A hydrodenitrogenation catalyst, its preparation method and application

Abstract

This invention discloses a hydrodenitrification catalyst, its preparation method, and its application, comprising the following steps: (1) AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2 μm and alumina are sequentially added to deionized water, and a carrier raw material slurry is obtained by ultrasonic emulsification. The carrier raw material slurry is filtered, dried, and ground to obtain a carrier raw material powder. The carrier raw material powder is mixed evenly with a molding aid, and then extruded, dried, and calcined to obtain a catalyst support; (2) Metal salts containing zinc, nickel, and tungsten elements are dissolved in deionized water to obtain a metal impregnation solution. The catalyst support is impregnated using an equal-volume impregnation method, and then cured, dried, and calcined to obtain a hydrodenitrification catalyst. The preparation method of this invention can improve the utilization efficiency of AlPO4-5 phosphorus aluminum molecular sieve, inhibit the formation of nickel-aluminum spinel inert substances, promote the formation of a highly active hydrogenation phase by the active metal, improve the utilization efficiency of the active metal Ni, and thus improve the hydrogenation activity of the catalyst.

Description

Technical Field

[0001] This invention relates to a hydrodenitrification catalyst, its preparation method and application, and particularly to a deep hydrodenitrification catalyst for diesel fuel and its preparation method. Background Technology

[0002] Diesel hydrotreating processes include hydrorefining, hydromodification, hydrodepylation, and hydrocracking. Except for hydrorefining, the latter three processes require catalysts with strong acid-functional properties. Nitrogen compounds, especially basic nitrogen compounds, readily react strongly with acid-functional catalysts, poisoning their acidic centers and causing a rapid decline in their activity. This prevents the catalysts from performing their acid catalytic function properly, thus affecting the hydromodification, hydrodepylation, and hydrocracking processes. Therefore, deep removal of nitrogen compounds, especially basic nitrogen compounds, from diesel fuel is crucial to ensuring the full performance of catalysts used in these processes.

[0003] Nitrogen compounds in diesel fuel can be broadly classified into two categories: non-heterocyclic compounds (including aliphatic amines, aniline, and nitrile compounds) and heterocyclic compounds, which can be further divided into basic heterocyclic compounds (pyridine, quinoline, isoquinoline, acridine, etc.) and non-basic heterocyclic compounds (pyrrole, indole, and carbazole, etc.). Non-heterocyclic nitrogen compounds in diesel fuel are present in lower concentrations and are easier to remove, while heterocyclic nitrogen compounds, which are more difficult to remove, are present in higher concentrations.

[0004] The hydrogenation-denitrification (HDN) process of general heterocyclic nitrogen compounds mainly includes hydrogenation and CN-bond hydrogenolysis. Hydrogenation reactions are further divided into nitrogen heterocycle hydrogenation and aromatic ring hydrogenation. Because nitrogen heterocycles are less aromatic than aromatic rings, HDN of nitrogen-containing heterocycle components generally requires complete hydrogenation of the nitrogen-containing ring before the removal of the nitrogen atom. Similarly, aniline nitrogen-containing compounds also require aromatic ring hydrogenation saturation before CN-bond cleavage.

[0005] In summary, the hydrogenation saturation process of aromatic ring structures in heterocyclic nitrides is crucial for the denitrification of these nitrides. Since the hydrogenation saturation of aromatic ring structures is controlled by reaction thermodynamics and kinetics, under constant reaction pressure, increasing the reaction temperature leads to a trend of initially increasing and then decreasing the rate of aromatic ring hydrogenation.

[0006] To effectively remove nitrogen compounds from diesel fuel, many domestic and international diesel hydrotreating catalyst manufacturers have developed diesel hydrotreating catalysts with good denitrification activity, achieving effective removal of nitrogen compounds while performing ultra-deep desulfurization.

[0007] Chinese patent CN1778874A discloses a hydrodearomatization catalyst containing AlPO4-5 phosphorus aluminum molecular sieve. By utilizing the tunable acidity and concentrated pore distribution of AlPO4-5 phosphorus aluminum molecular sieve, the pore structure and surface acidity of the catalyst support are optimized, improving the dispersion of the metal active phase and promoting the formation of a highly active hydrogenation phase, thereby enhancing the catalyst's hydrogenation activity and increasing its hydrogenation saturation efficiency for aromatics in diesel fuel. However, the support and the active metals Ni and W easily interact to form inert substances such as nickel-aluminum spinel, reducing the utilization efficiency of the active metal Ni and consequently affecting and reducing the catalyst's hydrogenation activity.

