CN112745920B

CN112745920B - Hydrocracking method for producing high-octane gasoline

Info

Publication number: CN112745920B
Application number: CN201911043473.9A
Authority: CN
Inventors: 任亮; 严张艳; 刘建伟; 胡志海; 张毓莹; 许双辰; 杨平
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2022-06-28
Anticipated expiration: 2039-10-30
Also published as: CN112745920A

Abstract

The invention relates to a hydrocracking method for producing high-octane gasoline, which comprises the steps of reacting a diesel raw material in a hydrofining reaction zone and a hydrocracking reaction zone I, and separating to obtain a gasoline fraction, a middle fraction and a tail oil fraction. Wherein, the middle fraction returns to the hydrocracking reaction zone I for further conversion, and the tail oil fraction enters the hydrocracking reaction zone II for further conversion. The invention converts polycyclic aromatic hydrocarbon in middle distillate and tail oil distillate to maximum, produces gasoline distillate with high octane number, the RON of the gasoline distillate can reach more than 93, and the loss of total aromatic hydrocarbon is less.

Description

Hydrocracking method for producing high-octane gasoline

Technical Field

The invention relates to a hydrocracking method for producing high-octane gasoline.

Background

With the further upgrading of the quality of domestic diesel oil products and the continuous reduction of the diesel-gasoline ratio, the inferior diesel oil has high content of impurities such as sulfur, nitrogen and the like, high content of aromatic hydrocarbon and low cetane number, and has sharp contradiction with the quality requirement of environmental regulations on the diesel oil. Have not been suitable as clean diesel blending components; the refining and chemical enterprises generally have the problems of clean and efficient production to realize product blending optimization and product value maximization, so that the reasonable utilization of the poor-quality diesel oil becomes a problem of great concern.

The catalytic cracking diesel oil is rich in aromatic hydrocarbon, wherein the content of aromatic hydrocarbon above dicyclic is even up to more than 50%, and the aromatic hydrocarbon components are complex and difficult to separate, so that the catalytic cracking diesel oil is a high-quality resource for preparing high-octane gasoline components and light aromatic hydrocarbon (BTX). Therefore, the catalytic cracking diesel oil hydrogenation conversion is developed to produce high value-added gasoline components and light aromatic hydrocarbons, the value of the product is maximized, and the method has good market application prospects.

CN105085154B discloses a method for increasing the yield of aromatic hydrocarbon raw materials by inferior heavy aromatic hydrocarbons. Mixing raw oil with hydrogen, sequentially carrying out hydrofining and hydrocracking reactions, and fractionating hydrocracking reaction effluent to obtain light fraction, intermediate cut fraction and heavy fraction; the boiling point range of the middle cut fraction is between 100 and 240 ℃, the middle cut fraction, the circulating toluene, the circulating C9+ A fraction and hydrogen are mixed and then enter a middle cut fraction conversion reactor to react, and part or all of heavy fraction is circulated back to a hydrocracking reactor.

CN105295998B discloses a method for producing small molecule aromatic hydrocarbons from diesel oil raw materials. After the poor-quality diesel raw material reacts in the hydrofining reaction zone and the hydrocracking reaction zone I, light gasoline fraction, heavy gasoline fraction, middle fraction and tail oil fraction are obtained through separation and fractionation, the middle fraction enters the hydrocracking reaction zone II for reaction, and the heavy gasoline fraction enters the desulfurization reaction zone for deep desulfurization. The method can effectively convert the poor diesel into high-value products such as benzene, toluene, xylene and the like.

CN106047404B discloses a combined process method for increasing the yield of high-octane gasoline by using poor-quality catalytic cracking diesel. In the method, firstly, selective hydrogenation and denitrogenation reaction of polycyclic aromatic hydrocarbon are carried out on catalytic cracking diesel oil through hydrofining reaction, the refined liquid-phase product and reformed C10+ heavy aromatic hydrocarbon are mixed and enter a lightening reactor filled with a noble metal catalyst for hydrogenation lightening, and dry gas, liquefied gas, gasoline fraction and diesel oil fraction are obtained after separation and fractionation; wherein, the diesel fraction is partially or completely circulated back to the lightening reactor, and finally the purpose of increasing the yield of the high-octane gasoline is realized.

When the prior art is used for processing poor-quality diesel to produce high-octane gasoline or small-molecule aromatic hydrocarbon, although the yield of gasoline fraction is improved to a certain extent, the utilization rate of aromatic hydrocarbon in raw oil is not maximized, and a large amount of aromatic hydrocarbon exists in diesel fraction and is not effectively converted.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a hydrocracking method for producing high-octane gasoline, so as to solve the problems of serious aromatic hydrocarbon loss and non-maximized aromatic hydrocarbon utilization rate in the process of processing poor-quality diesel raw materials to produce high-octane gasoline or small-molecule aromatic hydrocarbon.

