CN114456837B

CN114456837B - Method for reducing polycyclic aromatic hydrocarbon in diesel oil

Info

Publication number: CN114456837B
Application number: CN202011136700.5A
Authority: CN
Inventors: 刘丽; 代萌; 杨成敏; 段为宇; 郭蓉; 周勇; 李扬; 姚运海; 郑步梅; 孙进
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2020-10-22
Filing date: 2020-10-22
Publication date: 2023-07-04
Anticipated expiration: 2040-10-22
Also published as: CN114456837A

Abstract

The invention discloses a method for reducing polycyclic aromatic hydrocarbon in diesel oil, which comprises the following steps: the gas phase components of the diesel raw material after flash evaporation enter a first hydrogenation reaction zone to carry out hydrogenation reaction; the liquid phase component after flash evaporation enters a second hydrogenation reaction zone to carry out hydrodesulfurization and denitrification reactions, the effluent of the second hydrogenation reaction zone enters a third hydrogenation reaction zone downwards to carry out polycyclic aromatic hydrocarbon hydrogenation saturation reaction, and the product of the third hydrogenation reaction zone is discharged from the bottom of the reactor; the second hydrogenation reaction zone is filled with semi-sulfided bulk hydrogenation catalyst comprising a group VIB metal sulfide, a group VIII metal oxide, and Al ₂ O ₃ And an auxiliary agent; based on the weight of the bulk hydrofining catalyst, the content of the VIB group metal sulfide is 40% -70%, and the content of the VIII group metal oxide is 3% -25%. The method uses the low-grade diesel oil mixed oil as raw material to produce the high-quality diesel oil blending component of ultra-low sulfur and low polycyclic aromatic hydrocarbon under the conditions of simple flow, low energy consumption and low cost by the cooperation of the catalyst and the technological flow.

Description

Method for reducing polycyclic aromatic hydrocarbon in diesel oil

Technical Field

The invention belongs to the field of clean oil refining, and particularly relates to a method for reducing diesel polycyclic aromatic hydrocarbon.

Background

With the demand of diesel quality upgrading, the diesel in China has finished the quality upgrading of the national VI standard at present, wherein the sulfur content is not more than 10ppm, and the polycyclic aromatic hydrocarbon content is not more than 7%. According to the foreign diesel quality standard, the polycyclic aromatic hydrocarbon content in the diesel in the individual areas of the united states is required to be lower, and the further reduction of the polycyclic aromatic hydrocarbon content in the diesel is an important development direction of diesel quality upgrading.

CN 102465021B discloses a diesel oil combined hydrogenation process. The method is that firstly, the diesel oil raw material is cut into light and heavy components, the light components enter a liquid phase hydrogenation reactor for reaction, the heavy components enter a gas phase circulation hydrogenation reactor for reaction, gas phase hydrogenation products (or gas phase hydrogenation products and liquid phase hydrogenation products) are separated, the obtained liquid can be directly taken as products to be discharged out of the device, or circulated to the liquid phase hydrogenation reactor, and the liquid phase hydrogenation products are taken as products to be discharged out of the device. The method comprises the steps of cutting raw oil, then respectively carrying out hydrotreatment, wherein sulfur-containing compounds and polycyclic aromatic hydrocarbons which are difficult to remove are mainly in heavy components, the heavy components enter a gas-phase circulating hydrogenation reactor for reaction, the pressure and the temperature of the reaction are required to be increased for removing sulfides and polycyclic aromatic hydrocarbons, the hydrogen-oil ratio is increased, a large amount of hydrogen and energy are consumed, and the increase of the temperature is not used for the hydrogenation saturation of polycyclic aromatic hydrocarbons. Meanwhile, the invention cuts the diesel oil raw material into light and heavy components, fractionation equipment is required to be added, the equipment investment cost is increased, the light components are subjected to liquid phase hydrogenation reaction, the temperature of the cut light components is required to be reduced to be converted into liquid phase, the energy consumption is increased, and the energy waste is caused.

CN 102311794B discloses a diesel hydrogenation process. The method comprises the following steps: the diesel raw material enters a conventional gas-phase circulation hydrogenation reactor for reaction, and effluent is subjected to gas-liquid separation; after saturated dissolved hydrogen, the obtained liquid phase enters a liquid phase circulation hydrogenation reactor for carrying out, and after passing through a hydrogen sulfide removal reactor, the liquid phase circulation oil circulates back to an inlet of the liquid phase hydrogenation reactor; the gas-phase circulation hydrogenation is used for preprocessing the raw oil, and the sulfur content in the generated oil is reduced to below 500 mug/g. Wherein the process conditions of the conventional gas-phase circulation hydrogenation reactor are as follows: reaction temperature280-400 ℃, 3.0-10.0 MPa of reaction pressure and 1.0h of liquid hourly space velocity ^-1 ~6.0h ^-1 The volume ratio of hydrogen to oil is 100-1000; the technological conditions of the liquid phase circulation hydrogenation reactor are as follows: the reaction temperature is 300-420 ℃, the reaction pressure is 3.0-10.0 MPa, and the liquid hourly space velocity is 1.0-6.0 h ^-1 . According to the method, most of sulfur compounds in raw oil are removed in a gas-phase circulating hydrogenation reactor, and macromolecule sulfur compounds and polycyclic aromatic hydrocarbons which are difficult to remove are removed in a liquid-phase circulating hydrogenation reactor.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for reducing polycyclic aromatic hydrocarbon in diesel oil. According to the method, the catalyst and the process flow are matched, so that the high-quality diesel blending component of ultralow-sulfur and low-polycyclic aromatic hydrocarbon can be produced by taking the low-quality diesel mixed oil as a raw material under the conditions of simple flow, low energy consumption and low cost.

