阅读说明：本技术 一种制备轻质芳烃的方法和系统 (Method and system for preparing light aromatic hydrocarbon ) 是由 郑均林 孔德金 宋奇 姜向东 侯敏 祁晓岚 于 2019-09-30 设计创作，主要内容包括：本发明涉及一种生产高品质轻质芳烃的加氢裂化方法及系统。主要解决以往技术以芳烃为目标产品时芳烃纯度不高的问题。本发明通过将催化柴油物流经过加氢精制、分离杂质、深度脱氮后进行加氢裂化反应。反应后分离得到包括轻烃、富含轻质芳烃的重石脑油和重质尾油在内的馏分。可用于从催化柴油生产含高品质轻质芳烃的重石脑油,解决了催化柴油的加氢裂化产物芳烃纯度不高的问题,取得了较好的技术效果。(The invention relates to a hydrocracking method and a hydrocracking system for producing high-quality light aromatic hydrocarbons. Mainly solves the problem of low aromatic hydrocarbon purity when the aromatic hydrocarbon is taken as a target product in the prior art. The invention carries out hydrocracking reaction after hydrorefining, impurity separation and deep denitrification on the catalytic diesel material flow. After the reaction, fractions including light hydrocarbon, heavy naphtha rich in light aromatic hydrocarbon and heavy tail oil are obtained by separation. Can be used for producing heavy naphtha containing high-quality light aromatic hydrocarbon from catalytic diesel oil, solves the problem of low purity of aromatic hydrocarbon of hydrocracking products of the catalytic diesel oil, and obtains better technical effect.)

1. A method for producing light aromatic hydrocarbons, comprising the steps of:

1) contacting catalytic diesel with a hydrofining catalyst under a hydrogen condition to obtain a first material flow;

2) contacting a liquid phase material flow obtained after the first material flow is separated from impurities with a denitrification catalyst under the hydrogen condition to obtain a second material flow;

3) contacting the second stream with a hydrocracking catalyst under hydrogen conditions to obtain a third stream;

4) and separating the third stream to obtain fractions including dry gas, light hydrocarbon, heavy naphtha rich in light aromatics and heavy tail oil.

2. The method of claim 1, wherein:

said step 2) of separating impurities from the first stream comprises the steps of subjecting said first stream to gas-liquid separation and stripping.

3. The method of claim 1, wherein:

the denitrification catalyst in the step 2) comprises the following components in parts by weight: a) 1-30 parts of beta-nickel molybdate; b)0.5-10 parts of silicon dioxide; c) 60-98.5 parts of alumina.

4. The method of claim 1, wherein:

the hydrocracking catalyst in the step 3) comprises the following components in parts by weight: a) 5-80 parts of solid acid zeolite with a space index less than 18; b)0.05 to 8 parts of a group VIII metal; c) 3-25 parts of a group VIB metal oxide; d) 15-90 parts of a binder.

5. The method according to claim 1, wherein the denitrification reaction conditions of the step 2) include:

hydrogen oil bodyThe product ratio is 50-1000 Nm³/m³Preferably 100 to 800Nm³/m³More preferably 150 to 500Nm³/m³(ii) a And/or the presence of a gas in the gas,

the inlet temperature of the reactor is 200-; and/or the presence of a gas in the gas,

the hydrogen partial pressure is 0.5-10 MPa, preferably 1-8 MPa, and more preferably 3-6 MPa; and/or the presence of a gas in the gas,

the airspeed is 0.2-4.0 hours^-1Preferably 0.5 to 3 hours^-1More preferably 0.6 to 2 hours^-1。

6. The method of claim 1, wherein:

the step 4) of separating the third stream comprises gas-liquid separation and fractionation.

7. The method of claim 1, wherein:

the second stream has a nitrogen content of less than 5ppm, preferably less than 2 ppm.

8. The method of claim 1, wherein:

in the heavy naphtha fraction obtained in the step 4): the aromatic content of the 136-144 ℃ cut fraction is more than 98 percent.

9. A system for producing light aromatic hydrocarbons according to any one of claims 1 to 8, comprising:

a first device; configured to receive the catalytic diesel and to emit the first stream;

a second device; configured to receive said first stream separated from impurities in a liquid phase stream and to discharge said second stream;

a third device; configured to receive the second stream and to discharge the third stream;

a first separation zone; configured to receive the third stream; discharging fractions including the dry gas, light hydrocarbons, heavy naphtha rich in light aromatics, and heavy tail oil.

10. The system of claim 9, wherein:

the reactor in the first device is a fixed bed reaction system, a hydrofining catalyst is filled in the reactor, and a circulating hydrogen system is preferably configured; and/or the presence of a gas in the gas,

the second device is a catalytic denitrification device, and the reactor of the second device is a fixed bed reaction system filled with the denitrification catalyst; and/or the presence of a gas in the gas,

the reactor in the third device is a fixed bed reaction system, is filled with a hydrocracking catalyst, and is preferably provided with a circulating hydrogen system.

11. The system of claim 9, wherein:

the first separation zone comprises a gas-liquid separator and a fractionation system which are connected in sequence and is used for separating and obtaining fractions including the dry gas, light hydrocarbon, heavy naphtha rich in light aromatic hydrocarbon and heavy tail oil in sequence.

12. The system of claim 9, wherein:

a second separation area is arranged between the first device and the second device; the second separation zone is configured to receive the first stream and discharge a stream comprising a gas phase, a hydrogen sulfide and ammonia stream, and a liquid phase stream after separation of impurities.

13. The system of claim 12, wherein:

the second separation zone comprises a gas-liquid separator and a stripping apparatus.

Technical Field

The invention relates to the technical field of hydrocracking, in particular to a hydrocracking method and a hydrocracking system for producing high-quality light aromatic hydrocarbon from catalytic diesel oil.

Background

In petrochemical plants, aromatics complexes are typically targeted at para-xylene (co-production of ortho-xylene) to provide feedstock for downstream PTA (xylene to purified terephthalic acid) plants. Except for xylene in catalytic reformate and pyrolysis gasoline, aromatic hydrocarbon raw materials such as toluene, C9/C10 aromatic hydrocarbon and the like are subjected to disproportionation and transalkylation reaction under the action of a molecular sieve catalyst to generate mixed xylene and benzene. The non-aromatics content of the C9/C10 heavy aromatics entering the disproportionation and transalkylation unit is desirably less than 0.5 wt%. The mixed xylene is subjected to crystallization separation or adsorption separation to produce the paraxylene. The mixed xylene entering the separation device is also required to have a lower non-aromatic content to ensure the concentration of paraxylene in the raw material and improve the separation efficiency.

Both ethylene plants and aromatics complex use naphtha as a feedstock, and the limited naphtha resources are still required to meet the rapidly growing demand for motor gasoline. The dependence degree on raw material naphtha is reduced, the aromatic hydrocarbon raw material resources are expanded, and the method is an important subject for developing petrochemical industry at present. The sulfur content of catalytic diesel oil (LCO) is 0.2-1.5 wt%, the nitrogen content is 100-1500 ppm, the cetane number is only 15-25, the ignition performance is poor, and the technical economy of processing the catalytic diesel oil into the vehicle diesel oil is poor. The total aromatic hydrocarbon content is up to more than 70 wt%, wherein naphthalene series bicyclic aromatic hydrocarbon accounts for about 70 wt%, monocyclic aromatic hydrocarbon and tricyclic aromatic hydrocarbon respectively account for about 15 wt%, and the others are alkane, cyclane, alkene and the like, and are an aromatic hydrocarbon resource library with huge energy.

The annual processing capacity of a catalytic cracking (FCC) unit in China is close to 2 hundred million tons, and the annual production capacity of LCO exceeds 4000 million tons. With the shift in market demand for diesel going softer, the production of diesel from LCO is increasingly uneconomical. In the light oil type hydrocracking, catalytic diesel oil is subjected to hydrofining and then subjected to hydrocracking reaction to obtain a heavy material or a gasoline fraction of naphtha fraction, and the problem of low yield of aromatic hydrocarbon in the obtained naphtha exists in the process. If the naphtha fraction is used for reforming an aromatic feedstock, the naphthenes and paraffins formed after the supersaturation are also converted to aromatics in the reformer, which is not an economical route. The light oil hydrocracking process, as described in the CN101684415A patent, does not directly produce aromatics, and the heavy naphtha has an aromatics potential of only 57% at the maximum.

