CN117736763A - A method to achieve fine separation of aromatic hydrocarbons in oil based on combined simulated moving bed technology - Google Patents

Abstract

The invention relates to a method for realizing fine separation of aromatic hydrocarbon in oil products based on a combined simulated moving bed process. The method adopts porous carbon material, molecular sieve and metal modified material thereof as adsorbent, and aromatic hydrocarbon-containing oil products firstly pass through a primary simulated moving bed to adsorb and separate aromatic hydrocarbon components in diesel oil, thus obtaining two major categories of high-purity mixed aromatic hydrocarbon and non-aromatic hydrocarbon. And then sequentially passing the high-purity mixed aromatic hydrocarbon component through two stages of simulated moving beds containing the high-selectivity adsorption material to sequentially obtain monocyclic, bicyclic and tricyclic aromatic hydrocarbon components. Through the combination of the three simulated moving bed devices, the fine separation of multi-component aromatic hydrocarbon in the diesel oil is efficiently realized, and finally, the high-purity aromatic hydrocarbon component and the low-aromatic hydrocarbon high-quality gasoline and diesel oil are obtained. The process for separating the multi-component aromatic hydrocarbon in the oil product by the combined simulated moving bed adsorption has the characteristics of low energy consumption, low adsorption-regeneration temperature, good operation continuity and strong regulating capability, can obtain a plurality of aromatic hydrocarbon products in one step, and has wide application prospect.

Description

A method to realize fine separation of aromatics in oil based on combined simulated moving bed process method

Technical field

The invention belongs to the technical field of separation and purification of mixed aromatic hydrocarbons in oil products, and specifically relates to a method and technology for achieving fine separation of aromatic hydrocarbons in oil products based on a combined simulated moving bed process.

Background technique

For my country's refining industry, the quality of crude oil is poor, mainly heavy oil and low-quality oil. The secondary processing is mainly catalytic cracking and coking. The aromatic content in catalytic cracking diesel and coking diesel is high, resulting in ten-year-old diesel. It has a low hexane number and poor combustion performance, and the demand for diesel downstream derivatives (aromatics, olefins, etc.) is growing much faster than that of refined oil. If the various components in diesel can be separated to obtain high-purity paraffins, cycloalkanes, monocyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons, the high-purity aromatic hydrocarbons can be used as high-quality aromatic hydrocarbon solvents or high-quality BTX (benzene, toluene, xylene ) to increase the production of raw materials, which not only realizes the classified management of diesel components and provides raw materials for efficient conversion and accurate processing of diesel, but also reduces the diesel-gasoline ratio of the refinery and improves the economic and social benefits of the enterprise.

The separated non-aromatic hydrocarbons can be used as high-quality diesel blending components and high-quality olefin production-increasing raw materials; while the high-purity aromatic hydrocarbons can be used as high-quality aromatic hydrocarbon solvents or high-quality BTX (benzene, toluene, xylene) production-increasing raw materials. Solve the contradiction between excess oil production capacity and insufficient chemical production capacity, while achieving classified management of diesel components. This is of great significance not only for my country's petrochemical industry to improve the quality and efficiency of oil products, but also to promote industrial transformation and upgrading.

Industrial separation technologies for mixed aromatic components mainly include precision distillation, membrane separation technology, adsorption separation technology, etc. The precision distillation method uses the difference in boiling point of each component to achieve separation and purification, but its separation fraction is narrow and the process is complex. The operation is difficult. Membrane separation technology mainly uses the difference in diffusion coefficients of different components when they pass through the membrane to separate mixed components. Although it has the advantages of low energy consumption and simple process, the production of separation membranes is more complex and costly, and it is difficult to achieve high-pass. The balance between quantity and high selectivity restricts its industrial application. CN107774143A discloses a hydrotalcite tubular hybrid membrane for separating aromatic hydrocarbons/alkanes and a preparation method thereof. The hybrid membrane prepared by it is used for the separation of aromatic hydrocarbons/alkanes in the field of pervaporation. The performance of the pervaporation membrane is: the permeation flux is 400-600g·m ^-2 ·h ^-1 , the toluene content in the permeate liquid is about 70%, and the separation factor is 2-5. It shows good separation performance and has potential application prospects.

