Preparation method of high-entropy metal oxide for preparing synthesis gas through carbonate pyrolysis carbon dioxide and methane dry reforming

Abstract

The invention discloses a preparation method of a high-entropy metal oxide for preparing synthesis gas by carbonate pyrolysis carbon dioxide and methane dry reforming. The high-entropy composite metal oxide is obtained by nucleation of a mixed salt solution and an alkali source solution in a nucleation reactor, crystallization, washing, drying, grinding and high-temperature roasting. The high-entropy composite metal oxide prepared by the method is used for ultrahigh-temperature coupling reaction for preparing synthesis gas by taking carbonate pyrolysis industrial tail gas CO2 and CH4 as raw materials, the synthesis gas is efficiently prepared, and meanwhile, full utilization of waste heat in the carbonate pyrolysis process and resource conversion of CO2 are realized; the contribution is made for promoting the development of environment-friendly society and circular economy; the high-entropy composite metal oxide catalyst has excellent activity, selectivity and stability.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and in particular relates to a method for preparing a high entropy metal oxide for preparing synthesis gas by pyrolyzing carbon dioxide from carbonate and dry reforming with methane. Background Art

[0002] The metal oxides produced by carbonate pyrolysis are important raw materials in process industries such as steel, cement, and refractory materials. However, the process of carbonate decomposition to produce industrial raw materials will also produce and release a large amount of CO2, causing a serious greenhouse effect. The carbon emissions generated by the related process industries exceed 50% of the total national industrial carbon emissions. Therefore, it is imperative and urgent to utilize the CO2 in the exhaust gas of carbonate pyrolysis industry.

[0003] Methane dry reforming is an effective method to convert two greenhouse gases into synthesis gas (H2 + CO), which is then used in downstream reactions such as Fischer-Tropsch synthesis to produce higher value chemicals. Synthesis gas is not only a basic raw material for the chemical industry, which can be used to produce chemicals such as methanol and synthetic ammonia, but also an important source of clean energy. However, the industrial application of DRM technology is limited by poor catalyst stability, easy carbon deposition and harsh reaction conditions.

[0004] So far, the research on DRM has been very extensive, in which precious metals are used for the reaction. Although the catalytic effect is significant, the high cost limits its large-scale application. In contrast, non-precious metal catalysts, especially nickel-based catalysts, have become a hot topic of research due to their cost advantages and good catalytic performance. In recent years, through the innovation of materials science, new nickel-based catalysts with anti-carbon deposition performance have been developed. Among them, the emergence of high-entropy composite metal oxide catalysts not only effectively solves the problem of high-temperature stability of catalysts, but also significantly improves the catalytic efficiency, opening up a new direction for the industrial application of DRM technology.

[0005] Existing high-entropy composite metal oxide catalysts face multiple challenges in the catalytic methane dry reforming process: they are often unstable at high temperatures and are prone to sintering and structural damage, resulting in rapid decay of catalytic activity; at the same time, carbon is easily deposited on the catalyst surface, which not only reduces the catalytic efficiency but also may cause catalyst blockage and failure. In addition, existing catalysts have poor adaptability to reaction conditions and require strict operating conditions to maintain their performance, which increases the complexity and cost of industrial applications. More importantly, many catalysts rely on expensive precious metals, which significantly increases production costs and limits their potential for large-scale applications. Summary of the invention

[0006] The present invention is proposed to overcome the shortcomings of the prior art, and its purpose is to provide a method for preparing high entropy metal oxides for preparing synthesis gas by pyrolysis of carbonate with carbon dioxide and dry reforming of methane.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for preparing a high entropy metal oxide for preparing synthesis gas by pyrolysis of carbonate with carbon dioxide and dry reforming of methane comprises the following steps:

[0009] (I) dissolving a soluble nickel salt, a soluble cobalt salt, a soluble magnesium salt, a soluble iron salt and a soluble aluminum salt in deionized water, and dispersing them by ultrasonication to obtain a mixed salt solution;

[0010] (II) preparing an alkali source solution;

[0011] (III) the mixed salt solution and the alkali source solution are simultaneously and slowly added into a conventional colloid mill, and the colloid mill is stirred at a high speed of 5000 rad / min for 5 minutes to obtain a primary product;

[0012] (IV) placing the initial product into a reaction vessel for crystallization to obtain an intermediate product;

[0013] (V) washing, drying and grinding the intermediate product to obtain a high entropy composite metal oxide catalyst precursor;

[0014] (VI) calcining the high entropy composite metal oxide catalyst precursor at high temperature to obtain a high entropy composite metal oxide catalyst.

