said temperature control arrangement is arranged outside the reactor space for heating and/or cooling, in use, said mixture withdrawn from said reactor space to a predetermined temperature range before introducing, via said inflow conduit, said mixture into said reactor space.

2. The system according to claim 1, wherein said pump is arranged for displacing a two and/or three phase medium.

3. The system according to claim 1, wherein said reactor wall comprises a polymer.

4. The system according claim 1, wherein said reactor wall comprises a coating arranged for thermally insulating said reactor vessel and/or shielding said mixture from predetermined materials.

5. The system according to claim 1, wherein said reactor wall comprises replaceable wall elements arranged for realising a locally reinforced surface.

6. The system according to claim 1, wherein said reactor vessel or said inflow conduit is provided with a further inflow opening arranged for introducing said formic acid in said reactor vessel.

7. The system according to claim 1, wherein said reactor vessel comprises an upper side wall, wherein said upper side wall at least partly bounds said reactor space at an upper side thereof, wherein said upper side wall is provided with said gas outflow opening for allowing hydrogen originating from said mixture to exit, via said gas outflow opening, said reactor space.

8. The system according to claim 1, wherein said reactor vessel comprises a lower side wall, wherein said lower side wall at least partly bounds said reactor space at a lower side thereof, wherein said mixture outflow opening is provided in said lower side wall.

9. The system according to claim 8, wherein said lower side wall partly bounds said reactor space at a bottom side thereof, and wherein said mixture outflow opening is provided in a centre part of said bottom side.

10. The system according to claim 1, wherein said reactor vessel is free from a mechanical stirrer.

11. The system according to claim 1, wherein said pump is coupled to said mixture inflow opening via said temperature control arrangement for heating and/or cooling said mixture, in use by said temperature control arrangement, after said mixture has passed said pump.

12. The system according to claim 1, wherein said system further comprises a stationary flow organ arranged in said reactor space for disturbing a flow of stirring, in use, induced by introduction of said mixture in said reactor space via said inflow conduit, in said reactor space.

13. The system according to claim 1, wherein said pump is positioned lower than said reactor space.

14. A method for hydrogen production by dehydrogenation of formic acid using a system according to claim 1, said method comprising the steps of: providing said formic acid and said catalyst into said reactor space to provide a mixture of said formic acid and said catalyst inside the reactor space; withdrawing, by said pump, said mixture of said formic acid and said catalyst from said reactor space; heating and/or cooling, by said temperature control arrangement, said mixture to said predetermined temperature range outside the reactor space; and introducing, via said inlet opening, said heated and/or cooled mixture into said reactor space in a predetermined direction having a tangential component arranged for stirring said mixture in said reactor space.

15. The method according to claim 14, wherein said catalyst comprises a complex of the formula:
M(L)n  (I) in which, M is a metal selected from Ru, Rh, Jr, Pt, Pd, and Os; n is in the range of 1-4; L is a carbene, or a ligand comprising at least one phosphorus atom, said phosphor atom being bound by a complex bond to said metal, the phosphorus ligand further comprising at least an aromatic group and a hydrophilic group, wherein, if n>1, each L may be different from another L; and wherein the complex of formula (I) optionally comprises other ligands and is provided in the form of a salt or is neutral.

16. The method according to claim 14, wherein, during said step of heating and/or cooling, said predetermined temperature range is 20-200 degrees Celcius.

17. The method according to claim 16, wherein the predetermined temperature range is 70-150 degrees Celsius.

18. The system according to claim 2, wherein said pump is a turbine pump, a centrifugal pump, or a positive displacement pump.

19. The system according to claim 3, wherein said polymer is a plastic.

20. The method of claim 15, wherein M is Ru.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0048] The present disclosure will now be explained by means of a description of a preferred embodiment of a system and a method, in which reference is made to the following schematic figures, in which:

[0049] FIG. 1: a system according to the present disclosure is shown;

[0050] FIG. 2: an element of the system from FIG. 1 is shown;

[0051] FIG. 3: a top view of an element of the system from FIG. 1 is shown;

[0052] FIG. 4: a method according to the present disclosure is shown.