Chinese patent CN101724454A and the literature (Catalysis Today, 271 (2016)) 149-. Wherein the aromatic content of 65-210 deg.C fraction is 62.01%, due to C₈、C₉And C₁₀The fractions all contain higher levels of non-aromatics and cannot be integrated with the overall flow path of existing aromatics complexes. In addition, about 40 wt% of low-quality diesel oil is produced, and the utilization efficiency of raw materials is low.

Chinese patent CN110180581A describes a catalyst and its use in C₁₁ ⁺Application of the heavy aromatics in conversion reaction for treating catalytic diesel oil after hydrofining, wherein the purity of xylene products in conversion products reaches 96 percent, and C₉A and C₁₀The purity of A aromatic hydrocarbon is more than 98 percent, and the purity of light aromatic hydrocarbon products is close to that of aromatic hydrocarbon produced in the catalytic reforming process. However, after hydrofinishing, nitrogen-containing compounds in the catalytic diesel cannot be completely removed by the hydrofinishing reaction. Especially when the final boiling point of the catalytic diesel feedstock exceeds 360 c or even higher, the nitrogen content in the refined oil still exceeds 10ppm, which will adversely affect the light aromatics purity of the subsequent hydrocracking reaction.

At present, no ideal scheme is provided for further reducing the nitrogen content in the hydrofined catalytic diesel oil, so that the hydrocracking catalyst for producing aromatic hydrocarbon can exert the efficiency to the maximum extent, and the purity of the aromatic hydrocarbon product is improved.

Disclosure of Invention

Aiming at the problem that the purity of light aromatic hydrocarbon of heavy naphtha fraction is too low when the light aromatic hydrocarbon is taken as a target product in the prior art, the invention provides a hydrocracking method for producing high-quality light aromatic hydrocarbon from catalytic diesel. Has high aromatic hydrocarbon content in heavy naphtha, C₈、C₉And C₁₀The fraction directly meets the quality requirement of the aromatic hydrocarbon combination device for the raw materials.

The light aromatic hydrocarbon refers to aromatic hydrocarbon with the carbon number less than 10, and comprises C6 aromatic hydrocarbon, such as benzene; c7 aromatic hydrocarbons, such as toluene; c8 aromatic hydrocarbons, such as ethylbenzene, xylene; c9 aromatic hydrocarbons, such as methylethylbenzene, propylbenzene, trimethylbenzene; c10 aromatic hydrocarbons such as tetramethylbenzene, dimethylethylbenzene, diethylbenzene, etc.

One of the objects of the present invention is to provide a method for preparing light aromatic hydrocarbons.

The method for preparing the light aromatic hydrocarbon comprises the following steps:

1) contacting catalytic diesel with a hydrofining catalyst under a hydrogen condition to obtain a first material flow;

2) contacting a liquid phase material flow obtained after the impurities are separated from the first material flow with a denitrification catalyst under the condition of hydrogen to obtain a second material flow;

3) contacting the second stream with a hydrocracking catalyst under hydrogen conditions to obtain a third stream;

4) separating the third stream to obtain dry gas (hydrogen rich in methane and ethane), light hydrocarbon (stream rich in C3-C5 alkane), heavy naphtha rich in light aromatic hydrocarbon (stream rich in benzene-toluene, xylene, C₉Aromatic hydrocarbons and C₁₀Aromatic hydrocarbon stream) and heavy tail oil (containing C)₁₀The above heavy aromatics).

According to one aspect of the invention: step 1) of the method of the invention, contacting the catalytic diesel serving as raw oil with a hydrofining catalyst under a hydrogen condition to carry out hydrofining reaction: the catalytic diesel oil material flow and hydrogen gas are contacted with a hydrofining catalyst, most of sulfur and nitrogen impurities are removed (desulfurization and denitrification), and a selective saturation reaction of polycyclic aromatic hydrocarbon with one aromatic ring is kept. The hydrofinishing can be carried out in any manner and by any method conventionally known in the art, and is not particularly limited as long as the catalytic diesel fuel is subjected to desulfurization and denitrification, and the polycyclic aromatic hydrocarbons therein are subjected to hydrogenation saturation to retain one aromatic ring. The first material flow obtained by hydrofining the catalytic diesel mainly comprises refined catalytic diesel without most of sulfur and nitrogen impurities and a gas phase containing hydrogen sulfide and ammonia; the total retention of aromatics is greater than 90 wt%, preferably the total retention of aromatics is greater than 91%, and more preferably the total retention of aromatics is greater than 92%.

In the step 1) of the method, the hydrofining reaction is a catalytic diesel hydrofining technology known in the prior art. The hydrofining reaction condition can adopt the reaction condition of catalytic diesel hydrofining known in the prior art; the hydrofining catalyst can adopt any type of hydrofining catalyst existing in the prior art, as long as the aim of hydrofining the catalytic diesel oil in the step 1) can be fulfilled.

In the method of the present invention, the hydrofining reaction conditions of the hydrofining section in step 1) are preferably as follows:

the volume ratio of hydrogen to oil is 500-3000 Nm³/m³Preferably 800 to 2000Nm³/m³More preferably 1000 to 1500Nm³/m³；

The inlet temperature of the reactor is 280-420 ℃, preferably 300-410 ℃, and more preferably 310-390 ℃;

the hydrogen partial pressure is 5-10 MPa, preferably 5-8 MPa, and more preferably 6-7 MPa;

the airspeed is 0.5-2.0 hours^-1Preferably 0.6 to 1.5 hours^-1More preferably 0.8 to 1.2 hours^-1。

In the process of the present invention, the hydrofinishing catalyst of step 1) may preferably be the following:

comprises the following components in parts by weight: a1) 60-95 parts, preferably 65-90 parts, more preferably 70-90 parts of carrier; and b1) a group VIII-group VIB metal oxide, the weight portion of which is 5-40 portions, preferably 10-30 portions; the weight parts of the components are 100 parts based on the total weight parts of the carrier and the hydrogenation metal oxide.

The carrier comprises the following components in parts by weight: 60-98 parts of alumina; 0-40 parts of silicon oxide; based on the total weight of the alumina and the silicon oxide is 100 parts.

The metal oxide is preferably at least one selected from the group consisting of oxides of nickel, cobalt, molybdenum, tungsten, and iron. The hydrofinishing catalyst is preferably presulfided prior to reaction. The hydrogenation metal presulfiding adopts a catalyst presulfiding method which is common in the prior art.

The hydrofining catalyst of the invention is more excellent in nickel-molybdenum oxide/alumina bimetal and nickel-molybdenum-tungsten oxide/alumina trimetal type catalyst, and has better denitrification effect.

The hydrofining catalyst can be prepared by any method in the field, for example, the carrier can be prepared by the method of extruding, rolling ball or oil column forming in the field; the catalyst may be prepared by shaping the support and then impregnating the metal.

According to one aspect of the invention: in the step 2) of the method, impurity separation is carried out on the first material flow obtained after hydrofining, and after impurities such as hydrogen sulfide, ammonia and the like are separated, the liquid material flow is contacted with a denitrification catalyst for deep denitrification treatment.

The separation of impurities as described above preferably comprises steps of gas-liquid separation and stripping (e.g., hydrogen sulfide stripping) to obtain a liquid phase effluent from which impurities such as hydrogen sulfide and ammonia are separated, i.e., a first stream from which impurities are separated. The sulfur contained in the liquid phase effluent is all in the form of macromolecular thiophenic sulfur, wherein the sulfur content is less than 200ppm, preferably less than 100 ppm; its nitrogen content is less than 50ppm, preferably less than 30 ppm. More specifically, the separation techniques (including separation conditions, devices, etc.) common in the prior art, such as gas-liquid separation with gas-phase water-injection ammonia washing, liquid-phase stripping for hydrogen sulfide removal, etc., can be adopted.

