Method for producing BTX from rich-aroma light cracked distillate oil

Abstract

This invention provides a method for producing BTX from rich aromatic light cracked distillate oil. The method employs a three-stage circulating hydrogenation process: the first stage is selective hydrogenation of dienes; the second stage is selective hydrogenation of polycyclic aromatic hydrocarbons; and the third stage is selective hydrocracking. For rich aromatic light cracked distillate oil with a final boiling point of 220–280°C and a total aromatic content greater than 90%, the total liquid phase product yield is greater than 80%, of which the liquid phase product BTX yield is greater than 50%.

Description

Technical Field

[0001] This invention relates to the field of hydrotreating rich aromatic distillate oils, and more specifically to a method for producing BTX from rich aromatic light cracked distillate oils. Background Technology

[0002] Aromatic cracked distillate is a product of high-temperature condensation of feedstock and products during the steam cracking process of ethylene cracking. It mainly comes from the bottom of the quench oil tower and the bottom of the heavy fuel oil stripping tower. Aromatic cracked distillate is a heavy distillate oil (>205℃) rich in aromatics (aromatic content greater than 90%). Its main components are monocyclic and polycyclic aromatic compounds with short side chains, high carbon-hydrogen ratio, and low content of heavy metals and ash. The oil also contains heterocyclic compounds of elements such as N, S, and O.

[0003] The yield of rich aromatic cracked distillate oil is relatively high in the 170℃–300℃ range, followed by very heavy gum and asphaltenes. It also has high sulfur content, high polycyclic aromatic hydrocarbon (PAH) content, and high density. The main components of the initial boiling point to 205℃ range are indene and its homologues; the 205–225℃ range contains naphthalene; the 225–245℃ range is mainly methylnaphthalene; the 245–300℃ range is mainly dimethylnaphthalene; the 300–360℃ range contains large amounts of anthracene, acenaphthene, and phenanthrene; and the substances above 360℃ are mainly gums and asphaltenes with a high C-H ratio. Naphthalene-based and higher PAHs account for more than 60% of the total composition.

[0004] Rich-aromatic cracked distillate oil is mainly used as a raw material for the production of carbon black. Several companies have also begun to use cracked fuel oil to produce aromatic solvent oils, with major manufacturers including ExxonMobil (USA), Shell (Netherlands), and Maruzen Oil Company (Japan).

[0005] Cracked C9 fraction is also a type of aromatic cracked distillate oil, mainly derived from the cracked gasoline C9 fraction separated after passing through the BTX tower. Its aromatic content is as high as 70% or more (more than 90% after extracting dicyclopentadiene), accounting for 11% to 22% of ethylene production.

[0006] How to utilize these low-value-added aromatic-rich cracked distillates is a problem that petrochemical scientists urgently need to solve. Benzene (B), toluene (T), and xylene (X) are important basic organic chemical raw materials, widely used in the production of polyester, chemical fibers, and other products. They are closely related to national economic development and people's basic needs, and demand has been strong and rapidly increasing in recent years. Considering the abundant aromatic resources in ethylene tar and cracked C9, how to convert low-value-added aromatic-rich cracked distillates into BTX through catalytic conversion technology presents both a huge opportunity and a significant challenge.

[0007] In the field of hydrotreating rich aromatic distillate fuels, catalytic cracking feedstock hydrotreating technology has been industrially applied since the 1970s, and has been used in many refineries processing sulfur-containing or high-sulfur crude oils. Currently, mature catalytic cracking feedstock pretreatment technologies include: UOP's VGO Unionfining and APCU (partial conversion hydrocracking) technologies, and Haldor's... The company's Aroshift technology, Chevron's VGO Hydrotreating technology, Exxon's VGO Hydrodesulfurization technology, IFP's T-star technology, and Mobil, AKZO, and Kellogg's MAKfinging technology, among others, are all being utilized. To further improve product quality and conversion rates, catalytic feedstock hydrotreating pretreatment processes are gradually shifting from traditional hydrodesulfurization (HDS) to moderate hydrocracking (MHC) to enhance denitrification, residual carbon, and polycyclic aromatic hydrocarbon saturation capabilities.

[0008] In summary, existing technologies generally employ hydrogenation saturation and hydrocracking processes, which not only result in high hydrogen consumption for aromatic-rich cracked distillate oils with an aromatic content greater than 90%, but also waste valuable aromatic resources. Summary of the Invention

[0009] To address the problem of low BTX yield in the high-value chemical utilization of rich aromatic light cracked distillate oil in existing technologies, this invention provides a new method for producing BTX from rich aromatic light cracked distillate oil, which significantly improves the BTX yield.

[0010] The first aspect of this invention provides a method for producing BTX from rich aromatic light cracked distillate oil. This method employs a three-stage hydrogenation process: the first stage hydrogenation is selective hydrogenation of dienes, the second stage hydrogenation is selective hydrogenation of polycyclic aromatic hydrocarbons, and the third stage hydrogenation is selective hydrocracking.

[0011] The catalyst used in the third-stage hydrogenation (i.e., the third-stage hydrogenation catalyst) comprises the following components by weight percentage:

[0012] a)5%~20%Ni;

[0013] b) 0.01%–5.00% CeO2;

[0014] c) 55.00%~89.99% ZSM-5;

[0015] d) 5%–20% adhesive;

[0016] The catalyst used in the third stage of hydrogenation has a TPR hydrogen atmosphere reduction temperature of less than 420°C and a dispersion of Ni of the active component greater than 7.5%, preferably 9% to 20%.

[0017] Further, preferably, the catalyst used in the third stage of hydrogenation has, by weight percentage, a Ni content of 10% to 15%, a CeO2 content of 0.5% to 3.0%, a binder content of 8% to 15%, and the balance being ZSM-5.

[0018] Furthermore, alkaline earth metals such as calcium can be added to the catalyst used in the third-stage hydrogenation as an anti-coking agent. Preferably, the catalyst used in the third-stage hydrogenation contains 0.1% to 3.0% alkaline earth metal oxides, and more preferably, the alkaline earth metal oxides are calcium oxide and / or magnesium oxide.

