Method for realizing CO2 capture and methane dry reforming through M2O2CO3-M2O3 circulation

Abstract

The invention belongs to the field of catalysts, and relates to a method for realizing CO2 capture and methane dry reforming through M2O2CO3-M2O3 circulation. The method comprises the following steps: filling a reactor with an anti-carbon deposition type M ' / M2O2CO3-based active material, and activating the anti-carbon deposition type M' / M2O2CO3-based active material; methane or methane-containing mixed gas is introduced into the reactor, the activated M ' / M2O2CO3-based active material reacts with methane at a medium temperature to obtain carbon monoxide and hydrogen, and meanwhile, the M' / M2O2CO3-based active material is converted into M ' / M2O3; and introducing carbon dioxide or a mixed gas containing carbon dioxide into the reactor, and reacting the M ' / M2O3 with the carbon dioxide to generate the anti-carbon deposition type M' / M2O2CO3-based active material so as to realize the recovery of the active material. The layered anti-carbon deposition type M ' / M2O2CO3 material with high CO2 activity is used for loading Ni or Co-based active components to carry out CO2 absorption-methane dry reforming chemical chain reaction, so that the low-temperature reaction activity can be improved, carbon deposition is avoided, and gas separation is not needed.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts and relates to a method for realizing CO2 capture and dry reforming of methane through the M2O2CO3-M2O3 cycle. Background Art

[0002] The basic carrier materials loaded with metal active phases are crucial for the efficient dispersion of the active phases and the absorption and conversion of CO2. Currently, commonly used basic carrier materials include calcium oxide, magnesium oxide, sodium oxide, potassium oxide, lithium zirconate, etc. However, after these carrier materials absorb CO2, carbonates are obtained, and the combination of carbonate ions and metal cations is too firm, requiring a relatively high temperature (>800 °C) to decompose and release CO2 or to react significantly with CH4. In addition, Ni or Co-based active materials are prone to carbon deposition and deactivation during the dry reforming of methane, and the reaction between carbonate materials and carbon usually also requires a relatively high temperature (>800 °C). Summary of the Invention

[0003] Therefore, aiming at the problems that the Ni or Co-based active materials supported by the existing basic carriers have low reactivity and are prone to carbon deposition and deactivation in the chemical looping reaction of CO2 capture-dry reforming of methane (CO2 + CH4 = 2CO + 2H2) at medium temperature (<800 °C), the present invention provides a method for realizing CO2 capture and dry reforming of methane through the M2O2CO3-M2O3 cycle. The Ni or Co-based active components are loaded on the high-CO2-reactivity layered anti-carbon deposition type M’ / M2O2CO3 material for the CO2 absorption-dry reforming of methane chemical looping reaction, which can improve the low-temperature reaction activity, avoid carbon deposition, and eliminate the need for gas separation.

[0004] In the first aspect, the present invention provides a method for the chemical looping reaction of carbon dioxide absorption-dry reforming of methane through the M2O2CO3-M2O3 cycle. The method includes: Step (1): Loading the anti-carbon deposition type M’ / M2O2CO3 active material into a reactor and activating the anti-carbon deposition type M’ / M2O2CO3 active material; Step (2): Introducing methane or a methane-containing mixed gas into the reactor. The activated M’ / M2O2CO3 active material reacts with methane at medium temperature to obtain carbon monoxide and hydrogen, and at the same time, the M’ / M2O2CO3 active material is transformed into M’ / M2O3; Step (3): Introducing carbon dioxide or a carbon dioxide-containing mixed gas into the reactor. M’ / M2O3 reacts with carbon dioxide to generate the anti-carbon deposition type M’ / M2O2CO3 active material, thereby realizing the recovery of the active material.

[0005] Preferably, the anti-coking M’ / M2O2CO3 active material includes an M2O2CO3 support with a layered structure and a metal M’ uniformly distributed on the surface of the M2O2CO3 support. The metal M is one of lanthanum, bismuth, cerium, praseodymium, neodymium, samarium, calcium, and strontium, and the metal M’ is one of nickel, cobalt, ruthenium, and rhodium. The mass ratio of the metal M’ in the anti-coking M’ / M2O2CO3 active material is 3% to 5%.

[0006] Preferably, the anti-coking M’ / M2O2CO3 active material includes an alumina support modified by M2O2CO3 with a layered structure and a metal M’ uniformly distributed on the surface of the M2O2CO3-modified alumina support. The metal M is one of lanthanum, bismuth, cerium, praseodymium, neodymium, samarium, calcium, and strontium, and the metal M’ is one of nickel, cobalt, ruthenium, and rhodium. The mass ratio of the metal M’ in the anti-coking M’ / M2O2CO3 active material is 3% to 5%, and the mass ratio of alumina in the anti-coking M’ / M2O2CO3 active material is 5% to 25%.

