Adsorbent denitrification agent and its use in hydrocracking processes

Abstract

The application discloses an adsorption denitrogenation agent and application thereof in a hydrocracking process. The adsorption denitrogenation agent comprises a molecular sieve and a modifier; the modifier comprises a molecular sieve surface treatment agent and an organic acid. The application is a one-stage series hydrocracking process, and the method comprises the following steps: raw oil and hydrogen are sequentially subjected to hydrofining, adsorption denitrogenation and hydrocracking to obtain a hydrocracking product, and the adsorption denitrogenation adopts the adsorption denitrogenation agent. The application of the adsorption denitrogenation agent in the hydrocracking process can effectively adsorb and remove ammonia and macromolecular nitrides in the hydrofining product, so that the performance of a hydrocracking catalyst can be fully ensured to be stably exerted.

Description

Technical Field

[0001] This invention relates to the field of hydrocracking technology, specifically to an adsorption denitrification agent and its application in the hydrocracking process. Background Technology

[0002] The hydrocracking process converts heavy, low-quality feedstock into lighter products. The hydrocracking catalyst is a bifunctional catalyst possessing both acidic and active metal sites. Deactivation is primarily caused by nitrogen poisoning, coking, and other factors. Nitrogen poisoning is mainly related to the nitrogen content in the feedstock and the hydrorefined products, and catalyst deactivation affects the operating cycle. Therefore, effectively removing nitrogen oxides is crucial for extending the operating cycle of the hydrocracking catalyst.

[0003] A typical hydrocracking unit consists of a hydrorefining reactor and a hydrocracking reactor. The hydrorefining reactor mainly performs reactions such as hydrodesulfurization, hydrodenitrogenation, hydrodemetallization, and aromatic saturation. The hydrorefining products contain H2S, NH3, unremoved nitrogen oxides and sulfides, and feedstock components. Among these, NH3 and unremoved nitrogen oxides significantly affect the activity of the hydrocracking catalyst, thus impacting the unit's operating cycle. NH3 primarily adsorbs onto the acidic sites of the hydrocracking catalyst, preventing the adsorption of feedstock components and inhibiting catalyst activity. Unremoved nitrogen oxides are both large-molecule basic and non-basic nitrogen oxides; both can clog the pores of the hydrocracking catalyst, causing rapid deactivation that is difficult to restore, severely impacting catalyst performance and leading to a significantly shortened operating cycle.

[0004] When hydrocracking units process feedstocks with high nitrogen content, the products obtained after hydrorefining contain large amounts of ammonia and unremoved large molecular nitrogen compounds, which significantly impacts the performance of hydrocracking catalysts. Currently, refineries generally mitigate the harmful effects of large molecular nitrogen compounds by increasing the amount of hydrocracking catalyst loaded. However, this leads to the permanent deactivation of some hydrocracking catalysts, impairing their performance, increasing catalyst investment costs, and reducing the company's economic benefits.

[0005] CN106987268B discloses a coking wax oil adsorption denitrification catalyst. The catalyst uses inorganic acids such as sulfuric acid, nitric acid, nitrous acid, chloric acid, perchloric acid, hydrochloric acid, and phosphoric acid as acidic agents, copper nitrate, ferric nitrate, silver nitrate, and chromium nitrate as transition metal salts as complexes, and pseudoboehmite, activated carbon, and silica gel as supports. This method can only perform adsorption denitrification on feedstock oils with a low distillation range, and the adsorption denitrification effect is limited. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an adsorption denitrification agent and its application in the hydrocracking process. The application of this adsorption denitrification agent in the hydrocracking process can effectively adsorb and remove ammonia and large molecular nitrogen compounds from the hydrorefining products, thereby ensuring the stable performance of the hydrocracking catalyst.

[0007] The first aspect of the present invention provides an adsorption denitrification agent, the adsorption denitrification agent comprising a molecular sieve and a modifier; the modifier comprising a molecular sieve surface treatment agent and an organic acid.

[0008] In this invention, when the adsorption denitrification agent is used to adsorb and remove organic nitrogen-containing compounds, adsorption denitrification agent A is used.

[0009] In this invention, the denitrifying agent A comprises molecular sieve A and modifier A. The molecular sieve A is selected from at least one of ZSM series molecular sieves, mordenite zeolite, and 5A molecular sieves, preferably at least one of ZSM series and 5A molecular sieves. The ZSM series molecular sieve is selected from at least one of ZSM-5, ZSM-22, and ZSM-48. In the molecular sieve A, the amount of medium-strong acid accounts for more than 20% of the total acid amount of the molecular sieve, preferably 50% to 70%; the pore volume of micropores (<2nm) in the pore structure distribution accounts for more than 10% of the total pore volume, preferably 50% to 80%. The modifier A comprises molecular sieve surface treatment agent A and organic acid A. The molecular sieve surface treatment agent A is selected from one or more of trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, and methyldiphenylhydroxyethylsilane, preferably one or more of trimethylchlorosilane, vinyltrichlorosilane, and methyldiphenylhydroxyethylsilane. The organic acid A is selected from one or more of 2,5-dichloroisonicotinic acid, 3,5-dichloroisonicotinic acid, 2-methoxy-3-methylisonicotinic acid, 3-ethylisonicotinic acid, and 3-aminoisonicotinic acid, preferably one or more of 3-ethylisonicotinic acid, 2,5-dichloroisonicotinic acid, and 2-methoxy-3-methylisonicotinic acid.

[0010] In this invention, preferably, the denitrifying agent A contains, by mass parts,

[0011] Molecular sieve A: 50–95 parts;

[0012] Molecular sieve surface treatment agent A: 5-30 parts;

[0013] Organic acid A: 7-50 parts.

[0014] In this invention, preferably, the denitrifying agent A contains, by mass parts,

[0015] Molecular sieve A: 60-80 parts;

[0016] Molecular sieve surface treatment agent A: 8-20 parts;

[0017] 3-Ethylisonicotinic acid: 3-20 parts, preferably 5-15 parts;

[0018] 2,5-Dichloroisonicotinic acid: 2-15 parts, preferably 5-10 parts;

[0019] 2-Methoxy-3-methylisonicotinic acid: 2-15 parts, preferably 5-10 parts.

[0020] In this invention, the preparation method of denitrifying agent A includes: mixing molecular sieve A and modifier A, and heating to 75–210°C, preferably 120–190°C, under an inert atmosphere (such as nitrogen) for 30–480 min, preferably 120–400 min; obtaining modified molecular sieve A, then molding the modified molecular sieve A, and drying it after molding (preferably, the drying conditions are as follows: drying temperature 100–120°C, drying time 200–500 min) to obtain denitrifying agent A. During the molding process, conventional molding aids, such as binders and extrusion aids, can be added. Molding can be done by extrusion molding. The binder can be small-pore alumina, and the extrusion aid can be guar gum powder.

[0021] In this invention, when the adsorption denitrification agent is used to adsorb and remove ammonia, adsorption denitrification agent B is used.