[0019] Further, preferably, the TPR hydrogen atmosphere reduction temperature of the catalyst used in the third stage hydrogenation is below 400°C, more preferably, the TPR hydrogen atmosphere reduction temperature of the catalyst used in the third stage hydrogenation is below 390°C, and the dispersion of the active component Ni is greater than 10%, preferably 11% to 20%.

[0020] Furthermore, the catalyst used in the first stage of hydrogenation (i.e., the first stage hydrogenation catalyst) is a Ni-based catalyst with a nickel content of 12% to 16% based on the catalyst weight.

[0021] Furthermore, the catalyst used in the second stage of hydrogenation (i.e., the second stage hydrogenation catalyst) includes a TiO2-SiO2-Al2O3 composite support and an active component Mo-Ni. Based on the weight of the catalyst, the content of the composite support is 64% to 90%, the content of the active component Mo (calculated as MoO3) is 8% to 30%, the content of the active component Ni (calculated as NiO) is 2% to 6%, and based on the total weight of the Al2O3-TiO2-SiO2 composite support, the content of Al2O3 is 80% to 98%, the content of TiO2 is 1% to 10%, and the content of SiO2 is 1% to 15%.

[0022] Furthermore, the three-stage hydrogenation process includes: the rich aromatic light cracked distillate oil and hydrogen undergo a diene selective hydrogenation reaction in the presence of a first-stage hydrogenation catalyst; the product obtained from the first-stage hydrogenation undergoes a polycyclic aromatic hydrocarbon selective hydrogenation reaction in the presence of a second-stage hydrogenation catalyst; the product obtained from the second-stage hydrogenation undergoes a selective hydrocracking reaction in the presence of a third-stage hydrogenation catalyst; and the hydrocracking product obtained from the third-stage hydrogenation is separated to obtain BTX.

[0023] Further, the first stage of hydrogenation involves hydrogenating dienes, styrene, etc., in the aromatic light cracked distillate to monoolefins, with a bromine value of less than 25gBr2 / 100g oil. The second stage of hydrogenation involves removing unsaturated hydrocarbons, sulfur, and nitrogen from the aromatics in the first stage hydrogenation product, and selectively hydrogenating polycyclic aromatic hydrocarbons to tetrahydronaphthalene compounds, with a polycyclic aromatic hydrocarbon content of less than 2% and an aromatic hydrocarbon retention rate of greater than 93%. The third stage of hydrogenation involves selectively hydrocracking the tetrahydronaphthalene compounds in the second stage hydrogenation product, and selectively ring-opening and dealkylating polycyclic aromatic hydrocarbons to generate BTX, with a total liquid phase product yield of greater than 80% in the hydrocracking products, of which the liquid phase product BTX yield is greater than 50%.

[0024] Furthermore, the three-stage hydrogenation is preferably carried out in a three-stage cyclic hydrogenation manner, wherein the circulating material for the first stage hydrogenation is the product obtained from the first stage hydrogenation, the circulating material for the second stage hydrogenation is the product obtained from the second stage hydrogenation, and the circulating material for the third stage hydrogenation is the hydrocracking product obtained from the third stage hydrogenation.

[0025] Furthermore, the reaction conditions for the first stage of hydrogenation are: reactor inlet temperature 40–90°C, and fresh feed space velocity 0.8–2.0 h⁻¹. -1 The circulation ratio is 1.0:2.0 to 1.0:7.0, the hydrogen-to-oil volume ratio is 300 to 1000, and the pressure is 2 to 8 MPa.

[0026] Furthermore, the reaction conditions for the second stage of hydrogenation are: reactor inlet temperature 240–350°C, and fresh feed space velocity 0.8–2.0 h⁻¹. -1 The circulation ratio is 1.0:0.3 to 1.0:2.0, the hydrogen-to-oil volume ratio is 500 to 2000, and the pressure is 2 to 8 MPa.

[0027] Furthermore, the reaction conditions for the third-stage hydrogenation are: reactor inlet temperature 380–480°C, and fresh feed space velocity 0.6–4.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500–2000, and the pressure is 2–8 MPa.

[0028] Furthermore, the feedstock for the second stage hydrogenation reaction is the product obtained from the first stage hydrogenation reaction, and the feedstock for the third stage hydrogenation reaction is the product obtained from the second stage hydrogenation reaction.

[0029] Furthermore, the rich aromatic light cracked distillate oil has an initial boiling point of 85–170°C and a final boiling point of 220–280°C. The feedstock composition is: sulfur content <600 ug / mL, nitrogen content <300 ug / mL, and aromatic content >90 wt%.

[0030] The present invention also provides a method for preparing the catalyst used in the second stage of hydrogenation, comprising:

[0031] The TiO2-SiO2-Al2O3 composite support was impregnated with a Mo-Ni impregnation solution, dried, and calcined to obtain the catalyst used for the second stage of hydrogenation.

[0032] Furthermore, the composite carrier is a commercially available Al2O3-TiO2-SiO2 carrier, with the TiO2 content being 1% to 10% and the SiO2 content being 1% to 15% based on the weight of the composite carrier, and the remainder being Al2O3.

[0033] Furthermore, the composite carrier undergoes activation treatment before use, with activation conditions being: calcination at 400–700°C for 1–8 hours.

[0034] Furthermore, the saturated water absorption rate of the composite carrier is 90-110%.

[0035] Furthermore, the impregnation solution contains 2-15 g of NiO and 10-30 g of Mo2O3.

[0036] Furthermore, the impregnation method is not particularly limited and can be impregnated according to conventional impregnation methods in the art.

[0037] Furthermore, the drying conditions are: a drying temperature of 50–200°C and a drying time of 2–48 hours.

[0038] Furthermore, the calcination conditions are as follows: calcination temperature is 300–600℃, and calcination time is 2–24h.

[0039] The present invention also provides a method for preparing the catalyst used in the third stage hydrogenation, comprising:

[0040] The composite carrier containing CeO2 and ZSM-5 is contacted with an impregnation solution containing a nickel source, a chelating surfactant and an alkanolamine for aging impregnation, followed by a first drying, a first calcination and reduction.

[0041] Furthermore, the composite carrier containing CeO2 and ZSM-5 contains alkaline earth metal oxides, and the specific amount used is selected according to needs.