[0007] Preferably, in step (1), the activation atmosphere is a mixed gas of hydrogen and nitrogen, the activation temperature is 400 to 800 °C, and the activation time is 0.5 to 5 hours; preferably, the volume percentage of hydrogen in the mixed gas is 1% to 20%.

[0008] Preferably, in step (2), the medium temperature is 600 to 800 °C, and the reaction time is 1 to 10 minutes.

[0009] Preferably, in steps (2) and (3), the reaction space velocity is independently 2000 to 20000 mL / g / h, and the reaction pressure is independently 1 to 3 atm.

[0010] Preferably, in step (3), no reaction occurs in which carbon dioxide and carbon form carbon monoxide.

[0011] Preferably, the method for preparing the anti-coking M’ / M2O2CO3 active material includes: mixing a precursor solution of metal M’, a precursor solution of metal M, and a precipitant solution at room temperature, reacting at room temperature to generate a precipitate, separating and collecting the precipitate, drying to obtain a dried product, and then calcining the obtained dried product to obtain the anti-coking M’ / M2O2CO3 active material; or, the method for preparing the anti-coking M’ / M2O2CO3 active material includes: mixing a precursor solution of metal M’, a precursor solution of metal M, a precipitant solution, and nano-alumina at room temperature, reacting at room temperature to generate a precipitate, separating and collecting the precipitate, drying to obtain a dried product, and then calcining the obtained dried product to obtain the anti-coking M’ / M2O2CO3 active material; preferably, the precursor of metal M is a nitrate of metal M; the precursor of metal M’ is a nitrate of metal M’; the precipitant is a metal carbonate or a metal bicarbonate; preferably, the precipitant is sodium bicarbonate.

[0012] Preferably, the reaction time at room temperature is 0.5 to 5 hours; the calcination temperature is 500 to 700 °C, and the calcination time is 1 to 5 hours.

[0013] In a second aspect, the present invention provides an application of the anti-coking M’ / M2O2CO3 active material in a catalyst for the chemical looping reaction of carbon dioxide absorption-methane dry reforming.

[0014] The present invention has the following beneficial effects:

[0015] 1. The method of the present invention uses the M’ / M2O2CO3 or M’ / M2O2CO3 / Al2O3 (M’ = Ni, Co, Ce, Pr, Nd, Sm, Ca, Sr, M = La, Bi, Ru, Rh) material for the chemical looping reaction of carbon dioxide absorption-methane dry reforming, which can improve the low-temperature reaction activity, avoid coking, and does not require gas separation.

[0016] 2. The equipment of the method of the present invention is simple, easy to operate, has a small investment, and can mass-produce the M’ / M2O2CO3 or M’ / M2O2CO3 / Al2O3 active material. Description of the Drawings

[0017] Figure 1 is the X-ray diffraction pattern of the anti-coking M’ / M2O2CO3 active material in Example 1.

[0018] Figure 2 is the cyclic effect diagram of CO2 capture and methane dry reforming in Example 1.

[0019] Figure 3 is the X-ray diffraction pattern of the anti-coking M’ / M2O2CO3 active material in Example 2.

[0020] Figure 4 It is the cycle effect diagram of CO2 capture and methane dry reforming in Example 2.

[0021] Figure 5 It is the X-ray diffraction pattern of the anti-coking M’ / M2O2CO3 active material in Example 3.

[0022] Figure 6 It is the cycle effect diagram of CO2 capture and methane dry reforming in Example 3.

[0023] Figure 7 It is the X-ray diffraction pattern of the final product M’ / M2O2CO3 active material of the M2O2CO3-M2O3 cycle in Example 4.

[0024] Figure 8 It is the cycle effect diagram of CO2 capture and methane dry reforming in Example 4.

[0025] Figure 9 It is the X-ray diffraction pattern of the final product of the M2O2CO3-M2O3 cycle in Example 5 of the present invention.

[0026] Figure 10 It is the gas concentration curve of CO2 capture and methane dry reforming in Example 5 of the present invention.

[0027] Figure 11 It is the gas concentration curve of CO2 capture and methane dry reforming in Example 6 of the present invention. Detailed implementation manners

[0028] The present invention is further illustrated by the following implementation manners. It should be understood that the following implementation manners are only used to illustrate the present invention and do not limit the present invention.

