Oxygen carrier for chemical looping hydrogen production, 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 used in a multi-stage coupled chemical looping hydrogen production apparatus, comprising an active component and an inactive component. The active component comprises Fe2O3 or Fe3O4, and the inactive component comprises one or more of Al2O3, MgO, ZrO2, Y2O3, stabilized zirconia, MgAl2O4, CaAl2O4, TiO2, and CaO, wherein the weight of the active component accounts for 50%-95% of the total weight of the active component and the inactive component; the weight of the inactive component accounts for 5%-50% of the total weight of the active component, a secondary 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 low manufacturing cost, does not generate pollutants in the preparation process, and thus can be widely used in chemical looping hydrogen production. Moreover, the oxygen carrier has good weight recovery and a high average weight loss degree during repeated reactions.

Description

Oxygen carrier for chemical looping hydrogen production, preparation method thereof, and multistage coupled chemical looping hydrogen production method TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical looping hydrogen production, and in particular to an oxygen carrier for chemical looping hydrogen production, a preparation method thereof, and a multistage coupled chemical looping hydrogen production method. BACKGROUND

[0002] Chemical looping hydrogen production technology is a method for producing hydrogen gas by using chemical looping technology. It combines fuel with an oxygen carrier through a specific reaction process, thereby achieving efficient utilization of fuel and capture of CO2. Chemical looping hydrogen production technology has the characteristics of high efficiency, cleanliness and economy, and the preparation and selection of the oxygen carrier are the key to realizing chemical looping technology. The oxygen carrier plays a role in transferring oxygen and heat in the chemical looping hydrogen production technology, and therefore the performance of the oxygen carrier directly affects the operation of the entire chemical looping hydrogen production system, which requires the oxygen carrier to have high reaction activity and high multi-cycle stability. The formula composition, preparation method and parameters of the oxygen carrier are the two most important factors affecting the final performance of the oxygen carrier.

[0003] The Chinese invention patent with application number 202410022173.7 submitted by the applicant discloses a brand-new multistage coupled chemical looping hydrogen production device and method, which has the greatest feature of containing two chemical looping cycle units: a first chemical looping reaction unit and a second chemical looping reaction unit. The oxygen carrier for the two chemical looping reaction units is disclosed, i.e., a first oxygen carrier (corresponding to the first chemical looping reaction, a water vapor oxidation-reduction process) and a second oxygen carrier (corresponding to the second chemical looping reaction, a first-stage reduction tail gas reduction oxidation process).

[0004] The above-mentioned invention patent also discloses that the first oxygen carrier contains active ingredients such as Fe3O4, and optionally contains sub-active ingredients (one or more of MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2) or non-active ingredients (one or more of Al2O3, ZrO2, Y2O3, MgAl2O4, CaAl2O4, TiO2, CaO) or both; and the second oxygen carrier contains active ingredients (one or more of NiO, CuO, ZnO), and optionally contains sub-active ingredients (one or more of Fe2O3, CeO2, Co3O4, Mn2O3) or non-active ingredients (one or more of ZrO2, MgO, Y2O3, MgAl2O4, CaAl2O4, CaO, Al2O3, TiO2) or both.

[0005] In addition, the preparation method of the first oxygen carrier with high redox activity, good sintering resistance and redox cycle stability is sol-gel method or coprecipitation method. The method is obtained by mixing the active component salt solution (usually iron) with the secondary active component or non-active component salt solution, adding other acid or base solution to mix and precipitate, and then high-temperature calcining to obtain a composite metal oxide oxygen carrier containing active component, secondary active component and non-active component. However, the production process is complex, and a large amount of pollutants will be generated during high-temperature calcination of the solid metal salt obtained by sol-gel method, resulting in high cost of the oxygen carrier preparation, thereby affecting its popularization and application in the process of chemical chain hydrogen production. SUMMARY

[0006] Therefore, the inventors further studied on the basis of the above-mentioned Chinese invention application with application number 202410022173.7, and found a more preferred range and component combination of the first oxygen carrier through examples and experimental results. Meanwhile, in the process of manufacturing the first oxygen carrier, a preferred manufacturing process was found, and the present application was further completed.

