A modified calcium-manganese-based perovskite oxygen carrier with balanced performance and a preparation method thereof

Abstract

The application belongs to the technical field of chemical looping combustion, and particularly discloses a modified calcium-manganese-based perovskite-type oxygen carrier with balanced performance and a preparation method thereof. 0.5 Ti 0.25 Fe 0.125 Mg 0.125 O 3‑δ , and the preparation method is as follows: (1) mixing precursors of Ca, Mn, Ti, Fe and Mg elements; (2) adding the precursors into a solvent to mix and homogenize to obtain a slurry; (3) drying the homogenized precursor slurry; (4) shaping the homogenized precursor dry matter; (5) high-temperature calcining the shaped precursor; and (6) crushing and screening the calcined product to obtain the modified calcium-manganese-based perovskite-type oxygen carrier. The oxygen carrier has balanced oxygen carrying capacity, cycle stability, reaction performance, sintering and agglomeration resistance, service life and preparation cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical looping combustion, and particularly relates to a modified calcium-manganese-based perovskite-type oxygen carrier with balanced performance. BACKGROUND

[0002] Direct combustion of fossil fuels will result in a large amount of carbon dioxide greenhouse gas emissions, aggravate the greenhouse effect, and further cause global climate change. Reducing carbon emissions generated by human activities is an important measure to alleviate the greenhouse effect and control global climate change. In order to achieve this goal, carbon capture and storage is considered to be an effective strategy for reducing carbon emissions in the combustion process. Among many low-carbon combustion technologies, chemical looping combustion technology has the significant advantages of low carbon capture energy consumption and cost, high system efficiency, and simple carbon capture process, which has attracted widespread attention from researchers.

[0003] In the chemical looping combustion process, the oxygen carrier is in a core position. The oxygen carrier is usually composed of a redox pair of reducible transition metal oxides. Through the alternating occurrence of redox reactions at high temperatures, the transfer of lattice oxygen and heat is realized. In the reduction reaction, the high-valence state oxygen carrier transfers lattice oxygen to the fuel to realize the conversion of the fuel. In this reaction, solid-state lattice oxygen replaces gaseous oxygen to make the fuel burn, and nitrogen is excluded from the combustion process, so the combustion products (mainly carbon dioxide, water vapor, etc.) will not be diluted by nitrogen. By condensing the flue gas to separate the water vapor therein, low-cost in-situ separation of carbon dioxide can be achieved. Subsequently, the low-valence state oxygen carrier that has released lattice oxygen is contacted with an oxidizing atmosphere (usually air) at high temperature to undergo oxidation reaction, and the low-valence state oxygen carrier is oxidized to high-valence state oxygen carrier to realize the regeneration of lattice oxygen. As can be seen, in the chemical looping combustion process, the oxygen carrier replaces air to support the combustion and conversion of the fuel, and transfers heat between the oxidation and reduction reactions. Therefore, the performance of the oxygen carrier directly determines the overall performance of the entire chemical looping combustion process.

[0004] To date, more than 3000 oxygen carriers have been proposed and tested. Common oxygen carrier materials include iron-, copper-, manganese-, nickel- and cobalt-based metal oxides, etc. A large number of studies have shown that in the process of chemical looping combustion, oxygen carriers need to meet a series of technical requirements, such as high oxygen carrying capacity, high reactivity towards fuels, good anti-sintering and agglomeration performance, high chemical stability, wear resistance, low cost, safety and non-toxicity, etc. However, oxygen carriers with a single active component often have some defects. Among them, iron-based oxygen carriers have low reactivity and slow reaction rate; copper-based oxygen carriers are prone to sintering and agglomeration; manganese-based oxygen carriers have poor mechanical strength and are prone to wear; nickel-based oxygen carriers are not only expensive, but also prone to carbon deposition and deactivation due to sulfur poisoning; cobalt-based oxygen carriers have high toxicity to the environment. Even if a composite oxygen carrier is prepared using two active components, it can compensate for the above defects to some extent, but there are often differences in physical properties between the two active components, and different components are prone to segregation and separation in long-term chemical looping combustion cycles. In summary, the existence of the above defects limits the application of oxygen carriers and is not conducive to the further development of chemical looping combustion technology. After decades of research, chemical looping combustion technology has entered the megawatt pilot demonstration stage, and there is an urgent need for an oxygen carrier with balanced performance that meets the requirements of industrial demonstration.