[0015] In the above technical scheme, the soluble nickel salt is any one or more of nickel nitrate or nickel chloride; the soluble cobalt salt is any one or more of cobalt nitrate or cobalt chloride; the soluble magnesium salt is any one or more of magnesium nitrate or magnesium chloride; the soluble iron salt is any one or more of iron nitrate or iron chloride; the soluble aluminum salt is any one or more of aluminum nitrate or aluminum chloride.

[0016] In the above technical scheme, the molar ratio of soluble nickel salt, soluble cobalt salt, soluble magnesium salt, soluble iron salt and soluble aluminum salt in step (I) is (0.1-1):(0.1-1):1:1:1; preferably 1:1:1:1:1, 0.5:0.5:1:1:1, 0.25:0.25:1:1:1 or 0.1:0.1:1:1:1.

[0017] In the above technical solution, the ultrasonic dispersion time in step (I) is 5 min to 30 min.

[0018] In the above technical solution, the alkaline source solution is a mixed aqueous solution of sodium hydroxide and sodium carbonate, the molar amount of sodium carbonate is 2 times the total molar amount of trivalent cations in the mixed salt solution; the molar amount of sodium hydroxide is 1.6 times the total molar amount of cations in the mixed salt solution.

[0019] In the above technical solution, the rotation speed of the nucleation stirring in step (III) is 3000 rpm, and the nucleation stirring time is 5 minutes.

[0020] In the above technical solution, the crystallization condition of step (IV) is crystallization at 120° C. for 24 hours.

[0021] In the above technical solution, the drying condition in step (V) is drying at 80° C. for 24 hours.

[0022] In the above technical solution, the high temperature calcination condition of step (VI) is calcination at 900° C. for 4 hours in an air atmosphere.

[0023] A high entropy composite metal oxide prepared by the above method, wherein the high entropy composite metal oxide has the characteristics of multi-component composition and different element ratios, and the chemical formula of the high entropy composite metal oxide is Ni x Co y Mg1Fe1Al1-LDOs, wherein: x = 0.1 to 1; y = 0.1 to 1; the high entropy composite metal oxide catalyst has the characteristics of multi-component composition and different element ratios, and its chemical formula is Ni x Co y Mg1Fe1Al1-LDOs, wherein: x = 0.1 to 1; y = 0.1 to 1; preferably, the chemical formula of the high entropy composite metal oxide catalyst is Ni1Co1Mg1Fe1Al1-LD, Ni 0.5 Co 0.5 Mg1Fe1Al1-LD, Ni 0.25 Co 0.25 Mg1Fe1Al1-LDO or Ni 0.1 Co 0.1 Mg1Fe1Al1-LDO; By providing flexible adjustment space in the content of Ni and Co (x = 0.1 ~ 1; y = 0.1 ~ 1) while maintaining a constant ratio of Mg, Fe, and Al, the catalyst cleverly integrates the core characteristics of high entropy materials. This composition design not only promotes the formation of solid solution structure and enhances the uniformity and stability of the material, but also optimizes the surface properties and active site distribution of the catalyst through complex electronic and geometric effects. In addition, the thermodynamic and kinetic stability brought by the high entropy effect enables the catalyst to remain efficient and stable under harsh reaction conditions.

[0024] A method for preparing synthesis gas by coupling carbonate pyrolysis CO2 and methane dry reforming with a high entropy composite metal oxide, specifically comprising: loading a high entropy composite metal oxide prepared by the method according to any one of claims 1 to 7 in a continuous fixed bed reactor under normal pressure, and then introducing a mixed gas of methane and carbon dioxide in a volume ratio of 1:1 for reaction, the reaction temperature is 500°C to 900°C, and the space velocity is 60000ml·g -1 ·h -1 ~3000000ml·g -1 ·h -1 , producing H2 and CO.

