Cu-Mg-Ca ternary metal bifunctional material and preparation method thereof, and CO2 capture and in-situ utilization method

Abstract

The invention relates to a Cu-Mg-Ca ternary metal bifunctional material and a preparation method thereof, and a CO2 capture and in-situ utilization method. The Cu-Mg-Ca ternary metal bifunctional material contains a Cu element, a Mg element and a Ca element, the atomic ratio of the Cu element to all metal elements is 0.1%-1%, the atomic ratio of the Mg element to all metal elements is 5%-15%, the Cu element exists in the form of Cu metal, the Mg element exists in the form of MgO, and the Ca element exists in the form of CaO. The Cu-Mg-Ca ternary metal bifunctional material disclosed by the invention is excellent in catalytic effect, capable of relieving sintering and inactivation of the bifunctional material and excellent in cycling stability.

Description

Technical Field

[0001] This invention relates to a Cu-Mg-Ca ternary metal bifunctional material and its preparation method, as well as a method for CO2 capture and in-situ utilization, belonging to the field of environmental protection, specifically to the field of CO2 capture, utilization and storage. Background Technology

[0002] Since the Industrial Revolution, excessive CO2 emissions from human industrial activities have been the primary cause of the greenhouse effect, leading to global climate disasters such as extreme heat, drought, and ocean acidification, which have severely impacted the survival of life on Earth.

[0003] The widespread use of fossil fuels is the root cause of large-scale CO2 emissions and the greenhouse effect. However, humanity still heavily relies on fossil fuels and will continue to emit CO2. Therefore, CO2 emission control has become an urgent problem to be solved in my country's energy and related industries. Carbon dioxide capture, utilization, and storage (CCUS) is one of the most promising large-scale carbon reduction technologies, mainly consisting of four parts: i) carbon dioxide capture, ii) carbon dioxide compression, storage, and transportation, iii) carbon dioxide utilization, and iv) carbon dioxide storage. This technology uses adsorbents to capture CO2 from flue gas from thermal power plants, metallurgical waste gas, and cement kiln exhaust gas, and then transports it to chemical plants for utilization or to geological landfills such as abandoned oil fields for geological storage through compression liquefaction and pipeline transportation.

[0004] Currently, all components of CCUS (Chemical Coal Gas Capture and In-situ Utilization) are implemented discretely. The enormous energy consumption for CO2 capture, CO2 compression, storage, and transportation, as well as CO2 utilization, restricts the industrial-scale operation of CCUS technology. To address the energy consumption issue of CCUS technology, researchers have recently proposed an integrated flue gas CO2 capture and in-situ utilization (ICCU) technology. This technology captures approximately 15 vol.% of CO2 in flue gas using an adsorbent in a bifunctional material (the adsorbent component is converted into carbonate). Subsequently, renewable green hydrogen, under the action of a catalyst component in the bifunctional material, converts the carbonate in-situ into high-value CO, and regenerates the carbonate into fresh adsorbent material. The bifunctional material can efficiently capture CO2 and convert it in-situ into high-value products through multiple cycles of reaction.

[0005] The advantage of ICCU technology lies in its in-situ integration of CO2 capture and CO2 utilization. This avoids the CO2 compression and liquefaction, as well as the CO2 storage and transportation steps between CO2 capture and utilization, significantly reducing the energy consumption and cost of CCUS (Continuous Coal-to-gas) technology. The core of ICCU technology lies in the design and development of bifunctional materials. The CO2 capture capacity of the adsorbent component in bifunctional materials decreases with repeated cycles as the reaction proceeds, while the catalyst component also undergoes sintering and particle aggregation during repeated cycles. In particular, the catalyst component often interacts with the adsorbent, thereby reducing the number of active sites on the adsorbent.