[0008] Chinese patent CN102485332A discloses a distillate oil hydrodeacidification catalyst containing molecular sieves and its preparation method. The catalyst uses magnesium oxide, alumina, AlPO4-5 phosphorus aluminum molecular sieve, and ZSM-5 molecular sieve as support materials, and Ni or Co and W or Mo as active components to prepare a catalyst with high hydrodeacidification activity. This catalyst simultaneously exhibits hydrodesulfurization and hydrodenitrogenation activity. However, the preparation process of the catalyst support involves mechanically mixing the powdered materials and undergoing two drying and calcination processes, resulting in a lengthy and energy-intensive overall preparation process.

[0009] Diesel hydrorefining typically employs a fixed-bed hydrotreating reactor, using cloverleaf or cylindrical catalysts. The catalyst preparation process begins by mechanically mixing alumina powder, molecular sieve powder, and molding aids (tianqing powder, citric acid, and nitric acid aqueous solution) needed for the support. This mixture is then extruded into strip-shaped supports, dried, calcined, and impregnated with an active metal aqueous solution. Further drying and calcination yield the catalyst. However, the use of simple mechanical mixing methods in the catalyst support preparation process leads to insufficient and uneven mixing of the alumina and molecular sieve powders. Furthermore, the strong interactions between the catalyst metal components and the support during catalyst preparation make it difficult for the active metal to form a highly active hydrogenation phase, thus hindering the full realization of the catalyst's hydrogenation activity. Summary of the Invention

[0010] The purpose of this invention is to develop a deep hydrotreating catalyst for use in the deep hydrorefining process of diesel fuel. Under a reaction pressure not exceeding 8 MPa, the catalyst fully exerts its denitrification activity, reducing the nitrogen content in diesel fuel to below 20 μg / g. This provides low-nitrogen feedstock for catalysts prone to nitrogen poisoning, such as those used in diesel hydrotreating, diesel hydrodepthening, and diesel hydrocracking, ensuring the full utilization of catalyst activity and long-term stable operation.

[0011] To achieve the above objectives, the present invention provides a method for preparing a hydrodenitrification catalyst, the method comprising the following steps:

[0012] (1) Add AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2μm and alumina to deionized water, and emulsify by ultrasonication to obtain a carrier raw material slurry. The carrier raw material slurry is filtered, dried and ground to obtain a carrier raw material powder. The carrier raw material powder is mixed evenly with a molding aid, and then extruded, dried and calcined to obtain a catalyst carrier.

[0013] (2) A metal impregnation solution containing zinc, nickel and tungsten elements is dissolved in deionized water to obtain a metal impregnation solution. The catalyst support is impregnated by an equal volume impregnation method. After curing, drying and calcination, a hydrodenitrification catalyst is obtained.

[0014] In the preparation method of the hydrodenitrification catalyst of the present invention, in step (1), the amount of AlPO4-5 phosphorus aluminum molecular sieve added is 2 to 40 wt% of the weight of alumina.

[0015] In the preparation method of the hydrodenitrification catalyst of the present invention, in step (2), the content of each metal in the hydrodenitrification catalyst is calculated as its oxide, ZnO content is 1-10 wt% of the catalyst weight, NiO content is 1-10 wt% of the catalyst weight, and WO3 content is 10-30 wt% of the catalyst weight.

[0016] In the preparation method of the hydrodenitrification catalyst of the present invention, preferably, the ZnO content in the hydrodenitrification catalyst is 2-10 wt% of the catalyst weight, the NiO content is 2-10 wt% of the catalyst weight, and the WO3 content is 15-30 wt% of the catalyst weight.

[0017] The method for preparing the hydrodenitrification catalyst of the present invention, wherein the alumina has a specific surface area of ​​340-400 m². 2 / g, with a pore volume of 0.90~1.20mL / g.