[0022] In this invention, the denitrifying agent B comprises molecular sieve B and modifier B. The molecular sieve B is selected from at least one of Y-type molecular sieves, X-type molecular sieves, Beta molecular sieves, and ITQ series molecular sieves. The ITQ series molecular sieve is selected from at least one of ITQ-7, ITQ-43, ITQ-12, and ITQ-37. In the molecular sieve B, the amount of medium-strong acid accounts for less than 50% of the total acid amount of the molecular sieve, preferably 20% to 40%; in the pore structure distribution, the mesopores and macropores (>2nm) account for more than 20% of the total pore volume, preferably 30% to 70%. The modifier B comprises molecular sieve surface treatment agent B and organic acid B. The molecular sieve surface treatment agent B is selected from one or more of trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, methyldiphenylhydroxyethylsilane, methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate, preferably one or more of methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate. The organic acid B is selected from one or more of 3,4-thiophene dicarboxylic acid, dithiodicarboxylic acid, m-nitrodicarboxylic acid, diethylmalonic acid, dimercaptosuccinic acid, 3-aminoisonicotinic acid, and 3-ethylisonicotinic acid, preferably one or more of 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, and m-nitrodicarboxylic acid.

[0023] In this invention, preferably, the adsorption denitrification agent B, by mass parts,

[0024] Molecular sieve B: 50–95 parts;

[0025] Molecular sieve surface treatment agent B: 5-30 parts;

[0026] Organic acid B: 14-65 parts.

[0027] In this invention, preferably, the adsorption denitrification agent B, by mass parts,

[0028] Molecular sieve B: 60-80 parts;

[0029] Molecular sieve surface treatment agent B: 8-20 parts;

[0030] 3-Aminoisonicotinic acid: 10-20 parts;

[0031] 3,4-Thiophene dicarboxylic acid: 5–15 parts;

[0032] m-Nitrodicarboxylic acid: 5-10 parts.

[0033] In this invention, the preparation method of the adsorption denitrifying agent B includes: mixing molecular sieve B with modifier B, heating to 75–210°C, preferably 120–190°C, under an inert atmosphere (such as nitrogen), for a treatment time of 30–480 min, preferably 120–360 min, to obtain modified molecular sieve B; then molding the modified molecular sieve B; and finally drying it (preferably, the drying conditions are as follows: drying temperature of 100–120°C, drying time of 200–500 min) to obtain denitrifying agent B. During the molding process, conventional molding aids, such as binders and extrusion aids, can be added. Molding can be performed by extrusion molding. The binder can be small-pore alumina, and the extrusion aid can be guar gum powder.

[0034] The second aspect of this invention provides a method for improving the operational stability of a hydrocracking unit, employing a single-stage series hydrocracking process. The method includes: feedstock oil and hydrogen being sequentially subjected to hydrorefining, adsorption denitrification, and hydrocracking to obtain hydrocracking products; wherein the mass content of organic nitrogen-containing compounds in the hydrorefining products is 10 ppm or more, preferably 15 ppm or more, and the mass content of ammonia is 500 ppm or more, preferably 800 ppm or more, and the adsorption denitrification uses the aforementioned adsorption denitrification agent.

[0035] In this invention, the adsorption denitrification is carried out using a container filled with an adsorption denitrification agent. This can be a separately installed adsorption reactor or a logistics pipeline filled with an adsorption denitrification agent, preferably a logistics pipeline filled with an adsorption denitrification agent.

[0036] In this invention, the mass content of organic nitrogen-containing compounds in the hydrogenated product is 10ppm to 200ppm, preferably 15ppm to 120ppm, and the mass content of ammonia is 500ppm to 5000ppm, preferably 800ppm to 3800ppm.

[0037] In this invention, the adsorption denitrification agent includes adsorption denitrification agent A and adsorption denitrification agent B. The hydrorefined product first contacts denitrification agent A and then contacts denitrification agent B.

[0038] In this invention, the denitrifying agent A comprises molecular sieve A and modifier A. The molecular sieve A is selected from at least one of ZSM series molecular sieves, mordenite zeolite, and 5A molecular sieves, preferably at least one of ZSM series and 5A molecular sieves. The ZSM series molecular sieve is selected from at least one of ZSM-5, ZSM-22, and ZSM-48. In the molecular sieve A, the amount of medium-strong acid accounts for more than 20% of the total acid amount of the molecular sieve, preferably 50% to 70%; the pore volume of micropores (<2nm) in the pore structure distribution accounts for more than 10% of the total pore volume, preferably 50% to 80%. The modifier A comprises molecular sieve surface treatment agent A and organic acid A. The molecular sieve surface treatment agent A is selected from one or more of trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, and methyldiphenylhydroxyethylsilane, preferably one or more of trimethylchlorosilane, vinyltrichlorosilane, and methyldiphenylhydroxyethylsilane. The organic acid A is selected from one or more of 2,5-dichloroisonicotinic acid, 3,5-dichloroisonicotinic acid, 2-methoxy-3-methylisonicotinic acid, 3-ethylisonicotinic acid, and 3-aminoisonicotinic acid, preferably one or more of 3-ethylisonicotinic acid, 2,5-dichloroisonicotinic acid, and 2-methoxy-3-methylisonicotinic acid.

[0039] In this invention, preferably, the denitrifying agent A contains, by mass parts,

[0040] Molecular sieve A: 50–95 parts;

[0041] Molecular sieve surface treatment agent A: 5-30 parts;

[0042] Organic acid A: 7-50 parts.

[0043] In this invention, preferably, the denitrifying agent A contains, by mass parts,

[0044] Molecular sieve A: 60-80 parts;

[0045] Molecular sieve surface treatment agent A: 8-20 parts;

[0046] 3-Ethylisonicotinic acid: 3-20 parts, preferably 5-15 parts;

[0047] 2,5-Dichloroisonicotinic acid: 2-15 parts, preferably 5-10 parts;

[0048] 2-Methoxy-3-methylisonicotinic acid: 2-15 parts, preferably 5-10 parts.

[0049] In this invention, the preparation method of denitrifying agent A includes: mixing molecular sieve A and modifier A, and heating to 75–210°C, preferably 120–190°C, under an inert atmosphere (such as nitrogen) for 30–480 min, preferably 120–400 min; obtaining modified molecular sieve A, then molding the modified molecular sieve A, and drying it after molding (preferably, the drying conditions are as follows: drying temperature 100–120°C, drying time 200–500 min) to obtain denitrifying agent A. During the molding process, conventional molding aids, such as binders and extrusion aids, can be added. Molding can be done by extrusion molding. The binder can be small-pore alumina, and the extrusion aid can be guar gum powder.

[0050] In this invention, the denitrifying agent B comprises molecular sieve B and modifier B. The molecular sieve B is selected from at least one of Y-type molecular sieves, X-type molecular sieves, Beta molecular sieves, and ITQ series molecular sieves. The ITQ series molecular sieve is selected from at least one of ITQ-7, ITQ-43, ITQ-12, and ITQ-37. In the molecular sieve B, the amount of medium-strong acid accounts for less than 50% of the total acid amount of the molecular sieve, preferably 20% to 40%; in the pore structure distribution, the mesopores and macropores (>2nm) account for more than 20% of the total pore volume, preferably 30% to 70%. The modifier B comprises molecular sieve surface treatment agent B and organic acid B. The molecular sieve surface treatment agent B is selected from one or more of trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, methyldiphenylhydroxyethylsilane, methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate, preferably one or more of methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate. The organic acid B is selected from one or more of 3,4-thiophene dicarboxylic acid, dithiodicarboxylic acid, m-nitrodicarboxylic acid, diethylmalonic acid, dimercaptosuccinic acid, 3-aminoisonicotinic acid, and 3-ethylisonicotinic acid, preferably one or more of 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, and m-nitrodicarboxylic acid.

