A Ni-Cu-based coal catalytic gasification catalyst, its preparation method and application

Abstract

A Ni-Cu-based coal catalytic gasification catalyst, its preparation method, and its application are disclosed. The catalyst comprises metallic nickel and metallic copper. A modified co-precipitation method is used to thoroughly mix metallic nickel and metallic copper in a 1:1 molar ratio, followed by calcination to obtain NiCuO2 crystals with a high specific surface area. Due to its layered structure and high specific surface area, the catalyst can fully contact coal molecules, thereby improving the carbon conversion rate of the gasification reaction. Simultaneously, the uniform mixing of metallic nickel and metallic copper at the microscopic level results in better dispersion, significantly improving the catalytic performance and enhancing the oxygen transfer process during coal catalytic gasification. This Ni-Cu-based catalyst preparation method is simple and offers several advantages over existing coal catalytic gasification catalysts, including high activity, sulfur resistance, and economic efficiency.

Description

Technical Field

[0001] This invention relates to a multi-metal catalyst for coal catalytic gasification, its preparation method and application, specifically to a Ni-Cu-based coal catalytic gasification catalyst, its preparation method and application. Background Technology

[0002] Coal is an important fossil fuel, but traditional utilization methods cause environmental problems, greenhouse gas emissions, and resource waste, necessitating more efficient and environmentally friendly coal gasification technologies. As a core technology for the clean and efficient utilization of coal, gasification technology is not only significant for energy production but also widely used in chemical, petrochemical, and other industrial applications.

[0003] Currently, metal catalysts are added during coal gasification to improve the reaction rate and product quality. For the gasification of oxygen-containing gases, the entire gasification reaction can be described as an oxygen transfer process with metal oxides as the catalytic active centers. Essentially, the metal abstracts oxygen from the gas to form metal oxides, which then transfer oxygen to the active carbon sites, where it combines with the carbon to form CO and new active sites. To enhance this oxygen transfer process, the designed metal catalyst must possess excellent catalytic activity, enabling it to rapidly transfer large amounts of oxygen to the active carbon sites; and excellent dispersibility, allowing for sufficient contact with carbon atoms to form more catalytic active centers.

[0004] Ni-based catalysts (NiO) exhibit excellent catalytic performance due to their p-type semiconductor properties. After capturing oxygen from the gas, their crystal lattice holds excess oxygen, creating cation vacancies that rapidly transfer oxygen to the active carbon sites. Furthermore, due to their high reaction rate, good stability, and low cost, 98% of the Ni can be recovered via ammonia leaching after the reaction, making them a promising coal catalytic gasification catalyst worthy of further research. However, Ni-based catalysts are susceptible to sulfur poisoning and deactivation at high temperatures, and their poor dispersibility leads to agglomeration, significantly reducing their activity and hindering their industrial application. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of easy agglomeration and low catalytic activity of existing Ni-based catalysts, and to provide a Ni-Cu-based coal catalytic gasification catalyst, its preparation method and application. This catalyst is synthesized by introducing Cu element into Ni-based catalysts to synthesize NiCuO2 crystals, which uniformly mix metallic nickel and metallic copper at the microscopic level, resulting in better dispersion and significantly improving the catalytic performance of the catalyst.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A Ni-Cu-based coal catalytic gasification catalyst, wherein the catalyst comprises metallic nickel and metallic copper, and its main component is NiCuO2 crystals. Figure 2 As shown, in the NiCuO2 crystal, copper and nickel ions are located in a single plane, with each copper ion covalently bonded to surrounding oxygen ions, forming a Cu-O layer. These Cu-O layers are connected by nickel ions (Ni), forming a two-dimensional layered structure with a high specific surface area, providing more catalytic active sites and enabling the catalyst to fully contact coal molecules, thereby accelerating the carbon conversion rate of the gasification reaction. Simultaneously, the movement of sulfur (S) between the Cu-O layers is restricted, significantly enhancing the sulfur resistance of Ni. Furthermore, the uniform mixing of metallic nickel and metallic copper at the microscopic level results in better dispersion and significantly improves the catalytic performance. The finished catalyst has a particle size of less than 120 mesh (<125 μm).

