JP2019505663A - Electrochemical cell and method - Google Patents

Abstract

The electrochemical cell (10) having a first volume exposed to each surface of the anode (28) and the cathode (24) comprises a vapor inlet (5) that encloses the vapor into the first volume. Structure (4) with a solid catalyst is in the first volume.

Description

The present invention relates to an electrochemical cell, in particular an electrochemical cell for synthesizing ammonia (NH ₃ ). The present invention also relates to a method for synthesizing ammonia (NH ₃ ).

Known approaches to the requirements for ammonia synthesis include:
(1) Harbor Bosch method—pressurization and heating of N ₂ and H ₂ using an iron catalyst;
(2) Electrochemical synthesis with molten salt electrolyte and gas electrode [1-3]; and (3) Electrochemical synthesis with electrode using solid electrolyte and electrode catalyst [4-6]
Is included.
[1] Murakami T. et al. T. Nishikiori, T .; Nohira and Y.C. Ito, “Electrolytic Synthesis of Ammonia in Molten Salts Under Atmospheric Pressure”, J. Am. Amer. Chem. Soc. 125 (2), 334-335 (2003)
[2] Murakami T. et al. Et al., “Electrolytic Ammonia Synthesis from Water and Nitrogen Gas in Molten Salt Under Atmospheric Pressure”, Electrochim. Acta 50 (27), pages 5423-5426 (2005)
[3] US Pat. No. 6,881,308 (US Patent 6,881,308B2)
[4] Marnellos, G .; Zisekas, S .; And Stukides, M .; (2000), Synthesis of ammonia at atmospheric pressure with the use of solid state prototype conductors, J. Am. Catal. 193, 80-88, doi: 10.1006 / jcat. 2000.2877
[5] Lan, R.A. Irvine, J .; T.A. S. And Tao, S .; (2013), Synthesis of Ammonia directive from air and ambient at temperature and pressure, Sci. Rep. 3, 1145, doi: 10.1038 / srep01145
[6] Skodra, A .; And Stukides, M .; (2009), Electrocatalytic synthesis of ammonia from steam and nitrogen atmospheric pressure, Solid State Ionics 180, 1332-1336.
[7] Banares-Alcantra et al., “Analysis of Islanded-Ammonia-based Energy Storage Systems”, University of Oxford, September 2015.

The present invention seeks to provide an alternative method and apparatus for synthesizing ammonia from water and nitrogen (N ₂ ).

  Accordingly, the present invention provides a method and apparatus as defined in the appended claims.

  The above and further objects, features and advantages of the present invention will become more apparent from the following description of specific embodiments of the invention in connection with the appended claims.

Fig. 2 illustrates an exemplary electrochemical cell provided by an embodiment of the present invention. Figure 2 shows an enlarged three-dimensional lattice structure of a catalyst used in an embodiment of the present invention.

  The embodiment of the invention shown in FIG. 1 is an electrochemical cell 10 having three volumes 1 to 3 partitioned by a porous body.

The first volume 1 contains a nitride conductor 20 such as eutectic molten salt, for example LiCl / KCl / Li ₃ N. In use, steam (H ₂ O) is introduced into the first volume through the steam inlet 5. In order to ensure a wide distribution of inlet steam, a steam diffuser 22 can be provided.

The second volume 2 is a cathode gas electrode. Nitrogen gas (N ₂ ) 26 is introduced into the gas electrode at the surface of the porous electrode 24 opposite to the nitride conductor 20.

  The third volume 3 is an anode gas electrode. The porous electrode 28 is in contact with the nitride conductor 20 on one side.

  The DC power source 7 causes a potential difference between the two porous electrodes 24, 28, and the negative voltage −V applied to the cathode gas electrode 2 increases as the positive voltage + V applied to the anode gas electrode 3 increases. Will also increase. In general, the resulting potential difference can be in the range of 0.5V to 2V.