Using existing adsorption separation technology, there are problems such as low product purity of aromatic hydrocarbon components and non-aromatic hydrocarbon components, large amounts of desorbent, and low yield of target products. CN109022020A discloses a method for multi-component adsorption and separation of diesel fuel. The aromatic hydrocarbon adsorbent metal-modified MCM-41 molecular sieve is used to adsorb monocyclic and polycyclic aromatic hydrocarbon components to obtain naphthenic hydrocarbon components, and methylcyclohexane is used as the desorbent. The adsorption temperature of this method is 25-150°C, the adsorption pressure is 0.1-2.0MPa, the desorption temperature is 50-200°C, and the desorption pressure is 0.1-1.5MPa. After adsorption and separation, the paraffin content of the paraffin component is more than 85%. The naphthenic hydrocarbon content in the naphthenic hydrocarbon component is more than 95%, the monocyclic aromatic hydrocarbon content in the monocyclic aromatic hydrocarbon component is more than 95%, and the polycyclic aromatic hydrocarbon content in the polycyclic aromatic hydrocarbon component is more than 90%. CN 109022020B uses a combined extraction and adsorption method to separate aromatic hydrocarbons, in which silica gel is used as the adsorbent and alkylbenzene is used as the desorbent to adsorb and separate aromatic hydrocarbon compounds. This adsorption method has an adsorption temperature of 60 to 100°C and a desorption temperature of 10 to 50°C. The desorption time is 20 to 60 minutes. After adsorption and separation, the aromatic hydrocarbon content of the diesel component is reduced to less than 20%, and the aromatic hydrocarbon content of the separated aromatic hydrocarbon component is greater than 90%.

At present, there are few reports on the fine separation of mixed aromatic components in oil products. The non-aromatic components separated by the adsorption separation technology in the present invention can not only be used as high-quality diesel blending components, but also can be used as high-quality olefin production-increasing raw materials. Of course, they can also be directly sold as non-aromatic solvents. The separated high-purity monocyclic aromatic hydrocarbons can be used as high-quality raw materials to lighten heavy aromatic hydrocarbons; polycyclic aromatic hydrocarbons can be blended into high-aromatic solvent naphtha for sale.

Contents of the invention

In view of this, in order to overcome the shortcomings of the prior art, the present invention provides a method for achieving fine separation of multi-component aromatics in oil based on a simulated moving bed process. This method uses activated carbon, molecular sieves or metal modified materials as aromatic hydrocarbon adsorbents, and achieves fine separation of monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons and tricyclic aromatic hydrocarbons through three simulated moving bed devices. The invention has the characteristics of environmental protection, no pollution, mild reaction conditions, low investment, low energy consumption and easy control.

The technical solution of the present invention is as follows.

A method for achieving fine separation of aromatics in oil based on a combined simulated moving bed process, including a combined simulated moving bed separation method and functional adsorption materials in the bed, and each adsorption column is filled with functional adsorption materials. The functional adsorption materials include at least one of activated carbon, molecular sieves or metal modified materials;

The steps are: using three simulated moving bed adsorption devices connected in series, where the three simulated moving bed devices are all four-zone simulated moving bed adsorption devices, including adsorption I zone, isolation IV zone, desorption III zone and refining II zone. Each adsorption bed contains inlet and outlet pipelines and periodic switching valves, each of which forms a closed loop through a circulation pump (see Figure 1).

The aromatic hydrocarbon-containing oil first passes through a simulated moving bed to adsorb and separate the aromatic hydrocarbon components in the oil to obtain high-purity mixed aromatic hydrocarbons and non-aromatic hydrocarbons. Then the high-purity mixed aromatic components pass through the second and third simulated moving bed devices to adsorb monocyclic, bicyclic and tricyclic aromatic components respectively, thereby efficiently achieving fine separation of multi-component aromatics in oil products.

