Preparation method and application of wide-temperature oxygen carrier for chemical looping hydrogen production

Abstract

The application discloses a preparation method and application of a wide-temperature oxygen carrier for chemical chain hydrogen production, and belongs to the technical field of energy chemical industry. The method comprises the following steps: firstly, a proper amount of iron nitrate, copper nitrate, zirconium nitrate and cerium nitrate are added into deionized water and uniformly mixed; under stirring, a proper amount of a precipitant is added dropwise, the pH value of the mixed nitrate solution is adjusted to 9-12; then, under the condition of 60-90 DEG C, the solution is reacted for 0.5-3 hours first, and then is statically placed for 0.5-3 hours; the slurry after the static placement is filtered, washed and dried; the dried powder is calcined, ground and sieved to obtain wide-temperature oxygen carrier particles. The method has the advantages of simple process, convenient operation, low cost and low energy consumption; the prepared oxygen carrier has good activity in a wide temperature range, can produce hydrogen, the produced hydrogen has high purity, and has good stability in cyclic use.

Description

Technical Field

[0001] This invention belongs to the field of energy and chemical technology, specifically relating to a method for preparing a wide-temperature oxygen carrier for chemical chain hydrogen production and its application. Background Technology

[0002] Hydrogen (H2), as a zero-CO2 emission energy carrier, has seen rapid demand growth in recent years and is considered an ideal choice for automotive fuel and energy production in the coming decades. Blast furnace gas is a combustible gas produced as a byproduct of ironmaking in steel mills; 2200 m³ of gas is produced for every ton of iron produced. 3 Blast furnace gas contains 20%–30% CO, thus possessing significant potential for hydrogen production. However, blast furnace gas also contains large amounts of inert gases (N2, CO2), leading to challenges in hydrogen production from it, such as high separation costs and low hydrogen purity.

[0003] Chemical looping hydrogen production, as a novel hydrogen production technology, has attracted widespread attention due to its advantages such as low energy consumption, high efficiency, and environmental friendliness. Because chemical looping hydrogen production produces high-purity hydrogen, using blast furnace gas as fuel not only converts low-calorific-value waste gas into valuable hydrogen energy but also reduces CO2 emissions, lowers hydrogen production costs, and reduces energy consumption.

[0004] In chemical looping hydrogen production, oxygen carriers, acting as catalysts and oxygen sources, play a crucial role in the generation and regeneration of H2. Currently, inexpensive and widely available iron oxides are considered ideal oxygen carrier materials. However, traditional iron-based oxygen carriers have high reduction temperatures (typically above 800℃), which not only easily leads to sintering deactivation but also results in high energy consumption and costs for hydrogen production. Existing technology CN111232920A discloses a method for chemical looping hydrogen production from coke oven gas, and the prepared oxygen carrier enables the clean utilization of coke oven gas, but its reaction temperature exceeds 750℃. Existing technology CN113731419A discloses the application and preparation of an oxygen carrier in chemical looping hydrogen production; Fe2O3 combined with attapulgite can improve the cycle stability of the oxygen carrier, but this oxygen carrier requires a high temperature of 750℃ to 950℃ to perform chemical looping hydrogen production. Existing technology CN106185807A discloses a pilot-scale single-tower fixed-bed chemical looping hydrogen production device and method, which requires operation at temperatures as high as 700℃. Current research is mostly limited to the preparation of oxygen carriers for high-temperature chemical looping hydrogen production, and the development, preparation, and application of oxygen carriers under medium- and low-temperature conditions still have certain limitations. Therefore, there is an urgent need to develop a method for preparing oxygen carriers with a wide temperature range. By controlling and improving the composition of the oxygen carrier, its redox activity and cycle stability can be enhanced, the operating temperature range broadened, and energy consumption and costs reduced, thereby promoting the further development and application of chemical looping hydrogen production technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a wide-temperature oxygen carrier for chemical chain hydrogen production. The process is simple, easy to operate, and has low cost and energy consumption, which can effectively improve the above-mentioned problems.

