阅读说明：本技术 一种加氢脱氮催化剂的制备方法 (Preparation method of hydrodenitrogenation catalyst ) 是由 隋宝宽 季洪海 彭冲 吕振辉 于 2019-04-17 设计创作，主要内容包括：本发明公开了一种加氢脱氮催化剂的制备方法。该方法包括：(1)依次用铝盐溶液和含第一活性金属组分溶液浸渍物理扩孔剂,并干燥、焙烧制得改性物理扩孔剂；(2)将步骤(1)所得改性物理扩孔剂、拟薄水铝石混捏成型、干燥、焙烧,得到中间体；(3)将步骤(2)所得的中间体浸入碳酸氢铵溶液中,然后密封热处理,再经干燥、焙烧制得改性氧化铝基载体；(4)将含第二活性金属组分溶液浸渍步骤(3)所得的改性氧化铝基载体,干燥、焙烧制得加氢脱氮催化剂。该方法制备的催化剂具有较高的加氢脱氮能力和加氢脱残炭能力,该催化剂适用于渣油加氢领域。(The invention discloses a preparation method of a hydrodenitrogenation catalyst. The method comprises the following steps: (1) sequentially dipping the physical pore-enlarging agent by using an aluminum salt solution and a solution containing a first active metal component, drying and roasting to obtain a modified physical pore-enlarging agent; (2) kneading the modified physical pore-expanding agent obtained in the step (1) and pseudo-boehmite, molding, drying and roasting to obtain an intermediate; (3) immersing the intermediate obtained in the step (2) into an ammonium bicarbonate solution, then carrying out sealing heat treatment, drying and roasting to obtain a modified alumina-based carrier; (4) and (3) dipping the modified alumina-based carrier obtained in the step (3) in a solution containing a second active metal component, drying and roasting to obtain the hydrodenitrogenation catalyst. The catalyst prepared by the method has high hydrodenitrogenation capacity and hydrodecarbonization capacity, and is suitable for the field of residual oil hydrogenation.)

1. A method for preparing a hydrodenitrogenation catalyst, comprising:

(1) sequentially dipping the physical pore-enlarging agent by using an aluminum salt solution and a solution containing a first active metal component, drying and roasting to obtain a modified physical pore-enlarging agent;

(2) kneading the modified physical pore-expanding agent obtained in the step (1) and pseudo-boehmite, molding, drying and roasting to obtain an intermediate;

(3) immersing the intermediate obtained in the step (2) into an ammonium bicarbonate solution, then carrying out sealing heat treatment, drying and roasting to obtain a modified alumina-based carrier;

(4) and (3) dipping the modified alumina-based carrier obtained in the step (3) in a solution containing a second active metal component, drying and roasting to obtain the hydrodenitrogenation catalyst.

2. The method of claim 1, wherein: the aluminum salt solution in the step (1) is one or a mixture of more of aluminum chloride solution, aluminum sulfate solution, aluminum nitrate solution and aluminum isopropoxide solution, preferably aluminum nitrate solution, the mass concentration of the aluminum salt solution is 5% -10% calculated by alumina, the dosage of the aluminum salt solution is used for completely immersing the physical pore-expanding agent, and the immersion time is 1-4 hours.

3. The method of claim 1, wherein: the solution containing the first active metal component in the step (1) is a solution containing a VIB group metal component and/or a VIII group metal component, wherein the VIB group metal is selected from W, Mo, the VIII group metal is selected from Co and Ni, the concentration of the VIB group metal is 2-5g/100mL calculated by metal oxides, the concentration of the VIII group metal is 0.5-1g/100mL calculated by metal oxides, the dosage of the solution containing the first active metal component is used for completely immersing the physical pore-expanding agent, and the immersion time is 1-4 hours.

4. The method of claim 1, wherein: the physical pore-enlarging agent in the step (1) is one or more of activated carbon and wood chips, and the particle size of the physical pore-enlarging agent is 3-7 mu m.