And performing denitrification treatment on the liquid phase material flow after the impurities are separated. The denitrification treatment is deep denitrification, and high-boiling-point nitrogen-containing organic compounds in a liquid phase stream are removed. The method comprises the step of contacting the liquid phase material flow with a denitrification catalyst under the hydrogen condition to carry out catalytic denitrification reaction.

According to one aspect of the invention: the denitrification catalyst in the step 2) of the method comprises the following components in parts by weight: a) 1-30 parts of beta-nickel molybdate; b)0.5-10 parts of silicon dioxide; c) 60-98.5 parts of alumina, preferably 70-96 parts of alumina; the weight parts of the components are 100 parts based on the total weight parts of the nickel beta-molybdate, the silicon dioxide and the aluminum oxide.

The beta-nickel molybdate is an active component of the denitrification catalyst. The catalyst composition of the present invention comprises 1 to 30 parts, preferably 3 to 25 parts, specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30 parts by weight.

The silicon dioxide endows the denitrification catalyst with certain acidity, and improves the activity of the catalyst. The amount of the catalyst composition is 0.5 to 10 parts, preferably 1 to 8 parts, specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight.

The alumina is a binder of the denitrification catalyst of the invention, and is 60 to 98.5 parts, preferably 70 to 96 parts, by weight, of the catalyst composition of the invention, specifically 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 parts.

The denitrification catalyst of the invention can be prepared by any method in the field, for example, the denitrification catalyst is prepared by mixing the raw material components, forming by the method of kneading, extruding, rolling ball or oil column in the field, and then roasting. Specifically, the following method can be adopted:

fully mixing the components including beta-nickel molybdate (preferably in a powder form), amorphous silicon aluminum, sesbania powder and pseudo-boehmite, adding concentrated nitric acid and water, kneading, extruding and forming. Standing at room temperature, preferably drying for 5-30 hours at 60-120 ℃ for 10-24 hours; and then roasting the mixture to 530-560 ℃ in an air atmosphere and keeping the mixture for 2-6 hours to obtain the deep denitrification catalyst.

Alternatively, in the denitrification catalyst of the present invention, the β -nickel molybdate phase can also be generated in situ during the catalyst preparation process by introducing a metal salt precursor. The method specifically comprises the following steps: preparing nickel-molybdenum bimetallic aqueous solution from nickel nitrate hexahydrate and ammonium molybdate, wherein the molar ratio of nickel to molybdenum is 1; mixing amorphous silicon-aluminum, sesbania powder and pseudo-boehmite, adding the nickel-molybdenum bimetallic solution, concentrated nitric acid and water, kneading, extruding and molding. Standing at room temperature, preferably 8-30 hours, and drying at 80-120 ℃ for 10-24 hours; and then roasting the mixture to 530-560 ℃ in an air atmosphere and keeping the mixture for 2-6 hours to obtain the catalyst.

The (deep) denitrification catalyst of the present invention may preferably be subjected to a conventional activation treatment before the reaction. For example, the temperature is reduced to 400 to 500 ℃ in a hydrogen atmosphere and the temperature is maintained for 2 hours or more, preferably 2 to 24 hours.

The reaction conditions of the deep denitrification of the step 2) comprise:

the volume ratio of hydrogen to oil is 50-1000 Nm³/m³Preferably 100 to 800Nm³/m³More preferably 150 to 500Nm³/m³；

The inlet temperature of the reactor is 200-;

the hydrogen partial pressure is 0.5-10 MPa, preferably 1-8 MPa, and more preferably 3-6 MPa;

the airspeed is 0.2-4.0 hours^-1Preferably 0.5 to 3 hours^-1More preferably 0.6 to 2 hours^-1。

In the method of the present invention, the nitrogen content of the second stream obtained after the liquid phase stream is subjected to the above-mentioned deep denitrification treatment is less than 5ppm, preferably less than 2 ppm. The catalytic diesel oil is secondary processing oil, most of basic nitrogen contained in the primary raw material is removed in a hydrofining device through reaction, and some high-boiling nitrogen-containing organic compounds are remained. After the advanced denitrification treatment, only a trace amount of alkyl carbazole nitrogen-containing substances are left.

According to one aspect of the invention: step 3) of the method of the invention is to contact the second stream with a hydrocracking catalyst under hydrogen condition to carry out hydrocracking reaction. The hydrocracking reaction is to hydrocrack a second material flow obtained by separating impurities and deeply denitrifying after hydrofiningIs the third stream. The purpose of step 3) hydrocracking is to partially saturate C in the second stream₁₁ ⁺Carrying out ring opening and dealkylation on heavy aromatics to obtain a hydrocracking product; the hydrocracking product refers to aromatic hydrocarbon with carbon number less than 11, including C₆Aromatic hydrocarbons such as benzene; c₇Aromatic hydrocarbons such as toluene; c₈Aromatic hydrocarbons such as ethylbenzene, xylene; c₉Aromatic hydrocarbons such as methylethylbenzene, propylbenzene, trimethylbenzene; c₁₀Aromatic hydrocarbons, such as tetramethylbenzene, dimethylethylbenzene, diethylbenzene. Specifically, the hydrocracking reaction in the step is subjected to cracking reaction on the premise of reserving one aromatic ring of the polycyclic aromatic hydrocarbon in the first material flow heavy aromatic hydrocarbon, so that the saturation depth and the ring opening position are effectively controlled, and meanwhile, the isomerization and cracking of macromolecular non-aromatic hydrocarbon in the first material flow can be realized; maximizing the production of light aromatics at economic hydrogen consumption. The hydrocracking reaction of this step may be carried out in any manner and by any method of hydrocracking reactions conventionally known in the art, as long as the second stream can be hydrocracked into the third stream.

In the method of the present invention, the reaction conditions of the step 3) may adopt the reaction conditions of the hydrocracking reaction generally used in the prior art, and preferably include:

the volume ratio of hydrogen to oil is 800-5000 Nm³/m³Preferably 1000 to 4000Nm³/m³More preferably 1500 to 3000Nm³/m³；

The reactor inlet temperature is 280 ℃ to 450 ℃, preferably 300 ℃ to 430 ℃, more preferably 310 ℃ to 400 DEG C

The hydrogen partial pressure is 5-10 MPa, preferably 5-9 MPa, and more preferably 6-8 MPa;

the airspeed is 0.5-2.0 hours^-1Preferably 0.6 to 1.5 hours^-1More preferably 0.8 to 1.2 hours^-1。

In the method of the present invention, the hydrocracking catalyst of step 3) comprises the following components by weight: a) 5-80 parts of solid acid zeolite with a space index less than 18; b)0.05 to 8 parts of a group VIII metal; c) 3-25 parts of a group VIB metal oxide; d) 15-90 parts of a binder; the weight parts of the components are based on 100 parts of the total weight of the components.

The pore Space Index (SI) is an Index indicating the pore width of the zeolite. After a specific hydrogen type zeolite is loaded with 0.1-0.5 wt% of platinum or palladium noble metal, the hydrogen type zeolite is used for hydrocracking reaction of butylcyclohexane, and the molar ratio of isobutane to normal butane in a product is analyzed, namely the channel space index of the twelve-membered ring zeolite. The spaciousness of the pore channels of different zeolites can be characterized by the spatial index.

The solid acid zeolite having a space index of less than 18, preferably at least one of twelve membered ring zeolites having a space index of less than 18, and more preferably the solid acid zeolite having a space index of less than 18, as described in the hydrocracking catalyst of the present invention, includes at least one of beta zeolite, mordenite, ZSM-5, and the like.

The solid acid zeolite is present in the catalyst composition of the present invention in an amount of 5 to 80 parts, preferably 20 to 75 parts, more preferably 30 to 70 parts, specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 79, 80 parts by weight.

The silicon-aluminum molecular ratio of the solid acid zeolite is 20-200, such as 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 and 200. In a preferred range, the silicon to aluminum molecular ratio is between 40 and 160, e.g., 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160. In the hydrothermal synthesis method of the zeolite, the feeding silicon-aluminum ratio can be regulated and controlled by controlling the ratio of the silicon source to the aluminum source.

