A heterogeneous catalyst for preparing acetonitrile by catalyzing coal-based ethanol amination, and a preparation method and application thereof

Abstract

This invention discloses a heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile. The catalyst comprises a support and a noble metal supported on the support, wherein the noble metal accounts for 0.1-20% of the catalyst by mass. The support is a composite support composed of an oxide of element M1 and an MFI molecular sieve, wherein the oxide of element M1 is titanium dioxide or silicon dioxide. The oxide of element M1 accounts for 0.3-50% of the support by mass. This invention also discloses a method for preparing the catalyst and its application in the amination of coal-based ethanol to acetonitrile. The catalyst exhibits good catalytic activity and stability, high product selectivity in the preparation of acetonitrile, simple separation and purification, and low cost of the raw material coal-based ethanol, making it suitable for large-scale industrial applications.

Description

Technical Field

[0001] This invention belongs to the field of acetonitrile preparation technology, specifically relating to a heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, its preparation method, and its application. Background Technology

[0002] Acetonitrile is a widely used organic chemical raw material. It can be used as a raw material for the synthesis of fine chemicals such as organic synthesis, pharmaceuticals, pesticides, surfactants, and dyes, as well as as a solvent, extractant, or cleaning solvent. These applications require high purity of acetonitrile.

[0003] Research on direct synthesis routes of acetonitrile both domestically and internationally includes the syngas ammoniation method, the acetamide-phosphorus pentoxide dehydration reaction method, the methanol-ammonia reaction, the ethane-ammonia reaction, the propane-ammonia reaction, the acetic acid ammoniation method, the ethanol ammoniation route, and the ethanol dehydrogenation ammoniation method. Among these, the ethanol dehydrogenation ammoniation method for synthesizing acetonitrile has the advantages of high raw material utilization and high added value of by-products. Moreover, the ammoniation reaction is relatively mild and can be carried out in a fixed-bed reactor. Therefore, the ethanol dehydrogenation ammoniation route has a promising future.

[0004] In 1981, Roger et al. of Cyanamid Company disclosed a Cu / Al₂O₃ and Cu-Zn / Al₂O₃ catalyst and a method for catalyzing the synthesis of acetonitrile from ethanol in patent US4654440. At a reaction temperature of 325 °C, the acetonitrile yield reached 87%. Zhang Di et al. of Hebei University of Technology used a Ni-modified Co / γ-Al₂O₃ catalyst, achieving an acetonitrile yield of 92.5% at 420 °C with an alcohol-to-ammonia ratio of 1:4. In 2011, Cao Jinpeng et al. of Northeast Petroleum University reported a supported Cu / γ-Al₂O₃ catalyst, achieving an acetonitrile yield of 92% at a reaction temperature of 290 °C and an alcohol-to-ammonia ratio of 1:7. Zhang Xiaomin of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, disclosed an ethanol ammoniation dehydrogenation catalyst in patents CN202011493756.6 and CN202011493724.6. This catalyst uses ZSM-5 or silica-alumina molecular sieves to support transition metals such as iron, cobalt, nickel, and copper. In its embodiments, the ethanol conversion rate is greater than 90%, and the acetonitrile selectivity can reach 95%. However, these disclosed catalysts all suffer from drawbacks such as easy catalyst deactivation and a high ammonia-to-ethanol ratio.

[0005] The key to the process route of coal-based ethanol dehydrogenation amination to synthesize acetonitrile is the catalytic reaction technology. Coal-based ethanol contains impurities (small amounts of methanol, fusel oil, water and sulfur-containing compounds), and the catalyst needs to meet the stringent requirements of the process conditions: (1) High activity: This is because the separation of ethanol and acetonitrile is difficult. If the single-pass conversion rate is low, it will directly lead to a large energy consumption and large equipment size in the separation process; and coal-based ethanol has more impurities and is more difficult to purify than bioethanol, which affects the conversion of raw materials on the catalyst; (2) High selectivity: Since the reaction temperature is above 300 ℃, the reaction intermediate acetaldehyde is relatively active. If the temperature is too high, a variety of by-products and tar will be generated. Many by-products will cause the separation process to be complicated and reduce the product quality; (3) Not easy to deactivate: The main effective components of traditional amination dehydrogenation catalysts are Cu or Ni, but Cu particles are prone to thermal sintering and deactivation at high temperatures, and water and ammonia are also easy to react with Cu. Therefore, it is necessary to develop a medium-temperature high-efficiency catalyst with good stability suitable for the coal-based ethanol dehydrogenation amination to synthesize acetonitrile. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, its preparation method, and its application. The catalyst has a support that facilitates the dispersion of active metals and improves the mass transfer rate, and exhibits good low-temperature activity and stability for the amination reaction of ethanol.