[0005] In recent years, perovskite materials have attracted widespread attention from researchers in the fields of thermoelectric conversion, electronics, electromagnetism, catalysis, etc. due to their unique physical and chemical properties, and have shown excellent performance. The structure of perovskite materials can be represented by the general formula AB 3-δ O δ , where A represents an alkaline earth metal or rare earth metal ion, B represents a transition metal or P-block metal ion, and δ represents oxygen vacancies that satisfy the valence state conservation of each element in the perovskite structure. Perovskite structure allows flexible element doping and substitution to improve performance. In the field of chemical looping combustion technology, some perovskite materials are considered to have the potential to become high-performance oxygen carriers due to their excellent redox performance, thermal stability or mechanical properties, etc. such as LaCoO 3-δ and LaMnO 3-δ (Sarshar Z, Kleitz F, Kaliaguine S. Novel oxygen carriers for chemical looping combustion: La 1-x Ce xBO3(B=Co,Mn)perovskites synthesized by reactive grindingand nanocasting[J].Energy&Environmental Science,2011,4(10):4258-4269.), SrFeO3(Marek E,Hu W,Gaultois M,et al.The use of strontium ferrite in chemicallooping systems[J].Applied Energy,2018,223:369-382.), SrMnO 3-δ (KsepkoE.Perovskite-type Sr(Mn 1-x Ni x )O3materials and their chemical-looping oxygentransfer properties[J].International Journal of Hydrogen Energy,2014,39(15):8126-8137.),CaCoO 3-δ (Son EN, Baek SH, Lee R, et al. Study on the redox characteristics of CaCo based oxygen carrier for Chemical Looping Combustion[J]. Chemical Engineering Journal, 2019, 377: 121522.) etc. To achieve high performance, the aforementioned perovskite oxygen carriers often use expensive rare earth metals as A-site elements, such as La and Sr, or relatively expensive Co at the B-site. This is not conducive to reducing costs during mass production of oxygen carriers. CaMnO 3-δ Perovskite is inexpensive, but when used as an oxygen carrier in chemical looping combustion, it undergoes irreversible phase decomposition after multiple redox cycles, resulting in CaMnO. 3-δ The phase decomposes into CaMn2O4 and Ca2MnO4 spinel phases, and the spinel phase cannot be re-oxidized into CaMnO4. 3-δ Phase, which leads to CaMnO 3-δ It cannot serve as a stable oxygen carrier in long-term cycling. There are also studies targeting CaMnO. 3-δWork has been done on doping and modifying perovskites, but in these improvements, some researchers have again used expensive rare earth elements for doping (Galinsky N, Mishra A, Zhang J, et al. Ca 1-x A x MnO3(A=Sr and Ba)perovskite based oxygen carriers for chemical looping with oxygen uncoupling (CLOU)[J]. Applied Energy, 2015, 157:358-367. Furthermore, elemental doping does not always yield good results; it may even lead to the formation of secondary phases in the oxygen carrier (Galinsky N, Sendi M, Bowers L, et al. CaMn 1-x B x O 3-δ (B=Al,V,Fe,Co,and Ni)perovskite based oxygen carriers for chemical looping with oxygen uncoupling (CLOU)[J]. Applied Energy, 2016, 174:80-87.), severe aggregation and defluidization (Arjmand M, Hedayati A, Azad AM, et al. Ca x La 1-x Mn 1-y M y O 3-δ (M=Mg,Ti,Fe,or Cu)as Oxygen Carriers for Chemical-Looping with Oxygen Uncoupling (CLOU)[J].Energy&Fuels,2013,27(8):4097-4107.) etc. Single-element doping often only targets CaMnO. 3-δ Improving a particular property of perovskite, even with simultaneous doping of multiple elements, cannot completely eliminate all defects. For example, Professor Li Zhenshan's research group at Tsinghua University developed an industrially scalable CaMn... 0.5 Ti 0.375 Fe 0.125 O 3-δLiu L, Li Z, Wang Y, et al. Industry-scale production of a perovskite oxide as oxygen carrier material in chemical looping [J]. Chemical Engineering Journal, 2022, 431: 134006. ), but serious agglomeration also appeared in further tests, which limited its application in fluidized bed (Miao Z, Shen L, Li Z, et al. Sintering and agglomeration characteristics of industrially prepared CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ perovskite oxygen carrier inchemical looping combustion[J]. Chemical Engineering Journal, 2023, 472: 144722. ).