[0008] A method for preparing the above-mentioned Ni-Cu-based coal catalytic gasification catalyst, wherein the method comprises:

[0009] Step 1: Mix the soluble nickel salt and the soluble copper salt, and dissolve them completely in deionized water to obtain a coprecipitation precursor mixed solution;

[0010] Step 2: Under stirring, the precursor mixture obtained in Step 1 and sodium hydroxide solution are slowly added dropwise to sodium carbonate solution to form a coprecipitate of Ni and Cu hydroxides. After filtration, washing, dehydration and drying, the coprecipitate precursor powder is obtained.

[0011] Step 3: The coprecipitated precursor powder obtained in Step 2 is calcined to obtain NiCuO2 crystals, which are then ground and sieved to finally obtain Ni-Cu-based coal catalytic gasification catalyst with a particle size of less than 120 mesh (<125μm).

[0012] Further, in step one, the soluble nickel salt is one of Ni(NO3)2, NiSO4, or NiCl2; the soluble copper salt is one of Cu(NO3)2, CuSO4, or CuCl2.

[0013] Furthermore, in step two, the molar ratio of Ni, Cu, and sodium carbonate is controlled to be 10:10:1-2.

[0014] Further, in step one, the soluble nickel salt and the soluble copper salt are mixed in the same molar amount, and the concentrations of Ni and Cu in the resulting mixed solution are both 0.5 mol / L; in step two, the concentration of the sodium carbonate solution is 0.1 mol / L.

[0015] Furthermore, in step two, the volume ratio of the precursor mixture solution to the sodium carbonate solution is 2:1, and sodium hydroxide is added in real time to control the pH of the entire solution to be maintained between 9 and 10. The concentration of the sodium hydroxide solution is 1.5 mol / L.

[0016] Furthermore, in step two, the temperature is maintained at 80℃ during the precipitation process, the precipitation time is 20-24h, and the pH is maintained between 9 and 10 during the precipitation process.

[0017] Furthermore, in step two, after filtration, the product is washed 6 times with deionized water, dehydrated 3 times with anhydrous ethanol, and dried at 80°C for 10-12 hours.

[0018] Furthermore, in step three, the calcination temperature is 400-500℃ and the time is 4-5 hours.

[0019] Application of a Ni-Cu-based coal catalytic gasification catalyst prepared by the above method in coal catalytic gasification.

[0020] The advantages of this invention over the prior art are as follows:

[0021] (1) The catalyst of the present invention is coupled with Ni and Cu, which have high catalytic activity. The preparation method is simple and has many advantages such as high activity, sulfur resistance and economy compared with existing coal catalytic gasification catalysts.

[0022] (2) The present invention prepared NiCuO2 crystals with a high specific surface area by a modified co-precipitation method. Due to its layered structure, the catalyst can fully contact the coal molecules, thereby improving the carbon conversion rate of the gasification reaction.

[0023] (3) The present invention uniformly mixes metallic nickel and metallic copper at the micro level, resulting in better dispersion and significantly improving the catalytic performance of the catalyst. Attached Figure Description

[0024] Figure 1 This is a comparison chart of carbon conversion rates in coal gasification using Ni-Cu-based coal catalytic gasification catalysts with different addition amounts and single-metal catalysts.

[0025] Figure 2 This is a crystal structure diagram. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0027] The catalyst of this invention comprises metallic nickel and metallic copper. A modified co-precipitation method is used to thoroughly mix metallic nickel and metallic copper in a 1:1 molar ratio, followed by calcination to prepare NiCuO2 crystals with a high specific surface area. Due to its layered structure and high specific surface area, the catalyst can fully contact coal molecules, thereby improving the carbon conversion rate of the gasification reaction. Simultaneously, the uniform mixing of metallic nickel and metallic copper at the microscopic level results in better dispersion, significantly improving the catalytic performance and enhancing the oxygen transfer process during coal catalytic gasification. This Ni-Cu-based catalyst preparation method is simple and offers several advantages over existing coal catalytic gasification catalysts, including high activity, sulfur resistance, and cost-effectiveness.

