Multi-metal layered hydroxide catalytic material as well as preparation method and application thereof

Abstract

The invention discloses a multi-metal layered hydroxide catalytic material and a preparation method and application thereof, and belongs to the technical field of catalytic materials.The preparation method of the multi-metal layered hydroxide catalytic material comprises the following steps that a one-pot solvothermal method is adopted, foamed nickel is soaked in a mixed solution for hydro-thermal synthesis, and the multi-metal layered hydroxide catalytic material is obtained; the multi-metal layered hydroxide catalytic material is prepared; wherein the mixed solution comprises a surfactant, a solvent and at least two of a nickel source, an iron source and a cobalt source. The CO2 desorption rate of the MEA solution is jointly improved through the synergistic effect of multiple metals and the # imgabs0 # acid site provided by the periphery of the metal hydroxide main layer. Under the condition that the desorption temperature (oil bath pan temperature) is 120 DEG C, the highest CO2 desorption rate of the FeCo (1 / 5) material with the best catalytic effect is increased to 7.68 mmol / min, and compared with 4.78 mmol / min under the blank condition, the desorption rate of the FeCo (1 / 5) material is increased by 60.7%, and the CO2 desorption rate is remarkably increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic materials, and particularly relates to a multi-metal layered hydroxide catalytic material, a preparation method thereof, and an application thereof. Background Art

[0002] In the past nearly a century, with the development of the economic society and the improvement of productivity, fossil fuels have been extensively developed. The combustion of fossil fuels has generated a large amount of CO2 gas, which has gradually increased the content of CO2 gas in the atmosphere. As a major greenhouse gas in the atmosphere, the increase in its content has caused the greenhouse effect, seriously affecting the stability of the global ecosystem and the survival and development of humans and other organisms.

[0003] Carbon dioxide capture, utilization, and storage (CCUS) technology is an important technology for reducing CO2 emissions and solving the problem of global warming. Among them, carbon capture technology can be divided into three approaches: pre-combustion capture, post-combustion capture, and oxy-fuel combustion. Post-combustion capture methods usually include chemical absorption (such as amine absorption), solid adsorbents (such as N-functionalized sliding adsorbents (NFSA)), and physical separation methods (such as membrane separation) to separate CO2. Among these methods, the amine solution chemical absorption post-combustion carbon capture method is one of the technologies with the largest scale and the most extensive commercial application at present. Ethanolamine (MEA) has become the standard amine for amine chemical absorption methods due to its advantages such as large CO2 absorption capacity, fast absorption rate, and high absorption efficiency. However, the traditional MEA chemical absorption method still has problems such as slow CO2 desorption rate, high solvent regeneration temperature (exceeding 120 °C), strong regeneration heat load, and easy corrosion of equipment. According to the literature, due to the extremely large regeneration heat load generated during the regeneration process of the MEA solution, the energy consumption during the regeneration process accounts for more than two-thirds of the entire operating cost, which seriously hinders the large-scale industrial application of the amine solution chemical absorption method. Therefore, it is necessary to develop a new technology to solve the problems of slow CO2 desorption rate, high solvent regeneration temperature, and strong regeneration heat load.

[0004] The MEA regeneration process mainly includes the decomposition of carbamate (MEACOO - ) and the deprotonation of protonated amine (MEAH + ). The decomposition of MEACOO - is an endothermic reaction and requires acidic protons as reactants. The deprotonation of MEAH + can provide acidic protons for the decomposition of MEACOO - . However, under alkaline conditions, the proton transfer of MEAH + in H2O also consumes a large amount of energy. Therefore, the high heat load of the MEA regeneration process is due to the endothermic reaction of the decomposition of MEACOO - and MEAH under alkaline conditions+ Deprotonation reaction in water. MEAH + The deprotonation of MEAH is the step with the highest Gibbs free energy during the regeneration process and also the rate-limiting step in the regeneration process. Therefore, the key to reducing the regeneration heat load and energy consumption of MEA lies in how to provide a large amount of acidic protons in the reaction.