[0006] It can be seen that the current perovskite oxygen carrier is difficult to balance the cost and performance. Therefore, how to design a low-cost and relatively high-performance balanced oxygen carrier is very important for promoting the development of chemical looping combustion technology. SUMMARY

[0007] In view of the above problems, the present application provides a modified calcium-manganese-based perovskite oxygen carrier with balanced performance.

[0008] To achieve the above purpose, the present application adopts the following technical solutions:

[0009] According to a first aspect of the present application, the present application first provides a modified calcium-manganese-based perovskite oxygen carrier, the general formula of the oxygen carrier is CaMn 1-x-y-z Ti x Fe y Mg z O 3-δ , wherein x = 0.25, y = 0.125, z = 0.125, and the value of δ is in the range of 0 < δ ≤ 0.5.

[0010] Further, the value of δ at 20-25℃ is 0.1875.

[0011] According to a second aspect of the present application, the present application further provides a preparation method of the modified calcium-manganese-based perovskite-type oxygen carrier, comprising the following steps:

[0012] Step (1): mixing each of the precursors of Ca, Mn, Ti, Fe and Mg elements in a molar ratio of 8:4:2:1:1;

[0013] Step (2): adding the precursor mixture obtained in step (1) into a solvent to mix homogeneously to obtain a slurry;

[0014] Step (3): drying the homogeneous precursor slurry obtained in step (2);

[0015] Step (4): shaping the homogeneous precursor dry product obtained in step (3);

[0016] Step (5): calcining the shaped precursor obtained in step (4);

[0017] Step (6): crushing and sieving the calcined product obtained in step (5) to obtain the modified calcium-manganese-based perovskite-type oxygen carrier.

[0018] According to an embodiment of the present application, in step (1), the precursor of each element is one or more of the oxides, hydroxides and salts of the corresponding element.

[0019] Preferably, the precursor of Ca is Ca(OH)2, the precursor of Mn is Mn3O4, the precursor of Ti is TiO2, the precursor of Fe is Fe2O3, and the precursor of Mg is MgO.

[0020] According to an embodiment of the present application, in step (2), the homogeneous manner of the precursor mixture is wet ball milling, the solvent used in the wet ball milling is ethanol, water or an ethanol aqueous solution, the mass ratio of the precursor mixture to the solvent is 1:(1-20), the rotation speed of the ball mill is 50-600 revolutions per minute, and the ball milling time is 0.5-12 hours.

[0021] According to an embodiment of the present application, the mass ratio of the precursor mixture to the solvent is 1:2, the rotation speed of the ball mill is 300 revolutions per minute, and the ball milling time is 6 hours.

[0022] According to an embodiment of the present application, in step (4), the shaping is hydraulic shaping, the pressure of the hydraulic shaping is 2-15 megapascals, and the pressure maintaining time is 1-60 seconds. Preferably, the hydraulic shaping pressure is 10 megapascals, and the shaping time is 20 seconds.

[0023] According to one embodiment of the present application, in step (5), the calcination is performed under an air atmosphere, the calcination temperature is 900-1500 DEG C, and the calcination time is 0.5-12 hours.

