Oxygen carrier for chemical looping hydrogen production and preparation method therefor, and multi-stage coupled chemical looping hydrogen production method

Abstract

Disclosed in the present invention is an oxygen carrier for chemical looping hydrogen production, for use in a multi-stage coupled chemical looping hydrogen production device. The oxygen carrier comprises an active component and an inactive component, wherein the active component comprises one or more of NiO, CuO, and ZnO, and the inactive component comprises one or more of ZrO2, MgO, Y2O3, stable zirconium oxide, MgAl2O4, CaAl2O4, CaO, Al2O3, and TiO2. The weight of the active component accounts for 10-25% of the total weight of the active component and the inactive component, and the weight of the inactive component accounts for 75-90% of the total weight of the active component and the inactive component. The particle size of the active component ranges from 5 nm to 5 μm, and the particle size of the inactive component ranges from 5 nm to 5 μm. The oxygen carrier for chemical looping hydrogen production of the present invention has a relatively low production cost, does not generate pollutants during the preparation process, and can be widely used in chemical looping hydrogen production. Moreover, the oxygen carrier has good weight recovery and high average weight loss during repeated reactions.

Description

An oxygen carrier for chemical chain hydrogen production, its preparation method, and a multi-stage coupled chemical chain hydrogen production method. Technical Field

[0001] This invention relates to the field of chemical chain hydrogen production technology, and in particular to an oxygen carrier for chemical chain hydrogen production, its preparation method, and a multi-stage coupled chemical chain hydrogen production method. Background Technology

[0002] Chemical looping hydrogen production (CLP) is a method for producing hydrogen using chemical looping technology. It combines fuel with an oxygen carrier through a specific reaction process, achieving efficient fuel utilization and CO2 capture. CLP is characterized by its high efficiency, cleanliness, and economy, while the preparation and selection of the oxygen carrier are crucial to its success. The oxygen carrier plays a vital role in transferring oxygen and heat in CLP, therefore its performance directly affects the operation of the entire system. This necessitates high reactivity and high multi-cycle stability of the oxygen carrier. The composition, preparation method, and parameters of the oxygen carrier are the two most important factors influencing its final performance.

[0003] The Chinese invention patent application number 202410022173.7 filed by the applicant discloses a novel multi-stage coupled chemical chain hydrogen production device and method, the most significant feature of which is that it includes two chemical chain cycle units: a first chemical chain reaction unit and a second chemical chain reaction unit. The patent discloses oxygen carriers used in the two chemical chain reaction units respectively: namely, a first oxygen carrier (corresponding to the first chemical chain reaction, water vapor oxidation-reduction process) and a second oxygen carrier (corresponding to the second chemical chain reaction, the first reduction tail gas reduction-oxidation process).

[0004] The invention patent also describes that the first oxygen carrier contains active components such as Fe3O4, and selectively contains one or more of the following: secondary active components (MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2) or inactive components (Al2O3, ZrO2, Y2O3, MgAl2O4, CaAl2O4, TiO2, CaO) or both; and describes that the second oxygen carrier contains active components (one or more of NiO, CuO, ZnO), and selectively contains one or more of the following: secondary active components (Fe2O3, CeO2, Co3O4, Mn2O3) or inactive components (ZrO2, MgO, Y2O3, MgAl2O4, CaAl2O4, CaO, Al2O3, TiO2) or both.

[0005] In addition, the second oxygen carrier is usually prepared by impregnation or co-precipitation. This method involves impregnating the surface of an inert porous support with a nickel salt solution and then calcining it at high temperature to form a composite oxygen carrier with nickel oxide loaded on the surface of the inert porous support material. However, this method not only generates a large amount of nitrogen oxides during calcination, polluting the environment, but also limits the maximum loading of nickel salts by the impregnation method. Multiple impregnation and calcination steps are required to obtain an oxygen carrier with a nickel loading of more than 10 wt.%. The whole process is highly polluting and energy-intensive, ultimately resulting in high preparation costs. Summary of the Invention

[0006] In view of this, based on the aforementioned Chinese invention application with application number 202410022173.7, the inventors have further devoted themselves to research and, through examples and experimental results, identified a more preferred range and composition combination for the second oxygen carrier; at the same time, in the process of manufacturing the second oxygen carrier, a preferred manufacturing process was discovered, and thus the present invention was completed.

[0007] The purpose of this invention is to provide an oxygen carrier (second oxygen carrier) for chemical chain hydrogen production that can maintain high reactivity and high cycling stability, its manufacturing method, and a multi-stage coupled chemical chain hydrogen production method using the oxygen carrier.

[0008] To achieve the above objectives, the technical solution of the present invention is: an oxygen carrier for chemical loop hydrogen production in a multi-stage coupled chemical loop hydrogen production device.

[0009] It includes active and inactive components. The active components include one or more of NiO, CuO, and ZnO, and the inactive components include one or more of ZrO2, MgO, Y2O3, stabilized zirconium oxide, MgAl2O4, CaAl2O4, CaO, Al2O3, and TiO2.

[0010] The active component accounts for 10-25% of the total weight of the active and inactive components; the inactive component accounts for 75-90% of the total weight of the active and inactive components.

[0011] The particle size range of the active component is 5 nm to 5 μm, and the particle size range of the inactive component is 5 nm to 5 μm.

