KR20240058258A - Ammonia electrolysis hydrogen production electrode and hydrogen production equipment containing thereof - Google Patents

Abstract

The ammonia decomposition hydrogen production electrode according to the present invention is characterized by sequentially including an ammonia diffusion layer, a high-density catalyst layer, and a low-density catalyst layer, thereby maximizing the active site of the catalyst layer and having the advantage of smooth supply of ammonia within the electrode.

Description

Ammonia electrolysis hydrogen production electrode and hydrogen production equipment containing the same}

The present invention relates to a hydrogen production electrode for producing hydrogen by decomposing ammonia.

Due to the development of fossil fuel-based industries, approximately 40 billion tons of carbon dioxide are being emitted annually around the world, and these carbon dioxide emissions are increasing every year. These carbon dioxide emissions are causing various climate changes, such as global warming, sea level rise, heavy rain, and drought.

Hydrogen energy has the advantages of high energy density and clean energy that does not generate pollutants, and is attracting great attention as a next-generation energy source when combined with existing renewable energy. However, the existing hydrogen production process, the steam methane reforming process, is performed at a high reaction temperature, consumes a lot of energy, and has the problem of emitting a significant amount of carbon dioxide during the reaction. Accordingly, in order to meet the increasing demand for hydrogen, a clean energy source, there is an urgent need to improve the hydrogen production process in terms of energy efficiency and environmental aspects.

The hydrogen production system through the ammonia electrolysis process has recently been attracting attention as an eco-friendly process that does not emit greenhouse gases, including carbon dioxide. The ammonia electrolysis process can produce ultra-high purity hydrogen without separate purification and separation processes, and has the advantage of low power consumption because it operates at a lower voltage than the water electrolysis process. In addition, ammonia is considered advantageous for building hydrogen technology infrastructure because it is easier to transport and store than liquid hydrogen or other hydrogen carriers.

The anode reaction that constitutes the ammonia electrolysis system consists of an ammonia oxidation reaction at the anode and a hydrogen generation reaction at the cathode. Currently, noble metals such as platinum or iridium are reported to have the highest activity as catalyst materials for the ammonia oxidation reaction. Most ammonia electrolysis systems operate in an alkaline atmosphere, and ammonia and hydroxide ions react to emit nitrogen.

The ammonia electrolysis system is advantageous in terms of energy consumption because the theoretical potential at which the oxidation reaction of ammonia occurs is very low at 0.06 V. In addition, among hydrogen production systems, a similar system has a theoretical potential of 1.23 V because the oxidation reaction in the water electrolysis process is an oxygen generation reaction, and accordingly, the driving voltage of the entire system for the oxygen generation reaction in the water electrolysis process is that of the ammonia electrolysis system. It has to be higher compared to .

However, this ammonia decomposition reaction is currently in the basic research stage, and there are problems that must be solved until commercialization. Typically, ammonia and hydroxide ions compete and are adsorbed on the surface of the ammonia oxide electrode. When the current density exceeds a certain level or the reaction time is prolonged, the adsorption of hydroxide ions becomes dominant over the adsorption of ammonia. Accordingly, the ammonia oxidation reaction no longer occurs on the electrode surface, and the oxygen generation reaction occurs by moving to a higher potential. Therefore, in the ammonia electrolysis system, electrode stability during operation at high current densities and for long periods of time is very important, and it is important to maintain the ammonia oxidation reaction to occur continuously to prevent the oxygen evolution reaction from rapidly increasing the driving voltage of the cell. Also important.

U.S. Patent Publication No. 2017-0297913 Republic of Korea Patent Publication No. 10-2022-0034652

The purpose of the present invention is to provide an ammonia decomposition hydrogen production electrode in which the ammonia oxidation reaction occurs continuously, the active site of the catalyst layer is maximized, and ammonia is smoothly supplied to the electrode.

The ammonia decomposition hydrogen production electrode according to the present invention is characterized by sequentially including an ammonia diffusion layer, a high-density catalyst layer, and a low-density catalyst layer.