[0007] The present application aims to provide a chemical chain hydrogen production oxygen carrier (first oxygen carrier) capable of maintaining high reaction activity and high cycle stability, a manufacturing method thereof, and a multi-stage coupled chemical chain hydrogen production method using the oxygen carrier.

[0008] To achieve the above-mentioned purpose, the technical solution of the present application is: a chemical chain hydrogen production oxygen carrier for a multi-stage coupled chemical chain hydrogen production device,

[0009] which comprises an active component and a non-active component, the active component comprises Fe2O3 or Fe3O4, and the non-active component comprises one or more of Al2O3, MgO, ZrO2, Y2O3, stabilized zirconia, MgAl2O4, CaAl2O4, TiO2 and CaO,

[0010] wherein the weight of the active component accounts for 50-95% of the total weight of the active component and the non-active component; the weight of the non-active component accounts for 5-50% of the total weight of the active component, the secondary active component and the non-active component; the particle size of the active component ranges from 5nm to 5um, and the particle size of the non-active component ranges from 5nm to 5um.

[0011] Further, the oxygen carrier further comprises a secondary active component, the secondary active component comprises one or more of MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2 and CoO; wherein 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 non-active component; the particle size of the secondary active component ranges from 5nm to 5um.

[0012] Further, the stable zirconia includes one or more of magnesium-stabilized zirconia, yttrium-stabilized zirconia, calcium-stabilized zirconia and cerium-stabilized zirconia.

[0013] Further, the active component is Fe2O3, and the inactive component includes one or more of ZrO2, Y2O3 and Al2O3.

[0014] Further, the active component is Fe2O3, the inactive component includes ZrO2 and Y2O3; the weight of Fe2O3 accounts for 50-95% of the total weight of Fe2O3, ZrO2 and Y2O3, and the weight of ZrO2 and Y2O3 accounts for 5-50% of the total weight of Fe2O3, ZrO2 and Y2O3.

[0015] Further, the particle size of Fe2O3 is 1 μm, the particle size of ZrO2 is 500 nm, and the particle size of Y2O3 is 50 nm.

[0016] Further, the particle size of the active component ranges from 20 nm to 2 μm, and the particle size of the inactive component ranges from 5 nm to 2 μm.

[0017] Further, the particle size of the sub-active component ranges from 5 nm to 2 μm.

[0018] The present application also provides a preparation method of the oxygen carrier as follows:

[0019] The preparation method includes the following steps:

[0020] S10, mixing the active component, the sub-active component and the inactive component in proportion to obtain a mixture powder;

[0021] S20, granulating and forming the powder;

[0022] S30, putting the granulated and formed particles into a heating furnace for heat treatment, and obtaining the final oxygen carrier after cooling after the heat treatment.

[0023] Further, between step S10 and step S20, there is also step S15: putting the obtained mixture powder into a heating furnace for heat treatment, and obtaining a first powder after cooling after the heat treatment.

[0024] Further, in step S10, the weight of the active component accounts for 50-95% of the total weight of the active component, the sub-active component and the inactive 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 inactive component, and the weight of the inactive component accounts for 5-50% of the total weight of the active component, the sub-active component and the inactive component.

[0025] Further, in step S15, the mixture powder is heat treated in a heating furnace, and a programmed temperature rising is adopted in the temperature rising process, with a temperature rising rate of 10-35 DEG C / min, and after the temperature reaches a set temperature, it is maintained for 5-15 h; wherein the set temperature is a certain specific temperature within the range of 800-1300 DEG C.

[0026] Further, in step S20, a mechanical granulation method is adopted to form granules, and the kinetic equivalent diameter of the obtained granules is 1-9 mm.

[0027] Further, in step S30, the granules after granulation are heat treated in a heating furnace, and a programmed temperature rising is adopted in the temperature rising process, with a temperature rising rate of 10-35 DEG C / min, and after the temperature reaches a set temperature, it is maintained for 5-15 h; wherein the set temperature is a certain specific temperature within the range of 800-1300 DEG C.

[0028] The application further provides a multi-stage coupled chemical chain hydrogen production method.