[0012] Furthermore, the oxygen carrier also includes a secondary active component, which is one or more of Fe2O3, CeO2, Co3O4 and Mn2O3; wherein the weight of the secondary active component accounts for 0 to 5% of the total weight of the active component, the secondary active component and the inactive component; and the particle size range of the secondary active component is 5 nm to 5 μm.

[0013] Furthermore, the stabilized zirconium oxide includes one or more of magnesium-stabilized zirconium oxide, yttrium-stabilized zirconium oxide, calcium-stabilized zirconium oxide, and cerium-stabilized zirconium oxide.

[0014] Furthermore, the active component is NiO, and the inactive component includes one or more of ZrO2, MgAl2O4, and CaAl2O4.

[0015] Furthermore, the active component is NiO, and the inactive component includes ZrO2; the weight of NiO accounts for 10-25% of the total weight of NiO and ZrO2, and the weight of ZrO2 accounts for 75-90% of the total weight of NiO and ZrO2.

[0016] Furthermore, the particle size of NiO is 500 nm; the particle size of ZrO2 is 500 nm.

[0017] Furthermore, the particle size range of the active component is 5 nm to 500 nm, and the particle size range of the inactive component is 5 nm to 500 nm.

[0018] Furthermore, the particle size range of the secondary active component is 5 nm to 500 nm.

[0019] The present invention also provides the following method for preparing oxygen carrier:

[0020] The preparation method includes the following steps:

[0021] S10. Mix the active component, the secondary active component, and the inactive component in a certain proportion to obtain a mixture powder;

[0022] S20. Granulate the powder into shape;

[0023] S30. The granulated particles are placed in a heating furnace for heat treatment. After heat treatment, they are cooled to obtain the final oxygen carrier.

[0024] Furthermore, step S15 is included between steps S10 and S20: the obtained mixture powder is placed in a heating furnace for heat treatment, and after the heat treatment is completed, it is cooled to obtain the first powder.

[0025] Furthermore, in step S10, the weight of the active component accounts for 10-25% of the total weight of the active component, the secondary active component, and the inactive component; the weight of the secondary active component accounts for 0-5% of the total weight of the active component, the secondary active component, and the inactive component; and the weight of the inactive component accounts for 75-90% of the total weight of the active component, the secondary active component, and the inactive component.

[0026] Furthermore, in step S15, when the mixed powder is heat-treated in the heating furnace, the heating process adopts programmed heating with a heating rate of 10-35℃ / min. After the temperature reaches the set temperature, it is maintained for 5-15 hours. The set temperature is a specific temperature within the range of 900-1250℃.

[0027] Furthermore, in step S20, mechanical granulation is used to granulate the particles, resulting in particles with a kinetic equivalent diameter of 2 mm to 9 mm.

[0028] Furthermore, in step S30, when the granulated particles are heat-treated in a heating furnace, the heating process adopts a programmed heating method with a heating rate of 10 to 35 / min. After the temperature reaches the set temperature, it is maintained for 5 to 15 hours. The set temperature is a specific temperature within the range of 850 to 1350℃.

[0029] The present invention further provides a multi-stage coupled chemical chain hydrogen production method:

[0030] The multi-stage coupled chemical chain hydrogen production method uses the following multi-stage coupled chemical chain hydrogen production apparatus:

[0031] The multi-stage coupled chemical chain hydrogen production device includes a first chemical chain reaction unit and a second chemical chain reaction unit.

[0032] The first chemical chain reaction unit includes a first-stage reducer and a steam oxidation hydrogen generator. These two parts can be converted into each other according to the reaction stage and can be cyclically repeated as a whole.

[0033] The second chemical chain reaction unit includes a second-stage reducer, a methane converter, and an air oxidizer. These three parts can be interchanged according to the reaction stage and can be cyclically repeated as a whole.

[0034] The same first oxygen carrier is provided in the first stage reducer and the steam oxidation hydrogen generator. The first oxygen carrier changes into a metal element or a metal oxide with different chemical valences in each reaction stage. The metal has multiple chemical valences.

[0035] The same second oxygen carrier is provided in the second stage reducer, the methane converter and the air oxidizer. The second oxygen carrier changes into a metal element or a metal oxide with different chemical valence in each reaction stage, and the metal element corresponding to the second oxygen carrier acts as a catalyst in the methane conversion reaction in the methane conversion reactor.

[0036] The methane converter is connected to the first stage reducer and is used to supply the syngas after methane conversion to the first stage reducer.

[0037] The second-stage reducer is connected to the methane converter and is used to reflux carbon dioxide or water vapor or both to the methane converter.

[0038] The first stage reducer is connected to the second stage reducer and is used to supply the second stage reducer with reducing tail gas containing carbon monoxide or hydrogen or both.

[0039] The multi-stage coupled chemical chain hydrogen production method includes the following steps:

[0040] The device startup and oxygen carrier and reactor preparation steps include starting the multi-stage coupled chemical chain hydrogen production device, filling the two reactors corresponding to the first chemical chain reaction unit with the first oxygen carrier, and filling the three reactors corresponding to the second reaction chain unit with the second oxygen carrier.