The group VIII metal in the hydrocracking catalyst of the present invention is preferably at least one selected from the group consisting of platinum, palladium, ruthenium, cobalt, nickel and iridium; more preferably at least one of platinum, palladium, cobalt and nickel. This component may be present in the final catalyst composition in any catalytically effective amount. The amount of the metal element is 0.05 to 8 parts, preferably 0.05 to 5 parts, more preferably 0.10 to 4 parts, specifically, for example, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.5, 4.6, 4.7, 4.5, 6, 7.6, 7.8, 3.9, 4.0, 4.2, 4.5, 6, 7.5, 6, 5, 6.6, 5, 6, 5, 6.6, 7, 6, 6.6, 5, 6, 5, 6, 7.6, 6, 5, 6.6, 6, 7.6, 6, 7.6, 7, 7.6, 6, 7, 7.0, 6.6.6, 6, 6.6, 6.

The group VIII metal component described above may be incorporated into the catalyst in any suitable manner, for example by co-precipitation with the catalyst support, co-gelling, ion exchange or impregnation, preferably impregnation with a water-soluble compound of the metal. Typical platinum group compounds which may be used are chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum dichloride, platinum tetrachloride hydrate, tetraamineplatinum chloride, tetraamineplatinum nitrate, platinum dichlorocarbonyldichloride, dinitrodiaminoplatinum, platinum chloride dihydrate, platinum nitrate, with tetraamineplatinum chloride being preferred as a source of the particularly preferred platinum component. Typical palladium group compounds which may be used are palladium chloride, palladium chloride dihydrate, palladium nitrate dihydrate, tetraamminepalladium chloride, preferably tetraamminepalladium chloride as a source of the particularly preferred palladium component. Typical cobalt family compounds that may be used are cobalt nitrate, cobalt chloride, cobalt oxalate, with cobalt nitrate being preferred as the source of the particularly preferred cobalt component. Typical nickel group compounds that may be used are nickel nitrate, nickel sulphate, nickel halides, nickel oxalate, nickel acetate, with nickel nitrate being preferred as a source of the particularly preferred nickel component. Typical iridium compounds which may be used are chloroiridate, iridium trichloride, preferably chloroiridate as a source of the particularly preferred iridium component. Typical ruthenium family compounds that can be used are ruthenium nitrate, ruthenium trichloride, preferably ruthenium trichloride as the source of the preferred ruthenium component.

The group VIB metal oxides in the hydrocracking catalyst of the present invention preferably comprise at least one of molybdenum oxides and tungsten oxides; wherein the oxide of molybdenum includes molybdenum dioxide, molybdenum trioxide, etc., and the oxide of tungsten includes tungsten dioxide, tungsten trioxide, etc.

The group VIB metal oxide described above may be present in the final catalyst composition in any catalytically effective amount, in parts by weight, from 3 to 25 parts, preferably from 3 to 20 parts, more preferably from 4 to 15 parts, specifically for example 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 parts, in the catalyst composition.

The group VIB metal oxides described above may be incorporated into the catalyst in any suitable manner, for example by co-precipitation with the catalyst support, co-gelling, kneading, ion exchange or impregnation, preferably using water-soluble impregnation of the metal compounds. Typical molybdenum family compounds that can be used are ammonium molybdate, molybdenum trioxide. Ammonium molybdate is preferred as a particularly preferred source of molybdenum oxide. Typical tungsten group compounds that may be used are ammonium tungstate, sodium tungstate, with ammonium tungstate being preferred as a particularly preferred source of tungsten oxide.

The binder in the hydrocracking catalyst of the present invention may be selected from catalyst binders commonly used in the art. The binder of the present invention preferably comprises at least one of alumina, silica, a silica-alumina composite, and amorphous silica-alumina.

In the catalyst composition of the present invention, the binder is 15 to 90 parts by weight, preferably 25 to 70 parts by weight, more preferably 30 to 60 parts by weight, specifically, for example, 15, 16, 17, 18, 20, 30, 40, 50, 60, 70, 80, and 90 parts by weight.

The binder of the present invention may be incorporated into the catalyst in any suitable manner, for example by kneading with zeolite, extruding, curing, drying and calcining to obtain the catalyst support.

According to the catalyst system of the present invention, conventional components of catalysts in the art, such as diatomaceous earth, activated clay, and the like, may also be included in the catalyst of the present invention. The amount may be a usual amount.

The hydrocracking catalyst of the present invention may be prepared by any method known in the art, and for example, the preparation of the catalyst of the present invention may include a step of forming a catalyst support containing the solid acid zeolite, supporting the metal, calcining and activating the formed catalyst support to obtain a catalyst precursor, and reducing the catalyst precursor. Wherein the carrier molding can be carried out by molding the solid acid zeolite together with the binder or the like by a method such as extrusion, rolling ball or oil column molding which is usual in the art; the supported metal may be prepared by coprecipitation, cogelling, kneading, ion exchange or impregnation of the metal with the catalyst support as is conventional in the art. Specifically, the following method can be adopted:

and mixing the solid acid zeolite with an adhesive, kneading, extruding, drying at 60-150 ℃, and roasting in an air atmosphere at 500-600 ℃ for 3-6 hours to obtain the required catalyst carrier. Preparing a bimetallic aqueous solution from a VIII group metal compound and a VIB group metal compound, impregnating a catalyst carrier by an isovolumetric impregnation method, drying at 60-150 ℃, and roasting at 450-520 ℃ for 1-4 hours in an air atmosphere to obtain a catalyst precursor. And reducing the catalyst precursor to 400-500 ℃ under the hydrogen condition and keeping for 2-24 hours (pre-reduction), thus obtaining the required hydrocracking catalyst.

In the preferred scheme of the invention, the VIII group metal and VIB group metal oxides on the hydrocracking catalyst have a special combination mode, provide a hydrogenation center with medium strength, effectively inhibit the occurrence of excessive hydrogenation side reaction in the hydrocracking reaction, and greatly improve the purity of aromatic hydrocarbon products in naphtha obtained by hydrocracking. In addition, in the method, the hydrofined product is subjected to impurity separation and then subjected to deep denitrification treatment, and then subjected to hydrocracking reaction, the processes of impurity separation and deep denitrification effectively remove ammonia and nitrogen-containing compounds generated by hydrofining, and the nitrogen content in the material flow is reduced to a very small amount, so that the inhibition effect of nitrogen in the material flow on zeolite acid centers is further eliminated, the cracking reaction of non-aromatic hydrocarbons in the obtained naphtha fraction is enhanced, and the purity of the aromatic hydrocarbons is further improved. Based on the method, a better technical effect is achieved in the direction of producing high-quality light aromatic hydrocarbon from catalytic diesel oil.

According to one aspect of the invention: in the method of the present invention, the step 4) of separating the third stream preferably includes subjecting the third stream to a separation process including a gas-liquid separation step and a fractionation step.

Specifically, the third material flow is subjected to gas-liquid separation, dry gas is separated out and discharged, liquid phase is fractionated, and fractions including the light hydrocarbon, heavy naphtha rich in light aromatic hydrocarbon and heavy tail oil are fractionated according to different temperature ranges. The heavy naphtha rich in light aromatics can be sent to an aromatics complex (PX unit) for aromatics product production. The gas-liquid separation and fractionation described above can be carried out by the techniques (including the separation conditions and apparatus) for gas-liquid separation and fractionation which are generally used in the art.

The method of the invention, wherein the third material flow is separated in the step 4) to obtain material flows including dry gas, light hydrocarbon, heavy naphtha (65-210 ℃ fraction) rich in light aromatic hydrocarbon, heavy tail oil (more than 210 ℃ fraction) and the like.

The method of the invention, wherein the heavy naphtha fraction obtained after the third stream is separated in step 4), the aromatic content in the heavy naphtha (65-210 ℃ fraction) is more than 80 wt%; wherein the aromatic content of the 136-144 ℃ cut fraction is more than 98 wt%, preferably more than 98.5 wt%, and the balance is non-aromatic; the aromatic content of the 145-170 ℃ cut fraction is more than 98wt percent, and the rest is non-aromatic hydrocarbon; the aromatic content of the 171- ­ 210 ℃ cut fraction was greater than 99 wt%, with the remainder being non-aromatic.