[0029] The multi-stage coupled chemical chain hydrogen production method uses a multi-stage coupled chemical chain hydrogen production device, which is as follows:

[0030] The multi-stage coupled chemical chain hydrogen production device comprises a first-stage chemical chain reaction unit and a second-stage chemical chain reaction unit,

[0031] The first-stage chemical chain 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 cyclically repeated as a whole according to the reaction stage;

[0032] The second-stage chemical chain 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 cyclically repeated as a whole according to the reaction stage;

[0033] 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;

[0034] 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;

[0035] The methane reformer is connected with the first-stage reducer, and is used to deliver the synthesis gas after methane reforming to the first-stage reducer;

[0036] The second section reducer is connected with the methane converter for returning carbon dioxide or steam or both to the methane converter;

[0037] The first section reducer is connected with the second section reducer for feeding the second section reducer with the reduction tail gas containing carbon monoxide or hydrogen or both;

[0038] The multi-stage coupled chemical looping hydrogen production method comprises the following steps:

[0039] Device starting and carrier and reactor preparation steps, in which the multi-stage coupled chemical looping hydrogen production device is started, and the first carrier is filled into the two reactors corresponding to the first section chemical looping reaction unit respectively, and the second carrier is filled into the three reactors corresponding to the second section chemical looping reaction unit respectively;

[0040] Reactor pretreatment steps, in which the above-mentioned total 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 section reduction reaction and the steam oxidation hydrogen production reaction are repeatedly performed in the two reactors corresponding to the first section chemical looping reaction unit by mutual switching, and the second section reduction reaction, the methane conversion reaction and the air oxidation reaction are repeatedly performed in the three reactors corresponding to the second section chemical looping reaction unit by mutual switching;

[0041] Methane conversion steps, in which the methane combustible gas is introduced into the methane converter, which is first mixed with the reduction tail gas circulated from the second section reducer, then the methane is subjected to the methane conversion reaction under the catalysis of the elemental metal, and the heat accumulated in the carrier in the air oxidation step is fully utilized, to generate the synthesis gas containing CO, H2, CO2 and H2O components, which enters the first section reducer of the first section chemical looping reaction unit;

[0042] Air oxidation steps, 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 carrier in the elemental metal state to the high-valence state, and a large amount of reaction heat is released, most of which is accumulated in the carrier bed layer after oxidation, to store heat in advance for the reaction heat required in the subsequent methane conversion process;

[0043] 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, that is, the remaining CO and H2 in the first-stage reduction tail gas reduce the second-stage reducer from the high-valence oxide state to the elemental state, while the CO and H2 are completely oxidized to CO2 and H2O, and the switching time is adjusted by control to ensure that the second-stage reduction process does not penetrate, 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 reformer to mix with the methane-containing fuel gas and then perform the methane reforming reaction, and the remaining part is recovered after the heat is condensed to obtain high-purity CO2 and perform CO2 capture;

[0044] 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, so that the sub-high-valence metal oxide state of the oxygen carrier is reduced to a low-valence metal oxide or metal element by CO and H2 in the synthesis gas, and the synthesis gas is partially oxidized by the first-stage chemical looping oxygen carrier to generate a mixed gas containing unreacted remaining CO, H2, CO2 and H2O, i.e. first-stage reduction tail gas, which is returned to the second-stage reducer of the second-stage chemical looping reaction unit;

[0045] 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 oxide state, while generating high-purity hydrogen gas;

[0046] The multi-stage coupled chemical looping hydrogen production device includes a first-stage chemical looping reaction unit and a second-stage chemical looping reaction unit,

[0047] The first-stage chemical looping reaction unit includes a first-stage reducer and a water vapor oxidation hydrogen production device, and the two parts can be converted to each other and repeatedly circulated as a whole according to the reaction stage;

[0048] The second-stage chemical looping reaction unit includes a second-stage reducer, a methane reformer and an air oxidizer, and the three parts can be converted to each other and repeatedly circulated as a whole according to the reaction stage;

[0049] The same oxygen carrier is arranged in the first-stage reducer and the water vapor oxidation hydrogen production device, the oxygen carrier changes to a metal element or a metal oxide of different chemical valence in each reaction stage, and the metal has multiple valences;

[0050] The same second-stage oxygen carrier is arranged in the second-stage reducer, the methane reformer and the air oxidizer, the second-stage oxygen carrier changes to a metal element or a metal oxide of different chemical valence in each reaction stage, and the metal element corresponding to the second-stage oxygen carrier acts as a catalyst in the methane reforming reaction in the methane reformer;

