Oxygen carrier production method, hydrogen production method, and hydrogen production device

Abstract

The present invention addresses the problem of providing a method for producing a highly active oxygen carrier at low cost, and a hydrogen production method and hydrogen production device using a highly active oxygen carrier. A method for producing an oxygen carrier according to the present invention, which is a method for producing an oxygen carrier containing an activated iron titanate containing an alkali metal titanate and iron oxide by firing a mixture of iron titanate particles and a basic component, the mixture of the iron titanate particles and the alkaline component is prepared by either physically mixing the iron titanate particles with an alkaline compound; and spraying or impregnating the iron titanate particles with an aqueous solution of an alkaline compound, and then drying the particles.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an oxygen carrier, a method for manufacturing hydrogen, and an apparatus for manufacturing hydrogen. Background Technology

[0002] Chemical looping combustion is a method of combustion in which fuel is burned without direct contact with air by using an oxygen carrier. In this method, the fuel is burned by oxygen in the oxygen carrier, and high concentrations of carbon dioxide are recovered (see, for example, Patent Document 1). Chemical looping technology is also used for fuel gasification. Such chemical looping technologies require low-cost, highly reactive oxygen carriers.

[0003] Iron oxide-based materials have long been widely used as oxygen carriers for chemical looping combustion. However, natural iron ores (hematite, magnetite, ilmenite, etc.) have low reactivity and are therefore unsuitable. As oxygen carriers containing synthetic materials, FeO / Al₂O₃-based materials can be cited as examples. Such materials are expensive and also have the disadvantage of being prone to pulverization.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent document 1: Japanese Patent Application Publication No. 2018-58002. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] There is a search for a highly active oxygen carrier that can be manufactured at low cost, but such an oxygen carrier has not yet been obtained.

[0009] Therefore, the object of the present invention is to provide a method for manufacturing a highly active oxygen carrier at low cost, as well as a hydrogen manufacturing method and apparatus using a highly active oxygen carrier.

[0010] Methods for solving problems

[0011] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that alkaline components such as potassium have a tendency to preferentially combine with titanium oxide in ferric titanate at high temperature to form alkali metal titanates, thereby releasing highly dispersed iron oxide. Based on this, the inventors reacted the mixture of ferric titanate and alkaline components at high temperature to form high-melting-point alkali metal titanates in ferric titanate, thereby releasing highly dispersed iron oxide, thus completing the present invention.

[0012] This invention relates to a method for manufacturing an oxygen carrier, which involves calcining a mixture of ferric titanate particles and an alkaline component to produce an activated ferric titanate oxygen carrier containing alkali metal titanate and iron oxide. The method is characterized in that the mixture of ferric titanate particles and the alkaline component is prepared by any of the following methods: physically mixing the ferric titanate particles with an alkaline compound; and spraying or impregnating the ferric titanate particles with an aqueous solution of the alkaline compound, followed by drying.

[0013] In addition, the present invention relates to a method for manufacturing an oxygen carrier, which is a method for producing an activated iron titanate containing alkali metal titanate and iron oxide by calcining a mixture of iron titanate particles and an alkaline component, characterized in that the iron titanate particles are brought into contact with the alkaline component in a high-temperature reaction apparatus.

[0014] Furthermore, the present invention relates to a method for producing hydrogen, characterized by comprising the following steps: an air combustion step in which fuel is burned in the presence of iron titanate particles; a fuel reaction activation step in which the iron titanate particles are contacted with an alkaline component to generate activated iron titanate containing alkali metal titanate and iron oxide; and a hydrogen generation step in which hydrogen is generated by reacting the iron oxide generated in the above-mentioned fuel reaction activation step with water vapor.

[0015] Furthermore, the present invention also relates to a hydrogen production apparatus, characterized in that it comprises: an air combustion tower for burning fuel in the presence of iron titanate particles; a fuel reaction activation tower for contacting iron titanate particles with an alkaline component to generate activated iron titanate containing alkali metal titanate and iron oxide; and a hydrogen generation tower for generating hydrogen through the reaction of iron oxide generated in the above-mentioned fuel reaction activation tower with water vapor.