The boiling point of ethylbenzene is 136 ℃, the boiling point of p-xylene is 138 ℃, the boiling point of m-xylene is 139 ℃ and the boiling point of o-xylene is 144 ℃, so that the 136-144 ℃ fraction of the heavy naphtha obtained by the method can enrich the carbon and the octaarene to the maximum extent, and can be used as a raw material to be sent to an adsorption separation or crystallization separation device to produce the p-xylene. The fraction at 145-170 ℃ and the fraction at 171-210 ℃ are respectively rich in C9A and C10A, and are sent to an aromatic hydrocarbon combination unit to be used as raw materials of a toluene disproportionation unit. The lower fraction of the heavy naphtha at 65-135 ℃ obtained by the invention is sent to a solvent extraction unit of an aromatic hydrocarbon combination unit to separate out pure benzene and toluene, and the toluene can be converted into dimethylbenzene through disproportionation and transalkylation reactions.

The hydrocracking method for producing light aromatics, which is disclosed by the invention, has the advantages that the total aromatic content of the catalytic diesel serving as the raw oil is more than 70 wt%, the initial distillation point is more than or equal to 160 ℃, the final distillation point is less than or equal to 380 ℃, the sulfur content is between 200-15000wt ppm, and the nitrogen content is between 100-1500wt ppm. More preferably, the catalytically cracked diesel feedstock has a total aromatics content of greater than 80%, wherein bicyclic aromatics comprise 70 wt% and monocyclic and tricyclic aromatics comprise about 15 wt% each. The bicyclic aromatic hydrocarbon mainly comprises naphthalene series, indene series, acenaphthene and other bicyclic aromatic hydrocarbons, and the tricyclic aromatic hydrocarbon comprises anthracene, phenanthrene and the like.

The composition of the catalytic diesel oil is not particularly limited, and the catalytic diesel oil can be derived from crude oil of different producing areas, and the composition is different. By way of example, however, the catalytic diesel fuel contains predominantly alkanes, cycloalkanes, alkenes, sulfur-containing hydrocarbons, nitrogen-containing hydrocarbons, C₁₁ ⁺Alkylbenzene and polycyclic aromatic hydrocarbon, etc. Wherein, C₁₁ ⁺The content range of the alkylbenzene is 10-40 wt%, the content range of the polycyclic aromatic hydrocarbon is 15-50 wt%, the content range of the sulfur is 200-15000wt ppm, the content range of the nitrogen is 100-1500wt ppm, and the others are high-boiling-point alkane, cyclane and olefin.

It is another object of the present invention to provide such a system for producing high quality light aromatics.

The system of the invention comprises:

a first device; configured to receive the catalytic diesel and to emit the first stream;

a second device; configured to receive said first stream separated from impurities in a liquid phase stream and to discharge said second stream;

a third device; configured to receive the second stream and to discharge the third stream;

a first separation zone; configured to receive the third stream; discharging fractions including the dry gas, light hydrocarbons, heavy naphtha rich in light aromatics, and heavy tail oil.

In the system, the reactor in the first device is a fixed bed reaction system, and a hydrofining catalyst is filled in the reactor; a recycle hydrogen system is preferably provided.

In the system, the reactor in the third device is a fixed bed reaction system and is filled with a hydrocracking catalyst; a recycle hydrogen system is preferably provided.

In the system, the second device is a catalytic denitrification device, and the reactor is a fixed bed reaction system filled with the denitrification catalyst.

According to the system, the first separation zone comprises a gas-liquid separator and a fractionation system which are sequentially connected, and fractions including the dry gas, the light hydrocarbon, the heavy naphtha rich in light aromatics and the heavy tail oil are sequentially obtained through separation.

Further preferably, the third stream is passed through a gas-liquid separator to separate dry gas and liquid phase streams, and the liquid phase stream is fractionated by a fractionation system (e.g., a fractionator) to separate fractions including the light hydrocarbons, heavy naphtha rich in light aromatics, and heavy tail oil at different temperature ranges. The heavy naphtha rich in light aromatics can be sent to an aromatics complex (PX unit) for aromatics product production. The gas-liquid separation device and the fractionation device can adopt the gas-liquid separation device and the fractionation system which are commonly used in the prior art, such as a gas-liquid separator, a fractionation tower and the like.

In the system, a second separation area is arranged between the first device and the second device; the second separation zone is configured to receive the first stream and discharge a stream comprising a gas phase, a hydrogen sulfide and ammonia stream, and a liquid phase stream after separation of impurities. The separation device of the second separation zone can adopt a separation device which is common in the prior art, such as a gas-liquid separator (with gas phase water injection for ammonia washing), a stripping device (such as a stripping tower of a liquid phase stripping hydrogen sulfide removal device) and the like.

In the method, the catalytic diesel oil is subjected to hydrofining, the total retention rate of aromatic hydrocarbon is more than 90 wt%, and the nitrogen content of a liquid phase material flow after impurities are separated is less than 50 ppm. After further advanced denitrification treatment, the nitrogen content is reduced to less than 5ppm, preferably less than 2ppm, and the retention of aromatic hydrocarbon in the process is kept at a high level. The hydrocracking catalyst is a typical metal/zeolite solid acid dual-function catalyst on zeolite solid acidThe strong acid center of (2) is an active center of a ring-opening reaction of the tetralin-series and indene-series aromatic hydrocarbons and is also an active center of a non-aromatic hydrocarbon cracking reaction. Through the deep denitrification process, on the premise of ensuring the retention rate of aromatic hydrocarbon, the nitrogen content of the raw material is greatly reduced, the zeolite strong acid center fully plays a catalytic role in the hydrocracking reaction process, the non-aromatic hydrocarbon cracking reaction is further deepened, high-quality light aromatic hydrocarbon is directly produced from the catalytic cracking light diesel oil, and a higher technical effect is achieved. The catalytic diesel oil material flow is subjected to hydrofining, deep denitrification and hydrocracking in sequence, and C₁₁ ⁺Conversion per pass of aromatics (C)₁₀The conversion rate per pass of the above hydrocarbons into carbon ten and below monocyclic aromatics) is more than 75 wt%, the aromatic content of the 136-144 ℃ cut fraction is more than 98 wt%, and the aromatic content of the 145-170 ℃ cut fraction is more than 98 wt%; the aromatic hydrocarbon content of the cut fraction at the temperature of 171 ℃ and 210 ℃ is more than 99 weight percent, and the aromatic hydrocarbon composition can provide a high-quality aromatic hydrocarbon raw material for an aromatic hydrocarbon combination device.

Drawings

FIG. 1 is a schematic diagram of a hydrocracking process for producing high quality light aromatics according to the present invention. The drawings are intended to illustrate the invention and not to limit it.

1 is catalytic diesel raw oil, 2 is a hydrofining reactor, 3 is a hydrofining product (a first material flow), 4 is a second separation area comprising a gas-liquid separation system and a hydrogen sulfide stripping tower, 5 is a liquid material flow after separating impurities such as hydrogen sulfide, ammonia and the like; 7 is a denitrification device, 8 is a denitrification product (second stream), 9 is a hydrocracking (hydrocracking) reactor, 10 is a hydrocracking reaction product (third stream), 11 is a first separation zone, 12 is a light hydrocarbon product comprising LPG (liquefied petroleum gas), 13 is heavy naphtha rich in light aromatics, and 14 is discharged heavy tail oil.

Fig. 1 is a schematic process flow diagram of a hydrocracking process for producing high-quality light aromatics from catalytic diesel fuel according to the present invention, in which many conventional devices such as pumps, compressors, heat exchangers, extraction devices, pipelines, etc. are omitted, but such devices are well known to those skilled in the art. As shown in fig. 1, the flow of the method of the present invention is described in detail as follows:

the catalytic diesel oil 1 as raw oil enters a hydrofining reactor 2 filled with hydrofining catalyst together with hydrogen to obtain hydrofined catalytic diesel oil containing impurities such as hydrogen sulfide and ammonia, namely a hydrofined product 3 (first material flow); the first material flow passes through a gas-liquid separation system of the second separation area 4 and a hydrogen sulfide stripping tower to separate impurities such as hydrogen sulfide, ammonia and the like obtained by denitrification and desulfurization in the hydrofining process, and then a liquid phase material flow 6 after the impurities are separated is obtained. The material flow enters a denitrification device 7 for deep denitrification, and the obtained denitrification product, namely a second material flow 8 and hydrogen enter a hydrocracking reactor 9 filled with a hydrocracking catalyst for hydrocracking reaction. Hydrocracking reaction products (third material flow) 10 which are rich in light hydrocarbon and light aromatic hydrocarbon and obtained after hydrocracking reaction enter a first separation zone 11, and dry gas, light hydrocarbon 12 containing LPG, heavy naphtha 13 rich in light aromatic hydrocarbon and discharged heavy tail oil 14 are obtained through separation.