[0051] The methane converter is connected with the first-stage reducer for conveying the converted syngas to the first-stage reducer;

[0052] The second-stage reducer is connected with the methane converter for returning carbon dioxide or steam or both to the methane converter;

[0053] The first-stage reducer is connected with the second-stage reducer for conveying the reduction tail gas containing carbon monoxide or hydrogen or both to the second-stage reducer;

[0054] The active component includes Fe2O3 or Fe3O4, and the inactive component includes one or more of Al2O3, MgO, ZrO2, Y2O3, stabilized zirconia, MgAl2O4, CaAl2O4, TiO2 and CaO,

[0055] The weight of the active component accounts for 50-95% of the total weight of the active component and the inactive component, and the weight of the inactive component accounts for 5-50% of the total weight of the active component, the sub-active component and the inactive component;

[0056] 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.

[0057] Further, the stabilized zirconia includes one or more of magnesium-stabilized zirconia, yttrium-stabilized zirconia, calcium-stabilized zirconia and cerium-stabilized zirconia.

[0058] Further, the first oxygen carrier further includes a sub-active component, and the sub-active component is one or more of MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2 and CoO; 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 inactive component; and the particle size of the sub-active component ranges from 5 nm to 5 μm.

[0059] Therefore, the application provides a preferred combination of components and chemical components of the first oxygen carrier, and provides a preparation method of the first oxygen carrier which is low in manufacturing cost, does not produce pollutants in the preparation process, can be widely applied in the chemical chain hydrogen production, and has good weight recovery, high average weight loss degree and the like in repeated reactions, and a multi-stage coupled chemical chain hydrogen production method using the first oxygen carrier. BRIEF DESCRIPTION OF DRAWINGS

[0060] Fig. 1 is a flow chart of the preparation method of the oxygen carrier for chemical chain hydrogen production in the application.

[0061] Fig. 2 is a graph of the results of the redox thermogravimetric experiment of the first oxygen carrier A in the application.

[0062] Figure 3 is a graph of the results of the redox thermogravimetric experiment of the first oxygen carrier B of the present application.

[0063] Figure 4 is a graph of the results of the redox thermogravimetric experiment of the first oxygen carrier C of the present application.

[0064] Figure 5 is a structural schematic diagram of the multi-stage coupled chemical looping hydrogen production device of the present application. DETAILED DESCRIPTION

[0065] The technical solutions of the present application are further described below in combination with the embodiments and the accompanying drawings. First, the multi-stage coupled chemical looping hydrogen production device and method using the first oxygen carrier of the present application are described with reference to Figure 5, second, the manufacturing process of the first oxygen carrier of the present application is described with reference to Figure 1, and finally, the preferred first oxygen carrier of the present application and the manufacturing method thereof are described with reference to Figures 2, 3, and 4.

[0066] (Description of the multi-stage coupled chemical looping hydrogen production device and method of the present application)

[0067] Figure 5 is a structural schematic diagram of the multi-stage coupled chemical looping hydrogen production device of the embodiment of the present application. As shown in Figure 5, the multi-stage coupled chemical looping hydrogen production device of the present application includes a first-stage chemical looping reaction unit represented by the upper box in the figure and a second-stage chemical looping reaction unit represented by the lower box.

[0068] The first-stage chemical looping reaction unit includes a first-stage reducer and a water vapor oxidation hydrogen generator, which can be converted to each other according to the reaction stage.

[0069] A metal oxide (represented by metal N) is provided in both the first-stage reducer and the water vapor oxidation hydrogen generator as an oxygen carrier (hereinafter referred to as "first oxygen carrier") in the reduction-oxidation reaction. The metal N must be selected from a metal having multiple valence states, and the initial state of the first oxygen carrier can be an oxide of the metal N, for example, a sub-high valence metal oxide, and further, in the case of N being Fe, it can be Fe3O4. However, the initial state thereof can be an oxide state of a metal having other valence, for example, in the case of N being Fe, the initial state of the first oxygen carrier can be Fe2O3.