[0018] The method for preparing the hydrodenitrification catalyst of the present invention uses an AlPO4-5 phosphorus aluminum molecular sieve with a specific surface area of ​​290-300 m². 2 / g, pore volume is 0.24~0.26mL / g.

[0019] The method for preparing the hydrodenitrification catalyst of the present invention includes a zinc-containing metal salt comprising at least one of zinc nitrate hexahydrate, zinc acetate, and zinc sulfate.

[0020] The method for preparing the hydrodenitrification catalyst of the present invention includes a nickel-containing metal salt comprising at least one of nickel nitrate hexahydrate, nickel acetate, and nickel sulfate.

[0021] The method for preparing the hydrodenitrification catalyst of the present invention includes a tungsten-containing metal salt comprising at least one of ammonium metatungstate, tungstic acid, and metatungstic acid.

[0022] The preparation method of the hydrodenitrification catalyst of the present invention includes ultrasonic emulsification with an ultrasonic frequency of 20000 Hz and an emulsification time of 0.5 to 2 h.

[0023] The method for preparing the hydrodenitrification catalyst of the present invention wherein the catalyst support is in the shape of one of the following: sheet-like, toothed spherical, Raschig ring, cylindrical bar, clover, and four-leaf clover, preferably cylindrical bar, clover, and four-leaf clover.

[0024] The method for preparing the hydrodenitrification catalyst of the present invention comprises a hydrodenitrification catalyst having a diameter of 0.8 mm to 2.0 mm as a thin strip or >2.5 mm as a coarse strip, preferably a diameter of 1.2 mm to 1.6 mm as a thin strip.

[0025] In the preparation method of the hydrodenitrification catalyst of the present invention, in step (2), the drying temperature is 100-140°C and the drying time is 2-5 hours; the calcination temperature is 400-500°C and the calcination time is 3-6 hours.

[0026] In the preparation method of the hydrodenitrification catalyst of the present invention, in step (1), the molding aid includes at least one of guar gum powder, nitric acid, and citric acid, and the amount of each molding aid added is 3% of the weight of alumina.

[0027] The present invention also provides a hydrodenitrification catalyst, which is obtained by the above preparation method.

[0028] The present invention also provides an application of a hydrodenitrification catalyst used in the hydrodenitrification reaction of diesel fuel.

[0029] The application of the hydrodenitrification catalyst of the present invention, wherein the diesel fuel includes at least one of straight-run diesel fuel, catalytic diesel fuel, and coking diesel fuel.

[0030] The application of the hydrodenitrogenation catalyst of the present invention involves a hydrodenitrogenation reaction at a temperature of 320–390°C, a reaction pressure of 4–7 MPa, and a space velocity of 1.0–2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 200–500:1; the nitrogen content of the hydrogenated diesel obtained from the hydrodenitrification reaction is less than 20 μg / g.

[0031] The preparation method of the hydrodenitrification catalyst of this invention uses AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2 μm. Compared with AlPO4-5 phosphorus aluminum molecular sieve with a larger crystal size, the smaller than 2 μm crystal size of this invention can increase the catalytic activity of the AlPO4-5 phosphorus aluminum molecular sieve. The ultrasonic emulsification method used in this invention enables more thorough mixing of AlPO4-5 phosphorus aluminum molecular sieve and alumina, improving the uniformity of material mixing and thus increasing the utilization efficiency of the AlPO4-5 phosphorus aluminum molecular sieve.

[0032] The preparation method of the hydrodenitrification catalyst of this invention involves introducing zinc into a metal impregnation solution. Zinc, along with other active metals, competitively adsorbs on the catalyst support surface to form a zinc-aluminum spinel structure. This adjusts the interaction forces between Ni, W, and the support, inhibits the formation of inert substances like nickel-aluminum spinel, promotes the formation of a highly active hydrogenation phase by the active metals, improves the utilization efficiency of the active metal Ni, and thus enhances the hydrodenitrification activity of the catalyst. The hydrodenitrification catalyst obtained by the preparation method of this invention has been evaluated for hydrotreating different feedstocks, and the process conditions for the deep hydrodenitrification reaction of different feedstocks have been optimized. This hydrodenitrification catalyst is suitable for the hydrodenitrification process of diesel fractions in the petroleum refining field and can produce low-nitrogen diesel with a nitrogen content of less than 20 μg / g. Attached Figure Description

[0033] Figure 1 The image shows the XRD pattern of the AlPO4-5 phosphorus aluminum molecular sieve used in this invention. Detailed Implementation

[0034] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples are all commercially available.