[0025] The beneficial effects of the present invention are:

[0026] The present invention provides a method for preparing a high-entropy metal oxide for ultra-high temperature coupling reaction of carbon dioxide from industrial tail gas from carbonate pyrolysis and dry reforming of methane to produce synthesis gas, thereby achieving efficient preparation of synthesis gas and simultaneously achieving full utilization of waste heat from carbonate pyrolysis and resource conversion of CO2, thus contributing to promoting the development of an environmentally friendly society and a circular economy; the high-entropy composite metal oxide catalyst has excellent activity, selectivity and stability.

[0027] The high-entropy composite metal oxide of the present invention has excellent high-temperature stability, can maintain structural integrity and stable activity under extreme conditions, and effectively inhibits sintering; at the same time, the high-entropy composite metal oxide exhibits excellent resistance to carbon deposition, ensuring long-term stable operation and efficient catalytic conversion. In addition, the high-entropy composite metal oxide of the present invention has a wide range of adaptability to reaction conditions, can work efficiently within a wide range of temperature and space velocity, and simplifies the industrial operation process. By adopting more cost-effective non-precious metal components, the high-entropy composite metal oxide of the present invention greatly reduces production costs, providing strong support for the economic feasibility and environmental sustainability of methane dry reforming technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a scanning electron microscope photograph of the high entropy composite metal oxide prepared in Example 1 of the present invention;

[0029] Figure 2 is a performance diagram of the high entropy composite metal oxide prepared in Example 1 of the present invention at different space velocities;

[0030] Figure 3 is a stability performance diagram of the high entropy composite metal oxide prepared in Example 1 of the present invention;

[0031] Figure 4 It is a performance comparison chart of the high entropy composite metal oxides prepared in Examples 1 to 4 of the present invention.

[0032] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0034] Example 1

[0035] A method for preparing a Ni1Co1Mg1Fe1Al1-LDO catalyst, the specific steps are as follows:

[0036] First, a mixed solution of 0.01 mol / L nickel nitrate, 0.01 mol / L cobalt nitrate, 0.01 mol / L magnesium nitrate, 0.01 mol / L iron nitrate and 0.01 mol / L aluminum nitrate is prepared with deionized water, and a mixed solution of 1.6 times the total molar amount of cations and 2 times the molar amount of trivalent cations is prepared with deionized water; the two mixed solutions are transferred to a nucleation reactor and stirred for 5 minutes; the mixed solution is charged into a reactor and crystallized at 120°C for 24 hours to obtain a Ni1Co1Mg1Fe1Al1-LDH catalyst precursor; the obtained product is washed, dried, and ground, and then heated to 900°C at 5°C / min in a muffle furnace, roasted for 4 hours, and then cooled to room temperature at 10°C / min.

[0037] 0.03 g of the catalyst prepared in this example was weighed and used for coupling carbonate pyrolysis CO2 with methane dry reforming to prepare synthesis gas. Under normal pressure, 0.03 g of the catalyst was loaded into a continuous fixed bed reactor, and then a mixture of methane and carbon dioxide was introduced at a volume ratio of 1:1 to react to generate H2 and CO. The reaction was carried out at 60000 ml·g -1 ·h -1 、120000ml·g -1 ·h -1 and 3000000ml·g -1 ·h -1 The catalytic performance was tested at reaction temperatures of 650°C, 700°C, 750°C, 800°C, 850°C and 900°C. The reaction was carried out for 1 hour at each temperature. The test results are shown in Figure 4 .

[0038] The SEM image of the Ni1Co1Mg1Fe1Al1-LDO catalyst prepared in this example is as follows: Figure 1 As shown, from Figure 1 It can be seen that the hydrotalcite nanosheets have a stable morphology.

[0039] from Figure 2 and Figure 3 It can be seen that the Ni1Co1Mg1Fe1Al1-LDO catalyst prepared in this example has good catalytic activity and stability.