5. The method of claim 1, wherein: the drying in the step (1) is drying at the temperature of 100-140 ℃ for 1-4 hours, the roasting is roasting at the temperature of 400-500 ℃ for 3-6 hours, the roasting is carried out under the protection condition of inert atmosphere, and the inert atmosphere is preferably nitrogen.

6. The method of claim 1, wherein: the addition amount of the modified physical pore-expanding agent in the step (2) is 8-15 wt% of the weight of the obtained intermediate.

7. The method of claim 1, wherein: the drying in the step (2) is drying at the temperature of 100-140 ℃ for 1-4 hours, the roasting is roasting at the temperature of 600-750 ℃ for 3-6 hours, and the roasting is carried out in the air atmosphere.

8. The method of claim 1, wherein: the mass ratio of the using amount of the ammonium bicarbonate solution in the step (3) to the added intermediate is 4:1-7:1, and the mass concentration of the ammonium bicarbonate solution is 15-25%.

9. The method of claim 1, wherein: the sealing heat treatment temperature in the step (3) is 120-160 ℃, the constant temperature treatment time is 4-8 hours, and the heating rate is 5-20 ℃/min.

10. A method according to claim 1 or 9, characterized by: and (3) sealing pretreatment is carried out before sealing heat treatment, the pretreatment temperature is 60-100 ℃, the constant temperature treatment time is 2-4 hours, the temperature rise rate before pretreatment is 10-20 ℃/min, the temperature rise rate after pretreatment is 5-10 ℃/min, and the temperature rise rate after pretreatment is at least 3 ℃/min lower than that before pretreatment, preferably at least 5 ℃/min lower.

11. The method of claim 1, wherein: the solution containing the second hydrogenation active component in the step (4) is a solution containing group VIB and/or group VIII metal components, wherein the group VIB metal is selected from one or more of W, Mo, the group VIII metal is selected from one or more of Co and Ni, the concentration of the group VIB metal is 8-20g/100mL calculated by metal oxides, the concentration of the group VIII metal is 2.5-8.0g/100mL calculated by metal oxides, and equal-volume impregnation or supersaturated impregnation is adopted during impregnation.

12. The method of claim 1, wherein: the drying temperature in the step (4) is 80-160 ℃, the drying time is 6-10 hours, and the roasting is carried out for 4-8 hours at the temperature of 450-550 ℃.

13. A method according to claim 1 or 3 or 11, characterized by: the weight ratio of the first hydrogenation active component to the second hydrogenation active component in terms of oxide is 1:80-1: 40.

14. A hydrodenitrogenation catalyst, characterized in that the catalyst is prepared by a process according to any one of claims 1-13.

15. The catalyst of claim 14, wherein: the catalyst comprises a modified alumina-based carrier and a second active metal component, wherein the modified alumina-based carrier is a modified alumina-based carrier containing a first active metal component, the modified alumina-based carrier comprises main modified alumina and rodlike modified alumina, the main modified alumina is modified alumina with micron-sized pore channels, and at least part of rodlike modified alumina is distributed on the outer surface of the main modified alumina and in the micron-sized pore channels with the pore diameter D of 3-7 mu m.

16. The catalyst of claim 14, wherein: based on the weight of the catalyst, the total content of the first hydrogenation active component and the second hydrogenation active component is 10.0-30.0%, preferably the content of the VIB group metal is 8.0-20.0% calculated by oxide, and the content of the VIII group metal is 2.0-10.0% calculated by oxide.

17. The catalyst of claim 14, wherein: the rodlike modified alumina is basically distributed on the outer surface of the main body modified alumina and in the micron-sized pore channels.

18. The catalyst of claim 14, wherein: in the modified alumina-based carrier, the length of the rod-shaped modified alumina in the micron-sized pore channel is mainly 0.3D-0.9D; the length of the outer surface rod-shaped modified alumina is mainly 3-8 μm.