[0024] According to one embodiment of the present application, in step (5), the procedure of the calcination is as follows: heating from 20 DEG C to 950 DEG C at a heating rate of 10 DEG C per minute, heating from 950 DEG C to 1350 DEG C at a heating rate of 2 DEG C per minute, calcination at 1350 DEG C for 8 hours, cooling from 1350 DEG C to 950 DEG C at a cooling rate of 2 DEG C per minute, and then cooling from 950 DEG C to 20 DEG C at a cooling rate of 5 DEG C per minute.

[0025] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0026] The modified calcium-manganese-based perovskite-type oxygen carrier provided by the present application has high oxygen carrying capacity, stable cycle performance, can release gaseous oxygen by oxygen evolution, has strong reaction activity, high chemical and thermal stability, high wear resistance, low raw material cost and safety. The above-mentioned ratio achieves balanced performance in terms of performance (oxygen carrying capacity, reaction activity), stability (thermal stability, chemical stability, cycle stability), service life (wear resistance), cost and safety. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Maximum oxygen carrying capacity of the oxygen carrier prepared for Example 1 of the present application in the reduction experiment on the thermogravimetric analyzer;

[0028] Figure 2 Mass change of the oxygen carrier prepared for Example 1 of the present application in 100 times of oxidation-reduction cycles on the thermogravimetric analyzer;

[0029] Figure 3 Oxygen release rate and oxygen yield of the oxygen carrier prepared for Example 1 of the present application in different cycle numbers in the 100 times of oxidation-reduction cycle experiment on the thermogravimetric analyzer.

[0030] Figure 4 Fuel conversion rate of the oxygen carrier prepared for Example 1 of the present application using methane fuel in the 20 times of oxidation-reduction cycle experiment on the batch fluidized bed test bench.

[0031] Figure 5 Carbon dioxide selectivity of the oxygen carrier prepared for Example 1 of the present application using methane fuel in the 20 times of oxidation-reduction cycle experiment on the batch fluidized bed test bench.

[0032] Figure 6 Proportion of gaseous oxygen released by oxygen evolution of the oxygen carrier prepared for Example 1 of the present application in the 20 times of oxidation-reduction cycle experiment on the batch fluidized bed test bench.

[0033] Figure 7 Appearance comparison of the oxygen carrier prepared in the present application embodiment 1 before and after 100 times of anti-sintering agglomeration cycle experiment on the packed bed experiment bench, wherein Figure 7 a in the formula (1) is the appearance before 100 times of anti-sintering agglomeration cycle experiment, Figure 7 b in the formula (2) is the appearance after 100 times of anti-sintering agglomeration cycle experiment.

[0034] Figure 8 Environmental scanning electron microscope images of the oxygen carrier prepared in the present application embodiment 1 before and after 100 times of anti-sintering agglomeration cycle experiment on the packed bed experiment bench.

[0035] Figure 9 Particle internal cross-section scanning electron microscope images and element radial distribution of the oxygen carrier prepared in the present application embodiment 1 before and after 100 times of anti-sintering agglomeration cycle experiment on the packed bed experiment bench.

[0036] Figure 10 X-ray diffraction patterns of the oxygen carrier prepared in the present application embodiment 1 before and after 100 times of anti-sintering agglomeration cycle experiment on the packed bed experiment bench.

[0037] Figure 11 Wear rate of the oxygen carrier prepared in the present application embodiment 1 measured according to the standard of American Society of Mechanical Engineers ASTM D5757-11 Standard Test Method for Measurement of Attrition of Powdered Catalysts by Air Flow and Characterization of Its Properties. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0039] The present application provides a modified calcium-manganese-based perovskite-type oxygen carrier, the general formula of the oxygen carrier is CaMn 1-x-y- z Ti x Fe y Mg z O 3-δ , wherein x=0.25, y=0.125, z=0.125, the value range of δ is 0<δ≤0.5.

[0040] In some embodiments, δ has a value of 0.1875 at room temperature, i.e. 20-25℃.