The ammonia decomposition hydrogen production electrode according to an embodiment of the present invention may be characterized in that the amount of catalyst contained in the high-density catalyst layer per unit area is greater than the amount of catalyst contained in the low-density catalyst layer.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the high-density catalyst layer may be characterized as containing 2 to 8 mg of catalyst per 1 cm 2 based on a thickness of 100 ㎛.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the low-density catalyst layer may be characterized as containing 0.5 to 3 mg of catalyst per 1 cm 2 based on a thickness of 100 ㎛.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the sum of the thicknesses of the low-density catalyst layer and the high-density catalyst layer may be 30 to 450 ㎛.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the high-density catalyst layer and the low-density catalyst layer may be characterized in that they include one or more catalysts selected from ruthenium, rhodium, palladium, osmium, iridium, platinum, and alloys thereof. there is.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the ammonia decomposition hydrogen production electrode may be characterized as having a catalyst amount per unit area of 2 to 10 mg/cm2.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the ammonia diffusion layer may be characterized as having a thickness of 100 to 300 ㎛.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the high-density catalyst layer may be formed by a doctor blade method, a screen method, a decal method, a brushing method, or a slot die method.

In the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, the low-density catalyst layer may be formed by spraying or spin coating.

The present invention also provides a hydrogen production device, wherein the hydrogen production device includes an ammonia decomposition hydrogen production electrode according to an embodiment of the present invention.

The ammonia decomposition hydrogen production electrode according to the present invention is characterized by sequentially comprising an ammonia diffusion layer, a high-density catalyst layer, and a low-density catalyst layer, so that the supply of ammonia in the electrode is smooth, the oxidation reaction of ammonia occurs continuously, and the active site of the catalyst layer is It has the advantage of maximizing high hydrogen production efficiency.

Figure 1 shows the results of measuring ammonia oxidation start potential and ammonia oxidation current density according to catalyst amount and type of catalyst.
Figure 2 shows the results of analyzing the hydrogen production efficiency according to the coating method of the electrode.

Advantages and features of the embodiments of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to be understood by those skilled in the art in the technical field to which the present invention pertains. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In describing embodiments of the present invention, if a detailed description of a known function or configuration is judged to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. The terms described below are defined in consideration of functions in the embodiments of the present invention, and may vary depending on the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification.

The ammonia decomposition hydrogen production electrode according to the present invention is characterized by sequentially including an ammonia diffusion layer, a high-density catalyst layer, and a low-density catalyst layer.

The ammonia decomposition hydrogen production electrode according to the present invention has the advantage of enabling efficient and stable hydrogen production as the ammonia oxidation reaction occurs stably compared to a low-density or high-density single-layer structure catalyst based on the same catalyst content.

Specifically, when only a low-density catalyst layer is included based on the same catalyst content, the thickness of the electrode may become thick to introduce a sufficient amount of catalyst, and this increase in thickness increases the resistance of the membrane-electrode assembly and hydrogen production efficiency. losses may occur. If only a high-density catalyst layer is included, the electrochemical active area is relatively reduced, and overall performance may be reduced due to a lack of active points of the catalyst in contact with the reactants.

On the other hand, in the case of including a high-density catalyst layer and a low-density catalyst layer as in the present invention, there is an advantage that the oxidation reaction of ammonia can occur stably by securing a sufficient amount of catalyst even if catalyst poisoning occurs, and an increase in resistance due to an increase in thickness can be prevented. There is an advantage.

Specifically, the amount of catalyst contained in the high-density catalyst layer per unit area: The amount of catalyst contained in the low-density catalyst layer may be 1:9 to 9:1, and more preferably, the amount of catalyst contained in the high-density catalyst layer is 1:9 to 9:1. It may be greater than the amount of catalyst. In detail, the amount of catalyst included in the high-density catalyst layer may be 5:5 to 9:1, more specifically 6:4 to 8.5:1.5. When the catalyst content of the high-density catalyst layer is larger, not only is the initial hydrogen production efficiency the highest, but the durability of the catalyst is also the best.

The high-density catalyst layer may include 2 to 8 mg of catalyst per 1 cm2, preferably 4 to 8 mg based on a thickness of 100 ㎛, and the low-density catalyst layer may include 0.5 to 3 mg of catalyst per 1 cm2 based on a thickness of 100 ㎛. It may contain a catalyst.