[0005]

[0006] The surface of solid acid catalysts contains a large number of acidic protons (including Brønsted acids and Lewis acids), so some studies have proposed adding solid acid catalysts during the regeneration of MEA to reduce the regeneration energy consumption of MEA and promote CO2 desorption. Currently, the main solid acid catalysts include zeolite molecular sieves, metal oxides, sulfate metal oxides, composite solid acid catalysts, and metal-organic frameworks (MOFs), etc.; however, the current solid acid catalysts have problems such as poor catalytic performance and unclear desorption mechanism. For example, the surface pores of solid acid catalysts are prone to blockage after multiple cycles of use, resulting in serious deactivation of the catalysts. Some composite solid acid catalysts loaded with metals will leach metal ions after multiple cycles of use, resulting in the loss of active sites, and the leached ions will also accelerate the oxidative degradation of the MEA solution, all of which reduce the catalytic activity of the catalysts.

[0007] Therefore, there is an urgent need to provide a catalytic material with high catalytic desorption performance to meet the actual needs of the chemical absorption method of amine solutions in large-scale industrial applications. Summary of the Invention

[0008] In view of the above technical problems, the present invention proposes a multi-metal layered hydroxide catalytic material, its preparation method and application. An efficient catalyst with excellent catalytic desorption performance, high temperature resistance, and strong alkali resistance is synthesized by a simple one-pot solvothermal method, fundamentally solving the problem of excessive energy consumption in the chemical absorption method of amine solutions to meet the actual needs of large-scale industrial applications.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] One of the technical solutions of the present invention:

[0011] A preparation method of a multi-metal layered hydroxide catalytic material, comprising the following steps:

[0012] Using a one-pot solvothermal method, soak nickel foam in a mixed solution for hydrothermal synthesis to prepare a multi-metal layered hydroxide catalytic material;

[0013] Wherein, the mixed solution includes a surfactant, a solvent, and at least two of a nickel source, an iron source, and a cobalt source.

[0014] Optionally, the nickel foam is used as a substrate and needs to be pretreated before being immersed in the mixed solution. The specific steps are as follows:

[0015] First, clean the nickel foam. Immerse the nickel foam in a 37 wt% concentrated HCl solution and ultrasonicate for 5 min to remove impurities such as NiO on the surface and perform etching to obtain nickel foam with a larger specific surface area.

[0016] Then, wash it with water and methanol for 5 minutes to remove the HCl on the surface and ensure that the surface of the nickel foam is clean.

[0017] Optionally, the nickel source, iron source, and cobalt source are all soluble metal salts.

[0018] Optionally, the surfactant is CTAB (cetyltrimethylammonium bromide) or octadecyltrimethylammonium chloride (CTAC). The above substances are a kind of common cationic surfactants, which guide the aggregation and precipitation reactions of metal ions in a hot solvent to form nanomaterials with specific morphologies and sizes.

[0019] Furthermore, the molar ratio of the nickel source to the surfactant is 0.9∶1.4; and / or,

[0020] The ratio of the total amount of the iron source and cobalt source to the amount of the surfactant in terms of the amount of substance is 1.2∶1.4.

[0021] Even further, the molar ratio of the iron source to the cobalt source is (1∶5)-(2∶1); preferably 1∶5, 1∶2, 1∶1, 2∶1; more preferably 1∶5.

[0022] Optionally, the solvent is a mixed solution of water and methanol.

[0023] Optionally, the conditions in the hydrothermal synthesis process are as follows:

[0024] Perform hydrothermal synthesis at 180 °C for 12 - 24 h.

[0025] The second technical solution of the present invention:

[0026] A multi-metal layered hydroxide catalytic material is prepared by the above preparation method.

[0027] Optionally, the composition of the multi-metal layered hydroxide catalytic material is Ni x Fe y Co z -LDH;

[0028] wherein, x = 0.9, y + z = 1.2.

[0029] Furthermore, the composition of the multi-metal layered hydroxide catalytic material is Ni 0.9 Fe0.2 Co1-LDH, i.e., FeCo(1 / 5) prepared in Example 3.