19. The catalyst of claim 14, wherein: the diameter of the rod-shaped modified alumina is 80-260 nm.

20. The catalyst of claim 14, wherein: in the modified alumina-based carrier, at least one end of at least part of rod-shaped modified alumina is attached to the micron-sized pore channel wall of the main modified alumina, preferably at least one end of at least part of rod-shaped modified alumina is combined with the micron-sized pore channel wall to form a whole with the main modified alumina, and further preferably at least one end of the rod-shaped modified alumina in the micron-sized pore channel is combined with the micron-sized pore channel wall to form a whole with the main modified alumina.

21. The catalyst of claim 14, wherein: in the modified alumina-based carrier, one end of at least part of rod-shaped modified alumina is attached to the outer surface of the main modified alumina, preferably, one end of at least part of rod-shaped modified alumina is combined with the outer surface of the main modified alumina, and the other end of at least part of rod-shaped modified alumina extends outwards and is integrated with the main modified alumina.

22. The catalyst of claim 14, wherein: in the modified alumina-based carrier, the coverage rate of the rod-shaped modified alumina in the micron-sized pore canal of the main body modified alumina accounts for 75-95%, and the coverage rate of the rod-shaped modified alumina on the outer surface of the main body modified alumina accounts for 70-95%.

23. The catalyst of claim 14, wherein: the specific surface area of the catalyst is 200-330m²(iv)/g, pore volume of 0.8-1.75mL/g, crush strength of 15-22N/mm.

24. The catalyst of claim 14, wherein: the pores formed by the rod-shaped modified alumina staggered with each other in a random order are concentrated between 100-600 nm.

25. The catalyst of claim 14, wherein: the pore distribution of the catalyst is as follows: the pore volume occupied by the pores with the pore diameter of less than 10nm is less than 20 percent of the total pore volume, the pore volume occupied by the pores with the pore diameter of 10-30nm is 40-60 percent of the total pore volume, the pore volume occupied by the pores with the pore diameter of 100-600nm is 15-25 percent of the total pore volume, and the pore volume occupied by the pores with the pore diameter of more than 1000nm is less than 5 percent of the total pore volume.

Technical Field

The invention relates to the field of catalyst preparation, in particular to a preparation method of a residual oil hydrodenitrogenation catalyst.

Background

The existing residual oil hydrotreating technology mainly aims at providing raw materials for a catalytic cracking process, has low requirements on nitrogen content of a residual oil hydrotreating product, the nitrogen content can reach more than 1000 mug/g, and the requirements on metal content are not high, but the operation period of a residual oil hydrotreating device is only 1 year generally. If the residual oil hydrotreating product is required to meet the requirements of hydrocracking raw materials, the nitrogen and metal contents in the residual oil hydrotreating product are greatly reduced, but the requirements are difficult to meet in the view of the current process and catalyst, and even if the requirements can be met, the residual oil hydrotreating product has no application value because the running period is too short.

The light oil yield of the existing residual oil hydrotreating technology is low, and is generally about 15 percent. If the yield of light oil is improved, acidity must be increased to improve the cracking function, but the pore volume of the catalytic material in the prior art is small, generally 0.5-0.6mL/g, the metal and carbon capacity is too low to keep the high-acidity catalyst in normal operation, and the catalyst is quickly deactivated.

The through channels are very important for petroleum catalysts, and particularly, large through channels are needed for metal deposition of residual oil macromolecules, so that the catalyst achieves the maximum metal capacity, and the service life of the catalyst is prolonged. The molecular weight of the asphaltene is about 2000, and the formed micelle is 10-00 nm. Since nitrogen coexists with metals in the asphaltene micelle, a demetallization reaction will be accompanied at the same time as the denitrification. The residual oil hydrodenitrogenation catalyst is a necessary condition for long-term operation from the beginning of operation to the failure, and sufficient 10-100nm through-channels are maintained from the surface to the center to allow residual oil macromolecules to diffuse and metal to deposit.