[0042] Furthermore, the range of nickel source types is relatively wide. Preferably, the nickel source is selected from at least one of nickel nitrate, nickel acetate, and basic nickel carbonate.

[0043] Furthermore, the range of chelating surfactants is relatively wide. Preferably, the chelating surfactant is an alkyl ethylenediamine triacetic acid surfactant; more preferably, the alkyl ethylenediamine triacetic acid surfactant is selected from one or more of sodium N-dodecyl ethylenediamine triacetate, sodium N-hexadecyl ethylenediamine triacetate, and sodium N-octadecyl ethylenediamine triacetate.

[0044] Furthermore, the range of alkanolamines that can be selected is relatively wide. Preferably, the alkanolamine is one or more of triethanolamine, diethanolamine, and ethanolamine.

[0045] Furthermore, based on the weight of Ni in the impregnation solution, the amount of chelating surfactant in the impregnation solution is 0.02% to 35% of the amount of Ni, preferably 0.06% to 35%, and the amount of alkanolamine is 0.02% to 35% of the amount of Ni, preferably 0.06% to 35%.

[0046] Furthermore, there are no special requirements for the impregnation method; conventional impregnation methods and conditions can be used. Preferably, the composite carrier is impregnated using an equal-volume impregnation method or a spray method. The impregnation conditions include: equal-volume impregnation, an aging temperature of 10–80°C, preferably 15–30°C, and an aging time of 0.5–24 h.

[0047] Furthermore, commonly used drying conditions can be used in this invention. According to a preferred embodiment of this invention, the first drying conditions include: a temperature of 30 to 200°C and a time of 2 to 48 hours.

[0048] Furthermore, commonly used roasting conditions can be used in this invention. According to a preferred embodiment of this invention, the conditions for the first roasting include: a temperature of 300–600°C and a time of 0.5–24 h.

[0049] Furthermore, commonly used reduction conditions can all be used in this invention. According to a preferred embodiment of this invention, the reduction conditions include: a reduction temperature of 350–550°C and a time of 24–100 h.

[0050] Furthermore, the preparation method of the composite carrier containing CeO2 and ZSM-5 includes: mixing and contacting ZSM-5 powder, optionally an alkaline earth metal source, a cerium source, a binder source, optionally an additive source, and an acid solution, followed by kneading, molding, a second drying, and a second calcination.

[0051] Further, preferably, the preparation method of the composite carrier containing CeO2 and ZSM-5 includes: mixing an adhesive source, ZSM-5 powder and optional additives to obtain a first mixture, and then mixing and contacting the first mixture with an acid solution containing a cerium source and optional alkaline earth metal source to perform the kneading, molding, second drying, and second calcination; preferably, the weight ratio of the first mixture to the acid solution is 100:5 to 100:100.

[0052] Furthermore, the ZSM-5 powder is of the hydrogen form, and the SiO2 / Al2O3 molar ratio is 50-500, preferably 50-300, and more preferably 100-250.

[0053] Furthermore, the adhesive source is selected from at least one of silica sol, water glass, boehmite, silica, and alumina sol, preferably at least one of boehmite, water glass, and silica sol.

[0054] Furthermore, the source of the additive is selected from at least one of methylcellulose, fennel powder, polyethylene glycol, calcium nitrate, magnesium nitrate, and hydroxymethylcellulose.

[0055] Furthermore, the acidic substance in the acid solution is selected from at least one of nitric acid, phosphoric acid, acetic acid, citric acid, and tartaric acid.

[0056] Furthermore, the acid solution is an acidic aqueous solution with a concentration of 1-6% by weight. This improves the selective hydrogenation effect of hydrocracking.

[0057] Furthermore, the alkaline earth metal source has no special requirements. For example, it can be a commonly used alkaline earth metal compound. For instance, when the alkaline earth metal is calcium, it can be calcium nitrate. This is only an illustrative example and should not be construed as limiting the scope of the present invention.

[0058] Furthermore, there are no special requirements for the drying conditions. According to a preferred embodiment of the present invention, the second drying conditions include: drying at 50–200°C for 3–48 hours, preferably at 60–120°C for 5–12 hours. There are no special requirements for the calcination conditions. According to a preferred embodiment of the present invention, the second calcination conditions include: calcination at 450–750°C for 0.5–24 hours, preferably at 480–650°C for 1–24 hours.

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] The method for producing BTX from rich aromatic light cracked distillate provided by this invention employs a three-stage circulating hydrogenation process. The first stage of hydrogenation is selective hydrogenation of dienes, the second stage is selective hydrogenation of polycyclic aromatic hydrocarbons, and the third stage is selective hydrocracking. In the third stage, chelating surfactants, such as alkyl ethylenediamine triacetic acid surfactants and alkanolamine organic compounds, are added to the catalyst during the preparation process to lower the reduction temperature of the catalyst under hydrogen atmosphere in the TPR. At the same time, cerium oxide is added to the support to improve the BTX yield.

[0061] The method for producing BTX from rich aromatic light cracked distillate provided by this invention effectively solves the problem that rich aromatic light cracked distillate cannot be directly utilized, enabling the efficient conversion of low-value-added rich aromatic light cracked distillate into high-value-added BTX. For rich aromatic light cracked distillate with an initial boiling point of 85–170℃, a final boiling point of 220–280℃, and a total aromatic content greater than 90%, the yield of total liquid phase products is greater than 80%, and the yield of liquid phase product BTX is greater than 50%, achieving good technical results. Attached Figure Description

[0062] Figure 1 The process flow of the method for producing BTX from rich aromatic light cracked distillate oil of the present invention is as follows;

[0063] 1-First stage reactor; 2-Second stage reactor; 3-Third stage reactor; 4-Separator 1; 5-Separator 2; 6-Separator 3; 7-Benzene removal tower; 8-Toluene tower; 9-Xylene tower; 10-Rich aromatic light cracked distillate oil; 11-Solvent oil; 12-H2+CH4; 13-C2-C4 alkanes; 14-Benzene; 15-Toluene; 16-C8 aromatics; 17-Heavy material; 18-Residual liquid;

[0064] Figure 2 This is a distribution-online time graph of the material in Embodiment 1 of the present invention;

[0065] Figure 3 The XRD pattern of the catalyst used in the third stage of hydrogenation in Example 1 of this invention;