[0006] The embodiments of the present invention are implemented as follows:

[0007] The present invention provides a method for preparing a wide-temperature oxygen carrier for chemical chain hydrogen production.

[0008] Includes the following steps:

[0009] S1: Take appropriate amounts of ferric nitrate, copper nitrate, zirconium nitrate and cerium nitrate respectively, add them to deionized water and mix well to obtain a nitrate mixed solution;

[0010] S2: Add an appropriate amount of precipitant dropwise under stirring to adjust the pH of the nitrate mixed solution to 9-12. Then react at 60-90℃ for 0.5-3 hours and let it stand for 0.5-3 hours.

[0011] S3: After the slurry has been left to stand, it is filtered, washed, and dried. The dried powder is then calcined, ground, and sieved to obtain wide-temperature oxygen carrier particles.

[0012] Furthermore, in step S1, the mass fractions of each raw material component are 50-85% ferric nitrate, 10-40% copper nitrate, 2.5-10% zirconium nitrate, and 2.5-10% cerium nitrate.

[0013] Furthermore, in step S1, after each raw material is added to deionized water, it needs to be stirred at 70°C for 30 minutes.

[0014] Furthermore, in step S2, the precipitant is ammonia and / or sodium hydroxide solution.

[0015] Furthermore, in step S3, after filtering and washing the slurry, it is dried at 90°C for 24 hours to obtain hydroxide precursor powder.

[0016] Furthermore, in step S3, the calcination conditions are as follows: the hydroxide precursor powder is first kept at 400℃ for 2 hours, then heated to 800-1000℃ and kept at 800-1000℃ for 1-6 hours, and then ground and sieved to obtain oxygen carrier particles.

[0017] The present invention also provides an application of a wide-temperature oxygen carrier in the chemical looping hydrogen production from blast furnace gas. The wide-temperature oxygen carrier is an oxygen carrier particle prepared by the above preparation method. The hydrogen production process is as follows: in the reduction stage, the wide-temperature oxygen carrier reacts with blast furnace gas to obtain a reduced oxygen carrier; in the oxidation stage, the reduced oxygen carrier reacts with water vapor to generate H2, while restoring lattice oxygen, thereby realizing the recycling and regeneration of the oxygen carrier.

[0018] Furthermore, the reaction temperature for the reduction stage is 550-850℃, and the reaction temperature for the oxidation stage is 550-850℃.

[0019] Furthermore, in the reduction stage, the CO:CO2 ratio in the blast furnace gas is (1-3):1.

[0020] The beneficial effects of this invention are as follows:

[0021] The method for preparing a wide-temperature oxygen carrier for chemical chain hydrogen production provided by the present invention is simple, easy to operate, and has low cost and energy consumption. The prepared oxygen carrier has good activity over a wide temperature range and can produce hydrogen. Moreover, the produced hydrogen has high purity, good stability for recycling, and does not exhibit obvious sintering or agglomeration. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram showing the change in hydrogen production over time at different temperatures of the oxygen carrier prepared in Example 1 of the present invention.

[0024] Figure 2 This is a schematic diagram showing the change in hydrogen production as a function of the number of cycles in the chemical looping hydrogen production cycle experiment using the oxygen carriers prepared in Examples 1-3 of the present invention.

[0025] Figure 3 This is a schematic diagram showing the change in hydrogen purity with the number of cycles in a chemical looping hydrogen production cycle experiment using the oxygen carrier prepared in Example 1 of the present invention.

[0026] Figure 4 This is a comparison diagram of the elemental distribution of the oxygen carrier prepared in Example 1 of the present invention before and after the chemical loop hydrogen production cycle;

[0027] Figure 5 The images show the XRD patterns of the oxygen carriers prepared in Examples 1-3 of this invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0031] Example 1

[0032] Embodiment 1 of the present invention provides a method for preparing a wide-temperature oxygen carrier for chemical chain hydrogen production, comprising the following steps:

[0033] S1: Take appropriate amounts of ferric nitrate, copper nitrate, zirconium nitrate and cerium nitrate respectively, add them to deionized water and mix well to obtain a nitrate mixed solution.