[0070] The first oxygen carrier includes an active component, a non-active component, and optionally a sub-active component. The active component includes Fe2O3 or Fe3O4; the sub-active component includes one or more of MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2, and CoO, but is not limited thereto; and the non-active component includes one or more of Al2O3, MgO, ZrO2, Y2O3, stabilized zirconia (including one or more of magnesium-stabilized zirconia, yttrium-stabilized zirconia, calcium-stabilized zirconia, and cerium-stabilized zirconia), MgAl2O4, CaAl2O4, TiO2, and CaO. Here, the main role of the active component is to act as an oxygen carrier in the redox cycle, especially to obtain pure hydrogen in the steam oxidation process; the main role of the sub-active component is to improve and stabilize the performance of the active component; and the main role of the non-active component is to make the properties of the oxygen carrier more stable, avoid sintering, and build a stable pore structure.

[0071] The first-stage reducer and the steam oxidation hydrogen generator use multiple pipelines and valves arranged on the pipelines to switch the functions of the two reaction units. For example, when two reactors corresponding to the first-stage reducer and the steam oxidation hydrogen generator are defined as reactor D and reactor E, initially, reactor D implements the function of the first-stage reducer and reactor E implements the function of the steam oxidation hydrogen generator, but after switching the pipelines through the valves, reactor D implements the function of the steam oxidation hydrogen generator and reactor E implements the function of the first-stage reducer.

[0072] Next, the multi-stage coupled chemical looping hydrogen production method using the multi-stage coupled chemical looping hydrogen production device of the present application is described.

[0073] As shown in FIG. 5, when using the multi-stage coupled chemical looping hydrogen production device of the present application to perform the hydrogen production process, first, the device is started and the oxygen carriers and the reactors are prepared. Specifically, in the five reactors (A / B / C / D / E) in the multi-stage coupled chemical looping hydrogen production device, the two reactors D and E corresponding to the first-stage chemical looping reaction unit are filled with the first oxygen carrier described above, and the reactors A / B / C corresponding to the second-stage chemical looping reaction unit are filled with the second oxygen carrier. Here, the initial oxygen carriers can have an oxidation state of the active component metal that is the working state in the actual redox cycle or another state (adjusted to the working state through the first redox cycle after actual work). For example, although the active component in the first oxygen carrier is Fe3O4 after the cycle starts, Fe2O3 can be used in the initial oxygen carrier.

[0074] Next, all five reactors (A / B / C / D / E) are heated to a specified temperature.

[0075] After the 3 reactors (A / B / C) of the second stage chemical looping unit are prepared for the pre-reduction of the oxygen carrier, H2 is introduced into the 3 reactors (A / B / C) to start the pre-reduction of the oxygen carrier. When all the reactors complete the pre-reduction, one of the reactors A is introduced with air to perform air oxidation and heat accumulation. When the reactor A that completes the air oxidation and heat accumulation is switched to H2 reduction, and continues to accumulate heat; at the same time, another reactor B performs air oxidation.

[0076] The reactor A that completes the hydrogen reduction and heat accumulation starts to introduce CH4-containing combustible gas to perform methane conversion and produce synthesis gas containing CO and H2; at the same time, the reactor B is switched to oxygen carrier reduction, and the reduction gas comes from the reduction tail gas (containing penetrated CO and H2) of the first stage chemical looping unit; at the same time, the reactor C performs air oxidation.

[0077] The reactor A that completes the methane conversion is switched to the air oxidation process to perform air oxidation and heat production and accumulation; the reactor B is switched to the methane conversion process; and the reactor C is switched to the oxygen carrier reduction process.

[0078] After the reactor A completes the air oxidation, it is switched to the oxygen carrier reduction process; after the reactor B completes the methane conversion, it is switched to the air oxidation process; and the reactor C is switched to the methane conversion process at this time.

[0079] The subsequent process of the second stage chemical looping unit is cycled and switched in the 3 reactors (A / B / C).

[0080] On the other hand, the synthesis gas enters the reactor D of the 2 reactors (D / E) of the first stage chemical looping unit to reduce the first oxygen carrier arranged therein, and the reduction tail gas (containing penetrated CO and H2) returns to the reactor (second stage reducer) of the second stage chemical looping unit in a reduction state to reduce the second oxygen carrier therein.