[0029] The method for carrying out the chemical looping reaction of CO2 absorption-methane dry reforming through the M2O2CO3-M2O3 cycle in the present invention. The method includes: using the anti-coking M’ / M2O2CO3 active material as a catalyst, passing CH4 through the anti-coking M’ / M2O2CO3 active material, reacting at a medium temperature to obtain the products CO + H2, and at the same time the anti-coking M’ / M2O2CO3 active material is transformed into M’ / M2O3; then passing low-concentration CO2 through M’ / M2O3 to react to generate the anti-coking M’ / M2O2CO3 active material, thereby realizing the recovery of the active material.

[0030] The prior art mentions the use of nickel-based catalysts in catalytic carbon dioxide hydrogenation and methanation reactions. The present invention has a completely different application scenario, namely, applying the active material to the reaction of CO2 and CH4 to produce synthesis gas. Moreover, conventional catalytic methods simultaneously introduce CO2 and CH4 into the reactor, and carbon deposits need to be promptly eliminated during the process of preparing synthesis gas through methane dry gas reforming. The present invention uses carbon deposition-resistant M' / M2O2CO3 active materials for the carbon dioxide absorption-methane dry reforming chemical chain reaction, where CH4 and CO2 are introduced sequentially without direct mixing. This allows for the capture and subsequent conversion of low-concentration CO2 and has a good effect in slowing down carbon deposition. The present invention utilizes an alkaline carrier loaded with a metal (such as Ni or Co)-based active component to carry out the CO2 capture-methane dry reforming chemical chain reaction (CO2+CH4=2CO+2H2). This has the advantages of in-situ absorption and conversion of low-concentration CO2, avoids separation of N2, has high reaction activity, and is moderately cost-effective. It is a technical route for in-situ capture and conversion of CO2 with good application prospects.

[0031] Here, the steps of performing the CO 2 absorption-methane dry reforming chemical chain reaction using the M′ / M 2 O 2 CO 3 material are exemplified.

[0032] Step 1: Load the anti-carbon deposition type M' / M2O2CO3 active material into a reactor and activate the anti-carbon deposition type M' / M2O2CO3 active material. The reactor includes but is not limited to a fixed bed reactor.

[0033] Step 2 (the first stage of the chemical chain reaction): CH4 or a mixed gas containing CH4 is passed through the active material M' / M2O2CO3 to produce the target product CO+H2, and the active material is converted to M' / M2O3. The volume percentage of CH4 in the mixed gas containing CH4 can be 5-15%.

[0034] Step 3 (second stage of chemical chain reaction): Low concentration CO2 or mixed gas containing CO2 is passed through M' / M2O3 to obtain M' / M2O2CO3, and the active material is restored. The volume percentage of CO2 in the mixed gas containing CO2 can be 5-15%.

[0035] The reaction mechanism of the present invention: M2O2CO3 is a layered structure, (M2O2) 2+ Layer with CO3 2- The layers are arranged alternately, and in the first stage of the chemical chain reaction, CO3 2- The layer easily reacts with CH4 under the promotion of active metal M, or CO3 2- The layer reacts with the CH4 cracking product C to produce CO+H2, and itself becomes O 2-(M2O2CO3 is converted to M2O3). In the second stage of the chemical looping reaction, low-concentration CO2 is absorbed using the basicity of M2O3 to restore M2O2CO3. By controlling the material preparation and chemical reaction conditions and utilizing the reaction characteristics of M2O2CO3 with carbon, carbon deposition can be eliminated, thereby ensuring that CO is not produced in the second stage of the chemical looping reaction (CO2 + C = 2CO), thus avoiding the gas separation process.

[0036] In some embodiments, the medium temperature is 600 - 800 °C (e.g., 700 °C), and the reaction time is 1 - 10 minutes.

[0037] In some embodiments, the reaction space velocity is 2000 - 20000 mL / g / h, and the reaction pressure is 1 - 3 atm.

[0038] In some embodiments, the anti-carbon deposition type M’ / M2O2CO3 active material includes a layered M2O2CO3 support and a metal M’ uniformly distributed on the surface of the M2O2CO3 support. Since the M2O2CO3 material has a layered structure, the CO3 2- layer can react with methane at a medium temperature. In some embodiments, the metal M is one of lanthanum (La), bismuth (Bi), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), calcium (Ca), strontium (Sr); the metal M’ is one of nickel (Ni), cobalt (Co), ruthenium (Ru), rhodium (Rh).