[0007] A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal supported on the support, wherein the noble metal accounts for 0.1-20% of the mass fraction of the catalyst; the support is a composite support composed of an oxide of element M1 and an MFI molecular sieve, wherein the oxide of element M1 is titanium dioxide or silicon dioxide; wherein the oxide of element M1 accounts for 0.3-50% of the mass fraction of the support.

[0008] Preferably, the precious metal is gold, palladium, rhodium, or ruthenium.

[0009] Preferably, the oxide of element M1 is titanium dioxide; in the carrier, the oxide of element M1 accounts for 0.3-30% of the mass fraction of the carrier.

[0010] The method for preparing the heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile includes the following steps: (1) Preparation of the carrier by hydrothermal synthesis-adsorption hydrolysis method: (1.1) Mix the template agent, aluminum source, alkali source and deionized water evenly; slowly add the silicon source under ice bath conditions of 0-3℃, and then age for 0.5-10 h; (1.2) Transfer to a stainless steel autoclave and crystallize at 70-250℃ for 1-96 h; then filter, wash, dry and calcine to obtain MFI molecular sieve; (1.3) The MFI molecular sieve obtained in step (1.2) is exchanged three times with ammonium chloride solution and then calcined again. The mass of the product after ammonium exchange and calcination is recorded as m1. Then, TiCl4 or SiCl4 vapor is carried by high-purity nitrogen gas and adsorbed at room temperature for 0.1-48 h. After standing in air for 2-3 days, it is calcined again to obtain the support. The support is weighed again using a balance and the mass is recorded as m2. The mass increase of the adsorption step is calculated as Δm = m2 - m1. The mass fraction of titanium dioxide or silicon dioxide in the support can be calculated based on Δm. w =Δm / m2, the carrier is marked as w TiO2-MFI or w SiO2-MFI, for example: 0.5 SiO2-MFI indicates that the mass fraction of silica in the carrier is 50%; (2) Impregnation method for loading precious metals: Prepare an aqueous solution of the noble metal precursor, then mix the support and the aqueous solution of the noble metal precursor, stir and reflux at 40-85°C for 0.5-24 h, then evaporate the solvent at 85-110°C and calcine to obtain the catalyst.

[0011] Preferably, the amount of silicon source is SiO2, the amount of aluminum source is Al2O3, and the molar ratio of silicon source, aluminum source, template agent, alkali source and water is 1:0.01-0.1:0.1-1.2:0.01-0.5:10-1000.

[0012] Preferably, the silicon source is tetraethyl orthosilicate or sodium silicate; the aluminum source is aluminum nitrate, aluminum sulfate, or sodium aluminate; the template agent is tetraalkylammonium hydroxide or tetraalkylammonium halide; and the alkali source is sodium hydroxide.

[0013] Preferably, in the template agent, the alkyl group includes methyl, ethyl, propyl, isopropyl, or butyl, and the ammonium halide includes ammonium chloride, ammonium bromide, or ammonium iodide.

[0014] Preferably, the drying is performed at a constant temperature of 50-110℃ for 1-24 hours; the calcination is performed at 200-660℃ for 1-24 hours.

[0015] A method for catalytic amination of coal-based ethanol to acetonitrile is disclosed, comprising the following steps: A catalyst is loaded into a fixed-bed reactor and reduced in situ under a reducing atmosphere. Then, coal-based ethanol and liquid ammonia are introduced, and an amination reaction occurs under a reducing atmosphere at 180-420℃ and 0.1-3.5 MPa. The product is collected. The molar ratio of coal-based ethanol to liquid ammonia is 1:(1-10), and the mass hourly space velocity (WHSV) of ethanol is 0.1-3.0 h⁻¹. -1 The catalyst is the catalyst described in this invention.

[0016] Preferably, the reducing atmosphere is a mixture of hydrogen and nitrogen or argon, wherein the volume ratio of hydrogen is 3-25%.