The method for reducing polycyclic aromatic hydrocarbon in diesel oil comprises the following steps: the diesel oil raw material enters a flash evaporation zone of a fixed bed reactor, the gas phase components after flash evaporation upwards enter a first hydrogenation reaction zone for hydrogenation reaction, and reaction products are discharged from the top of the reactor; the liquid phase component after flash evaporation enters a second hydrogenation reaction zone downwards to carry out hydrodesulfurization and denitrification reactions, the effluent of the second hydrogenation reaction zone enters a third hydrogenation reaction zone downwards to carry out polycyclic aromatic hydrocarbon hydrogenation saturation reaction, and the product of the third hydrogenation reaction zone is discharged from the bottom of the reactor; wherein, hydrogen enters from the second hydrogenation reaction zone and the third hydrogenation reaction zone of the reactor; the second hydrogenation reaction zone is filled with semi-sulfided bulk hydrogenation catalyst comprising a group VIB metal sulfide, a group VIII metal oxide, and Al ₂ O ₃ And an auxiliary agent, wherein the group VIB metalPreferably Mo and/or W, preferably Co and/or Ni, and one or more of B, P, F, mg, zr or Si as auxiliary agents; based on the weight of the bulk hydrofining catalyst, the content of the VIB group metal sulfide is 40% -70%, preferably 50% -65%, the content of the VIII group metal oxide is 3% -25%, preferably 3% -15%, the content of the auxiliary agent is 3% -15%, preferably 3% -10% and the content of the Al is 3% -15% of the oxide ₂ O ₃ 24% -54%, preferably 25% -42%; the VIB metal sulfide is distributed in the catalyst phase and the surface phase, the weight ratio of the surface phase VIB metal sulfide to the bulk VIB metal sulfide is 2.5:1-7.5:1, and the VIII metal oxide is distributed in the catalyst surface phase; the phase of the VIB metal sulfide is characterized by SEM (scanning electron microscope) energy spectrum and TEM (electron microscope), and the surface phase of the VIB metal sulfide and the surface phase of the VIII metal sulfide are analyzed by XPS (x-ray diffraction) energy spectrum; the third hydrogenation reaction zone is filled with a noble metal hydrogenation catalyst.

In the method, the diesel oil raw material is one or more of straight-run diesel oil, catalytic cracking diesel oil, coking diesel oil and boiling bed residual oil hydrogenated diesel oil; the distillation range of the diesel oil raw material is 220-400 ℃, the sulfur content is no more than 15000 mug/g, the nitrogen content is no more than 1000 mug/g, and the cetane number is no less than 35.

In the method of the invention, the flash evaporation zone is used for separating light fraction below 280 ℃ from the raw material, the light fraction enters the first hydrogenation reaction zone as a gas phase component, and the heavy fraction above 280 ℃ enters the second hydrogenation reaction zone as a liquid phase component.

In the method, the first hydrogenation reaction zone is used for desulfurizing and denitrifying gas phase components (light fraction), and Mo-Ni and/or Mo-Co type light fraction oil hydrogenation catalysts, such as FH-40 series light fraction oil hydrogenation special catalysts developed by FRIPP, are filled in the first hydrogenation reaction zone. The technological conditions of the first hydrogenation reaction zone are as follows: the pressure is 1.0-12.0 MPa, preferably 2.0-8.0 MPa, wherein the hydrogen partial pressure accounts for 40% -70% of the total pressure ratio; volume space velocity is 0.1-10.0 h ^-1 Preferably 0.5 to 6.0 hours ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The feeding temperature is 150-330 ℃, preferably 180-300 ℃; hydrogen oil volume ratio 10: 1-800: 1, preferably 100: 1-400: 1.

in the process of the present invention, the second hydrogenationThe reaction zone is used for the deep desulfurization and denitrification of liquid phase components (heavy fractions). The process conditions of the second hydrogenation reaction zone are as follows: the pressure is 1.0-12.0 MPa, preferably 6.0-10.0 MPa, wherein the hydrogen partial pressure accounts for 50% -90% of the total pressure ratio; volume space velocity is 0.1-10.0 h ^-1 Preferably 0.5 to 3.0 hours ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The reaction temperature is 200-400 ℃, preferably 280-350 ℃; hydrogen oil volume ratio 10: 1-800: 1, preferably 100: 1-400: 1.

the preparation method of the semi-vulcanized bulk hydrogenation catalyst comprises the following steps:

(1) Preparing a mixed solution A containing VIB group metal and an aluminum source, and carrying out parallel flow gel forming reaction on the mixed solution A and a precipitator to generate slurry I containing VIB group metal and aluminum precipitate;

(2) Pulping and uniformly mixing the slurry I obtained in the step (1) and an auxiliary agent precursor, filtering, washing, drying and forming to obtain a catalyst precursor I;

(3) Drying and roasting the catalyst precursor I obtained in the step (2), and then vulcanizing to obtain a catalyst precursor II containing a VIB group metal sulfide;

(4) Impregnating the catalyst precursor II obtained in the step (3) with an impregnating solution containing a group VIII metal, and then drying and roasting in an inert atmosphere to obtain the semi-vulcanized type bulk phase hydrogenation catalyst.

In the mixed solution A of the step (1), the weight concentration of the VIB group metal in terms of oxide is 10-100 g/L, preferably 20-90 g/L, and Al is Al ₂ O ₃ The weight concentration is 2-60 g/L, preferably 8-40 g/L. When preparing the mixed solution A, one or more of phosphate or ammonium salt of VIB group metal is generally adopted; the aluminum source can be one or more of aluminum nitrate, aluminum sulfate, aluminum chloride or aluminum acetate.

The precipitant in the step (1) is one or more of sodium carbonate, sodium bicarbonate, ammonia water, sodium hydroxide, potassium carbonate or potassium bicarbonate water solution, and the concentration of the precipitant is 0.5 mol/L-3.0 mol/L.