[0081] The reactor D that completes the reduction of the first oxygen carrier is switched to the steam oxidation hydrogen production process to perform the steam oxidation hydrogen production reaction, and at the same time, the reactor E is introduced with synthesis gas to perform the first oxygen carrier reduction reaction. Next, the reactor D that completes the oxygen carrier steam oxidation hydrogen production is switched to the oxygen carrier reduction, and the reactor E that completes the reduction is switched to the steam oxidation hydrogen production, and the above-mentioned cycle process is repeated.

[0082] (Explanation of the first oxygen carrier for chemical looping hydrogen production and the preparation method thereof)

[0083] Figure 1 is a flow chart of the preparation method of the oxygen carrier for chemical looping hydrogen production in the present application. As shown in Figure 1, the present application proposes an oxygen carrier material for a chemical looping hydrogen production process and a large-scale preparation method. The oxygen carrier is used in the first-stage chemical looping reaction unit mentioned in the above patent application 202410022173.7, and can also be used in the two-cycle process of "oxygen carrier reduction-oxygen carrier water vapor oxidation hydrogen production" or the three-cycle process of "oxygen carrier reduction-water vapor oxidation hydrogen production-oxygen carrier air oxidation" of other independent chemical looping hydrogen production processes.

[0084] The first oxygen carrier composition can be as follows, but is not limited thereto:

[0085] The active component is Fe2O3 or Fe3O4;

[0086] Optionally containing a secondary active component: one or more of MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2 and CoO;

[0087] Containing a non-active component: one or more of Al2O3, MgO, ZrO2, Y2O3, stabilized zirconia (including one or more of magnesium stabilized zirconia, yttrium stabilized zirconia, calcium stabilized zirconia and cerium stabilized zirconia), MgO, MgAl2O4, CaAl2O4, TiO2 and CaO;

[0088] Wherein, the weight of the active component accounts for 50-95% of the total weight of the active component and the non-active component; the weight of the non-active component accounts for 5-50% of the total weight of the active component, the secondary active component and the non-active 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 non-active component;

[0089] The particle size of the active component ranges from 5 nm to 5 μm, the particle size of the non-active component ranges from 5 nm to 5 μm, and the particle size of the secondary active component ranges from 5 nm to 5 μm.

[0090] The first oxygen carrier can be prepared by the following method, but is not limited thereto:

[0091] (1) Mix the active component, without the secondary active component or optionally containing one or more of the secondary active component, and one or more of the non-active component in a certain proportion to obtain a mixture powder.

[0092] (2) Optionally, put the obtained mixture powder into a heating furnace for heat treatment. The heating process adopts programmed heating with a rate of 10-35 ℃ / min. After reaching a specified temperature (a certain specific temperature within the range of 800-1300 ℃), maintain for 5-15 h, and cool to obtain the first powder.

[0093] (3) The mixture powder or the first powder is granulated to form a granule with a kinetic equivalent diameter of 1 mm to 9 mm.

[0094] (4) The granule after granulation is put into a heating furnace for heat treatment. The heating process uses programmed heating with a rate of 10 to 35 °C / min. After reaching a specified temperature (a certain specific temperature in the range of 900 to 1300 °C), the temperature is maintained for 5 to 15 h. After cooling, the final oxygen carrier is obtained.

[0095] Next, the first oxygen carrier of the present application is described in detail.

[0096] (Example 1: Preparation of the first oxygen carrier A)

[0097] The first oxygen carrier A is manufactured by the following method.

[0098] (1) Fe2O3 with a particle size of 1 μm and Al2O3 powder with a particle size of 500 nm are respectively put into a drying oven and dried at 105 °C until constant weight. 400 g and 100 g of the dried powders are respectively weighed and mixed to obtain a mixture powder.

[0099] (2) The obtained mixture powder is put into a heating furnace and heated to 950 °C at a rate of 15 °C / min. The temperature is maintained for 6 h. After cooling, a first powder is obtained.

[0100] (3) The first powder is mechanically granulated to form a spherical granule with a diameter of 4 mm.

[0101] (4) The granule after granulation is put into a heating furnace and heated to 950 °C at a rate of 15 °C / min. The temperature is maintained for 6 h. After cooling, the final oxygen carrier is obtained.