[0006] CO is a fundamental raw material in chemical processes such as Fischer-Tropsch synthesis and has enormous application potential in the chemical industry. In recent years, capturing CO2 in flue gas and converting it in situ into CO has proven to be a promising application method. CaO-based adsorbents are considered the most promising high-temperature CO2 adsorbents, possessing advantages such as high theoretical CO2 adsorption capacity, excellent chemical reaction kinetics, and abundant natural reserves.

[0007] Currently, Ni-Ca and Fe-Ca bifunctional materials have been proven to possess certain CO2 capture and in-situ conversion properties. Ni-Ca bifunctional materials exhibit excellent reactivity, but the CO product selectivity is slightly low. Fe-Ca bifunctional materials, on the other hand, show good CO product selectivity in the reaction, but Fe is readily oxidized by CO2, and high Fe loadings can also consume CaO active sites in the bifunctional material (generating CaFe2O4), thus reducing the CO2 capture capacity of the bifunctional material. Summary of the Invention

[0008] Problem to be solved by the invention

[0009] To address the problems existing in the prior art, this invention provides a Cu-Mg-Ca ternary metal bifunctional material and its preparation method, as well as a method for CO2 capture and in-situ utilization. The Cu-Mg-Ca ternary metal bifunctional material of this invention exhibits excellent catalytic effect, alleviates sintering and deactivation of bifunctional materials, and demonstrates excellent cycle stability.

[0010] Solution for solving the problem

[0011] This invention provides a Cu-Mg-Ca ternary metal bifunctional material, wherein the bifunctional material contains Cu, Mg, and Ca elements, wherein...

[0012] Cu accounts for 0.1% to 1% of the atomic composition of all metallic elements.

[0013] Mg accounts for 5% to 15% of the atomic percentage of all metallic elements.

[0014] Cu exists as Cu metal, Mg exists as MgO, and Ca exists as CaO.

[0015] The present invention also provides a method for preparing a Cu-Mg-Ca ternary metal bifunctional material according to the present invention, the preparation method comprising the following steps:

[0016] S1: Add the precursors of Cu, Mg, and Ca to deionized water according to the atomic ratio described in claim 1, stir until completely dissolved, and obtain a solution;

[0017] S2: Add citric acid to the above solution and stir;

[0018] S3: Stir and heat the solution obtained in S2 until a wet gel is obtained;

[0019] S4: Dry and age the wet gel to obtain a dry gel;

[0020] S5: The dry gel is heated to 800-850°C for 2-4 hours at a heating rate of 60-100°C / min, and then rapidly cooled at a cooling rate of 60-100°C / min to obtain Cu-Mg-Ca bifunctional material powder.

[0021] S6: Granulate the Cu-Mg-Ca bifunctional material powder to obtain Cu-Mg-Ca ternary metal bifunctional material.

[0022] According to the preparation method of the present invention, in step S1, the precursor of Cu is copper nitrate, the precursor of Mg is magnesium nitrate, and the precursor of Ca is calcium nitrate.

[0023] According to the preparation method of the present invention, in step S2, the ratio of the sum of the molar amounts of Cu, Mg and Ca metal ions to the molar amount of citric acid is 1:1 to 1:1.5.

[0024] According to the preparation method of the present invention, the stirring speed in step S3 is 200-300 rpm, the stirring heating is oil bath heating, the oil bath heating temperature is 85-95℃, and the heating time is 8-12 hours.

[0025] According to the preparation method of the present invention, the drying and aging temperature in step S4 is 110-140℃, and the drying and aging time is 8-14 hours.

[0026] According to the preparation method of the present invention, in step S6, a hydraulic granulator is used for granulation, the processing pressure is 9-11 MPa, and the particle size of the bifunctional material is 40-60 mesh.

[0027] This invention also provides a method for CO2 capture and in-situ utilization, comprising the following steps:

[0028] Step 1: Weigh the Cu-Mg-Ca ternary metal bifunctional material described in this invention and place it into the reactor;

[0029] Step 2: Heat the reactor and introduce flue gas with a CO2 concentration of 10%-17% into the reactor for CO2 capture. Stop the gas supply after the capture is completed.

