A catalyst application process for producing high-purity benzene based on hydrofining

Abstract

This invention relates to the field of high-purity benzene production technology, and in particular to a catalyst application process for producing high-purity benzene based on hydrorefining. Using crude benzene as raw material, and Co-Mo / γ-Al₂O₃-La₂O₃ as the hydrogenation catalyst, high-purity benzene is obtained through raw material pretreatment, staged hydrogenation reaction, and product separation and refining. Through steps such as support pretreatment, staged impregnation, staged calcination, and staged reduction, combined with optimized process parameters, the La₂O₃ promoter is uniformly dispersed on the support surface, forming a synergistic effect with the Co and Mo dual active components. This significantly improves the catalyst's hydrogenation activity, anti-carbon deposition performance, and thermal stability, solving the problems of insufficient activity and short service life of traditional catalysts.

Description

Technical Field

[0001] This invention relates to the field of high-purity benzene production technology, and in particular to a catalyst application process for the production of high-purity benzene based on hydrorefining. Background Technology

[0002] High-purity benzene (purity ≥ 99.99%) is an important basic organic chemical raw material, widely used in synthetic resins, synthetic fibers, synthetic rubber, pharmaceuticals, pesticides, dyes, and fine chemicals. Its quality directly affects the performance of downstream products. Currently, the main raw material for high-purity benzene production is crude benzene, a byproduct of the coking and petroleum refining industries. Its main components include aromatic hydrocarbons such as benzene, toluene, and xylene, as well as heteroatom compounds such as sulfur, nitrogen, and oxygen, and unsaturated hydrocarbon impurities such as olefins and alkynes. These impurities severely affect the purity and application performance of benzene, thus requiring refining of crude benzene.

[0003] Hydrogenation refining is currently the mainstream process for producing high-purity benzene from crude benzene. This process removes unsaturated hydrocarbons and heteroatom impurities from crude benzene through hydrogenation reactions. It has advantages such as high processing efficiency, good product quality, and environmental friendliness. The hydrogenation catalyst is the core of this process, and its performance directly determines the effect of the hydrogenation reaction, product purity, and process economy.

[0004] Currently, the commonly used catalysts for the hydrogenation refining of crude benzene are mainly Co-Mo and Ni-Mo supported catalysts, with γ-Al₂O₃ being the most common support. γ-Al₂O₃ has the characteristics of large specific surface area, excellent pore structure, and high mechanical strength, which can provide a good support basis for the active components. However, traditional Co-Mo / γ-Al₂O₃ catalysts suffer from problems such as poor dispersion of active components, insufficient hydrogenation activity, weak resistance to carbon deposition, and short service life. When dealing with trace heteroatom impurities in crude benzene, it is difficult to achieve the production requirements of high-purity benzene, and the reaction process requires high temperature and pressure, resulting in high energy consumption. Summary of the Invention