[0017] Advantages of this invention: (1) In the catalyst prepared by the present invention, the support has a special bowl-shaped cavity structure, which on the one hand provides a higher specific surface area and surface defect sites, and on the other hand facilitates the timely desorption and diffusion of acetonitrile products in the pores, improves product selectivity and effectively resists carbon deposition. (2) In the catalyst, compared with a single molecular sieve support, the oxide-molecular sieve composite support on the surface of the composite support will generate a support-metal interaction between the oxide and the active component noble metal, which can reduce the agglomeration and sintering of the active metal component and improve the low-temperature activity and stability of the ethanol amination catalyst. (3) The catalyst has good tolerance to water, sulfur and nitrogen impurities in the raw materials in the reaction of ethanol amination to acetonitrile, and can directly use coal-based ethanol as raw material, which reduces the cost; (4) The method has high product selectivity in the preparation of acetonitrile, simple separation and purification, and low cost of raw material coal-based ethanol, making it suitable for large-scale industrial application. Attached Figure Description

[0018] Figure 1 Scanning electron microscope (SEM) images of ZSM-5 molecular sieve and TiO2-MFI support; Figure 2 Transmission electron microscopy (TEM) image of the 0.20TiO2-MFI support. Detailed Implementation

[0019] Example 1 A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal Au supported on the support, wherein the noble metal Au accounts for 0.2% of the mass fraction of the catalyst; the support is a composite support composed of titanium dioxide and MFI molecular sieve, wherein titanium dioxide accounts for 20% of the mass fraction of the support; the catalyst is labeled as 0.2%Au / 0.20TiO2-MFI; The catalyst was prepared by the following method: (1) Preparation of the carrier by hydrothermal synthesis-adsorption hydrolysis method: (1.1) Mix 9.75 mL (12 mmol) of 25% tetrapropylammonium hydroxide, 0.15 g (0.9 mmol as Al2O3), 0.09 g (2.25 mmol) of sodium hydroxide, and 12.8 mL (711.11 mmol) of deionized water and stir well; slowly add 7.95 mL of tetraethyl orthosilicate (35.7 mmol as SiO2) dropwise under ice bath conditions at 0-3℃, and then age for 10 h; (1.2) Transfer to a stainless steel autoclave and crystallize at 160°C for 48 hours; then filter, wash, dry at 110°C for 12 hours, and calcine at 560°C for 4 hours; (1.3) The product obtained in step (1.2) was exchanged three times with 1 mol / L ammonium chloride solution and then calcined at 550℃ for 4 h. 1.43 g of the product after ammonium exchange and calcination was weighed using a balance, and then TiCl4 vapor was carried by high-purity nitrogen (30 mL / min) and adsorbed at room temperature for 15 h. After standing in air for 2-3 days, it was calcined again to obtain the support. The support was weighed again using a balance and the mass was recorded as 1.78 g. The mass increase Δm of the adsorption step was calculated as 0.35 g. The mass fraction of titanium dioxide in the support can be calculated based on Δm. w =0.35 / 1.78, take 0.20, and the carrier is then labeled as 0.20 TiO2-MFI, the mass fraction of titanium dioxide in the support is 0.20; (2) Impregnation method for loading precious metals: Take the above 0.20 1.5 g of TiO2-MFI support was mixed with 5.18 mL of tetrachloroauric acid solution (concentration 0.001 g / mL) and 20 mL of deionized water. The mixture was stirred and refluxed at 85 °C for 5 h. The reflux device was removed, and the solvent was evaporated at 95 °C. The mixture was then calcined at 560 °C for 6 h to obtain the catalyst 0.2% Au / O2. .20 The mass fraction of Au in the TiO2-MFI catalyst is 0.2%.

[0020] Example 2 A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal Au supported on the support, wherein the noble metal Au accounts for 0.2% of the mass fraction of the catalyst; the support is a composite support composed of silica and MFI molecular sieve, wherein the silica accounts for 20% of the mass fraction of the support; the catalyst is labeled as 0.2%Au / 0.2SiO2-MFI; In the preparation of the catalyst, SiCl4 vapor was used instead of TiCl4 vapor, and the rest was the same as in Example 1.

[0021] Example 3 A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal Pd supported on the support, wherein the noble metal Pd accounts for 0.2% of the mass fraction of the catalyst; the support is a composite support composed of TiO2 and MFI molecular sieve, wherein TiO2 accounts for 20% of the mass fraction of the support; the catalyst is labeled as 0.2% Pd / 0.2TiO2-MFI; In the preparation of the catalyst, palladium chloride solution was used instead of tetrachloroauric acid solution, and the rest was the same as in Example 1.