[0030] Step 3: Maintain the reactor temperature as in Step 2, and add hydrogen to the reactor to produce CO in situ.

[0031] According to the CO2 capture and in-situ utilization method of the present invention, the temperature of the reactor in step two is set to 620-650℃, and the CO2 is introduced for 20-60 minutes.

[0032] According to the CO2 capture and in-situ utilization method of the present invention, the concentration of H2 in step three is 10%-100%, the time for introducing H2 is 20-60 minutes, or no more CO is generated.

[0033] Effects of the invention

[0034] In the Cu-Mg-Ca ternary metal bifunctional material of this invention, CaO serves as the active site for CO2 adsorption, capable of cyclically adsorbing CO2 from flue gas and simultaneously converting it into carbonates. MgO acts as a support, alleviating the high-temperature sintering of the bifunctional material. Meanwhile, Cu acts as a CO2 hydrogenation catalyst, converting CO2 from carbonate decomposition into high-value CO products in situ. The Cu-Mg-Ca ternary metal bifunctional material of this invention exhibits excellent catalytic CO2 hydrogenation conversion rate and product selectivity, while also mitigating sintering and deactivation of the bifunctional material, thus achieving efficient CO2 capture and in-situ high-value conversion. Attached Figure Description

[0035] Figure 1 A schematic flowchart of the CO2 capture and in-situ utilization method of the present invention;

[0036] Figure 2 A schematic diagram showing the results of cyclic testing of the bifunctional materials I to II and bifunctional materials Pair I to Pair IV of the present invention;

[0037] Figure 3A schematic diagram showing the results of the second cyclic test of Application Example 1 and Application Comparative Examples 1-5 of the present invention;

[0038] Figure 4 Schematic diagram of XRD test results for bifunctional materials I to II and bifunctional materials II to IV of the present invention;

[0039] Figure 5 A schematic diagram showing the results of three cyclic tests on the bifunctional materials I to II and bifunctional materials P-I to P-IV of the present invention;

[0040] Figure 6 A schematic diagram showing the distribution of Cu in the bifunctional material-I of the present invention and the results of aberration-corrected transmission electron microscopy analysis of the CaO lattice.

[0041] Figure 7 A schematic flowchart of the preparation method of Cu-Mg-Ca ternary metal bifunctional material and the CO2 capture and in-situ utilization method of the present invention. Detailed Implementation

[0042] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0043] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0044] Unless otherwise stated, in this instruction manual, "more" in "multiple", "multi-variety", "multiple", etc., means a value of 2 or more.

[0045] In this specification, the terms “substantially,” “largely,” or “truly” mean that the error is less than 5%, or less than 3%, or less than 1% compared to the relevant perfect or theoretical standard.

[0046] Unless otherwise specified, "%" in this instruction manual refers to the percentage content by mass.

[0047] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0048] In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes both scenarios in which the event occurs and scenarios in which the event does not occur. In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one embodiment described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0049] This invention provides a Cu-Mg-Ca ternary metal bifunctional material, wherein the bifunctional material contains Cu, Mg, and Ca elements, wherein...

[0050] Cu accounts for 0.1% to 1% of the atomic composition of all metallic elements.

[0051] Mg accounts for 5% to 15% of the atomic percentage of all metallic elements.

[0052] Cu exists as Cu metal, Mg exists as MgO, and Ca exists as CaO.

[0053] The term "metallic elements" refers to the collective elements Cu, Mg, and Ca.

[0054] In the Cu-Mg-Ca ternary metal bifunctional material of the present invention, CaO, as an active site for CO2 adsorption, can cyclically adsorb CO2 in flue gas and simultaneously convert it into carbonate. MgO, as a support, can alleviate the high-temperature sintering of the bifunctional material. At the same time, Cu, as a CO2 hydrogenation catalyst, can convert the CO2 decomposed from carbonate into high-value CO products in situ.