Specifically, the first separation zone 11 comprises a gas-liquid separator and a fractionation column (not shown in detail in the drawings) coupled in series.

Detailed Description

While the present invention will be described in detail and with reference to the specific embodiments thereof, it should be understood that the following detailed description is only for illustrative purposes and is not intended to limit the scope of the present invention, as those skilled in the art will appreciate numerous insubstantial modifications and variations therefrom.

All publications, patent applications, patents, and other references mentioned in this specification are herein incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, including definitions, will control.

When the specification concludes with claims with the heading "known to those skilled in the art", "prior art", or the like, to derive materials, substances, methods, procedures, devices, or components, etc., it is intended that the subject matter derived from the heading encompass those conventionally used in the art at the time of filing this application, but also include those that are not currently in use, but would become known in the art to be suitable for a similar purpose.

The endpoints of the ranges and any values disclosed in the present document are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein. In the following, various technical solutions can in principle be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

The following detailed description describes specific embodiments of the present invention, but the present invention is not limited to the specific details in the embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It is to be further understood that the various features described in the following detailed description may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention can be made, as long as the technical solution formed by the combination does not depart from the idea of the present invention, and the technical solution formed by the combination is part of the original disclosure of the present specification, and also falls into the protection scope of the present invention.

Where not explicitly indicated, reference to pressure within this specification is to gauge pressure.

The space velocity mentioned in this specification is, unless explicitly stated, the liquid hourly space velocity LHSV.

Unless otherwise expressly indicated, all percentages, parts, ratios, etc. mentioned in this specification are by weight unless otherwise not in accordance with the conventional knowledge of those skilled in the art.

The composition analysis of the catalyst involved in the present invention adopts the analysis method existing in the field. For example, the composition of the catalyst can be analyzed by ICP (inductively coupled plasma) and XRF (X-ray fluorescence) methods for the selective conversion catalyst. The composition ratio of the metal and its oxide is determined by XPS (X-ray photoelectron spectroscopy). The ICP test conditions were: the Varian 700-ES series XPS instrument. XRF test conditions were: rigaku ZSX 100e model XRF instrument. XPS test conditions: perkin Elmer PHI 5000C ESCA type X-ray photoelectron spectrometer with Mg K exciting light source, operation voltage l0kV, current 40mA, vacuum degree 4.0X 10^-8Pa。

In the invention, the hydrocarbon group composition of the raw material and the hydrofined product is analyzed by the full two-dimensional gas chromatography. The full two-dimensional chromatograph (GC × GC) consists of an Agilent7890A gas chromatograph from Agilent, usa equipped with a hydrogen Flame Ionization Detector (FID) and a snow science solid state thermal modulator (SSM). The chromatographic column 1 is an HP-PONA capillary column, and adopts a temperature program of heating up to 50 ℃ for 2min, then heating up to 275 ℃ at a speed of 1.5 ℃/min, and maintaining the constant temperature for 2 min. The chromatographic column 2 is a DB-17HT capillary column. With a modulation period of 10s, the control software is SSM _ viewer and the data processing software is FreeMat.

In the present invention, the hydrocracking product composition was determined by gas chromatography. The chromatography model is Agilent7890A, and is prepared by preparing FID detector and FFAP capillary chromatography column, separating, heating the chromatography column at 90 deg.C for 15min, heating to 220 deg.C at 15 deg.C/min, and maintaining for 45 min.

Calculation of the data of the main results of the examples and comparative examples:

1. the calculation formula of the total aromatic retention rate of the hydrofining reaction is as follows:

2、C₁₁ ⁺the conversion of aromatics is calculated by the formula:

wherein, for the two-stage two-agent process of the embodiment of the invention, the C is₁₁ ⁺The conversion of aromatics is based on C before and after the hydrocracking reactor₁₁ ⁺Calculating aromatic hydrocarbon; for the one-stage two-agent process of comparative example, C₁₁+ aromatics conversion based on C fed to the hydrofinishing reactor₁₁ ⁺Aromatics content and C11+ aromatics content exiting the hydrocracking reactor.

3. The calculation formula of the aromatic hydrocarbon content in the heavy naphtha is as follows:

4. the purity of the C-octa aromatic hydrocarbon in the heavy naphtha is calculated by the following formula:

5. the purity of carbon nonaaromatics in heavy naphtha is calculated by the following formula:

6. the purity of the decaaromatic hydrocarbons in the heavy naphtha is calculated by the following formula:

the catalyst starting materials for the inventive and comparative examples are commercially available.

Comparative example 1

The process flow comprises the following steps: the catalytic diesel raw material 1 is processed by adopting a traditional single-stage double-agent method, namely, the catalytic diesel serving as the raw material oil 1 is directly subjected to hydrocracking without separating impurities after being subjected to hydrofining; the catalysts are respectively a hydrofining catalyst and a hydrocracking catalyst, and are sequentially filled in two fixed bed reactors connected in series. The properties of the raw materials are shown in Table 1, and the aromatic hydrocarbon content of the catalytic diesel oil of the raw material oil 1 is 85.05 wt%.

Catalyst:

hydrorefining catalyst a 1: adding 2g of sesbania powder, 9ml of nitric acid and 60ml of water into 100g of pseudo-boehmite, kneading into a cluster, extruding into strips, curing at room temperature for 24h, drying at 100 ℃ for 12h, and roasting at 550 ℃ in air atmosphere for 3h to obtain the hydrofining catalyst carrier. 7.90g of nickel nitrate hexahydrate, 8.71g of ammonium molybdate, 9.18g of ammonium metatungstate and 10ml of ammonia were dissolved in water to give 50ml of a clear solution. Adding 50g of hydrofining catalyst carrier into 50ml of solution to soak for 3 hours in an isovolumetric soaking mode, drying for 12 hours at 110 ℃, and roasting for 4 hours at 500 ℃ in an air atmosphere to obtain a hydrofining catalyst A1: the composition is 3.0 wt% NiO-10.5 wt% MoO₃-12.7wt％WO₃/73.8wt％Al₂O₃It contains three metals of nickel, molybdenum and tungsten.

Hydrocracking catalyst B1: uniformly mixing 43g of USY molecular sieve (the silica-alumina ratio is 12, and the dry basis content is 90 wt%), 72.3g of pseudo-boehmite and 2g of sesbania powder, adding 12ml of nitric acid and 90ml of water, kneading into a cluster, extruding into strips, curing at room temperature for 24h, drying at 110 ℃ for 12h, and roasting at 550 ℃ in an air atmosphere for 3h to obtain the hydrocracking catalyst carrier. 4.34g of nickel nitrate, 5.75g of ammonium molybdate and 20ml of aqueous ammonia were dissolved in water to give a 50ml aqueous solution. Taking 50g of hydrocracking catalyst carrier, adding 50ml of solution to soak for 3 hours in an isovolumetric soaking mode, drying for 12 hours at 110 ℃, roasting for 4 hours at 500 ℃ in air atmosphere to obtain hydrocracking catalyst B1: the composition is 2.0 wt% NiO-8.4 wt% MoO₃/39.0wt％USY-50.6wt％Al₂O₃The catalyst contains two metals of nickel and molybdenum, and adopts a USY molecular sieve as a solid acid component.