CN1042138C discloses a preparation method of a hydrofining catalyst. The method prepares the catalyst with higher active metal content by a one-time dipping method, the catalyst has certain hydrodenitrogenation performance, but the pore channel is too small to facilitate the diffusion of macromolecules, and the carbon residue removal performance needs to be improved. CN1257103A discloses a preparation method of a hydrotreating catalyst, which adopts a one-time kneading method to obtain a residual oil hydrodenitrogenation catalyst with high denitrification capability, but has a pore passage too small to prepare a bifunctional catalyst with denitrification performance and high residual carbon removal activity.

Disclosure of Invention

Aiming at the defects of single function and poor residual carbon removal capability of a residual oil hydrodenitrogenation catalyst in the prior art, the invention provides a preparation method of the residual oil hydrodenitrogenation catalyst, the catalyst prepared by the method has higher hydrodenitrogenation capability and hydrodecarbonization capability, and the catalyst is suitable for the field of residual oil hydrogenation.

The invention provides a preparation method of a hydrodenitrogenation catalyst, which comprises the following steps:

(1) sequentially dipping the physical pore-enlarging agent by using an aluminum salt solution and a solution containing a first active metal component, drying and roasting to obtain a modified physical pore-enlarging agent;

(2) kneading the modified physical pore-expanding agent obtained in the step (1) and pseudo-boehmite, molding, drying and roasting to obtain an intermediate;

(3) immersing the intermediate obtained in the step (2) into an ammonium bicarbonate solution, then carrying out sealing heat treatment, drying and roasting to obtain a modified alumina-based carrier;

(4) and (3) dipping the modified alumina-based carrier obtained in the step (3) in a solution containing a second active metal component, drying and roasting to obtain the hydrodenitrogenation catalyst.

In the method, the aluminum salt solution in the step (1) can be one or a mixture of more of an aluminum chloride solution, an aluminum sulfate solution, an aluminum nitrate solution and an aluminum isopropoxide solution, preferably an aluminum nitrate solution, the mass concentration of the aluminum salt solution is 5% -10% calculated by alumina, the amount of the aluminum salt solution is used for completely immersing the physical pore-expanding agent, and the immersion time is 1-4 hours.

In the method, the solution containing the first active metal component in the step (1) is a solution containing a VIB group and/or VIII group metal component, wherein the VIB group metal is selected from W, Mo, the VIII group metal is selected from Co and Ni, the concentration of the VIB group metal is 2-5g/100mL calculated by metal oxides, the concentration of the VIII group metal is 0.5-1g/100mL calculated by metal oxides, the dosage of the solution containing the first active metal component is used for completely immersing the physical pore-expanding agent, and the immersion time is 1-4 hours.

In the method, the physical pore-enlarging agent in the step (1) can be one or more of activated carbon and wood chips, and the particle size of the physical pore-enlarging agent is about 3-7 mu m.

In the method, after the aluminum salt solution is used for soaking the physical pore-expanding agent in the step (1), the physical pore-expanding agent is dried firstly, and then the solution containing the first active metal component is used for soaking the physical pore-expanding agent, wherein the drying is 100-140 ℃ for 1-4 hours.

In the method of the invention, the drying in the step (1) is drying at 140 ℃ for 1-4 hours at 100-.

In the method of the present invention, the pseudoboehmite prepared in the step (2) can be a pseudoboehmite prepared by any method, for example, the pseudoboehmite is prepared by a precipitation method, an aluminum alkoxide hydrolysis method, an inorganic salt sol-gel method, a hydrothermal method, a vapor deposition method, and the like, and the addition amount of the modified physical pore-enlarging agent is 8wt% to 15wt% of the weight of the intermediate.

In the method, the kneading molding in the step (2) is carried out by adopting a conventional method in the field, and a proper amount of conventional molding aids, such as one or more of peptizing agents, extrusion aids and the like, can be added according to needs in the molding process. The peptizing agent is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, oxalic acid and the like. The extrusion aid is sesbania powder.