[0041] In the reactor pretreatment step, all five reactors are heated and the system is adjusted to be suitable for the following reactions through a combination of pre-reduction and pre-oxidation: the first reduction reaction and the steam oxidation hydrogen production reaction are repeated in a cycle between the two reactors corresponding to the first chemical chain reaction unit; and the second reduction reaction, the methane conversion reaction and the air oxidation reaction are repeated in a cycle between the three reactors corresponding to the second chemical chain reaction unit.

[0042] In the methane conversion step, a combustible gas containing methane is introduced into the methane converter. It is first mixed with the reduction tail gas recycled from the second stage reducer. Then, the methane and the mixed gas containing CO2 or H2O or both undergo a methane conversion reaction under the catalysis of elemental metal. The heat accumulated in the oxygen carrier during the air oxidation step is fully utilized to generate syngas containing CO, H2, CO2, and H2O, which enters the first stage reducer of the first stage chemical chain reaction unit.

[0043] In the air oxidation step, after the methane conversion reaction is completed, the reactor is switched to the air oxidizer state and the air oxidation process is carried out. That is, air or oxygen is introduced into the air oxidizer to oxidize the metal elemental oxygen carrier to a high oxidation state and release a large amount of reaction heat. Most of this reaction heat is stored in the oxidized oxygen carrier bed, which stores the heat required for the subsequent methane conversion process in advance.

[0044] In the second reduction step, after air oxidation is completed, the reactor is switched to the second-stage reducer state and the second-stage reduction process is carried out. That is, the remaining CO and H2 in the tail gas of the first-stage reduction reduce the second oxygen carrier in the second-stage reducer from the high-valence oxide state to the elemental state. At the same time, CO and H2 are completely oxidized to CO2 and H2O. By controlling and adjusting the switching time, it is ensured that the second-stage reduction process does not penetrate, so that the tail gas of the second-stage reduction is entirely CO2 and H2O. Furthermore, a portion of the tail gas is returned to the methane converter and mixed with the methane-containing fuel gas to carry out the methane conversion reaction. The heat of the remaining portion is recovered, and the H2O is condensed to obtain high-purity CO2, which is then captured.

[0045] In the first reduction step, syngas containing CO and H2, generated by the methane converter, is introduced into the first reducer. The second-highest valence metal oxide state of the oxygen carrier is reduced by CO and H2 in the syngas to a lower valence metal oxide or metal element. The syngas is partially oxidized by the oxygen carrier in the first chemical chain reaction to generate a mixed gas containing unreacted residual CO and H2, as well as CO2 and H2O, which is the first reduction tail gas. This gas is then returned to the second reducer in the second chemical chain reaction unit.

[0046] In the steam oxidation hydrogen production step, steam is introduced into the steam oxidation hydrogen generator to oxidize the low-valence metal oxide oxygen carrier or metal element produced in the first reduction step to the second-highest valence oxidation state, while producing high-purity hydrogen.

[0047] The multi-stage coupled chemical chain hydrogen production device includes a first chemical chain reaction unit and a second chemical chain reaction unit.

[0048] The first chemical chain reaction unit includes a first-stage reducer and a steam oxidation hydrogen generator. These two parts can be converted into each other according to the reaction stage and can be cyclically repeated as a whole.

[0049] The second chemical chain reaction unit includes a second-stage reducer, a methane converter, and an air oxidizer. These three parts can be interchanged according to the reaction stage and can be cyclically repeated as a whole.

[0050] The same oxygen carrier is provided in the first stage reducer and the steam oxidation hydrogen generator. The oxygen carrier changes into a metallic element or a metal oxide with different chemical valences in each reaction stage. The metal has multiple chemical valences.

[0051] The same second oxygen carrier is provided in the second stage reducer, the methane converter and the air oxidizer. The second oxygen carrier changes into a metal element or a metal oxide with different chemical valence in each reaction stage, and the metal element corresponding to the second oxygen carrier acts as a catalyst in the methane conversion reaction in the methane conversion reactor.

[0052] The methane converter is connected to the first stage reducer and is used to supply the syngas after methane conversion to the first stage reducer.

[0053] The second-stage reducer is connected to the methane converter and is used to reflux carbon dioxide or water vapor or both to the methane converter.

[0054] The first stage reducer is connected to the second stage reducer and is used to supply the second stage reducer with reducing tail gas containing carbon monoxide or hydrogen or both.

[0055] The second oxygen carrier is used in the first stage of the reduction and oxidation process of the tail gas, which is the second stage of the chemical chain reaction.

[0056] It includes active and inactive components. The active components include one or more of NiO, CuO, and ZnO, and the inactive components include one or more of ZrO2, MgO, Y2O3, stabilized zirconium oxide, MgAl2O4, CaAl2O4, CaO, Al2O3, and TiO2.

[0057] The active component accounts for 10-25% of the total weight of the active and inactive components; the inactive component accounts for 75-90% of the total weight of the active and inactive components.

[0058] The particle size range of the active component is 5 nm to 5 μm, and the particle size range of the inactive component is 5 nm to 5 μm.

[0059] Furthermore, the stabilized zirconium oxide includes one or more of magnesium-stabilized zirconium oxide, yttrium-stabilized zirconium oxide, calcium-stabilized zirconium oxide, and cerium-stabilized zirconium oxide.

[0060] Furthermore, the second oxygen carrier also includes a secondary active component, which is one or more of Fe2O3, CeO2, Co3O4 and Mn2O3; wherein the weight of the secondary active component accounts for 0 to 5% of the total weight of the active component, the secondary active component and the inactive component; and the particle size range of the secondary active component is 5 nm to 5 μm.

