A method for hydrogen production by methane chemical looping

Abstract

The application provides a method for preparing hydrogen by methane chemical looping. The method comprises: contacting methane with a first oxygen carrier to perform a first reaction to prepare syngas and a reduced first oxygen carrier; wherein the first oxygen carrier is selected from an oxygen carrier with a chemical formula of Fe 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 Al2O4; the syngas obtained by the first reaction is contacted with a second oxygen carrier to perform a second reaction to prepare CO2 and a reduced second oxygen carrier; wherein the second oxygen carrier is selected from an oxygen carrier with a chemical formula of LaAl 1 / 4 Co 1 / 4 Mn 1 / 4 Fe 1 / 4O3; the reduced second oxygen carrier is contacted with water vapor to perform a third reaction to prepare hydrogen and a partially oxidized second oxygen carrier; the partially oxidized second oxygen carrier is subjected to a complete oxidation reaction to obtain a second oxygen carrier, and the second oxygen carrier is recycled for the second reaction.

Description

Technical Field

[0001] This invention belongs to the field of chemical chain hydrogen production technology, specifically relating to a method for producing hydrogen from methane through a chemical chain. Background Technology

[0002] Hydrogen is a highly efficient and clean energy source. Currently, methane steam reforming dominates the hydrogen production process market. Methane steam reforming achieves syngas production and hydrogen enrichment through high-temperature steam reforming and medium-low temperature water-gas shift reaction, respectively. Finally, H2 and CO2 are separated using physical / chemical absorption methods or pressure swing adsorption. Traditional methane steam reforming hydrogen production processes have high energy consumption, low equilibrium conversion rates, and require additional CO2 separation processes, resulting in high equipment investment and operating costs.

[0003] To address the aforementioned issues, researchers applied chemical looping technology to the methane steam reforming hydrogen production process, enabling near-zero energy in-situ separation of products while producing hydrogen. The chemical looping process breaks down the overall reaction into two or more sub-reactions occurring in different spaces or time intervals, with an oxygen carrier circulating through each reaction for mass and heat transfer. Chemical looping hydrogen production can be decomposed into two reactions: chemical looping combustion and chemical looping reforming. The chemical looping combustion reaction is a fuel oxidation reaction, using a highly oxidizing oxygen carrier to completely convert carbon in the fuel into CO2. The reduced oxygen carrier is recycled to the chemical looping reforming unit to react with water to generate hydrogen and undergo partial oxidation and regeneration. Subsequently, the oxygen carrier is completely regenerated by air oxidation and recycled. Chemical looping hydrogen production allows CO2 and H2 to be generated separately in different units, eliminating the need for complex separation equipment, improving H2 purity, and increasing CO2 capture efficiency.

[0004] Currently, chemical looping hydrogen production is still in the laboratory research stage and cannot yet be industrialized. CN102198934A discloses a chemical looping hydrogen production method and apparatus, using perovskite oxide as an oxygen carrier. The reaction cycle is carried out sequentially through a fuel reactor, a steam reactor, and an air reactor. By providing and restoring lattice oxygen, the chemical looping combustion of fuel and the steam hydrogen production reaction are achieved, respectively, generating pure H2 while automatically separating CO2. CN107539949A uses a four-bed countercurrent moving bed reactor. In the methane combustion stage, a dual-bed countercurrent configuration is used to achieve complete methane combustion. Subsequently, the process of water hydrogen production and oxygen carrier oxidation is achieved through a water hydrogen production fluidized bed and an air riser reactor. Existing chemical looping hydrogen production technologies all use the same oxygen carrier to sequentially achieve fuel combustion and water hydrogen production. They generally suffer from problems such as the inability to simultaneously achieve high CO2 capture rates and high hydrogen production rates, the tendency for oxygen-carrying volume carbon, and low hydrogen purity.

[0005] Therefore, new chemical chaining methods for producing hydrogen from methane are still needed to achieve high methane conversion, high CO2 capture rate, high hydrogen yield, and high hydrogen purity. Summary of the Invention

[0006] The purpose of this invention is to provide a chemical chain hydrogen production technology solution for methane that can achieve high methane conversion rate, high CO2 capture rate, high hydrogen yield and high hydrogen purity.