[0039] Among them, the mass ratio of the metal M’ in the anti-carbon deposition type M’ / M2O2CO3 active material is 3% - 5%. If there is too much M’, it is easy to deactivate due to carbon deposition; if there is too little M’, the activity is insufficient. Experiments have found that if the content of M’ is too high, it will cause insufficient content of M2O2CO3, or the time for introducing CH4 into the reactor is too long. At this time, carbon deposition is likely to occur, and the purpose of eliminating carbon deposition cannot be achieved.

[0040] In some embodiments, the anti-carbon deposition type M’ / M2O2CO3 active material includes a layered M2O2CO3-modified alumina support and a metal M’ uniformly distributed on the surface of the M2O2CO3-modified alumina support. Alumina is a porous support with a high specific surface area. In the M2O2CO3-modified alumina support, M2O2CO3 is coated on the surface of alumina. The introduction of alumina can improve the stability of the reaction activity of the material.

[0041] Among them, the mass ratio of the metal M' in the anti-coking M' / M₂O₂CO₃ active material is 3% - 5%, and the mass ratio of the alumina in the anti-coking M' / M₂O₂CO₃ active material is 5% - 25%. If the amount of alumina is too small, it is not conducive to the dispersion of M₂O₂CO₃ and the stability of the reaction activity of the material. If the amount of alumina is too large, it will react with the oxide of metal M (such as M₂O₃ like La₂O₃) to obtain a stable compound, consuming the oxide of metal M and thus reducing the reaction activity. Experiments have found that if the content of Al₂O₃ is too high, it will cause insufficient content of M₂O₂CO₃, or the time for introducing CH₄ into the reactor is too long. At this time, carbon deposition is likely to occur and the purpose of carbon deposition elimination cannot be achieved.

[0042] As an example, the preparation method of the anti-coking M' / M₂O₂CO₃ active material includes: mixing the precursor solution of metal M', the precursor solution of metal M, and a precipitant solution containing carbonate (or bicarbonate) at room temperature, reacting to produce a precipitate, separating, collecting the precipitate, drying to obtain a dried product, and then calcining the obtained dried product to obtain the anti-coking M' / M₂O₂CO₃ active material. The precursor of metal M is nitrate of metal M. The precursor of metal M' can be nitrate of metal M'. The concentration of the precursor solution of metal M' can be 0.01 - 0.2 mol / mL, preferably 0.01 - 0.1 mol / mL. The concentration of the precursor solution of metal M can be 0.01 - 1 mol / mL, preferably 0.05 - 0.5 mol / mL. The precipitant can be sodium bicarbonate. The concentration of the precipitant solution can be 0.5 - 2 mol / mL.

[0043] Or, as an example, the preparation method of the anti-coking M' / M₂O₂CO₃ active material includes: mixing the precursor solution of metal M', the precursor solution of metal M, a precipitant solution containing carbonate (or bicarbonate), and nano-alumina at room temperature, reacting to produce a precipitate, separating, collecting the precipitate, drying to obtain a dried product, and then calcining the obtained dried product to obtain the anti-coking M' / M₂O₂CO₃ active material. The concentration of the precursor solution of metal M' can be 0.01 - 0.2 mol / mL, preferably 0.01 - 0.1 mol / mL. The concentration of the precursor solution of metal M can be 0.01 - 1 mol / mL, preferably 0.05 - 0.5 mol / mL. The precipitant can be sodium bicarbonate. The concentration of the precipitant solution can be 0.5 - 2 mol / mL.

[0044] In the preparation method, the reaction temperature is room temperature, and the reaction time is 0.5 - 5 hours. Also, the calcination temperature is 500 - 700 °C, and the calcination time is 1 - 5 hours.

[0045] For example, at room temperature, the precursor solution A of metal M' (such as nickel / cobalt), the precursor solution B of metal M (such as lanthanum / bismuth), and the precipitant solution C containing bicarbonate are rapidly mixed to cause a reaction to produce a precipitate. After filtration and drying, a dried product is obtained. The dried product is calcined at 500 - 700 °C for 1 - 5 hours to obtain the target active material M' / M2O2CO3 (M' = Ni or Co, M = La or Bi).

[0046] The present invention also provides the application of the anti-coking M' / M2O2CO3 active material in a catalyst support for the chemical looping reaction of CO2 absorption - dry reforming of methane.