[0051] In this invention, preferably, the adsorption denitrification agent B, by mass parts,

[0052] Molecular sieve B: 50–95 parts;

[0053] Molecular sieve surface treatment agent B: 5-30 parts;

[0054] Organic acid B: 14-65 parts.

[0055] In this invention, preferably, the adsorption denitrification agent B, by mass parts,

[0056] Molecular sieve B: 60-80 parts;

[0057] Molecular sieve surface treatment agent B: 8-20 parts;

[0058] 3-Aminoisonicotinic acid: 10-20 parts;

[0059] 3,4-Thiophene dicarboxylic acid: 5–15 parts;

[0060] m-Nitrodicarboxylic acid: 5-10 parts.

[0061] In this invention, the preparation method of the adsorption denitrifying agent B includes: mixing molecular sieve B with modifier B, heating to 75–210°C, preferably 120–190°C, under an inert atmosphere (such as nitrogen), for a treatment time of 30–480 min, preferably 120–360 min, to obtain modified molecular sieve B; then molding the modified molecular sieve B; and finally drying it (preferably, the drying conditions are as follows: drying temperature of 100–120°C, drying time of 200–500 min) to obtain denitrifying agent B. During the molding process, conventional molding aids, such as binders and extrusion aids, can be added. Molding can be performed by extrusion molding. The binder can be small-pore alumina, and the extrusion aid can be guar gum powder.

[0062] In this invention, the volume ratio of adsorbent A to adsorbent B is 0.5:1 to 5:1, preferably 0.8:1 to 3:1.

[0063] In this invention, the total filling volume of adsorbent A and adsorbent B in the logistics pipeline accounts for 5%-90% of the effective logistics pipeline volume, preferably 10%-60%.

[0064] In this invention, the volume between the outlet of the hydrorefining reactor and the pre-contact surface of the adsorbent A is 5% to 50% of the effective stream pipeline volume, preferably 10% to 20%; the volume between the post-contact surface of the adsorbent B and the inlet of the hydrocracking reactor is 5% to 50% of the effective stream pipeline volume, preferably 10% to 20%; and stainless steel mesh and fixing devices are respectively installed on the pre-contact surface of the adsorbent A and the post-contact surface of the adsorbent B to ensure that the adsorbent can stably exist in the stream pipeline during normal operation of the device. The mesh size of the stainless steel mesh is generally 5 to 40 meshes, preferably 10 to 20 meshes.

[0065] In this invention, the operating conditions for adsorption denitrification are: adsorption temperature of 100–450℃, preferably 300–370℃; pressure of 3.0–20.0 MPa, preferably 10–18 MPa; and volume hourly space velocity of 0.1–20 h⁻¹. -1 Preferably 0.5 to 15 hours -1 .

[0066] In this invention, the feedstock oil can be at least one of vacuum-pressed wax oil, coking wax oil, fluidized bed wax oil, deasphalted oil, and slurry bed wax oil. The nitrogen content of the feedstock oil is greater than 300 ppm, preferably 1200–4000 ppm.

[0067] In this invention, a single-stage tandem hydrocracking process is employed, typically comprising a hydrorefining reactor and a hydrocracking reactor. The hydrorefining reactor is filled with a conventional hydrorefining catalyst to remove impurities such as sulfur and nitrogen from the feedstock. The hydrocracking reactor is filled with a conventional hydrocracking catalyst for the hydrocracking of the feedstock to produce light oil products, such as at least one of naphtha, diesel, and kerosene. Hydrocracking technology that primarily produces heavy naphtha is generally preferred.

[0068] In this invention, when a flow pipeline filled with adsorbent denitrification agent is set between the hydrorefining product outlet of the hydrorefining reactor and the feed inlet of the hydrocracking reactor, the fixing device can be combined with the inner wall of the pipeline by welding, and the fixing device is fixed to the stainless steel mesh with screws to ensure that the position of the adsorbent denitrification agent is fixed and does not move.

[0069] In this invention, the operating conditions for hydrorefining are as follows: reaction temperature is 300℃~420℃, preferably 310℃~390℃; reactor inlet pressure is 6MPa~20MPa, preferably 8MPa~19MPa; and volume hourly space velocity is 0.3h. -1 ~3.0h -1 0.4h is preferred -1 ~2.5h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–1200, preferably 500–1100.

[0070] In this invention, the operating conditions for hydrocracking are as follows: reaction temperature is 350℃~435℃, preferably 360℃~430℃; reactor inlet pressure is 6MPa~20MPa, preferably 8MPa~19MPa; volume hourly space velocity is 0.5h. -1 ~5.0h -1 0.6h is preferred -1 ~3.0h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–2000, preferably 500–1100. Generally, the hydrocracking reaction temperature in the later stages of operation is 380℃–430℃.

[0071] In this invention, the hydrorefining catalyst used is a hydrocracking pretreatment catalyst, comprising a support and a supported hydrogenation metal. Based on the weight of the catalyst, it typically includes a Group VIB metal component (such as tungsten and / or molybdenum) in the periodic table, with a mass content of 10%–35% (based on oxides), preferably 15%–30%; and a Group VIII metal (such as nickel and / or cobalt) in the mass content of 1%–7% (based on oxides), preferably 1.5%–6%. The support is an inorganic refractory oxide, generally selected from at least one of alumina, amorphous aluminum silicate, silica, and titanium dioxide. This type of catalyst preferably uses a Mo-Ni metal combination with a specific surface area ≥160 m². 2 / g, pore volume ≥0.3mL / g. The conventional hydrocracking pretreatment catalyst can be any of the existing commercial catalysts, such as the 3936, 3996, FF-16, FF-26, FF-36, FF-46, and FF-66 catalysts developed by the Fushun Petrochemical Research Institute (FRIPP); alternatively, the required catalyst can be prepared according to common knowledge in the field. The refining reaction is a process for removing impurities such as desulfurization, denitrification, and aromatic saturation.

[0072] In this invention, the hydrocracking catalyst used in hydrocracking comprises a cracking component and a hydrogenation component, and may also include a binder component. The cracking component typically comprises at least one amorphous silica-alumina and / or molecular sieve, such as Y-type, β-type, or USY molecular sieves. The binder is typically alumina and / or silica. The hydrogenation component is selected from at least one metal, metal oxide, or metal sulfide from Group VIB, Group VIIB, or Group VIII. The hydrogenation metal is preferably one or more of iron, chromium, molybdenum, tungsten, cobalt, and nickel. Based on the weight of the catalyst, the hydrogenation metal content, calculated as oxide, is 5%–40%, preferably 10%–35%, the molecular sieve content is 40% or more, preferably 40%–70%, and the remainder is amorphous silica-alumina and / or alumina components. Conventional hydrocracking catalysts can be selected from various existing commercial catalysts, such as the FC-46, FC-52, and FC-76 catalysts developed by FRIPP. Specific hydrocracking catalysts can also be prepared as needed according to common knowledge in the art.