[0005] In view of the deficiencies mentioned in the background art, the present invention provides a catalyst application process for the production of high-purity benzene based on hydrorefining, which achieves efficient and stable production of high-purity benzene while reducing energy consumption and production costs.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: a catalyst application process for the production of high-purity benzene based on hydrogenation refining, using crude benzene as raw material and Co-Mo / γ-Al2O3-La2O3 as hydrogenation catalyst, through raw material pretreatment, staged hydrogenation reaction, and product separation and refining to obtain high-purity benzene; the preparation process of the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst includes the following steps: S1. Take γ-Al2O3 support, crush and sieve it to an average particle size of 35 mesh, place it in a muffle furnace, calcine it at 500℃ for 2 hours, cool it to room temperature, soak it in a dilute nitric acid solution with a mass concentration of 1-3% for 1 hour, filter it, wash it with water until neutral, and dry it at 100℃ for 4 hours to obtain the pretreated γ-Al2O3 support. S2. Dissolve La2O3 in nitric acid solution to prepare a La(NO3)3 impregnation solution with a mass concentration of 5-10%. Immerse the pretreated γ-Al2O3 support in the La(NO3)3 impregnation solution at a liquid-solid ratio of 1-2:1. Immerse at 35°C for 8 hours and then dry at 110°C for 6 hours to obtain the γ-Al2O3 support loaded with La2O3. S3, mix Co(NO3)2·6H2O and (NH4)6Mo7O 24 • 4H2O was dissolved in deionized water to prepare a mixed impregnation solution. The γ-Al2O3 support loaded with La2O3 was immersed in the above mixed impregnation solution at a liquid-to-solid ratio of 1.2 to 2.2:1. The impregnation was carried out at a constant temperature of 35°C for 10 hours to obtain the impregnated catalyst precursor. S4. Place the impregnated catalyst precursor in a muffle furnace, first heat it to 200°C at a heating rate of 2-5°C / min, hold it at that temperature for 1 hour, then heat it to 450°C at a heating rate of 3-6°C / min, hold it at that temperature for 3 hours, and then cool it naturally to room temperature to obtain the calcined catalyst. S5. Place the calcined catalyst in a reduction furnace, introduce a hydrogen-nitrogen mixed reducing gas, and heat it to 300℃ at a heating rate of 2-4℃ / min. Hold the temperature for 4 hours, then heat it to 450℃ and hold it for 4 hours. After the reduction is completed, introduce nitrogen gas to cool it to room temperature, seal it and store it to obtain the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst.

[0007] As a further improvement of the present invention, the mass concentration of Co in the mixed impregnation solution is 2-5%, and the mass concentration of Mo is 8-12%.

[0008] As a further improvement of the present invention, the volume fraction of hydrogen in the mixed reducing gas is 10-20%.

[0009] As a further improvement of the present invention, the raw material pretreatment includes sequentially filtering, removing impurities, and dehydrating the crude benzene raw material; Impurity removal was performed using an adsorption column. The adsorbent was a mixture of activated alumina and molecular sieve in a mass ratio of 2:1. The adsorption temperature was 25℃, and the space velocity was 1.5 h⁻¹. -1 ; Dehydration is performed using a molecular sieve dehydration tower with a molecular sieve type of 3A or 4A, at a dehydration temperature of 35℃ and a space velocity of 2 h⁻¹. -1The moisture in the crude benzene is removed, so that the moisture content of the pretreated crude benzene is ≤50ppm, the sulfur content is ≤1ppm, and the nitrogen content is ≤0.5ppm.

[0010] As a further improvement of the present invention, the staged hydrogenation reaction includes a pre-hydrogenation reaction and a main hydrogenation reaction, both of which are carried out in a fixed-bed reactor filled with a Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst.

[0011] As a further improvement of the present invention, the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst is filled to 80% of the effective height of the reactor, and an axial flow bed is used inside the reactor.

[0012] As a further improvement of the present invention, the pre-hydrogenation reaction process includes: mixing pretreated crude benzene with hydrogen gas at a volume ratio of 50:1, preheating to 180°C, and introducing the mixture into a pre-hydrogenation reactor at a reaction pressure of 1.5 MPa and a liquid hourly space velocity of 3 h⁻¹. -1 The reaction temperature is 200℃.

[0013] As a further improvement of the present invention, the process of the main hydrogenation reaction includes: preheating the product after the pre-hydrogenation reaction to 320°C, and then introducing it into the main hydrogenation reactor at a reaction pressure of 3.5 MPa and a liquid hourly space velocity of 2 h⁻¹. -1 The reaction temperature was 300℃, and the volume ratio of hydrogen to product was 80:1, resulting in the hydrogenated product.