[0028] Example 1:

[0029] A method for preparing a Ni-Cu-based coal catalytic gasification catalyst, the specific steps of which are as follows:

[0030] (1) Weigh 4.64 g (0.03 mol) NiSO4 and 4.79 g (0.03 mol) CuSO4 and dissolve them completely in 60 mL of deionized water. While stirring, slowly add the precursor mixture and a 1.5 mol / L sodium hydroxide solution dropwise to 30 mL of a 0.1 mol / L sodium carbonate solution. Precipitate at 80 °C for 20 h, maintaining the pH between 9 and 10 during the precipitation process to form a co-precipitate of Ni and Cu hydroxides.

[0031] (2) After precipitation, the precipitate was filtered out, washed 6 times with deionized water, and then dehydrated 3 times with anhydrous ethanol. The precipitate was dried at 80℃ for 12 h to obtain Ni-Cu co-precipitated precursor powder. NiCuO2 crystals were prepared by calcination at 450℃ for 4 h. After grinding and sieving, Ni-Cu-based coal catalytic gasification catalyst with a particle size less than 120 mesh (<125 μm) was obtained. The specific surface area of ​​this catalyst was measured to be 73.7 m². 2 / g, density is 6.51g / cm³ 3 The yield was 86%.

[0032] Example 2:

[0033] A method for preparing a Ni-Cu-based coal catalytic gasification catalyst, the specific steps of which are as follows:

[0034] (1) Weigh 7.13 g (0.03 mol) NiCl2·6H2O and 5.11 g (0.03 mol) CuCl2·2H2O and dissolve them completely in 60 mL of deionized water. While stirring, slowly add the precursor mixture and a 1.5 mol / L sodium hydroxide solution dropwise to 30 mL of a 0.1 mol / L sodium carbonate solution. Precipitate at 80 °C for 20 h, maintaining the pH between 9 and 10 during the precipitation process to form a co-precipitate of Ni and Cu hydroxides.

[0035] (2) After precipitation, the precipitate was filtered out, washed 6 times with deionized water, and then dehydrated 3 times with anhydrous ethanol. The precipitate was dried at 80℃ for 12 h to obtain Ni-Cu co-precipitated precursor powder. NiCuO2 crystals were prepared by calcination at 450℃ for 4 h. After grinding and sieving, Ni-Cu-based coal catalytic gasification catalyst with a particle size less than 120 mesh (<125 μm) was obtained. The specific surface area of ​​this catalyst was measured to be 73.7 m². 2 / g, density is 6.50g / cm³ 3 The yield was 85%.

[0036] Comparative Example 1:

[0037] A laboratory preparation method for a Ni-Cu-based coal catalytic gasification catalyst, the specific steps of which are as follows:

[0038] (1) Weigh 4.64 g (0.03 mol) NiSO4 and 4.79 g (0.03 mol) CuSO4 and dissolve them completely in 60 mL of deionized water. While stirring, slowly add the precursor mixture solution dropwise to 100 mL of 1.5 mol / L ammonia solution. Precipitate at 80 °C for 20 h, and maintain the pH between 9 and 10 during the precipitation process to form a co-precipitate of Ni and Cu hydroxides.

[0039] (2) After precipitation, the precipitate was filtered out, washed 6 times with deionized water, and then dehydrated 3 times with anhydrous ethanol. The precipitate was dried at 80℃ for 12 h to obtain Ni-Cu co-precipitated precursor powder. NiCuO2 crystals were prepared by calcination at 450℃ for 4 h. After grinding and sieving, Ni-Cu-based coal catalytic gasification catalyst with a particle size less than 120 mesh (<125 μm) was obtained. The specific surface area of ​​this catalyst was measured to be 70.7 m². 2 / g, density is 6.01g / cm³ 3 The yield was 71%.