[0030] The third technical solution of the present invention:

[0031] Application of the above-mentioned multi-metal layered hydroxide catalytic material in the catalytic desorption of CO2.

[0032] Optionally, during the CO2 catalytic desorption process, the temperature of the oil bath is set to 100 - 130 °C; preferably 100 °C, 110 °C, 120 °C and 130 °C; more preferably 120 °C. Among them, when the temperature of the oil bath is set to 100 °C, 110 °C, 120 °C and 130 °C, the measured temperatures of the desorption reaction solution are 89 °C, 95 °C, 98 °C and 101 °C respectively. When the oil bath is set to 120 °C, the growth rate of the desorption rate is the largest.

[0033] Compared with the prior art, the present invention has the following advantages and technical effects:

[0034] The present invention prepares a catalytic material of nickel foam in-situ grown multi-metal layered hydroxide, in which the metal hydroxide layer has a block structure, and the trivalent or divalent metals on the surface form Lewis acid sites. The hydroxyl groups on the periphery of the main layer of the metal hydroxide can provide acidic protons H + As acid sites, the layered hydroxide catalytic material has a large specific surface area on its surface, increasing the contact area between the active sites and the reactants, and effectively improving the activity of the catalyst. In addition, the metal and the hydroxyl group form a stable six-membered structure, enhancing the stability of the metal sites and improving the high temperature and alkali resistance of the catalyst.

[0035] The present invention improves the CO2 desorption rate of the MEA solution through the synergistic effect of multiple metals and the acid sites provided by the periphery of the main layer of the metal hydroxide. Under the condition that the desorption temperature (oil bath temperature) is 120 °C, the FeCo(1 / 5) material with the best catalytic effect increases the highest CO2 desorption rate to 7.68 mmol / min. Compared with 4.78 mmol / min under the blank condition, this material increases the desorption rate by 60.7%, significantly improving the CO2 desorption rate. Description of the Drawings [[ID=!29]]

[0036] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0037] Figure 1For Comparative Example 1, it is the CO₂ desorption rate graph (a) and the bar graph of the highest CO₂ desorption rate (b) under blank conditions and with the addition of equal volumes of three catalysts, namely FeCo-Ni(1 / 1), Fe-Ni, and Co-Ni;

[0038] Figure 2 For Comparative Example 2, it is the CO₂ desorption rate graph (a) and the bar graph of the maximum CO₂ desorption rate (b) under blank conditions and with the addition of equal masses of FeCo-Ni(1 / 1), Fe-Ni, Co-Ni, and nickel foam;

[0039] Figure 3 For Comparative Example 3, it is the CO₂ desorption rate graph (a) and the bar graph of the maximum CO₂ desorption rate (b) of multi-metal hydroxide catalysts with five different doping ratios;

[0040] Figure 4 For Comparative Example 4, it is the CO₂ desorption rate graph (a) and the bar graph of the maximum CO₂ desorption rate (b) of six multi-metal hydroxide catalysts, namely FeCo-Ni(1 / 1), FeCo / Ni, Co-Ni, Co-Ni / Fe, Fe-Ni, and Fe-Ni / Co;

[0041] Figure 5 For Comparative Example 5, it is the CO₂ desorption rate graph (a) and the bar graph of the maximum CO₂ desorption rate (b) of FeCo-Ni(1 / 5) at four oil bath temperatures of 100 °C, 110 °C, 120 °C, and 130 °C. Detailed Embodiments

[0042] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0043] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0044] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0045] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0046] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0047] An embodiment of this invention discloses a preparation method of a nickel foam in-situ grown multi-metal layered hydroxide catalyst, which includes the following steps:

[0048] First, clean the nickel foam to remove surface impurities. Preferably, soak the nickel foam in a 37 wt% concentrated HCl solution and ultrasonicate for 5 min to remove impurities such as NiO on the surface and perform etching to obtain nickel foam with a larger specific surface area; then wash with water and methanol for 5 minutes to remove the HCl on the surface and ensure the surface of the nickel foam is clean.