[0040] Example 2

[0041] A Ni 0.5 Co 0.5 The preparation method of Mg1Fe1Al1-LDO catalyst comprises the following specific steps:

[0042] First, a mixed solution of 0.01 mol / L nickel nitrate, 0.01 mol / L cobalt nitrate, 0.01 mol / L magnesium nitrate, 0.01 mol / L iron nitrate and 0.01 mol / L aluminum nitrate was prepared with deionized water, and a mixed solution of 1.6 times the total molar amount of cations in sodium hydroxide and 2 times the molar amount of trivalent cations in sodium carbonate was prepared with deionized water; the two mixed solutions were transferred to a nucleation reactor and stirred for 5 min; the mixed solution was charged into a reactor and crystallized at 120 ° C for 24 h to obtain Ni 0.5 Co 0.5 Mg1Fe1Al1-LDH catalyst precursor; the obtained product was washed, dried, ground, heated to 900°C at 5°C / min in a muffle furnace, calcined for 4 hours, and then cooled to room temperature at 10°C / min.

[0043] 0.03 g of the catalyst prepared in this example was weighed and used for coupling carbonate pyrolysis CO2 with methane dry reforming to prepare synthesis gas. Under normal pressure, 0.03 g of the catalyst was loaded into a continuous fixed bed reactor, and then a mixture of methane and carbon dioxide was introduced at a volume ratio of 1:1 to react to generate H2 and CO. The reaction was carried out at 60000 ml·g -1 ·h -1 、120000ml·g -1 ·h -1 and 3000000ml·g -1 ·h -1 The catalytic performance was tested at reaction temperatures of 650°C, 700°C, 750°C, 800°C, 850°C and 900°C. The reaction was carried out for 1 hour at each temperature. The test results are shown in Figure 4 .

[0044] Example 3

[0045] A Ni 0.25 Co 0.25 The preparation method of Mg1Fe1Al1-LDO catalyst comprises the following specific steps:

[0046] First, a mixed solution of 0.01 mol / L nickel nitrate, 0.01 mol / L cobalt nitrate, 0.01 mol / L magnesium nitrate, 0.01 mol / L iron nitrate and 0.01 mol / L aluminum nitrate was prepared with deionized water, and a mixed solution of 1.6 times the total molar amount of cations in sodium hydroxide and 2 times the molar amount of trivalent cations in sodium carbonate was prepared with deionized water; the two mixed solutions were transferred to a nucleation reactor and stirred for 5 min; the mixed solution was charged into a reactor and crystallized at 120 ° C for 24 h to obtain Ni 0.25 Co 0.25 Mg1Fe1Al1-LDH catalyst precursor; the obtained product was washed, dried, ground, heated to 900°C at 5°C / min in a muffle furnace, calcined for 4 hours, and then cooled to room temperature at 10°C / min.

[0047] 0.03 g of the catalyst prepared in this example was weighed and used for coupling carbonate pyrolysis CO2 with methane dry reforming to prepare synthesis gas. Under normal pressure, 0.03 g of the catalyst was loaded into a continuous fixed bed reactor, and then a mixture of methane and carbon dioxide was introduced at a volume ratio of 1:1 to react to generate H2 and CO. The reaction was carried out at 60000 ml·g -1 ·h -1 、120000ml·g -1 ·h -1 and 3000000ml·g -1 ·h -1 The catalytic performance was tested at reaction temperatures of 650°C, 700°C, 750°C, 800°C, 850°C and 900°C. The reaction was carried out for 1 hour at each temperature. The test results are shown in Figure 4 .