[0041] Example 1

[0042] The present embodiment provides a method for preparing the oxygen carrier as described above, and the specific steps are as follows:

[0043] (1) Preparation of a precursor mixture of Ca, Mn, Ti, Fe, and Mg elements: 56.69 g of Ca(OH)2, 14.67 g of TiO2, 7.33 g of Fe2O3, 28.58 g of Mn3O4, and 3.74 g of MgO were mixed to obtain a mixture with a Ca:Mn:Ti:Fe:Mg ratio of 8:4:2:1:1. An electric mixer was used for mixing at a speed of 30 revolutions per minute for 50 minutes.

[0044] (2) Preparation of a homogeneous precursor slurry: the precursor mixture prepared in step (1) was added to 286 ml of anhydrous ethanol to obtain a slurry, and the mass ratio of the precursor mixture to anhydrous ethanol was 1:2. Then, the slurry was transferred to an alumina ball mill tank with a volume of 1 liter, and the tank was filled with about one-third of the volume of the tank with zirconia milling beads. A planetary ball mill was used for wet milling. The speed of the ball mill was 300 revolutions per minute, and the milling time was 6 hours. After wet milling, a homogeneous precursor slurry was obtained.

[0045] (3) Preparation of dry homogeneous precursors: the homogeneous precursor slurry prepared in step (2) was poured into a beaker, two magnetic stirrers were placed in the beaker, and then the beaker containing the homogeneous precursor slurry was placed on a magnetic stirrer with heating function. The stirring speed was 30 revolutions per minute, and the heating and evaporation temperature was 80°C. The slurry was completely dried into powder and small blocks.

[0046] (4) Shaping of the dry homogeneous precursors: an appropriate amount of the dry homogeneous precursors prepared in step (3) was placed in a cylindrical stainless steel mold each time, and a small manual hydraulic press was used to press the dry homogeneous precursors into a cylindrical shape. The hydraulic forming pressure was 10 megapascals, and the holding time of the forming pressure was 20 seconds.

[0047] (5) Calcination of the shaped precursors: the shaped precursors prepared in step (4) were placed in a yttria-stabilized zirconia crucible. The temperature rising program was as follows: from room temperature to 950°C at a rate of 10°C per minute, and from 950°C to 1350°C at a rate of 2°C per minute. The calcination was performed at 1350°C for 8 hours in an air atmosphere, and then the temperature was lowered according to the following program: from 1350°C to 950°C at a rate of 2°C per minute, and from 950°C to room temperature at a rate of 5°C per minute.

[0048] (6) crushing and sieving: the calcined product prepared in step (5) is crushed mechanically, and particles in the size range of 100 to 300 microns are sieved out, to obtain the modified calcium-manganese-based perovskite-type oxygen carrier CaMn 0.5 Ti 0.25 Fe 0.125 Mg 0.125 O 2.8125 .

[0049] Application test

[0050] The CaMn 0.5 Ti 0.25 Fe 0.125 Mg 0.125 O 3-δ The performance evaluation of the perovskite-type oxygen carrier was carried out as follows.

[0051] 1. Maximum oxygen carrying capacity test of oxygen carrier

[0052] The test was carried out on a thermogravimetric analyzer. 7.6 mg of oxygen carrier was weighed and placed in an alumina crucible, which was then placed on the balance of the thermogravimetric analyzer, and subjected to deep reduction. The reduction reaction temperature was 900°C, the reduction atmosphere was a mixture of 10% hydrogen and 90% argon, the total gas flow rate was 100 standard cubic centimeters per minute, and the reduction time was 150 minutes. By measuring the mass change curve of the oxygen carrier due to the loss of lattice oxygen during continuous deep reduction, the maximum oxygen carrying rate of the oxygen carrier was calculated. The test results showed that, as shown in Figure 1 , the oxygen carrier continuously lost lattice oxygen under the reduction atmosphere, and after about 150 minutes, the weight loss rate (mass loss / initial mass) was 15.37%, indicating that the oxygen carrying capacity of the oxygen carrier was excellent, with an oxygen carrying rate as high as 15.37%.