The method provided by the invention comprises the following steps:

(1) mixing a diesel raw material with hydrogen-rich gas, and then entering a hydrofining reaction zone to contact and react with a hydrofining catalyst;

(2) the reaction effluent of the hydrofining reaction zone enters a hydrocracking reaction zone I without any intermediate separation device, and is in contact reaction with a first hydrocracking catalyst, and the reaction effluent of the hydrocracking reaction zone I is separated to obtain gas, gasoline fraction, intermediate fraction and tail oil fraction;

(3) the middle fraction returns to the hydrocracking reaction zone I, the tail oil fraction enters the hydrocracking reaction zone II to be in contact reaction with a second hydrocracking catalyst, and reaction effluents of the hydrocracking reaction zone II and the hydrocracking reaction zone I are mixed and then are separated together;

the hydrogen partial pressure of the hydrocracking reaction zone II is 0.1-4.0 MPa higher than that of the hydrocracking reaction zone I;

the second hydrocracking catalyst comprises a carrier and at least one metal component selected from VIII group and at least one metal component selected from VIB group, and the second hydrocracking catalyst contains 1-10 wt% of VIII group metal component and 2-40 wt% of VIB group metal component in terms of oxides based on the second hydrocracking catalyst; the carrier comprises a Y molecular sieve and a matrix, and the carrier is used as a reference, the content of the Y molecular sieve is 30-90 wt%, and the content of the matrix is 10-70 wt%; the strong acid content of the Y molecular sieve accounts for more than 70 percent of the total acid content; the matrix is selected from one or more of alumina, silica and silica-alumina.

In the invention, the boiling point range of the diesel raw material is preferably 165-400 ℃, the total aromatic hydrocarbon content is higher than 60 mass%, and the aromatic hydrocarbon content over dicyclic is higher than 40 mass%. More preferably, the diesel fuel stock has a total aromatic content of more than 65 mass% and a bicyclic or higher aromatic content of more than 45 mass%.

In a preferable case, the diesel oil raw material is selected from one or more of catalytic cracking light cycle oil, catalytic cracking heavy cycle oil, diesel oil fraction of coal direct liquefaction oil and coal tar diesel oil fraction.

In the invention, in a hydrofining reaction zone, a diesel raw material is contacted and reacted with a hydrofining catalyst, sulfides and nitrides are effectively removed after hydrodesulfurization, hydrodenitrogenation and selective hydrogenation of aromatic hydrocarbons, and aromatic hydrocarbons with more than two rings in the poor diesel raw material are hydrogenated and saturated into alkylbenzene monocyclic aromatic hydrocarbons and tetralin monocyclic aromatic hydrocarbons. The invention has no limitation on the hydrofining catalyst, and the preferred hydrofining catalyst has the characteristics of good denitrification performance, excellent hydrogenation saturation performance on aromatic hydrocarbons with more than two rings, high monocyclic aromatic selectivity and the like. The hydrofining catalyst can be the existing commercial hydrofining catalyst or a hydrofining catalyst prepared in a laboratory.

In a preferred aspect, the hydrofinishing catalyst comprises the following components: based on the total weight of the hydrofining catalyst, the content of the VIII group metal component calculated by oxides is 1-30 wt%, and the content of the VIB group metal component calculated by oxides is 5-35 wt%. The VIII group metal component is cobalt and/or nickel, and the VIB group metal component is molybdenum and/or tungsten. The carrier is at least one selected from alumina, alumina-silica and titania.

In a preferred case, the reaction conditions of the hydrofinishing reaction zone are: hydrogen partial pressure of 3.5MPa to 10.0MPa, preferably 4.0MPa to 9.0MPa, reaction temperature of 300 ℃ to 450 ℃, preferably 340 ℃ to 430 ℃, and hydrogen-oil volume ratio of 400 Nm to 2500Nm³/m³Preferably 600 to 1500Nm³/m³Liquid hourly space velocity of 0.2h^-1～6.0h^-1Preferably 0.8h^-1～4.0h^-1。

In the invention, the reaction effluent of the hydrofining reaction zone enters the hydrocracking reaction zone I without any intermediate separation, contacts and reacts with the first hydrocracking catalyst, and carries out selective ring-opening and alkyl side chain cracking reactions on the tetrahydronaphthalene monocyclic aromatic hydrocarbon, alkyl side chain cracking reactions on the alkylbenzene monocyclic aromatic hydrocarbon and the like. In the hydrofining reaction zone and the hydrocracking reaction zone I, the aromatic hydrocarbons with more than two rings in the poor-quality diesel raw material are effectively converted into alkylbenzene monocyclic aromatic hydrocarbons, and part of tetrahydronaphthalene monocyclic aromatic hydrocarbons exist. The first hydrocracking catalyst is not limited in the present invention, and the first hydrocracking catalyst may be an existing commercial hydrocracking catalyst or a laboratory-prepared hydrocracking catalyst.