[0049] At room temperature, dissolve a nickel source, an iron source and / or a cobalt source, and CTAB in a mixed solvent of methanol and water to obtain a mixed solution. Immerse the above-mentioned sheet-like nickel foam in the mixed solution, then carry out hydrothermal synthesis by a one-pot solvothermal method, and then naturally cool to obtain a multi-metal layered hydroxide catalyst.

[0050] In some alternative embodiments, the size of the nickel foam is preferably 400 mm * 300 mm.

[0051] In some alternative embodiments, the nickel source is a nickel salt; the iron source is an iron salt; the cobalt source is a cobalt salt.

[0052] In some alternative embodiments, the molar ratio of the nickel source to CTAB is preferably 0.9:1.4;

[0053] The total molar ratio of the cobalt source and the iron source to CTAB is 1.2∶1.4.

[0054] In some alternative embodiments, in the mixed solvent, the volume ratio of water to methanol is 6:36; where the water is deionized water.

[0055] In some alternative embodiments, the hydrothermal synthesis process is carried out in a Teflon-lined stainless steel autoclave.

[0056] In some alternative embodiments, the temperature in the hydrothermal synthesis is 180 °C.

[0057] There is an error in this sentence. It should be something like "In some alternative embodiments, the reaction time in the hydrothermal synthesis is 24 h."

[0058] In some alternative embodiments, a method for preparing a nickel foam in-situ grown nickel-iron-cobalt multi-metal layered hydroxide catalyst specifically includes the following steps:

[0059] (1) Prepare mixed solutions with different ratios: Dissolve 0.9 mmol of nickel nitrate (Ni(NO3)2·6H2O), different ratios of iron nitrate (Fe(NO3)3·9H2O) and cobalt nitrate (Co(NO3)2·6H2O) (the total molar amount of iron nitrate and cobalt nitrate is 1.2 mmol), and 1.4 mmol of CTAB in a mixture of 36 mL of methanol and 6 mL of water, and stir at room temperature to form a clear solution;

[0060] (2) Cleaning: Immerse nickel foam (400 mm * 300 mm) in concentrated HCl solution (37 wt%) and ultrasonicate for 5 minutes to remove the NiO layer on the surface and etch it, then wash with water and methanol for 5 minutes to ensure that the residual HCL on the surface of the nickel foam is cleaned;

[0061] (3) Vertically immerse the cleaned nickel foam into the solution, transfer the nickel foam and the solution to a 50 mL Teflon-lined stainless steel autoclave, and in-situ grow at 180 °C in an oven for 24 h. After natural cooling to room temperature, a thin brown film is formed on the nickel foam as the material to be tested.

[0062] The present invention in-situ grows a multi-metal layered hydroxide catalytic material on nickel foam, and utilizes its unique layered structure and multi-metal synergistic effect to significantly improve the CO2 desorption rate. The specific effects are as follows:

[0063] ① Multi-metal synergistic effect: The layered LDH formed by two or more (especially three metals) of nickel, iron, and cobalt has both acid sites (hydroxyl groups provide H + ) and Lewis acid sites (metal cations), greatly improving the acid proton supply ability and accelerating the rate-limiting step (MEAH + deprotonation) in the MEA regeneration process;

[0064] ② Efficient preparation process: The present invention directly in-situ grows a catalyst on a nickel foam substrate by a one-pot solvothermal method, simplifies the synthesis process, and enhances the material stability and active site density;

[0065] ③ Performance optimization: The catalytic material with a FeCo(1 / 5) ratio increases the CO2 desorption rate to 7.68 mmol / min (60.7% higher than the blank) at 120 °C (oil bath temperature), and also has high temperature resistance (reaction condition of 180 °C), suitable for industrial continuous circulation scenarios.

[0066] The present invention discloses a multi-metal layered hydroxide catalyst with a three-dimensional porous structure prepared by the above preparation method.