[0066] Figure 4 This is the temperature-programmed reduction (TPR) spectrum of the catalyst used in the third stage hydrogenation of Example 1 of the present invention;

[0067] Figure 5 This is a product distribution-online time graph for Comparative Example 1 of the present invention;

[0068] Figure 6 The TPR spectrum is shown for the catalyst used in the third stage hydrogenation of Comparative Example 1 of the present invention. Detailed Implementation

[0069] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0070] In this invention, the rich aromatic light cracked distillate oil (10) undergoes a first-stage reaction to remove dienes from the feedstock. Due to the large heat release of the reaction, partial recycling is adopted to reduce the reaction temperature rise. That is, part of the first-stage reaction product is refluxed back to the inlet of the first-stage reactor and mixed with the feedstock before entering the reactor (1) again; another part of the first-stage reaction product enters the second-stage reactor (2). Since the second-stage reaction mainly involves selective hydrogenation, desulfurization, and denitrification of polycyclic aromatic hydrocarbons, the heat release is large, requiring partial recycling to reduce the reaction temperature rise. That is, part of the second-stage reaction product is refluxed back to the inlet of the second-stage reactor and mixed with the second-stage feedstock before entering the second-stage reactor (2) again; another part of the second-stage reaction product enters the third-stage reactor (3); the third-stage reaction... The main reactions are hydrocracking, dealkylation, and alkyl transfer reactions. The reaction products are separated into liquid and gas phases by separator (4). The gas phase products are separated into H2+CH4 (12) by separator (5). The bottom of the tank is separated into C2-C4 (13) gas phase products and bottom liquid (18) by separator (6). The liquid phase products separated by separator (4) are separated into benzene by benzene stripping tower (7). The bottom of the tower enters toluene tower (8) to separate toluene. The bottom of the toluene tower enters xylene tower (9) to separate xylene. The bottom of the tower is recycled to the inlet of the third reactor and mixed with the raw materials of the third stage before entering the reactor (3). Some of the heavy material at the bottom of the xylene tower (17) is discharged outside the boundary to prevent the accumulation of heavy material inside the system.

[0071] In this invention, the dispersion of the active component Ni is tested by hydrogen-oxygen titration.

[0072]

[0073] In the formula: R-----the dispersion of Ni;

[0074] [Ni] ----- Number of nickel atoms on the surface;

[0075] [Ni] 总 -----Total number of nickel atoms;

[0076] V0-----Titration volume of hydrogen, mL;

[0077] N A -----Avogadro's constant (6.023) × 10 23 ;

[0078] W-----Sample mass, g;

[0079] P-----Mass fraction of nickel in the sample, %;

[0080] M ----- The atomic weight of nickel is 58.7.

[0081] In this invention, the test method for TPR hydrogen atmosphere reduction is hydrogen-oxygen titration.

[0082] In this invention, the method for calculating the yield of liquid-phase products is as follows:

[0083] Liquid phase product yield = W 液体产物 / W 原料 ,

[0084] W 液体产物 -----Weight of the liquid phase reaction products (in grams) after 24 hours of online processing;

[0085] W 原料 ----Feed amount of rich-aroma light cracked distillate oil feedstock, in grams, for 24 hours online.

[0086] In this invention, the reduction peak temperature of the active component Ni is determined using the TPR (temperature-programmed reduction) method. The reduction is carried out in a hydrogen atmosphere, with a heating rate of 10°C / minute, and the temperature is raised to 900°C.

[0087]

Example 1

[0088] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel. The reactor (reactor 1) inlet temperature is 45℃, the pressure is 6.0MPa, and the fresh feed space velocity is 1.0h. -1 The hydrogen-to-oil volume ratio was 500, and the fresh oil to recycled product volume ratio was 1.0:5.0. The reaction conditions and product data are shown in Table 1.

[0089] The second-stage hydrogenation uses a Ni-Mo / TiO2-SiO2-Al2O3 catalyst. The reactor (2 reactors) inlet temperature is 280℃, the pressure is 5.5MPa, and the fresh feed space velocity is 0.8h. -1 The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0090] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 420℃, a pressure of 5.0 MPa, and a fresh feed space velocity of 0.8 h⁻¹. -1With a hydrogen-to-oil volume ratio of 1500, the material from the outlet of the third reaction reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3, producing fuel gas, C2-C4 alkanes, and a small amount of residual liquid, respectively. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third reaction reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. Figure 2 The catalyst used in the three-stage hydrogenation process has the following composition: the active component Ni content is 15%, and the remainder is a composite support.

[0091] The catalyst used in the third stage of hydrogenation is prepared as follows:

[0092] 832 g of ZSM-5 molecular sieve powder with a hydrogen form SiO2 / Al2O3 ratio of 150 (dried before use) was selected and mixed evenly with 15 g each of pseudoboehmite (containing 150 g of alumina), methylcellulose, and guar gum powder. Then, 8 g of nitric acid and 5 g of citric acid were added to 600 g of water and dissolved evenly. Cerium nitrate (containing 8 g of cerium oxide) and calcium nitrate (containing 10 g of calcium oxide) were added and dissolved evenly. The solution was poured into the above mixed powder and kneaded for 35 minutes. The mixture was extruded into strips, placed at 20°C for 12 hours, dried at 110°C for 6 hours, and then calcined in a muffle furnace at 600°C for 5 hours to obtain the composite carrier (composite carrier weight percentage composition: ZSM-5 content 83.2%, Al2O3 content 15%, calcium oxide content 1%, cerium oxide content 0.8%), with a water absorption rate of 102%.

[0093] A soluble metal salt precursor was used to prepare an impregnation solution containing 30 g of Ni. The solution volume was controlled at 170 mL. 1 g of sodium N-dodecylethylenediaminetriacetate and 1 g of triethanolamine were added to the impregnation solution and stirred until homogeneous. 170 g of a composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method. The mixture was aged at 25 °C for 16 hours, dried at 100 °C for 4 hours, and calcined at 400 °C for 4 hours to obtain the oxidized catalyst. Reduction at 350 °C under a hydrogen atmosphere for 48 hours yielded the reduced catalyst. XRD patterns of the hydrogen-form ZSM-5 powder, the composite support, and the catalyst are shown below. Figure 3 The temperature-programmed reduction (TPR) spectra of the oxidizing catalyst are shown below. Figure 4 ,Depend on Figure 4 It can be seen that the peak reduction temperature of the active component under a hydrogen atmosphere is 377℃, indicating that the active component is well dispersed, easy to reduce, and has high activity. The dispersion of Ni in the reduced catalyst is 16.3%.