[0061] Thus, the present invention provides a preferred combination of components and chemical components of the second oxygen carrier; it also provides a method for preparing a second oxygen carrier that has low manufacturing cost, does not generate pollutants during preparation, can be widely used in chemical chain hydrogen production, has good weight recovery during repeated reactions, and has a high average weight loss, as well as a multi-stage coupled chemical chain hydrogen production method using the second oxygen carrier. Attached Figure Description

[0062] Figure 1 is a flowchart of the preparation method of the oxygen carrier for chemical chain hydrogen production in this invention.

[0063] Figure 2 shows the redox thermogravimetric results of the second oxygen carrier A in this application.

[0064] Figure 3 shows the redox thermogravimetric results of the second oxygen carrier B in this application.

[0065] Figure 4 shows the redox thermogravimetric results of the second oxygen carrier C in this application.

[0066] Figure 5 is a schematic diagram showing the structure of the multi-stage coupled chemical chain hydrogen production device of the present invention. Detailed Implementation

[0067] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings. First, with reference to FIG5, the multi-stage coupled chemical chain hydrogen production apparatus and method using the second oxygen carrier of the present invention will be described. Second, with reference to FIG1, the manufacturing process of the second oxygen carrier of the present invention will be described. Finally, with reference to FIG2, 3, and 4, the preferred second oxygen carrier of the present invention and its manufacturing method will be described.

[0068] (Description of the multi-stage coupled chemical chain hydrogen production device and method of the present invention)

[0069] Figure 5 is a schematic diagram illustrating the structure of a multi-stage coupled chemical chain hydrogen production device according to an embodiment of the present invention. As shown in Figure 5, the multi-stage coupled chemical chain hydrogen production device of the present invention includes a first chemical chain reaction unit indicated by the upper box and a second chemical chain reaction unit indicated by the lower box.

[0070] The second chemical chain reaction unit includes a second-stage reducer, a methane converter, and an air oxidizer. These three parts can be converted into each other according to the reaction stage and can be cyclically repeated as a whole.

[0071] In the second-stage reducer, methane converter, and air oxidizer, a metal oxide (represented by metal M) is used as an oxygen carrier in the reduction-oxidation reaction (hereinafter referred to as the "second oxygen carrier"). This metal M must be selected as a metal that can act as a catalyst in the methane conversion reaction, and at the same time, it should be a metal that can fully accumulate heat through the redox reaction.

[0072] The second oxygen carrier comprises an active component and an inactive component, and selectively includes a secondary active component. The active component includes one or more of NiO, CuO, and ZnO; the secondary active component includes one or more of Fe2O3, CeO2, Co3O4, and Mn2O3, but is not limited thereto; the inactive component includes one or more of ZrO2, MgO, Y2O3, MgAl2O4, CaAl2O4, CaO, Al2O3, and TiO2. Here, the main function of the active component is to act as an oxygen carrier in the redox cycle and to catalyze the methane conversion process; the main function of the secondary active component is to enhance and stabilize the performance of the active component; and the main function of the inactive component is to make the reaction of the second oxygen carrier more stable, avoid sintering, achieve a reasonable pore structure, and achieve a better heat storage structure (thereby fully storing heat during air oxidation and fully releasing heat during catalysis).

[0073] The second-stage reducer, methane converter, and air oxidizer utilize multiple pipelines and valves installed on these pipelines to achieve inter-functional switching between the three reaction units. For example, when the three reactors corresponding to the second-stage reducer, methane converter, and air oxidizer are defined as reactor B, reactor A, and reactor C, after system preheating and entering the circulation system, initially reactor A functions as the methane converter, reactor B as the second-stage reducer, and reactor C as the air oxidizer. However, after switching the pipeline via valves, reactor A functions as the air oxidizer, reactor B as the methane converter, and reactor C as the second-stage reducer. Then, after switching the pipeline again via valves, reactor A functions as the second-stage reducer, reactor B as the air oxidizer, and reactor C as the methane converter, and so on, in a continuous cycle.

[0074] The following describes a multi-stage coupled chemical chain hydrogen production method using the multi-stage coupled chemical chain hydrogen production apparatus of the present invention.

[0075] As shown in Figure 5, when using the multi-stage coupled chemical chain hydrogen production device of the present invention for hydrogen production, the first step is to start up the device and prepare the oxygen carrier and reactors. Specifically, in the five reactors (A / B / C / D / E) of the multi-stage coupled chemical chain hydrogen production device, the first oxygen carrier is filled into reactors D and E corresponding to the first chemical chain reaction unit, and the second oxygen carrier is filled into reactors A / B / C corresponding to the second reaction chain unit. The oxidation state of the active metal component of the initially filled oxygen carrier can be the working oxidation state used in the actual redox cycle, or it can be another oxidation state (adjusted to the working oxidation state using the first redox cycle after actual operation). For example, although the active component in the first oxygen carrier is Fe3O4 after the cycle starts, Fe2O3 can be used in the initially filled oxygen carrier.

[0076] Next, all five reactors (A / B / C / D / E) are heated to the specified temperature.