[0035] Raw materials and sources:

[0036] The alumina powder was purchased from Shandong Yuneng Catalyst Technology Co., Ltd., with a specific surface area of ​​360 m². 2 / g, pore volume 0.92mL / g;

[0037] The AlPO4-5 phosphorus aluminum molecular sieve was prepared in the laboratory, with a crystal size of less than 2 μm and a specific surface area of ​​290 m². 2 / g, pore volume is 0.24mL / g;

[0038] Zinc nitrate hexahydrate was purchased from Hubei Changxinsheng Chemical Co., Ltd., with a purity of 99 wt%; zinc acetate was purchased from Tianjin Kemio Chemical Reagent Co., Ltd., with a purity of 99 wt%.

[0039] Nickel nitrate hexahydrate was purchased from Xinxiang Chuangjia New Materials Co., Ltd., with a purity of 99 wt%.

[0040] Ammonium metatungstate was purchased from Henan Detai Chemical Products Co., Ltd., with a purity of 99 wt%.

[0041] Preparation Example 1:

[0042] Add 2 kg of deionized water to a 5 L stainless steel container. Take 800 g of alumina powder and 16 g of AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2 μm, and add them sequentially to the deionized water under stirring to form a slurry. After slurrying for 10 minutes, transfer the slurry to an ultrasonic emulsifier and emulsify at a frequency of 20000 Hz for 30 minutes. After filtering, drying, and grinding the slurry through an 180-mesh sieve, obtain the carrier raw material powder. Take 500 g of the carrier raw material powder, add 15 g of guar gum powder, mix evenly, and add dropwise a mixed solution consisting of 15 g of nitric acid (68 wt%), 15 g of citric acid, and 400 g of deionized water. Knead the mixture, extrude it into 1.5 mm clover-shaped strips, dry at 120 °C for 2 h, and then calcine at 550 °C for 4 h to produce carrier #1.

[0043] Preparation Example 2:

[0044] Add 2 kg of deionized water to a 5 L stainless steel container. Take 800 g of alumina powder and 32 g of AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2 μm, and add them sequentially to the deionized water under stirring to form a slurry. After slurrying for 10 minutes, transfer the slurry to an ultrasonic emulsifier and emulsify at a frequency of 20000 Hz for 30 minutes. After filtering, drying, and grinding the slurry through an 180-mesh sieve, obtain the carrier raw material powder. Take 500 g of the carrier raw material powder, add 15 g of guar gum powder, mix evenly, and add dropwise a mixed solution consisting of 15 g of nitric acid (68 wt%), 15 g of citric acid, and 400 g of deionized water. Knead the mixture, extrude it into 1.5 mm clover-shaped strips, dry at 120 °C for 2 h, and then calcine at 550 °C for 4 h to produce carrier #2.

[0045] Preparation Example 3:

[0046] Add 2 kg of deionized water to a 5 L stainless steel container. Take 800 g of alumina powder and 80 g of AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2 μm, and add them sequentially to the deionized water under stirring to form a slurry. After slurrying for 10 minutes, transfer the slurry to an ultrasonic emulsifier and emulsify at a frequency of 20000 Hz for 30 minutes. After filtering, drying, and grinding the slurry through an 180-mesh sieve, obtain the carrier raw material powder. Take 500 g of the carrier raw material powder, add 15 g of guar gum powder, mix evenly, and add dropwise a mixed solution consisting of 15 g of nitric acid (68 wt%), 15 g of citric acid, and 400 g of deionized water. Knead the mixture, extrude it into 1.5 mm clover-shaped strips, dry at 120 °C for 2 h, and then calcine at 550 °C for 4 h to produce carrier #3.