DESCRIPTION OF EMBODIMENTS

[0053] System 1 is arranged for producing hydrogen by dehydrogenation of formic acid. The system 1 comprises a reactor vessel 3, an inflow conduit 13, a pump 15 and a temperature control arrangement 17. The reactor vessel 3 comprises a reactor space 5 that is bound by a reactor wall 7. The reactor wall 7 comprises a lower side wall 27 and an upper side wall 23. The upper side wall 23 is provided with a gas outflow opening 25 for allowing hydrogen originating from the mixture to exit the reactor space 5 via the gas outflow opening 25. Exiting of the hydrogen from the reactor space 5 may be prevented by a blocking arrangement 31 arranged for in a first condition of the blocking arrangement 31 allow the hydrogen originating from the reactor space 5 to pass the blocking arrangement 31 and in a second condition of the blocking arrangement 31 block exiting of hydrogen from the reactor space 5. The lower side wall 27 comprises a mixture outflow opening 11 that is provided in a centre part of a bottom side of the reactor vessel 3.

[0054] The reactor vessel 3 is arranged for holding a mixture of the catalyst and the formic acid in the reactor space 5. The reactor vessel 3 comprises a mixture inflow opening 9 for allowing the mixture to enter the reactor space 5 via the mixture inflow opening 9. In the reactor space 5 a stationary flow organ 29 is provided at or near the reactor wall 7. The flow organ 29 extends along substantially the complete height of the reactor space 5. In an embodiment of the system 1 it is conceivable that the flow organ extends only along a lower half of the height of the reactor space 5. The flow organ 29 is arranged inside the reactor space 5 at a position to alter or disturb the circulating flow of said mixture. In particular, the flow organ 29 may be arranged to restrict the laminating flow of the mixture along or near the reactor wall 7. In this way, the circulation of the mixture inside the reactor space 5 is optimised and/or a vortex formation inside the reactor space 5 is reduced or prohibited.

[0055] The reactor vessel 3 is provided with a further inflow opening 21 that is arranged for introducing the formic acid, from a storage 35, in the reactor vessel 3 for forming the mixture. The storage 35 is coupled for fluid flow to the reactor space 5 via a further pump 37. The further pump 37 is arranged for pumping the formic acid from the storage 35 into the reactor space 5.

[0056] The reactor wall 7 is comprises a plastic that is coated on a side of the plastic facing the reactor space 5 with polytetrafluoroethylene for thermally insulating the reactor vessel 13 and shielding the mixture from the plastic of the reactor wall 7 that may otherwise degrade the catalyst present in the reactor space 5. The reactor wall 7 further comprises a replaceable wall element 33. The replaceable wall element 33 comprises a metal for locally reinforcing the reactor wall 7. The replaceable wall element 33 is coated on a side of the replaceable wall element 33 facing the reactor space 5 with polytetrafluoroethylene for thermally insulating the reactor vessel 13 and shielding the mixture from the metal of the replaceable wall element 33 that may otherwise degrade the catalyst present in the reactor space 5. In an embodiment of the system 1 it is conceivable that the reactor wall is locally reinforced by a fixed wall element in addition to, or as an alternative of, the replaceable wall element 33.

[0057] The inflow conduit 13 is communicatively coupled for fluid flow, via said mixture inflow opening 9, to said reactor space 5. The inflow conduit 13 is arranged such that said mixture, in use, is introduced in said reactor space 5, via said mixture inflow opening 9, in a predetermined direction having a tangential component T for stirring 39, in use, said mixture in said reactor space 5. In other words, the mixture is introduced in a direction along the reactor wall 7, wherein said direction of introduction has the tangential component T. The predetermined direction having a tangential component T is arranged to provide or enhance a stirring flow of said mixture inside the reactor space 5 in a substantially circular direction, such as along the reactor wall 7 (As shown in FIG. 3). In this way, a stirring of said mixture through the reactor space 5 is easily obtained while maintaining a substantially uniform temperature of said mixture inside the reactor space 5. Preferably, the reactor wall 7 has an inner surface, which is substantially circular in a plane parallel to the tangential component T of predetermined direction of introducing said mixture via said mixture inflow opening into said reactor space. In particular, said inner surface may be concave curved to support the stirring movement of said mixture along the reactor wall 7.