[0040] The preparation methods of Examples 1 and 2 of this invention are modified coprecipitation methods, which improve the yield of the catalyst, while the preparation method of Comparative Example 1 is a conventional coprecipitation method, and its yield is significantly lower than that of Examples 1 and 2.

[0041] Catalyst performance evaluation

[0042] Taking bituminous coal as an example, the Ni-Cu-based coal catalytic gasification catalyst prepared in Example 1 above, and the Ni and Cu monometallic-based coal catalytic gasification catalyst prepared by the same method, were added to pulverized coal at different mass percentages, and their performance was tested on a fluidized bed test device. Evaluation conditions: atmospheric pressure, gasification temperature 800℃, and CO2 flow rate of the gasifying agent 1.8 L / min. The carbon conversion rates of coal gasification under different amounts of various coal catalytic gasification catalysts are as follows: Figure 1 As shown, the carbon conversion rate of coal gasification gradually increases with the increase of catalyst addition. Furthermore, the catalytic effect of the Ni-Cu-based coal catalytic gasification catalyst is far superior to that of single-metal-based coal catalytic gasification catalysts using Ni and Cu. After adding 4% Ni-Cu-based coal catalytic gasification catalyst, the carbon conversion rate can be increased to 93.2%, proving that this Ni-Cu-based coal catalytic gasification catalyst has excellent catalytic performance. This invention uses bituminous coal as an example to test catalyst performance, but testing with other coal types can also improve the carbon conversion rate, although the increase may differ slightly.

Claims

1. The application of a Ni-Cu-based coal catalytic gasification catalyst in coal catalytic gasification, characterized in that: The catalyst comprises metallic nickel and metallic copper, and its main component is NiCuO2 crystals; the catalyst is prepared by: Step 1: Mix the soluble nickel salt and the soluble copper salt, and dissolve them completely in deionized water to obtain a coprecipitation precursor mixed solution; Step 2: Under stirring, the precursor mixture obtained in Step 1 and sodium hydroxide solution are slowly added dropwise to sodium carbonate solution to form a coprecipitate of Ni and Cu hydroxides. After filtration, washing, dehydration and drying, the coprecipitated precursor powder is obtained. The temperature is maintained at 80 ℃ during the precipitation process, the precipitation time is 20-24 h, and the pH is maintained between 9 and 10 during the precipitation process. Step 3: The coprecipitated precursor powder obtained in Step 2 is calcined to obtain NiCuO2 crystals, which are then ground and sieved to finally obtain Ni-Cu-based coal catalytic gasification catalyst with a particle size of less than 120 mesh.

2. The application according to claim 1, characterized in that: In step one, the soluble nickel salt is one of Ni(NO3)2, NiSO4 or NiCl2; the soluble copper salt is one of Cu(NO3)2, CuSO4 or CuCl2.

3. The application according to claim 1, characterized in that: In step two, the molar ratio of Ni, Cu, and sodium carbonate is controlled to be 10:10:1-2.

4. The application according to claim 1, characterized in that: In step one, the soluble nickel salt and soluble copper salt are mixed in the same molar amount, and the concentrations of Ni and Cu in the resulting mixed solution are both 0.5 mol / L; in step two, the concentration of the sodium carbonate solution is 0.1 mol / L.

5. The application according to claim 1 or 4, characterized in that: In step two, the volume ratio of the precursor mixture solution to the sodium carbonate solution is 2:

1.

6. The application according to claim 1, characterized in that: In step two, after filtration, the product is washed 6 times with deionized water, dehydrated 3 times with anhydrous ethanol, and dried at 80℃ for 10-12 hours.

7. The application according to claim 1, characterized in that: In step three, the calcination temperature is 400-500℃ and the time is 4-5 h.

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