[0022] Example 4 A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal Rh supported on the support, wherein the noble metal Rh accounts for 0.2% of the mass fraction of the catalyst; the support is a composite support composed of TiO2 and MFI molecular sieve, wherein TiO2 accounts for 20% of the mass fraction of the support; the catalyst is labeled as 0.2%Rh / 0.2TiO2-MFI; In the preparation of the catalyst, rhodium chloride solution was used instead of tetrachloroauric acid solution, and the rest was the same as in Example 1.

[0023] Example 5 A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal Ru supported on the support, wherein the noble metal Ru accounts for 0.2% of the mass fraction of the catalyst; the support is a composite support composed of TiO2 and MFI molecular sieve, wherein TiO2 accounts for 20% of the mass fraction of the support; the catalyst is labeled as 0.2%Ru / 0.2TiO2-MFI; In the preparation of the catalyst, ruthenium chloride solution was used instead of tetrachloroauric acid solution, and the rest was the same as in Example 1.

[0024] Example 6 A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal Au supported on the support, wherein the noble metal Au accounts for 20% of the mass fraction of the catalyst; the support is a composite support composed of silica and MFI molecular sieve, wherein the silica accounts for 49% of the mass fraction of the support; the catalyst is labeled as 20%Au / 0.49SiO2-MFI; The catalyst was prepared by the following method: (1) Preparation of the carrier by hydrothermal synthesis-adsorption hydrolysis method: (1.1) Using tetrapropylammonium hydroxide as a template agent, aluminum sulfate as an aluminum source, sodium hydroxide as an alkali source, and sodium silicate as a silicon source, wherein the amount of silicon source is calculated as SiO2 and the amount of aluminum source is calculated as Al2O3, the molar ratio of silicon source, aluminum source, template agent, alkali source, and water is weighed according to 1:0.01:0.1:0.01:10. 25% tetrapropylammonium hydroxide, aluminum sulfate, sodium hydroxide, and deionized water are mixed and stirred evenly. Sodium silicate is slowly added dropwise under ice bath conditions of 0-3℃, and then aged for 0.5 h. (1.2) The mixture was transferred to a stainless steel autoclave and crystallized at 70 °C for 96 h; then filtered, washed, dried at 50 °C for 24 h, and calcined at 200 °C for 24 h to obtain MFI molecular sieve; (1.3) The MFI molecular sieve obtained in step (1.2) was exchanged three times with 1 mol / L ammonium chloride solution, and then calcined at 200 °C for 24 h. The mass of the product was weighed by a balance and found to be 4.5 g. Then, SiCl4 vapor was carried by high-purity nitrogen gas and adsorbed at room temperature for 48 h. After standing in air for 3 days, it was calcined again at 200 °C for 24 h to obtain 8.8 g of support. The mass increase of the adsorption step was calculated by a balance: Δm = 4.3 g. The mass fraction of silica in the support can be calculated based on Δm. w =4.3 / 8.8, take 0.49, and label the support as 0.49SiO2-MFI; (2) Impregnation method for loading precious metals: Take 3.0 g of the support 0.49SiO2-MFI, mix the support, 12.9 mL of tetrachloroauric acid solution (concentration 0.1 g / mL) and 20 mL of deionized water, stir and reflux at 40 °C for 24 h, remove the reflux device and evaporate the solvent at 110 °C, calcine at 200 °C for 24 h to obtain the catalyst 20%Au / 0.49SiO2-MFI.