Further, the simulated moving bed device is composed of adsorption I zone, isolation IV zone, desorption zone III and refining zone II along the direction of material flow. Each zone is assigned at least one adsorption column; the adsorption zone I uses aromatic hydrocarbon adsorbent. It adsorbs aromatic hydrocarbon components in oil products to obtain high-purity mixed aromatic hydrocarbons and non-aromatic hydrocarbons. Each adsorption column is equipped with a multi-position valve. The multi-position valve contains four feed and inlet pipelines, corresponding to raw materials, desorbent, and extraction. liquid and raffinate; periodically switch the valves of each material stream to simulate the continuous adsorption-regeneration process of the moving bed.

Further, the oil to be treated is at least one of catalytic gasoline, catalytic diesel, coked gasoline, coked diesel, straight-run gasoline, and straight-run diesel.

Furthermore, the adsorption separation method can achieve a change in the order of aromatic separation by changing the adsorbent type and feed position of the adsorption bed, including two processes: separating light components (monocyclic aromatics) first and separating heavy components (tricyclic aromatics) first.

Further, the aromatic hydrocarbon adsorbent is a porous carbon material or a metal modified molecular sieve material, and the modified metal is one or more of Mg, Ni, Cu, K, Co, Cr, and Fe, and the content is 0.5 to 10 wt%. , the molecular sieve is one of NaY, 13X, MCM-41, and ZSM-5; the tricyclic aromatic hydrocarbon adsorbent is porous carbon material or its metal modified material, and the modified metal used is Mg, Ni, Cu, Mn, Fe, One or more of Cr and Zn, the content is 0.5 to 10wt%; the monocyclic or bicyclic aromatic hydrocarbon adsorbent is one of metal modified molecular sieve materials or porous carbon materials, and the metal ions are Mg, Ca, Ba , any one or two metal ions among Cu, Ni, Mn, Zn, Fe, Co and Cr, the content is 0.5~10wt%.

Furthermore, the combination of aromatic hydrocarbon adsorbents in each simulated moving bed can adjust the aromatic hydrocarbon separation performance; that is, by changing the adsorbent type and feed position of the adsorption bed, the aromatic hydrocarbon separation sequence can be changed. For example, the adsorption zone passes through the aromatic hydrocarbon adsorbent. The light component (single-ring aromatic hydrocarbons) and the heavy component (tricyclic aromatic hydrocarbons) are separated first, and the desorbent is regenerated in the analysis zone to obtain the aromatic components. The regenerated adsorbent is recycled again through the refining zone, and finally achieves Fine separation of aromatics in oil products.

Among them, the desorbent used in the desorption zone is at least one of toluene, methylcyclohexane, ethylbenzene, n-dodecane, ethylnaphthalene, and cyclohexane.

Further, the adsorbent bed temperature in the adsorption zone I is 20-150°C, and the adsorption pressure is 0.1-2.0MPa; during regeneration in the desorption zone III, the bed temperature is 40-150°C, the regeneration pressure is 0.1-2.0MPa, and the cycle is switched The time is 200~1500s, the mass flow rate ratio of mixed aromatic hydrocarbon raw material and desorbent is 1:1.5~1:4; the volume flow rate ratio of raw material and circulation amount is 1:2~1:5.

Furthermore, the order of adsorbing and separating materials is based on the adsorbent types of the second and third adsorption beds. The separation order includes separating heavy component tricyclic aromatic hydrocarbons first and separating light component monocyclic aromatic hydrocarbons first.

The application of a high-efficiency porous carbon-based adsorbent in adsorbing and separating mixed aromatic hydrocarbons in oil products is used to recover aromatic hydrocarbons from aromatic hydrocarbon-rich oil products; or the use is to remove aromatic hydrocarbons from aromatic hydrocarbon-rich oil products.