[0053] 2. Long-term redox cycle stability test of oxygen carrier

[0054] The test was carried out on a thermogravimetric analyzer. 30.5 mg of oxygen carrier was weighed and placed in an alumina crucible, which was then placed on the balance of the thermogravimetric analyzer, and subjected to 100 cycles of oxidation and reduction. The test temperature was 900°C. The reduction phase was 10% hydrogen for 120s, the oxidation phase was 10% oxygen for 150s, and there was a 150s purging process between the oxidation and reduction procedures, with argon as the balance gas and purging gas. The total gas flow rate was constant at 100 standard cubic centimeters per minute. The cycle stability of the oxygen carrier was evaluated by measuring the mass change of the oxygen carrier during multiple oxidation and reduction cycles. The test results showed that, as shown in Figure 2 , the oxygen carrier had no obvious activation effect and stable cycle performance. As shown in Figure 3As shown, the oxygen carrier has stable oxygen release rate and oxygen uptake rate in 100 cycles, and the values of the two are consistent; indicating that the oxygen carrier has stable performance and the oxygen carrying capacity does not decrease with the increase of cycle number.

[0055] 3. Evaluation of oxygen carrier reactivity and oxygen uncoupling characteristics

[0056] The test was carried out on a fluidized bed reactor, using about 37 g of the oxygen carrier, and the test temperature was 950°C. The oxidation atmosphere was a mixed gas of 86.4% air + 13.6% steam, with a total flow rate of 1100 standard cubic centimeters per minute, and the oxidation time was 310 seconds; the reduction atmosphere was a mixed gas of 75% nitrogen + 15% steam + 10% methane, with a total flow rate of 1000 standard cubic centimeters per minute, and the reduction time was 110 seconds. A flue gas analyzer was used to detect and record the composition of the gas at the outlet of the reactor, to evaluate the reaction performance of the oxygen carrier on the methane gas fuel and the oxygen uncoupling characteristics of the oxygen carrier. The test results show that, as shown in Figure 4 , the conversion rate of the oxygen carrier on the methane can reach 98.8% in 20 cycles of methane fuel chemical looping combustion experiments. As shown in Figure 5 , the oxygen carrier has excellent chemical looping combustion performance, and the selectivity of carbon dioxide in the combustion products is always higher than 99.5%. As shown in Figure 6 , the oxygen carrier has oxygen uncoupling characteristics, and releases 0.11 w.% of gaseous oxygen based on the initial mass during the chemical looping combustion process. The above results show that the oxygen carrier has excellent reaction performance.

[0057] 4. Test of sintering and agglomeration resistance of oxygen carrier

[0058] The test was carried out on a fixed bed reactor, using about 30 g of the oxygen carrier, and the test temperature was 950°C, and 100 cycles of oxidation and reduction reactions were carried out. In each cycle, the oxidation atmosphere was a mixed gas of 10% oxygen and 90% nitrogen, and the reduction atmosphere was a mixed gas of 10% hydrogen and 90% nitrogen, with a gas flow rate of 833 standard cubic centimeters per minute. The reduction depth was to release 3% mass fraction of lattice oxygen. The appearance of the oxygen carrier particles before and after the sintering and agglomeration resistance test was observed and recorded, and the results show that, as shown in Figure 7 a and Figure 7 b in the figure, no particle agglomeration was observed before and after the sintering and agglomeration resistance test of the oxygen carrier. The surface morphology of the perovskite-type oxygen carrier before, during and after the sintering and agglomeration resistance test was observed using a scanning electron microscope. The results show that, as shown in Figure 8 , the oxygen carrier did not sinter during the test. The above results show that the oxygen carrier has excellent thermal stability and can resist sintering and agglomeration at high temperatures. The cross-sectional element distribution of the oxygen carrier particles before and after the sintering and agglomeration resistance test was tested using a scanning electron microscope coupled with an energy dispersive spectrometer, and the red line in the figure is the position of the cross-sectional EDS line scan. The results show that, as shown inFigure 9 As shown, the elements are evenly distributed in the radial direction, without migration and segregation, and have chemical stability. The phase composition of the oxygen carriers before and after the anti-sintering agglomeration test was analyzed using X-ray diffraction technology, and the results showed that, as shown in Figure 10 the phase composition remained consistent before and after the test, and the oxygen carrier had chemical stability.