In a preferred case, the first hydrocracking catalyst comprises a carrier and at least one metal component selected from VIII group and at least one metal component selected from VIB group, the carrier comprises a molecular sieve and a matrix, and the molecular sieve is selected from one or more of Y, ZSM-5 and Beta. The first hydrocracking catalyst contains 1-10 wt% of a group VIII metal component, preferably 2-8 wt% of the first hydrocracking catalyst calculated by oxides based on the first hydrocracking catalyst; 5 to 50 wt% of a group VIB metal component, preferably 10 to 35 wt%.

In a preferred case, the reaction conditions of the hydrocracking reaction zone I are: the hydrogen partial pressure is 4.0-12.0 MPa, preferably 5.0-10.0 MPa, the reaction temperature is 300-450 ℃, preferably 380-450 ℃, and the volume ratio of hydrogen to oil is 400-2500 Nm³/m³Preferably 700 to 2000Nm³/m³The liquid hourly space velocity is 0.2-5.0 h^-1Preferably 0.8 to 5.0 hours^-1。

In the invention, the reaction effluent of the hydrocracking reaction zone I is separated by a separation system and a fractionation system to obtain gasoline fraction, middle fraction and tail oil fraction.

In a preferable case, the cutting point of the middle distillate and the tail oil distillate ranges from 240 ℃ to 300 ℃; the aromatic hydrocarbon content in the middle distillate is higher than 60 wt%, and the monocyclic aromatic hydrocarbons of alkylbenzene and tetrahydronaphthalene are higher than 55 wt%. More preferably, the nitrogen content in the middle distillate is 20 μ g/g or less. The middle fraction is rich in C9 and above alkylbenzene and tetrahydronaphthalene monocyclic aromatics, and the middle fraction is returned to the inlet of a hydrocracking reaction zone I to further carry out ring opening and side chain breaking reactions so as to convert C9 and above monocyclic aromatics into micromolecular aromatics.

Preferably, the distillation range initial boiling point of the tail oil fraction is more than 240 ℃, the carbon number is higher than C15, the aromatic hydrocarbon content in the tail oil fraction is higher than 55 wt%, the single ring aromatic hydrocarbon content of alkylbenzene and tetralin is higher than 20 wt%, the double ring aromatic hydrocarbon content is higher than 30 wt%, and the aromatic hydrocarbon content of tricyclic and higher is not higher than 5 wt%. And the tail oil fraction enters a hydrocracking reaction zone II and is in contact reaction with a corresponding second hydrocracking catalyst, so that double-ring and above aromatic hydrocarbons in the tail oil fraction can be selectively hydrogenated and saturated into single-ring aromatic hydrocarbons, and then small-molecule aromatic hydrocarbons are obtained through ring opening and side chain breaking, so that the aim of increasing the yield of high-octane gasoline is fulfilled.

In one preferred embodiment of the invention, at least 20 wt% of the tail oil fraction is passed to hydrocracking reaction zone II, with the remaining tail oil fraction being used as a clean diesel blending component.

In a preferred case, the reaction conditions of the hydrocracking reaction zone II are: the hydrogen partial pressure is 4.0-12.0 MPa, and the hydrogen partial pressure of the hydrocracking reaction zone II is 0.1-4.0 MPa higher than that of the hydrocracking reaction zone I; the reaction temperature is 300-450 ℃, preferably 370-450 ℃; the volume ratio of hydrogen to oil is 400-2200 Nm³/m³Preferably 600 to 1800Nm ³/m³(ii) a Liquid hourly volume space velocity of 0.2h^-1～5.0h^-1Preferably 1.0h^-1～3.0h^-1。

In the invention, the reaction product of the hydrocracking reaction zone II and the reaction product of the hydrocracking reaction zone I are mixed and then enter a separation system and a fractionation system together, and gas, gasoline fraction, middle fraction and tail oil fraction are obtained through separation. The distillation range of the obtained gasoline fraction is 50-205 ℃, the octane number content is high, and the gasoline fraction can be a blending component of high-octane number gasoline.

In the invention, the second hydrocracking catalyst comprises a carrier and at least one metal component selected from VIII group and at least one metal component selected from VIB group, and the second hydrocracking catalyst contains 1-10 wt% of VIII group metal component and 2-40 wt% of VIB group metal component in terms of oxides based on the second hydrocracking catalyst; the carrier comprises a Y molecular sieve and a matrix, and the carrier is used as a reference, the content of the Y molecular sieve is 30-90 wt%, and the content of the matrix is 10-70 wt%; the strong acid content of the Y molecular sieve accounts for more than 70 percent of the total acid content; the matrix is selected from one or more of alumina, silica and silica-alumina.