In use, nitrogen gas is reduced at the gas cathode 2 to nitride ions:

Inside the nitride conductor 20, the nitride ions move towards the anode under the influence of the voltage gradient between the anode and the cathode. Inside the nitride conductor 19, the nitride ions collide and react with the vapor (water) to produce ammonia:

Thus, ammonia is generated from nitrogen gas and steam. Ammonia diffuses through the nitride conductor 20 and is generated on the surface of the nitride conductor. The facility 6 can capture the generated ammonia gas and recover it. Oxide ions generated at this time move toward the anode under a potential gradient between the electrodes. This anode reaction returns electrons to the DC power source and produces oxygen into the gas anode electrode:

  The ammonia gas diffuses through the nitride conductor 20 and is captured in the facility 6. This can be dried and cleaned as needed and stored for later use.

While hydrogen (H ₂ ) was common in conventional methods and apparatus for synthesizing ammonia, the structure of the electrochemical cell of the present invention uses steam (H ₂ O) as a hydrogen source in the ammonia product. Can be used. Thus, hydrogen (H ₂₎ without requiring a separate electrolysis step for producing, or hydrogen (H ₂₎ without having to purchase and store, ammonia (NH ₃₎ electrochemically synthesized Can make the system design much simpler.

  A unique feature of the present invention is the solid catalyst 4 provided in the first volume 1.

  In an embodiment of the present invention, the solid catalyst is prepared in the form of a three-dimensional lattice structure. In another embodiment of the invention, the solid catalyst is provided in the form of a wool structure. Other structures can be used, such as spheres or other shapes made of or coated with catalyst material.

  In all of these embodiments, the catalyst is provided on a relatively open structure: a three-dimensional lattice, a wool structure, a sphere, or other shape. With respect to the catalyst, this structure can be produced from the catalyst, depending on the material selected.

The relatively open structure ensures that the fluid passes relatively freely through the catalyst structure in the immediate vicinity of the catalyst. Due to this structure, such as a three-dimensional lattice, wool, spheres, or other shapes, (b) nitride conduction so that (a) the vapor injected through the inlet structure 22 has a good opportunity to interact with the catalyst 4 The movement of ions through the body 20 is not significantly hindered by the presence of the catalyst, and (c) ammonia (NH ₃ ) produced in the nitride conductor and on the catalyst surface may rise to the collection facility 6. The catalyst can be effectively suspended in the nitride solution so that it can.

The catalyst 4 promotes the following reaction:

  The reaction rate for this reaction is improved by using a catalyst. Suitable catalyst materials include known Fe-based catalysts and Ru-based catalysts. A review on suitable catalysts can be found in reference [7].

  While the present invention has been described with particular reference to the application of synthesizing ammonia from steam and nitrogen gas, on the other hand, the electrochemical cell and synthesis method of the present invention is capable of producing other gaseous components from the first and second ionic components. It can be applied to produce a product.

Generally, means are provided for introducing the first feed material 5 (in the above example steam (H ₂ O)) into the first volume 1 and the second feed material 26 (in the above example). Means are provided for introducing nitrogen (N ₂ )) into the cathode 24. An electrolyte (in the above example in the form of a nitride conductor) is provided between the anode 28 and the cathode 24. Voltages + V and -V are applied to the anode and cathode, respectively. At the cathode, the first ion component (N ^3- in the above ^example) is generated from the second feed. The first ionic component traverses the electrolyte toward the anode under the influence of a voltage gradient between the anode and the ground electrode. Inside the electrolyte, the first ionic component collides with the first feedstock, resulting in products (ammonia (NH ₃ ) in the above example) and ionic byproducts (oxide ions (O ^{2− in the} above example)). )) Occurs. Ion by-products continue to traverse the electrolyte toward the anode under the influence of the voltage gradient between the anode and the starting electrode. When the ion by-product reaches the anode, it releases its charge and a by-product (oxygen (O ₂ ) in the above example) is generated.