[0034] In this embodiment, 20.2g of ferric nitrate powder, 6.04g of copper nitrate powder, 2.415g of zirconium nitrate powder and 0.815g of cerium nitrate powder were weighed and mixed evenly. Then, the mixture was added to deionized water and stirred at 70°C for 30 minutes to ensure complete dissolution and obtain a uniform nitrate solution.

[0035] S2: Add a precipitant dropwise to the nitrate solution under stirring conditions. When the pH value of the nitrate mixture reaches a certain value, continue stirring for a certain period of time, and then let it stand.

[0036] The precipitant can be ammonia, sodium hydroxide, or a mixture of ammonia and sodium hydroxide. In this embodiment, sodium hydroxide is used as the precipitant.

[0037] The pH value of the solution can be adjusted to 9-12. In this embodiment, the pH value is adjusted to about 11. Then, the solution is stirred at 70°C for about 3 hours and then allowed to stand for 3 hours to ensure complete precipitation, thus obtaining the hydroxide precursor slurry.

[0038] S3: After the slurry has been left to stand, it is filtered, washed, and dried. The dried powder is then calcined, ground, and sieved to obtain wide-temperature oxygen carrier particles.

[0039] In this step, the hydroxide precursor slurry is centrifuged and filtered, then washed to obtain the hydroxide precursor. In this embodiment, deionized water is used to wash three times to remove sodium salt from the slurry. Then, it is dried at 90°C for 24 hours to obtain hydroxide precursor powder. The hydroxide precursor powder is then calcined at 400°C for 2 hours, then heated to 1000°C and held for 2 hours. After being cooled to room temperature in the furnace, it is ground and sieved to obtain oxygen carrier particles, labeled as CuFe2O4-7.5%Zr-2.5%Ce. It can be sieved using a 20-100 mesh sieve.

[0040] The oxygen carrier performance test results for this embodiment are as follows:

[0041] Four 0.5g portions of CuFe2O4-7.5%Zr-2.5%Ce oxygen carrier particles were weighed and placed in fixed-bed reactors for testing. After the samples were placed in the fixed-bed reactors, nitrogen gas was introduced into the reactors. Under the nitrogen atmosphere, the fixed-bed reactors of the four groups of samples were heated to 550℃, 650℃, 750℃ and 850℃ respectively. Then, blast furnace gas was introduced into the fixed-bed reactors at a flow rate of 500mL / min for 30min. This was to allow the blast furnace gas to consume the lattice oxygen in the oxygen carrier, thereby obtaining a reduced oxygen carrier.

[0042] After stopping the blast furnace gas supply, purge with nitrogen for 10 minutes, and then introduce water and nitrogen into the evaporator. The water pumping rate is 0.05 mL / min, and the nitrogen delivery rate is 500 mL / min. In the evaporator, the water turns into water vapor and mixes with nitrogen to obtain a mixed gas. This mixed gas is then introduced into a fixed-bed reactor for oxidation reaction. This is to allow the reduced oxygen carrier to recover lattice oxygen and generate H2. The flow rate of the mixed gas is set to 500 mL / min, and the delivery time is 30 minutes to ensure a complete reaction. After stopping the supply of the water vapor and nitrogen mixed gas, purge with nitrogen for 10 minutes.

[0043] In this embodiment, the composition of the blast furnace gas is CO:CO2 = 2:1. During the oxidation reaction, the temperature of the fixed-bed reactor is the same as that during the reduction reaction.

[0044] Online detection was performed at the outlet of the fixed-bed reactor using a gas analyzer to obtain the hydrogen production under four sets of reaction temperature conditions, as follows: Figure 1 As shown in the figure, the hydrogen yield exceeded 10 mmol / g under all four reaction temperature conditions, indicating that the oxygen carrier exhibits good activity over a wide temperature range and can perform chemical chain hydrogen production. The highest hydrogen yield, reaching 11.34 mmol / g, was observed at a reaction temperature of 550℃.