[0047] Preparation Example 4:

[0048] Add 2 kg of deionized water to a 5 L stainless steel container. Take 800 g of alumina powder and 160 g of AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2 μm, and add them sequentially to the deionized water under stirring to form a slurry. After slurrying for 10 minutes, transfer the slurry to an ultrasonic emulsifier and emulsify at a frequency of 20000 Hz for 30 minutes. After filtering, drying, and grinding the slurry through an 180-mesh sieve, obtain the carrier raw material powder. Take 500 g of the carrier raw material powder, add 15 g of guar gum powder, mix evenly, and add dropwise a mixed solution consisting of 15 g of nitric acid (68 wt%), 15 g of citric acid, and 400 g of deionized water. Knead the mixture, extrude it into 1.5 mm clover-shaped strips, dry at 120 °C for 2 h, and then calcine at 550 °C for 4 h to produce carrier #4.

[0049] Preparation Example 5:

[0050] Add 2 kg of deionized water to a 5 L stainless steel container. Take 800 g of alumina powder and 320 g of AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2 μm, and add them sequentially to the deionized water under stirring to form a slurry. After slurrying for 10 minutes, transfer the slurry to an ultrasonic emulsifier and emulsify at a frequency of 20000 Hz for 30 minutes. After filtering, drying, and grinding the slurry through a 180-mesh sieve, obtain the carrier raw material powder. Take 500 g of the carrier raw material powder, add 15 g of guar gum powder, mix evenly, and add dropwise a mixed solution consisting of 15 g of nitric acid (68 wt%), 15 g of citric acid, and 400 g of deionized water. Knead the mixture, extrude it into 1.5 mm clover-shaped strips, dry at 120 °C for 2 h, and then calcine at 550 °C for 4 h to produce carrier #5.

[0051] Preparation of Comparative Example 1:

[0052] The difference from Preparation Example 4 is that AlPO4-5 phosphorus aluminum molecular sieve was not added.

[0053] Take 500g of alumina powder and 15g of guar gum powder, mix them evenly, add dropwise a mixed solution consisting of 15g of nitric acid (68wt%), 15g of citric acid and 400g of deionized water, knead, extrude into 1.5mm clover shape, dry at 120℃ for 2h, and then calcine at 550℃ for 4h to prepare D1# carrier.

[0054] Preparation of Comparative Example 2:

[0055] The difference from Preparation Example 4 is that AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of 10 μm was added.

[0056] Add 2 kg of deionized water to a 5 L stainless steel container. Take 800 g of alumina powder and 160 g of AlPO4-5 phosphorus aluminate molecular sieve with a grain size of 10 μm, and add them sequentially to the deionized water under stirring to form a slurry. After slurrying for 10 minutes, transfer the slurry to an ultrasonic emulsifier and emulsify at a frequency of 20000 Hz for 30 minutes. After filtering, drying, and grinding the slurry through an 180-mesh sieve, obtain the carrier raw material powder. Take 500 g of the carrier raw material powder, add 15 g of guar gum powder, mix evenly, and add dropwise a mixed solution consisting of 15 g of nitric acid (68 wt%), 15 g of citric acid, and 400 g of deionized water. Knead the mixture, extrude it into 1.5 mm clover-shaped strips, dry at 120 °C for 2 h, and then calcine at 550 °C for 4 h to prepare the D2# carrier.

[0057] Evaluation Example 1:

[0058] More than 10g of each of supports #1-5 and #D1-D2 were impregnated in a Ni-W-Zn impregnation solution using an equal-volume impregnation method. The impregnated supports were then dried at 120℃ for 3 hours and calcined at 450℃ for 4 hours to prepare catalysts #1-5 and #D1-D2, respectively. The NiO content, WO3 content, and ZnO content in the catalysts were all 5 wt% by weight, 20 wt% by weight, and 1 wt% by weight, respectively.

[0059] A quinoline / decahydronaphthalene solution with a nitrogen content of 500 μg / g was used as a model compound for the hydrogenation denitrification reaction. The reaction was evaluated using a microreactor at a reaction pressure of 3 MPa, a reaction temperature of 330 °C, and a space velocity of 2.0 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 500, the denitrification activity of catalysts 1#-5# and D1#-D2# was investigated respectively. The experimental results are shown in Table 1.

[0060] Table 1. Hydrogenation and denitrification effects of catalysts #1-5 and #1-#2 on model compounds.