[0007] To address the above problems, this invention provides a method for producing hydrogen from methane through a chemical chain, wherein the method includes:

[0008] Methane is reacted with a first oxygen carrier to undergo a first reaction, producing syngas and a reduced first oxygen carrier; wherein the first oxygen carrier is selected with the chemical formula Fe. 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 An oxygen carrier for Al2O4;

[0009] The syngas obtained from the first reaction is contacted with the second oxygen carrier to carry out a second reaction, producing CO2 and the reduced second oxygen carrier; wherein the second oxygen carrier is selected with the chemical formula LaAl. 1 / 4 Co 1 / 4 Mn 1 / 4 Fe 1 / 4 O3 oxygen carrier;

[0010] The reduced second oxygen carrier is contacted with water vapor to carry out a third reaction, producing hydrogen and a partially oxidized second oxygen carrier;

[0011] The partially oxidized second oxygen carrier is subjected to a complete oxidation reaction to obtain a second oxygen carrier, which is then recycled for use in the second reaction.

[0012] The methane chemical chain hydrogen production method provided by this invention addresses the different requirements of the oxygen carrier's equilibrium oxygen partial pressure and surface active site structure for the processes of methane to syngas production and syngas to hydrogen production while simultaneously capturing CO2. It employs oxygen carriers with different equilibrium oxygen partial pressures and surface active site structures to achieve complete methane conversion to syngas and syngas to hydrogen production while simultaneously capturing CO2. This method utilizes Fe, which has low equilibrium oxygen partial pressure, high methane activation capacity, and weak oxidizing capacity. 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 During the methane conversion to syngas process using Al2O4 oxygen carrier, a medium equilibrium oxygen partial pressure (pO2 = 10) is employed. -19 -10 -16 LaAl, after reduction, can be partially or completely oxidized by water vapor. 1 / 4Co 1 / 4 Mn 1 / 4 Fe 1 / 4 With the O3 oxygen carrier completely oxidizing and capturing CO2 while being reduced, and then being oxidized and regenerated by water vapor to produce hydrogen, the chemical chain hydrogen production process of methane achieves high methane conversion rate, high CO2 capture rate, high hydrogen yield and high hydrogen purity.

[0013] According to a preferred embodiment of the methane chemical chain hydrogen production method, the process of reacting methane with a first oxygen carrier to produce syngas and a reduced first oxygen carrier includes:

[0014] Methane and the first oxygen carrier come into contact in a fluidized bed to carry out the first reaction;

[0015] The products after the first reaction are subjected to gas-solid separation. The gas phase product obtained is the synthesis gas, and the solid phase product is the reduced first oxygen carrier.

[0016] Furthermore, the gas-solid separation of the products after the first reaction is carried out using a cyclone separator in conjunction with a riser (wherein, the solid phase outlet of the cyclone separator is connected to the riser).

[0017] Furthermore, the first reaction in which methane contacts the first oxygen carrier in a fluidized bed includes:

[0018] After reacting with the first oxygen carrier in the main reaction zone, methane enters the riser section to continue the reaction; the main reaction zone adopts a bubbling fluidized bed or a turbulent fluidized bed, and the riser section adopts a fast fluidized bed.

[0019] According to a preferred embodiment of the methane chemical chain hydrogen production method, the temperature of the first reaction is 900-1100℃; the pressure of the first reaction is 0.1-0.3MPa.

[0020] According to a preferred embodiment of the methane chemical chain hydrogen production method, the ratio of methane to the first oxygen carrier is 1-3 mL: 1 g.

[0021] According to a preferred embodiment of the methane chemical chain hydrogen production method, the method further includes:

[0022] The reduced first oxygen carrier was subjected to a complete oxidation reaction to prepare the first oxygen carrier.

[0023] The prepared first oxygen carrier was used in the first reaction;

[0024] Furthermore, the method also includes: the reduced first oxygen carrier is treated using an overflow tank before undergoing a complete oxidation reaction;

[0025] Further, the reduction of the first oxygen carrier is subjected to an oxidation reaction to prepare the first oxygen carrier, which includes: the reduction of the first oxygen carrier and the first oxidizing gas are contacted in a fluidized bed to carry out an oxidation reaction; wherein, the first oxidizing gas stream is preferably air; the product after the oxidation reaction of the first oxygen carrier is subjected to gas-solid separation, and the obtained solid product is the first oxygen carrier; wherein, the gas-solid separation is preferably carried out using a cyclone separator in conjunction with a riser (wherein, the solid phase outlet of the cyclone separator is connected to the riser); further still, the reduction of the first oxygen carrier and the first oxidizing gas are contacted in a fluidized bed to carry out an oxidation reaction, which includes: the reduction of the first oxygen carrier and the first oxidizing gas are contacted in the main reaction zone to carry out the reaction and then enter the riser section to continue the reaction; wherein, the main reaction zone adopts the form of a bubbling fluidized bed or a turbulent fluidized bed, and the riser section adopts the form of a fast fluidized bed;

[0026] Furthermore, the oxidation reaction of the reduced first oxygen carrier is carried out at a temperature of 900-1100℃; the pressure of the reduced first oxygen carrier is 0.1-0.3MPa.