[0102] Figure 2 shows the continuous test results of the weight loss rate of the first oxygen carrier A in the repeated oxidation-reduction process. As shown in Figure 2, the weight change of the first oxygen carrier A in the repeated oxidation-reduction process has good repeatability, and the average maximum weight loss rate of each cycle is measured to be 19.5%.

[0103] (Example 2: Preparation of the first oxygen carrier B)

[0104] The first oxygen carrier B is manufactured by the following method.

[0105] (1) Fe2O3 with a particle size of 1 μm and ZrO2 powder with a particle size of 500 nm are respectively put into a drying oven and dried at 105 °C until constant weight. 550 g and 450 g of the dried powders are respectively weighed and mixed to obtain a mixture powder.

[0106] (2) The mixture powder obtained is put into a heating furnace, and heated to 950°C at a temperature increasing rate of 15°C / min, maintained for 9 hours, and cooled to obtain a first powder.

[0107] (3) The first powder is mechanically granulated and molded to obtain spherical particles with a diameter of 4 mm.

[0108] (4) The oxygen carrier after granulation and molding is put into a heating furnace, and heated to 1100°C at a temperature increasing rate of 15°C / min, maintained for 9 hours, and cooled to obtain a final oxygen carrier.

[0109] Fig. 3 shows the results of continuous testing of the weight loss rate of the first oxygen carrier B in repeated redox processes. As shown in Fig. 3, the first oxygen carrier B has good repeatability in weight change in repeated redox processes, and the average of the maximum weight loss rate of each cycle is measured to be 15.5%.

[0110] (Example 3: Preparation of a first oxygen carrier C)

[0111] The first oxygen carrier C is manufactured by the following method.

[0112] (1) Fe2O3 powder with a particle size of 1 μm, ZrO2 powder with a particle size of 500 nm, and Y2O3 powder with a particle size of 50 nm are respectively put into a drying oven and dried at 105°C until constant weight, and the dried powders are weighed to be 800 g, 173 g, and 27.5 g, respectively, and mixed to obtain a mixture powder.

[0113] (2) The mixture powder obtained is put into a heating furnace, and heated to 950°C at a temperature increasing rate of 15°C / min, maintained for 6 hours, and cooled to obtain a first powder.

[0114] (3) The first powder is granulated and molded to obtain columnar particles with a size of φ4 mm x H 8 mm (kinetic equivalent diameter of 5.02 mm).

[0115] (4) The particles after granulation and molding are put into a heating furnace, and heated to 950°C at a temperature increasing rate of 15°C / min, maintained for 6 hours, and cooled to obtain a final oxygen carrier.

[0116] Fig. 4 shows the results of continuous testing of the weight loss rate of the first oxygen carrier C in repeated redox processes. As shown in Fig. 4, the first oxygen carrier C has good repeatability in weight change in repeated redox processes, and the average of the maximum weight loss rate of each cycle is measured to be 23.2%.

[0117] (Results and analysis of Examples 1-3)

[0118] The following table summarizes the specific data of the active components and the inactive components of Examples 1-3 above, and the average of the maximum weight loss rate of each cycle.

[0119] From the above table, it can be seen that the weight change repeatability of the first oxygen carriers of embodiments 1-3 of the present application is good when repeatedly performing the redox reaction, and, in terms of the size of the average value of the maximum weight loss rate of each cycle, embodiment 3 is the largest, which indicates that the first oxygen carrier C of embodiment 3 is the most active in the redox process, and is the preferred embodiment.

[0120] (Examples 4, 5, 6: Preparation of first oxygen carriers D, E, F)

[0121] The first oxygen carriers D, E, F were prepared by the methods of Examples 4, 5, 6 of the present application, and the weight change repeatability when repeatedly reacting, and the average value of the maximum weight loss rate of each cycle were as follows, respectively:

[0122] The above examples are only used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent substitutions for part of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An oxygen carrier for chemical loop hydrogen production in a multi-stage coupled chemical loop hydrogen production device, characterized in that, It includes active and inactive components. The active component includes Fe2O3 or Fe3O4, and the inactive component includes one or more of Al2O3, MgO, ZrO2, Y2O3, stabilized zirconium oxide, MgAl2O4, CaAl2O4, TiO2, and CaO. The active component accounts for 50-95% of the total weight of the active and inactive components; the inactive component accounts for 5-50% of the total weight of the active, secondary, and inactive components. 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.