[0058] The pump 15 is communicatively coupled for fluid flow, via the mixture inflow opening 9 and the mixture outflow opening 11, to the reactor space 5. The pump 15 is arranged for withdrawing, via the mixture outlet opening 11, the mixture from the reactor space 5 and introducing, via the inflow conduit 13 and the inflow opening 9, the mixture into the reactor space 5.

[0059] The temperature control arrangement 17 is communicatively coupled for fluid flow to said pump 15 and arranged for heating and/or cooling the mixture withdrawn from the reactor space 5. The temperature control arrangement 17 is arranged outside the reactor space 5. Preferably, the temperature control arrangement 17 is arranged downstream of the pump 15. The temperature control arrangement 17 is further arranged for cooling and/or heating a part of the mixture present in the temperature control arrangement 17 to be cooled and/or heated to a predetermined temperature in the range of 70 to 150 degrees Celcius before introducing, via the inflow conduit 13, the part of the mixture into said reactor space 5.

[0060] The system 1 comprises a control unit 41 and a measurement unit 43. The control unit 41 is communicatively coupled to said temperature control arrangement 17, the pump 15 and the measurement unit 43. The control unit 41 is arranged for controlling the temperature control arrangement 17 and the pump 15 in dependence of a temperature of the mixture, in use present in the reactor space 5 and/or the temperature control arrangement 17, measured by the measurement unit 43.

[0061] Method 101 is arranged for hydrogen production by dehydrogenation of formic acid. The method 101 comprises the step of providing 103 said formic acid and said catalyst into said reactor space 5. In an embodiment of the method 101, said providing of said formic acid may be executed in a step 103a as part of step 103 and said providing of said catalyst may be executed during a step 103b as part of step 103. In other words the formic acid and the catalyst may be provided in said reactor space 5 during different steps 103a, 103b to allow said formic acid and said catalyst to be stored separately.

[0062] The catalyst providing, during said step of providing 103, comprises a complex of the formula

M(L).sub.n  (I)

in which,
M is a metal selected from Ru, Rh, Ir, Pt, Pd, and Os, preferably Ru;
n is in the range of 1-4;
L is a carbene, or a ligand comprising at least one phosphorus atom, said phosphor atom being bound by a complex bond to said metal, the phosphorus ligand further comprising at least an aromatic group and a hydrophilic group, wherein,
if n>1, each L may be different from another L;
wherein the complex of formula (I) optionally comprises other ligands and is provided in the form of a salt or is neutral.

[0063] Method 101 further comprises a step 105 of withdrawing, by said pump 15, said provided catalyst and said formic acid from said reactor space 5. Subsequently, said mixture, withdrawn during said step 105, is heated and/or cooled, during a step 107 of heating and/or cooling, by said temperature control arrangement 17, to said predetermined temperature. During said step 107 of heating and/or cooling, said predetermined temperature is in the range of 70-150 degrees Celcius

[0064] After said heating and/or cooling during said step 107, said heated and/or cooled mixture is introduced, during a step 109 of introducing, via said inlet opening 9, into said reactor space 5. During the step 109 of introducing, the mixture is introduced into the reactor space 5 in the predetermined direction having the tangential component T arranged for stirring 39, in use, said mixture in said reactor space 5. In other words, the mixture is introduced in a direction along the reactor wall 7, wherein said direction of introduction has the tangential component T.

[0065] Method 101 comprises a step 111 of exiting hydrogen, from said reactor space 5, via said gas outflow opening 25. Method 101 may further comprise a step 113 of introducing formic acid during said step 105 of withdrawing, said step 109 of introducing.