[0027] Furthermore, the method also includes: treating the first oxygen carrier in an overflow tank before recycling it in the first reaction.

[0028] According to a preferred embodiment of the methane chemical chain hydrogen production method, the temperature of the second reaction is 800-900°C; the pressure of the second reaction is 0.1-0.3 MPa.

[0029] According to a preferred embodiment of the methane chemical chain hydrogen production method, the ratio of the syngas obtained from the first reaction to the second oxygen carrier is 1-3 mL: 1 g.

[0030] According to a preferred embodiment of the methane chemical chain hydrogen production method, the syngas obtained from the first reaction is contacted with a second oxygen carrier to carry out a second reaction, producing CO2 and a reduced second oxygen carrier, comprising:

[0031] The syngas obtained from the first reaction comes into contact with the second oxygen carrier in a fluidized bed through countercurrent flow to carry out the second reaction;

[0032] The solid product obtained from the second reaction is the reduced second oxygen carrier.

[0033] The gaseous product obtained from the second reaction is treated by an overflow tank and then subjected to gas-solid separation. The resulting gaseous product is CO2.

[0034] Furthermore, during the gas-solid separation process after the gaseous product obtained from the second reaction is treated by the overflow tank, the solid separation is carried out using a cyclone separator in conjunction with a riser (wherein, the solid phase outlet of the cyclone separator is connected to the riser).

[0035] Furthermore, the method further includes: treating the gaseous product obtained from the second reaction through an overflow tank and then performing gas-solid separation to obtain a solid product, which is then subjected to a complete oxidation reaction with the partially oxidized second oxygen carrier to obtain a second oxygen carrier; wherein, the gas-solid separation is preferably performed using a cyclone separator in conjunction with a riser (wherein, the solid outlet of the cyclone separator is connected to the riser).

[0036] According to a preferred embodiment of the methane chemical chain hydrogen production method, the temperature of the third reaction is 850-950°C; the pressure of the third reaction is 0.1-0.3 MPa.

[0037] According to a preferred embodiment of the methane chemical chain hydrogen production method, the ratio of water vapor to the reduced second oxygen carrier is 5-10 mL: 1 g.

[0038] According to a preferred embodiment of the methane chemical chain hydrogen production method, the reduced second oxygen carrier is contacted with water vapor to undergo a third reaction to prepare hydrogen and a partially oxidized second oxygen carrier, comprising:

[0039] The reduced second oxygen carrier comes into contact with water vapor in a fluidized bed to carry out a third reaction;

[0040] The product after the third reaction is subjected to gas-solid separation. The gas phase product is hydrogen, and the solid phase product is the partially oxidized second oxygen carrier.

[0041] Furthermore, the reduced second oxygen carrier contacts water vapor in the fluidized bed to carry out a third reaction, including:

[0042] After reduction, the second oxygen carrier reacts with water vapor in the main reaction zone and then enters the riser section to continue the reaction; the main reaction zone adopts a bubbling fluidized bed or a turbulent fluidized bed, and the riser section adopts a rapid fluidized bed.

[0043] Furthermore, the gas-solid separation of the products after the third reaction is carried out using a cyclone separator in conjunction with a riser (wherein, the solid phase outlet of the cyclone separator is connected to the riser).

[0044] According to a preferred embodiment of the methane chemical chain hydrogen production method, the partially oxidized second oxygen carrier is treated using an overflow tank before undergoing a complete oxidation reaction to obtain the second oxygen carrier.

[0045] According to a preferred embodiment of the methane chemical chain hydrogen production method, during the complete oxidation reaction of the partially oxidized second oxygen carrier, the reaction temperature is 900-1100℃ and the reaction pressure is 0.1-0.3MPa.