The parallel flow gel forming reaction temperature in the step (1) is 30-90 ℃, preferably 40-80 ℃. The pH value is controlled to be 6.0-11.0, preferably 7.0-9.0, and the gel forming time is controlled to be 0.2-4.0 hours, preferably 0.5-3.0 hours.

In the step (2), the auxiliary agent precursor is one or more of boric acid, phosphoric acid, ammonium hydrofluoric acid, magnesium nitrate, sodium silicate or zirconium nitrate, and the concentration of the auxiliary agent aqueous solution is 1.0-3.0 mol/L; after the auxiliary agent and the slurry I are uniformly mixed, the pH value is controlled to be 7.0-9.0.

The washing, drying and shaping described in step (2) may be carried out by methods conventional in the art. The washing is usually carried out by adopting deionized water or solution containing decomposable salts (such as ammonium acetate, ammonium chloride, ammonium nitrate and the like) to wash until the solution is neutral. The drying conditions were as follows: drying at 90-200 ℃ for 3-6 hours. Conventional molding aids, such as one or more of peptizers, extrusion aids, and the like, may be added as needed during the molding process. The peptizing agent is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, oxalic acid and the like, the extrusion assisting agent is one or more of sesbania powder, carbon black, graphite powder, citric acid and the like which are favorable for extrusion molding, and the consumption of the extrusion assisting agent accounts for 1-10wt% of the total dry matter of the materials.

The drying conditions in the step (3) are as follows: the drying temperature is 90-200 ℃, the drying time is 3-6 hours, and the roasting conditions are as follows: the roasting temperature is 400-800 ℃, and the roasting time is 3-6 hours.

The vulcanization treatment in the step (3) is well known to those skilled in the art, and is usually dry vulcanization or wet vulcanization, wherein the dry vulcanizing agent is hydrogen sulfide, and the wet vulcanizing agent is one or two of carbon disulfide, dimethyl disulfide, methyl sulfide and n-butyl sulfide; the vulcanization pressure is 3.2-6.4 MPa, the vulcanization temperature is 250-400 ℃, and the vulcanization time is 4-12 h.

The first step of step (4)

The preparation method of the impregnating solution of the group metal is well known to the skilled in the art, such as nitrate, acetate, sulfate solution and the like are generally adopted, the mass concentration of the impregnating solution is 0.1 g/mL-1.0 g/mL, and the same volume impregnation can be adoptedThe manner of the stains, the->

The group metal is preferably Ni and/or Co.

The inert atmosphere in the step (4) is N ₂ And one or more of inert gases; the drying temperature is 20-90 ℃, and the drying time is 4-16 hours; the roasting temperature is 200-500 ℃, and the roasting time is 2-5 hours.

In the method of the invention, the third hydrogenation reaction zone is used for generating the polycyclic aromatic hydrocarbon hydrogenation saturation reaction of heavy fractions, the noble metal hydrogenation catalyst in the third hydrogenation reaction zone comprises a carrier, an active component and an auxiliary agent, wherein the carrier is alumina, the active component is Pt and/or Pd based on the weight of the carrier, and the auxiliary agent is Ni and/or Co. Based on the weight of the catalyst, the active component is 0.05 to 5.0 weight percent, preferably 0.1 to 0.3 weight percent, the auxiliary agent is 1 to 10 weight percent, preferably 3 to 6 weight percent, and the rest is the carrier. The specific surface area of the catalyst is 300-400m ² Per g, pore volume of 0.4-0.6cm ³ And/g, the crushing strength is 150-250N/cm. The noble metal catalyst may be commercially available as desired, or may be prepared by methods conventional in the art. The process conditions of the third hydrogenation reaction zone are as follows: the pressure is 1.0-12.0 MPa, preferably 4.0-6.0 MPa, which is a pure liquid phase reaction zone, and the volume ratio of standard hydrogen to oil is 2-50, preferably 10-30; volume space velocity is 0.1-8.0 h ^-1 Preferably 0.5 to 6.0 hours ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The reaction temperature is 150-300 ℃, preferably 180-250 ℃; hydrogen oil volume ratio 10: 1-800: 1, preferably 100: 1-400: 1.

compared with the existing diesel hydrogenation technology, the method provided by the invention can effectively reduce the content of polycyclic aromatic hydrocarbon in diesel and produce high-quality diesel. After the raw oil enters the flash evaporation zone, the light fraction enters the first hydrogenation reaction zone, and the alkaline nitrides such as mercaptan, thioether, pyridine and the like in the light fraction are subjected to hydrogenation removal reaction, so that the occupation of the compounds on the hydrogenation reaction active sites of the polycyclic aromatic hydrocarbon can be reduced. The heavy fraction enters the second hydrogenation reaction zone after the raw oil enters the flash evaporation zone, macromolecular sulfur-containing compounds and nitrogen-containing compounds are subjected to hydrogenation removal reaction in the reaction zone, the exothermic heat in the reaction process is serious, but the high-activity semi-sulfidic hydrogenation catalyst can be used for hydrodesulfurization and denitrification at a lower reaction temperature, and in addition, the reaction zone is a gas-liquid countercurrent reaction environment, heat generated by the reaction can be taken away in time, and the macromolecular compounds such as polycyclic aromatic hydrocarbon and the like are prevented from coking reaction on the catalyst in a high-temperature environment; meanwhile, the semi-vulcanized bulk phase catalyst in the second hydrogenation reaction zone has high content of active sites of the second class active center with high hydrogenation activity, and can timely hydrogenate macromolecular compounds to prevent the macromolecular compounds from coking on the surface of the catalyst; the catalyst does not need to be vulcanized, the metal oxide which is difficult to be vulcanized is vulcanized in advance, the metal oxide which is easy to be vulcanized in the semi-vulcanized catalyst can be vulcanized gradually along with the hydrogen sulfide generated by the reaction product, the temperature flying caused by the over high initial activity of the reaction can be weakened, and meanwhile, the semi-vulcanized catalyst can keep higher reaction activity. In addition, in the initial stage of the reaction, sulfide (mainly sulfide which is not removed and can be benzothiophene and the like) in the product of the second reaction zone can passivate the noble metal catalyst of the third reaction zone, so that the noble metal catalyst is prevented from being excessively high in activity in the initial stage of the reaction to cause the temperature runaway; with the increase of the activity of the catalyst in the second reaction zone, sulfide in the product of the second reaction zone is reduced, the passivation effect on the noble metal catalyst can not be continuously generated, and the process conditions can be matched with the activity of the noble metal catalyst. In addition, macromolecular sulfur-containing compounds and nitrogen-containing compounds need to be removed after hydrogenation, and a competition reaction is formed between the macromolecular sulfur-containing compounds and the nitrogen-containing compounds and the hydrogenation saturation of the polycyclic aromatic hydrocarbon, and the removal of the sulfur-containing compounds and the nitrogen-containing compounds in the reaction zone is beneficial to the hydrogenation saturation of the polycyclic aromatic hydrocarbon, and meanwhile, the noble metal catalyst in the hydrogenation reaction zone III is protected. The third hydrogenation reaction zone has lower reaction temperature and high saturated hydrogen content, is favorable for the hydrogenation saturation of the polycyclic aromatic hydrocarbon, has high hydrogenation activity of the noble metal catalyst on the polycyclic aromatic hydrocarbon, prevents the supersaturation of the polycyclic aromatic hydrocarbon, and inhibits the reduction of the condensation point of the diesel oil product.