[0047] In summary, to solve the problems of low activity at medium temperature and easy coking and deactivation caused by the formation of carbonates after the absorption of CO2 by the basic support material in the existing active material system, the present invention proposes a method for efficiently realizing the chemical looping reaction of low-concentration CO2 capture - dry reforming of methane at medium temperature through the M2O2CO3 - M2O3 cycle. The materials M' / M2O2CO3 or M' / M2O2CO3 / Al2O3 (M' = Ni, Co, Ce, Pr, Nd, Sm, Ca, Sr, M = La, Bi, Ru, Rh) are used for the chemical looping reaction of CO2 absorption - dry reforming of methane, which can improve the low-temperature reaction activity, avoid carbon deposition, and eliminate the need for gas separation.

[0048] The following further lists examples to illustrate the present invention in detail. It should be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description herein, rather than being limited to the specific values in the following examples.

[0049] Example 1

[0050] An anti-coking M' / M2O2CO3 active material and its application in the chemical looping reaction of CO2 absorption - dry reforming of methane. The steps are as follows:

[0051] Step 1: Dissolve 7.5 mmol of lanthanum nitrate and 1.25 mmol of nickel nitrate in 60 mL of water to obtain solution A. Dissolve 60 mmol of sodium bicarbonate in 60 mL of water to obtain solution B.

[0052] Step 2: Under stirring conditions, rapidly pour solution B into solution A (the addition rate is 1800 mL / min), and react at room temperature for 30 minutes.

[0053] Step 3: After centrifugally collecting the precipitate, wash it 3 times by centrifugal water washing, and then fully dry it in air at 80 °C.

[0054] Step 4: Calcinate the powder obtained after drying in static air at 700 °C for 3 h to obtain the final product, named 5 wt% Ni-La2O2CO3. Among them, the theoretical mass ratio of Ni to La2O2CO3 is 5:95.

[0055] Step 5: Load 1.0 g of the sample obtained in Step 4 into a quartz tube reactor with an inner diameter of φ12 mm, and reduce it at 700 °C for 2 h in H2 / N2 (10% / 90%) under atmospheric pressure for activation. Then introduce CH4 / N2 (5% / 95%) for reaction testing, and then introduce CO2 / N2 (15% / 85%). The catalyst carrier reacts to form lanthanum oxycarbonate, the reaction space velocity is 6000 ml / g / h, and the reaction pressure is 1 atm. After the reaction proceeds stably, the composition of the tail gas is analyzed by on-line sampling with a flue gas analyzer.

[0056] Figure 1 This is the X-ray diffraction pattern of the sample obtained in Step 4 of Example 1 of the present invention. It can be seen that the product has good crystallization, and the main phase is La2O2CO3.

[0057] Figure 2 This is the reaction result obtained in Step 5 of Example 1 of the present invention. It can be seen that after 30 cycles, the methane conversion rate can be maintained above 80%, and H2 / CO is stable at around 0.9 throughout the cycle. Methane conversion rate = 100% * [amount of methane introduced into the reactor - amount of methane flowing out of the reactor] / amount of methane introduced into the reactor. H2 / CO = amount of H2 flowing out of the reactor / amount of CO flowing out of the reactor.

[0058] Example 2

[0059] Step 1: Dissolve 13.5 mmol of lanthanum nitrate and 2.25 mmol of nickel nitrate in 60 mL of water, and add 2.45 mmol of nano-aluminum oxide, and disperse evenly to obtain Solution A. Dissolve 108 mmol of sodium bicarbonate in 120 mL of water to obtain Solution B.

[0060] Step 2: Under stirring conditions, quickly pour Solution B into Solution A (the addition speed is 1800 mL / min), and react at room temperature for 30 minutes.

[0061] Step 3: After centrifugally collecting the precipitate, wash it 3 times by centrifugal water washing, and then fully dry it in air at 80 °C.

[0062] Step 4: The powder obtained after drying is calcined in static air at 700 °C for 3 h to obtain the final product, named Ni / La2O2CO3 / Al2O3. Among them, the theoretical mass ratio of Ni / La2O2CO3 / Al2O3 is 4.6:86.7:8.7.

[0063] Step 5: 1.0 g of the sample obtained in Step 4 is loaded into a quartz tube reactor with an inner diameter of φ12 mm and reduced at 700 °C for 2 h in H2 / N2 (10% / 90%) under atmospheric pressure for activation. Subsequently, CH4 / N2 (5% / 95%) is introduced for reaction testing, and then CO2 / N2 (15% / 85%) is introduced to react with the catalyst support to form lanthanum oxycarbonate. The reaction space velocity is 6000 ml / g / h, and the reaction pressure is 1 atm. After the reaction proceeds stably, the composition of the tail gas is analyzed by on-line sampling with a flue gas analyzer.