[0016] The effects of the invention

[0017] According to the present invention, a method for manufacturing a highly active oxygen carrier at low cost, as well as a hydrogen manufacturing method and apparatus using a highly active oxygen carrier, are provided. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the hydrogen production method of the present invention.

[0019] Figure 2 This is a graph showing the results of the equilibrium composition calculation.

[0020] Figure 3 This is a graph showing the results of the equilibrium composition calculation.

[0021] Figure 4 This is a graph showing the results of the equilibrium composition calculation.

[0022] Figure 5This is a graph showing the results of the equilibrium composition calculation.

[0023] Figure 6 This is the XRD pattern of activated ilmenite.

[0024] Figure 7 This is the XRD pattern of activated ilmenite.

[0025] Figure 8 This is the XRD pattern of activated ilmenite.

[0026] Figure 9 This is a schematic diagram of the apparatus used in the redox reaction of activating ilmenite.

[0027] Figure 10 This is a graph showing the rate of mass change in the reduction reaction of activated ilmenite.

[0028] Figure 11 This is a graph showing the rate of mass change during the steam oxidation reaction of activated ilmenite.

[0029] Figure 12 This is a graph showing the effect of potassium loading on the reductive reactivity of activated ilmenite.

[0030] Figure 13 This is a graph showing the effect of the (K / Ti) ratio on the reduction reactivity of activated ilmenite.

[0031] Figure 14 This is a graph showing the effect of potassium loading on the steam oxidation reactivity of activated ilmenite. Detailed Implementation

[0032] The following describes the method for manufacturing the oxygen carrier, the method for manufacturing hydrogen, and the apparatus for manufacturing hydrogen according to the present invention. In this invention, the oxygen carrier is manufactured by activating ferric titanate particles through a reaction with an alkaline component. Natural ferric titanate (ilmenite) is known as a low-cost, natural sandy mineral. The titanium oxide content in the ferric titanate is not particularly limited, but it is preferable that the titanium oxide content is more than half. It should be noted that the alkaline component refers to potassium, sodium, etc.

[0033] In ferrous titanate, ilmenite represented by Fe2TiO5 is preferred. When a mixture of ilmenite and alkali is calcined, as shown in formula (1) below, a high-melting-point potassium titanate is formed, releasing harmless iron oxide. In this specification, the combination of potassium titanate (K2TiO3) and iron oxide (hematite: Fe2O3) is referred to as activated ilmenite. Activated ilmenite is useful as a highly active oxygen carrier. Since ilmenite is a natural sandy ore, a highly active oxygen carrier can be manufactured at low cost.

[0034]

[0035] As ilmenite, particles with a diameter of approximately 10–500 μm can be used. Ilmenite particles can be physically mixed with an alkaline compound to prepare a mixture, for example. Specifically, examples of alkaline compounds include potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate, and sodium hydroxide. Approximately 10 parts by mass of an alkaline compound is preferred relative to 100 parts by mass of ilmenite particles. For example, the desired mixture can be obtained by stirring with potassium carbonate or similar materials for approximately 1–10 minutes.

[0036] A mixture of ilmenite particles and alkali can also be prepared by spraying or impregnating with an aqueous solution of an alkaline compound. For spraying, for example, potassium carbonate is dissolved in pure water to prepare an aqueous solution with a concentration of 50–100% by mass, and the resulting aqueous solution is sprayed onto the ilmenite particles. Spraying the aqueous solution is preferably performed while the ilmenite particles are agitated. For impregnation, for example, potassium carbonate is dissolved in pure water to prepare an aqueous solution with a concentration of 5–10% by mass. The ilmenite particles are stirred in the aqueous solution for approximately 30–60 minutes to allow the alkaline component to impregnate the ilmenite particles.

[0037] The target mixture can be obtained by drying ilmenite particles sprayed or impregnated with an aqueous solution of an alkaline compound at 100–120°C for about 30–60 minutes using a dryer or similar equipment.