In the method, the drying in the step (2) is drying at 100-140 ℃ for 1-4 hours, the roasting is roasting at 600-750 ℃ for 3-6 hours, and the roasting is carried out in an air atmosphere. The intermediate may be in the form of a conventional alumina support, such as a sphere, having a particle size of typically 0.5-8.0mm, such as a bar, clover, etc., having a diameter of about 0.2-3.0mm and a length of about 0.5-8.0 mm.

In the method, the mass ratio of the using amount of the ammonium bicarbonate solution in the step (3) to the added intermediate is 4:1-7:1, and the mass concentration of the ammonium bicarbonate solution is 15-25%.

In the method of the invention, the sealing heat treatment temperature in the step (3) is 120-.

In the method, the step (3) is preferably carried out before the sealing heat treatment, the sealing pretreatment is carried out, the pretreatment temperature is 60-100 ℃, the constant temperature treatment time is 2-4 hours, the temperature rise rate before the pretreatment is 10-20 ℃/min, the temperature rise rate after the pretreatment is 5-10 ℃/min, and the temperature rise rate after the pretreatment is at least 3 ℃/min lower than that before the pretreatment, preferably at least 5 ℃/min lower than that before the pretreatment.

In the method of the invention, the drying conditions in the step (3) are that the drying temperature is 100-160 ℃, the drying time is 4-8 hours, the roasting temperature is 550-650 ℃, and the roasting time is 4-6 hours.

In the method, the solution containing the second hydrogenation active component in the step (4) is a solution containing group VIB and/or group VIII metal components, wherein the group VIB metal is selected from W, Mo, the group VIII metal is selected from Co and Ni, the concentration of the group VIB metal is 8-20g/100mL calculated by metal oxides, the concentration of the group VIII metal is 2.5-8.0g/100mL calculated by metal oxides, and equal-volume impregnation or supersaturated impregnation can be adopted during impregnation. The drying temperature is 80-160 ℃, the drying time is 6-10 hours, and the roasting is 4-8 hours at the temperature of 450-550 ℃.

In the method of the present invention, the first hydrogenation active component and the second hydrogenation active component may be the same or different. The weight ratio of the first hydrogenation active component to the second hydrogenation active component in terms of oxide is 1:80-1: 40.

In another aspect, the present invention provides a hydrodenitrogenation catalyst, which is prepared by the above method.

The hydrodenitrogenation catalyst comprises a modified alumina-based carrier and a second active metal component, wherein the modified alumina-based carrier is a modified alumina-based carrier containing a first active metal component, the modified alumina-based carrier comprises main modified alumina and rodlike modified alumina, the main modified alumina is modified alumina with micron-sized pore channels, and at least part of rodlike modified alumina is distributed on the outer surface of the main modified alumina and in the micron-sized pore channels with the pore diameter D of 3-7 mu m.

The micron-sized pore channels in the invention refer to micron-sized pore channels with the pore diameter of 3-7 μm.

The first hydrogenation active component is VIB group and/or VIII group metal, the second hydrogenation active component is VIB group and/or VIII group metal, and the first hydrogenation active component and the second hydrogenation active component can be the same or different. Based on the weight of the hydrodenitrogenation catalyst, the total content of the first hydrogenation active component and the second hydrogenation active component is 10.0-30.0%, preferably, the content of the VIB group metal is 8.0-20.0% calculated by oxides, and the content of the VIII group metal is 2.0-10.0% calculated by oxides.

In the modified alumina-based carrier, the rodlike modified alumina is basically distributed on the outer surface of the main modified alumina and in the micron-sized pore channel. The rod-shaped modified alumina distributed on the outer surface of the main body modified alumina and in the micron-sized pore channels accounts for more than 95 percent of the total weight of all the rod-shaped modified aluminas, and preferably more than 97 percent.