[0094]

Example 2

[0095] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel, the reactor (reactor 1) inlet temperature is 45℃, and the fresh feed space velocity is 1.0 h⁻¹. -1 The volume ratio of fresh oil to recycled product was 1.0:5.0, the hydrogen-to-oil volume ratio was 500, the pressure was 6.0 MPa, and the reaction conditions and product data are shown in Table 1.

[0096] The second-stage hydrogenation reactor (2 reactors) has an inlet temperature of 280℃, a pressure of 5.5MPa, and a fresh feed space velocity of 0.8h. -1 The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0097] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 450℃, a pressure of 6.5MPa, and a fresh feed space velocity of 1.2h / h. -1 The hydrogen-to-oil volume ratio is 800. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0098] The catalyst used in the third stage of hydrogenation is prepared as follows:

[0099] 840 grams of ZSM-5 molecular sieve powder with a hydrogen form SiO2 / Al2O3 ratio of 150 (dried before use) were selected and mixed evenly with silica sol containing 145 grams of silicon dioxide, 15 grams each of methylcellulose and Tianqing powder. Then, 8 grams of nitric acid and 5 grams of citric acid were added to 550 grams of water and dissolved evenly. Cerium nitrate containing 5 grams of cerium oxide and calcium nitrate containing 10 grams of calcium oxide were added and dissolved evenly. The solution was poured into the above mixed powder and kneaded for 35 minutes. The mixture was extruded into strips, placed at 20°C for 12 hours, dried at 110°C for 6 hours, and then calcined in a muffle furnace at 600°C for 4 hours to obtain the composite carrier (composite carrier weight percentage composition: ZSM-5 content 84%, SiO2 (binder) content 14.5%, calcium oxide content 1.0%, cerium oxide content 0.5%), with a water absorption rate of 103%.

[0100] A soluble metal salt precursor, basic nickel carbonate, was used to prepare an impregnation solution containing 30 g of Ni. The solution volume was controlled at 170 mL. 0.02 g of sodium N-hexadecylethylenediaminetriacetate and 8 g of ethanolamine were added to the impregnation solution and stirred until homogeneous. 170 g of composite support was used, and an equal volume of the impregnation solution was loaded onto the composite support using a rotary drum spray method. The mixture was aged at 25 °C for 16 hours, dried at 100 °C for 4 hours, and calcined at 400 °C for 4 hours to obtain the oxidizing catalyst. The reducing catalyst was obtained by reducing it at 400 °C under a hydrogen atmosphere for 42 hours. The Ni dispersion of the reducing catalyst was 15.8%, and the TPR (temperature programmed reduction) reduction peak temperature of the oxidizing catalyst was 380 °C.

[0101]

Example 3

[0102] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel, the reactor (reactor 1) inlet temperature is 45℃, and the fresh feed space velocity is 1.0 h⁻¹. -1 The volume ratio of fresh oil to recycled product was 1.0:5.0, the hydrogen-to-oil volume ratio was 500, the pressure was 6.0 MPa, and the reaction conditions and product data are shown in Table 1.

[0103] The second-stage hydrogenation reactor (2 reactors) has an inlet temperature of 280℃, a pressure of 5.5MPa, and a fresh feed space velocity of 0.8h. -1The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0104] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 410℃, a pressure of 5.5MPa, and a fresh feed space velocity of 1.0h. -1 The hydrogen-to-oil volume ratio is 1500. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0105] The catalyst used in the third stage of hydrogenation is prepared using the same method as in [Example 1].

[0106]

Example 4

[0107] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel, the reactor (reactor 1) inlet temperature is 45℃, and the fresh feed space velocity is 1.0 h⁻¹. -1 The volume ratio of fresh oil to recycled product was 1.0:5.0, the hydrogen-to-oil volume ratio was 500, the pressure was 6.0 MPa, and the reaction conditions and product data are shown in Table 1.

[0108] The second-stage hydrogenation reactor (2 reactors) has an inlet temperature of 280℃, a pressure of 5.5MPa, and a fresh feed space velocity of 0.8h. -1 The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0109] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 410℃, a pressure of 5.5MPa, and a fresh feed space velocity of 1.0h. -1 The hydrogen-to-oil volume ratio is 1800. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0110] The catalyst used in the third stage of hydrogenation is prepared using the same method as in [Example 1].

[0111]

Example 5

[0112] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel, the reactor (reactor 1) inlet temperature is 45℃, and the fresh feed space velocity is 1.0 h⁻¹. -1 The volume ratio of fresh oil to recycled product was 1.0:5.0, the hydrogen-to-oil volume ratio was 500, the pressure was 6.0 MPa, and the reaction conditions and product data are shown in Table 1.

[0113] The second-stage hydrogenation reactor (2 reactors) has an inlet temperature of 280℃, a pressure of 5.5MPa, and a fresh feed space velocity of 0.8h. -1 The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0114] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 470℃, a pressure of 6.0 MPa, and a fresh feed space velocity of 2.0 h⁻¹. -1The hydrogen-to-oil volume ratio is 2000. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0115] The preparation method of the third-stage hydrogenation catalyst is the same as in [Example 1].

[0116]

Example 6

[0117] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel. The reactor (reactor 1) inlet temperature is 50℃, the pressure is 5.5MPa, and the fresh feed space velocity is 1.2h. -1 The volume ratio of fresh oil to recycled product was 1.0:4.0, and the hydrogen-to-oil volume ratio was 800. The reaction process conditions and product composition data are shown in Table 1.