[0038] The mixture is placed in an alumina container and fired at, for example, 800–980°C for approximately 0.5–3 hours, thereby generating alkali metal titanates and releasing iron oxide. The firing temperature is preferably 800–950°C, more preferably 900–920°C. The firing time can be appropriately selected according to the firing temperature.

[0039] Alternatively, activated ilmenite can be produced by contacting ilmenite particles with alkaline components in a high-temperature reaction apparatus. Specifically, an alkaline compound is contained in a fluidized bed or circulating fluidized bed with ilmenite particles as the flowing medium, and the ilmenite particles react with the alkaline components in the fluidized bed reactor. The temperature of the high-temperature reaction apparatus is preferably 800–980°C. Through this reaction, as shown in formula (1) above, activated ilmenite containing alkali metal titanate and iron oxide is obtained.

[0040] Fuels containing alkaline components, such as biomass and lignite, can also be used as alkali supply sources. The fuel containing alkaline components is introduced into a fluidized bed or circulating fluidized bed with ilmenite particles as the flowing medium, causing the fuel to burn or gasify. In this case, the ilmenite also comes into contact with the alkaline compounds in the fuel, as shown in formula (1) above, resulting in activated ilmenite containing alkali metal titanates and iron oxide.

[0041] Activated ilmenite can be used as an active oxygen carrier in chemical looping combustion, gasification, and hydrogen production processes. It can also be used in steam-iron hydrogen production processes. By reducing the iron oxide released from activated ilmenite to iron, it becomes a highly dispersed iron catalyst, which can also be used in catalyst synthesis processes.

[0042] The oxygen carrier manufactured by the method of this invention can be used in hydrogen production. (See reference...) Figure 1 This needs to be explained.

[0043] Ilmenite particles (not shown) are contained in an air combustion tower 10 as a circulating flow medium, and air 20 is introduced. Combustion takes place in the air combustion tower 10 at a temperature above 950°C. The ilmenite particles and exhaust gas are then introduced into a fuel reaction activation tower 12 via a first cyclone separator 27. A portion of the combustion exhaust gas introduced into the first cyclone separator 27 is introduced into a second cyclone separator 28, where N221 and ash 22 are discharged.

[0044] Fuel 24, containing alkaline components, is introduced into the fuel reaction activation tower 12 and burned at a temperature of approximately 850–950°C. Titanate is generated through reaction with titanium in ilmenite. Furthermore, iron oxide in the ilmenite is reduced to obtain activated ilmenite containing potassium titanate and iron oxide. As fuel 24 containing alkaline components, alkaline compounds can be supplied in combination with the fuel. Alternatively, fuels containing alkaline components, such as lignite and biomass, can also be supplied as fuel 24 containing alkaline components.

[0045] The reaction within the fuel reaction activation tower 12 can be represented, for example, by the following formula.

[0046]

[0047] CO223 generated by the reaction is discharged from the fuel reaction activation tower 12, and activated ilmenite 25 is introduced into the hydrogen generation tower 14. Water vapor is introduced into the hydrogen generation tower 14, although not shown. Hydrogen is generated within the hydrogen generation tower 14 through the reaction shown below.

[0048]

[0049] The H226 generated here is discharged from hydrogen generation tower 14.

[0050] Because the iron oxide released during the formation of potassium titanate is highly reactive, it can promote the reduction reaction of iron oxide in the fuel reaction activation tower 12. For the same reason, it can also promote the hydrogen generation reaction in the hydrogen generation tower 14. The activated ilmenite produced by the method of the present invention has high reactivity and can promote oxidation / reduction / hydrogen generation reactions, thus it can be effectively used for hydrogen production.

[0051] In the above example, a method for producing hydrogen using activated ilmenite produced within a circulating fluidized bed system was described, but it is also possible to produce hydrogen by reacting activated ilmenite produced outside the system with water vapor.