In a preferred aspect, the Y molecular sieve has a micropore specific surface area of 650m ²A value of at least 700 m/g, more preferably 700m²More than g; the proportion of the mesoporous volume of the Y molecular sieve to the total pore volume is 30 to 50%, and more preferably 33 to 45%.

Preferably, the unit cell constant of the Y molecular sieve is 2.415-2.440 nm; the proportion of the peak area of a resonance signal with the chemical shift of 0 +/-2 ppm in the 27Al MAS NMR spectrum of the Y molecular sieve to the total peak area is not more than 4 percent. Further preferably, the unit cell constant of the Y molecular sieve is 2.422-2.438 nm; the proportion of the peak area of a resonance signal with the chemical shift of 0 +/-2 ppm in the 27Al MAS NMR spectrum of the Y molecular sieve to the total peak area is not more than 3 percent.

Further preferably, the strong acid amount of the Y molecular sieve is 75% or more of the total acid amount.

The strong acid of the Y molecular sieve in the invention is NH₃Temperature programmed desorption (NH)₃Acid with desorption temperature higher than 320 ℃ in the TPD) curve, the ratio of the strong acid amount to the total acid amount is NH₃The desorption temperature in the TPD result is greater than the ratio of the strong acid content to the total acid content at 320 ℃.

Preferably, the content of the Y molecular sieve is 45-80 wt% and the content of the matrix is 20-55 wt% based on the carrier.

In a preferable case, the Y molecular sieve in the second hydrocracking catalyst is prepared by multiple dealumination and three times of water roasting, aluminum vacancies formed in the dealumination process can be filled with silicon as much as possible in the water roasting process, and the generated non-framework aluminum is gradually stripped through multiple dealumination, and the three times of hydrothermal roasting and the multiple dealumination complement each other, so that the integrity of crystals is favorably maintained, and more strong acid centers are reserved.

Therefore, the Y molecular sieve in the second hydrocracking catalyst preferably has high silica-alumina ratio, less non-framework aluminum, high strong acid center ratio, large specific surface area, rich secondary pores, higher reaction activity in hydrocarbon cracking reactions such as hydrocracking and the like, less secondary reaction, good ring-opening reaction selectivity, good acid stability and slow inactivation.

The process of converting polycyclic aromatic hydrocarbon into light aromatic hydrocarbon by hydrocracking mainly comprises the ideal reactions of selective hydrogenation saturation of polycyclic aromatic hydrocarbon, ring opening of naphthenic rings, side chain breaking of alkyl aromatic hydrocarbon and the like. The inventor of the invention researches and discovers that the secondary pores of the acidic components in the hydrocracking catalyst are increased in a certain range, the surface area of the molecular sieve is increased, the smoothness of the pore channels is improved, the accessibility of reaction molecules on an acidic active center is favorably improved, and the ring-opening and cracking activity of the reaction molecules is further improved; meanwhile, the surface property and the pore structure of the molecular sieve can also adjust the dispersion of metal components and the structure of an active phase, so that the hydrogenation performance of the hydrocracking catalyst is optimized, and the synergistic effect of a hydrogenation center and an acid center on the hydrocracking catalyst is enhanced, thereby improving the selectivity of selective hydrogenation saturation, selective ring opening and cracking reaction of the polycyclic aromatic hydrocarbon. That is to say, the preferable second hydrocracking catalyst has the characteristics of high polycyclic aromatic hydrocarbon hydrogenation saturation activity, strong naphthene ring opening performance and high monocyclic aromatic hydrocarbon retention degree, effectively improves the octane number in gasoline fraction, and has few light products and low chemical hydrogen consumption.

The invention has the characteristics that:

(1) the invention adopts the process of a hydrofining-hydrocracking reaction zone I-hydrocracking reaction zone II and a method of returning middle distillate to the hydrocracking reaction zone I and leading tail oil distillate to enter the hydrocracking reaction zone II, and realizes the purpose of increasing the yield of high-octane gasoline distillate by combining different processing means on different distillates, the RON of the gasoline distillate obtained by the invention can reach more than 93, and the loss of total aromatic hydrocarbon is less.

(2) According to the second hydrocracking catalyst, the molecular sieve is modified, and the Y molecular sieve with high silicon-aluminum ratio, less non-framework aluminum, large specific surface area, rich secondary pores and high strong acid center ratio is used, so that the ring-opening and cracking performance of the second hydrocracking catalyst is improved, and the synergy and matching of the hydrogenation function and the acidic function are enhanced, so that the second hydrocracking catalyst has the characteristics of high polycyclic aromatic hydrocarbon hydrogenation saturation activity, strong naphthenic ring opening performance and high monocyclic aromatic hydrocarbon retention.