2. The oxygen carrier for chemically looped hydrogen production according to claim 1, characterized in that, It also includes secondary active components, which include one or more of MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2, and CoO. 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. The particle size range of the secondary active ingredient is 5 nm to 5 μm.

3. The oxygen carrier for chemically looped hydrogen production according to claim 1, characterized in that, 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.

4. The oxygen carrier for chemically looped hydrogen production according to claim 1, characterized in that, The active component is Fe2O3, and the inactive component includes one or more of ZrO2, Y2O3 and Al2O3.

5. The oxygen carrier for chemically looped hydrogen production according to claim 4, characterized in that, The active component is Fe2O3, and the inactive components include ZrO2 and Y2O3; Fe2O3 accounts for 50-95% of the total weight of Fe2O3, ZrO2, and Y2O3, while ZrO2 and Y2O3 account for 5-50% of the total weight of Fe2O3, ZrO2, and Y2O3.

6. The oxygen carrier for chemically looped hydrogen production according to claim 5, characterized in that, The particle size of Fe2O3 is 1 μm; the particle size of ZrO2 is 500 nm; and the particle size of Y2O3 is 50 nm.

7. The oxygen carrier for chemically looped hydrogen production according to claim 1, characterized in that, The particle size range of the active component is 20 nm to 2 μm, and the particle size range of the inactive component is 5 nm to 2 μm.

8. The oxygen carrier for chemically looped hydrogen production according to claim 2, characterized in that, The particle size range of the secondary active component is 5 nm to 2 μm.

9. A method for preparing an oxygen carrier for chemically looped hydrogen production, characterized in that, The method for preparing the oxygen carrier for chemical chain hydrogen production according to claim 2 includes the following steps: S10. Mix the active component, the secondary active component, and the inactive component in a certain proportion to obtain a mixture powder; S20. Granulate the powder into shape; 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.

10. The preparation method according to claim 9, characterized in that, Between steps S10 and S20, there is also step S15: 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.

11. The preparation method according to claim 9, characterized in that, In step S10, the weight of the active component accounts for 50-95% 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 5-50% of the total weight of the active component, the secondary active component, and the inactive component.

12. The preparation method according to claim 10, characterized in that, In step S15, when the mixed powder is heat-treated in the heating furnace, the heating process adopts a programmed heating process 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 800 to 1300℃.

13. The preparation method according to claim 12, characterized in that, In step S20, mechanical granulation is used to form granules, and the resulting particles have a kinetic equivalent diameter of 1 mm to 9 mm.

14. The preparation method according to claim 13, characterized in that, In step S30, when the granulated particles are heat-treated in a heating furnace, the heating process adopts programmed heating with a heating rate of 10-35 / min. When 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 to 1300℃.

15. A multi-stage coupled chemical chain hydrogen production method, characterized in that, This method uses the following multi-stage coupled chemical chain hydrogen production device, namely: The multi-stage coupled chemical chain hydrogen production device includes a first chemical chain reaction unit and a second chemical chain reaction unit. 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. 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. 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. 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. 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. 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. 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. The multi-stage coupled chemical chain hydrogen production method includes the following steps: 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. 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. 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. 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. 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. 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. 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. The multi-stage coupled chemical chain hydrogen production device includes a first chemical chain reaction unit and a second chemical chain reaction unit. 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. 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. 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. 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. 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. 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. 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. The first oxygen carrier includes an active component and an inactive component. The active component includes Fe2O3 or Fe3O4, and the inactive component includes one or more of Al2O3, MgO, ZrO2, Y2O3, stabilized zirconium oxide, MgAl2O4, CaAl2O4, TiO2, and CaO. The active component accounts for 50-95% of the total weight of the active and inactive components; the inactive component accounts for 5-50% of the total weight of the active, secondary, and inactive components. 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.

16. The multi-stage coupled chemical chain hydrogen production method according to claim 15, characterized in that, 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.

17. The multi-stage coupled chemical chain hydrogen production method according to claim 15, characterized in that, The first oxygen carrier further includes a secondary active component, which is one or more selected from MoO3, GeO2, WO3, Mn2O3, ZnO, CeO2, and CoO. 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. The particle size range of the secondary active ingredient is 5 nm to 5 μm.

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