Pre-sulfurizing a catalyst: injecting a cyclohexane solution containing 0.5 percent of carbon disulfide into a fixed bed reactor sequentially filled with a hydrofining catalyst and a hydrocracking catalyst, raising the temperature from room temperature to 360 ℃ of the vulcanization end point temperature according to a program of 10 ℃/h, and keeping the temperature for 12h to finish the pre-vulcanization of the hydrofining and hydrocracking catalyst.

The composition of the hydrofining catalyst A1' after vulcanization is 3.1 wt% NiS-10.2 wt% MoS₂-13.2wt％WS₂/73.5wt％Al₂O₃The group VIB and group VIII metals are present in the sulfided form. The composition of the hydrogenated cracking catalyst B1' after being vulcanized is 2.1 wt% NiS-8.5 wt% MoS₂/38.5wt％USY-50.9wt％Al₂O₃The group VIB and group VIII metals are present in the sulfided form.

The hydrorefining and hydrocracking reaction conditions and corresponding catalysts are shown in table 2.

TABLE 1

	Raw oil 1
		Density (4 ℃ C.)	0.948
Sulfur (wtppm)	1050
		Nitrogen (wtppm)	518
Non-aromatic hydrocarbons (wt)	14.95
		Monocyclic aromatic hydrocarbon (wt%)	36.24
Polycyclic aromatic hydrocarbons (wt%)	48.81
		Distillation test (D-86)	℃
Initial boiling point	185
		5％	197
10％	210.5
		30％	253
50％	269
		70％	284
90％	317
		End point of distillation	351

TABLE 2

The pressure of the hydrocracking section is the same as that of the hydrofining section.

After the catalytic diesel raw oil 1 is mixed with hydrogen, the mixture sequentially passes through a hydrofining section and a hydrocracking section of a fixed bed reactor, and heavy naphtha fraction at 65-210 ℃ and heavy fraction above 210 ℃ are separated in a fractionation system.

Can be calculated, C₁₀The per pass conversion of the above hydrocarbons was 57.24 wt%. The composition of the heavy naphtha fraction at 65-210 ℃ is shown in Table 3: wherein, the total content of the aromatic hydrocarbon is 60.01 wt%, the purity of the 136-144 ℃ C. octa-aromatic hydrocarbon is 59.49 wt%, the purity of the 145-170 ℃ C. nona-aromatic hydrocarbon is 77.99 wt%, and the purity of the 171-210 ℃ C. deca-aromatic hydrocarbon is 80.03 wt%.

TABLE 3

[ example 1 ]

The process flow comprises the following steps: the hydrocracking process flow for producing high-quality light aromatics by catalyzing diesel oil in the embodiment is shown as a figure 1. The method comprises the steps of separating fractions including dry gas, light hydrocarbon, heavy naphtha fraction and heavy tail oil after the catalytic diesel oil is subjected to hydrofining, impurity separation, deep denitrification and hydrocracking reaction. The advanced denitrification treatment of the embodiment adopts a catalytic denitrification method, and the denitrification device is a fixed bed reaction system filled with a denitrification catalyst. Feed oil was the same as feed oil 1 of comparative example 1 (catalytic diesel 1).

Catalyst:

the hydrofining catalyst is the hydrofining catalyst A1 of the comparative example 1, and the hydrofining catalyst A1' is presulfided under the same conditions. The hydrofinishing catalyst and reaction conditions were the same as in comparative example 1 (see table 2).

Hydrocracking catalyst B2: 70 wt% of beta zeolite with a space index of 14.8 (the SAR is 25) and 30 wt% of alumina are kneaded, extruded and formed to obtain the catalyst carrier. And preparing a proper amount of nickel nitrate and ammonium tungstate into a clear solution, soaking in the same volume, drying at 100 ℃, and roasting in air at 500 ℃ for 2 hours to obtain the catalyst precursor. The catalyst precursor is reduced to 450 ℃ for 4 hours under the hydrogen condition, and the required hydrocracking (hydrocracking) catalyst can be obtained. Based on the total weight of the catalyst of 100 parts by weight, the catalyst comprises3.5 parts of Ni-3.2 parts of WO₂2.07 parts of WO₃50 parts of beta zeolite-41.23 parts of Al₂O₃。

Deep denitrification catalyst C1: after 15g of beta-nickel molybdate (powder), 35g of amorphous silicon aluminum (silica content 20 wt%, product of Sasol corporation), 2g of sesbania powder and 50g of pseudo-boehmite were sufficiently mixed, 8ml of concentrated nitric acid and 90ml of water were added, and kneading, strip extrusion and molding were carried out. Standing at room temperature for 24 hours, drying at 100 ℃ for 12 hours, roasting at 550 ℃ in an air atmosphere, and keeping for 4 hours to obtain the deep denitrification catalyst C1. The C1 catalyst composition was 19.23 parts of beta-nickel molybdate/7.18 parts of SiO₂-73.59 parts of Al₂O₃。

The catalyst C1 was loaded into a fixed bed reactor and reduced to 450 ℃ in a hydrogen atmosphere and held for 4h to complete the catalyst activation.

The specific process flow and the product are as follows:

the catalytic diesel raw oil 1 (same as the catalytic diesel raw material of comparative example 1) is first hydrofined, and the reaction conditions and hydrofining catalyst of hydrofining are the same as those of comparative example 1. The catalytic diesel oil and hydrogen are mixed and then enter a hydrofining reactor to remove most of sulfur and nitrogen impurities in the catalytic diesel oil, and the polycyclic aromatic hydrocarbon is saturated into hydrocarbon containing only one aromatic ring. Table 4 lists the sulfur and nitrogen content, density, aromatic hydrocarbon content, and distillate distribution of the liquid phase stream after separation of impurities from the hydrofinished product. The sulfur content and the nitrogen content of the liquid phase material flow of the hydrofined product after impurity separation are 87ppm and 8.6ppm respectively. The total aromatics retention of the hydrofinishing process (first stream) was 91.17 wt%, calculated from the aromatics composition data.

TABLE 4

	Hydrorefining the product fractionLiquid phase stream after impurity separation
		Density (4 ℃ C.)	0.927
Sulfur (wtppm)	87
		Nitrogen (wtppm)	8.6
Non-aromatic hydrocarbons (wt%)	22.46
		Monocyclic aromatic hydrocarbon (wt%)	58.95
Polycyclic aromatic hydrocarbons (wt%)	18.59
		Distillation test (D-86)	℃
Initial boiling point	185
		5％	197
10％	210.5
		30％	253
50％	269
		70％	284
90％	317
		End point of distillation	351

The first material flow of the catalytic diesel oil after hydrofining is subjected to impurity separation: the method comprises the steps of carrying out gas-liquid separation on the first material flow, carrying out nitrogen stripping for 3 hours under normal pressure, and fully removing hydrogen sulfide dissolved in the first material flow.

And after impurities are separated from the first material flow, the first material flow enters the fixed bed device filled with the denitrification catalyst for deep denitrification treatment. The catalytic denitrification conditions are as follows: the inlet temperature is 330 ℃, and the space velocity is 1.0h^-1The pressure is 3.0MPa, and the hydrogen-oil ratio is 400 (v/v). After denitrification, the change of the sulfur and nitrogen content of the material flow is shown in Table 5, the nitrogen content is greatly reduced to 1.5ppm, the total sulfur content is also reduced to 27ppm, and the group composition is not obviously changed.

TABLE 5

And the second stream after the deep denitrification treatment enters a hydrocracking reactor for hydrocracking reaction to obtain a third stream which is a hydrocracking product. The reaction conditions and hydrocracking catalysts are shown in Table 6.

TABLE 6

Hydrocracking catalyst B2	3.5 parts of Ni-3.2 parts of WO22.07 parts of WO350 parts of beta zeolite-41.23 parts of Al2O3
		Operating pressure (Hydrogen partial pressure)	6.5Mpa
Reaction temperature	380 ℃ at the inlet
		Airspeed	1.0h-1
Hydrogen to oil ratio	2000(v/v)

Said third stream is separated in a fractionation system in a first separation zone into a heavy naphtha fraction at 65-210 ℃ and a heavy fraction at > 210 ℃.