[0118] The second-stage hydrogenation reactor (2 reactors) has an inlet temperature of 290℃, a pressure of 5.0 MPa, and a fresh feed space velocity of 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 1500, and the fresh oil to recycled product volume ratio was 1.0:1.0. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0119] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 470℃, a pressure of 6.0 MPa, and a fresh feed space velocity of 2.0 h⁻¹. -1The hydrogen-to-oil volume ratio is 2000. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0120] The catalyst used in the third stage of hydrogenation is prepared as follows:

[0121] 820 g of ZSM-5 molecular sieve powder with a hydrogen form SiO2 / Al2O3 ratio of 250 (dried before use) was selected and mixed evenly with 15 g each of pseudoboehmite (containing 145 g of alumina), methylcellulose, and Tianqing powder. Then, 13 g of nitric acid was added to 600 g of water and dissolved evenly. Cerium nitrate (containing 20 g of cerium oxide) and calcium nitrate (containing 15 g of calcium oxide) were added and dissolved evenly. The solution was poured into the above mixed powder and kneaded for 35 minutes. The mixture was extruded into strips, placed at 20°C for 12 hours, dried at 110°C for 6 hours, and then calcined in a muffle furnace at 550°C for 6 hours to obtain the composite carrier (composite carrier weight percentage composition: ZSM-5 content 82%, Al2O3 content 14.5%, calcium oxide content 1.5%, cerium oxide content 2.0%), with a water absorption rate of 105%.

[0122] A soluble metal salt precursor, basic nickel carbonate, was used to prepare an impregnation solution containing 40 g of Ni. The solution volume was controlled at 160 mL. 1 g of sodium N-dodecylethylenediaminetriacetate, 0.8 g of ethanolamine, and 0.8 g of triethanolamine were added to the impregnation solution and stirred until homogeneous. 160 g of a composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method. The mixture was aged at 20 °C for 16 hours, dried at 180 °C for 3 hours, and calcined at 600 °C for 2 hours to obtain the oxidizing catalyst. Reduction at 450 °C under a hydrogen atmosphere for 40 hours yielded the reducing catalyst. The Ni dispersion in the reducing catalyst was 15.2%. The TPR (temperature programmed reduction) reduction peak temperature of the oxidizing catalyst was 389 °C.

[0123]

Example 7

[0124] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1BTX production; the first stage uses a Ni / Al2O3 catalyst containing 13% nickel, with an inlet temperature of 50℃, a pressure of 5.5MPa, and a fresh feed space velocity of 1.2h. -1 The volume ratio of fresh oil to recycled product was 1.0:4.0, and the hydrogen-to-oil volume ratio was 800. The reaction process conditions and product composition data are shown in Table 1.

[0125] The second-stage hydrogenation reactor (2 reactors) has an inlet temperature of 290℃, a pressure of 5.0 MPa, and a fresh feed space velocity of 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 1500, and the fresh oil to recycled product volume ratio was 1.0:1.0. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0126] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 410℃, a pressure of 5.5MPa, and a fresh feed space velocity of 1.0h. -1 The hydrogen-to-oil volume ratio is 1800. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0127] The catalyst used in the third stage of hydrogenation is prepared using the same method as in [Example 1].

[0128]

Example 8

[0129] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel. The reactor (reactor 1) inlet temperature is 50℃, the pressure is 5.5MPa, and the fresh feed space velocity is 1.2h. -1 The volume ratio of fresh oil to recycled product was 1.0:4.0, and the hydrogen-to-oil volume ratio was 800. The reaction process conditions and product composition data are shown in Table 1.

[0130] The second-stage hydrogenation uses a Ni-Mo / TiO2-SiO2-Al2O3 catalyst. The reactor (2 reactors) inlet temperature is 290℃, the pressure is 5.0MPa, and the fresh feed space velocity is 1.0h. -1 The hydrogen-to-oil volume ratio was 1500, and the fresh oil to recycled product volume ratio was 1.0:1.0. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0131] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 450℃, a pressure of 6.5MPa, and a fresh feed space velocity of 1.2h / h. -1 The hydrogen-to-oil volume ratio is 1000. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0132] The catalyst used in the third stage of hydrogenation is prepared using the same method as in [Example 1].

[0133]

Example 9

[0134] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel. The reactor (reactor 1) inlet temperature is 50℃, the pressure is 5.5MPa, and the fresh feed space velocity is 1.2h. -1 The volume ratio of fresh oil to recycled product was 1.0:4.0, and the hydrogen-to-oil volume ratio was 800. The reaction process conditions and product composition data are shown in Table 1.

[0135] The second-stage hydrogenation uses a Ni-Mo / TiO2-SiO2-Al2O3 catalyst. The reactor (2 reactors) inlet temperature is 290℃, the pressure is 5.0MPa, and the fresh feed space velocity is 1.0h. -1The hydrogen-to-oil volume ratio was 1500, and the fresh oil to recycled product volume ratio was 1.0:1.0. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0136] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 420℃, a pressure of 5.0 MPa, and a fresh feed space velocity of 0.8 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1500. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0137] The catalyst used in the third stage of hydrogenation is prepared using the same method as in [Example 1].

[0138]

Example 10

[0139] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel. The reactor (reactor 1) inlet temperature is 45℃, the pressure is 6.0MPa, and the fresh feed space velocity is 1.0h. -1 The hydrogen-to-oil volume ratio was 500, and the fresh oil to recycled product volume ratio was 1.0:5.0. The reaction conditions and product data are shown in Table 1.

[0140] The second-stage hydrogenation uses a Ni-Mo / TiO2-SiO2-Al2O3 catalyst. The reactor (2 reactors) inlet temperature is 280℃, the pressure is 5.5MPa, and the fresh feed space velocity is 0.8h. -1 The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0141] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 420℃, a pressure of 5.0 MPa, and a fresh feed space velocity of 0.8 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1500. The material from the outlet of the third reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3, producing fuel gas, C2-C4 alkanes, and a small amount of residual liquid, respectively. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product of the xylene tower is recycled to the inlet of the third reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst composition used in the three-stage hydrogenation is: the active component Ni content is 15%, and the balance is a composite support.