[0055] Preferably, the Cu-Mg-Ca ternary metal bifunctional material of the present invention has a porous structure; more preferably, it has a high specific surface area, for example, preferably 20-30 μm². 2 / g is beneficial for CO2 adsorption and can also promote the diffusion of reactants and products.

[0056] In the Cu-Mg-Ca ternary metal bifunctional material of the present invention, Cu element exists in the form of Cu metal. The supported single-atom Cu metal sites not only have good conversion rate and product selectivity for catalyzing the hydrogenation of CO2 to CO, but also the single-atom Cu metal sites can further alleviate the sintering and deactivation of the bifunctional material through strong metal-support interaction, thereby realizing efficient CO2 capture and in-situ high-value conversion.

[0057] In the Cu-Mg-Ca ternary metal bifunctional material of this invention, the Cu element accounts for 0.1% to 1% of the atomic proportion of all metal elements. Generally, a decrease in the catalyst component content in a bifunctional material often means a reduction in the catalytic metal and a decrease in catalytic activity. However, Cu is an active component that easily leads to the sintering of the adsorbent component; therefore, reducing the Cu content may alleviate the sintering and deactivation of the adsorbent component in the bifunctional material. Conversely, an increase in the catalyst component content in a bifunctional material often means an increase in the catalytic metal and an increase in catalytic activity. However, Cu is an active component that easily leads to the sintering of the adsorbent component; therefore, increasing the Cu content may promote the sintering and deactivation of the adsorbent component in the bifunctional material. In this invention, the Cu element at the aforementioned content exists in the form of supported single-atom Cu metal sites. This not only exhibits good conversion rate and product selectivity for the catalytic hydrogenation of CO2 to CO, but also, through strong metal-support interactions, the single-atom Cu metal sites can further alleviate the sintering and deactivation of the bifunctional material, thereby achieving efficient CO2 capture and in-situ high-value conversion.

[0058] In the Cu-Mg-Ca ternary bifunctional metal material of this invention, Mg accounts for 5% to 15% of the atomic proportion of all metal elements. MgO, as an inert support, can effectively suppress sintering and deactivation of the bifunctional material when uniformly dispersed within it; however, MgO itself has no CO2 capture capacity or catalytic activity in this reaction system, and excessive MgO doping will reduce the number of CO2 adsorption sites per unit mass in the bifunctional material, thereby increasing reaction energy consumption. Therefore, Mg accounts for 5% to 15% of the atomic proportion of all metal elements.

[0059] The present invention also provides a method for preparing a Cu-Mg-Ca ternary metal bifunctional material according to the present invention, the preparation method comprising the following steps:

[0060] S1: Add the precursors of Cu, Mg, and Ca to deionized water according to the atomic ratio described in claim 1, stir until completely dissolved, and obtain a solution;

[0061] S2: Add citric acid to the above solution and stir;

[0062] S3: Stir and heat the solution obtained in S2 until a wet gel is obtained;

[0063] S4: Dry and age the wet gel to obtain a dry gel;

[0064] S5: The dry gel is heated to 800-850°C for 2-4 hours at a heating rate of 60-100°C / min, and then rapidly cooled at a cooling rate of 60-100°C / min to obtain Cu-Mg-Ca bifunctional material powder.

[0065] Preferably, the dry gel is heated to 850°C for 2 hours at a heating rate of 80°C / min and then rapidly cooled at a cooling rate of 100°C / min to obtain Cu-Mg-Ca bifunctional material powder.

[0066] S6: Granulate the Cu-Mg-Ca material powder to obtain a Cu-Mg-Ca ternary metal bifunctional material.

[0067] According to the preparation method of the present invention, in step S1, the precursor of Cu is copper nitrate, the precursor of Mg is magnesium nitrate, and the precursor of Ca is calcium nitrate.