Compared with the prior art, the present invention has the following advantages:

1. The present invention adopts an efficient and environmentally friendly simulated moving bed process, and can adsorb and separate the mixed aromatic components in the oil through three SMB devices. The adsorption and regeneration processes of the present invention are performed at low temperature and low pressure, and the reaction conditions are mild. It has the advantages of environmental protection, no pollution, low energy consumption and easy control.

2. By adjusting the type of adsorption material in the adsorption bed, the aromatic hydrocarbon separation sequence can be adjusted, which greatly improves the adaptability of the process to raw materials. The high-purity monocyclic aromatic hydrocarbons obtained through separation can be used as high-quality raw materials to lighten heavy aromatic hydrocarbons; polycyclic aromatic hydrocarbons can be blended into high-aromatic solvent naphtha for sale. The purpose is achieved through the following technical solutions.

Description of drawings

Figure 1 is a schematic diagram of a simulated moving bed adsorption device containing four functional areas;

Figure 2 is a simplified process flow diagram for the fine separation of multi-component aromatics in oil;

Figure 3 is a schematic diagram of a 24-column simulated moving bed adsorption separation device.

Detailed ways

The invention relates to a method for fine separation of multi-component aromatic hydrocarbons, which includes a metal-modified adsorbent and relevant process parameters for simulated moving bed adsorption and separation of aromatic hydrocarbons. The metal-modified adsorbent and the carrier adopt activated carbon, molecular sieves, alumina, and dioxide. A kind of silicon, the modified metal used is one or more of Mg, Ni, Cu, Mn, Fe, Cr, Zn, and Ca.

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described here are only used to explain the present invention and do not limit the scope of the present invention.

With reference to Figure 3, the aromatic hydrocarbon-rich oil and three desorbents are connected to 24 adsorption towers through rotary valves. The adsorption tower can be divided into three functional areas through the switching sequence of the valves, namely, the dearomatization area, the heavy aromatic hydrocarbons area, and the dearomatic area. Light aromatics zone, as shown in Figure 2. Each functional area consists of 8 towers, which serve as areas 1-4 of the moving bed, as shown in Figure 1. The three functional areas are connected upstream and downstream through two pipelines: light aromatic liquid and heavy aromatic liquid. Among them, the liquid extracted from the dearomatization zone is directly connected to the lower aromatic oil pipeline for discharge. The eluate from the dearomatization zone and the extraction liquid from the heavy aromatic hydrocarbons or light aromatic hydrocarbons removal zone are connected to two light/heavy aromatic hydrocarbon liquid pipelines, and then enter the subsequent separation zone through valve control. Finally, the separated products pass through the monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons and tricyclic aromatic hydrocarbons product lines and enter the downstream distillation unit for distillation and separation to obtain a series of high-purity aromatic hydrocarbon products. In addition, the number of adsorption towers can be expanded according to actual conditions, and the functions of each area remain unchanged.

The following implementation examples will further illustrate the present invention.

The diesel used in the embodiment is hydrogenated diesel from a certain refinery. Its aromatic hydrocarbon content is 10% to 70% and contains toluene, ethylnaphthalene, hexadecane, dodecylbenzene, naphthalene, tetrahydronaphthalene, phenanthrene, etc. Various compounds. The content of polycyclic aromatic hydrocarbons was determined using gas chromatography (GC) and chromatography-mass spectrometry (GC-MS).

Example 1

(1) The aromatic hydrocarbon adsorbent in SMB1 is a porous carbon material derived from coconut shell. The tricyclic aromatic hydrocarbon adsorbent in SMB2 is a metal-modified wood activated carbon material. The modified metal used is Ni, and the Ni(NO ₃ ) ₂ content is 0.5wt%. The bicyclic aromatic hydrocarbon adsorbent in SMB3 adopts metal-modified Y molecular sieve material. The metal ions are Mg and Ca. The MgO content is 0.5wt% and the CaO content is 0.5wt%.

(2) The mass flow rate ratio of mixed aromatic hydrocarbon raw material and desorbent is 1:2; the volume flow rate ratio of raw material and circulation amount is 1:3, and the switching time is 400s.