[0067] The present invention also discloses the application of the above multi-metal layered hydroxide catalyst in the catalytic desorption of CO2; the desorption temperature (oil bath temperature) is 120 °C.

[0068] In the present invention, "room temperature" refers to 20 - 30 °C unless otherwise specified.

[0069] All raw materials used in the present invention are obtained by purchasing in the market. The size of the nickel foam used in the following examples is nickel foam 400 mm * 300 mm.

[0070] The technical solutions of the present invention are further described below through examples.

[0071] Example 1 (FeCo-Ni(1 / 1))

[0072] Soak the nickel foam (400 mm * 300 mm) in a concentrated HCl solution (37 wt%) and ultrasonicate for 5 minutes to remove the NiO layer on the surface, then wash with water and methanol for 5 minutes to ensure the surface of the nickel foam is clean;

[0073] Dissolve 0.9 mmol Ni(NO3)2·6H2O, 0.6 mmol Fe(NO3)3·9H2O, 0.6 mmol Co(NO3)2·6H2O and 1.4 mmol CTAB in a mixture of 36 mL methanol and 6 mL water, stir to form a clear solution; completely immerse the washed nickel foam into the above solution, then transfer it to a 50 mL Teflon-lined stainless steel autoclave, and grow in situ at 180 °C in an oven for 24 h. After the synthesis, cool it naturally to room temperature, and a thin brown film is formed on the nickel foam, named FeCo-Ni(1 / 1).

[0074] Example 2 (FeCo-Ni(5 / ))

[0075] The difference from Example 1 is that on the premise that the total molar amount of iron nitrate and cobalt nitrate is 1.2 mmol, the molar ratio of Fe(NO3)2·6H2O and Co(NO3)2·6H2O is adjusted to 5:1. Other preparation conditions are the same as those in Example 1.

[0076] Example 3 (FeCo-Ni(1 / 5))

[0077] The difference from Example 1 is that on the premise that the total molar amount of iron nitrate and cobalt nitrate is 1.2 mmol, the molar ratio of Fe(NO3)2·6H2O to Co(NO3)2·6H2O is adjusted to 1:5. Other preparation conditions are the same as those in Example 1.

[0078] Example 4 (FeCo-Ni(2 / 1))

[0079] The difference from Example 1 is that on the premise that the total molar amount of iron nitrate and cobalt nitrate is 1.2 mmol, the molar ratio of Fe(NO3)2·6H2O to Co(NO3)2·6H2O is adjusted to 2:1. Other preparation conditions are the same as those in Example 1.

[0080] Example 5 (FeCo-Ni(1 / 2))

[0081] The difference from Example 1 is that on the premise that the total molar amount of iron nitrate and cobalt nitrate is 1.2 mmol, the molar ratio of Fe(NO3)2·6H2O to Co(NO3)2·6H2O is adjusted to 1:2. Other preparation conditions are the same as those in Example 1.

[0082] Example 6 (without adding cobalt source, Fe-Ni)

[0083] The difference from Example 1 is that Co(NO3)2·6H2O is not added, and the usage amounts of the remaining raw materials and the preparation method are the same as those in Example 1. The synthesized material is named Fe-Ni.

[0084] Example 7 (Fe-Ni / Co)

[0085] The difference from Example 6 is that the addition amount of Fe(NO3)3·9H2O is 1.2 mmol, and the usage amounts of other raw materials and the preparation process are the same as those in Example 6. The material is named Fe-Ni / Co.

[0086] Example 8 (without adding iron source, Co-Ni)

[0087] The difference from Example 1 is that Fe(NO3)3·9H2O is not added, and the usage amounts of the remaining raw materials and the preparation method are the same as those in Example 1. The synthesized material is named Co-Ni.

[0088] Example 9 (Co-Ni / Fe)

[0089] The difference from Example 8 is that the addition amount of Co(NO3)2·6H2O is 1.2 mmol, and the usage amounts of other raw materials and the preparation process are the same as those in Example 8. The material is named Co-Ni / Fe.