[0045] For the experimental group with a fixed-bed reactor temperature of 550℃, the above steps were repeated, and the hydrogen production experiment was carried out 10 times in a cycle. The results are as follows:

[0046] Hydrogen production such as Figure 2 As shown in the curve (indicated by the black dot), all reached 11 mmol / g, indicating that the oxygen carrier can be deeply reduced by blast furnace gas and can recover lattice oxygen in water vapor. No decrease in hydrogen production capacity was observed after multiple uses of the oxygen carrier, indicating that the prepared oxygen carrier has good stability.

[0047] The purity of hydrogen gas is as follows Figure 3 As shown, the purity levels all reached over 99%, indicating that this method can achieve the preparation of high-purity hydrogen.

[0048] Changes in microstructure before and after the oxygen carrier reaction, such as Figure 4 As shown in the figure, after 10 cycles of chemical chain hydrogen production, the microstructure of the oxygen carrier did not change significantly, and there was no uneven distribution of elements, indicating that the oxygen carrier has good cycle stability.

[0049] Example 2

[0050] Embodiment 2 of the present invention provides a method for preparing a wide-temperature oxygen carrier for chemical chain hydrogen production, comprising the following steps:

[0051] S1: Take appropriate amounts of ferric nitrate, copper nitrate, zirconium nitrate and cerium nitrate respectively, add them to deionized water and mix well to obtain a nitrate mixed solution.

[0052] In this embodiment, 22.22g of ferric nitrate powder, 4.83g of copper nitrate powder, 1.61g of zirconium nitrate powder and 1.63g of cerium nitrate powder were weighed and mixed evenly. Then, the mixture was added to deionized water and stirred at 70°C for 30 minutes to ensure complete dissolution and obtain a uniform nitrate solution.

[0053] S2: Add a precipitant dropwise to the nitrate solution under stirring conditions. When the pH value of the nitrate mixture reaches a certain value, continue stirring for a certain period of time, and then let it stand.

[0054] The precipitant can be ammonia, sodium hydroxide, or a mixture of ammonia and sodium hydroxide. In this embodiment, sodium hydroxide is used as the precipitant.

[0055] The pH value of the solution can be adjusted to 9-12. In this embodiment, the pH value is adjusted to about 11. Then, the solution is stirred at 70°C for about 3 hours and then allowed to stand for 3 hours to obtain the hydroxide precursor slurry.

[0056] S3: After the slurry has been left to stand, it is filtered, washed, and dried. The dried powder is then calcined, ground, and sieved to obtain wide-temperature oxygen carrier particles.

[0057] In this step, the slurry is centrifuged and filtered, then washed to obtain a hydroxide precursor. This precursor is then dried at 90°C for 24 hours to obtain hydroxide precursor powder. The powder is then calcined at 400°C for 2 hours, then heated to 1000°C and held for 2 hours. After cooling to room temperature in the furnace, it is ground and sieved to obtain oxygen carrier particles, labeled as Cu. 0.8 Fe 2.2 O 4-δ -5% Zr-5% Ce can be screened using a 20-100 mesh sieve.

[0058] The oxygen carrier performance test results for this embodiment are as follows:

[0059] Weigh out 0.5g of Cu 0.8 Fe 2.2 O 4-δ -5% Zr-5% Ce oxygen carrier particles were placed in a fixed-bed reactor, and then nitrogen gas was introduced into the reactor. Under the nitrogen atmosphere, the fixed-bed reactor was heated to 550℃. Then, blast furnace gas was introduced into the fixed-bed reactor at a flow rate of 500 mL / min for 30 min. This was to allow the blast furnace gas to consume the lattice oxygen in the oxygen carrier, thereby obtaining a reduced oxygen carrier.