(3) Adsorbent evaluation: Hydrogenated catalytic diesel from a refinery was used as raw material, and the aromatic component mass fraction was 30%. The adsorbents were loaded into three simulated moving bed devices, and the adsorption separation was a countercurrent simulated moving bed adsorption separation process. , the adsorption separation temperature is 40°C, and the desorbent uses cyclohexane and ethylbenzene, of which the ethylbenzene mass fraction is 60%. The aromatic-rich oil first passes through a simulated moving bed SMB1 to adsorb and separate the aromatic components in the diesel to obtain high-purity mixed aromatic hydrocarbons and non-aromatic hydrocarbons. Then the high-purity mixed aromatic components pass through the simulated moving bed device SMB2 to adsorb the heavy aromatic hydrocarbons with three rings and above to obtain high-purity heavy aromatic components with three rings and above and light aromatics (monocyclic and bicyclic); or Adsorb monocyclic aromatic hydrocarbons to obtain high-purity monocyclic aromatic hydrocarbon components and polycyclic aromatic hydrocarbons (bicyclic and tricyclic). If the light aromatic hydrocarbons (monocyclic and bicyclic aromatic hydrocarbons) components enter the simulated moving bed SMB3, the bicyclic aromatic hydrocarbons in it will be adsorbed, and then high-purity bicyclic aromatic hydrocarbons raffinate and monocyclic aromatic hydrocarbons extract will be obtained; if polycyclic aromatic hydrocarbons (bicyclic and tricyclic aromatic hydrocarbons) The cyclic aromatic hydrocarbons) component enters the simulated moving bed SMB3 and adsorbs the tricyclic aromatic hydrocarbons therein, thereby obtaining high-purity tricyclic aromatic hydrocarbon raffinate and bicyclic aromatic hydrocarbon raffinate. After three simulations, the moving bed device efficiently achieves fine separation of multi-component aromatics in oil. Finally, high-purity monocyclic, bicyclic and tricyclic aromatic hydrocarbon components are obtained. The separation process adopts a 24-tower model as shown in Figure 3. The specific zones are 8-8-8. The distribution and evaluation results of the adsorption towers in each zone are shown in Table 1.

Example 2

(1) The aromatic hydrocarbon adsorbent in SMB1 uses metal-modified ZSM-5 material. The modified metal is Mg, in which the Mg(NO ₃ ) ₂ content is 0.5 wt%. The tricyclic aromatic hydrocarbon adsorbent in SMB2 is coconut shell activated carbon material. , the bicyclic aromatic hydrocarbon adsorbent in SMB3 uses metal-modified X molecular sieve material. The metal ions are Cu and Ni, where the Cu(NO ₃ ) ₂ content is 1wt% and the Ni(NO ₃ ) ₂ content is 1wt%.

(2) The mass flow rate ratio of mixed aromatic hydrocarbon raw material and desorbent is 1:1.5; the volume flow rate ratio of raw material and circulation amount is 1:3, and the switching time is 200s.