Drawings

FIG. 1 is a schematic diagram of the method for reducing diesel polycyclic aromatic hydrocarbons according to the present invention.

In the figure: 1-raw material, 2-hydrogen, 3-first hydrogenation reaction zone, 4-flash evaporation zone, 5-second hydrogenation reaction zone, 6-third hydrogenation reaction zone, 7-low sulfur low nitrogen light diesel oil component, 8-low sulfur, low nitrogen, low polycyclic aromatic hydrocarbon heavy diesel oil component and 9-low polycyclic aromatic hydrocarbon high quality diesel oil.

Detailed Description

The invention will now be described in more detail with reference to the accompanying drawings and examples, which are not intended to limit the invention thereto.

The preparation method of the noble metal hydrogenation catalyst comprises the following steps:

(1) And (3) dipping the solution containing the palladium compound and/or the platinum compound into an alumina carrier, and drying and roasting to obtain the catalyst precursor.

(2) And (3) dipping the solution containing the auxiliary agent into the catalyst precursor prepared in the step (1), and drying, roasting and reducing to obtain the catalyst.

In the preparation method of the noble metal hydrogenation catalyst, the palladium-containing compound in the step (1) is selected from palladium chloride, palladium nitrate, palladium acetate, sodium tetrachloropalladate, dichlorotetraammine palladium, trifluoroacetate palladium, diacetyl acetone palladium or hexafluoroacetyl acetone palladium, and the concentration of the solution is 0.001-0.5g/mL calculated by palladium element.

In the preparation method of the noble metal hydrogenation catalyst, the platinum-containing compound in the step (1) is selected from chloroplatinic acid, tetraamminoplatinum dichloride, ammonium chloroplatinate, platinum trichloride, platinum tetrachloride, dicarbonyl platinum dichloride, dinitrodiammine platinum or sodium tetranitroplatinate, and the solution concentration is 0.001-0.5g/mL calculated by platinum element.

In the preparation method of the noble metal hydrogenation catalyst, the drying conditions in the step (1) are as follows: drying at 80-150 ℃ for 3-6h, and roasting under the conditions: roasting for 3-8h at 400-600 ℃.

In the preparation method of the noble metal hydrogenation catalyst, the auxiliary solution in the step (2) is one or more of cobalt nitrate, cobalt acetate, nickel nitrate and nickel acetate, and the concentration of the auxiliary solution is 0.01-1.0 g/mL in terms of oxide.

In the preparation method of the noble metal hydrogenation catalyst, the drying temperature in the step (2) is 20-90 ℃ and the drying time is 4-16 hours; the roasting temperature is 200-500 ℃ and the roasting time is 2-5 hours; the reduction treatment conditions are as follows: reducing for 3-10h in hydrogen atmosphere at 300-600 ℃ and 0.1-3.0 MPa.

The noble metal catalyst was prepared in example 1:

example 1

Chloroplatinic acid was dissolved in deionized water at a platinum concentration of 0.002g/mL, and the chloroplatinic acid solution was immersed in an alumina carrier in an equal volume, dried at 120 ℃ for 6 hours, and then calcined at 450 ℃ for 5 hours.

Nickel nitrate is dissolved in deionized water, wherein the concentration of nickel oxide is 0.02g/mL, nickel nitrate solution is impregnated in the catalyst precursor in an equal volume, then dried at 90 ℃ for 5 hours, roasted at 250 ℃ for 3 hours, and then reduced in a hydrogen atmosphere at 400 ℃ for 3.0MPa for 6 hours, so that the noble metal catalyst C3-1 is obtained, wherein the content of metal platinum is 0.25%, and the content of nickel is 3.5%.

Semi-sulfided catalysts were prepared in examples 2-5:

example 2

Dissolving ammonium metatungstate and aluminum chloride in deionized water to prepare a mixed solution A, wherein WO is contained in the mixed solution A ₃ The weight concentration of (C) is 80g/L, al ₂ O ₃ The weight concentration of (C) is 50g/L. Slowly adding 1.0mol/L sodium hydroxide into 1L solution A under stirring, maintaining the gelling temperature at 75 ℃, controlling the pH value at 7-8 at the end, and controlling the gelling time at 60 minutes to obtain tungsten and aluminum-containing precipitate slurry I.