[0077] After the three reactors (A / B / C) in the second chemical chain unit have undergone oxygen carrier pre-reduction preparation, H2 is introduced into the three reactors (A / B / C) to begin the oxygen carrier pre-reduction. Once all reactors have completed pre-reduction, air is introduced into one of the reactors, A, for air oxidation and heat storage. After reactor A has completed air oxidation and heat storage, it switches to H2 reduction and continues to accumulate heat; simultaneously, another reactor, B, undergoes air oxidation.

[0078] After hydrogen reduction and heat storage, reactor A is introduced with CH4 combustible gas to carry out methane conversion and produce syngas containing CO and H2; at the same time, reactor B switches to oxygen carrier reduction, and the reducing gas comes from the tail gas of the first chemical loop unit (containing through CO and H2); at the same time, reactor C carries out air oxidation.

[0079] Reactor A, which has completed the methane conversion, is switched to the air oxidation process to perform air oxidation and generate and store heat; reactor B is switched to the methane conversion process; and reactor C is switched to the oxygen carrier reduction process.

[0080] After completing air oxidation, reactor A switches to oxygen carrier reduction; after completing methane conversion, reactor B switches to air oxidation; reactor C then switches to methane conversion.

[0081] The subsequent processes of the second chemical chain unit are cyclically switched between three reactors (A / B / C).

[0082] On the other hand, the syngas enters reactor D in the two reactors (D / E) of the first chemical chain unit, where the first oxygen carrier is reduced. The reduction tail gas (containing penetrating CO and H2) returns to the reactor (second reducer) in the second chemical chain unit, which is in a reduced state, to reduce the second oxygen carrier.

[0083] Reactor D, having completed the reduction of the first oxygen carrier, switches to steam oxidation for hydrogen production and completes the steam oxidation reaction. Simultaneously, syngas is introduced into reactor E to carry out the reduction reaction of the first oxygen carrier. Next, reactor D, having completed steam oxidation of the oxygen carrier for hydrogen production, switches to oxygen carrier reduction, and reactor E, having completed reduction, switches to steam oxidation for hydrogen production, and the above cycle is repeated.

[0084] (Description of the first oxygen carrier for chemical chain hydrogen production of the present invention and its preparation method)

[0085] Figure 1 is a flowchart of the preparation method of the oxygen carrier for chemical chain hydrogen production in this invention. As shown in Figure 1, this invention proposes an oxygen carrier material and a method for large-scale preparation in the chemical chain hydrogen production process. This oxygen carrier is used, but is not limited to, the second stage chemical chain reaction unit mentioned in the aforementioned patent application 202410022173.7. It can also be used in the three-cycle process of "oxygen carrier reduction - methane reforming conversion - oxygen carrier air oxidation" in other independently carried out chemical chain hydrogen production or chemical chain reforming processes.

[0086] The composition of the second oxygen carrier may be as follows, but is not limited to:

[0087] The active component is one or more of NiO, CuO and ZnO;

[0088] Selectively includes one or more of the following secondary active components: Fe2O3, CeO2, Co3O4, and Mn2O3;

[0089] It contains one or more of the following inactive components: ZrO2, MgO, Y2O3, stabilized zirconium oxide (including one or more of magnesium-stabilized zirconium oxide, yttrium-stabilized zirconium oxide, calcium-stabilized zirconium oxide and cerium-stabilized zirconium oxide), MgAl2O4, CaAl2O4, CaO, Al2O3 and TiO2;

[0090] The active component accounts for 10-25% of the total weight of the active component, the secondary active component, and the inactive component; the secondary active component accounts for 0-5% of the total weight of the active component, the secondary active component, and the inactive component; and the inactive component accounts for 75-90% of the total weight of the active component, the secondary active component, and the inactive component.

[0091] The particle size range of the active component is 5 nm to 5 μm; the particle size range of the secondary active component is 5 nm to 5 μm; and the particle size range of the inactive component is 5 nm to 5 μm.

[0092] The second oxygen carrier can be prepared by the following methods, but is not limited to these:

[0093] (1) Mix the active components, the non-active components, or the selectively active components, and the inactive components in a certain proportion to obtain a mixture powder.

[0094] (2) Optionally, the obtained mixture powder is placed in a heating furnace for heat treatment. The heating process adopts a programmed heating rate of 10-35℃ / min. After reaching the specified temperature (a specific temperature in the range of 900-1250℃), it is maintained for 5-15 hours and then cooled to obtain the first powder.

[0095] (3) The mixture powder or the first powder is granulated to obtain particles with a kinetic equivalent diameter of 2 mm to 9 mm.

[0096] (4) After granulation, the granules are placed in a heating furnace for heat treatment. The heating process adopts a programmed heating rate of 10-35℃ / min. After reaching the specified temperature (a specific temperature within the range of 850-1350℃), it is maintained for 5-15 hours. After cooling, the final oxygen carrier is obtained.

[0097] The embodiments of the second oxygen carrier of the present invention will now be described in detail.

[0098] (Example 1: Preparation of the second oxygen carrier A)

[0099] The present invention uses the following method to manufacture the second oxygen carrier A.

[0100] (1) NiO powder with a particle size of 500nm and ZrO2 powder with a particle size of 500nm were placed in a drying oven and dried at 105℃ to constant weight. 180g and 820g of the dried powder were weighed and mixed thoroughly to obtain a mixture powder.