(3) Adsorbent evaluation: Hydrogenated catalytic diesel from a refinery was used as raw material, and the aromatic component mass fraction was 40%. The adsorbents were loaded into three simulated moving bed devices, and the adsorption separation was a countercurrent simulated moving bed adsorption separation process. , the adsorption separation temperature is 60°C, and the desorbent uses methylcyclohexane and ethylbenzene, of which the ethylbenzene mass fraction is 80%. The aromatic-rich oil first passes through SMB1 to adsorb and separate the aromatic components in the diesel to obtain high-purity mixed aromatic hydrocarbons and non-aromatic hydrocarbons. Then the high-purity mixed aromatic components pass through SMB2 again to adsorb heavy aromatic hydrocarbons with three rings and above, and obtain high-purity heavy aromatic hydrocarbon components with three rings and above and light aromatics (monocyclic and bicyclic); or adsorb single-ring aromatic hydrocarbons. , obtaining high-purity monocyclic aromatic hydrocarbon components and polycyclic aromatic hydrocarbons (bicyclic and tricyclic). If the light aromatic hydrocarbons (monocyclic and bicyclic aromatic hydrocarbons) components enter the simulated moving bed SMB3, the bicyclic aromatic hydrocarbons in it will be adsorbed, and then high-purity bicyclic aromatic hydrocarbons raffinate and monocyclic aromatic hydrocarbons extract will be obtained; if polycyclic aromatic hydrocarbons (bicyclic and tricyclic aromatic hydrocarbons) The cyclic aromatic hydrocarbons) component enters the simulated moving bed SMB3 and adsorbs the tricyclic aromatic hydrocarbons therein, thereby obtaining high-purity tricyclic aromatic hydrocarbon raffinate and bicyclic aromatic hydrocarbon raffinate. After three simulations of the moving bed device, the fine separation of multi-component aromatics in diesel is efficiently achieved. Finally, high-purity monocyclic, bicyclic and tricyclic aromatic hydrocarbon components are obtained. The separation process adopts a 24-tower model as shown in Figure 3. The specific zones are 8-8-8. The distribution and evaluation results of the adsorption towers in each zone are shown in Table 1.

Example 3

(1) The aromatic hydrocarbon adsorbent in SMB1 uses metal-modified NaY material. The modified metals are Co and Ba. The content of Co(NO ₃ ) ₂ is 2wt% and the content of Ba(NO _{3 ) 2 is 2wt%. The content of Ba(NO 3} ) ₂ in SMB2 is 2wt%. The tricyclic aromatic hydrocarbon adsorbent is metal-modified nutshell activated carbon material. The modified metal used is Mg, of which the Mg(NO ₃ ) ₂ content is 1.5 wt%. The bicyclic aromatic hydrocarbon adsorbent in SMB3 uses metal-modified MCM-41 molecular sieve material. , the metal ion used is Cu, and the CuO content is 1.5wt%.

(2) The mass flow rate ratio of mixed aromatic hydrocarbon raw material and desorbent is 1:2; the volume flow rate ratio of raw material and circulation amount is 1:4, and the switching time is 500s.

(3) Adsorbent evaluation: Hydrogenated catalytic diesel from a refinery was used as raw material, and the aromatic component mass fraction was 50%. The adsorbents were loaded into three simulated moving bed devices, and the adsorption separation was a countercurrent simulated moving bed adsorption separation process. , the adsorption separation temperature is 80°C, and pure ethylbenzene is used as the desorbent. The aromatic-rich oil first passes through SMB1 to adsorb and separate the aromatic components in the diesel to obtain high-purity mixed aromatic hydrocarbons and non-aromatic hydrocarbons. Then the high-purity mixed aromatic components pass through SMB2 again to adsorb heavy aromatic hydrocarbons with three rings and above, and obtain high-purity heavy aromatic hydrocarbon components with three rings and above and light aromatics (monocyclic and bicyclic); or adsorb single-ring aromatic hydrocarbons. , obtaining high-purity monocyclic aromatic hydrocarbon components and polycyclic aromatic hydrocarbons (bicyclic and tricyclic). If the light aromatic hydrocarbons (monocyclic and bicyclic aromatic hydrocarbons) components enter the simulated moving bed SMB3, the bicyclic aromatic hydrocarbons in it will be adsorbed, and then high-purity bicyclic aromatic hydrocarbons raffinate and monocyclic aromatic hydrocarbons extract will be obtained; if polycyclic aromatic hydrocarbons (bicyclic and tricyclic aromatic hydrocarbons) The (cyclic aromatic hydrocarbons) component enters the simulated moving bed SMB3 and adsorbs the tricyclic aromatic hydrocarbons therein, thereby obtaining high-purity tricyclic aromatic hydrocarbon raffinate and bicyclic aromatic hydrocarbon raffinate. After three simulations of the moving bed device, the fine separation of multi-component aromatics in diesel is efficiently achieved. Finally, high-purity monocyclic, bicyclic and tricyclic aromatic hydrocarbon components are obtained. The separation process adopts a 24-tower model as shown in Figure 3. The specific zones are 8-8-8. The distribution and evaluation results of the adsorption towers in each zone are shown in Table 1.