And (3) uniformly mixing 160mL of 1.0mol/L magnesium nitrate solution with the slurry I, regulating the pH value to 7-8 by using ammonia water, washing with deionized water for three times, filtering, and drying at 110 ℃ for 5 hours to obtain mixed powder. Mixing 150g of the mixed powder with 5g of nitric acid, 5g of starch and 60g of deionized water uniformly, kneading, extruding, molding, drying at 100deg.C for 3h, roasting at 550deg.C for 3h, and adding a solution containing 1.5% H ₂ S, carrying out vulcanization treatment on hydrogen at 320 ℃, under 6.0MPa for 8 hours, and then carrying out vulcanization treatment on the hydrogen at N ₂ And cooling to room temperature in the atmosphere to obtain a catalyst precursor II.

42.2g of Ni (NO ₃ ) ₂ •6H ₂ O was dissolved in 50mL of deionized water, isovolumetric immersed in precursor II, then in N ₂ Drying for 4h at 80 ℃ and roasting for 3h at 330 ℃ under the atmosphere to obtain the catalyst C2-1.

Example 3

Dissolving ammonium meta-molybdate and aluminum sulfate in deionized water to prepare a mixed solution A, wherein MoO is contained in the mixed solution A ₃ The weight concentration of (C) is 80g/L, al ₂ O ₃ The weight concentration of (C) is 50g/L. Slowly adding 1.0mol/L sodium hydroxide into 1L solution A under stirring, maintaining the gelling temperature at 70 ℃, controlling the pH value at 7-8 at the end, and controlling the gelling time at 90 minutes to obtain molybdenum and aluminum containing precipitate slurry I.

100mL of 1.0mol/L zirconium nitrate solution and the slurry I are uniformly mixed, then ammonia water is used for adjusting the pH value to 7-8, deionized water is used for washing three times, and the mixed powder is obtained after filtering and drying at 120 ℃ for 4 hours. Mixing 150g of the mixed powder with 10g of phosphoric acid, 5g of starch and 60g of deionized water uniformly, kneading, extruding, molding, drying at 110 ℃ for 3h, roasting at 650 ℃ for 2h, and adopting a solution containing 1.5% of H ₂ S, hydrogen is vulcanized, the vulcanization temperature is 330 ℃, the vulcanization pressure is 5.6MPa, the vulcanization time is 6h, and then the vulcanization is carried out on N ₂ And cooling to room temperature in the atmosphere to obtain a catalyst precursor II.

42.2g of Ni (NO ₃ ) ₂ •6H ₂ O was dissolved in 50mL of deionized water, isovolumetric immersed in precursor II, then in N ₂ Drying for 4h at 100 ℃ and roasting for 3h at 300 ℃ under the atmosphere to obtain the catalyst C2-2.

Example 4

160mL of 1.0mol/L zirconium nitrate solution is uniformly mixed with the slurry I, then ammonia water is used for adjusting the pH value to 7-8, deionized water is used for washing three times, and the mixed powder is obtained after filtration and drying at 100 ℃ for 10 hours. Then mixing 150g of mixed powder with 10g of phosphoric acid, 5g of starch and 60g of deionized water uniformly, kneading, extruding, shaping, drying at 110 ℃ for 3h, and roasting at 550 ℃ for 2h. Then 3wt% CS was used ₂ Is vulcanized with airspeed of 1.0h ^-1 The hydrogen-oil volume ratio is 500:1, and the vulcanizing treatment is carried out for 8 hours under the operating pressure of 6.0MPa, and then the vulcanizing treatment is carried out under N ₂ And cooling to room temperature in the atmosphere to obtain a catalyst precursor II.

32.2g of Co (NO ₃ ) ₂ •6H ₂ O was dissolved in 50mL of deionized water, isovolumetric immersed in precursor II, then in N ₂ Drying for 4h at 100 ℃ and roasting for 4h at 300 ℃ under the atmosphere to obtain the catalyst C2-3.

Example 5

Dissolving ammonium metatungstate and aluminum chloride in deionized water to prepare a mixed solution A, wherein WO is contained in the mixed solution A ₃ The weight concentration of (C) is 80g/L, al ₂ O ₃ The weight concentration of (C) is 50g/L. Slowly adding 1.0mol/L sodium hydroxide into 1L solution A under stirring, maintaining the gelling temperature at 70 ℃, controlling the pH value at 7-8 at the end, and controlling the gelling time at 60 minutes to obtain tungsten and aluminum-containing precipitate slurry I.

And (3) uniformly mixing 160mL of 1.0mol/L magnesium nitrate solution with the slurry I, regulating the pH value to 7-8 by using ammonia water, washing with deionized water for three times, filtering, and drying at 110 ℃ for 5 hours to obtain mixed powder. Mixing 150g of the mixed powder with 5g of nitric acid, 5g of starch and 60g of deionized water uniformly, kneading, extruding, molding, drying at 120 ℃ for 3 hours, roasting at 550 ℃ for 3 hours, and adopting a solution containing 1.5% of H ₂ S, hydrogen is vulcanized, the vulcanization temperature is 340 ℃, the vulcanization pressure is 6.0MPa, the vulcanization time is 6h, and then the vulcanization is carried out on N ₂ And cooling to room temperature in the atmosphere to obtain a catalyst precursor II.

15.6g of Ni (NO ₃ ) ₂ •6H ₂ O and 20.9g of Co (NO) ₃ ) ₂ •6H ₂ O dissolves intoIn 50mL of deionized water, an equal volume of the solution was immersed in precursor II, followed by N ₂ Drying for 4h at 100 ℃ and roasting for 3h at 250 ℃ under the atmosphere to obtain the catalyst C2-4.