As the high-density catalyst layer and the low-density catalyst layer satisfy the above-mentioned catalyst density, in the case of the high-density catalyst layer, a sufficient amount of catalyst can be secured while preventing ammonia diffusion reduction due to excessively high density, and in the case of the low-density catalyst layer, durability is increased due to the excessively low catalyst density. It is possible to prevent a rapid decline in

The sum of the thicknesses of the high-density catalyst layer and the low-density catalyst layer may be 30 to 450 ㎛, more specifically 50 to 350 ㎛. If the overall thickness of the catalyst layer is thin, it may be difficult to secure a sufficient amount of catalyst, and if the overall thickness of the catalyst layer is thick, Reduced ammonia diffusion and increased resistance may occur, reducing hydrogen production efficiency.

The high-density catalyst layer and the low-density catalyst layer may include a platinum group catalyst, and may specifically include one or two or more selected from ruthenium, rhodium, palladium, osmium, iridium, platinum, and alloys thereof.

The ammonia decomposition hydrogen production electrode according to an embodiment of the present invention includes the composite structure of the low-density catalyst layer and the high-density catalyst layer described above, and the average catalyst amount per unit area may be 2 to 10 mg/cm2, preferably 3 to 8 mg/cm2. there is. If the amount of catalyst per unit area is small, it is difficult to exhibit sufficient catalytic activity and durability may decrease, and if the amount of catalyst per unit area is large, the overall thickness may become thick and resistance may increase.

The high-density catalyst layer can be used without limitation as long as it is a method of forming a coating layer that satisfies the above-mentioned catalyst density. Specifically, the high-density catalyst layer may be formed by a high-viscosity paste coating method. Specifically, the high-viscosity paste coating method may use a doctor blade method, a screen method, a decal method, a brushing method, or a slot die method.

The low-density catalyst layer may be formed by a low-viscosity ink coating method. Specifically, the low-viscosity ink coating method may use a spray method or spin coating method.

The high-density catalyst layer may be formed by applying a catalyst paste containing catalyst particles as described above. Specifically, the paste may have a viscosity of 500 to 20,000 cP, preferably 2,000 to 15,000 cP at 25°C. If the viscosity is too low, it may be difficult to increase the density of the catalyst layer, and if the viscosity is high, it may be difficult to form a uniform, high-density catalyst layer.

The catalyst paste may include catalyst particles, an ion exchange resin, a first organic solvent, and ultrapure water, where the first organic solvent is one selected from dimethylformamide (DMF) and N-methylpyrrolidone (NMP). It may include more.

The catalyst paste may include 5 to 20 parts by weight of a first organic solvent, 0.5 to 2 parts by weight, preferably 0.7 to 1.5 parts by weight of catalyst particles, and 0.3 to 0.5 parts by weight of an ion exchange resin, based on 100 parts by weight of the ultrapure water. By satisfying this range, the contact area between the coating layer formed by the catalyst paste and ammonia can be secured and hydrogen production efficiency can be improved.

More preferably, the weight ratio of the catalyst particles: ion exchange resin may be 1:0.2 to 0.6, preferably 1:0.3 to 0.5. By satisfying this range, a certain ratio of catalyst content can be maintained in the coating layer, and the catalyst and ammonia can be maintained at a certain rate. The contact ratio can be further increased.

The low-density catalyst layer may be formed by applying a catalyst ink containing catalyst particles as described above. In this case, the thickness and catalyst content of the low-density catalyst layer can be controlled by repeating the application step. Specifically, the catalyst ink may have a viscosity of 1 to 100 cP, preferably 10 to 90 cP, based on 25°C. If the viscosity is low, a problem may arise in which the coating step must be repeated too many times, and if the viscosity is high, ammonia may be used. The contact area with is lowered, which may reduce hydrogen production efficiency.

The catalyst ink may include catalyst particles, an ion exchange resin, a second organic solvent, and ultrapure water. In this case, the second organic solvent may be a low molecular weight alcohol such as methanol, ethanol, and isopropyl alcohol.