[0068] According to the preparation method of the present invention, in step S1, the ratio of the sum of the moles of Cu, Mg and Ca metal ions to the moles of deionized water is 1:30 to 1:50.

[0069] According to the preparation method of the present invention, in step S2, the ratio of the sum of the molar amounts of Cu, Mg and Ca metal ions to the molar amount of citric acid is 1:1 to 1:1.5.

[0070] According to the preparation method of the present invention, in step S3, the stirring speed is 200-300 rpm, the stirring heating is oil bath heating, the oil bath heating temperature is 85-95℃, preferably 85℃, and the heating time is 8-12 hours.

[0071] According to the preparation method of the present invention, the drying and aging temperature in step S4 is 110-140℃, preferably 120℃, and the drying and aging time is 8-14 hours.

[0072] According to the preparation method of the present invention, in step S6, a hydraulic granulator is used for granulation, the processing pressure is 9-11 MPa, and the particle size of the bifunctional material is 40-60 mesh.

[0073] This invention also provides a method for CO2 capture and in-situ utilization, comprising the following steps:

[0074] Step 1: Weigh the Cu-Mg-Ca ternary metal bifunctional material as described in claim 1 and place it into the reactor;

[0075] Step 2: Heat the reactor and introduce flue gas with a CO2 concentration of 10%-17% into the reactor for CO2 capture. Stop the gas supply after the capture is completed.

[0076] Step 3: Maintain the reactor temperature as in Step 2, and add hydrogen to the reactor to produce CO in situ.

[0077] like Figure 1 As shown in (b), after the bifunctional material of the present invention is placed in the reactor, CO2 in the flue gas is captured by the adsorbent in the bifunctional material (the adsorbent component is converted into carbonate); subsequently, under the action of the catalyst component in the bifunctional material, the carbonate is converted into high-value CO (a basic chemical raw material) in situ through a renewable hydrogen source, and the carbonate is regenerated into fresh adsorbent material. The bifunctional material can efficiently capture CO2 and convert it into high-value products in situ in multiple cyclic reactions.

[0078] The reactor is preferably a fixed-bed reactor.

[0079] According to the CO2 capture and in-situ utilization method of the present invention, the temperature of the reactor in step two is set to 620-650℃, more preferably 650℃, and the CO2 is introduced for 20-60 minutes.

[0080] Preferably, the CO2 capture and in-situ utilization method of the present invention is carried out in-situ in the same reactor using the bifunctional material. The CO2 capture (carbonation) temperature is preferably 620-650℃, more preferably 650℃, and the reaction temperature for in-situ CO preparation by carbonate hydrogenation (regeneration) is preferably 620-650℃, more preferably 650℃. The CO2 capture (carbonation) and in-situ CO preparation by carbonate hydrogenation (regeneration) are preferably completed under isothermal conditions, which can significantly reduce process energy consumption. When the temperature is below 620℃, the CO2 capture kinetics are slow, and CO2 in the flue gas cannot be captured effectively. Simultaneously, the carbonate decomposition rate is even slower, easily causing a mismatch between the CO2 capture and carbonate hydrogenation reactions. When the temperature is above 650℃, the carbonate hydrogenation conversion rate is too fast, easily leading to CO2 escape, i.e., the CO2 product does not have enough time to undergo a reverse water-gas shift reaction with H2 to convert into CO.

[0081] According to the CO2 capture and in-situ utilization method of the present invention, the concentration of H2 in step three is 10%-100%, the time for introducing H2 is 20-60 minutes, or no more CO is generated.

[0082] Examples

[0083] Example 1

[0084] S1: Add copper nitrate, magnesium nitrate hexahydrate, and calcium nitrate tetrahydrate to deionized water, stir until completely dissolved, and obtain a solution; wherein, Cu element accounts for 0.1% of the atomic ratio of all metal elements, Mg element accounts for 10% of the atomic ratio of all metal elements, and the molar ratio of metal ions to deionized water is 1:40.