Comparative example 1

Dissolving ammonium metatungstate, nickel nitrate and aluminum chloride in deionized water to prepare a mixed solution A, wherein WO is contained in the mixed solution A ₃ The weight concentration of NiO is 80g/L, the weight concentration of NiO is 8g/L, al ₂ O ₃ The weight concentration of (C) is 50g/L. Slowly adding 1.0mol/L sodium hydroxide into 1L solution A under stirring, maintaining the gelling temperature at 75 ℃, controlling the pH value at 7-8 at the end, and controlling the gelling time at 60 minutes to obtain tungsten and aluminum-containing precipitate slurry I.

And (3) uniformly mixing 160mL of 1.0mol/L magnesium nitrate solution with the slurry I, regulating the pH value to 7-8 by using ammonia water, washing with deionized water for three times, filtering, and drying at 110 ℃ for 5 hours to obtain mixed powder. And then mixing 150g of mixed powder with 5g of nitric acid, 5g of starch and 60g of deionized water uniformly, kneading, extruding and molding, drying at 110 ℃ for 3 hours, and roasting at 550 ℃ for 3 hours to obtain the catalyst. Then using a solution containing 1.5% H ₂ S, hydrogen is vulcanized, the vulcanization temperature is 340 ℃, the vulcanization pressure is 5.0MPa, the vulcanization time is 8h, and then the vulcanization is carried out on N ₂ And cooling to room temperature in the atmosphere to obtain the catalyst DC-1.

Taking the attached figure 1 as an example, the implementation process of the method for reducing the polycyclic aromatic hydrocarbon in the diesel oil is as follows: the reaction raw material 1 enters a flash evaporation zone 4 under certain temperature and pressure conditions, and is separated into a gas phase and a liquid phase in the flash evaporation zone 4. The gas phase flows upward into the first hydrogenation reaction zone 3 and the liquid phase flows downward into the second hydrogenation reaction zone 5. The hydrogen 2 enters the reactor between the second hydrogenation reaction zone 5 and the third hydrogenation reaction zone 6, and after being mixed and contacted with the liquid phase material flowing downwards in the second hydrogenation reaction zone 5, the excessive hydrogen continues to flow upwards to enter the second hydrogenation reaction zone 5, and the liquid phase material dissolved and carrying the hydrogen flows downwards to enter the third hydrogenation reaction zone 6.

The first hydrogenation reaction zone 3 is subjected to gas phase reaction, and mainly subjected to hydrodesulfurization and hydrodenitrogenation reaction of the light diesel component to generate a low-sulfur low-nitrogen hydrogen diesel component 7. The second hydrogenation reaction zone 5 is subjected to gas-liquid two-phase reaction, the liquid phase is the downward flow of the heavy diesel oil fraction, the gas phase is the upward flow of the hydrogen, and the gas-liquid reverse contact is subjected to deep hydrodesulfurization and denitrification reaction. The hydrogen sulfide and low molecular hydrocarbon generated by the reaction flow upwards along with the gas phase material flow into the first hydrogenation reaction zone 3, and then flow out of the device from the top of the reactor. The hydrogenated liquid phase flow flows downwards to enter a third hydrogenation reaction zone 6 to carry out liquid phase hydrogenation reaction of the polycyclic aromatic hydrocarbon to generate a low polycyclic aromatic hydrocarbon heavy diesel oil component 8. The low-sulfur low-nitrogen hydrogen diesel component 7 and the low-polycyclic aromatic hydrocarbon heavy diesel component 8 are mixed to generate low-polycyclic aromatic hydrocarbon high-quality diesel.

Examples 6 to 10

The first, second and third hydrogenation reaction zones of this embodiment are each provided with a catalyst bed. The first hydrogenation reaction zone was charged with Ni-Mo type hydrorefining catalyst C1-1, the second hydrogenation reaction zone was charged with one of the semi-sulfided catalysts C2-1 to C2-4 prepared in example 2-5, and the third hydrogenation reaction zone was charged with noble metal catalyst C3-1 prepared in example 1. The filling ratio of the first catalyst bed layer to the second catalyst bed layer to the third catalyst bed layer is 3:5:2, the inlet temperature of raw oil is 350 ℃, and the temperature of the reaction bed layers in each reaction zone in the reaction process is stable and controllable. The catalyst properties are shown in Table 1, the raw oil is mixed oil of straight firewood, catalytic firewood and Jiao Chai, and the ratio of the three is 40:30:30, the properties of the raw oil are shown in Table 2, and the reaction process conditions and results are shown in Table 3.

Comparative example 2

The first, second and third hydrogenation reaction zones of this comparative example are each provided with a catalyst bed. The first hydrogenation reaction zone was charged with Ni-Mo type hydrorefining catalyst C1-1, the second hydrogenation reaction zone was charged with catalyst DC-1 prepared in comparative example 1, and the third hydrogenation reaction zone was charged with noble metal catalyst C3-1 prepared in example 1. The filling ratio of the first catalyst bed layer to the second catalyst bed layer to the third catalyst bed layer is 3:5:2, the inlet temperature of raw oil is 350 ℃, and the temperature of the reaction bed layers in each reaction zone in the reaction process is stable and controllable. The catalyst properties are shown in Table 1, the raw oil properties are the same as in the examples, and the reaction conditions and results are shown in Table 3.

Comparative example 3

The method for reducing polycyclic aromatic hydrocarbon in diesel oil by adopting the prior art comprises the steps of sequentially introducing raw materials into a hydrotreating reactor (a first hydrogenation reaction zone is filled with a catalyst C1-1), a hydrodesulfurization denitrification reaction zone (a second hydrogenation reaction zone is filled with a catalyst C2-1) and a hydrodearomatization reaction zone (a third hydrogenation reaction zone is filled with a catalyst C3-1), and then fractionating to obtain diesel oil blending components. Hydrogen enters at the bottom of the third hydrogenation reaction zone. The filling ratio of the first catalyst bed layer to the second catalyst bed layer to the third catalyst bed layer is 3:5:2, the inlet temperature of raw oil is 350 ℃, and the temperature of the reaction bed layers in each reaction zone in the reaction process is stable and controllable. The properties of the raw oil are the same as those of the examples, and the reaction process conditions and the results are shown in Table 3.