[0052] Example

[0053] The present invention will be specifically described below based on embodiments, but these embodiments do not limit the purpose of the invention. Furthermore, the present invention is not limited to these embodiments.

[0054] 1. Equilibrium composition calculation

[0055] Using commercially available chemical equilibrium calculation software (HSC Chemistry), equilibrium calculations were performed on the formation of potassium titanate and sodium titanate from ilmenite and alkali. Initial conditions under oxidizing and reducing atmospheres were input, and calculation results based on Gibbs' principle (the principle of minimum free energy) were obtained.

[0056] <Conditions for the formation of potassium titanate>

[0057] Input conditions under oxidizing atmosphere

[0058] Fe2TiO5 100kmol, K2CO3 20kmol, O2 10kmol

[0059] Input conditions under reducing atmosphere

[0060] Fe2TiO5 100kmol, K2CO3 20kmol, H2 10kmol

[0061] The calculation results for the formation conditions of potassium titanate under oxidizing and reducing atmospheres are shown in the figure. Figure 2 and Figure 3 middle.

[0062] <Conditions for the formation of sodium titanate>

[0063] Input conditions under oxidizing atmosphere

[0064] Fe2TiO5 100kmol, Na2CO3 20kmol, O2 10kmol

[0065] Input conditions under reducing atmosphere

[0066] Fe2TiO5 100kmol, Na2CO3 20kmol, H2 10kmol

[0067] The calculation results for the formation conditions of sodium titanate under oxidizing and reducing atmospheres are shown in the figure. Figure 4 and Figure 5 middle.

[0068] Figure 2 , Figure 3 The study shows that, under both oxidizing and reducing atmospheres, the alkaline component selectively combines with titanium dioxide to form potassium titanate. Furthermore, Figure 4 , Figure 5 The results show that sodium titanate was generated in the high-temperature range of 600℃ to 1000℃ under either oxidizing or reducing atmosphere.

[0069] The calculation results above confirm that alkalis such as potassium have a tendency to combine with titanium oxide in ilmenite at high temperatures to form alkali metal titanates.

[0070] 2. Manufacturing of oxygen carriers

[0071] An oxygen carrier containing activated ilmenite is produced by calcining a mixture of ilmenite particles and alkaline components using the method of the present invention.

[0072] <Physical Mixing Method>

[0073] A physical mixture was prepared by mixing 20 g of ilmenite particles (average particle size: 120 μm) and 1.8 g of potassium carbonate by stirring. The resulting physical mixture was placed in an alumina container and calcined at 920 °C for 3 hours to produce activated ilmenite (potassium-loaded ilmenite) 1. The potassium loading in activated ilmenite 1 was approximately 2.0 wt%, and the molar ratio of potassium to titanium (K / Ti) was approximately 0.084.

[0074] <Immersion Mixing Method>

[0075] Dissolve 1.8 g of potassium carbonate in 20 mL of pure water to prepare a 10% (w / w) aqueous solution. Immerse 20 g of ilmenite particles (average particle size: 120 μm) in this aqueous solution for 60 minutes to allow the solution to permeate the ilmenite particles. Remove the ilmenite particles and dry them at 120 °C for approximately 60 minutes using a dryer to prepare an impregnation mixture. Place the resulting impregnation mixture in an alumina container and calcine at 920 °C for 3 hours to produce activated ilmenite (potassium-loaded ilmenite) 2. The potassium loading in activated ilmenite 2 is approximately 2.0 wt%, and the potassium to titanium molar ratio (K / Ti) is approximately 0.084.

[0076] <Spray Mixing Method>

[0077] 1.8 g of potassium carbonate was dissolved in 2.5 mL of pure water to prepare a 72% by mass aqueous solution. A spray mixture was prepared by spraying this aqueous solution onto 20 g of ilmenite particles (average particle size: 120 μm) while shaking. The resulting spray mixture was placed in an alumina container and calcined at 920 °C for 3 hours to produce activated ilmenite (potassium-loaded ilmenite) 3. The potassium loading in activated ilmenite 3 was approximately 2.0 wt%, and the molar ratio of potassium to titanium (K / Ti) was approximately 0.084.