The catalyst ink may include 5 to 20 parts by weight of a second organic solvent, 0.5 to 2 parts by weight, preferably 0.7 to 1.5 parts by weight of catalyst particles, and 0.05 to 0.3 parts by weight of an ion exchange resin, based on 100 parts by weight of the ultrapure water. Within this range, excellent hydrogen production efficiency can be secured while ensuring the durability of the low-density catalyst layer.

More preferably, the weight ratio of the catalyst particles: ion exchange resin may be 1:0.05 to 0.4, preferably 1:0.1 to 0.3. If this range is satisfied, the ion exchange resin may be added in an excessively small amount, causing a sharp decrease in the durability of the coating layer. , it is possible to prevent the problem of adding too much ion exchange resin to increase the viscosity of the ink and increase the density of the catalyst layer.

The ion exchange resin used in the catalyst paste and catalyst ink can be a cation exchange resin or an anion exchange resin. When using a powdered ion exchange resin, a catalyst paste or catalyst ink can be prepared by mixing in the above-mentioned ratio, When using an ion exchange resin dispersed in a solution, the composition ratio of the catalyst paste and ink can be adjusted by considering the content of the ion exchange resin.

In the ammonia decomposition hydrogen production electrode according to the present invention, the ammonia diffusion layer mechanically supports the electrode for the ammonia oxidation reaction and can serve as a passage through which liquid ammonia can be supplied to the catalyst layer. Specifically, the ammonia diffusion layer may use carbon paper, carbon fiber, porous metal, or alloy. At this time, the alloy may be SUS or STS, but the present invention is not limited thereto.

The ammonia diffusion layer may have a thickness of 100 to 300 ㎛, preferably 120 to 270 ㎛. If the ammonia diffusion layer is thin, it may not sufficiently support the catalyst layer and durability may be reduced. If the ammonia diffusion layer is thick, ammonia may be supplied. This may not be smooth and may cause a decrease in catalytic activity.

The present invention also provides a hydrogen production device, and the hydrogen production device according to the present invention may include an ammonia decomposition hydrogen production electrode according to an embodiment of the present invention. By including the ammonia decomposition hydrogen production electrode according to an embodiment of the present invention, there is an advantage of showing high hydrogen production efficiency and having excellent durability compared to the case of including electrodes with other catalyst structures.

Hereinafter, the present invention will be described in detail by examples and comparative examples. The examples below are only intended to aid understanding of the present invention, and the scope of the present invention is not limited by the examples below.

Comparison of activity according to catalyst amount per unit area and type of catalyst

Electrodes were manufactured by varying the electrode structure, catalyst amount, and type of catalyst, as shown in Table 1 below.

Specifically, the high-density catalyst layer is prepared by mixing 10 parts by weight of DMF with 100 parts by weight of ultrapure water to prepare a mixed solvent, and then mixing 1 part by weight of catalyst particles and 0.4 parts by weight of ion exchange resin powder with 100 parts by weight of ultrapure water into the prepared mixed solvent. A catalyst paste was prepared. The viscosity of the prepared paste was about 10,000 cP at 25°C, and the paste was coated at a speed of 1 cm per second using the doctor blade method to form a high-density catalyst layer.

The low-density catalyst layer is prepared by mixing 10 parts by weight of ethanol with 100 parts by weight of ultrapure water to prepare a mixed solvent, and then mixing 1 part by weight of catalyst particles and 0.2 parts by weight of ion exchange resin with 100 parts by weight of ultrapure water into the mixed solvent to adjust the viscosity at 25°C. A catalyst ink with a density of about 60 cP was prepared, and the prepared catalyst ink was spray coated dozens of times to secure the thickness of the low-density catalyst layer.