In the modified alumina-based carrier, the length of the rod-shaped modified alumina in the micron-sized pore channel is mainly 0.3D-0.9D (which is 0.3-0.9 time of the diameter of the micron-sized pore channel), namely the length of more than 85 percent of the rod-shaped modified alumina in the micropore is 0.3D-0.9D by weight; the length of the rod-shaped modified alumina on the outer surface is mainly 3-8 μm, namely, the length of more than 85 percent of the rod-shaped modified alumina on the outer surface is 3-8 μm.

The diameter of the rod-shaped modified alumina is 80-260 nm.

In the modified alumina-based carrier, rod-shaped modified alumina is distributed in a disordered and mutually staggered state in micron-sized pore channels of main modified alumina.

In the modified alumina-based carrier, at least one end of at least part of rod-shaped modified alumina is attached to the micron-sized pore channel wall of the main body modified alumina, and preferably, at least one end of at least part of rod-shaped modified alumina is bonded to the micron-sized pore channel wall and is integrated with the main body modified alumina. Further preferably, at least one end of the rod-like modified alumina in the micron-sized pore channel is bonded to the wall of the micron-sized pore channel, and is integrated with the main body of the modified alumina.

In the modified alumina-based carrier, rod-like modified aluminas are distributed in a disordered and mutually staggered state on the outer surface of a main body of modified alumina.

In the modified alumina-based carrier, one end of at least part of rod-shaped modified alumina is attached to the outer surface of the main modified alumina, and preferably, one end of at least part of rod-shaped modified alumina is combined with the outer surface of the main modified alumina, and the other end of the rod-shaped modified alumina extends outwards and is integrated with the main modified alumina. Further preferably, one end of the rod-shaped modified alumina on the outer surface of the body modified alumina is bonded to the outer surface of the body modified alumina, and the other end thereof protrudes outward and is integrated with the body.

In the modified alumina-based carrier, the coverage rate of the rod-shaped modified alumina in the micron-sized pore canal of the main body modified alumina is 75-95%, wherein the coverage rate refers to the percentage of the surface of the inner surface of the micron-sized pore canal of the main body modified alumina, which is occupied by the rod-shaped modified alumina, in the inner surface of the micron-sized pore canal of the main body modified alumina. The coverage rate of the rod-shaped modified alumina on the outer surface of the main body modified alumina is 70-95%, wherein the coverage rate refers to the percentage of the surface occupied by the rod-shaped modified alumina on the outer surface of the main body modified alumina.

The hydrodenitrogenation catalyst of the invention has the following properties: the specific surface area is 200-330m²The pore volume is 0.8-1.75mL/g, and the crushing strength is 15-22N/mm.

In the hydrodenitrogenation catalyst, the pores formed by the disordered mutual interlacing of the rod-shaped modified alumina are concentrated between 100nm and 600 nm.

The hole distribution of the hydrodenitrogenation catalyst is as follows: the pore volume occupied by the pores with the pore diameter of less than 10nm is less than 20 percent of the total pore volume, the pore volume occupied by the pores with the pore diameter of 10-30nm is 40-60 percent of the total pore volume, the pore volume occupied by the pores with the pore diameter of 100-600nm is 15-25 percent of the total pore volume, and the pore volume occupied by the pores with the pore diameter of more than 1000nm is less than 5 percent of the total pore volume.

The hydrodenitrogenation catalyst is suitable for a residual oil hydrodenitrogenation treatment process, and has high denitrification rate and high hydrodenitrogenation residual rate.

Compared with the prior art, the invention has the following advantages:

1. in the process of preparing the hydrodenitrogenation catalyst, the physical pore-enlarging agent firstly adsorbs an aluminum salt solution, then adsorbs an active metal solution, and forms an active metal-alumina composite oxide to be attached to the physical pore-enlarging agent during roasting in an inert atmosphere. When the carrier is roasted after being formed, the active metal-aluminum oxide composite oxide in the physical pore-expanding agent is anchored in the micron-sized pore channel, when the carrier is subjected to sealed hydrothermal treatment in an ammonium bicarbonate solution system, rod-shaped alumina and rod-shaped active metal-aluminum oxide composite oxide are formed in the micron-sized pore channel, and the rod-shaped results are mutually staggered to form a through pore channel structure. In addition, during hydrothermal treatment, active metal components in the micron-sized pore channels are redispersed, and the action of active metals and carriers is improved, so that the hydrodenitrogenation activity and the carbon residue removal activity of the catalyst are improved.