[0078] The XRD results of the activated ilmenite 1, activated ilmenite 2, and activated ilmenite 3 are shown below. Figure 6 , Figure 7 and Figure 8 In all measurements, peaks for potassium titanate and hematite were clearly observed. This confirms the presence of potassium titanate and hematite in the activated ilmenite produced by the method of this invention.

[0079] use Figure 9 The apparatus shown was used to evaluate the reducibility and steam oxidation reactivity of activated ilmenite. Specifically, 0.05 g of activated ilmenite was placed in a container, and tests were conducted under the following conditions to investigate the rate of change in mass. For comparison, the rate of change in mass was also investigated for unactivated ilmenite (unburned ilmenite).

[0080] reduction

[0081] CO 15% / CO2 20% / Ar atmosphere at 900℃ for 30 minutes

[0082] Water vapor oxidation

[0083] 15 minutes at 900℃ in an atmosphere of 45% water vapor and Ar.

[0084] Figure 10 The figure shows the rate of mass change in the reduction reaction. Figure 11 The figure shows the mass change rate in the steam oxidation reaction. It was confirmed that the mass change rate in physical mixing (activated ilmenite 1), infiltration mixing (activated ilmenite 2), and spray mixing (activated ilmenite 3) was greater than that in ilmenite, indicating that the ilmenite had a reactivity several times higher than that in ilmenite.

[0085] Next, six types of activated ilmenite with different potassium loadings (potassium-loaded ilmenite) were prepared by spray mixing, and the effects of potassium loading on the reduction and steam oxidation reactions were investigated. The potassium loading was adjusted by varying the amount of potassium carbonate within the range of 0–3.8 wt%.

[0086] Figure 12The figure shows the change in the rate of mass change during the reduction reaction over time. It can be seen that if 0.19 wt% potassium is added, the rate of mass change increases in the initial stage of the reduction reaction, and the reactivity is improved. In this case, the molar ratio of potassium to titanium (K / Ti ratio) is 0.008. To improve the reactivity, the (K / Ti ratio) is preferably 0.008 or higher. As the potassium loading increases, the rate of mass change also tends to increase, but even with a potassium loading of 2 wt% or more, the reactivity does not significantly improve.

[0087] Figure 13 The diagram shows the relationship between the molar ratio of potassium to titanium (K / Ti ratio) in activated ilmenite and the rate of mass change. In the rate of mass change ((W3-W0) / t3), W3, W0, and t3 have the following meanings.

[0088] W3: Mass change at 3 minutes (wt%)

[0089] W0: Mass change at 0 minutes (wt%)

[0090] t3: Time at time W3 (min)

[0091] Before the K / Ti ratio reaches 0.008%, the rate of mass change increases sharply. When the K / Ti ratio exceeds 0.008%, the increase in the rate of mass change is smaller.

[0092] Figure 14 The figure shows the increase in the rate of mass change over time in the steam oxidation reaction. It can be seen that if 0.19 wt% potassium is added, the rate of mass change increases in the initial stage of the reaction, and the reactivity of the steam oxidation is improved. To further improve the reactivity of the steam oxidation, a K / Ti ratio of 0.008 or higher is preferred. As the potassium loading increases, the rate of mass change also tends to increase, but even with a potassium loading of 2 wt% or more, the reactivity does not significantly improve.

[0093] The activated ilmenite produced by the method of this invention is a highly reactive oxygen carrier with high reactivity, and therefore can be effectively used for chemical looping combustion and hydrogen production.

[0094] Explanation of symbols

[0095] 10…Air combustion tower, 12…Fuel reaction activation tower, 14…Hydrogen generation tower.

Claims

1. A method for manufacturing an oxygen carrier, comprising calcining a mixture of ferric titanate particles and an alkaline component to produce an activated ferric titanate oxygen carrier containing alkali metal titanate and iron oxide, characterized in that... The mixture of the ferric titanate particles and the alkaline component is prepared by any of the following methods: The ferric titanate particles are physically mixed with an alkaline compound; and Ferric titanate particles are sprayed or impregnated with an aqueous solution of an alkaline compound, and then dried.