The calculation can obtain: c₁₁ ⁺The conversion per pass of aromatics was 93.56 wt%. The composition of the heavy naphtha fraction at 65-210 ℃ is shown in Table 7: wherein, the total content of aromatic hydrocarbon is 91.63 wt%; the purity of the 136-144 ℃ C hydrocarbon octaarene is 98.90 wt%; 145-170 ℃ carbon nonaarene purity 98.97 wt%; the purity of the carbon deca-aromatic hydrocarbon at 171 ℃ and 210 ℃ is 99.61 wt%.

TABLE 7

[ example 2 ]

The process flow comprises the following steps: the hydrocracking process flow for producing high-quality light aromatics by catalyzing diesel oil in the embodiment is shown as a figure 1. The method comprises the steps of separating fractions including dry gas, light hydrocarbon, heavy naphtha fraction and heavy tail oil after the catalytic diesel oil is subjected to hydrofining, impurity separation, deep denitrification and hydrocracking reaction. The advanced denitrification treatment of the embodiment adopts a catalytic denitrification method, and the denitrification device is a fixed bed device filled with denitrification catalyst.

The properties of the feedstock are shown in Table 11, and the aromatic content of the catalyzed diesel of feedstock 2 is 79.50 wt%.

Catalyst:

hydrorefining catalyst a 2: adding 2g of sesbania powder, 9ml of nitric acid and 60ml of water into 100g of pseudo-boehmite, kneading into a cluster, extruding into strips, curing at room temperature for 24h, drying at 100 ℃ for 12h, and roasting at 550 ℃ in air atmosphere for 3h to obtain the hydrofining catalyst carrier. 10.32g of nickel nitrate hexahydrate, 20.96g of ammonium molybdate and 10ml of ammonia were dissolved in water to give 50ml of a clear solution. Adding 50g of hydrofining catalyst carrier into 50ml of solution to soak for 3 hours in an isovolumetric soaking mode, drying for 12 hours at 110 ℃, and roasting for 4 hours at 500 ℃ in an air atmosphere to obtain a hydrofining catalyst A2: 3.8 wt% NiO-24.5 wt% MoO₃/71.7wt％Al₂O₃And contains bimetal components of nickel and molybdenum.

Pre-vulcanizing: and (3) injecting a cyclohexane solution containing 0.5% of carbon disulfide into a fixed bed reactor filled with the hydrofining catalyst, raising the temperature from room temperature to 360 ℃ of the vulcanization end point according to a program of 10 ℃/h, and keeping the temperature for 12h to finish the pre-vulcanization of the hydrofining catalyst A2. The composition of the hydrofining catalyst A2' after being vulcanized is 4.0 wt% NiS-25.9 wt% MoS₂/70.1wt％Al₂O₃The group VIB and group VIII metals are present in the sulfided form.

The hydrofinishing reaction conditions and corresponding catalysts are shown in table 9.

TABLE 9

The deep denitrification catalyst C2 is prepared by dissolving 12.8g of nickel nitrate hexahydrate, 7.8g of ammonium molybdate and 6g of citric acid in water to obtain 50ml of nickel-molybdenum bimetallic solution. 65g of amorphous silicon-aluminum (silica content 9 wt.%)Sasol company products), 2g of sesbania powder and 30g of pseudo-boehmite are fully mixed, 50ml of nickel-molybdenum bimetallic solution, 8ml of concentrated nitric acid and 30ml of water are added, and the mixture is kneaded and extruded to form strips. Standing at room temperature for 20 hours, drying at 110 ℃ for 12 hours, and roasting in an air atmosphere to 560 ℃ and keeping for 4 hours to obtain the deep denitrification catalyst C2. The composition of the C2 catalyst was 11.95 parts of beta-nickel molybdate/5.67 SiO₂82.38 parts of Al₂O₃。

The catalyst C2 was loaded into a fixed bed reactor and reduced to 450 ℃ in a hydrogen atmosphere and held for 4h to complete the catalyst activation.

Hydrocracking catalyst B3: fully mixing hydrogen mordenite (SAR ═ 45) with a pore space index of 7.1, hydrogen beta zeolite (SAR ═ 25) with a pore space index of 14.8, hydrogen ZSM-5(SAR ═ 27) with a pore space index of 0.7 and pseudo-boehmite, kneading, extruding, drying at 120 ℃, and roasting at 550 ℃ for 4 hours to obtain the required catalyst carrier. Preparing a trimetal solution by using palladium chloride, nickel nitrate and ammonium molybdate, impregnating a catalyst carrier by using an isometric impregnation method, drying at 120 ℃, and roasting for 2 hours at 500 ℃ in an air atmosphere to obtain a catalyst precursor. The catalyst precursor was reduced to 450 ℃ under hydrogen and held for 8 hours to complete the catalyst activation. The catalyst comprises the following components in parts by weight, based on 100 parts by weight of the total weight of the catalyst: 0.2 part of Pd-6.5 parts of Ni-4.2 parts of MoO₂-9 parts MoO₃35 parts of mordenite-10 parts of beta zeolite-11 parts of ZSM-5-24.1 parts of Al₂O₃。

The hydrocracking reaction conditions and corresponding catalysts are shown in table 10.

Watch 10

The specific process flow and the product are as follows:

the first hydrofining of the catalytic diesel feed oil 2 was carried out, and the reaction conditions and hydrofining catalysts for the hydrofining are shown in Table 9. The catalytic diesel oil and hydrogen are mixed and then enter a hydrofining reactor to remove most of sulfur and nitrogen impurities in the catalytic diesel oil, and the polycyclic aromatic hydrocarbon is saturated into hydrocarbon containing only one aromatic ring. Table 11 lists the sulfur nitrogen content, density, aromatic hydrocarbon content, and fraction distribution in the liquid phase stream after separation of impurities from feed oil 2 and the hydrofinished product (first stream). It can be seen that the sulfur content and the nitrogen content of the liquid phase stream after separation of impurities from the hydrorefined product were 109ppm and 24ppm, respectively. The total aromatics retention of the hydrofinishing process (first stream) was 92.68 wt%, calculated from the aromatics composition data.

TABLE 11

The first material flow of the catalytic diesel oil after hydrofining is subjected to impurity separation: the method comprises the steps of carrying out gas-liquid separation on the first material flow, carrying out nitrogen stripping for 3 hours under normal pressure, and fully removing hydrogen sulfide dissolved in the first material flow.

And the first material flow is subjected to impurity separation and then enters the fixed bed device filled with the denitrification catalyst to perform catalytic denitrification reaction. At 350 ℃, 2.0MPa, 300 hydrogen-oil ratio and 1.5h airspeed^-1And (3) reacting under the condition. The change of the sulfur and nitrogen contents of the material flows before and after hydrodenitrogenation is shown in a table 12, the nitrogen content is greatly reduced to 3.7ppm, the total sulfur content is also reduced to 32ppm, and the group composition is not obviously changed.

TABLE 12

	Liquid phase material flow after impurity separation of hydrofining product	Denitrified second stream
			Sulfur (wtppm)	109	32
Nitrogen (wtppm)	24	3.7
			Non-aromatic hydrocarbons (wt)	26.32	26.75
Monocyclic aromatic hydrocarbon (wt%)	43.91	42.19
			Polycyclic aromatic hydrocarbons (wt%)	29.77	31.06

And the second stream after the deep denitrification treatment enters a hydrocracking reactor for hydrocracking reaction to obtain a third stream which is a hydrocracking product.

Said third stream is separated in a fractionation system in a first separation zone into a heavy naphtha fraction at 65-210 ℃ and a heavy fraction at > 210 ℃.

The calculation can obtain: c₁₁ ⁺The conversion per pass of aromatics was 82.54 wt%. In the fractionating system, a heavy naphtha fraction at 65-210 ℃ and a heavy fraction at > 210 ℃ are separated. The results of the compositional analysis of the 65-210 ℃ heavy naphtha fraction are shown in Table 13: wherein, the total content of aromatic hydrocarbon is 91.87 wt%; the purity of the 136-144 ℃ C hydrocarbon octaarene is 99.17 wt%; 145-170 ℃ purity of the nonaromatic hydrocarbon 99.07 wt%; the purity of the carbon deca-aromatic hydrocarbon at the temperature of 171 ℃ and 210 ℃ is 99.38 wt%.

Watch 13