The first hydrocracking catalyst has excellent functions of selective ring opening and alkyl side chain breaking, and has good selectivity on reactions such as monocyclic aromatic alkyl side chain breaking, tetrahydronaphthalene selective ring opening and side chain breaking; the second hydrocracking catalyst has excellent selective hydrogenation activity and selective ring-opening cracking performance. The invention fully exerts the synergistic function of two catalysts of the hydrocracking reaction zone I and the hydrocracking reaction zone II, maximizes the utilization of aromatic hydrocarbons in the middle distillate and the tail oil distillate, and finally obtains the high-yield and high-octane gasoline distillate with low hydrogen consumption.

Drawings

Fig. 1 is a schematic diagram of a hydrocracking process for producing high-octane gasoline according to the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings, but the invention is not limited thereby.

Fig. 1 is a schematic diagram of a hydrocracking process for producing high-octane gasoline according to the present invention, as shown in fig. 1:

the diesel oil raw material and hydrogen from the pipeline 19 enter the hydrofining reactor 1 to contact with the hydrofining catalyst for reaction, and the reaction effluent from the hydrofining reactor 1 and the middle distillate from the pipeline 7 are mixed and enter the first hydrocracking reactor 2 to contact with the first hydrocracking catalyst for reaction. The tail oil fraction from the pipeline 8 enters the second hydrocracking reactor 3 to contact with a second hydrocracking catalyst for reaction. The reaction effluent of the first hydrocracking reactor 2 and the reaction effluent of the second hydrocracking reactor 3 enter a high-pressure separator 4 through a pipeline 10 to be subjected to gas-liquid separation to obtain hydrogen-rich gas and a liquid product, the hydrogen-rich gas is extracted through a pipeline 11 and then recycled (a hydrogen circulating system is omitted here), the liquid product enters a low-pressure separator 5 through a pipeline 12, low-fraction gas obtained by separation is extracted through a pipeline 13, the liquid product obtained by separation enters a fractionation system 6 through a pipeline 14, dry gas and liquefied gas obtained by fractionation are extracted through a pipeline 15, gasoline fraction obtained by fractionation is extracted through a pipeline 16, middle fraction obtained by fractionation is extracted through a pipeline 17, and tail oil fraction obtained by fractionation is extracted through a pipeline 18.

The invention is further illustrated by the following examples, without any intention to limit the invention thereto.

In the examples, the commercial designation of the hydrorefining catalyst A was RN-411 and the commercial designation of the first hydrocracking catalyst B was RHC-100.

The second hydrocracking catalyst C was prepared as follows:

firstly, the Y molecular sieve in the second hydrocracking catalyst C was prepared by multiple dealumination and triple water roasting:

(1) exchanging NaY zeolite serving as a raw material with an ammonium chloride solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium chloride: water 1: 0.7: 10, exchange at 85 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 600 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): citric acid: sulfuric acid: water 1: 0.15: 0.05: and 8, adding water into the molecular sieve, pulping, heating, adding 20% sulfuric acid at a constant speed at 70 ℃ under stirring, controlling the dropping time for 30min, adding 20% citric acid aqueous solution, controlling the dropping time for 20min, continuously stirring at 70 ℃ for 1h after the addition is finished, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 600 ℃, and roasting for 2 hours in the atmosphere of 100% of water vapor.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: ammonium sulfate: water 1: 0.06: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, stirring uniformly, slowly dropwise adding hydrochloric acid with the concentration of 15%, controlling the dropwise adding time to be 1h, heating to 60 ℃, treating for 40min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(6) And (5) carrying out third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 550 ℃, and roasting for 3 hours in the atmosphere of 100% water vapor.

(7) And (3) mixing the molecular sieve obtained in the step (6) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: oxalic acid: ammonium sulfate: water 1: 0.05: 0.19: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly dripping hydrochloric acid with the concentration of 10%, controlling the dripping time for 40min, adding oxalic acid, heating, treating at 70 ℃ for 60min, filtering, and washing with deionized water.

(8) Sieving the molecular sieve obtained in the step (7) according to a molecular sieve; ammonium chloride: fluosilicic acid, hydrochloric acid: adding water into a molecular sieve for pulping, adding ammonium chloride, slowly dropwise adding 30% fluosilicic acid and 20% hydrochloric acid at the same time, controlling the dropwise adding time for 60min, heating, treating at 60 ℃ for 50min, filtering, and washing with deionized water to obtain the molecular sieve Y, wherein the H2O is the ratio of 1:0.5:0.03:0.008: 10. The obtained molecular sieve Y has a cell constant of 2.435nm, a mesoporous proportion of 41%, a strong acid proportion of 81%, and a micropore specific surface area of 713m ²The ratio of the peak area of a resonance signal with a chemical shift of 0 +/-2 ppm in a 27Al MAS NMR spectrum of the Y molecular sieve to the total peak area is 2.3 percent.

Weighing 128.6 g of pseudo-boehmite (catalyst Chang Ling division) with dry basis of 70% and 129.4 g of the obtained molecular sieve Y with dry basis of 85%, uniformly mixing, extruding on a strip extruder into a three-blade shape with the circumscribed circle diameter of 1.6 mm, drying at 120 ℃ for 3 hours, and roasting at 600 ℃ for 4 hours to obtain the catalyst carrier.