[0048] Example 4

[0049] A Ni 0.1 Co 0.1 The preparation method of Mg1Fe1Al1-LDO catalyst comprises the following specific steps:

[0050] First, a mixed solution of 0.01 mol / L nickel nitrate, 0.01 mol / L cobalt nitrate, 0.01 mol / L magnesium nitrate, 0.01 mol / L iron nitrate and 0.01 mol / L aluminum nitrate was prepared with deionized water, and a mixed solution of 1.6 times the total molar amount of cations in sodium hydroxide and 2 times the molar amount of trivalent cations in sodium carbonate was prepared with deionized water; the two mixed solutions were transferred to a nucleation reactor and stirred for 5 min; the mixed solution was charged into a reactor and crystallized at 120 ° C for 24 h to obtain Ni 0.1 Co 0.1Mg1Fe1Al1-LDH catalyst precursor; the obtained product was washed, dried, ground, heated to 900°C at 5°C / min in a muffle furnace, calcined for 4 hours, and then cooled to room temperature at 10°C / min.

[0051] 0.03 g of the catalyst prepared in this example was weighed and used for coupling carbonate pyrolysis CO2 with methane dry reforming to prepare synthesis gas. Under normal pressure, 0.03 g of the catalyst was loaded into a continuous fixed bed reactor, and then a mixture of methane and carbon dioxide was introduced at a volume ratio of 1:1 to react to generate H2 and CO. The reaction was carried out at 60000 ml·g -1 ·h -1 、120000ml·g -1 ·h -1 and 3000000ml·g -1 ·h -1 The catalytic performance was tested at reaction temperatures of 650°C, 700°C, 750°C, 800°C, 850°C and 900°C. The reaction was carried out for 1 hour at each temperature. The test results are shown in Figure 4 .

[0052] Figure 4 The performance comparison diagram of the catalysts prepared in Examples 1 to 4 of the present invention in the preparation of synthesis gas by coupling carbonate pyrolysis CO2 and methane dry reforming is shown in the figure. As can be seen from the figure, Ni1Co1Mg1Fe1Al1-LDO, Ni 0.5 Co 0.5 Mg1Fe1Al1-LDO,Ni 0.25 Co 0.25 Mg1Fe1Al1-LDO,Ni 0.1 Co 0.1 The Mg1Fe1Al1-LDO catalyst has good catalytic performance, and the Ni1Co1Mg1Fe1Al1-LDO catalyst has the best catalytic activity.

[0053] The high entropy composite metal oxide prepared by the present invention has a synergistic catalytic effect with MgFeAlO4 by regulating a relatively low NiCo content. The NiCo dispersion is high, which is beneficial to suppressing defect sites on NiCo particles. MgFeAlO4 promotes the adsorption of carbon dioxide, improves the conversion rate of carbon dioxide, and realizes the mixed and efficient utilization of multiple metal elements.

[0054] The high entropy composite metal oxide prepared by the present invention is applied in the dry reforming reaction to show good catalytic performance. At 900°C, the conversion rate of CO2 can reach 98.6%, and the high entropy composite metal oxide has good stability in the reaction. Compared with the catalyst of the prior art, the high entropy composite metal oxide provided by the present invention has strong high temperature anti-sintering performance, simple preparation method and low production cost; at the same time, in the application of the high entropy composite metal oxide of the present invention, the carbonate pyrolysis CO2 and the methane dry reforming reaction process are co-thermally coupled, making full use of the high calorific value CO2 contained in the carbonate pyrolysis industrial tail gas, and utilizing the excellent catalytic performance of the high entropy composite metal oxide, not only can the high temperature waste heat generated by the carbonate pyrolysis process be efficiently converted into chemical reaction energy, but also the carbon source in the carbonate can be converted into a reaction raw material, replacing part of the CO2 gas, and reacting with methane to generate high-value products such as H2 and CO, so as to achieve the same catalytic system, further simplify the production steps, and reduce energy consumption and production costs.

[0055] The present invention realizes the full utilization of high-temperature waste heat generated by carbonate pyrolysis, and at the same time promotes the secondary utilization of carbon sources in carbonates, effectively reduces CO2 emissions, promotes the efficient production of synthesis gas, opens up a new way for carbon cycle and sustainable utilization of resources, and has significant environmental and economic benefits.