[0025] Example 7 A heterogeneous catalyst for the amination of coal-based ethanol to acetonitrile, the catalyst comprising a support and a noble metal Au supported on the support, wherein the noble metal Au accounts for 2% of the mass fraction of the catalyst; the support is a composite support composed of titanium dioxide and MFI molecular sieve, wherein the titanium dioxide accounts for 0.3% of the mass fraction of the support; the catalyst is labeled as 2%Au / 0.003TiO2-MFI; The catalyst was prepared by the following method: (1) Preparation of the carrier by hydrothermal synthesis-adsorption hydrolysis method: (1.1) Using tetrapropylammonium hydroxide as a template agent, aluminum nitrate as an aluminum source, sodium hydroxide as an alkali source, and sodium silicate as a silicon source, the amount of the silicon source is calculated as SiO2, and the amount of the aluminum source is calculated as Al2O3. The molar ratio of the silicon source, aluminum source, template agent, alkali source, and water is 1:0.1:1.2:0.5:1000. 25% tetrapropylammonium hydroxide, aluminum sulfate, sodium hydroxide, and deionized water are mixed and stirred evenly. Sodium silicate is slowly added dropwise under ice bath conditions at 0-3℃, and then aged for 5 h. (1.2) Transfer to a stainless steel autoclave and crystallize at 250 °C for 1 h; then filter, wash, dry at 110 °C for 1 h, and calcine at 660 °C for 1 h; (1.3) The product obtained in step (1.2) was exchanged three times with 1 mol / L ammonium chloride solution and then calcined at 660 °C for 1 h. Then, TiCl4 vapor was carried by high-purity nitrogen and adsorbed at room temperature for 30 min. After standing in air for 3 days, it was calcined again at 660 °C for 1 h to obtain the support, which was labeled as 0.003TiO2-MFI. (2) Impregnation method for loading precious metals: Take 3.0 g of the support TiO2-MFI, mix the support, 10.56 mL of tetrachloroauric acid solution (concentration 0.01 g / mL) and 20 mL of deionized water, stir and reflux at 60 °C for 24 h, remove the reflux device and evaporate the solvent at 110 °C, calcine at 660 °C for 1 h to obtain the catalyst 2% Au / 0.003 TiO2-MFI.

[0026] Comparative Example 1 Commercially available TiO2 was used instead of the carrier TiO2-MFI in Example 1, and everything else was the same as in Example 1.

[0027] Comparative Example 2 Commercially available SiO2 was used instead of the carrier TiO2-MFI in Example 1, and everything else was the same as in Example 1.

[0028] Comparative Example 3 MFI molecular sieves were used directly without adsorption of TiCl4 vapor. That is, when preparing the support in step (1), step (1.3) was to exchange the product obtained in step (1.2) with 1 mol / L ammonium chloride solution three times and then calcine it at 550℃ for 4 h. The rest was the same as in Example 1.

[0029] 1. Morphology inspection Scanning electron microscopy was performed on commercially available ZSM-5 molecular sieve with a silicon-to-aluminum ratio (SiO2 / Al2O3) of 40 and the 0.20TiO2-MFI support obtained in Example 1. (See attached image.) Figure 1 ;in, Figure 1Images a and b in the image are scanning electron microscope (SEM) images of ZSM-5 molecular sieve. Figure 1 Images c and d are scanning electron microscope (SEM) images of TiO2-MFI. The SEM images show that the commercially available ZSM-5 molecular sieve has a hexagonal prism morphology with twins, and the long axis of the grains is approximately 450-550 nm. The 0.2 TiO2-MFI support consists of hexagonal prism particles with a circular opening on one side, containing semi-open pores (empty bowl-shaped), and a larger particle size (long axis of the grains is approximately 900-1000 nm). Transmission electron microscopy was performed on the 0.20TiO2-MFI support obtained in Example 1. The results are shown in [Figure 1]. Figure 2 a and b; by Figure 2 It can be seen that the 0.20TiO2-MFI support has a special bowl-shaped cavity structure. The internal space of the U-shaped pores of the grains is cylindrical, with a cavity cross-sectional diameter of 400-500 nm and an outer shell wall thickness of 100-250 nm.

[0030] Therefore, it can be seen that the 0.2TiO2-MFI support obtained in Example 1 of the present invention has a bowl-shaped hollow shell structure.

[0031] 2. Catalytic performance testing The catalyst was loaded into a fixed-bed reactor and reduced at 300°C for 4 h under a 5% H₂ / Ar atmosphere. Then, coal-based ethanol and liquid ammonia were introduced, and an ammoniation reaction occurred under the same reducing atmosphere at 180-420°C and 0.1-3.5 MPa. The products were collected. The molar ratio of coal-based ethanol to liquid ammonia was 1:(1-10), and the mass hourly space velocity (WHSV) of ethanol was 0.1-3.0 h⁻¹. -1 The coal-based ethanol contained the following impurities: methanol and other fusel oils <0.32% (volume fraction), water <0.63% (volume fraction), sulfur <1 mg / kg, chlorine <1.9 g / L, and iron <2 mg / kg. The reaction products were quantitatively analyzed by gas chromatography (GC). The chromatographic model was Thermo Fisher Trace 1310, the column was TR-WAX 60m*0.32mm*1.0μm, and an FID detector was used. The reaction conditions and results for different catalysts are shown in Table 1. Table 1. Reaction conditions and results for different catalysts .