Taking 100 g of carrier, and using 85 ml of carrier respectively containing MoO₃176.5 g/l, NiO 35.3 g/l, P₂O₅And (3) soaking the mixed solution of 35.3 g/L of molybdenum trioxide, basic nickel carbonate and phosphoric acid for 3 hours, drying the mixed solution at the temperature of 120 ℃ for 2 hours, and roasting the dried mixed solution at the temperature of 450 ℃ for 3 hours to obtain a second hydrocracking catalyst C.

The second hydrocracking catalyst C had a composition comprising, in terms of oxide, 15% by weight of molybdenum, 3% by weight of nickel and 3% by weight of phosphorus, based on the second hydrocracking catalyst C; based on the carrier, the content of the Y molecular sieve was 43.5 wt%, and the content of the alumina was 35.6 wt%.

The feedstocks E and F used in the examples were from a catalytic cracker and their properties are given in Table 1.

As can be seen from Table 1, the total aromatic content of the raw oil E, F is higher than 80%, the aromatic content above bicyclic ring reaches more than 50%, the raw oil E has low sulfur and high nitrogen, and the raw oil F has high sulfur and low nitrogen, and are typical poor quality catalytic cracking diesel oil raw materials.

The BTX yields in the examples and comparative examples refer to:

yield of BTX gasoline fraction x BTX content in gasoline fraction x 100%

Comparative example 1

The raw oil E and hydrogen enter a hydrofining reaction zone together, contact and react with a hydrofining catalyst A, and the reaction effluent and middle distillate oil in the hydrofining reaction zone enter a hydrocracking reaction zone I, contact and react with a first hydrocracking catalyst B. And the reaction effluent of the hydrocracking reaction zone I sequentially enters separation facilities such as a high-pressure separator, a low-pressure separator, a fractionating tower and the like, and is subjected to cooling, gas-liquid separation and fractionation to obtain dry gas, liquefied gas, gasoline fraction and diesel fraction. The reaction conditions are shown in Table 2, and the product yields and properties are shown in Table 3.

As can be seen from Table 3, the yield of the gasoline fraction was 45.5% by weight, the sulfur content was 6.8. mu.g/g, the yield of BTX was 14.5%, and the research octane number was 93.8.

Comparative example 2

Raw oil E and hydrogen enter a hydrofining reaction zone together, contact and react with a hydrofining catalyst A, and the reaction effluent and middle distillate of the hydrofining reaction zone enter a hydrocracking reaction zone I, contact and react with a first hydrocracking catalyst B. And the reaction effluent of the hydrocracking reaction zone I sequentially enters separation facilities such as a high-pressure separator I, a low-pressure separator, a fractionating tower and the like, and is subjected to cooling, gas-liquid separation and fractionation to obtain dry gas, liquefied gas, gasoline fraction, middle fraction and tail oil fraction. Wherein, the middle distillate oil is completely circulated to the hydrocracking reaction area I to continue the cracking conversion, and the tail oil fraction enters the hydrocracking reaction area II to contact and react with a hydrocracking catalyst B. And the reaction effluent of the hydrocracking reaction zone II enters a high-pressure separator II, and the obtained liquid returns to a low-pressure separator and a fractionation system. The reaction conditions are shown in Table 2, and the product yields and properties are shown in Table 3.

As can be seen from Table 3, the yield of the gasoline fraction was 57.5% by weight, the sulfur content was 3.6. mu.g/g, the yield of BTX was 18.5%, and the research octane number was 93.2.

Example 1

The raw oil E and hydrogen enter a hydrofining reaction zone together and are in contact reaction with a hydrofining catalyst A, and the reaction effluent of the hydrofining reaction zone and middle distillate enter a hydrocracking reaction zone I together and are in contact reaction with a first hydrocracking catalyst B. And the reaction effluent of the hydrocracking reaction zone I sequentially enters separation facilities such as a high-pressure separator I, a low-pressure separator and a fractionating tower, and is subjected to cooling, gas-liquid separation and fractionation to obtain dry gas, liquefied gas, gasoline fraction, middle fraction and tail oil fraction, wherein the cutting point of the middle fraction and the tail oil fraction is 280 ℃. The aromatic hydrocarbon content in the middle distillate is 78 wt%, and the monocyclic aromatic hydrocarbons of alkylbenzene and tetrahydronaphthalene are 68 wt%; wherein, the middle fraction is completely circulated to the hydrocracking reaction zone I to continue the cracking conversion, and the tail oil fraction enters the hydrocracking reaction zone II to contact and react with a second hydrocracking catalyst C. And the reaction effluent of the hydrocracking reaction zone II enters a high-pressure separator II, and the obtained liquid returns to a low-pressure separator and a fractionation system. The reaction conditions are shown in Table 2, and the product yields and properties are shown in Table 3.