[0014] As a further improvement of the present invention, the product separation and purification step is specifically as follows: (1) The product after the staged hydrogenation reaction is sent to a gas-liquid separator. Under a pressure of 0.5 MPa and a temperature of 60 °C, unreacted hydrogen and light gas are separated. The unreacted hydrogen is purified and then recycled to the hydrogenation reaction step for reuse. (2) The liquid product after gas-liquid separation is sent to the light component removal tower. The bottom temperature of the tower is 120℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 2:1, and the light component by-product is obtained at the top of the tower. (3) The bottom product of the light component removal tower is fed into the heavy component removal tower. The bottom temperature is 140℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 3:1, and the heavy component by-product is obtained at the bottom of the tower. (4) The top product of the de-heavy tower is sent to the distillation tower and a continuous distillation method is adopted. The bottom temperature is 110℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 5:1, the distillation time is 8h, the high purity benzene product is collected from the top of the tower, and the bottom product is recycled to the de-heavy tower for repeated treatment.

[0015] After adopting the above technical solution, the beneficial effects of the present invention are: Through steps such as support pretreatment, segmented impregnation, segmented calcination, and segmented reduction, combined with optimized process parameters, the La2O3 promoter is uniformly dispersed on the support surface, forming a synergistic effect with the Co and Mo dual active components. This significantly improves the hydrogenation activity, anti-carbon deposition performance, and thermal stability of the catalyst, solving the problems of insufficient activity and short service life of traditional catalysts. Detailed Implementation

[0016] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0017] Example 1 This embodiment provides a synthesis process using Co-Mo / γ-Al2O3-La2O3 as a hydrogenation catalyst. The specific preparation steps and technical details are as follows.

[0018] Carrier pretreatment Take a specific surface area of ​​200m² 2 / g, pore volume 0.6cm 3 / g of γ-Al2O3 support was crushed and sieved to an average particle size of 35 mesh, placed in a muffle furnace, calcined at 500℃ for 2h, cooled to room temperature, soaked in a 1% dilute nitric acid solution for 1h, filtered, washed with water until neutral, and dried at 100℃ for 4h to obtain the pretreated γ-Al2O3 support.

[0019] Pretreatment exposes more loadable sites, providing more attachment points for active components and improving the dispersion of active metals.

[0020] Additive loading La2O3 was dissolved in nitric acid solution to prepare a 5% (w / w) La(NO3)3 impregnation solution. The pretreated γ-Al2O3 support was immersed in the La(NO3)3 impregnation solution at a liquid-to-solid ratio of 1:1 and impregnated at 35°C for 8 hours. Then it was dried at 110°C for 6 hours to obtain the γ-Al2O3 support loaded with La2O3.

[0021] La2O3 is uniformly dispersed on the support surface, which can modulate the acidity and alkalinity of the support surface, reduce strong acid centers, avoid excessive hydrogenolysis, and promote better dispersion and reduction of subsequent active components through the electronic effect provided by La.

[0022] Meanwhile, La2O3 is a basic oxide that can neutralize the strong acid centers on the surface of γ-Al2O3. These strong acid centers are the main sites for olefin polymerization, aromatic condensation, and coking. After loading with the additive, it can reduce the formation of carbon precursors and significantly inhibit carbon deposition.

[0023] Active component loading Co(NO3)2·6H2O (cobalt nitrate hexahydrate) and (NH4)6Mo7O 24 • 4H2O (ammonium molybdate tetrahydrate) was dissolved in deionized water to prepare a mixed impregnation solution, wherein the mass concentration of Co was 2% and the mass concentration of Mo was 8%. The γ-Al2O3 support loaded with La2O3 was immersed in the above mixed impregnation solution at a solid-liquid ratio of 1.2:1 and impregnated at 35°C for 10 h to obtain the impregnated catalyst precursor.

[0024] Calcination The impregnated catalyst precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 2–5°C / min, held at that temperature for 1 hour, and then heated to 450°C at a heating rate of 3–6°C / min, held at that temperature for 3 hours, and then naturally cooled to room temperature to obtain the calcined catalyst.

[0025] Reduction and Activation The calcined catalyst was placed in a reduction furnace, and a hydrogen-nitrogen mixed reducing gas was introduced, with a hydrogen volume fraction of 10%. The temperature was increased to 300℃ at a rate of 2–4℃ / min and held for 4 hours. Then, the temperature was increased to 450℃ and held for 4 hours. After reduction, nitrogen gas was introduced to cool the catalyst to room temperature, and it was sealed and stored to obtain the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst.