[0085] S2: Add citric acid to the above solution and stir. The molar ratio of metal ions to citric acid is 1:1.

[0086] S3: Place the solution obtained in S2 in an oil bath and heat it at 85°C until a wet gel is obtained. The stirring speed is 300 RPM.

[0087] S4: The wet gel is placed in an oven to dry and age at a temperature of 120°C to obtain a dry gel.

[0088] S5: The dry gel is heated to 850°C for 2 hours at a heating rate of 80°C / min, and then rapidly cooled (100°C / min) to obtain Cu-Mg-Ca material powder.

[0089] S6: The Cu-Mg-Ca material powder is granulated on a hydraulic granulator at a pressure of 10 MPa. The particle size of the bifunctional material is 40-60 mesh, and the Cu-Mg-Ca ternary metal bifunctional material is obtained, which is denoted as bifunctional material-I.

[0090] Example 2

[0091] The atomic ratio of Cu to all metal elements was adjusted to 1%, and the atomic ratio of Mg to all metal elements was adjusted to 10%. The Cu-Mg-Ca ternary metal bifunctional material was obtained in the same manner as in Example 1, and it is referred to as bifunctional material-II.

[0092] Comparative Example 1

[0093] Commercially available CaO was used as the bifunctional material (Aladdin, purity >99%), denoted as bifunctional material-p-I.

[0094] Comparative Example 2

[0095] Without adding Cu, and with Mg accounting for 10% of all metal elements, a Mg-Ca bifunctional material was obtained using the same method as in Example 1, and is denoted as bifunctional material-pair II.

[0096] Comparative Example 3

[0097] The atomic ratio of Cu to all metal elements was adjusted to 5%, and the atomic ratio of Mg to all metal elements was adjusted to 10%. The Cu-Mg-Ca ternary metal bifunctional material was obtained in the same manner as in Example 1, and it is denoted as bifunctional material-pair III.

[0098] Comparative Example 4

[0099] The atomic ratio of Cu to all metal elements was adjusted to 20%, and the atomic ratio of Mg to all metal elements was adjusted to 10%. A Cu-Mg-Ca ternary metal bifunctional material was obtained in the same manner as in Example 1, and it is denoted as bifunctional material-pair IV.

[0100] Application Example 1

[0101] Step 1: Weigh the bifunctional material-I obtained in Example 1 and place it into the fixed-bed reactor;

[0102] Step 2: Heat the fixed-bed reactor to 650℃, and introduce flue gas with a CO2 concentration of 10% by volume into the fixed-bed reactor for CO2 capture. The gas introduction time is 30 minutes.

[0103] Step 3: Maintain the temperature of the fixed-bed reactor as in Step 2, and introduce 100% hydrogen gas by volume into the fixed-bed reactor for 30 minutes to produce CO in situ through hydrogenation.

[0104] Application Comparative Example 1

[0105] Replace bifunctional material-I with bifunctional material-pair-I, adjust the temperature of the fixed-bed reactor in steps two and three to 600°C, and perform the test as in application example 1.

[0106] Application Comparative Example 2

[0107] Replace bifunctional material-I with bifunctional material-pair I, and perform the test as in Application Example 1.

[0108] Application Comparative Example 3

[0109] Replace bifunctional material-I with bifunctional material-pair-I, adjust the temperature of the fixed-bed reactor in steps two and three to 700°C, and perform the test as in application example 1.

[0110] Application Comparative Example 4

[0111] The temperature of the fixed-bed reactor in steps two and three was adjusted to 600°C, and the rest was the same as in application example 1. The test was then conducted.

[0112] Application Comparative Example 5

[0113] The temperature of the fixed-bed reactor in steps two and three was adjusted to 700°C, and the rest was the same as in application example 1. The test was then conducted.