2. The method for manufacturing an oxygen carrier as described in claim 1, wherein, The iron titanate is ilmenite.

3. The method for manufacturing an oxygen carrier as described in claim 1 or 2, wherein, The alkaline compound is potassium carbonate.

4. The method for manufacturing an oxygen carrier as described in claim 1 or 2, characterized in that, The firing process is carried out at 800℃~980℃ for 0.5 hours to 3 hours.

5. A method for manufacturing an oxygen carrier, comprising calcining a mixture of ferric titanate particles and an alkaline component to produce an activated ferric titanate oxygen carrier containing alkali metal titanate and iron oxide, characterized in that... The iron titanate particles are brought into contact with alkaline components in a high-temperature reaction apparatus.

6. The method for manufacturing an oxygen carrier as described in claim 5, wherein, The high-temperature reaction device is a fluidized bed or circulating fluidized bed that contains ferric titanate particles as the flowing medium.

7. The method for manufacturing an oxygen carrier as described in claim 5 or 6, wherein, The temperature of the high-temperature reaction device is 800℃~1000℃.

8. The method for manufacturing an oxygen carrier as described in claim 5 or 6, wherein, The alkaline component is supplied separately from the fuel used for combustion.

9. The method for manufacturing an oxygen carrier as described in claim 5 or 6, wherein, The alkaline component is supplied as fuel for combustion.

10. The method for manufacturing an oxygen carrier as described in claim 9, wherein, The fuel is selected from lignite and biomass.

11. A method for producing hydrogen, characterized in that, It has the following processes: The air combustion process involves burning fuel in the presence of iron titanate particles; The fuel reaction activation process involves contacting ferric titanate particles with alkaline components to generate activated ferric titanate containing alkali metal titanates and iron oxide; and The hydrogen generation process generates hydrogen through the reaction of iron oxide generated in the fuel reaction activation process with water vapor.

12. The hydrogen production method as described in claim 11, wherein, The fuel reaction activation process is carried out at 800℃~980℃.

13. The hydrogen production method as described in claim 11 or 12, wherein, The alkaline component is supplied separately from the fuel used for combustion.

14. The hydrogen production method as described in claim 11 or 12, wherein, The alkaline component is supplied as fuel for combustion.

15. The hydrogen production method as described in claim 14, wherein, The fuel is selected from lignite and biomass.

16. A hydrogen production apparatus, characterized in that, It possesses: An air combustion tower burns fuel in the presence of iron titanate particles; The fuel reaction activation tower contacts ferric titanate particles with alkaline components to generate activated ferric titanate containing alkali metal titanates and iron oxide; and, The hydrogen generation tower generates hydrogen through the reaction of iron oxide generated in the fuel reaction activation tower with water vapor.

17. The hydrogen production apparatus of claim 16, wherein, The temperature of the fuel reaction activation tower is 800℃~980℃.

18. The hydrogen production apparatus as claimed in claim 16 or 17, wherein, The alkaline component is an alkaline compound supplied separately from the fuel used for combustion.

19. The hydrogen production apparatus as claimed in claim 16 or 17, wherein, The alkaline component is contained in the fuel used for combustion.

20. The hydrogen production apparatus of claim 19, wherein, The fuel is selected from lignite and biomass.

21. A method for producing hydrogen, comprising reacting an oxygen carrier with water vapor to produce hydrogen, wherein, The oxygen carrier is an oxygen carrier manufactured by the method described in claim 1 or 5.

22. An oxygen carrier, manufactured by the method of claim 3, comprising potassium titanate as an alkali metal titanate.

23. The oxygen carrier as claimed in claim 22, wherein, The potassium to titanium molar ratio K / Ti in the potassium titanate is greater than 0.

008.

24. A chemical chaining combustion method using the oxygen carrier as described in claim 23.

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