[0026] Example 2 This embodiment provides a synthesis process using Co-Mo / γ-Al2O3-La2O3 as a hydrogenation catalyst. The specific preparation steps and technical details are as follows.

[0027] Carrier pretreatment Take a specific surface area of ​​200m² 2 / g, pore volume 0.6cm 3 / g of γ-Al2O3 support was crushed and sieved to an average particle size of 35 mesh, placed in a muffle furnace, calcined at 500℃ for 2h, cooled to room temperature, soaked in a 2% dilute nitric acid solution for 1h, filtered, washed with water until neutral, and dried at 100℃ for 4h to obtain the pretreated γ-Al2O3 support.

[0028] Additive loading La2O3 was dissolved in nitric acid solution to prepare a 6% (w / w) La(NO3)3 impregnation solution. The pretreated γ-Al2O3 support was immersed in the La(NO3)3 impregnation solution at a liquid-to-solid ratio of 1.5:1. The solution was kept at 35°C for 8 hours and then dried at 110°C for 6 hours to obtain the γ-Al2O3 support loaded with La2O3.

[0029] Active component loading Co(NO3)2·6H2O (cobalt nitrate hexahydrate) and (NH4)6Mo7O 24 • 4H2O (ammonium molybdate tetrahydrate) was dissolved in deionized water to prepare a mixed impregnation solution, wherein the mass concentration of Co was 3.5% and the mass concentration of Mo was 10%. The γ-Al2O3 support loaded with La2O3 was immersed in the above mixed impregnation solution at a solid-liquid ratio of 2:1 and impregnated at 35°C for 10 h to obtain the impregnated catalyst precursor.

[0030] Calcination The impregnated catalyst precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 2–5°C / min, held at that temperature for 1 hour, and then heated to 450°C at a heating rate of 3–6°C / min, held at that temperature for 3 hours, and then naturally cooled to room temperature to obtain the calcined catalyst.

[0031] Reduction and Activation The calcined catalyst was placed in a reduction furnace, and a hydrogen-nitrogen mixed reducing gas was introduced, with a hydrogen volume fraction of 15%. The temperature was increased to 300℃ at a rate of 2–4℃ / min and held for 4 hours. Then, the temperature was increased to 450℃ and held for 4 hours. After reduction, nitrogen gas was introduced to cool the catalyst to room temperature, and it was sealed and stored to obtain the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst.

[0032] Example 3 This embodiment provides a synthesis process using Co-Mo / γ-Al2O3-La2O3 as a hydrogenation catalyst. The specific preparation steps and technical details are as follows.

[0033] Carrier pretreatment Take a specific surface area of ​​200m² 2 / g, pore volume 0.6cm 3 / g of γ-Al2O3 support was crushed and sieved to an average particle size of 35 mesh, placed in a muffle furnace, calcined at 500℃ for 2h, cooled to room temperature, soaked in a 3% dilute nitric acid solution for 1h, filtered, washed with water until neutral, and dried at 100℃ for 4h to obtain the pretreated γ-Al2O3 support.

[0034] Additive loading La2O3 was dissolved in nitric acid solution to prepare a 10% (w / w) La(NO3)3 impregnation solution. The pretreated γ-Al2O3 support was immersed in the La(NO3)3 impregnation solution at a liquid-to-solid ratio of 2:1 and impregnated at 35°C for 8 hours. Then it was dried at 110°C for 6 hours to obtain the γ-Al2O3 support loaded with La2O3.

[0035] Active component loading Co(NO3)2·6H2O (cobalt nitrate hexahydrate) and (NH4)6Mo7O 24 • 4H2O (ammonium molybdate tetrahydrate) was dissolved in deionized water to prepare a mixed impregnation solution, wherein the mass concentration of Co was 5% and the mass concentration of Mo was 12%. The γ-Al2O3 support loaded with La2O3 was immersed in the above mixed impregnation solution at a solid-liquid ratio of 2.2:1 and impregnated at 35°C for 10 h to obtain the impregnated catalyst precursor.