[0046] According to a preferred embodiment of the methane chemical chain hydrogen production method, the process of completely oxidizing a partially oxidized second oxygen carrier to obtain a second oxygen carrier, and recycling the second oxygen carrier in a second reaction, includes:

[0047] The partially oxidized second oxygen carrier and the second oxidizing gas come into contact in a fluidized bed to carry out a complete oxidation reaction; wherein, the second oxidizing gas stream is preferably air;

[0048] The product after the oxidation reaction is subjected to gas-solid separation, and the resulting solid product is the second oxygen carrier.

[0049] Furthermore, the partial oxidation of the second oxygen carrier and the second oxidizing gas in the fluidized bed to carry out a complete oxidation reaction includes:

[0050] The partially oxidized second oxygen carrier reacts with the second oxidizing gas in the main reaction zone and then enters the riser section to continue the reaction; the main reaction zone adopts the form of a bubbling fluidized bed or a turbulent fluidized bed, and the riser section adopts the form of a fast fluidized bed;

[0051] Furthermore, in the gas-solid separation process of the products after the oxidation reaction, the gas-solid separation is preferably carried out by a cyclone separator in conjunction with a riser (wherein, the solid phase outlet of the cyclone separator is connected to the riser).

[0052] According to a preferred embodiment of the methane chemical chain hydrogen production method, the second oxygen carrier is treated using an overflow tank before being recycled for the second reaction.

[0053] The technical solution provided by this invention can balance methane conversion rate, CO2 capture efficiency, and hydrogen yield and purity. Compared with the prior art, the technical solution provided by this invention has the following beneficial effects:

[0054] 1. The technical solution provided by this invention employs a two-step method combined with two specific oxygen carriers for methane conversion. This method can fully convert methane into CO2, increasing the CO2 capture rate while lowering the reaction temperature, reducing carbon buildup on the oxygen carrier, and improving hydrogen purity. Furthermore, the equilibrium oxygen partial pressure required for water-to-hydrogen conversion is close to that required for syngas conversion, further improving the efficiency of the steam-to-hydrogen stage.

[0055] 2. The technical solution provided by this invention realizes the complete combustion of methane and the process of producing hydrogen from water. The two oxygen carriers circulate in their respective reaction regions, realizing the continuous operation of chemical chain hydrogen production from methane.

[0056] 3. The technical solution provided by this invention employs a combination of two oxygen carriers. For methane-to-syngas conversion, an oxygen carrier with strong methane CH bond activation ability and low equilibrium oxygen partial pressure is selected, enabling efficient methane conversion at lower temperatures. For the syngas-to-hydrogen process, an oxygen carrier with strong CO adsorption ability, weak CO bond breaking ability, and moderate equilibrium oxygen partial pressure (pO2 = 10) is selected. -19 -10 -16 The oxygen carrier can capture CO2 and prevent carbon buildup, thus improving the purity of hydrogen. Detailed Implementation

[0057] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0058] Example 1

[0059] This embodiment provides a method for producing hydrogen from methane through a chemical chain, wherein the method includes:

[0060] 1) Methane and the first oxygen carrier undergo a first reaction in a fluidized bed (including the reaction of methane and the first oxygen carrier in the main reaction zone using a bubbling fluidized bed, followed by a reaction in a riser section using a rapid fluidized bed); the product after the first reaction is separated into gas and solid phases using a cyclone separator and a riser (the solid outlet of the cyclone separator is connected to the riser), and the resulting gas phase product is syngas, and the solid phase product is the reduced first oxygen carrier;

[0061] The first oxygen carrier is selected from those with the chemical formula Fe. 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 An oxygen carrier for Al2O4; the first oxygen carrier can be prepared by the following process:

[0062] (1) Anhydrous citric acid is dissolved in deionized water to obtain an aqueous solution of citric acid; according to Fe 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 The stoichiometric ratio of Fe, Ni, Mn, Cu, Co, and Al in Al2O4 was determined by weighing out Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, Mn(NO3)2 aqueous solution, Cu(NO3)2·3H2O, Co(NO3)2·6H2O, and Al(NO3)3·9H2O, and dissolving them in an aqueous citric acid solution to prepare a precursor solution, wherein the molar ratio of anhydrous citric acid to the total amount of metal ions was 1.2:1.

[0063] (2) The precursor solution was evaporated to a gel state under stirring; then aged in a 130°C constant temperature drying oven for 12 hours to obtain precursor powder; the obtained precursor powder was calcined at 900°C in air atmosphere for 4 hours to obtain the first oxygen carrier Fe. 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 Al2O4.

