阅读说明：本技术 一种渣油加氢脱氮催化剂及其制备方法 (Residual oil hydrodenitrogenation catalyst and preparation method thereof ) 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：本发明公开了一种渣油加氢脱氮催化剂及其制备方法。该催化剂包括改性氧化铝基载体、钼和镍金属组分,所述改性氧化铝基载体含有钨和钴金属组分,所述改性氧化铝基载体包括主体改性氧化铝和棒状改性氧化铝,所述的主体改性氧化铝为具有微米级孔道的改性氧化铝,其中至少部分棒状改性氧化铝分布在主体改性氧化铝的外表面和孔直径D为3-7μm的微米级孔道中。该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 residual oil hydrodenitrogenation catalyst and a preparation method thereof. The catalyst comprises a modified alumina-based carrier, molybdenum and nickel metal components, wherein the modified alumina-based carrier contains tungsten and cobalt metal components, 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 catalyst has high hydrodenitrogenation capacity and hydrodecarbonization capacity, and is suitable for the field of residual oil hydrogenation.)

1. A residual oil hydrodenitrogenation catalyst is characterized in that: the catalyst comprises a modified alumina-based carrier, molybdenum and nickel metal components, wherein the modified alumina-based carrier contains tungsten and cobalt metal components, 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.

2. The catalyst of claim 1, wherein: the total content of the tungsten and the cobalt is 2 to 10 percent, preferably 2 to 8 percent calculated by oxide, based on the weight of the residual oil hydrodenitrogenation catalyst; the total content of the molybdenum and the nickel is 10 to 20 percent, and preferably 15 to 25 percent calculated by oxide.

3. A catalyst according to claim 1 or 2, wherein: the weight ratio of tungsten to cobalt is 1:1-3:1, and the weight ratio of molybdenum to nickel is 2:1-5: 1.

4. The catalyst of claim 1, 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.

5. The catalyst of claim 1, wherein: the length of the rod-shaped modified alumina in the micron-sized pore channel is mainly 0.3D-0.9D, and the length of the rod-shaped modified alumina on the outer surface is mainly 3-8 μm.

6. The catalyst of claim 1, wherein: the diameter of the rod-shaped modified alumina is 80-260 nm.

7. The catalyst of claim 1, 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 body modified alumina, and 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 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.

8. The catalyst of claim 1, 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, 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.

9. The catalyst of claim 1, wherein: the coverage rate of the rod-shaped modified alumina in the micron-sized pore channel of the main body modified alumina is 70-95%, and the coverage rate of the rod-shaped modified alumina on the outer surface of the main body modified alumina is 70-95%.

10. The catalyst of claim 1, wherein: the properties of the catalyst are as follows: the specific surface area is 190-300m²(iv)/g, pore volume of 0.75-1.2mL/g, crush strength of 10-20N/mm.

11. The catalyst of claim 1, wherein: the pores formed by the rod-shaped modified alumina staggered with each other in a random order are concentrated between 100-600 nm.

12. The catalyst of claim 1, 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 10-20 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.

13. A process for preparing a resid hydrodenitrogenation catalyst as recited in any one of claims 1 to 12, comprising:

(1) kneading and molding a physical pore-expanding agent, a pseudo-boehmite, a tungsten and cobalt metal component source, drying and roasting to obtain an intermediate;

(2) immersing the intermediate obtained in the step (1) into an ammonium bicarbonate solution, then carrying out sealing heat treatment, drying and roasting the heat-treated material to obtain a modified alumina-based carrier;

(3) and (3) dipping the modified alumina-based carrier obtained in the step (2) in a solution containing molybdenum and nickel metal components, drying and roasting to obtain the residual oil hydrodenitrogenation catalyst.

14. The method of claim 13, wherein: the physical pore-enlarging agent in the step (1) is one or more of activated carbon and sawdust, the particle size of the physical pore-enlarging agent is 3-7 mu m, and the addition amount of the physical pore-enlarging agent is 8-15 wt% of the weight of the intermediate.

15. The method of claim 13, wherein: the tungsten and cobalt metal component source in the step (1) is a metal salt containing tungsten and cobalt, the metal salt containing tungsten is one or more of ammonium tungstate and ammonium metatungstate, and the metal salt containing cobalt is one or more of cobalt nitrate and basic cobalt carbonate.

16. The method of claim 13, wherein: the drying conditions in the step (1) are as follows: the drying temperature is 80-160 ℃, and the drying time is 6-10 hours; the roasting temperature is 650-750 ℃, and the roasting time is 4-6 hours.