TABLE 1 catalyst physicochemical Properties

Catalyst numbering

C2-1

C2-2

C2-3

C2-4

DC-1

C1-1

C3-1

Tungsten sulfide content, wt%

53.2

______

56

53.6

______

Molybdenum sulfide content, wt%

______

54.6

52.3

______

Watch phase I _W Phase I _W

4.42

______

3.76

2.16

______

Watch phase I _Mo Phase I _Mo

______

4.56

5.51

______

NiO content, wt%

5.3

5.7

______

2.1

______

5.2

______

CoO content, wt%

______

4.8

3.4

______

MoO ₃ Content by weight percent

______

16.8

______

Pt content, wt%

______

0.25

Ni content, wt%

______

3.5

Nickel sulfide content, wt%

______

6.3

______

TABLE 2 oil Properties of raw materials

Oil Properties
		Density (20 ℃), g.cm ^-3	0.86
Distillation range, DEG C	220~380
		S,μg·g ^-1	14800
N,μg·g ^-1	885
		Polycyclic aromatic hydrocarbons, m%	22.5

TABLE 3 hydrogenation process conditions and results

	Example 6	Example 7	Example 8	Example 9	Comparative example 2	Comparative example 3
							Hydrogen partial pressure, MPa
An inlet	6.5	6.5	6.5	6.5	6.5
							First hydrogenation reaction zone	3.5	4.0	4.0	4.0	4.0	6.5
Second hydrogenation reaction zone	6.0	6.0	6.0	6.0	6.0	6.5
							Third hydrogenation reaction zone	Standard hydrogen-oil ratio 25	Standard hydrogen-oil ratio 25	Standard hydrogen-oil ratio 25	Standard hydrogen-oil ratio 25	Standard hydrogen-oil ratio 25	6.5
Volume space velocity, h ^-1
							First hydrogenation reaction zone	4.5	4.5	4.5	4.5	4.5	3.2
Second hydrogenation reaction zone	2.5	2.5	2.5	2.0	2.0	2.5
							Third hydrogenation reaction zone	5.5	5.5	5.5	5.5	5.5	4.5
Hydrogen to oil ratio, v/v	400	400	400	400	400	400
							Reaction temperature, DEG C
First hydrogenation reaction zone	250	250	270	270	270	320
							Second hydrogenation reaction zone	355	355	360	360	380	380
Third hydrogenation reaction zone	200	200	210	210	230	340
							Diesel oil
Sulfur, μg/g	8.2	7.2	3.6	2.3	6.9	9.8
							Nitrogen, μg/g	1.0	1.0	1.0	1.0	1.0	1.0
Polycyclic aromatic hydrocarbons, m%	6.7	5.8	4.9	3.8	6.2	8.6

As can be seen from Table 3, the present invention can produce high quality diesel oil components with low polycyclic aromatic hydrocarbon under simple flow and mild conditions, as compared with comparative example 2 and comparative example 3.

Claims

1. The method for reducing the polycyclic aromatic hydrocarbon in the diesel oil is characterized by comprising the following steps: the diesel oil raw material enters a flash evaporation zone of a fixed bed reactor, the gas phase component after flash evaporation upwards enters a first hydrogenation reaction zone to carry out hydrodesulfurization and denitrification reaction, and a reaction product is discharged from the top of the reactor; the liquid phase component after flash evaporation enters a second hydrogenation reaction zone downwards to carry out hydrodesulfurization and denitrification reactions, the effluent of the second hydrogenation reaction zone enters a third hydrogenation reaction zone downwards to carry out polycyclic aromatic hydrocarbon hydrogenation saturation reaction, and the product of the third hydrogenation reaction zone is discharged from the bottom of the reactor; wherein, hydrogen enters from the second hydrogenation reaction zone and the third hydrogenation reaction zone of the reactor; the second hydrogenation reaction zone is filled with semi-vulcanized bulk phase hydrofining catalyst; the third hydrogenation reaction zone is filled with a noble metal hydrogenation catalyst; the semi-vulcanized bulk hydrofining catalyst comprises a VIB group metal sulfide, a VIII group metal oxide and Al ₂ O ₃ And an auxiliary agent; based on the weight of the semi-vulcanized bulk hydrofining catalyst, the content of the VIB group metal sulfide is 40% -70%, the content of the VIII group metal oxide is 3% -25%, the content of the auxiliary agent is 3% -15% in terms of oxide, and Al is ₂ O ₃ 24% -54%; the VIB metal sulfide is distributed in the catalyst phase and the surface phase, the weight ratio of the surface phase VIB metal sulfide to the bulk VIB metal sulfide is 2.5:1-7.5:1, and the VIII metal oxide is distributed in the catalyst surface phase; the phase of the VIB metal sulfide is characterized by SEM (scanning electron microscope) energy spectrum and TEM (electron microscope), and the surface phase of the VIB metal sulfide and VIII metal oxide is characterized by XPS (x-ray diffraction)Analyzing energy spectrum; the preparation method of the semi-vulcanized bulk hydrofining catalyst comprises the following steps: (1) Preparing a mixed solution A containing VIB group metal and an aluminum source, and carrying out parallel flow gel forming reaction on the mixed solution A and a precipitator to generate slurry I containing VIB group metal and aluminum precipitate; (2) Pulping and uniformly mixing the slurry I obtained in the step (1) and an auxiliary agent precursor, filtering, washing, drying and forming to obtain a catalyst precursor I; (3) Drying and roasting the catalyst precursor I obtained in the step (2), and then vulcanizing to obtain a catalyst precursor II containing a VIB group metal sulfide; (4) Impregnating the catalyst precursor II obtained in the step (3) with an impregnating solution containing a group VIII metal, and then drying and roasting in an inert atmosphere to obtain the semi-vulcanized type bulk phase hydrofining catalyst.