[0064] Figure 3 This is the X-ray diffraction pattern of the sample obtained in Step 4 of Example 2 of the present invention. It can be seen that the product has good crystallization, and the main phase is La2O2CO3.

[0065] Figure 4 This is the reaction result obtained in Step 5 of Example 2 of the present invention. It can be seen that after 30 cycles, the methane conversion rate can be maintained above 85%, and H2 / CO remains stable after 10 cycles and is close to 1.0.

[0066] Example 3

[0067] Step 1: 11.25 mmol of lanthanum nitrate and 1.87 mmol of nickel nitrate are dissolved in 60 mL of water, and 6.79 mmol of nano-alumina is added and dispersed evenly to obtain Solution A. 90 mmol of sodium bicarbonate is dissolved in 90 mL of water to obtain Solution B.

[0068] Step 2: Under stirring conditions, Solution B is quickly poured into Solution A (the addition rate is 1800 mL / min), and the reaction is carried out at room temperature for 30 minutes.

[0069] Step 3: After the precipitate is collected by centrifugation, it is washed 3 times by centrifugal washing with water, and then dried thoroughly in air at 80 °C.

[0070] Step 4: The powder obtained after drying is calcined in static air at 700 °C for 3 h to obtain the final product, named Ni / La2O2CO3 / Al2O3. Among them, the theoretical mass ratio of Ni / La2O2CO3 / Al2O3 is 3.8:72.2:24.0.

[0071] Step 5: Load 1.0 g of the sample obtained in Step 4 into a quartz tube reactor with an inner diameter of φ12 mm, and reduce it at 700 °C for 2 hours in H2 / N2 (10% / 90%) under atmospheric pressure for activation. Subsequently, introduce CH4 / N2 (5% / 95%) for reaction testing, and then introduce CO2 / N2 (15% / 85%) to react with the catalyst support to form lanthanum oxycarbonate. The reaction space velocity is 6000 ml / g / h, and the reaction pressure is 1 atm. After the reaction proceeds stably, the composition of the tail gas is analyzed by on-line sampling with a flue gas analyzer.

[0072] Figure 5 This is the X-ray diffraction pattern of the sample obtained in Step 4 of Example 3 of the present invention. It can be seen that the product has good crystallization, and the main phase is La2O2CO3.

[0073] Figure 6 This is the reaction result obtained in Step 5 of Example 3 of the present invention. It can be seen that after 30 cycles, the methane conversion rate can be maintained above 80%, and H2 / CO is stable at 1.0 - 1.1 throughout the cycle. The support Al2O3 has a large specific surface area and high stability, especially higher thermal stability after contacting with La. Therefore, compared with Example 1, the reaction stability in Examples 2 - 3 is improved.

[0074] Example 4

[0075] Step 1: Dissolve 12.87 mmol of lanthanum nitrate and 1.28 mmol of nickel nitrate in 60 mL of water, disperse evenly to obtain Solution A. Dissolve 120 mmol of sodium bicarbonate in 120 mL of water to obtain Solution B.

[0076] Step 2: Under stirring conditions, quickly pour Solution B into Solution A (the addition rate is 1800 mL / min), and react at room temperature for 30 minutes.

[0077] Step 3: After centrifugally collecting the precipitate, wash it 3 times by centrifugal washing, and then dry it thoroughly in air at 80 °C.

[0078] Step 4: Calcinate the powder obtained after drying in static air at 700 °C for 3 h to obtain the final product, named Ni / La2O2CO3. Among them, the theoretical mass ratio of Ni / La2O2CO3 is 3.1:96.9.

[0079] Step 5: Load 1.0 g of the sample obtained in Step 4 into a quartz tube reactor with an inner diameter of φ12 mm, and reduce it at 700 °C for 2 hours in H2 / N2 (10% / 90%) under atmospheric pressure for activation. Subsequently, introduce CH4 / N2 (5% / 95%) for reaction testing, and then introduce CO2 / N2 (15% / 85%) to react with the catalyst support to form lanthanum oxycarbonate. The reaction space velocity is 6000 ml / g / h, and the reaction pressure is 1 atm. After the reaction proceeds stably, the composition of the tail gas is analyzed by on-line sampling with a flue gas analyzer.

[0080] Figure 7 This is the X-ray diffraction pattern of the sample obtained in Step 5 of Example 4 of the present invention. It can be seen that the sample after the reaction remains well-crystallized, and the main phase is still La2O2CO3.