[0032] 3. Stability Testing Based on the above catalytic performance tests, the reaction results of the catalyst in Example 1 were examined at different reaction times. The reaction conditions were 290℃, 1.0 MPa, 8% H2 / Ar, alcohol-to-amine ratio of 1:5, and ethanol space velocity of 1.0 h⁻¹. -1 The results are shown in Table 2.

[0033] Table 2. Reaction results at different times 。

Claims

1. A method for catalytic amination of coal-based ethanol to acetonitrile, characterized in that: The catalyst was loaded into a fixed-bed reactor and reduced in situ under a reducing atmosphere. Then, coal-based ethanol and liquid ammonia were introduced, and an ammoniation reaction occurred under a reducing atmosphere at 180-420℃ and 0.1-3.5 MPa. The products were collected. The molar ratio of coal-based ethanol to liquid ammonia was 1:(1-10), and the mass hourly space velocity (WHSV) of ethanol was 0.1-3.0 h⁻¹. -1 The catalyst includes a support and a noble metal supported on the support, wherein the noble metal accounts for 0.1-20% of the mass fraction of the catalyst; the support is a composite support composed of an oxide of element M1 and an MFI molecular sieve, wherein the oxide of element M1 is titanium dioxide or silicon dioxide; wherein the oxide of element M1 accounts for 0.3-50% of the mass fraction of the support.

2. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 1, characterized in that: The precious metal is gold, palladium, rhodium, or ruthenium.

3. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 2, characterized in that: The oxide of element M1 is titanium dioxide; in the carrier, the oxide of element M1 accounts for 0.3-30% of the mass fraction of the carrier.

4. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 1, characterized in that: The catalyst was prepared by the following method: (1) The carrier was prepared by hydrothermal synthesis-adsorption hydrolysis method: (1.1) Mix the template agent, aluminum source, alkali source and deionized water evenly; slowly add the silicon source under ice bath conditions of 0-3℃, and then age for 0.5-10 h; (1.2) Transfer to a stainless steel autoclave and crystallize at 70-250℃ for 1-96 h; then filter, wash, dry and calcine to obtain MFI molecular sieve; (1.3) The MFI molecular sieve obtained in step (1.2) is exchanged with ammonium chloride solution three times and then calcined again. Then, TiCl4 or SiCl4 vapor is carried by high-purity nitrogen gas and adsorbed at room temperature for 0.1-48 h. Then, it is left to stand in air for 2-3 days and calcined again to obtain the support. (2) Impregnation method for loading precious metals: Prepare an aqueous solution of the noble metal precursor, then mix the support and the aqueous solution of the noble metal precursor, stir and reflux at 40-85°C for 0.5-24 h, then evaporate the solvent at 85-110°C and calcine to obtain the catalyst.

5. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 4, characterized in that: The amount of silicon source is SiO2, the amount of aluminum source is Al2O3, and the molar ratio of silicon source, aluminum source, template agent, alkali source and water is 1:0.01-0.1:0.1-1.2:0.01-0.5:10-1000.

6. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 5, characterized in that: The silicon source is tetraethyl orthosilicate or sodium silicate; the aluminum source is aluminum nitrate, aluminum sulfate, or sodium aluminate; the template agent is tetraalkylammonium hydroxide or tetraalkylammonium halide; and the alkali source is sodium hydroxide.

7. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 6, characterized in that: In the template agent, the alkyl group includes methyl, ethyl, propyl, isopropyl, or butyl, and the ammonium halide includes ammonium chloride, ammonium bromide, or ammonium iodide.

8. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 4, characterized in that: The drying process involves constant temperature drying at 50-110℃ for 1-24 hours; the calcination process involves calcination at 200-660℃ for 1-24 hours.

9. The method for producing acetonitrile by catalytic amination of coal-based ethanol according to claim 1, characterized in that: The reducing atmosphere is a mixture of hydrogen and nitrogen or argon, wherein hydrogen accounts for 3-25% of the volume.

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