[0064] The temperature of the first reaction is 1000℃; the pressure of the first reaction is atmospheric pressure.

[0065] The methane feed rate is 6000 mL / min, and the first oxygen carrier feed rate is 3000 g / min.

[0066] 2) After reduction, the first oxygen carrier is treated in an overflow tank and then contacted with air in a fluidized bed for oxidation (including the reaction of the reduced first oxygen carrier with air in the main reaction zone using a bubbling fluidized bed, followed by further reaction in a riser section using a rapid fluidized bed). The product after oxidation of the first oxygen carrier is separated into gas and solid phases using a cyclone separator and a riser (the solid phase outlet of the cyclone separator is connected to the riser). The resulting solid phase product is the first oxygen carrier. The prepared first oxygen carrier is then treated in an overflow tank and recycled for use in step 1).

[0067] The oxidation reaction of the reduced first oxygen carrier was carried out at a temperature of 1000℃ and a pressure of atmospheric pressure.

[0068] The air feed rate is 12000 mL / min.

[0069] 3) The synthesis gas obtained in step 1) and the second oxygen carrier are in countercurrent contact in a fluidized bed to carry out the second reaction; the solid product obtained from the second reaction is the reduced second oxygen carrier; the gaseous product obtained from the second reaction is treated by an overflow tank and then separated into gas and solid phases by a cyclone separator and a riser (the solid outlet of the cyclone separator is connected to the riser). The gaseous product CO2 and the solid product are obtained. The gaseous product CO2 is condensed and dehydrated for CO2 capture.

[0070] The second oxygen carrier is selected from those with the chemical formula LaAl. 1 / 4 Co 1 / 4 Mn 1 / 4 Fe 1 / 4 O3 oxygen carrier; the second oxygen carrier can be prepared by the following process:

[0071] (1) Anhydrous citric acid is dissolved in deionized water to obtain an aqueous solution of citric acid; according to LaAl 1 / 4 Co1 / 4 Mn 1 / 4 Fe 1 / The stoichiometric ratio of La, Al, Co, Mn, and Fe in 4O3 was determined by weighing out aqueous solutions of La(NO3)3·6H2O, Al(NO3)3·9H2O, Co(NO3)2·6H2O, Mn(NO3)2, and Fe(NO3)3·9H2O, and dissolving them in an aqueous solution of citric acid to prepare a precursor solution, wherein the molar ratio of anhydrous citric acid to the total amount of metal ions was 1.2:1.

[0072] (2) The precursor solution was evaporated to a gel state under stirring; then aged in a 130°C constant temperature drying oven for 12 hours to obtain precursor powder; the obtained precursor powder was calcined at 900°C in air atmosphere for 4 hours to obtain the second oxygen carrier LaAl. 1 / 4 Co 1 / 4 Mn 1 / 4 Fe 1 / 4 O3.

[0073] The temperature of the second reaction is 900℃; the pressure of the second reaction is atmospheric pressure.

[0074] In step 1), the syngas obtained is approximately 18,000 mL / min, and the feed rate of the second oxygen carrier is 9,000 g / min.

[0075] 4) The reduced second oxygen carrier obtained in step 3) is treated in an overflow tank and then contacted with water vapor in a fluidized bed to carry out the third reaction (including the reaction of the reduced second oxygen carrier and water vapor in the main reaction zone in the form of a bubbling fluidized bed, and then entering the riser section in the form of a fast fluidized bed to continue the reaction); the product after the third reaction is separated into gas and solid phases by a cyclone separator and a riser (the solid phase outlet of the cyclone separator is connected to the riser). The gas phase product is hydrogen and the solid phase product is the partially oxidized second oxygen carrier. The hydrogen gas phase product is collected after condensation.

[0076] The temperature of the third reaction is 900℃; the pressure of the third reaction is atmospheric pressure.

[0077] The steam feed rate is 30,000 mL / min, and the reduced second oxygen carrier obtained in step 3) is approximately 9,000 g / min.