[0101] (2) The obtained mixture powder is placed in a heating furnace and heated to 1150°C at a heating rate of 15°C / min, maintained for 9 hours, and then cooled to obtain the first powder.

[0102] (3) The first powder is mechanically granulated to obtain columnar particles with a size of φ4mm*H6mm (kinetic equivalent diameter of about 4.8mm).

[0103] (4) After granulation, the granules are placed in a heating furnace and heated to 1150°C at a heating rate of 15°C / min. The temperature is maintained for 9 hours and then cooled to obtain the final oxygen carrier.

[0104] Figure 2 shows the continuous test results of the weight loss rate of the second oxygen carrier A during repeated redox processes. As shown in Figure 2, the weight change of the second oxygen carrier A during repeated redox processes is reproducible, and the average maximum weight loss rate for each cycle is measured to be 4.1%.

[0105] (Example 2: Preparation of the second oxygen carrier B)

[0106] The present invention uses the following method to manufacture the second oxygen carrier B.

[0107] (1) NiO powder with a particle size of 500 nm and ZrO2 powder with a particle size of 500 nm were placed in a drying oven and dried at 105 °C to constant weight to obtain a mixed powder.

[0108] (2) The obtained mixture powder is placed in a heating furnace and heated to 1100℃ at a heating rate of 15℃ / min, maintained for 9h, and then cooled to obtain the first powder.

[0109] (3) The first powder is granulated to obtain spherical particles with a diameter of 5 mm.

[0110] (4) After granulation, the granules are placed in a heating furnace and heated to 1100°C at a heating rate of 15°C / min. The temperature is maintained for 9 hours and then cooled to obtain the final oxygen carrier.

[0111] Figure 3 shows the continuous test results of the weight loss rate of the second oxygen carrier B during repeated redox processes. As shown in Figure 3, the weight change of the second oxygen carrier B during repeated redox processes is reproducible, and the average maximum weight loss rate for each cycle is measured to be 2.5%.

[0112] (Example 3: Preparation of the second oxygen carrier C)

[0113] The present invention uses the following method to manufacture the second oxygen carrier C.

[0114] (1) NiO powder with a particle size of 50 nm and MgAl2O4 powder with a particle size of 500 nm were placed in a drying oven and dried at 105 °C to constant weight. 200 g and 1050 g of the dried powder were weighed and mixed thoroughly to obtain a mixture powder.

[0115] (2) The obtained mixture powder is placed in a heating furnace and heated to 1200℃ at a heating rate of 15℃ / min, maintained for 9h, and then cooled to obtain the first powder.

[0116] (3) The first powder is granulated to obtain spherical particles with a diameter of 6 mm.

[0117] (4) After granulation, the granules are placed in a heating furnace and heated to 1200°C at a heating rate of 15°C / min. The temperature is maintained for 9 hours and then cooled to obtain the final oxygen carrier.

[0118] Figure 4 shows the continuous test results of the weight loss rate of the third oxygen carrier C during repeated redox processes. As shown in Figure 4, the weight change of the second oxygen carrier C showed good repeatability during repeated redox processes, and the average maximum weight loss rate for each cycle was measured to be 3.5%.

[0119] (Results and analysis of Examples 1-3)

[0120] The table below summarizes the specific data of the active and inactive components in Examples 1 to 3 above, as well as the average value of the maximum weight loss rate for each cycle.

[0121] As can be seen from the table above, the weight change repeatability of the second oxygen carriers in Examples 1 to 3 of the present invention is good when repeated redox reactions are carried out. Furthermore, considering the average value of the maximum weight loss rate in each cycle, Example 1 has the largest value, which indicates that the second oxygen carrier A in Example 1 is the most active in the redox process and is the preferred embodiment.

[0122] (Examples 4, 5, and 6: Preparation of second oxygen carriers D, E, and F)

[0123] The second oxygen carriers D, E, and F were manufactured using the methods described in Examples 4, 5, and 6 of this invention. The repeatability of weight changes during repeated reactions and the average maximum weight loss rate for each cycle are as follows:

[0124] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

An oxygen carrier for a multi-stage coupled chemical looping hydrogen production device, characterized in that, it comprises an active component and a non-active component, the active component comprises one or more of NiO, CuO and ZnO, and the non-active component comprises one or more of ZrO2, MgO, Y2O3, stabilized zirconia, MgAl2O4, CaAl2O4, CaO, Al2O3 and TiO2, wherein the weight of the active component accounts for 10-25% of the total weight of the active component and the non-active component; the weight of the non-active component accounts for 75-90% of the total weight of the active component and the non-active component; the particle size of the active component ranges from 5nm to 5μm, and the particle size of the non-active component ranges from 5nm to 5μm. The oxygen carrier for chemical looping hydrogen production according to claim 1, characterized in that, it further comprises a sub-active component, which is one or more of Fe2O3, CeO2, Co3O4 and Mn2O3; wherein the weight of the sub-active component accounts for 0-5% of the total weight of the active component, the sub-active component and the non-active component; the particle size of the sub-active component ranges from 5nm to 5μm. The oxygen carrier for chemical looping hydrogen production according to claim 1, characterized in that, the stabilized zirconia comprises one or more of magnesium stabilized zirconia, yttrium stabilized zirconia, calcium stabilized zirconia and cerium stabilized zirconia. The oxygen carrier for chemical looping hydrogen production according to claim 1, characterized in that, the active component is NiO, and the non-active component comprises one or more of ZrO2, MgAl2O4 and CaAl2O4. The oxygen carrier for chemical looping hydrogen production according to claim 4, characterized in that, the active component is NiO, and the non-active component comprises ZrO2; the weight of NiO accounts for 10-25% of the total weight of NiO and ZrO2, and the weight of ZrO2 accounts for 75-90% of the total weight of NiO and ZrO2. The oxygen carrier for chemical looping hydrogen production according to claim 5, characterized in that, the particle size of NiO is 500nm, and the particle size of ZrO2 is 500nm. The oxygen carrier for chemical looping hydrogen production according to claim 1, characterized in that, the particle size of the active component ranges from 5nm to 500nm, and the particle size of the non-active component ranges from 5nm to 500nm. The oxygen carrier for chemical looping hydrogen production according to claim 2, characterized in that, the particle size of the sub-active component ranges from 5nm to 500nm. A preparation method of an oxygen carrier for chemical looping hydrogen production, characterized by comprising the following steps: A preparation method for the oxygen carrier for chemical looping hydrogen production according to claim 2, comprising the following steps: S10, mixing the active component, the sub-active component and the non-active component in proportion to obtain a mixture powder; S20, granulating and shaping the powder; S30, placing the granulated and shaped particles into a heating furnace for heat treatment, and after the heat treatment is completed, cooling to obtain the final oxygen carrier. The preparation method according to claim 9, characterized in that, The step S10 and the step S20 further comprise a step S15 of putting the obtained mixture powder into a heating furnace for heat treatment, and after the heat treatment, the first powder is obtained after cooling. The preparation method according to claim 9, wherein, In the step S10, the weight of the active component accounts for 10-25% of the total weight of the active component, the sub-active component and the non-active component; the weight of the sub-active component accounts for 0-5% of the total weight of the active component, the sub-active component and the non-active component; and the weight of the non-active component accounts for 75-90% of the total weight of the active component, the sub-active component and the non-active component. The preparation method according to claim 10, wherein, In the step S15, the mixture powder is subjected to heat treatment in the heating furnace, and the temperature rising process adopts programmed temperature rising, the temperature rising speed is 10-35 ℃ / min, and after the temperature reaches the set temperature, the temperature is maintained for 5-15 h. The set temperature is a specific temperature in the range of 900-1250 ℃. The preparation method according to claim 12, wherein, In the step S20, the granulation is performed by mechanical granulation, and the obtained granules have a kinetic equivalent diameter of 2-9 mm. The preparation method according to claim 13, wherein, In the step S30, the granules after the granulation are subjected to heat treatment in the heating furnace, and the temperature rising process adopts programmed temperature rising, the temperature rising speed is 10-35 ℃ / min, and after the temperature reaches the set temperature, the temperature is maintained for 5-15 h. The set temperature is a specific temperature in the range of 850-1350 ℃. A multi-stage coupled chemical looping hydrogen production method, characterized in that, The method uses a multi-stage coupled chemical looping hydrogen production device, which comprises: The multi-stage coupled chemical looping hydrogen production device comprises a first-stage chemical looping reaction unit and a second-stage chemical looping reaction unit, The first-stage chemical looping reaction unit comprises a first-stage reducer and a water vapor oxidation hydrogen generator, and the two parts can be converted to each other and repeated as a whole according to the reaction stage; The second-stage chemical looping reaction unit comprises a second-stage reducer, a methane reformer and an air oxidizer, and the three parts can be converted to each other and repeated as a whole according to the reaction stage; The same first oxygen carrier is arranged in the first-stage reducer and the water vapor oxidation hydrogen generator, the first oxygen carrier changes into a metal element or a metal oxide with different chemical valences in each reaction stage, and the metal has multiple valences; The same second oxygen carrier is arranged in the second-stage reducer, the methane reformer and the air oxidizer, the second oxygen carrier changes into a metal element or a metal oxide with different chemical valences in each reaction stage, and the metal element corresponding to the second oxygen carrier acts as a catalyst in the methane reforming reaction in the methane reformer; The methane reformer is connected with the first-stage reducer, and is used for delivering the synthesis gas after the methane reforming to the first-stage reducer; The second-stage reducer is connected with the methane reformer, and is used for returning carbon dioxide or water vapor or both to the methane reformer. The first-stage reducer is connected with the second-stage reducer, and is configured to deliver a reduction tail gas containing carbon monoxide or hydrogen or both to the second-stage reducer; The multi-stage coupled chemical looping hydrogen