[0056] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0057] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high entropy metal oxide for preparing synthesis gas by pyrolysis of carbonate with carbon dioxide and dry reforming of methane, characterized in that: The following steps are involved: (I) dissolving a soluble nickel salt, a soluble cobalt salt, a soluble magnesium salt, a soluble iron salt and a soluble aluminum salt in deionized water, and dispersing them by ultrasonication to obtain a mixed salt solution; (II) preparing an alkali source solution; (III) adding the mixed salt solution and the alkali source solution to the colloid mill simultaneously and slowly, stirring at high speed, to obtain the initial product; (IV) placing the initial product into a reaction vessel for crystallization to obtain an intermediate product; (V) washing, drying and grinding the intermediate product to obtain a high entropy composite metal oxide catalyst precursor; (VI) calcining the high entropy composite metal oxide catalyst precursor at high temperature to obtain a high entropy composite metal oxide catalyst.

2. The method for preparing a high entropy metal oxide for preparing synthesis gas by dry reforming of carbon dioxide from carbonate pyrolysis and methane according to claim 1, characterized in that: The soluble nickel salt is any one or more of nickel nitrate or nickel chloride; the soluble cobalt salt is any one or more of cobalt nitrate or cobalt chloride; the soluble magnesium salt is any one or more of magnesium nitrate or magnesium chloride; the soluble iron salt is any one or more of iron nitrate or iron chloride; the soluble aluminum salt is any one or more of aluminum nitrate or aluminum chloride.

3. The method for preparing a high entropy metal oxide for preparing synthesis gas by dry reforming of carbon dioxide from carbonate pyrolysis and methane according to claim 1, characterized in that: In the step (I), the molar ratio of the soluble nickel salt, the soluble cobalt salt, the soluble magnesium salt, the soluble iron salt and the soluble aluminum salt is (0.1-1):(0.1-1):1:1:

1.

4. The method for preparing a high entropy metal oxide for preparing synthesis gas by dry reforming of carbon dioxide from carbonate pyrolysis and methane according to claim 1, characterized in that: The ultrasonic dispersion time in step (I) is 5 min to 30 min.

5. The method for preparing a high entropy metal oxide for preparing synthesis gas by dry reforming of carbon dioxide with methane by pyrolysis of carbonate according to claim 1, characterized in that: The alkaline source solution is a mixed aqueous solution of sodium hydroxide and sodium carbonate, the molar amount of sodium carbonate is 2 times the total molar amount of trivalent cations in the mixed salt solution; the molar amount of sodium hydroxide is 1.6 times the total molar amount of cations in the mixed salt solution.

6. The method for preparing a high entropy metal oxide for preparing synthesis gas by dry reforming of carbon dioxide from carbonate pyrolysis and methane according to claim 1, characterized in that: In the step (III), the rotation speed of the colloid mill is 5000 rad / min, and the stirring time of the colloid mill is 5 minutes; and the crystallization condition in the step (IV) is crystallization at 120° C. for 24 hours.

7. The method for preparing a high entropy metal oxide for preparing synthesis gas by dry reforming of carbon dioxide with methane by pyrolysis of carbonate according to claim 1, characterized in that: The drying condition of step (V) is drying at 80° C. for 24 hours; the high temperature calcination condition of step (VI) is calcining at 900° C. for 4 hours in an air atmosphere.

8. A high entropy composite metal oxide prepared by the method according to any one of claims 1 to 7, characterized in that: The chemical formula of the high entropy composite metal oxide is Ni x Co y Mg1Fe1Al1-LDOs, wherein: x=0.1~1; y=0.1~1.

9. Use of a high entropy composite metal oxide prepared by the method according to any one of claims 1 to 7 in the preparation of synthesis gas by coupling carbonate pyrolysis CO2 with methane dry reforming.

10. A method for preparing synthesis gas by coupling carbonate pyrolysis CO2 with methane dry reforming, characterized in that: Specifically, under normal pressure, a high entropy composite metal oxide prepared by the method according to any one of claims 1 to 7 is loaded into a continuous fixed bed reactor, and then a mixed gas of methane and carbon dioxide is introduced in a volume ratio of 1:1 for reaction, the reaction temperature is 500°C to 900°C, the space velocity is 60000ml·g -1 ·h -1 ~3000000ml·g -1 ·h -1 , producing H2 and CO.

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