2. The method according to claim 1, characterized in that: wherein the VIB group metal is Mo and/or W, the VIII group metal is Co and/or Ni, and the auxiliary agent is one or more of B, P, F, mg, zr or Si.

3. The method according to claim 1, characterized in that: the diesel oil raw material is one or more of straight-run diesel oil, catalytic cracking diesel oil, coking diesel oil and boiling bed residual oil hydrogenated diesel oil.

4. The method according to claim 1, characterized in that: the distillation range of the diesel oil raw material is 220-400 ℃, the sulfur content is no more than 15000 mug/g, the nitrogen content is no more than 1000 mug/g, and the cetane number is no less than 35.

5. The method according to claim 1, characterized in that: the flash evaporation zone is used for separating light fraction below 280 ℃ from the raw material, the light fraction enters the first hydrogenation reaction zone as a gas phase component, and the heavy fraction above 280 ℃ enters the second hydrogenation reaction zone as a liquid phase component.

6. The method according to claim 1, characterized in that: the first hydrogenation reaction zoneThe catalyst is used for desulfurizing and denitrifying gas phase components, and Mo-Ni and/or Mo-Co type light distillate oil hydrogenation catalyst is filled in the first hydrogenation reaction zone; the technological conditions of the first hydrogenation reaction zone are as follows: the pressure is 1.0-12.0 MPa, wherein the hydrogen partial pressure accounts for 40% -70% of the total pressure proportion; volume space velocity is 0.1-10.0 h ^-1 The feeding temperature is 150-330 ℃, and the hydrogen oil volume ratio is 10: 1-800: 1.

7. the method according to claim 1, characterized in that: the second hydrogenation reaction zone is used for carrying out deep desulfurization and denitrification reaction on the liquid phase component; the process conditions of the second hydrogenation reaction zone are as follows: the pressure is 1.0-12.0 MPa, wherein the hydrogen partial pressure accounts for 50% -90% of the total pressure proportion; volume space velocity is 0.1-10.0 h ^-1 The reaction temperature is 200-400 ℃, and the hydrogen oil volume ratio is 10: 1-800: 1.

8. the method according to claim 1, characterized in that: in the mixed solution A of the step (1), the weight concentration of the VIB group metal in terms of oxide is 10-100 g/L, and Al is Al ₂ O ₃ The weight concentration is 2-60 g/L.

9. The method according to claim 1, characterized in that: the precipitant in the step (1) is one or more of sodium carbonate, sodium bicarbonate, ammonia water, sodium hydroxide, potassium carbonate or potassium bicarbonate water solution, and the concentration of the precipitant is 0.5 mol/L-3.0 mol/L.

10. The method according to claim 1, characterized in that: in the step (1), the parallel flow gel forming reaction temperature is 30-90 ℃, the pH value is controlled to be 6.0-11.0, and the gel forming time is 0.2-4.0 hours.

11. The method according to claim 1, characterized in that: the auxiliary agent precursor in the step (2) is one or more of boric acid, phosphoric acid, magnesium nitrate, sodium silicate or zirconium nitrate; and after the auxiliary agent precursor and the slurry I are uniformly mixed, controlling the pH value to be 7.0-9.0.

12. The method according to claim 1, characterized in that: drying in the step (3): the drying temperature is 90-200 ℃ and the drying time is 3-6 hours; roasting: the roasting temperature is 400-800 ℃, and the roasting time is 3-6 hours.

13. The method according to claim 1, characterized in that: the vulcanization treatment in the step (3) adopts dry vulcanization or wet vulcanization, wherein the dry vulcanizing agent is hydrogen sulfide, and the wet vulcanizing agent is one or two of carbon disulfide, dimethyl disulfide, methyl sulfide and n-butyl sulfide; the vulcanization pressure is 3.2-6.4 MPa, the vulcanization temperature is 250-400 ℃, and the vulcanization time is 4-12 h.

14. The method according to claim 1, characterized in that: the mass concentration of the impregnating solution of the VIII group metal in the step (4) is 0.1 g/mL-1.0 g/mL, and an equal volume impregnation mode is adopted.

15. The method according to claim 1, characterized in that: the inert atmosphere in the step (4) is N ₂ The method comprises the steps of carrying out a first treatment on the surface of the The drying temperature is 20-90 ℃ and the drying time is 4-16 hours; the roasting temperature is 200-500 ℃, and the roasting time is 2-5 hours.

16. The method according to claim 1, characterized in that: the third hydrogenation reaction zone is used for carrying out a polycyclic aromatic hydrocarbon hydrogenation saturation reaction of heavy fractions, the noble metal hydrogenation catalyst in the third hydrogenation reaction zone comprises a carrier, an active component and an auxiliary agent, wherein the carrier is alumina, the active component is Pt and/or Pd based on the weight of the carrier, and the auxiliary agent is Ni and/or Co; based on the weight of the catalyst, the active component is 0.05 to 5.0 weight percent, the auxiliary agent is 1 to 10 weight percent, and the balance is the carrier; the specific surface area of the catalyst is 300-400m ² Per g, pore volume of 0.4-0.6cm ³ And/g, the crushing strength is 150-250N/cm.

17. The method according to claim 1, characterized in that: the third oneThe process conditions of the hydrogenation reaction zone are as follows: the pressure is 1.0-12.0 MPa, the reaction zone is a pure liquid phase reaction zone, the volume ratio of standard hydrogen to oil is 2-50, and the volume space velocity is 0.1-8.0 h ^-1 The reaction temperature is 150-300 ℃, and the hydrogen-oil volume ratio is 10: 1-800: 1.