[0142] The catalyst used in the third stage of hydrogenation is prepared as follows:

[0143] Take 832 g of ZSM-5 molecular sieve powder (dried before use) with a hydrogen form SiO2 / Al2O3 molar ratio of 150, mix it evenly with 15 g each of pseudoboehmite (containing 150 g of alumina), methylcellulose, and Tianqing powder; then add 8 g of nitric acid and 5 g of citric acid to 600 g of water and dissolve evenly, then add cerium nitrate (containing 8 g of cerium oxide) and calcium nitrate (containing 10 g of calcium oxide) and dissolve evenly. Pour the solution into the above mixed powder and knead for 35 minutes, extrude into strips, place at 20°C for 12 hours, dry at 110°C for 6 hours, and calcine at 600°C for 5 hours in a muffle furnace to obtain the composite carrier (composite carrier weight percentage composition: ZSM-5 content 83.2%, Al2O3 content 15%, calcium oxide content 1%, cerium oxide content 0.8%), with a water absorption rate of 102%.

[0144] A soluble metal salt precursor, basic nickel carbonate, was used to prepare an impregnation solution containing 30 g of Ni. The solution volume was controlled at 170 mL. 0.0085 g of sodium N-dodecylethylenediaminetriacetate and 0.0085 g of triethanolamine were added to the impregnation solution and stirred until homogeneous. 170 g of a composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method. The mixture was aged at 25 °C for 16 hours, dried at 100 °C for 4 hours, and calcined at 400 °C for 4 hours to obtain the oxidized catalyst. Reduction at 350 °C under a hydrogen atmosphere for 48 hours yielded the hydrocracking catalyst. The Ni dispersion in the reduced catalyst was 7.7%. The peak reduction temperature of the active component under a hydrogen atmosphere was 415 °C.

[0145]

Comparative Example 1

[0146] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel. The reactor (reactor 1) inlet temperature is 45℃, the pressure is 6.0MPa, and the fresh feed space velocity is 1.0h. -1 The hydrogen-to-oil volume ratio was 500, and the fresh oil to recycled product volume ratio was 1.0:5.0. The reaction conditions and product data are shown in Table 1.

[0147] The second-stage hydrogenation uses a Ni-Mo / TiO2-SiO2-Al2O3 catalyst. The reactor (2 reactors) inlet temperature is 280℃, the pressure is 5.5MPa, and the fresh feed space velocity is 0.8h. -1 The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0148] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 420℃, a pressure of 5.0 MPa, and a fresh feed space velocity of 0.8 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1500. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0149] The catalyst used in the third stage of hydrogenation is prepared as follows:

[0150] 832 g of ZSM-5 molecular sieve powder with a hydrogen form SiO2 / Al2O3 ratio of 150 (dried before use) was selected and mixed evenly with 15 g each of pseudoboehmite (containing 150 g of alumina), methylcellulose, and Tianqing powder. Then, 8 g of nitric acid and 5 g of citric acid were dissolved evenly in 600 g of water. Cerium nitrate (containing 8 g of cerium oxide) and calcium nitrate (containing 10 g of calcium oxide) were then added and dissolved evenly. The solution was poured into the above mixed powder and kneaded for 35 minutes. The mixture was then extruded into strips, placed at 20°C for 12 hours, dried at 110°C for 6 hours, and then calcined in a muffle furnace at 600°C for 5 hours to obtain the composite carrier (composite carrier weight percentage composition: ZSM-5 content 83.2%, Al2O3 content 15%, calcium oxide content 1%, cerium oxide content 0.8%), with a water absorption rate of 102%.

[0151] A Ni-containing impregnation solution of 30 g was prepared using a soluble metal salt precursor. The solution volume was controlled at 170 mL. 170 g of a composite support was loaded with an equal volume of the impregnation solution using a rotary drum spray method. The mixture was aged at 25 °C for 16 h, dried at 100 °C for 4 h, and calcined at 400 °C for 4 h to obtain the oxidizing catalyst. Reduction at 350 °C under a hydrogen atmosphere for 48 h yielded the reducing catalyst. The Ni dispersion in the reducing catalyst was 4.1%. The temperature-programmed reduction (TPR) spectrum of the oxidizing catalyst is shown below. Figure 6 ,Depend on Figure 6 It can be seen that the peak reduction temperature of the active component under hydrogen atmosphere is 440℃, indicating that the active component is poorly dispersed, difficult to reduce, and has low activity.

[0152] [Comparative Example 2]

[0153] Using aromatic-rich cracked oil with an initial boiling point of 165℃ and a final boiling point of 260℃ as feedstock, the bromine value is 65gBr2 / 100g oil, the aromatic content is greater than 98%, the sulfur content is 120ug / mL, and the nitrogen content is 42ug / mL. A three-stage circulating hydrogenation process is adopted. Figure 1 BTX production; the first stage of hydrogenation uses a Ni / Al2O3 catalyst containing 13% nickel. The reactor (reactor 1) inlet temperature is 45℃, the pressure is 6.0MPa, and the fresh feed space velocity is 1.0h. -1 The hydrogen-to-oil volume ratio was 500, and the fresh oil to recycled product volume ratio was 1.0:5.0. The reaction conditions and product data are shown in Table 1.

[0154] The second-stage hydrogenation uses a Ni-Mo / TiO2-SiO2-Al2O3 catalyst. The reactor (2 reactors) inlet temperature is 280℃, the pressure is 5.5MPa, and the fresh feed space velocity is 0.8h. -1 The hydrogen-to-oil volume ratio was 1200, and the fresh oil to recycled product volume ratio was 1.0:0.5. Reaction process conditions and product composition data are shown in Tables 2 and 3. The catalyst used in the second-stage hydrogenation process had the following composition: TiO2-SiO2-Al2O3 content of 78% (TiO2 8.5%, SiO2 9.5%, Al2O3 82%), NiO content of 9%, and MoO3 content of 13%.

[0155] The third-stage hydrogenation reactor (3 reactors) has an inlet temperature of 420℃, a pressure of 5.0 MPa, and a fresh feed space velocity of 0.8 h⁻¹. -1The hydrogen-to-oil volume ratio is 1500. The material from the third stage hydrogenation reactor is separated into gaseous and liquid phases by separator 1. The gaseous material passes through separators 2 and 3 to produce fuel gas, C2-C4 alkanes, and a small amount of residual liquid. The liquid phase material from separator 1 passes through a benzene stripping tower, a toluene tower, and a xylene tower to obtain pure benzene, toluene, and mixed C8 aromatics, respectively. The bottom product from the xylene tower is recycled to the inlet of the third stage hydrogenation reactor, and some heavy components are discharged from the system. The reaction process conditions are shown in Table 4, and the composition data of the reaction products are shown in Table 5. The catalyst used in the third stage hydrogenation has the following composition: the active component Ni content is 15%, and the balance is a composite support.