  Means should also be provided to collect the product and preferably any by-products generated. Means for collecting by-products generated at the anode or cathode can also be provided.

  Although the anode is described as a gas electrode arranged to collect gaseous by-products, such an arrangement is unnecessary in electrochemical cells that are configured to perform different reactions. obtain. In such a case, it may be sufficient to provide a solid cathode, in which case the third volume 3 can be omitted.

  It will be apparent to those skilled in the art that further modifications and variations are possible within the scope of the invention as defined by the appended claims.

Claims (14)

In an electrochemical cell (10) having a first volume exposed to each surface of the anode (28) and the cathode (24) and also comprising a vapor inlet (5) for introducing vapor into the first volume. The electrochemical cell is
The facility (6) for capturing the gaseous product produced in the first volume, and the facility (6) so that the gaseous product generated on the catalyst surface is captured by the facility (6). Structure with solid catalyst in lower first volume (4)
Further comprising
The catalyst has a relatively open structure so that fluid can pass through the catalyst structure in the immediate vicinity of the catalyst so that the catalyst is effectively suspended in the first volume. Said electrochemical cell (10), characterized by being turbid. The solid catalyst is exposed relative to the first volume:
The electrochemical cell according to claim 1, comprising at least one of a Fe-based catalyst and a Ru-based catalyst.   The electrochemical cell according to claim 1, wherein the structure (4) having a solid catalyst is provided in the form of a three-dimensional lattice structure.   Electrochemical cell according to claim 1, wherein the structure (4) having a solid catalyst is provided in the form of a wool structure.   Electrochemical cell according to claim 1, wherein the structure (4) having a solid catalyst is provided in the form of a sphere or other shape made of or coated with a catalyst material.   Electrochemical cell according to any one of the preceding claims, wherein the cathode (24) is a gas electrode having a porous cathode and a second volume (2).   The electrochemical cell according to any one of claims 1 to 6, wherein the anode (28) is a gas electrode having a porous anode and a third volume (3).   Electrochemical cell according to any one of the preceding claims, wherein the steam inlet (5) comprises a steam diffuser (22). An apparatus for producing a gaseous product from first and second feed materials,
A first volume exposed for each surface of the anode (28) and the cathode (24);
The facility (6) for capturing the gaseous product produced in the first volume, and the facility (6) so that the gaseous product generated on the catalyst surface is captured by the facility (6). Structure with solid catalyst in lower first volume (4)
The catalyst has a relatively open structure so that fluid can pass through the catalyst structure in the immediate vicinity of the catalyst so that the catalyst is effectively suspended in the first volume. Clouded,
Means (5, 22) for introducing the first feed into the first volume (1);
-Means (2, 24) for introducing a second feed (26) into the first volume (1); and-an electrolyte (20) provided in the first volume.
A device comprising an electrochemical cell (10) having the following:   The apparatus of claim 9, further comprising a power supply (7) arranged to apply a positive voltage + V to the anode (28) and to apply a negative voltage -V to the cathode (24). A method for producing a gaseous product by using the apparatus of claim 9, comprising:
Applying a positive voltage + V to the anode (28);
Applying a negative voltage -V to the cathode (24);
Introducing the first feed into the first volume (1);
Introducing a second feed material into the second volume (2) exposed at the porous cathode, reacting said second feed material at the cathode, and adding the second feed material to the electrolyte in the first volume (1); Providing an ionic component;
Said method comprising the step of producing a gaseous product by reaction of the first ionic component with the first feedstock;   The method of claim 11, further comprising collecting (6) a gaseous product produced in the first volume.   13. A method according to claim 11 or 12, further comprising the step of collecting by-products generated at the anode. The first feed is steam (H ₂ O);
The first ion component is a nitride ion (N ³⁻ ),
The second feedstock is nitrogen (N ₂ ) and the gaseous product is ammonia (NH ₃ ),
14. A method according to any one of claims 11 to 13.

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