17. The method of claim 13, wherein: the mass ratio of the using amount of the ammonium bicarbonate solution in the step (2) to the intermediate added in the step (2) is 4:1-7:1, and the mass concentration of the ammonium bicarbonate solution is 15% -25%.

18. The method of claim 13, wherein: the sealing heat treatment temperature in the step (2) is 120-160 ℃, the constant temperature treatment time is 4-8 hours, and the heating rate is 5-20 ℃/min.

19. A method according to claim 13 or 18, characterized by: and (2) performing sealing pretreatment before sealing heat treatment, wherein 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.

20. The method of claim 13, wherein: the drying temperature in the step (2) is 80-160 ℃, and the drying time is 6-10 hours; the roasting temperature in the step (2) is 550-750 ℃, and the roasting time is 4-6 hours.

21. The method of claim 13, wherein: the source solution of the metal components containing molybdenum and nickel in the step (3) is an acid solution, an aqueous solution or an ammonia solution containing molybdenum and nickel; the content of molybdenum in the solution containing the molybdenum and nickel metal components is 6.5-17.5g/100mL calculated by metal oxide, and the content of nickel is 1.5-5.0g/100mL calculated by metal oxide.

22. The method of claim 13, wherein: the drying temperature in the step (3) is 80-160 ℃, and the drying time is 6-10 hours; the roasting temperature in the step (3) is 450-550 ℃, and the roasting time is 4-6 hours.

Technical Field

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

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 can be greatly reduced, and the requirements are difficult to achieve from the aspects of the current process and catalyst, or the operation period is too short to have application value.

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 10-100 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 method for preparing a hydrorefining catalyst, which is a method for preparing a catalyst with higher active metal content by a one-step impregnation method, wherein 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 the defect that a pore passage is too small to obtain 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 residual oil hydrodenitrogenation catalyst and a preparation method thereof.

The invention provides a residual oil hydrodenitrogenation catalyst, which comprises a modified alumina-based carrier, molybdenum and nickel metal components, wherein the modified alumina-based carrier contains tungsten and cobalt metal components, the modified alumina-based carrier comprises main modified alumina and rod-shaped modified alumina, the main modified alumina is modified alumina with micron-sized pore channels, and at least part of the rod-shaped modified alumina is distributed on the outer surface of the main modified alumina and 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 residual oil hydrodenitrogenation catalyst provided by the invention has the advantages that the total content of tungsten and cobalt calculated by oxides is 2% -10%, and preferably 2% -8% on the basis of the weight of the residual oil hydrodenitrogenation catalyst; the total content of the molybdenum and the nickel is 10 to 20 percent, and preferably 15 to 25 percent calculated by oxide.

Further, the weight ratio of tungsten to cobalt is 1:1-3:1, and the weight ratio of molybdenum to nickel is 2:1-5: 1.

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 channels. 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 of the present invention, at least one end of at least a part of the rod-shaped modified alumina is attached to the micron-sized pore wall of the main body modified alumina, and preferably, at least one end of at least a part of the rod-shaped modified alumina is bonded to the micron-sized pore wall to be 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 of the present invention, rod-like modified aluminas are distributed in a disordered and mutually staggered state on the outer surface of the main body modified alumina.

In the modified alumina-based carrier of the present invention, one end of at least a part of the rod-shaped modified alumina is attached to the outer surface of the main modified alumina, and preferably, one end of at least a part of the rod-shaped modified alumina is bonded to the outer surface of the main modified alumina, and the other end thereof protrudes outward 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 70-95%, 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 residual oil hydrodenitrogenation catalyst has the following properties: the specific surface area is 190-300m²(iv) g, pore volume of 0.75-1.2mL/g, crush strength of 10-20N/mm.

In the residual oil hydrodenitrogenation catalyst, the pores formed by the disordered and staggered rod-shaped modified alumina are concentrated between 100nm and 600 nm.

The residual oil hydrodenitrogenation catalyst of the present invention has the following pore distribution: 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 10-20 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 residual oil hydrodenitrogenation catalyst of the present invention may further contain an auxiliary agent, such as one or more of phosphorus, boron, silicon, and the like. The weight content of the auxiliary agent in the catalyst is less than 10.0 percent, preferably 0.1 to 10.0 percent in terms of oxide.

The second aspect of the present invention provides a preparation method of a residual oil hydrodenitrogenation catalyst, including:

(1) kneading and molding a physical pore-expanding agent, a pseudo-boehmite, a tungsten and cobalt metal component source, drying and roasting to obtain an intermediate;

(2) immersing the intermediate obtained in the step (1) into an ammonium bicarbonate solution, then carrying out sealing heat treatment, drying and roasting the heat-treated material to obtain a modified alumina-based carrier;

(3) and (3) dipping the modified alumina-based carrier obtained in the step (2) in a solution containing molybdenum and nickel metal components, drying and roasting to obtain the residual oil hydrodenitrogenation catalyst.