[0078] 5) The partially oxidized second oxygen carrier obtained in step 4) is treated in an overflow tank and then reacted with the solid product obtained from the gas-solid separation in step 3) in a fluidized bed with air to carry out a complete oxidation reaction (including the reaction of the partially oxidized second oxygen carrier obtained in step 4) in an overflow tank and then reacted with the solid product obtained from the gas-solid separation in step 3) in a bubbling fluidized bed main reaction zone, and then entering a riser section in a fast fluidized bed form to continue the reaction); the product after the complete oxidation reaction is subjected to gas-solid separation using a cyclone separator in conjunction with a riser (the solid outlet of the cyclone separator is connected to the riser), and the obtained solid product is the second oxygen carrier; the obtained solid product, the second oxygen carrier, is treated in an overflow tank and then used in the second reaction;

[0079] The temperature for complete oxidation is 1000℃ and the pressure is atmospheric pressure.

[0080] The air feed rate is 12000 mL / min.

[0081] Comparative Example 1

[0082] This comparative example provides a method for producing hydrogen from methane through a chemical chain, wherein the difference between this method and Example 1 is that the first oxygen carrier is selected from the chemical formula LaAl. 1 / 4 Co 1 / 4 Mn 1 / 4 Fe 1 / 4 O3 oxygen carrier.

[0083] Comparative Example 2

[0084] This comparative example provides a method for producing hydrogen from methane via a chemical chain, wherein the difference between this method and Example 1 is that the second oxygen carrier is selected from those with the chemical formula Fe. 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 Oxygen carrier of Al2O4.

[0085] Example 2

[0086] This embodiment provides a method for producing hydrogen from methane through a chemical chain. The difference between this method and Example 1 is that the first reaction temperature is 900°C and the feed rate of the first oxygen carrier is 4000 g / min.

[0087] Example 3

[0088] This embodiment provides a method for producing hydrogen from methane through a chemical chain, wherein the difference between this method and Example 1 is that the first reaction temperature is 950°C and the third reaction temperature is 950°C.

[0089] Example 4

[0090] This embodiment provides a method for producing hydrogen from methane through a chemical chain. The difference between this method and Example 1 is that the second reaction temperature is 950°C, the feed rate of the second oxygen carrier is 12000 g / min, and the third reaction temperature is 950°C.

[0091] The CH4 conversion, CO2 selectivity, H2 yield, and H2 purity of each embodiment and comparative example are shown in Table 1 below.

[0092] Table 1

[0093]

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. All claims within the spirit and principles of the present invention shall be deemed to be in accordance with the present invention.

Claims

1. A method for producing hydrogen from methane through a chemical chain, wherein, The method includes: Methane is reacted with a first oxygen carrier to undergo a first reaction, producing syngas and a reduced first oxygen carrier; wherein the first oxygen carrier is selected with the chemical formula Fe. 0.2 Ni 0.2 Mn 0.2 Cu 0.2 Co 0.2 An oxygen carrier for Al2O4; The syngas obtained from the first reaction is contacted with the second oxygen carrier to carry out a second reaction, producing CO2 and the reduced second oxygen carrier; wherein the second oxygen carrier is selected with the chemical formula LaAl. 1 / 4 Co 1 / 4 Mn 1 / 4 Fe 1 / 4 O3 oxygen carrier; The reduced second oxygen carrier is contacted with water vapor to carry out a third reaction, producing hydrogen and a partially oxidized second oxygen carrier; The partially oxidized second oxygen carrier is subjected to a complete oxidation reaction to obtain a second oxygen carrier, which is then recycled for use in the second reaction.

2. The method according to claim 1, wherein, The temperature of the first reaction is 900-1100℃; the pressure of the first reaction is 0.1-0.3MPa.

3. The method according to claim 1, wherein, The ratio of methane to the first oxygen carrier is 1-3 mL: 1 g.

4. The method according to any one of claims 1-3, wherein, Methane reacts with a first oxygen carrier to undergo a first reaction, producing syngas and a reduced first oxygen carrier, including: Methane and the first oxygen carrier come into contact in a fluidized bed to carry out the first reaction; The products after the first reaction are subjected to gas-solid separation. The gas phase product obtained is the synthesis gas, and the solid phase product is the reduced first oxygen carrier. The first reaction, in which methane contacts the first oxygen carrier in a fluidized bed, includes: After reacting with the first oxygen carrier in the main reaction zone, methane enters the riser section to continue the reaction; the main reaction zone adopts a bubbling fluidized bed or a turbulent fluidized bed, and the riser section adopts a fast fluidized bed.

5. The method according to claim 1, wherein, The method also includes: The reduced first oxygen carrier was subjected to a complete oxidation reaction to prepare the first oxygen carrier. The prepared first oxygen carrier was then used in the first reaction.