An ammonia oxidation reaction was performed on the prepared electrode in an electrochemical reactor containing 200 ml of electrolyte. The electrolyte used was a mixed solution of 1 M ammonia and 1 M KOH, and argon gas was injected into the electrolyte to prevent other side reactions from occurring. In addition, the electrolyte temperature was maintained at 25°C, and each electrode in Table 1 was used as a working electrode, and a three-electrode evaluation system was used with Hg/HgO as the reference electrode and platinum gauze as the counter electrode. The current density was measured in the potential range between RHE from 0 V to 1.0 V, and the starting potential and current density of the ammonia oxidation reaction peak were compared. Figure 1 shows the results of measuring the catalytic activity of the electrodes in Table 1. The scan speed of the graph is 20 mV/s, and the current density of the reaction is normalized based on the A-1 electrode and shown in Figure 1. In addition, the platinum-palladium catalyst or the platinum-iridium catalyst in Table 1 used an alloy prepared by mixing platinum and palladium or iridium in a 1:1 ratio by weight.

Manufacturing example Catalyst amount (mg/㎠) electrode structure Catalyst type A-1 2 low density catalyst layer platinum catalyst A-2 2 low density catalyst layer iridium catalyst A-3 2 low density catalyst layer Platinum-palladium alloy catalyst A-4 2 low density catalyst layer Platinum-iridium alloy catalyst B 4 low density catalyst layer Platinum-iridium alloy catalyst C 5 High-density catalyst layer Platinum-iridium alloy catalyst D 6 low density catalyst layer Platinum-iridium alloy catalyst E 8 High-density catalyst layer Platinum-iridium alloy catalyst

Referring to Figure 1, the A-1 electrode using a platinum catalyst showed an ammonia oxidation current density that was about 1.5 to 2 times higher than that of the A-2, A-3, and A-4 electrodes using other catalyst materials. However, unlike electrodes A-2, A-3, and A-4 and B, C, D, and E, which have similar ammonia oxidation start potentials, it requires the highest start potential, which is disadvantageous in starting the reaction.

In addition, comparing the ammonia oxidation start potential and maximum current density of electrodes A-4, B, C, D, and E, it can be seen that electrode C, which has a catalyst density of 5 mg/cm2, shows the highest current density.

Comparison of hydrogen production efficiency according to catalyst structure

As shown in Table 2 below, single cell operation and hydrogen production of the composite structure ammonia electrode were evaluated. In each production example, a platinum-iridium electrode for ammonia oxidation with a catalyst amount of 5 mg/cm2 per unit area was used. Preparation Example 1 (Case 1) is an electrode composed of a low-density catalyst layer using a low-viscosity ink spray coating method, and Preparation Example 4 (Case 4) is an electrode composed of a high-density catalyst layer using a high-viscosity paste coating method. In the case of Preparation Examples 2 and 3, the electrode forms a composite structure of a low-density catalyst layer and a high-density catalyst layer using a low-viscosity ink spray coating method and a high-viscosity paste coating method, and in Preparation Example 2 (case 2), the low-density catalyst layer: the catalyst of the high-density catalyst layer. The content ratio is 4:1, and in Preparation Example 3 (case 3), the catalyst content ratio of the low-density catalyst layer:high-density catalyst layer is 1:4.

Manufacturing example Electrode coating method
(Catalyst amount ratio) Catalyst amount per unit area (mg/㎠) electrode thickness
(㎛) Catalyst layer thickness (㎛) Unit area catalyst amount per 100 μm thickness
(㎎/㎠) One Low viscosity ink injection 5 465 275 1.82 2 Low viscosity ink injection + high viscosity paste
(4:1) 5 428 238 2.10 3 Low viscosity ink injection + high viscosity paste
(1:4) 5 300 110 4.55 4 high viscosity paste 5 280 90 5.56

A membrane-electrode assembly was constructed using the electrodes manufactured in each preparation example. The electrode for the ammonia oxidation reaction was the electrode prepared in each preparation example, and the electrode for hydrogen generation, which is a companion reaction, was used as a hydrogen generation electrode coated with 2 mg/cm2 of a platinum catalyst. An anion exchange foil was used as the membrane, and a 1M KOH mixed solution containing 1M NH3 based on the anode was used as the electrolyte. A constant current density experiment was performed with the manufactured ammonia decomposition device, and the current density value was 100 mA/cm2 and the electrode area was 25 cm2.