production method comprises the following steps: Device start-up and oxygen carrier and reactor preparation step, in which the multi-stage coupled chemical looping hydrogen production device is started up, and the first oxygen carriers are respectively filled into the two reactors corresponding to the first-stage chemical looping reaction unit, and the second oxygen carriers are respectively filled into the three reactors corresponding to the second-stage chemical looping reaction unit; Reactor pretreatment step, in which the above-mentioned total of five reactors are respectively heated, and the system as a whole is adjusted to be suitable for the following reactions by means of pre-reduction and pre-oxidation cooperation, i.e., the first-stage reduction reaction and the water vapor oxidation hydrogen production reaction are repeatedly performed in a mutual switching mode between the two reactors corresponding to the first-stage chemical looping reaction unit, and the second-stage reduction reaction, the methane conversion reaction and the air oxidation reaction are repeatedly performed in a mutual switching mode between the three reactors corresponding to the second-stage chemical looping reaction unit; Methane conversion step, in which a methane-containing combustible gas is introduced into the methane converter, which is first mixed with the reduction tail gas circulated from the second-stage reducer, then the methane and the mixed gas containing CO2 or H2O or both undergo the methane conversion reaction under the catalysis of the elemental metal, and the heat accumulated in the oxygen carrier in the air oxidation step is fully utilized to generate synthesis gas containing CO, H2, CO2 and H2O components, which enters the first-stage reducer of the first-stage chemical looping reaction unit; Air oxidation step, after the methane conversion reaction is completed, the reactor is switched to the state of the air oxidizer and the air oxidation process is performed, i.e., air or oxygen is introduced into the air oxidizer to oxidize the elemental metal oxygen carrier to a high-valence state, and a large amount of reaction heat is released, most of which is accumulated in the oxidized oxygen carrier bed to store heat in advance for the required reaction heat of the subsequent methane conversion process; Second-stage reduction step, after the air oxidation is completed, the reactor is switched to the state of the second-stage reducer and the second-stage reduction process is performed, i.e., the residual CO and H2 in the first-stage reduction tail gas reduce the second oxygen carrier in the second-stage reducer from a high-valence oxide state to an elemental state, while the CO and H2 are completely oxidized to CO2 and H2O, and the second-stage reduction process is ensured not to penetrate by controlling and adjusting the switching time, so that the second-stage reduction tail gas is all CO2 and H2O, and a part of the tail gas is returned to the methane converter to mix with the methane-containing fuel gas and then perform the methane conversion reaction, and the remaining part is cooled to condense H2O to obtain high-purity CO2 and perform CO2 capture after recovering heat; The first-stage reduction step is to introduce the synthesis gas containing CO and H2 generated by the methane reformer into the first-stage reducer to reduce the sub-high-valence metal oxide state of the oxygen carrier to a low-valence metal oxide or metal element by CO and H2 in the synthesis gas, and to partially oxidize the synthesis gas by the first-stage chemical looping oxygen carrier to generate a mixed gas containing unreacted residual CO, H2, CO2 and H2O, i.e. the first-stage reduction tail gas, which is returned to the second-stage reducer of the second-stage chemical looping reaction unit; The water vapor oxidation hydrogen production step is to introduce water vapor into the water vapor oxidation hydrogen production device to oxidize the low-valence metal oxide oxygen carrier or metal element generated in the first-stage reduction step to a sub-high-valence oxidation state, while generating high-purity hydrogen gas; The multi-stage coupled chemical looping hydrogen production device comprises a first-stage chemical looping reaction unit and a second-stage chemical looping reaction unit, The first-stage chemical looping reaction unit comprises a first-stage reducer and a water vapor oxidation hydrogen production device, which can be converted to each other and cyclically repeated as a whole according to the reaction stage; The second-stage chemical looping reaction unit comprises a second-stage reducer, a methane reformer and an air oxidizer, which can be converted to each other and cyclically repeated as a whole according to the reaction stage; The same oxygen carrier is arranged in the first-stage reducer and the water vapor oxidation hydrogen production device, which changes to a metal element or a metal oxide of different chemical valence in each reaction stage, and the metal has multiple valences; The same second oxygen carrier is arranged in the second-stage reducer, the methane reformer and the air oxidizer, which changes to a metal element or a metal oxide of different chemical valence in each reaction stage, and the metal element of the second oxygen carrier acts as a catalyst in the methane reforming reaction in the methane reformer; The methane reformer is connected with the first-stage reducer to deliver the synthesis gas after methane reforming to the first-stage reducer; The second-stage reducer is connected with the methane reformer to return carbon dioxide or water vapor or both to the methane reformer; The first-stage reducer is connected with the second-stage reducer to deliver the reduction tail gas containing carbon monoxide or hydrogen or both to the second-stage reducer; The second oxygen carrier comprises an active component and an inactive component, the active component comprises one or more of NiO, CuO and ZnO, and the inactive component comprises one or more of ZrO2, MgO, Y2O3, stabilized zirconia, MgAl2O4, CaAl2O4, CaO, Al2O3 and TiO2, The weight of the active component accounts for 10-25% of the total weight of the active component and the inactive component, and the weight of the inactive component accounts for 75-90% of the total weight of the active component and the inactive component; The particle size of the active component ranges from 5 nm to 5 μm, and the particle size of the inactive component ranges from 5 nm to 5 μm. The oxygen carrier for chemical looping hydrogen production according to claim 15, wherein The stable zirconia includes one or more of magnesium-stabilized zirconia, yttrium-stabilized zirconia, calcium-stabilized zirconia and cerium-stabilized zirconia. The multi-stage coupled chemical looping hydrogen production method according to claim 15, characterized in that, The second oxygen carrier further comprises a sub-active component, and the sub-active component is one or more of Fe2O3, CeO2, Co3O4 and Mn2O3. The weight of the sub-active component accounts for 0-5% of the total weight of the active component, the sub-active component and the non-active component. The particle size of the sub-active component ranges from 5 nm to 5 μm.

Images