[0114] Performance Test

[0115] Cycling Performance Test One

[0116] Bifunctional materials I to II and bifunctional materials P-I to P-IV were weighed and placed into a fixed-bed reactor. The fixed-bed reactor was heated to 650°C, and flue gas with a CO2 concentration of 10% by volume was introduced into the fixed-bed reactor for CO2 capture for 30 minutes. The temperature of the fixed-bed reactor was maintained, and hydrogen gas with a concentration of 100% by volume was introduced into the fixed-bed reactor for 30 minutes to generate CO in situ through hydrogenation.

[0117] The above process was repeated 10 times, and the specific test results are as follows: Figure 2 As shown.

[0118] like Figure 2 As shown, the Cu-Mg-Ca ternary metal bifunctional material of the present invention exhibits superior circulating CO2 capture capacity and CO2 conversion rate. Moreover, different Cu contents have a significant impact on the circulating CO2 capture and in-situ conversion performance of the Cu-Mg-Ca ternary metal bifunctional material. Among them, bifunctional material-I (Cu0.1Mg10CaO bifunctional material) shows the best circulating CO2 capture capacity, CO2 conversion rate, and CO selectivity.

[0119] Cycling Performance Test Two

[0120] Application Example 1 and Comparative Examples 1-5 were each subjected to 10 cycles. Specific test results are as follows: Figure 3 As shown.

[0121] like Figure 3 As shown, different reaction temperatures have a significant impact on the cyclic CO2 capture and in-situ conversion performance of Cu-Mg-Ca ternary metal bifunctional materials, such as... Figure 4As shown, isothermal CO2 capture at 650℃ and in-situ isothermal hydrogenation of carbonate to CO at 650℃ exhibit optimal reactivity. At lower temperatures (e.g., 600℃), the CO2 capture reaction kinetics and CO2 capture activity are poor, and the carbonate decomposition rate during isothermal H2 reduction is slow, leading to a mismatch between CO2 capture and in-situ carbonate hydrogenation to CO reactions. At higher temperatures (e.g., 700℃), the CO2 capture reaction kinetics are better, but the CO2 capture activity is poor; furthermore, the carbonate decomposition rate is faster during isothermal H2 reduction at 700℃, causing CO2 to escape before it can be hydrogenated to CO, thus reducing the overall CO2 conversion rate.

[0122] XRD Test

[0123] XRD tests were performed on bifunctional material-I. Subsequently, bifunctional material-I was weighed and placed into a fixed-bed reactor. The fixed-bed reactor was heated to 650°C, and flue gas with a CO2 concentration of 10% by volume was introduced into the fixed-bed reactor for CO2 capture for 30 min. The temperature of the fixed-bed reactor was maintained, and hydrogen gas with a concentration of 100% by volume was introduced into the fixed-bed reactor for 30 min. CO was prepared in situ by hydrogenation to obtain the reduced bifunctional material-I, which was then subjected to XRD tests again.

[0124] The same tests were performed on bifunctional materials-II and bifunctional materials-II to IV, and the results are as follows: Figure 4 As shown.

[0125] Cycling Performance Test Three

[0126] Bifunctional materials I to II and bifunctional materials P-I to P-IV were weighed and placed into a thermogravimetric reactor. The bifunctional materials were first heated to 900℃ (to calcine the materials completely), and then cooled (40℃ / min) to 650℃. Flue gas with a CO2 concentration of 10% by volume was introduced into the thermogravimetric reactor for CO2 capture for 15 min (first cycle). Subsequently, the bifunctional materials were heated to 900℃ again and maintained in a 100% CO2 atmosphere for 2 min (carbonate decomposition and CO2 release).

[0127] The temperature was then lowered to 650°C in an N2 atmosphere, and flue gas with a CO2 concentration of 10% by volume was introduced into the thermogravimetric reactor for CO2 capture (second cycle). This process was repeated 50 times. Specific test results are as follows: Figure 5 As shown.