[0090] Example 10 (FeCo / Ni)

[0091] It is different from Example 1 in that Ni(NO3)2·6H2O is not added, and the amounts of other raw materials used and the preparation process are the same as those in Example 1.

[0092] That is, the molar amounts of the three raw materials (nickel source, iron source, and cobalt source) in the preparation process in Examples 1 - 10 are shown in Table 1 as follows:

[0093] Table 1

[0094]

[0095] Effect verification

[0096] The experimental device used in the present invention includes two parts: an absorption device and a desorption performance test device. The absorption device consists of a CO2 gas cylinder, a gas flowmeter, and a normal-temperature magnetic stirrer, and is used to prepare a rich MEA solution to prepare for the subsequent catalytic desorption experiment. The steps of the absorption experiment are as follows: First, prepare 300 mL of 30 wt% MEA solution, place it on the magnetic stirrer and add a rotor to stir, set the rotation speed to 200 rpm / min, open the CO2 gas cylinder, and control the flow rate at 400 mL / min to ventilate for two and a half hours to prepare a rich MEA solution saturated in absorption.

[0097] The desorption performance test device consists of a magnetic stirrer constant-temperature oil bath, a condenser, a silica drying tube, an online CO2 gas flowmeter, and a desktop computer, and is used to monitor the CO2 desorption rate and cumulative flow released by heating the MEA solution at a certain temperature, so as to test the catalytic desorption performance of the catalyst (where the pH of the desorption environment is about 12).

[0098] The steps of the desorption performance experiment are as follows: Set the temperature of the oil bath to 120 °C and the rotation speed to 200 rpm / min; take 300 mL of the rich MEA solution saturated in absorption and place it in a 500 mL round-bottom flask and add a rotor. After the temperature of the oil bath is stable, put the round-bottom flask containing the rich MEA solution into the oil bath as a set of blank experiments, or as a desorption performance test experiment after adding the catalyst. Connect the round-bottom flask to the condenser and turn on the cooling water; the CO2 gas desorbed from the rich MEA passes through the condenser and enters the silica drying tube to absorb the moisture carried by the gas; the dried CO2 gas enters the CO2 flowmeter to monitor the instantaneous flow rate of CO2; set to record a number every 1 s on the computer, and automatically record the instantaneous flow rate of CO2 through an excel table; draw the change curves of the CO2 desorption amount and desorption rate with time through Origin software.

[0099] The CO2 desorption amount and desorption rate can be calculated by the following formulas:

[0100]

[0101] In the formula: n CO2 (t) —— The instantaneous flow rate of CO2 at the outlet of the flowmeter, mmol;

[0102] M —— The molar volume of the gas at room temperature, taking 22.4 L / mol;

[0103] V CO2 —— The instantaneous flow rate of CO2 monitored by the flowmeter, mL / min

[0104] t —— The reaction time, min;

[0105] Q CO2 —— The desorption rate of CO2, mmol / min.

[0106] Result analysis

[0107] Effect Example 1: First, do a set of blank experiments, and then add catalysts in turn to do desorption performance experiments. Cut one-fourth of the three sheet materials of FeCo-Ni(1 / 1), Fe-Ni, and Co-Ni with a size of 400mm * 300mm, and test the desorption performance of the three catalysts. The CO2 desorption rate curve is as Figure 1 shown in (a). Without adding a catalyst, the highest CO2 desorption rate is 3.89 mmol / min; the corresponding highest desorption rates of the three catalysts of FeCo-Ni(1 / 1), Fe-Ni, and Co-Ni are 5.51, 4.74, and 4.12 mmol / min respectively, and the results are as Figure 1 shown in (b). Therefore, the FeCo-Ni(1 / 1) material has the best catalytic desorption performance. Compared with the blank, the highest CO2 desorption rates of the three catalysts of FeCo-Ni(1 / 1), Fe-Ni, and Co-Ni are increased by 41.6%, 21.9%, and 5.9% respectively. Therefore, the catalytic performance of the FeCo-Ni(1 / 1) material is better than the other two materials, which is due to the doping of three metals, iron, cobalt, and nickel, which increases the active sites on the surface of the catalyst and significantly improves the activity of the catalyst by providing more acidic protons.