[0073] In this invention, the adsorption denitrification can be operated in a multi-group parallel switchable manner. When using material pipelines, multiple switchable material pipelines can be set up. When the nitrogen removal capacity of the denitrifying agent in the current material pipeline reaches saturation, another material pipeline can be switched to perform the denitrification operation to ensure the continuous operation of nitrogen removal. Switching material pipelines can be selected by switching valves.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] 1. Based on a conventional single-stage tandem hydrocracking process, this invention involves adsorption denitrification of the product from the hydrorefining reactor before it enters the hydrocracking reactor. The product sequentially passes through adsorption denitrification agent A and adsorption denitrification agent B along the feed direction. Large molecular weight nitrogen compounds and ammonia in the hydrorefining product are removed by adsorption. For nitrogen compounds with low content and large molecular size, adsorption denitrification agent A is mainly used; for ammonia with high content and small molecular size, adsorption denitrification agent B is mainly used, effectively removing nitrogen from the hydrorefining product.

[0076] 2. In this invention, the adsorption denitrification agent A is a molecular sieve with a high proportion of micropores and a high content of medium-strong acid. It takes advantage of the characteristics that macromolecular nitrides are easy to bind to acidic sites and are not easy to desorb. At the same time, it takes advantage of the large molecular size of macromolecular nitrides to confine them to the micropore channels of the molecular sieve, so that the lower catalyst channels of the whole are blocked. Modifier A uses a silane coupling agent with a high silicon content, which allows multiple silanol groups in the molecule to combine with the silane coupling agent, increasing the stability of the silane coupling agent. The organic acid selected is a macromolecular isonicotinic acid-like substance. The nitrogen in isonicotinic acid can form strong hydrogen bonds with the hydrogen in the silane coupling agent, making the molecular sieve-silane coupling agent-isonicotinic acid system more stable overall. The macromolecular isonicotinic acid can further increase the micropore size on the basis of a high micropore ratio in the molecular sieve, making it easier for macromolecular nitrogen compounds to clog the micropore channels, minimizing the possibility of feedstock oil components entering the molecular sieve channels. Furthermore, the aromatic ring structure of the nitrogen in isonicotinic acid forms a large π-bond conjugated system with the aromatic ring structure of the macromolecular nitrogen compounds, significantly increasing the adsorption capacity for macromolecular nitrogen compounds, making them less prone to desorption. In addition, isonicotinic acid can also adsorb some ammonia.

[0077] 3. The adsorption and denitrification agent B in this invention is a molecular sieve with a high mesoporous ratio and numerous strong acid sites. It utilizes the characteristics of NH3 binding to acidic sites and its resistance to desorption at low temperatures. Furthermore, the ammonia partial pressure in the feed stream is relatively high, making it easier for NH3 to bind to strong acidic sites compared to the large-molecule aromatic components in the feedstock. The high mesoporous ratio allows feedstock components to pass through the catalyst bed more easily without accumulation, ensuring the yield of the feed stream entering the hydrocracking reactor. Modifier B uses a silane coupling agent with a low silicon content, which allows individual silanol groups in the molecule to combine with the silane coupling agent, increasing the number of silane coupling agents bound to the molecular sieve, thereby increasing the number of binding sites with organic acids. The organic acids selected are small-molecule isonicotinic acid and dibasic organic acids. The nitrogen in isonicotinic acid can form strong hydrogen bonds with the hydrogen in the silane coupling agent, making the molecular sieve-silane coupling agent-isonicotinic acid system more stable. Small-molecule isonicotinic acid occupies less space in the mesoporous molecular sieve, maximizing the permeability of the raw oil components. Dibasic organic acids contain elements such as sulfur and nitrogen, which can form hydrogen bonds with the silane coupling agent and isonicotinic acid to increase stability. In addition, dibasic acids have more acidic sites, which can adsorb more ammonia molecules.

[0078] 4. In this invention, the adsorption denitrification agent can be designed in multiple parallel groups, and the switchable method can ensure continuous operation of the device, making the process convenient and efficient. Attached Figure Description

[0079] Figure 1 A schematic diagram of a hydrocracking unit and the loading of adsorption denitrification catalyst;

[0080] The annotations in the attached figures are explained as follows:

[0081] 1-Feedstock oil and hydrogen, 2-Hydrorefining reactor, 3-Logistics pipeline, 4-Logistics pipeline, 5-Adsorption denitrification agent A, 6-Adsorption denitrification agent B, 7-Hydrocracking reactor, 8-Hydrocracking reaction products. Detailed Implementation

[0082] The method of the present invention will be described in more detail below with reference to specific embodiments and comparative examples.

[0083] The method of the present invention is as follows Figure 1 As shown, a series hydrocracking process is adopted. The method includes: feedstock oil and hydrogen 1 are sequentially hydrorefined in hydrorefining reactor 2, adsorbent denitrification in feedstock pipeline 3 or feedstock pipeline 4, and hydrocracking in hydrocracking reactor 7 to obtain hydrocracking product 8. Feedstock pipeline 3 and feedstock pipeline 4 are designed to be connected in parallel and switchable. Adsorbent denitrifier A5 and adsorbent denitrifier B6 are sequentially arranged in feedstock pipeline 3 or feedstock pipeline 4 along the feed direction.

[0084] In this invention, the acid content of the molecular sieve in the medium-strong acid category is determined using the NH3-programmed temperature desorption (NH3-TPD) method. The NH3-TPD characterization method is used to determine the acid content of the molecular sieve, and this method employs a Micromertics 2920 multi-functional adsorption instrument. The molecular sieve sample is compressed into a tablet, placed in a U-shaped tube, and pretreated at 400℃ for 0.5 h in a N2 atmosphere. Then, the temperature is lowered to 60℃ to allow the sample to saturate with NH3 adsorption, followed by physical desorption. The acid strength of the molecular sieve is determined according to the desorption temperature. Desorption peaks at (100–200)℃ are defined as weak acid centers, those at (200–350)℃ are assigned to medium-strong acid centers, and those at (350–600)℃ are assigned to strong acid centers. The desorption curves of each molecular sieve were processed by peak separation according to the principle of highest fitting degree. The acid amount was calculated based on the peak area and the amount of ammonia desorbed. The proportions of weak acid, medium strong acid and strong acid in the overall acidity distribution of the molecular sieve were calculated respectively.

[0085] In this invention, the pore size distribution is determined using the N2 adsorption-desorption method to assess the pore structure of the molecular sieve. This method employs an ASAP 2400 automated adsorption analyzer manufactured by Micromertics, USA. The molecular sieve is first treated under vacuum at 250℃ and 1.33 Pa for 4 hours, using N2 as the adsorbate, adsorbing at -196℃ and reaching static adsorption equilibrium. The specific surface area of ​​the molecular sieve is calculated using the BET equation, and the pore size distribution is determined using the BJH model method.

[0086] In this invention, the organic nitrogen content in the refined product is determined using petrochemical industry standard methods SH / T0657-2007 and SH / T0704-2010.

[0087] In this invention, the ammonia content in the refined product is determined using the national environmental protection standard HJ-535-2009.

[0088] Example 1

[0089] Preparation method of denitrification adsorbent A: ZSM-5 molecular sieve A is selected, and the amount of medium strong acid accounts for 53% of the total acid content of the molecular sieve; the pore volume of micropores (<2nm) in the pore structure distribution accounts for 55% of the total pore volume.