[0036] Calcination The impregnated catalyst precursor was placed in a muffle furnace and heated to 200°C at a heating rate of 2–5°C / min, held at that temperature for 1 hour, and then heated to 450°C at a heating rate of 3–6°C / min, held at that temperature for 3 hours, and then naturally cooled to room temperature to obtain the calcined catalyst.

[0037] Reduction and Activation The calcined catalyst was placed in a reduction furnace, and a hydrogen-nitrogen mixed reducing gas was introduced, with a hydrogen volume fraction of 20%. The temperature was increased to 300℃ at a rate of 2–4℃ / min and held for 4 hours. Then, the temperature was increased to 450℃ and held for 4 hours. After reduction, nitrogen gas was introduced to cool the catalyst to room temperature, and it was sealed and stored to obtain the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst.

[0038] Three reactors were prepared, each loaded with the Co-Mo / γ-Al₂O₃-La₂O₃ hydrogenation catalyst prepared in Examples 1-3. The catalyst loading height was 80% of the effective height of the reactor, and an axial flow bed was used inside the reactor. High-purity benzene was obtained by sequentially pretreating the raw material, performing staged hydrogenation reaction, and separating and purifying the product.

[0039] The crude benzene feedstock was fed into a precision filter (filtration accuracy 0.3 μm, pressure 0.3 MPa, temperature 30 °C) to remove solid impurities. The filtered crude benzene was then fed into an adsorption column filled with a mixture of activated alumina and molecular sieves at a mass ratio of 2:1. The adsorption temperature was controlled at 25 °C, and the space velocity was 1.5 h⁻¹. -1 The process removes sulfur, nitrogen, and oxygen impurities from the crude benzene. Finally, the purified crude benzene is fed into a molecular sieve dehydration tower (molecular sieve type 3A or 4A), where the dehydration temperature is 35℃ and the space velocity is 2h. -1Remove moisture from crude benzene.

[0040] After pretreatment of the raw materials, the moisture content of the crude benzene is ≤50ppm, the sulfur content is ≤1ppm, and the nitrogen content is ≤0.5ppm, which meets the requirements of the subsequent hydrogenation reaction.

[0041] The staged hydrogenation reaction includes a pre-hydrogenation reaction and a main hydrogenation reaction, both of which are carried out in a reactor.

[0042] The pre-hydrogenation reaction process includes: mixing pretreated crude benzene with hydrogen gas at a volume ratio of 50:1, preheating to 180°C, and then introducing the mixture into the pre-hydrogenation reactor at a reaction pressure of 1.5 MPa and a liquid hourly space velocity of 3 h⁻¹. -1 The reaction temperature is 200℃.

[0043] The main hydrogenation reaction process includes: preheating the product from the pre-hydrogenation reaction to 320°C, then introducing it into the main hydrogenation reactor at a reaction pressure of 3.5 MPa and a liquid hourly space velocity of 2 h⁻¹. -1 The reaction temperature was 300℃, and the volume ratio of hydrogen to product was 80:1, resulting in the hydrogenated product.

[0044] The hydrogenation product is subjected to gas-liquid separation, removal of light components, removal of heavy components, and distillation purification in sequence, as follows: (1) The product after the staged hydrogenation reaction is sent to a gas-liquid separator. Under a pressure of 0.5 MPa and a temperature of 60 °C, unreacted hydrogen and light gas are separated. The unreacted hydrogen is purified and then recycled to the hydrogenation reaction step for reuse. Impurities such as hydrogen sulfide and ammonia are washed and absorbed by alkaline washing before being discharged.