As can be seen from Table 3, the yield of the gasoline fraction was 87.7% by weight, the sulfur content was 4.5. mu.g/g, the BTX yield was 30.3%, and the research octane number was 95.5.

Example 2

Raw oil E and hydrogen enter a hydrofining reaction zone together to contact and react with a hydrofining catalyst A, and a reaction effluent and a middle fraction in the hydrofining reaction zone enter a hydrocracking reaction zone I to contact and react with a first hydrocracking catalyst B. And the reaction effluent of the hydrocracking reaction zone I sequentially enters separation facilities such as a high-pressure separator I, a low-pressure separator, a fractionating tower and the like, and is subjected to cooling, gas-liquid separation and fractionation to obtain dry gas, liquefied gas, gasoline fractions, middle fractions and tail oil fractions, wherein the cutting point of the middle fractions and the tail oil fractions is 290 ℃, the aromatic hydrocarbon content in the middle fractions is 76 weight percent, and the alkylbenzene and tetrahydronaphthalene monocyclic aromatic hydrocarbon content is 68 weight percent. Wherein, the middle distillate oil is completely circulated to the hydrocracking reaction area I for continuous cracking conversion, and 50 weight percent of tail oil fraction enters the hydrocracking reaction area II for contact reaction with a second hydrocracking catalyst C. And (3) enabling the reaction effluent of the hydrocracking reaction zone II to enter a high-pressure separator II, returning the obtained liquid to a low-pressure separator and a fractionation system, and taking the rest tail oil fraction as a low-sulfur diesel blending component. The reaction conditions are shown in Table 2, and the product yields and properties are shown in Table 3.

As can be seen from Table 3, the yield of the gasoline fraction was 70.5% by weight, the sulfur content was 2.3. mu.g/g, the BTX yield was 31.0%, and the research octane number was 94.1.

Example 3

The raw oil F and hydrogen enter a hydrofining reaction zone together to be in contact reaction with a hydrofining catalyst A, and a reaction effluent and a middle fraction in the hydrofining reaction zone enter a hydrocracking reaction zone I to be in contact reaction with a first hydrocracking catalyst B. The reaction effluent of the hydrocracking reaction zone I sequentially enters separation facilities such as a high-pressure separator I, a low-pressure separator and a fractionating tower, and is subjected to cooling, gas-liquid separation and fractionation to obtain dry gas, liquefied gas, gasoline fraction, middle fraction and tail oil fraction, wherein the cutting point of the middle fraction and the tail oil fraction is 300 ℃; the aromatic content in the tail oil fraction was 64 wt%, the alkylbenzene and tetralin monocyclic aromatic contents were 25 wt%, and the bicyclic aromatic content was 37 wt%. Wherein, the middle distillate oil is completely circulated to the hydrocracking reaction area I for continuous cracking conversion, and the tail oil fraction enters the hydrocracking reaction area II for contact reaction with a second hydrocracking catalyst C. And (3) enabling the reaction effluent of the hydrocracking reaction zone II to enter a high-pressure separator II, and returning the obtained liquid to a low-pressure separator and a fractionation system. The reaction conditions are shown in Table 2, and the product yields and properties are shown in Table 3.

As can be seen from Table 3, the yield of the gasoline fraction was 88.2% by weight, the sulfur content was 2.9. mu.g/g, the BTX yield was 34.9%, and the research octane number was 93.2.

TABLE 1

TABLE 2

TABLE 3

	Comparative example 1	Comparative example 2	Example 1	Example 2	Example 3
						Yield of dry gas and liquefied gas, weight%	9.8	7.5	13.3	8.0	14.6
Yield of gasoline fraction,% by weight	45.5	57.5	87.7	70.5	88.2
						Properties of gasoline fraction
Density (20 ℃ C.)/(g. cm)^-3)	0.7996	0.801	0.805	0.802	0.816
						Sulfur content, μ g^-1	6.8	3.6	4.5	2.3	2.9
BTX yield, wt.%	14.5	18.5	30.3	31.0	34.9
						Research octane number	93.8	93.2	95.5	94.1	93.2
Motor octane number	82.6	82.2	84.0	83.8	82.9
						Distillation range (ASTM-D86), DEG C
IBP	85	85	85	85	84
						10％	115	113	114	118	113
50％	140	142	144	148	145
						90％	186	184	183	185	182
FBP	205	205	205	205	205