In the method, the physical pore-expanding agent in the step (1) can be one or more of activated carbon and wood chips, the particle size of the physical pore-expanding agent is about 3-7 mu m, and the addition amount of the physical pore-expanding agent is 8-15 wt% of the weight of the intermediate.

In the method, the tungsten and cobalt metal component source in the step (1) is a metal salt containing tungsten and cobalt, the metal salt containing tungsten is preferably one or more of ammonium tungstate and ammonium metatungstate, and the metal salt containing cobalt is preferably one or more of cobalt nitrate and basic cobalt carbonate.

In the method of the present invention, the pseudoboehmite described in the step (1) may be a pseudoboehmite prepared by any method, for example, 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.

In the method, the kneading molding in the step (1) 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.

The drying conditions in the step (1) are as follows: the drying temperature is 80-160 ℃, and the drying time is 6-10 hours. The roasting temperature is 650-750 ℃, and the roasting time is 4-6 hours; the calcination is carried out in an oxygen-containing atmosphere, preferably 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 (2) to the intermediate added in the step (2) 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 (2) is 120-.

In the method, the step (2) 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.

In the method, the drying temperature in the step (2) is 80-160 ℃, and the drying time is 6-10 hours; the roasting temperature in the step (2) is 550-750 ℃, and the roasting time is 4-6 hours.

In the method, the metal component source solution containing molybdenum and nickel in the step (3) is an acid solution, an aqueous solution or an ammonia solution containing molybdenum and nickel. The content of molybdenum in the solution containing the molybdenum and nickel metal components is 6.5-17.5g/100mL calculated by metal oxide, and the content of nickel is 1.5-5.0g/100mL calculated by metal oxide.

In the method of the present invention, the impregnation in the step (3) may be carried out by a conventional impregnation method, and may be carried out by an unsaturated impregnation method, a saturated impregnation method, or the like, preferably a saturated impregnation method

In the method, the drying temperature in the step (3) is 80-160 ℃, and the drying time is 6-10 hours; the roasting temperature in the step (3) is 450-550 ℃, and the roasting time is 4-6 hours.

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. the residual oil hydrodenitrogenation catalyst of the invention makes full use of micron-scale pore channels of the main body modified alumina, and the rod-shaped aluminas are distributed in the micron-scale pore channels in a disordered and staggered manner, so that on one hand, the penetrability of the micron-scale pore channels is maintained, the specific surface area of the carrier is improved, the mechanical strength is enhanced, on the other hand, gas generated during roasting of the physical pore-expanding agent plays a certain role in expanding the nanometer-scale pore channels, the penetrability and the uniformity of the nanometer-scale pore channels are further promoted, and the diffusion capacity of reactant molecules is improved. Therefore, the hydrodenitrogenation catalyst provided by the invention overcomes the problem that the large aperture, the specific surface area and the mechanical strength are not compatible due to the adoption of a physical pore-expanding agent.

2. One end of the surface rodlike alumina of the residual oil hydrodenitrogenation catalyst is combined on the outer surface of the main alumina, and the other end of the surface rodlike alumina extends outwards.

3. In the preparation method, tungsten and cobalt metal components are mixed in advance when the intermediate is formed, the effect of the active component and the alumina carrier is effectively regulated and controlled when the intermediate is subjected to sealing heat treatment in an ammonium bicarbonate aqueous solution, on the other hand, the metal components added twice are different and are introduced into the catalyst in different modes, and further, by limiting the specific weight ratio among the metal components, the active components play a synergistic and complementary role, and the hydrodenitrogenation activity and the hydrodecarbonization activity of the catalyst are improved.

4. In the process of preparing the hydrodenitrogenation catalyst, the hydrodenitrogenation catalyst is preferably 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 alumina intermediate and the inner surface of the micron-sized pore channel. NH (NH)₄Al(OH)₂CO₃The gases such as ammonia gas and carbon dioxide generated during thermal decomposition play a good role in expanding the pore of the intermediate again, so that the penetration and uniformity of the pore are further promoted, and the diffusion capacity of reactant molecules is improved.

5. The hydrodenitrogenation catalyst has the characteristics of large aperture, large pore volume and strong pore passage connectivity, is favorable for mass transfer and diffusion of residual oil reactant molecules, and has high hydrodenitrogenation and residual carbon removal activities.

Drawings

FIG. 1 is an SEM image of a modified alumina-based support prepared 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.