[0108] Effect Example 2: According to the previous experiment, weigh the same mass of the three materials of FeCo-Ni(1 / 1), Fe-Ni, and Co-Ni and the nickel foam without doping metal hydroxide for comparison with the blank. 0.18 g of each of the four materials is taken for desorption performance testing, and the results are as Figure 2As shown in (a). The maximum CO2 desorption rate under blank conditions is 4.78 mmol / min, while the maximum CO2 desorption rates after adding 0.18 g of FeCo-Ni(1 / 1), Fe-Ni, Co-Ni, and only nickel foam materials are 5.87, 5.19, 5.65, and 5.16 mmol / min, respectively. The results are as shown in Figure 2 As shown in (b). The FeCo-Ni(1 / 1) material still has the highest CO2 desorption rate, which is 22.8% higher than that of the blank, indicating that the FeCo-Ni(1 / 1) material has the best catalytic performance. The highest CO2 desorption rate of the nickel foam material without doping metal hydroxide is only 7.9% higher than that of the blank, and the Fe-Ni and Co-Ni materials are increased by 8.6% and 18.2% respectively. It further shows that in-situ growth of multi-metal layered hydroxides on the surface of nickel foam can provide more active sites and improve the catalytic activity, and the catalytic performance of the iron, cobalt, and nickel multi-metal layered hydroxide materials is better than that of the two bimetallic hydroxide materials.

[0109] Effect Example 3: Analyze the influence of the doping ratio on the catalytic performance by changing the dosage of iron and cobalt. A total of 1.2 mmol of iron and cobalt bimetals were used, and the ratios of iron and cobalt were set to 5:1, 1:5, 2:1, 1:2, and 1:1 to synthesize five groups of materials. 0.18 g of each group was weighed to test the influence of the multi-metal doping ratio on the desorption rate. The CO2 desorption rate diagram and the maximum desorption rate are respectively as shown in Figure 3 As shown. From the test results, it can be seen that when the ratio of iron and cobalt is 1:5, the maximum desorption rate is 7.68 mmol / min, and the maximum CO2 desorption rate is 60.7% higher than that of the blank, indicating that the FeCo-Ni(1 / 5) material has the best catalytic effect. When the ratio of iron and cobalt is 2:1, the maximum CO2 desorption rate of the FeCo(2 / 1) material is 7.55 mmol / min, which is 57.9% higher than that of the blank. According to Figure 3 As shown in (b), the catalytic effects of the five groups of materials from strong to weak are roughly in the order of: FeCo-Ni(1 / 5), FeCo-Ni(2 / 1), FeCo-Ni(1 / 2), FeCo-Ni(1 / 1), FeCo-Ni(5 / 1).

[0110] Effect Example 4: Next, compare the FeCo-Ni(1 / 1) material with the FeCo / Ni material with the same iron and cobalt doping ratio but without nickel source, two bimetallic nickel-cobalt hydroxide materials with different doping amounts, and two bimetallic nickel-iron hydroxide materials with different doping amounts. Weigh 0.18 g of the six materials for catalytic desorption experiments. The test results are as shown in Figure 4As shown. The results show that the highest CO2 desorption rate of the FeCo-Ni(1 / 1) material is increased by approximately 19.6% compared to FeCo / Ni, indicating that the catalytic performance of FeCo-Ni(1 / 1) is far superior to that of FeCo / Ni. It can be speculated that the nickel-iron-cobalt layered double hydroxide material with Ni(NO3)2·6H2O has more active sites than the iron-cobalt layered double hydroxide material without Ni(NO3)2·6H2O, providing more acidic protons, which plays a crucial role in improving the catalytic desorption performance; by comparing the two bimetallic nickel-cobalt and nickel-iron hydroxide materials with different doping amounts, it can be seen that the maximum CO2 desorption rates of Co-Ni / Fe and Fe-Ni / Co are both greater than those of Co-Ni and Fe-Ni. The maximum CO2 desorption rate of Co-Ni / Fe is increased by 33.3% compared to Co-Ni, while Fe-Ni / Co is increased by 33.1% compared to Fe-Ni. This indicates that the catalytic desorption performance of Co-Ni / Fe and Fe-Ni / Co is superior to that of Co-Ni and Fe-Ni. It can be speculated that for bimetallic hydroxide materials, a higher metal doping amount can increase the number of active sites, thereby improving the catalytic performance.