[0061]

[0062] The hydrogenation evaluation results of the model compounds in Table 1 show that the denitrification effects of catalysts D1#-D2# were poor due to the absence of AlPO4-5 phosphorus aluminum molecular sieve or the addition of AlPO4-5 phosphorus aluminum molecular sieve with a crystal size greater than 2μm. Catalyst 4# improved its catalytic activity and denitrification effect by using AlPO4-5 phosphorus aluminum molecular sieve with a crystal size less than 2μm, which is a feature of this invention.

[0063] Examples 1-7:

[0064] Catalysts with different NiO, WO3, and ZnO contents were prepared by impregnating Ni-W-Zn impregnation solution with support #4 using the equal-volume impregnation method. The supports impregnated with Ni-W-Zn metal solution were dried at 120℃ for 3 h and then calcined at 450℃ for 4 h to prepare catalysts #6-#12. A quinoline / decahydronaphthalene solution with a nitrogen content of 500 μg / g was used as a model compound for the hydrodenitrification reaction. The reaction was evaluated using a microreactor at a reaction pressure of 3 MPa, a reaction temperature of 330℃, and a space velocity of 2.0 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 500, the denitrification activity of catalysts 6#-12# was investigated respectively. The corresponding catalyst metal content and denitrification activity are shown in Table 2.

[0065] Comparative Example 1:

[0066] The difference from Examples 1-3 is that no Zn is added to the impregnation solution.

[0067] Catalysts with different NiO and WO3 contents were prepared by impregnating Ni-W impregnation solution with support #4 using the equal-volume impregnation method. The supports impregnated with Ni-W metal solution were dried at 120℃ for 3 h and then calcined at 450℃ for 4 h to obtain catalyst #3. A quinoline / decahydronaphthalene solution with a nitrogen content of 500 μg / g was used as a model compound for the hydrodenitrification reaction. The reaction was evaluated using a microreactor at a reaction pressure of 3 MPa, a reaction temperature of 330℃, and a space velocity of 2.0 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 500, the denitrification activity of the D3# catalyst was investigated. The corresponding catalyst metal content and denitrification activity are shown in Table 2.

[0068] Comparative Example 2:

[0069] The difference from Examples 4-6 is that no Zn is added to the impregnation solution.

[0070] Catalysts with different NiO and WO3 contents were prepared by impregnating Ni-W impregnation solution with support #4 using the equal-volume impregnation method. The support impregnated with Ni-W metal solution was dried at 120℃ for 3 h and then calcined at 450℃ for 4 h to obtain catalyst D4#. A quinoline / decahydronaphthalene solution with a nitrogen content of 500 μg / g was used as a model compound for the hydrodenitrification reaction. The reaction was evaluated using a microreactor at a reaction pressure of 3 MPa, a reaction temperature of 330℃, and a space velocity of 2.0 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 500, the denitrification activity of the D4# catalyst was investigated. The corresponding catalyst metal content and denitrification activity are shown in Table 2.

[0071] Comparative Example 3:

[0072] The difference from Example 7 is that no Zn is added to the impregnation solution.

[0073] Catalysts with different NiO and WO3 contents were prepared by impregnating Ni-W impregnation solution onto support #4 using an equal-volume impregnation method. The supports impregnated with Ni-W metal solution were dried at 120℃ for 3 h and then calcined at 450℃ for 4 h to obtain catalyst #5. A quinoline / decahydronaphthalene solution with a nitrogen content of 500 μg / g was used as a model compound for the hydrodenitrification reaction. The reaction was evaluated using a microreactor at a reaction pressure of 3 MPa, a reaction temperature of 330℃, and a space velocity of 2.0 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 500, the denitrification activity of the D5# catalyst was investigated. The corresponding catalyst metal content and denitrification activity are shown in Table 2.

[0074] Table 2. Evaluation of nitrogen removal rate by metal content and model compounds for catalysts #6-12 and D3-D5.

[0075]

[0076] As can be seen from the results in Table 2, compared with the catalyst without Zn, the catalyst with Zn added in this invention has a higher denitrification rate. This is because zinc competes with Ni and W on the surface of the catalyst support to form a zinc-aluminum spinel structure, which adjusts the interaction force between Ni and W and the support, inhibits the formation of inert substances such as nickel-aluminum spinel, promotes the formation of a highly active hydrogenation phase by the active metal, improves the utilization efficiency of the active metal Ni, and thus improves the hydrogenation and denitrification activity of the catalyst.