6. The method according to claim 5, wherein, The oxidation reaction of the reduced first oxygen carrier is carried out at a temperature of 900-1100℃; the pressure of the reduced first oxygen carrier is 0.1-0.3MPa.

7. The method according to claim 5 or 6, wherein, The reduced first oxygen carrier is subjected to an oxidation reaction to prepare the first oxygen carrier, which includes: The reduced first oxygen carrier is contacted with the first oxidizing gas in a fluidized bed to carry out an oxidation reaction; wherein, the first oxidizing gas is air; the product after the oxidation reaction of the first oxygen carrier is subjected to gas-solid separation, and the solid product obtained is the first oxygen carrier. The oxidation reaction between the reduced first oxygen carrier and the first oxidizing gas in the fluidized bed includes: the reduced first oxygen carrier and the first oxidizing gas react in the main reaction zone and then enter the riser section to continue the reaction; wherein the main reaction zone adopts the form of a bubbling fluidized bed or a turbulent fluidized bed, and the riser section adopts the form of a fast fluidized bed.

8. The method according to claim 1, wherein, The temperature of the second reaction is 800-900℃; the pressure of the second reaction is 0.1-0.3MPa.

9. The method according to claim 1, wherein, The ratio of the synthesis gas obtained from the first reaction to the second oxygen carrier is 1-3 mL: 1 g.

10. The method according to any one of claims 1, 8, and 9, wherein, The syngas obtained from the first reaction is contacted with the second oxygen carrier to carry out a second reaction, producing CO2 and the reduced second oxygen carrier, including: The syngas obtained from the first reaction comes into contact with the second oxygen carrier in a fluidized bed through countercurrent flow to carry out the second reaction; The solid product obtained from the second reaction is the reduced second oxygen carrier. The gaseous product obtained from the second reaction is treated in an overflow tank and then subjected to gas-solid separation. The resulting gaseous product is CO2.

11. The method according to claim 10, wherein, The method further includes: subjecting the gaseous product obtained from the second reaction to gas-solid separation after treatment in an overflow tank, and then subjecting the solid product obtained to the partially oxidized second oxygen carrier to a complete oxidation reaction to obtain the second oxygen carrier.

12. The method according to claim 1, wherein, The temperature of the third reaction is 850-950℃; the pressure of the third reaction is 0.1-0.3MPa.

13. The method according to claim 1, wherein, The ratio of water vapor to the reduced second oxygen carrier is 5-10 mL: 1 g.

14. The method according to any one of claims 1, 12, and 13, wherein, The reduced second oxygen carrier is contacted with water vapor to undergo a third reaction, producing hydrogen and a partially oxidized second oxygen carrier, including: The reduced second oxygen carrier comes into contact with water vapor in a fluidized bed to carry out a third reaction; The product after the third reaction is subjected to gas-solid separation. The gas phase product is hydrogen, and the solid phase product is the partially oxidized second oxygen carrier. The third reaction, in which the reduced second oxygen carrier contacts water vapor in a fluidized bed, includes: After reduction, the second oxygen carrier reacts with water vapor in the main reaction zone and then enters the riser section to continue the reaction. The main reaction zone adopts a bubbling fluidized bed or a turbulent fluidized bed, while the riser section adopts a rapid fluidized bed.

15. The method according to claim 1, wherein, During the complete oxidation reaction of the partially oxidized second oxygen carrier, the reaction temperature is 900-1100℃ and the reaction pressure is 0.1-0.3MPa.

16. The method according to claim 1 or 15, wherein, The process of completely oxidizing a partially oxidized second oxygen carrier to obtain a second oxygen carrier, and recycling the second oxygen carrier for a second reaction, includes: The partially oxidized second oxygen carrier and the second oxidizing gas come into contact in a fluidized bed to carry out a complete oxidation reaction; wherein, the first oxidizing gas is air. The product after the oxidation reaction is subjected to gas-solid separation, and the resulting solid product is the second oxygen carrier. The partial oxidation of the second oxygen carrier and the second oxidizing gas in the fluidized bed to carry out a complete oxidation reaction includes: The partially oxidized second oxygen carrier reacts with the second oxidizing gas in the main reaction zone and then enters the riser section to continue the reaction; the main reaction zone adopts the form of a bubbling fluidized bed or a turbulent fluidized bed, and the riser section adopts the form of a fast fluidized bed.

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