[0090] Modifier A composition: Molecular sieve surface treatment agent A is trimethylchlorosilane, vinyltrichlorosilane, and methyldiphenylhydroxyethylsilane, with a mass fraction ratio of 4:2:1; Organic acid A is 3-ethylisonicotinic acid, 2,5-dichloroisonicotinic acid, and 2-methoxy-3-methylisonicotinic acid, with a mass fraction ratio of 1.5:1:1.

[0091] Molecular sieve A and modifier A are mixed, wherein, by mass fraction, molecular sieve surface treatment agent A is 17 parts, organic acid A is 22 parts, and molecular sieve A is 61 parts. The mixture is heated to 140℃ for 140 minutes under a nitrogen atmosphere to obtain modified molecular sieve A. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve A is 89%, and the binder and extrusion aid account for 11% by mass. The mixture is then extruded into strips. After molding, it is dried at 110℃ for 480 minutes to obtain denitrifying agent A.

[0092] Preparation method of denitrification adsorbent B: Y-type molecular sieve is selected for molecular sieve B, and the amount of medium strong acid accounts for 23% of the total acid amount of molecular sieve; the pore structure distribution of mesopores and macropores (>2nm) accounts for 41% of the total pore volume.

[0093] Modifier B composition: Molecular sieve surface treatment agent B is methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl) acetate, with a mass fraction ratio of 3:2:0.5; Organic acid B is 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, and m-nitrodicarboxylic acid, with a mass fraction ratio of 2:2:1.

[0094] Molecular sieve B and modifier B are mixed, wherein, by mass percentage, molecular sieve surface treatment agent B is 10 parts, organic acid B is 30 parts, and molecular sieve B is 60 parts. The mixture is heated to 138℃ for 150 minutes under a nitrogen atmosphere to obtain modified molecular sieve B. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve B is 89%, and the binder and extrusion aid account for 11% by mass. The mixture is then extruded into strips. After extrusion, the strips are dried at 110℃ for 360 minutes to obtain denitrifying agent B.

[0095] Adopting such Figure 1 The process shown employs a single-stage tandem hydrocracking process. Adsorption denitrification is carried out via a feed pipeline, with denitrifying agent A and denitrifying agent B being loaded sequentially along the feed direction. The properties of the feedstock are shown in Table 1. The reaction conditions and results are shown in Table 2.

[0096] Example 2

[0097] Preparation method of denitrification adsorbent A: Molecular sieve A is selected as 5A molecular sieve, and the amount of medium strong acid accounts for 68% of the total acid content of molecular sieve; in the pore structure distribution, the micropores (<2nm) account for 67% of the total pore volume.

[0098] Modifier A composition: Molecular sieve surface treatment agent A is trimethylchlorosilane, vinyltrichlorosilane, and trimethylethoxysilane, with a mass fraction ratio of 2:3:2; Organic acid A is 3-ethylisonicotinic acid, 3-aminoisonicotinic acid, and 2-methoxy-3-methylisonicotinic acid, with a mass fraction ratio of 2:1:3.

[0099] Molecular sieve A and modifier A are mixed, wherein, by mass fraction, molecular sieve surface treatment agent A is 25 parts, organic acid A is 25 parts, and molecular sieve A is 50 parts. Under a nitrogen atmosphere, the mixture is heated to 142°C for 402 min to obtain modified molecular sieve A. Then, binder microporous alumina and extrusion aid guar powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve A is 91%, and the binder and extrusion aid account for 9% by mass fraction. The mixture is extruded into strips and dried at 105°C for 280 min to obtain denitrifying agent A.

[0100] Preparation method of denitrification adsorbent B: Beta molecular sieve is selected for molecular sieve B, with medium strong acid accounting for 37% of the total acid content of molecular sieve; the pore structure distribution of mesopores and macropores (>2nm) accounts for 32% of the total pore volume.

[0101] Modifier B composition: Molecular sieve surface treatment agent B is trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl) acetate, vinyltriacetoxysilane, and methyltrichlorosilane, with a mass fraction ratio of 4:1:2; Organic acid B is 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, and 3-ethylisonicotinic acid, with a mass fraction ratio of 1:1.5:3.

[0102] Molecular sieve B and modifier B are mixed, wherein, by mass fraction, molecular sieve surface treatment agent B is 25 parts, organic acid B is 15 parts, and molecular sieve B is 60 parts. Under a nitrogen atmosphere, the mixture is heated to 138°C for 390 minutes to obtain modified molecular sieve B. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve B is 90%, and the binder and extrusion aid account for 10% of the mass fraction of modified molecular sieve B. The mixture is extruded and then dried at 100°C for 300 minutes to obtain denitrifying agent B.

[0103] Adopting such Figure 1 The process shown employs a single-stage tandem hydrocracking process. Adsorption denitrification is carried out via a feed pipeline, with denitrifying agent A and denitrifying agent B being loaded sequentially along the feed direction. The properties of the feedstock are shown in Table 1. The reaction conditions and results are shown in Table 2.

[0104] Example 3

[0105] Preparation method of denitrification adsorbent A: ZSM-22 molecular sieve is selected for molecular sieve A, and the amount of medium strong acid accounts for 50% of the total acid content of the molecular sieve; the pore volume of micropores (<2nm) in the pore structure distribution accounts for 50% of the total pore volume.

[0106] Modifier A composition: Molecular sieve surface treatment agent A is trimethylchlorosilane, vinyltrichlorosilane, and vinyltriacetoxysilane, with a mass fraction ratio of 3:5:1; Organic acid A is 3-ethylisonicotinic acid, 3-aminoisonicotinic acid, 2-methoxy-3-methylisonicotinic acid, 2,5-dichloroisonicotinic acid, and 3,5-dichloroisonicotinic acid, with a mass fraction ratio of 1:1.5:2.4:3:2.

[0107] Molecular sieve A and modifier A are mixed, wherein, by mass fraction, molecular sieve surface treatment agent A is 30 parts, organic acid A is 17 parts, and molecular sieve A is 53 parts. Under a nitrogen atmosphere, the mixture is heated to 131°C for 45 minutes to obtain modified molecular sieve A. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve A is 90%, and the mass fraction of binder in extrusion aid is 10%. The mixture is extruded into strips and dried at 110°C for 110 minutes to obtain denitrifying agent A.

[0108] Preparation method of denitrification adsorbent B: The molecular sieve B is ITQ-37 molecular sieve, and the amount of medium strong acid accounts for 24% of the total acid content of the molecular sieve; the pore structure distribution is that the pore volume of mesopores and macropores (>2nm) accounts for 65% of the total pore volume.

[0109] Modifier B composition: Molecular sieve surface treatment agent B is trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl) acetate, trichloroethylsilane, methyldiphenylhydroxyethylsilane, and methyltrichlorosilane, with a mass fraction ratio of 3:2:7:1; Organic acid B is 3-aminoisonicotinic acid, diethylmalonic acid, 3-ethylisonicotinic acid, dithiodicarboxylic acid, and dimercaptosuccinic acid, with a mass fraction ratio of 4:0.9:1.5:2:2.6.

[0110] Molecular sieve B and modifier B are mixed, wherein, by mass fraction, molecular sieve surface treatment agent B is 5 parts, organic acid B is 16 parts, and molecular sieve B is 79 parts. Under a nitrogen atmosphere, the mixture is heated to 202℃ for 137 minutes to obtain modified molecular sieve B. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve B is 90%, and the mass fraction of binder and extrusion aid is 10%. The mixture is extruded and then dried at 100℃ for 90 minutes to obtain denitrifying agent B.