[0128] like Figure 5As shown, different Cu contents have a significant impact on the cyclic CO2 capture performance of Cu-Mg-Ca ternary metal bifunctional materials. Materials with low Cu loading, especially bifunctional material-I (Cu0.1Mg10CaO bifunctional material), actually have better cyclic carbon capture performance than the Cu-free control material Mg10CaO in the cycle.

[0129] Other Tests

[0130] The distribution of Cu and the CaO lattice in bifunctional material-I (Cu0.1Mg10CaO bifunctional material) were analyzed using aberration-corrected transmission electron microscopy. The results are as follows: Figure 6 As shown. Figure 6 As shown, Cu metal exists in the bifunctional material-I (Cu0.1Mg10CaO bifunctional material) in the form of single atoms. Through the strong interaction between the metal and the support, Cu single atoms not only have good cyclic reaction activity in the reaction, but can also exist in the bifunctional material in the form of single atoms at a certain temperature.

Claims

1. A Cu-Mg-Ca ternary metal bifunctional material, characterized in that, The bifunctional material composition contains Cu element, Mg element and Ca element, wherein, The atomic ratio of Cu element to all metal elements is 0.1%-1%, The atomic ratio of Mg element to all metal elements is 5%-15%, The Cu element exists in the form of Cu metal, the Mg element exists in the form of MgO, and the Ca element exists in the form of CaO.

2. The method for preparing the Cu-Mg-Ca ternary metal bifunctional material according to claim 1, characterized in that, The preparation method comprises the following steps: S1: adding a precursor of Cu, a precursor of Mg and a precursor of Ca into deionized water according to the atomic ratio of claim 1, stirring to completely dissolve, and obtaining a solution; S2: adding citric acid to the above solution and stirring; S3: stirring and heating the solution obtained in S2 until a wet gel is obtained; S4: drying and aging the wet gel to obtain a dry gel; S5: calcining the dry gel at a heating rate of 60-100℃ / min to 800-850℃ for 2-4h, rapidly cooling at a cooling rate of 60-100℃ / min, and obtaining a Cu-Mg-Ca bifunctional material powder; S6: granulating the Cu-Mg-Ca bifunctional material powder to obtain a Cu-Mg-Ca ternary metal bifunctional material.

3. The preparation method according to claim 2, characterized in that, The precursor of Cu in step S1 is copper nitrate, the precursor of Mg is magnesium nitrate, and the precursor of Ca is calcium nitrate.

4. The production method according to claim 2 or 3, characterized by, In step S2, the ratio of the sum of the moles of Cu element, Mg element and Ca element metal ions to the mole amount of citric acid is 1:1-1:1.

5.

5. The method of any one of claims 2-4, wherein, In step S3, the stirring speed is 200-300rmp, the stirring and heating is oil bath heating, the oil bath heating temperature is 85-95℃, and the heating time is 8-12 hours.

6. The method of any one of claims 2-5, wherein, In step S4, the drying and aging temperature is 110-140℃, and the drying and aging time is 8-14 hours.

7. The method of any one of claims 2-6, wherein, In step S6, the granulation is carried out by using a hydraulic granulator, the processing pressure is 9-11MPa, and the particle size of the bifunctional material is 40-60 mesh.

8. A method of CO2 capture and in-situ utilization, characterized by, The method comprises the following steps: Step one: weighing the Cu-Mg-Ca ternary metal bifunctional material of claim 1 and placing it into a reactor; Step two: heating the reactor, introducing flue gas with a CO2 concentration of 10%-17% into the reactor for CO2 capture, and stopping the aeration after the capture is completed; Step three: maintaining the temperature of the reactor in step two, and adding hydrogen to the reactor to produce CO in situ.

9. The CO2 capture and utilization in situ process of claim 8, wherein, In step two, the temperature of the reactor is set to 620-650℃, and the CO2 introduction time is 20-60 minutes.

10. The CO2 capture and utilization in situ process according to claim 8 or 9, characterized in that, In step three, the concentration of H2 is 10%-100%, the H2 introduction time is 20-60 minutes, or no more CO is generated.

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