[0156] The catalyst used in the third stage of hydrogenation is prepared as follows:

[0157] 840 g of ZSM-5 molecular sieve powder with a hydrogen form SiO2 / Al2O3 ratio of 150 (dried before use) was selected and mixed evenly with 15 g each of pseudoboehmite (containing 150 g of alumina), methylcellulose, and Tianqing powder. Then, 8 g of nitric acid and 5 g of citric acid were added to 600 g of water and dissolved evenly. Then, calcium nitrate (containing 10 g of calcium oxide) was added and dissolved evenly. The solution was poured into the above mixed powder and kneaded for 35 minutes. The mixture was then extruded into strips, placed at 20°C for 12 hours, dried at 110°C for 6 hours, and calcined in a muffle furnace at 600°C for 5 hours to obtain the composite carrier (composite carrier weight percentage composition: ZSM-5 content 84%, Al2O3 content 15%, calcium oxide content 1%), with a water absorption rate of 103%.

[0158] A soluble metal salt precursor, basic nickel carbonate, was used to prepare an impregnation solution containing 30 g of Ni. The solution volume was controlled at 170 mL. 1 g of sodium N-dodecylethylenediaminetriacetate and 1 g of triethanolamine were added to the impregnation solution and stirred until homogeneous. An equal volume of the impregnation solution was loaded onto a 170 g composite support using a rotary drum spray method. The mixture was aged at 25 °C for 16 hours, dried at 100 °C for 4 hours, and calcined at 400 °C for 4 hours to obtain the oxidized catalyst. Reduction at 350 °C under a hydrogen atmosphere for 48 hours yielded the reduced catalyst. The Ni dispersion in the reduced catalyst was 7.6%. The peak reduction temperature of the active component under a hydrogen atmosphere was 427 °C.

[0159] Table 1

[0160]

[0161] Note: *Recycling ratio refers to the volume ratio of fresh material to reaction products used for recycling.

[0162] Table 2

[0163]

[0164]

[0165] Note: *Recycling ratio refers to the volume ratio of fresh material to reaction products used for recycling.

[0166] Table 3

[0167]

[0168] Table 4

[0169]

[0170]

[0171] Table 5

[0172]

[0173] Note: **The data in the table are from 400 hours of online reaction.

[0174] The embodiments described above are merely detailed descriptions of the technical solutions of the present invention, but the present invention is not limited to the above embodiments, that is, the present invention does not depend on the steps described in the above embodiments to be implemented. In summary, any improvements made to the present invention by those skilled in the art, including the substitution of the raw materials and additives described in the present invention, the selection of specific implementation methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for producing BTX from rich aromatic light cracked distillate oil, comprising a three-stage hydrogenation process: the first stage is selective hydrogenation of dienes, the second stage is selective hydrogenation of polycyclic aromatic hydrocarbons (PAHs), and the third stage is selective hydrocracking. The product of the first stage hydrogenation has a bromine value of less than 25 gBr2 / 100g oil; the product of the second stage hydrogenation has a PAH content of less than 2% and an aromatic hydrocarbon retention rate of greater than 93%; and the total liquid phase product yield of the third stage hydrogenation product is greater than 80%, with a BTX yield of greater than 50%. The catalyst used in the third stage of hydrogenation comprises, by weight percentage, the following components: a) 5%~20% Ni; b) 0.01%~5.00% CeO2; c) 55.00%~89.99% ZSM-5; d) 5%~20% adhesive; in, The catalyst used in the third stage hydrogenation has a TPR hydrogen atmosphere reduction temperature of less than 420℃ and a dispersion of Ni greater than 7.5%.

2. The method according to claim 1, characterized in that, The reaction conditions of the first stage hydrogenation are as follows: reactor inlet temperature 40-90℃, fresh feed air speed 0.8-2.0h -1 , circulation ratio 1.0:2.0-1.0:7.0, hydrogen / oil volume ratio 300-1000, pressure 2-8MPa.

3. The method according to claim 1, characterized in that, The reaction conditions of the second stage hydrogenation are as follows: reactor inlet temperature 240-350℃, fresh feed air speed 0.8-2.0h -1 , circulation ratio 1.0:0.3-1.0:2.0, hydrogen / oil volume ratio 500-2000, pressure 2-8MPa.

4. The method according to claim 1, characterized in that, The reaction conditions for the third-stage hydrogenation are: reactor inlet temperature 380~480℃, fresh feed space velocity 0.6~4.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500-2000, and the pressure is 2-8 MPa.

5. The method according to claim 1, characterized in that, The rich aromatic light cracked distillate oil has an initial boiling point of 85~170℃ and a final boiling point of 220~280℃. The feed composition is: sulfur content <600ug / mL, nitrogen content <300ug / mL, and aromatic content >90wt%.

6. The method according to claim 1, characterized in that, The catalyst used in the third stage of hydrogenation has a Ni dispersion of 9% to 20%.

7. The method according to claim 6, characterized in that, The catalyst used in the third stage of hydrogenation contains, by weight percentage, 10% to 15% Ni, 0.5% to 3.0% CeO2, 8% to 15% binder, and the balance is ZSM-5.

8. The method according to claim 6 or 7, characterized in that, The catalyst used in the third stage of hydrogenation contains 0.1% to 3.0% alkaline earth metal oxides.

9. The method according to claim 8, characterized in that, The alkaline earth metal oxides in the catalyst used in the third stage of hydrogenation are calcium oxide and / or magnesium oxide.

10. The method according to claim 6, characterized in that, The TPR hydrogen atmosphere reduction temperature of the catalyst used in the third stage hydrogenation is below 400°C.

11. The method according to claim 10, characterized in that, The catalyst used in the third stage hydrogenation has a TPR hydrogen atmosphere reduction temperature of less than 390℃ and a dispersion of Ni greater than 10%.

12. The method according to claim 11, characterized in that, The dispersion of Ni, the active component, in the catalyst used in the third stage of hydrogenation is 11% to 20%.

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