[0081] Figure 8 This is the reaction result obtained in Step 5 of Example 4 of the present invention. It can be seen that H2 / CO in the entire cycle (CH4 reaction stage + CO2 reaction stage) stabilizes around 0.8 after 4 cycles, and is very close to H2 / CO in the CH4 reaction stage, indicating that there is almost no carbon deposition residue in the CH4 reaction stage. Therefore, almost no CO is produced in the CO2 reaction stage, and thus there is no need to separate and obtain CO.

[0082] Example 5

[0083] Step 1: Dissolve 18.75 mmol of lanthanum nitrate and 3.12 mmol of nickel nitrate in 60 mL of water, and add 34.02 mmol of nano-aluminum oxide, and disperse evenly to obtain Solution A. Dissolve 150 mmol of sodium bicarbonate in 150 mL of water to obtain Solution B.

[0084] Step 2: Under stirring conditions, quickly pour Solution B into Solution A (the addition rate is 1800 mL / min), and react at room temperature for 30 minutes.

[0085] Step 3: Centrifuge and collect the precipitate, wash it 3 times by centrifugal washing, and then dry it thoroughly in air at 100 °C.

[0086] Step 4: Calcinate the powder obtained after drying in static air at 700 °C for 3 h to obtain the final product, named Ni / La2O2CO3 / Al2O3. Among them, the theoretical mass ratio of Ni / La2O2CO3 / Al2O3 is 2.6:48.7:48.7.

[0087] Step 5: Load 1.0 g of the sample obtained in Step 4 into a quartz tube reactor with an inner diameter of φ12 mm, and reduce it at 700 °C for 2 hours in H2 / N2 (10% / 90%) under atmospheric pressure for activation. Subsequently, introduce CH4 / N2 (5% / 95%) for reaction testing, and then introduce CO2 / N2 (15% / 85%) to react with the catalyst support to form lanthanum oxycarbonate. The reaction space velocity is 6000 ml / g / h, and the reaction pressure is 1 atm. After the reaction proceeds stably, the composition of the tail gas is analyzed by on-line sampling with a flue gas analyzer.

[0088] Figure 9 This is the X-ray diffraction pattern of the sample obtained in Step 5 of Example 5 of the present invention. It can be seen that the sample after the reaction remains well-crystallized, and the main phase is still La2O2CO3. However, due to the presence of a large amount of Al2O3, an obvious LaAlO3 phase appears. Therefore, too high an Al2O3 content will capture La and lead to insufficient La2O2CO3.

[0089] Figure 10 This is the reaction result obtained in Step 5 of Example 5 of the present invention. It can be seen that less CO is generated during the CH4 introduction stage, and significantly more CO is generated during the CO2 introduction stage (CO2 + C = 2CO), which indicates that a large amount of carbon deposition occurs during the CH4 introduction stage. Thus, it can be seen that too high an Al2O3 content will lead to insufficient La2O2CO3 and then carbon deposition.

[0090] Example 6

[0091] Step 1: Dissolve 12.85 mmol of lanthanum nitrate and 4.5 mmol of nickel nitrate in 60 mL of water, disperse evenly to obtain Solution A. Dissolve 120 mmol of sodium bicarbonate in 120 mL of water to obtain Solution B.

[0092] Step 2: Under stirring conditions, quickly pour Solution B into Solution A (the addition rate is 1800 mL / min), and react at room temperature for 30 minutes.

[0093] Step 3: After centrifugally collecting the precipitate, wash it 3 times by centrifugal washing with water, and then dry it thoroughly in air at 80 °C.

[0094] Step 4: Calcinate the powder obtained after drying in static air at 700 °C for 3 h to obtain the final product, named Ni / La2O2CO3. Among them, the theoretical mass ratio of Ni / La2O2CO3 is 10:90.

[0095] Step 5: Load 1.0 g of the sample obtained in Step 4 into a quartz tube reactor with an inner diameter of φ12 mm, and reduce it at 700 °C for 2 hours in H2 / N2 (10% / 90%) under atmospheric pressure for activation. Subsequently, introduce CH4 / N2 (5% / 95%) for reaction testing, and then introduce CO2 / N2 (15% / 85%) to react with the catalyst support to form lanthanum oxycarbonate. The reaction space velocity is 6000 ml / g / h, and the reaction pressure is 1 atm. After the reaction proceeds stably, the composition of the tail gas is analyzed by on-line sampling with a flue gas analyzer.