2. In the process of preparing the hydrodenitrogenation catalyst, the hydrodenitrogenation catalyst is pretreated at a certain temperature before sealing heat treatment, the pretreatment condition is relatively mild, and NH is slowly formed on the outer surface of an intermediate in a sealed and hydrothermal mixed atmosphere of carbon dioxide and ammonia gas₄Al(OH)₂CO₃Crystal nuclei, raising the reaction temperature NH during the post-heat treatment₄Al(OH)₂CO₃The crystal nucleus continues to grow evenly to make rod-shaped NH₄Al(OH)₂CO₃Having uniform diameter and length while increasing rod-like NH₄Al(OH)₂CO₃Coverage on the outer surface of the intermediate body and the inner surface of the micron-sized pore channel.

3. The hydrodenitrogenation catalyst disclosed by the invention fully utilizes micron-sized pore channels of the intermediate, and the rod-shaped alumina is irregularly and mutually staggered in the micron-sized pore channels, so that on one hand, the penetrability of the micron-sized pore channels is maintained, the specific surface area of the catalyst is improved, the mechanical strength is enhanced, on the other hand, gas generated by combustion of a physical pore-expanding agent plays a certain pore-expanding role on the intermediate nanoscale pore channels, the penetrability and the uniformity of the nanoscale pore channels are further promoted, and the diffusion performance of a macromolecular reactant is improved.

Drawings

FIG. 1 is an SEM photograph of a modified alumina-based support obtained in example 1;

wherein the reference numbers are as follows: 1-main body modified alumina, 2-rod-shaped modified alumina and 3-micron pore canal.

Detailed Description

The following examples are provided to further illustrate the technical solutions of the present invention, but the present invention is not limited to the following examples. In the present invention, wt% is a mass fraction and v% is a volume fraction.

Application N₂Physical adsorption-desorption characterization of the pore structures of the catalysts in the examples and the comparative examples, the specific operations are as follows: adopting ASAP-2420 type N₂And the physical adsorption-desorption instrument is used for characterizing the pore structure of the sample. A small amount of samples are taken to be treated for 3 to 4 hours in vacuum at the temperature of 300 ℃, and finally, the product is placed under the condition of liquid nitrogen low temperature (-200 ℃) to be subjected to nitrogen absorption-desorption test. Wherein the specific surface area is obtained according to a BET equation, and the distribution rate of the pore volume and the pore diameter below 50nm is obtained according to a BJH model.

Mercury pressing method: the mercury porosimeter is used for representing the pore diameter distribution of the catalysts in the examples and the comparative examples, and the specific operation is as follows: and characterizing the distribution of sample holes by using an American microphone AutoPore9500 full-automatic mercury porosimeter. The samples were dried, weighed into an dilatometer, degassed for 30 minutes while maintaining the vacuum conditions given by the instrument, and filled with mercury. The dilatometer was then placed in the autoclave and vented. And then carrying out a voltage boosting and reducing test. The mercury contact angle is 130 degrees, and the mercury interfacial tension is 0.485N.cm^-1The distribution ratio of pore diameter of 100nm or more is measured by mercury intrusion method.

The microstructure of the catalyst and the modified alumina-based carrier is represented by a scanning electron microscope, and the method specifically comprises the following operation: a JSM-7500F scanning electron microscope is adopted to represent the microstructure of the catalyst and the modified alumina-based carrier, the accelerating voltage is 5KV, the accelerating current is 20 muA, and the working distance is 8 mm.