[0111] Adopting such Figure 1 The process shown employs a single-stage tandem hydrocracking process. Adsorption denitrification is carried out via a feed pipeline, with denitrifying agent A and denitrifying agent B being loaded sequentially along the feed direction. The properties of the feedstock are shown in Table 1. The reaction conditions and results are shown in Table 2.

[0112] Example 4

[0113] Preparation method of denitrification adsorbent A: ZSM-48 molecular sieve is selected for molecular sieve A, and the amount of medium strong acid accounts for 61% of the total acid content of the molecular sieve; the micropores (<2nm) account for 78% of the total pore volume in the pore structure distribution.

[0114] Modifier A composition: Molecular sieve surface treatment agent A is trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, and methyldiphenylhydroxyethylsilane, with a mass fraction ratio of 2:3.7:1:5.5:2.6; Organic acid A is 3-ethylisonicotinic acid, 3-aminoisonicotinic acid, 2-methoxy-3-methylisonicotinic acid, and 3,5-dichloroisonicotinic acid, with a mass fraction ratio of 1.4:1.7:2.7:4.9.

[0115] Molecular sieve A and modifier A are mixed, wherein, by mass fraction, molecular sieve surface treatment agent A is 19 parts, organic acid A is 10 parts, and molecular sieve A is 71 parts. Under a nitrogen atmosphere, the mixture is heated to 106°C for 364 min to obtain modified molecular sieve A. Then, binder microporous alumina and extrusion aid guar powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve A is 91%, and the mass fraction of binder and extrusion aid is 9%. The mixture is extruded and then dried at 105°C for 250 min to obtain denitrifying agent A.

[0116] Preparation method of denitrification adsorbent B: Molecular sieve B is X molecular sieve, with medium strong acid accounting for 37% of the total acid content of the molecular sieve; the pore structure distribution is such that mesopores and macropores (>2nm) account for 69% of the total pore volume.

[0117] Modifier B composition: Molecular sieve surface treatment agent B is trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl) acetate, trichloroethylsilane, trimethylethoxysilane, methyltrichlorosilane, and vinyltriacetoxysilane in a mass fraction ratio of 2.1:1.6:5:4.3:1; Organic acid B is 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, dithiodicarboxylic acid, and dimercaptosuccinic acid in a mass fraction ratio of 2.9:1.8:1:4.

[0118] Molecular sieve B and modifier B are mixed, wherein, by mass fraction, molecular sieve surface treatment agent B is 16 parts, organic acid B is 22 parts, and molecular sieve B is 62 parts. Under a nitrogen atmosphere, the mixture is heated to 201℃ for 178 minutes to obtain modified molecular sieve B. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve B is 88%, and the mass fraction of binder and extrusion aid is 12%. The mixture is extruded and then dried at 100℃ for 420 minutes to obtain denitrifying agent B.

[0119] Adopting such Figure 1The process shown employs a single-stage tandem hydrocracking process. Adsorption denitrification is carried out via a feed pipeline, with denitrifying agent A and denitrifying agent B being loaded sequentially along the feed direction. The properties of the feedstock are shown in Table 1. The reaction conditions and results are shown in Table 2.

[0120] Example 5

[0121] Preparation method of denitrification adsorbent A: Molecular sieve A is selected as 5A molecular sieve, and the amount of medium strong acid accounts for 68% of the total acid content of molecular sieve; in the pore structure distribution, the micropores (<2nm) account for 74% of the total pore volume.

[0122] Modifier A composition: Molecular sieve surface treatment agent A is trimethylchlorosilane, vinyltrichlorosilane, and methyldiphenylhydroxyethylsilane, with a mass fraction ratio of 4:2:1; Organic acid A is 3-ethylisonicotinic acid, 2,5-dichloroisonicotinic acid, and 2-methoxy-3-methylisonicotinic acid, with a mass fraction ratio of 1:1:1.

[0123] Molecular sieve A and modifier A are mixed, wherein, by mass fraction, molecular sieve surface treatment agent A is 8 parts, organic acid A is 17 parts, and molecular sieve A is 75 parts. The mixture is heated to 185℃ under a nitrogen atmosphere for 340 minutes to obtain modified molecular sieve A. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve A is 91%, and the binder and extrusion aid account for 9% by mass. The mixture is then extruded into strips. After molding, it is dried at 115℃ for 480 minutes to obtain denitrifying agent A.

[0124] Preparation method of denitrification adsorbent B: Molecular sieve B is selected as type X molecular sieve, and the amount of medium strong acid accounts for 36% of the total acid content of molecular sieve; the pore structure distribution is such that mesopores and macropores (>2nm) account for 68% of the total pore volume.

[0125] Modifier B composition: Molecular sieve surface treatment agent B is methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl) acetate, with a mass fraction ratio of 3:2:0.5; Organic acid B is 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, and m-nitrodicarboxylic acid, with a mass fraction ratio of 2:1:1.

[0126] Molecular sieve B and modifier B are mixed, wherein, by mass percentage, molecular sieve surface treatment agent B is 8 parts, organic acid B is 20 parts, and molecular sieve B is 72 parts. The mixture is heated to 182℃ under a nitrogen atmosphere for 324 minutes to obtain modified molecular sieve B. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve B is 89%, and the binder and extrusion aid account for 11% by mass. The mixture is then extruded into strips. After extrusion, the strips are dried at 113℃ for 360 minutes to obtain denitrifying agent B.

[0127] Adopting such Figure 1 The process shown employs a single-stage tandem hydrocracking process. Adsorption denitrification is carried out via a feed pipeline, with denitrifying agent A and denitrifying agent B being loaded sequentially along the feed direction. The properties of the feedstock are shown in Table 1. The reaction conditions and results are shown in Table 2.

[0128] Comparative Example 1

[0129] Compared to Example 4, only one denitrification adsorbent A was used, that is, an equal amount of denitrification adsorbent A was used to replace denitrification adsorbent B. The reaction conditions and reaction results are shown in Table 3.

[0130] The denitrification adsorbent A is prepared by using ZSM-48 molecular sieve A, with medium-strong acid accounting for 61% of the total acid content of the molecular sieve; and micropores (<2nm) accounting for 78% of the total pore volume in the pore structure distribution.

[0131] Modifier A composition: Molecular sieve surface treatment agent A is trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, and methyldiphenylhydroxyethylsilane, with a mass fraction ratio of 2:3.7:1:5.5:2.6; Organic acid A is 3-ethylisonicotinic acid, 3-aminoisonicotinic acid, 2-methoxy-3-methylisonicotinic acid, and 3,5-dichloroisonicotinic acid, with a mass fraction ratio of 1.4:1.7:2.7:4.9.

[0132] Molecular sieve A and modifier A are mixed, wherein, by mass fraction, molecular sieve surface treatment agent A is 19 parts, organic acid A is 10 parts, and molecular sieve A is 71 parts. Under a nitrogen atmosphere, the mixture is heated to 106°C for 364 min to obtain modified molecular sieve A. Then, binder microporous alumina and extrusion aid guar powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve A is 91%, and the mass fraction of binder and extrusion aid is 9%. The mixture is extruded and then dried at 105°C for 250 min to obtain denitrifying agent A.