[0111] Effect Example 5: Select the FeCo-Ni(1 / 5) material with the best catalytic effect, with a catalyst dosage of 0.18 g, and test the influence of the increase in the CO2 desorption rate with the increase in temperature, as Figure 5 shown. Four temperatures of 100°C, 110°C, 120°C, and 130°C were selected as the oil bath temperatures, and the measured desorption temperatures were 89°C, 95°C, 98°C, and 101°C respectively. From the test results, it can be seen that when the temperature rises from 89°C to 98°C, the CO2 desorption rate gradually increases with the increase in temperature, and the CO2 desorption amount also gradually increases. It is also observed that when the actual desorption temperature rises from 89°C to 95°C and from 95°C to 98°C, the maximum CO2 desorption rates increase by 73.9% and 45.7% respectively, indicating that the CO2 desorption rate increases with the increase in temperature. When the temperature rises from 98°C to 101°C, it can be found that the highest CO2 desorption rate remains basically unchanged. It can be concluded that temperature has an important influence on the CO2 desorption rate. Within a certain temperature range, the CO2 desorption rate increases with the increase in temperature. Therefore, in engineering applications, the temperature can be controlled within a certain range, and at this time, increasing the temperature has a more significant effect on improving the CO2 desorption rate and saves operating costs.

[0112] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A preparation method of a multi-metal layered hydroxide catalytic material, characterized in that, It includes the following steps: Adopt a one-pot solvothermal method, soak nickel foam in a mixed solution for hydrothermal synthesis to prepare a multi-metal layered hydroxide catalytic material; Among them, the mixed solution includes a surfactant, a solvent, and at least two of a nickel source, an iron source, and a cobalt source.

2. The preparation method of a multi-metal layered hydroxide catalytic material according to claim 1, characterized in that, The nickel source, iron source, and cobalt source are all soluble metal salts; and / or, The surfactant is cetyltrimethylammonium bromide or octadecyltrimethylammonium chloride.

3. The preparation method of a multi-metal layered hydroxide catalytic material according to claim 1, characterized in that, The molar ratio of the nickel source to the surfactant is 0.9∶1.4; and / or, The total amount of substance of the iron source and the cobalt source to the amount of substance of the surfactant is 1.2∶1.

4.

4. The preparation method of a multi-metal layered hydroxide catalytic material according to claim 3, characterized in that, The molar ratio of the iron source to the cobalt source is (1∶5)-(2∶1).

5. The preparation method of a multi-metal layered hydroxide catalytic material according to claim 4, characterized in that, The molar ratio of the iron source to the cobalt source is 1∶5.

6. The preparation method of a multi-metal layered hydroxide catalytic material according to claim 1, characterized in that, The solvent is a mixed solution of water and methanol.

7. The preparation method of a multi-metal layered hydroxide catalytic material according to claim 1, characterized in that, The conditions in the hydrothermal synthesis process are: Perform hydrothermal synthesis at 180°C for 12-24 h.

8. A multi-metal layered hydroxide catalytic material, characterized in that, Prepared by the preparation method according to any one of claims 1-7.

9. The multi-metal layered hydroxide catalytic material according to claim 8, characterized in that, The composition of the multi-metal layered hydroxide catalytic material is NixFe y Co z -LDH; Among them, x = 0.9, y + z = 1.

2.

10. Use of the multi-metal layered hydroxide catalytic material according to claim 9 in the catalytic desorption of CO2.

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