[0096] Figure 11 This is the reaction result obtained in Step 5 of Example 6 of the present invention. It can be seen that less CO is generated during the stage of introducing CH4, and more CO is generated during the stage of introducing CO2 (CO2 + C = 2CO), which indicates that a large amount of carbon deposition is generated during the stage of introducing CH4. Thus, it can be seen that too high a Ni content will cause the CH4 to decompose too fast and generate carbon deposition.

Claims

1. A method for chemical looping reaction of carbon dioxide absorption - methane dry reforming through the M2O2CO3 - M2O3 cycle, characterized in that, The method includes: Step (1): Loading the anti-coking M’ / M2O2CO3-based active material into a reactor, and activating the anti-coking M’ / M2O2CO3-based active material; Step (2): Introducing methane or a methane-containing mixed gas into the reactor. The activated M’ / M2O2CO3-based active material reacts with methane at a moderate temperature to obtain carbon monoxide and hydrogen, and meanwhile, the M’ / M2O2CO3-based active material is transformed into M’ / M2O3; Step (3): Introducing carbon dioxide or a carbon dioxide-containing mixed gas into the reactor. M’ / M2O3 reacts with carbon dioxide to generate the anti-coking M’ / M2O2CO3-based active material, thereby realizing the recovery of the active material.

2. The method according to claim 1, wherein, The anti-coking M’ / M2O2CO3-based active material includes a layered M2O2CO3 support and metal M’ uniformly distributed on the surface of the M2O2CO3 support. The metal M is one of lanthanum, bismuth, cerium, praseodymium, neodymium, samarium, calcium, and strontium. The metal M’ is one of nickel, cobalt, ruthenium, and rhodium. The mass ratio of the metal M’ in the anti-coking M’ / M2O2CO3-based active material is 3% - 5%.

3. The method according to claim 1, wherein The anti-coking M’ / M2O2CO3-based active material includes a layered alumina support modified by M2O2CO3 and metal M’ uniformly distributed on the surface of the M2O2CO3-modified alumina support. The metal M is one of lanthanum, bismuth, cerium, praseodymium, neodymium, samarium, calcium, and strontium. The metal M’ is one of nickel, cobalt, ruthenium, and rhodium. The mass ratio of the metal M’ in the anti-coking M’ / M2O2CO3-based active material is 3% - 5%. The mass ratio of alumina in the anti-coking M’ / M2O2CO3-based active material is 5% - 25%.

4. The method according to any one of claims 1 to 3, characterized in that, In step (1), the activation atmosphere is a mixed gas of hydrogen and nitrogen, the activation temperature is 400 - 800 °C, and the activation time is 0.5 - 5 hours. Preferably, the volume percentage of hydrogen in the mixed gas is 1% - 20%.

5. The method according to any one of claims 1 to 4, characterized in that, In step (2), the moderate temperature is 600 - 800 °C, and the reaction time is 1 - 10 minutes.

6. The method according to any one of claims 1 to 5, characterized in that In steps (2) and (3), the reaction space velocity is independently 2000 - 20000 mL / g / h, and the reaction pressure is independently 1 - 3 atm.

7. The method according to any one of claims 1 to 6, characterized in that, In step (3), the reaction of carbon dioxide and carbon to generate carbon monoxide does not occur.

8. The method according to any one of claims 1 to 7, characterized in that The preparation method of the anti-coking M’ / M2O2CO3-based active material includes: mixing a precursor solution of metal M’, a precursor solution of metal M, and a precipitant solution at room temperature, reacting at room temperature to generate a precipitate, separating and collecting the precipitate, drying to obtain a dried product, and then calcining the obtained dried product to obtain the anti-coking M’ / M2O2CO3-based active material; alternatively, the preparation method of the anti-coking M’ / M2O2CO3-based active material includes: mixing a precursor solution of metal M’, a precursor solution of metal M, a precipitant solution, and nano-alumina at room temperature, reacting at room temperature to generate a precipitate, separating and collecting the precipitate, drying to obtain a dried product, and then calcining the obtained dried product to obtain the anti-coking M’ / M2O2CO3-based active material; preferably, the precursor of metal M is a nitrate of metal M; the precursor of metal M’ is a nitrate of metal M’; the precipitant is a metal carbonate or a metal bicarbonate; preferably, the precipitant is sodium bicarbonate.

9. The method according to claim 8, wherein The reaction time at room temperature is 0.5 to 5 hours; the calcination temperature is 500 to 700 °C, and the calcination time is 1 to 5 hours.

10. Application of an anti-coking M’ / M2O2CO3-based active material in a catalyst for a chemical looping reaction of carbon dioxide absorption-methane dry reforming.

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