[0133] Comparative Example 2

[0134] Compared to Example 2, only one denitrification adsorbent B was used, that is, an equal amount of denitrification adsorbent B was used to replace denitrification adsorbent A. The reaction conditions and reaction results are shown in Table 3.

[0135] The denitrification adsorbent B is prepared by selecting Beta molecular sieve, with medium-strong acid accounting for 37% of the total acid content of the molecular sieve; the pore structure distribution is such that mesopores and macropores (>2nm) account for 32% of the total pore volume.

[0136] Modifier B composition: Molecular sieve surface treatment agent B is trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl) acetate, vinyltriacetoxysilane, and methyltrichlorosilane, with a mass fraction ratio of 4:1:2; Organic acid B is 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, and 3-ethylisonicotinic acid, with a mass fraction ratio of 1:1.5:3.

[0137] Molecular sieve B and modifier B are mixed, wherein, by mass fraction, molecular sieve surface treatment agent B is 25 parts, organic acid B is 15 parts, and molecular sieve B is 60 parts. Under a nitrogen atmosphere, the mixture is heated to 138°C for 390 minutes to obtain modified molecular sieve B. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve B is 90%, and the binder and extrusion aid account for 10% of the mass fraction of modified molecular sieve B. The mixture is extruded and then dried at 100°C for 300 minutes to obtain denitrifying agent B.

[0138] Comparative Example 3

[0139] Compared with Example 3, an equal amount of denitrifying adsorbent DA was used to replace denitrifying adsorbent A. The reaction conditions and results are shown in Table 3.

[0140] Preparation method of denitrification adsorbent DA: ZSM-22 molecular sieve is selected for molecular sieve A, and the amount of medium strong acid accounts for 50% of the total acid content of molecular sieve; the pore volume of micropores (<2nm) in the pore structure distribution accounts for 50% of the total pore volume.

[0141] Molecular sieve A is mixed with binder microporous alumina and extrusion aid guar gum powder and extruded into strips. The molecular sieve A has a mass fraction of 90%, and the binder and extrusion aid have a mass fraction of 10%. After molding, the strips are dried at 110℃ for 110 min to obtain denitrification adsorbent DA.

[0142] Comparative Example 4

[0143] Compared with Example 3, an equal amount of denitrifying adsorbent DB was used to replace denitrifying adsorbent B. The reaction conditions and results are shown in Table 3.

[0144] Preparation method of denitrification adsorbent DB: The molecular sieve B is ITQ-37 molecular sieve, and the amount of medium strong acid accounts for 24% of the total acid content of the molecular sieve; the pore structure distribution is that the pore volume of mesopores and macropores (>2nm) accounts for 65% of the total pore volume.

[0145] Modifier B consists of: molecular sieve surface treatment agent B is octadecyltrimethylammonium bromide; organic acid B is benzenesulfonic acid, chlorosulfonic acid, and perchloric acid, with a mass fraction ratio of 2:5:1.

[0146] Molecular sieve B and modifier B are mixed, wherein, by mass fraction, molecular sieve surface treatment agent B is 5 parts, organic acid B is 16 parts, and molecular sieve B is 79 parts. Under a nitrogen atmosphere, the mixture is heated to 202℃ for 137 minutes to obtain modified molecular sieve B. Then, binder microporous alumina and extrusion aid guar gum powder are added and mixed evenly, wherein the mass fraction of modified molecular sieve B is 90%, and the mass fraction of binder and extrusion aid is 10%. The mixture is extruded and then dried at 100℃ for 90 minutes to obtain denitrifying agent B.

[0147] Comparative Example 5

[0148] Compared to Example 1, this comparative example uses a conventional single-stage tandem hydrocracking process without a denitrification adsorbent. The hydrorefined product obtained from the hydrorefining reactor outlet directly enters the hydrocracking reactor for hydrocracking. The properties of the feedstock are shown in Table 1. The reaction conditions and results are shown in Table 3.

[0149] Comparative Example 6

[0150] Compared to Example 1, this comparative example uses a conventional single-stage series hydrocracking process without a denitrification adsorbent. The hydrorefined product obtained from the hydrorefining reactor outlet directly enters the hydrocracking reactor for hydrocracking. The overall depth of the hydrorefining reaction is improved by reducing the volume hourly space velocity (VHSV) of the hydrorefining reactor, increasing the hydrorefining reaction temperature, and increasing the hydrorefining reactor pressure. The properties of the feedstock are shown in Table 1. The reaction conditions and results are shown in Table 3.

[0151] Table 1 Properties of Crude Oil

[0152]

[0153]

[0154] Table 2. Reaction conditions and results for each embodiment.

[0155]

[0156]

[0157] Table 3. Reaction conditions and results for each comparative example.

[0158]

[0159]

[0160] Table 4. Product yield and main properties of each example

[0161] Example 1 Example 2 Example 3 Example 4 Example 5 Yield, wt% gas 1.2 1.6 1.3 1.7 1.2 Light naphtha 4.5 5.3 4.1 5.9 4.8 Heavy naphtha 31.5 30.5 30.8 31.2 31.4 jet fuel 16.3 16.7 17.2 16.5 16.4 diesel fuel 25.1 24.9 24.3 23.8 25.0 tail oil 21.4 21.0 22.3 20.9 21.2 Main product properties Heavy naphtha aromatic potential, wt% 57 49 47 51 52 Aviation fuel smoke point, mm 31 28 25 26 28 Diesel cetane index 61 54 50 52 56

[0162] Table 5. Yields and main properties of each comparative product

[0163]

[0164]

[0165] Through the reaction effects of the examples and comparative examples, it can be found that the adsorption and denitrification agent with graded configuration using the method of the present invention can effectively adsorb ammonia and organic nitrogen compounds, thereby effectively reducing the severity of the hydrocracking reaction, which is conducive to the high activity performance of the hydrocracking catalyst. At the same time, the deactivation rate is greatly reduced, which is conducive to the long-term stable operation of the hydrocracking unit in processing inferior oil products.

Claims

1. An adsorption denitrification agent, characterized in that: The adsorption denitrification agent includes a molecular sieve and a modifier; the modifier includes a molecular sieve surface treatment agent and an organic acid.

2. The denitrifying agent according to claim 1, characterized in that, The adsorption denitrification agent is adsorption denitrification agent A; adsorption denitrification agent A includes molecular sieve A and modifier A, wherein the molecular sieve A is selected from at least one of ZSM series molecular sieves (preferably selected from at least one of ZSM-5, ZSM-22, and ZSM-48), mordenite, and 5A molecular sieve; Preferably, in the molecular sieve A, the amount of medium-strong acid accounts for more than 20% of the total acid amount of the molecular sieve, preferably 50% to 70%; in the pore structure distribution, the pore volume occupied by micropores with a pore size <2nm accounts for more than 10% of the total pore volume, preferably 50% to 80%. The modifier A comprises molecular sieve surface treatment agent A and organic acid A; the molecular sieve surface treatment agent A is selected from one or more of trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, and methyldiphenylhydroxyethylsilane, preferably one or more of trimethylchlorosilane, vinyltrichlorosilane, and methyldiphenylhydroxyethylsilane; the organic acid A is selected from one or more of 2,5-dichloroisonicotinic acid, 3,5-dichloroisonicotinic acid, 2-methoxy-3-methylisonicotinic acid, 3-ethylisonicotinic acid, and 3-aminoisonicotinic acid, preferably one or more of 3-ethylisonicotinic acid, 2,5-dichloroisonicotinic acid, and 2-methoxy-3-methylisonicotinic acid.