[0045] (2) The liquid product after gas-liquid separation is sent to the light component removal tower. The bottom temperature of the tower is 120℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 2:1, and the light component by-product is obtained at the top of the tower. (3) The bottom product of the light component removal tower is fed into the heavy component removal tower. The bottom temperature is 140℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 3:1, and the heavy component by-product is obtained at the bottom of the tower. (4) The top product of the de-heavy tower is sent to the distillation tower and a continuous distillation method is adopted. The bottom temperature is 110℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 5:1, the distillation time is 8h, the high purity benzene product is collected from the top of the tower, and the bottom product is recycled to the de-heavy tower for repeated treatment.

[0046] Using the catalyst prepared in Example 1, the high-purity benzene product obtained had a purity of 99.993%, a sulfur content of 0.08 ppm, a nitrogen content of 0.04 ppm, a moisture content of 8 ppm, and a high-purity benzene yield of 95.3%.

[0047] Using the catalyst prepared in Example 2, the high-purity benzene product obtained had a purity of 99.995%, a sulfur content of 0.06 ppm, a nitrogen content of 0.03 ppm, a moisture content of 7 ppm, and a high-purity benzene yield of 96.1%.

[0048] Using the catalyst prepared in Example 3, the high-purity benzene product obtained had a purity of 99.997%, a sulfur content of 0.04 ppm, a nitrogen content of 0.01 ppm, a moisture content of 5 ppm, and a high-purity benzene yield of 96.2%.

[0049] This invention increases the specific surface area and pore volume, and optimizes the surface properties of a γ-Al₂O₃ support through high-temperature calcination and dilute nitric acid activation pretreatment. A stepwise impregnation method is used to first introduce La₂O₃ as a promoter, followed by loading Co and Mo dual active components. Combined with segmented calcination and reduction processes, La₂O₃ is uniformly dispersed on the support surface and forms a strong interaction with the active components. La₂O₃ can regulate the acidity and alkalinity of the support surface, inhibit high-temperature phase transformation and metal sintering, reduce carbon deposition at the source, and improve structural thermal stability. Simultaneously, through electronic and structural effects, it promotes high dispersion and complete reduction of the active phase, significantly improving the catalyst's hydrodesulfurization, hydrodenitrogenation, and olefin saturation activity. Combined with raw material pretreatment and staged hydrogenation reaction processes, the final result is a catalyst with high hydrogenation activity, strong resistance to carbon deposition, good thermal stability, and long service life.

[0050] The embodiments described above are not exhaustive and do not limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the above description. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A catalyst application process for the production of high-purity benzene based on hydrorefining, characterized in that, High-purity benzene was obtained by using crude benzene as raw material and Co-Mo / γ-Al2O3-La2O3 as hydrogenation catalyst, through raw material pretreatment, staged hydrogenation reaction, and product separation and purification. The preparation process of the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst includes the following steps: S1. Take γ-Al2O3 support, crush and sieve it to an average particle size of 35 mesh, place it in a muffle furnace, calcine it at 500℃ for 2 hours, cool it to room temperature, soak it in a dilute nitric acid solution with a mass concentration of 1-3% for 1 hour, filter it, wash it with water until neutral, and dry it at 100℃ for 4 hours to obtain the pretreated γ-Al2O3 support. S2. Dissolve La2O3 in nitric acid solution to prepare a La(NO3)3 impregnation solution with a mass concentration of 5-10%. Immerse the pretreated γ-Al2O3 support in the La(NO3)3 impregnation solution at a liquid-solid ratio of 1-2:

1. Immerse at 35°C for 8 hours and then dry at 110°C for 6 hours to obtain the γ-Al2O3 support loaded with La2O3. S3, mix Co(NO3)2·6H2O and (NH4)6Mo7O 24 • 4H2O was dissolved in deionized water to prepare a mixed impregnation solution. The γ-Al2O3 support loaded with La2O3 was immersed in the above mixed impregnation solution at a liquid-to-solid ratio of 1.2 to 2.2:

1. The impregnation was carried out at a constant temperature of 35°C for 10 hours to obtain the impregnated catalyst precursor. S4. Place the impregnated catalyst precursor in a muffle furnace, first heat it to 200°C at a heating rate of 2-5°C / min, hold it at that temperature for 1 hour, then heat it to 450°C at a heating rate of 3-6°C / min, hold it at that temperature for 3 hours, and then cool it naturally to room temperature to obtain the calcined catalyst. S5. Place the calcined catalyst in a reduction furnace, introduce a hydrogen-nitrogen mixed reducing gas, and heat it to 300℃ at a heating rate of 2-4℃ / min. Hold the temperature for 4 hours, then heat it to 450℃ and hold it for 4 hours. After the reduction is completed, introduce nitrogen gas to cool it to room temperature, seal it and store it to obtain the Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst.

2. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 1, characterized in that: The mass concentration of Co in the mixed impregnation solution is 2-5%, and the mass concentration of Mo is 8-12%.

3. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 1, characterized in that: The volume fraction of hydrogen in the mixed reducing gas is 10-20%.

4. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 1, characterized in that, The raw material pretreatment includes sequentially filtering, removing impurities, and dehydrating the crude benzene raw material. Impurity removal was performed using an adsorption column. The adsorbent was a mixture of activated alumina and molecular sieve in a mass ratio of 2:

1. The adsorption temperature was 25℃, and the space velocity was 1.5 h⁻¹. -1 ; Dehydration is performed using a molecular sieve dehydration tower with a molecular sieve type of 3A or 4A, at a dehydration temperature of 35℃ and a space velocity of 2 h⁻¹. -1 The moisture in the crude benzene is removed, so that the moisture content of the pretreated crude benzene is ≤50ppm, the sulfur content is ≤1ppm, and the nitrogen content is ≤0.5ppm.

5. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 1, characterized in that: The staged hydrogenation reaction includes a pre-hydrogenation reaction and a main hydrogenation reaction, both of which are carried out in a fixed-bed reactor filled with a Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst.

6. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 5, characterized in that: The Co-Mo / γ-Al2O3-La2O3 hydrogenation catalyst is filled to 80% of the effective height of the reactor, and an axial flow bed is used inside the reactor.

7. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 6, characterized in that, The pre-hydrogenation reaction process includes: mixing pretreated crude benzene with hydrogen gas at a volume ratio of 50:1, preheating to 180°C, and introducing the mixture into a pre-hydrogenation reactor at a reaction pressure of 1.5 MPa and a liquid hourly space velocity of 3 h⁻¹. -1 The reaction temperature is 200℃.

8. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 7, characterized in that, The main hydrogenation reaction process includes: preheating the product from the pre-hydrogenation reaction to 320°C, and then introducing it into the main hydrogenation reactor at a reaction pressure of 3.5 MPa and a liquid hourly space velocity of 2 h⁻¹. -1 The reaction temperature was 300℃, and the volume ratio of hydrogen to product was 80:1, resulting in the hydrogenated product.

9. The catalyst application process for producing high-purity benzene based on hydrorefining according to claim 1, characterized in that, The product separation and purification steps are specifically as follows: (1) The product after the staged hydrogenation reaction is sent to a gas-liquid separator. Under a pressure of 0.5 MPa and a temperature of 60 °C, unreacted hydrogen and light gas are separated. The unreacted hydrogen is purified and then recycled to the hydrogenation reaction step for reuse. (2) The liquid product after gas-liquid separation is sent to the light component removal tower. The bottom temperature of the tower is 120℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 2:1, and the light component by-product is obtained at the top of the tower. (3) The bottom product of the light component removal tower is fed into the heavy component removal tower. The bottom temperature is 140℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 3:1, and the heavy component by-product is obtained at the bottom of the tower. (4) The top product of the de-heavy tower is sent to the distillation tower and a continuous distillation method is adopted. The bottom temperature is 110℃, the top temperature is 80℃, the top pressure is 0.1MPa, the reflux ratio is 5:1, the distillation time is 8h, the high purity benzene product is collected from the top of the tower, and the bottom product is recycled to the de-heavy tower for repeated treatment.