Figure 2 shows the results of ammonia electrolysis and hydrogen production evaluation using a composite structure ammonia oxidation electrode according to a production example of the present invention. In the case of Preparation Example 1, which included only a low-density catalyst layer, hydrogen production was less than about 60% of the initial performance after 10 minutes of operation time. Additionally, after 30 minutes, almost no hydrogen production was achieved through ammonia decomposition. This rapid decrease in hydrogen production performance can be seen as a result of high resistance and few active sites due to the thick catalyst thickness of the low-density catalyst layer. In the case of Sample 4, which only contained a high-density catalyst layer, the initial performance of the electrode was higher than that of Sample 1, and showed relatively stable hydrogen production until the first 30 minutes. However, after 60 minutes, hydrogen production was only about 50% of the initial performance, and the pore structure was not developed in the electrode composed of only a high-density catalyst layer, so ammonia was not supplied smoothly, resulting in a gradual decrease in performance in the mass transfer area. It is believed that a decline has occurred.

It can be confirmed that Samples 2 and 3, which have a composite electrode structure according to the present invention, show stable hydrogen production compared to Preparation Examples 1 and 4. Among them, it can be seen that Preparation Example 3, in which the ratio of the low-density catalyst layer and the high-density catalyst layer is 1:4, is excellent in terms of both electrode performance and stability.

Specifically, based on the initial production volume, the hydrogen production of Preparation Example 3 is the highest, and compared to the hydrogen production of Preparation Example 3, it is 87% or less in Preparation Example 1, 98% or less in Preparation Example 2, and 98% or less in Preparation Example 4. It can be confirmed that hydrogen production is less than 92%. In addition, after 30 minutes, when using the electrode of Preparation Example 3, hydrogen production is maintained at 95% or more compared to the initial production, whereas in Preparation Example 1, hydrogen production decreases to 12% or less, and in Preparation Example 2, It showed a level of 85 to 90%, and in the case of Preparation Example 4, it can be confirmed that hydrogen production was less than 87%. In addition, when using the electrode of Preparation Example 3, it can be confirmed that hydrogen production of more than 95% is maintained even after 60 minutes.

Claims (11)

An ammonia decomposition hydrogen production electrode comprising an ammonia diffusion layer, a high-density catalyst layer, and a low-density catalyst layer in that order.
According to clause 1,
An ammonia decomposition hydrogen production electrode, characterized in that the amount of catalyst contained in the high-density catalyst layer per unit area is greater than the amount of catalyst contained in the low-density catalyst layer.
According to clause 1,
The high-density catalyst layer is an ammonia decomposition hydrogen production electrode, characterized in that it contains 2 to 8 mg of catalyst per 1 cm 2 based on a thickness of 100 ㎛.
According to clause 1,
The low-density catalyst layer is an ammonia decomposition hydrogen production electrode, characterized in that it contains 0.5 to 3 mg of catalyst per 1 cm 2 based on a thickness of 100 ㎛.
According to clause 1,
An ammonia decomposition hydrogen production electrode, characterized in that the sum of the thicknesses of the low-density catalyst layer and the high-density catalyst layer is 30 to 450 ㎛.
According to clause 1,
An ammonia decomposition hydrogen production electrode, wherein the high-density catalyst layer and the low-density catalyst layer include one or more catalysts selected from ruthenium, rhodium, palladium, osmium, iridium, platinum, and alloys thereof.
According to clause 1,
The ammonia decomposition hydrogen production electrode is an ammonia decomposition hydrogen production electrode, characterized in that the catalyst amount per unit area is 2 to 10 mg/cm2.
According to clause 1,
An ammonia decomposition hydrogen production electrode, characterized in that the ammonia diffusion layer has a thickness of 100 to 300 ㎛.
According to clause 1,
An ammonia decomposition hydrogen production electrode, wherein the high-density catalyst layer is formed by a doctor blade method, screen method, decal method, brushing method, or slot die method.
According to clause 1,
An ammonia decomposition hydrogen production electrode, wherein the low-density catalyst layer is formed by spraying or spin coating.
A hydrogen production device comprising the ammonia decomposition hydrogen production electrode of any one of claims 1 to 10.