[0077] Example 8:

[0078] Using catalysts 10# and D4#, and with straight-run diesel, catalytic cracking diesel, coking diesel, or a mixture of the above diesel fractions from a certain refinery as feedstock, the hydrodenitrification effect of the catalysts on various diesel fractions under different process conditions was investigated. The results are shown in Table 3.

[0079] Table 3. Effects of catalysts on hydrodenitrogenation of different feedstocks under different conditions.

[0080]

[0081]

[0082] As can be seen from the results in Table 3, under different catalytic conditions, the catalyst with added Zn in this invention has a higher denitrification rate than the catalyst without added Zn. This confirms that zinc competes with Ni and W to adsorb on the catalyst support surface to form a zinc-aluminum spinel structure, which adjusts the interaction force between Ni and W and the support, inhibits the formation of inert substances such as nickel-aluminum spinel, promotes the formation of a highly active hydrogenation phase by the active metal, improves the utilization efficiency of the active metal Ni, and thus improves the hydrogenation and denitrification activity of the catalyst.

[0083] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for hydrodenitrification, characterized in that, The preparation method of the catalyst used in the hydrodenitrification method includes the following steps: (1) Add AlPO4-5 phosphorus aluminum molecular sieve with a crystal size of less than 2μm and alumina to deionized water, and emulsify by ultrasonication to obtain a carrier raw material slurry. The carrier raw material slurry is filtered, dried and ground to obtain a carrier raw material powder. The carrier raw material powder is mixed evenly with a molding aid, and then extruded, dried and calcined to obtain a catalyst carrier. (2) The metal salt containing zinc, nickel and tungsten elements is dissolved in deionized water to obtain a metal impregnation solution. The catalyst support is impregnated by the equal volume impregnation method. After curing, drying and calcination, a hydrodenitrification catalyst is obtained.

2. The method according to claim 1, characterized in that, In step (1), the amount of AlPO4-5 phosphorus aluminum molecular sieve added is 2 to 40 wt% of the weight of alumina.

3. The method according to claim 1, characterized in that, In step (2), in the hydrodenitrification catalyst, the content of each metal, calculated as its oxide, is 1-10 wt% ZnO, 1-10 wt% NiO, and 10-30 wt% WO3.

4. The method according to claim 3, characterized in that, In the hydrodenitrification catalyst, the ZnO content is 2-10 wt% of the catalyst weight, the NiO content is 2-10 wt% of the catalyst weight, and the WO3 content is 15-30 wt% of the catalyst weight.

5. The method according to claim 1, characterized in that, The specific surface area of ​​the alumina is 340–400 m². 2 / g, with a pore volume of 0.90~1.20mL / g.

6. The method according to claim 1, characterized in that, The specific surface area of ​​the AlPO4-5 phosphorus aluminum molecular sieve is 290-300 m². 2 / g, pore volume is 0.24~0.26 mL / g.

7. The method according to claim 1, characterized in that, The zinc-containing metal salt includes at least one of zinc nitrate hexahydrate, zinc acetate, and zinc sulfate; The nickel-containing metal salt includes at least one of nickel nitrate hexahydrate, nickel acetate, and nickel sulfate; The tungsten-containing metal salt includes at least one of ammonium metatungstate, tungstic acid, and metatungstic acid. The hydrodenitrification catalyst has a diameter of 0.8 mm to 2.0 mm in thin strips or >2.5 mm in coarse strips.

8. The application of a hydrodenitrification catalyst, characterized in that, The catalyst according to any one of claims 1-7 is used in the hydrodenitrification reaction of diesel fuel.

9. The application according to claim 8, characterized in that, The diesel fuel includes at least one of straight-run diesel, catalytic diesel, and coking diesel.

10. The application according to claim 8, characterized in that, The hydrodenitrification reaction is carried out at a temperature of 320–390 °C, a pressure of 4–7 MPa, and a space velocity of 1.0–2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 200–500:1; the nitrogen content of the hydrogenated diesel obtained from the hydrodenitrification reaction is less than 20 μg / g.

Images