[0060] After stopping the blast furnace gas supply, purge with nitrogen for 10 minutes, and then introduce water and nitrogen into the evaporator. The water pumping flow rate is 0.05 mL / min, and the nitrogen delivery flow rate is 500 mL / min. In the evaporator, the water turns into water vapor and mixes with nitrogen to obtain a mixed gas. This mixed gas is then introduced into a fixed-bed reactor for oxidation reaction. This is to allow the reduced oxygen carrier to recover lattice oxygen and generate H2. The flow rate of the mixed gas is set to 500 mL / min, and the delivery time is 30 minutes to ensure a complete reaction. After stopping the supply of the water vapor and nitrogen mixed gas, purge with nitrogen for 10 minutes.

[0061] In this embodiment, the blast furnace gas has a CO:CO2 ratio of 3:1. During the oxidation reaction, the temperature of the fixed-bed reactor is maintained at 550°C.

[0062] Repeat the above steps to conduct 10 hydrogen production experiments. The hydrogen production rate is as follows: Figure 2 As shown in the curves (circular black dots), all reached 10 mmol / g or higher, indicating that the prepared oxygen carrier has a stable hydrogen production capacity.

[0063] Example 3

[0064] Embodiment 3 of the present invention provides a method for preparing a wide-temperature oxygen carrier for chemical chain hydrogen production, comprising the following steps:

[0065] S1: Take appropriate amounts of ferric nitrate, copper nitrate, zirconium nitrate and cerium nitrate respectively, add them to deionized water and mix well to obtain a nitrate mixed solution.

[0066] In this embodiment, 26.26g of ferric nitrate powder, 2.42g of copper nitrate powder, 1.61g of zirconium nitrate powder and 1.63g of cerium nitrate powder were weighed and mixed evenly. Then, the mixture was added to deionized water and stirred at 70°C for 30 minutes to ensure complete dissolution and obtain a uniform nitrate solution.

[0067] S2: Add a precipitant dropwise to the nitrate solution under stirring conditions. When the pH value of the nitrate mixture reaches a certain value, continue stirring for a certain period of time, and then let it stand.

[0068] The precipitant can be ammonia, sodium hydroxide, or a mixture of ammonia and sodium hydroxide. In this embodiment, sodium hydroxide is used as the precipitant.

[0069] The pH value of the solution can be adjusted to 9-12. In this embodiment, the pH value is adjusted to about 11. Then, the solution is stirred at 70°C for about 3 hours and then allowed to stand for 3 hours to obtain the hydroxide precursor slurry.

[0070] S3: After the slurry has been left to stand, it is filtered, washed, and dried. The dried powder is then calcined, ground, and sieved to obtain wide-temperature oxygen carrier particles.

[0071] In this step, the slurry is centrifuged and filtered, then washed to obtain a hydroxide precursor. This precursor is then dried at 90°C for 24 hours to obtain hydroxide precursor powder. The powder is then calcined at 400°C for 2 hours, then heated to 1000°C and held for 2 hours. After cooling to room temperature in the furnace, it is ground and sieved to obtain oxygen carrier particles, labeled as Cu. 0.4 Fe 2.6 O 4-δ -5% Zr-5% Ce can be screened using a 20-100 mesh sieve.

[0072] The oxygen carrier performance test results for this embodiment are as follows:

[0073] Weigh out 0.5g of Cu 0.4 Fe 2.6 O 4-δ -5% Zr-5% Ce oxygen carrier particles were placed in a fixed-bed reactor, and then nitrogen gas was introduced into the fixed-bed reactor. Under the nitrogen atmosphere, the fixed-bed reactor was heated to 550℃. Then, blast furnace gas was introduced into the fixed-bed reactor at a flow rate of 500 mL / min for 30 min. This was to allow the blast furnace gas to consume the lattice oxygen in the oxygen carrier, thereby obtaining a reduced oxygen carrier.