[0059] 5. Abrasion resistance test of the oxygen carrier

[0060] The test was performed on a test device that met the standard of American Society of Mechanical Engineers ASTM D 5757-11 "Standard Test Method for Determining Abrasion and Characterization of Properties of Powdered Catalysts by Air Flow", 50 g of the oxygen carrier was used, the test temperature was room temperature, the air flow was 10 L per minute, and the test duration was 5 hours. By collecting and weighing the fine powder mass generated by particle abrasion, the abrasion rate and abrasion service life of the oxygen carrier were calculated. The results showed that, as shown in Figure 11 the average abrasion rate of the modified calcium-manganese-based perovskite-type oxygen carrier was only 0.012 wt.%·h -1 , and the expected abrasion life was as high as 8333 hours.

[0061] Those skilled in the art will readily understand that the above description is only the preferred embodiments of the present application, and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A modified calcium-manganese-based perovskite-type oxygen carrier, characterized by, The oxygen carrier has a general formula of CaMn 1-x-y- z Ti x Fe y Mg z O 3-δ wherein x = 0.25, y = 0.125, z = 0.125, and the delta value ranges from 0.1875 to 0.

5.

2. A method for producing the modified calcium-manganese-based perovskite-type oxygen carrier according to claim 1, characterized by, The preparation method comprises the following steps: Step (1): mixing each element of Ca, Mn, Ti, Fe, Mg element corresponding precursor according to the molar ratio of 8:4:2:1:1; Step (2): adding the precursor mixture obtained in step (1) into a solvent to mix and homogenize to obtain a slurry; Step (3): drying the homogeneous precursor slurry obtained in step (2); Step (4): forming the homogeneous precursor dry product obtained in step (3); Step (5): calcining the formed precursor obtained in step (4); Step (6): crushing and sieving the calcined product obtained in step (5) to obtain the modified calcium-manganese-based perovskite-type oxygen carrier.

3. The preparation method according to claim 2, characterized in that, In step (1), the precursor of each element is one or more of the corresponding element oxides, hydroxides, and salts.

4. The production method according to claim 3, characterized by, The precursor of Ca is Ca(OH)2, the precursor of Mn is Mn3O4, the precursor of Ti is TiO2, the precursor of Fe is Fe2O3, and the precursor of Mg is MgO.

5. The preparation method according to claim 2, characterized in that, In step (2), the homogenization method of the precursor mixture is wet ball milling, the solvent used in the wet ball milling is ethanol, water or ethanol aqueous solution, the mass ratio of the precursor mixture to the solvent is 1: (1-20), the rotation speed of the ball mill is 50-600 revolutions per minute, and the ball milling time is 0.5-12 hours.

6. The production method according to claim 5, wherein The mass ratio of the precursor mixture to the solvent is 1:2, the rotation speed of the ball mill is 300 revolutions per minute, and the ball milling time is 6 hours.

7. The preparation method according to claim 2, characterized in that, In step (4), the forming is hydraulic forming, the pressure of the hydraulic forming is 2-15 megapascals, and the pressure maintaining time is 1-60 seconds.

8. The preparation method according to claim 7, characterized in that, The hydraulic forming pressure is 10 megapascals, and the forming time is 20 seconds.

9. The preparation method according to claim 2, characterized in that, In step (5), the calcination is carried out in an air atmosphere, the calcination temperature is 900-1500℃, and the calcination time is 0.5-12 hours.

10. The production method according to claim 2 or 9, characterized by, In step (5), the calcination program is: heating from 20℃ to 950℃ at a heating rate of 10℃ per minute, heating from 950℃ to 1350℃ at a heating rate of 2℃ per minute, calcining at 1350℃ for 8 hours, cooling from 1350℃ to 950℃ at a cooling rate of 2℃ per minute, and then cooling from 950℃ to 20℃ at a cooling rate of 5℃ per minute.

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