Claims

1. A hydrocracking process for producing a high octane gasoline comprising:

(2) the reaction effluent of the hydrofining reaction zone enters a hydrocracking reaction zone I without any intermediate separation device, and is in contact reaction with a first hydrocracking catalyst, the reaction effluent of the hydrocracking reaction zone I is separated to obtain gas, gasoline fraction, middle fraction and tail oil fraction, the cutting point range of the middle fraction and the tail oil fraction is 240-300 ℃, the content of aromatic hydrocarbon in the tail oil fraction is higher than 55 wt%, the content of alkylbenzene monocyclic aromatic hydrocarbon and tetrahydronaphthalene monocyclic aromatic hydrocarbon is higher than 20 wt%, and the content of bicyclic aromatic hydrocarbon is higher than 30 wt%;

(3) The middle fraction returns to the hydrocracking reaction zone I, the tail oil fraction enters the hydrocracking reaction zone II to be in contact reaction with a second hydrocracking catalyst, and reaction effluents of the hydrocracking reaction zone II and the hydrocracking reaction zone I are mixed and then separated together;

the hydrogen partial pressure of the hydrocracking reaction zone II is 0.1MPa to 4.0MPa higher than that of the hydrocracking reaction zone I;

the second hydrocracking catalyst comprises a carrier and at least one metal component selected from VIII group and at least one metal component selected from VIB group, and the second hydrocracking catalyst contains 1-10 wt% of VIII group metal component and 2-40 wt% of VIB group metal component in terms of oxides based on the second hydrocracking catalyst; the carrier comprises a Y molecular sieve and a matrix, and the carrier is used as a reference, the content of the Y molecular sieve is 30-90 wt%, and the content of the matrix is 10-70 wt%; the strong acid content of the Y molecular sieve accounts for more than 70 percent of the total acid content, and the micropore specific surface area of the Y molecular sieve is 650m²More than g, the proportion of the mesoporous volume of the Y molecular sieve in the total pore volume is 30-50%; the matrix is selected from one or more of alumina, silica and silica-alumina.

2. The method according to claim 1, wherein the boiling point range of the diesel fuel raw material is 165-400 ℃, the total aromatic hydrocarbon content is higher than 60 mass%, and the aromatic hydrocarbon content over dicyclic is higher than 40 mass%.

3. A process according to claim 2, characterized in that the total aromatics content of the diesel feedstock is higher than 65 mass%, and the aromatics content over bicyclic rings is higher than 45 mass%.

4. The process according to claim 1, characterized in that the middle distillate contains aromatic hydrocarbons in an amount higher than 60% by weight and the alkylbenzene and tetralin monocyclic aromatic hydrocarbons in an amount higher than 55% by weight.

5. The process of claim 1 wherein at least 20 wt% of the tail oil fraction is passed to hydrocracking reaction zone II and the remaining tail oil fraction is used as a clean diesel blending component.

6. The process of claim 1, wherein the reaction conditions in the hydrofinishing reaction zone are: hydrogen partial pressure of 3.5-10.0 MPa, reaction temperature of 300-450 ℃, hydrogen-oil volume ratio of 400-2500 Nm³/m³The volume airspeed is 0.2-6.0 h^-1。

7. The process of claim 1, wherein the hydrocracking reaction zone I comprises the following reaction conditions: the hydrogen partial pressure is 4.0-12.0 MPa, the reaction temperature is 300-450 ℃, and the volume ratio of hydrogen to oil is 400-2500 Nm ³/m³The liquid hourly volume space velocity is 0.2-5.0 h^-1；

The reaction conditions of the hydrocracking reaction zone II are as follows: the hydrogen partial pressure is 4.0MPa to 12.0MPa, the reaction temperature is 300 ℃ to 450 ℃, and the volume ratio of hydrogen to oil is 400 Nm to 2200Nm³/m³Liquid hourly volume space velocity of 0.2h^-1～5.0h^-1。

8. The method of claim 1, wherein the Y molecular sieve has a specific surface area of micropores of 700m²More than g; the proportion of the mesoporous volume of the Y molecular sieve in the total pore volume is 33-45%.

9. The method of claim 1, wherein the Y molecular sieve has a unit cell constant of 2.415 to 2.440 nm; the proportion of the peak area of a resonance signal with a chemical shift of 0 +/-2 ppm in a 27Al MAS NMR spectrum of the Y molecular sieve to the total peak area is not more than 4%.

10. The method of claim 9, wherein the unit cell constant of the Y molecular sieve is 2.422-2.438 nm; the proportion of the peak area of a resonance signal with the chemical shift of 0 +/-2 ppm in the 27Al MAS NMR spectrum of the Y molecular sieve to the total peak area is not more than 3 percent.

11. The method of claim 1, wherein the Y molecular sieve has a strong acid content of 75% or more of the total acid content.

12. The process of claim 1 wherein the second hydrocracking catalyst comprises from 1 to 6 wt.% of a group VIII metal component and from 5 to 25 wt.% of a group VIB metal component, calculated as oxides, based on the second hydrocracking catalyst.

13. The method of claim 1, wherein the Y molecular sieve is present in an amount of 45 to 80 wt% and the matrix is present in an amount of 20 to 55 wt% based on the support.