[0074] After stopping the blast furnace gas supply, purge with nitrogen for 10 minutes, and then introduce water and nitrogen into the evaporator. The water pumping flow rate is 0.05 mL / min, and the nitrogen delivery flow rate is 500 mL / min. In the evaporator, the water turns into water vapor and mixes with nitrogen to obtain a mixed gas. This mixed gas is then introduced into a fixed-bed reactor for oxidation reaction. This is to allow the reduced oxygen carrier to recover lattice oxygen and generate H2. The flow rate of the mixed gas is set to 500 mL / min, and the delivery time is 30 minutes to ensure a complete reaction. After stopping the supply of the water vapor and nitrogen mixed gas, purge with nitrogen for 10 minutes.

[0075] In this embodiment, the composition of the blast furnace gas is CO:CO2 = 3:1. During the oxidation reaction, the temperature of the fixed-bed reactor is maintained at 550°C.

[0076] Repeat the above steps to conduct 10 hydrogen production experiments. The hydrogen production yield is as follows: Figure 2 As shown in the figure (curves indicated by the quadrilateral black dots), all reached above 8 mmol / g, indicating that there are certain differences in the hydrogen production of oxygen carriers made from different ratios of raw materials.

[0077] XRD analysis was performed on the oxygen carriers prepared in Examples 1, 2, and 3, and the results are as follows: Figure 5 As shown in the figure, there are some differences in the oxygen carriers prepared with different raw material ratios. The main components are CuFe2O4 and Zr. x Ce 1-x When Cu / Fe < 0.5, some Fe2O3 is still present in the oxygen carrier. However, this has little impact on the relative activity, cycle stability, and hydrogen production purity. The composition of the oxygen carrier is the main factor affecting stability and activity.

[0078] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. The application of a wide-temperature oxygen carrier in the chemical looping of hydrogen production from blast furnace gas, characterized in that: The hydrogen production process is as follows: in the reduction stage, a wide-temperature oxygen carrier reacts with blast furnace gas to obtain a reduced oxygen carrier; in the oxidation stage, the reduced oxygen carrier reacts with water vapor to generate H2, while restoring lattice oxygen and realizing the recycling and regeneration of the oxygen carrier. The reaction temperature of the reduction stage is 550-850℃, and the reaction temperature of the oxidation stage is 550-850℃. The method for preparing the wide-temperature oxygen carrier for chemical loop hydrogen production includes the following steps: S1: Take 50-85% ferric nitrate, 10-40% copper nitrate, 2.5-10% zirconium nitrate and 2.5-10% cerium nitrate by mass and add them to deionized water and mix well to obtain a nitrate mixed solution; S2: Add precipitant dropwise under stirring to adjust the pH of the nitrate mixture to 9-12, then react at 60-90℃ for 0.5-3 hours, and then let it stand for 0.5-3 hours. S3: After the slurry has been allowed to stand, it is filtered, washed, and dried. The dried powder is then calcined, ground, and sieved to obtain wide-temperature oxygen carrier particles. Specifically, after filtering and washing the slurry, it is dried at 90°C for 24 hours to obtain hydroxide precursor powder. The calcination conditions are as follows: the hydroxide precursor powder is first kept at 400°C for 2 hours, and then heated to 800-1000°C and kept at 800-1000°C for 1-6 hours. After grinding and sieving, oxygen carrier particles are obtained.

2. The application of the wide-temperature oxygen carrier according to claim 1 in the chemical looping of hydrogen production from blast furnace gas, characterized in that: In step S1, after each raw material is added to deionized water, it needs to be stirred at 70°C for 30 minutes.

3. The application of the wide-temperature oxygen carrier according to claim 1 in the chemical looping of hydrogen production from blast furnace gas, characterized in that: In step S2, the precipitant is ammonia and / or sodium hydroxide solution.

4. The application of the wide-temperature oxygen carrier according to claim 3 in the chemical looping hydrogen production from blast furnace gas, characterized in that: During the reduction stage, the CO:CO2 ratio in the blast furnace gas is (1-3):1.

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