3. The denitrifying agent according to claim 2, characterized in that, In the denitrifying agent A, by mass parts, Molecular sieve A: 50–95 parts; Molecular sieve surface treatment agent A: 5-30 parts; Organic acid A: 7-50 parts; Preferably, in the denitrifying agent A, by mass parts, Molecular sieve A: 60-80 parts; Molecular sieve surface treatment agent A: 8-20 parts; 3-Ethylisonicotinic acid: 3-20 parts, preferably 5-15 parts; 2,5-Dichloroisonicotinic acid: 2-15 parts, preferably 5-10 parts; 2-Methoxy-3-methylisonicotinic acid: 2-15 parts, preferably 5-10 parts.

4. The denitrifying agent according to claim 2 or 3, characterized in that, The preparation method of denitrifying agent A includes: mixing molecular sieve A with modifier A, heating to 75-210°C, preferably 120-190°C, under an inert atmosphere for 30-480 min, preferably 120-400 min, to obtain modified molecular sieve A, then molding and drying the modified molecular sieve A to obtain denitrifying agent A.

5. The denitrifying agent according to claim 1, characterized in that, The adsorption denitrification agent is adsorption denitrification agent B; the adsorption denitrification agent B includes molecular sieve B and modifier B, wherein the molecular sieve B is selected from at least one of Y-type molecular sieve, X-type molecular sieve, Beta molecular sieve, and ITQ series molecular sieve; Preferably, in the molecular sieve B, the amount of medium-strong acid accounts for less than 50% of the total acid amount of the molecular sieve, more preferably 20% to 40%; in the pore structure distribution, the pore volume of mesopores and macropores with a pore size > 2 nm accounts for more than 20% of the total pore volume, more preferably 30% to 70%. The modifier B comprises a molecular sieve surface treatment agent B and an organic acid B; the molecular sieve surface treatment agent B is selected from one or more of trimethylchlorosilane, vinyltrichlorosilane, vinyltriacetoxysilane, trimethylethoxysilane, methyldiphenylhydroxyethylsilane, methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2(fluorosulfonyl) acetate, preferably one or more of methyltrichlorosilane, trichloroethylsilane, and trimethylsilyl 2,2-difluoro-2(fluorosulfonyl) acetate; the organic acid B is selected from one or more of 3,4-thiophene dicarboxylic acid, dithiodicarboxylic acid, m-nitrodicarboxylic acid, diethylmalonic acid, dimercaptosuccinic acid, 3-aminoisonicotinic acid, and 3-ethylisonicotinic acid, preferably one or more of 3-aminoisonicotinic acid, 3,4-thiophene dicarboxylic acid, and m-nitrodicarboxylic acid.

6. The denitrifying agent according to claim 5, characterized in that, In the adsorption and denitrification agent B, by mass parts, Molecular sieve B: 50–95 parts; Molecular sieve surface treatment agent B: 5-30 parts; Organic acid B: 14–65 parts; Preferably, in the adsorption denitrification agent B, by mass parts, Molecular sieve B: 60-80 parts; Molecular sieve surface treatment agent B: 8-20 parts; 3-Aminoisonicotinic acid: 10-20 parts; 3,4-Thiophene dicarboxylic acid: 5–15 parts; m-Nitrodicarboxylic acid: 5-10 parts.

7. The method according to claim 5 or 6, characterized in that, The preparation method of adsorption denitrification agent B includes: mixing molecular sieve B with modifier B, heating to 75-210°C, preferably 120-190°C, under an inert atmosphere for 30-480 min, preferably 120-360 min, to obtain modified molecular sieve B, then molding and drying the modified molecular sieve B to obtain denitrification agent B.

8. A method for improving the operational stability of a hydrocracking unit, comprising a single-stage series hydrocracking process, the method comprising: The feedstock oil and hydrogen are sequentially subjected to hydrorefining, adsorption denitrification and hydrocracking to obtain hydrocracking products; wherein, the mass content of organic nitrogen-containing compounds in the hydrorefining products is more than 10 ppm, preferably more than 15 ppm, and the mass content of ammonia is more than 500 ppm, preferably more than 800 ppm; the adsorption denitrification uses the adsorption denitrification agent described in claim 1.

9. The method according to claim 8, characterized in that, The adsorption denitrification is carried out using a container filled with an adsorbent, or a separately installed adsorption reactor, or a logistics pipeline filled with an adsorbent, preferably a logistics pipeline filled with an adsorbent.

10. The method according to claim 8, characterized in that, The mass content of organic nitrogen-containing compounds in the hydrogenation refining product is 10ppm to 200ppm, preferably 15ppm to 120ppm, and the mass content of ammonia is 500ppm to 5000ppm, preferably 800ppm to 3800ppm.

11. The method according to claim 8, characterized in that, The adsorption denitrification agent used in the adsorption denitrification includes adsorption denitrification agent A as described in any one of claims 2-4 and adsorption denitrification agent B as described in any one of claims 5-7. The hydrorefined product is first contacted with adsorption denitrification agent A, and then with adsorption denitrification agent B.

12. The method according to claim 11, characterized in that, The volume ratio of adsorbent A to adsorbent B is 0.5:1 to 5:1, preferably 0.8:1 to 3:

1.

13. The method according to claim 9, characterized in that, In the logistics pipeline, the total filling volume of adsorbent A and adsorbent B accounts for 5%-90% of the effective logistics pipeline volume, preferably 10%-60%.

14. The method according to claim 8, characterized in that, The operating conditions for adsorption denitrification are as follows: adsorption temperature 100–450℃, preferably 300–370℃; pressure 3.0–20.0 MPa, preferably 10–18 MPa; and volume hourly space velocity (VHSV) 0.1–20 h⁻¹. -1 Preferably 0.5 to 15 hours -1 .

15. The method according to claim 8, characterized in that, The feedstock oil is at least one of vacuum gas oil, coking gas oil, fluidized bed gas oil, deasphalted oil, and slurry bed gas oil; the nitrogen content of the feedstock oil is greater than 300 ppm, preferably 1200-4000 ppm.

16. The method according to claim 8, characterized in that, The operating conditions for hydrorefining are as follows: reaction temperature 300℃~420℃, preferably 310℃~390℃; reactor inlet pressure 6MPa~20MPa, preferably 8MPa~19MPa; volume hourly space velocity (VHSV) 0.3h⁻¹. -1 ~3.0h -1 0.4h is preferred -1 ~2.5h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–1200, preferably 500–1100. And / or, the operating conditions for hydrocracking are as follows: reaction temperature of 350℃~435℃, preferably 360℃~430℃; reactor inlet pressure of 6MPa~20MPa, preferably 8MPa~19MPa; and volume hourly space velocity of 0.5h⁻¹. -1 ~5.0h -1 0.6h is preferred -1 ~3.0h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–1200, preferably 500–1100.

17. The method according to claim 8, characterized in that, The adsorption denitrification is operated in a way that allows multiple sets to be connected in parallel and switchable.

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