Example 4

(1) The aromatic hydrocarbon adsorbent in SMB1 is a metal-modified molecular sieve material. The modified metal is Cu, in which the Cu( _NO3 ) ₂ content is 3wt%. The tricyclic aromatic hydrocarbon adsorbent in SMB2 is a metal-modified wood activated carbon material. The modified metal is Ni, where the Ni(NO ₃ ) ₂ content is 3wt%. The bicyclic aromatic hydrocarbon adsorbent in SMB3 adopts metal-modified X molecular sieve material. The metal ions are Ca and Ba, where the CaO content is 2.5wt%. The BaO content is 2.5wt%.

(2) The mass flow rate ratio of mixed aromatic hydrocarbon raw material and desorbent is 1:2; the volume flow rate ratio of raw material and circulation amount is 1:1.5, and the switching time is 1200s.

(3) Adsorbent evaluation: Hydrogenated catalytic diesel from a refinery was used as raw material, and the aromatic component mass fraction was 60%. The adsorbents were loaded into three simulated moving bed devices, and the adsorption separation was a countercurrent simulated moving bed adsorption separation process. , the adsorption separation temperature is 80°C, and the desorbent uses methylcyclohexane and toluene, of which the mass fraction of toluene is 80%. The aromatic-rich oil first passes through SMB1 to adsorb and separate the aromatic components in the diesel to obtain high-purity mixed aromatic hydrocarbons and non-aromatic hydrocarbons. Then the high-purity mixed aromatic components pass through SMB2 again to adsorb heavy aromatic hydrocarbons with three rings and above, and obtain high-purity heavy aromatic hydrocarbon components with three rings and above and light aromatics (monocyclic and bicyclic); or adsorb single-ring aromatic hydrocarbons. , obtaining high-purity monocyclic aromatic hydrocarbon components and polycyclic aromatic hydrocarbons (bicyclic and tricyclic). If the light aromatic hydrocarbons (monocyclic and bicyclic aromatic hydrocarbons) components enter the simulated moving bed SMB3, the bicyclic aromatic hydrocarbons in it will be adsorbed, and then high-purity bicyclic aromatic hydrocarbons raffinate and monocyclic aromatic hydrocarbons extract will be obtained; if polycyclic aromatic hydrocarbons (bicyclic and tricyclic aromatic hydrocarbons) The cyclic aromatic hydrocarbons) component enters the simulated moving bed SMB3 and adsorbs the tricyclic aromatic hydrocarbons therein, thereby obtaining high-purity tricyclic aromatic hydrocarbon raffinate and bicyclic aromatic hydrocarbon raffinate. After three simulations of the moving bed device, the fine separation of multi-component aromatics in diesel is efficiently achieved. Finally, high-purity monocyclic, bicyclic and tricyclic aromatic hydrocarbon components are obtained. The separation process adopts a 24-tower model as shown in Figure 3. The specific zones are 8-8-8. The distribution and evaluation results of the adsorption towers in each zone are shown in Table 1.

Example 5

(1) The aromatic hydrocarbon adsorbent in SMB1 is a porous carbon material derived from nut shells. The tricyclic aromatic hydrocarbon adsorbent in SMB2 is a metal-modified coconut shell activated carbon material. The modified metal is Zn, and the Zn(NO ₃ ) ₂ content is 5wt%, the bicyclic aromatic hydrocarbon adsorbent in SMB3 uses metal-modified Y molecular sieve material, the modified metal is Ni, and the Ni(NO ₃ ) ₂ content is 5wt%.

(2) The mass flow rate ratio of mixed aromatic hydrocarbon raw material and desorbent is 1:2.5; the volume flow rate ratio of raw material and circulation amount is 1:3.5, and the switching time is 600s.

(3) Adsorbent evaluation: Hydrogenated catalytic diesel from a refinery was used as raw material, and the aromatic component mass fraction was 70%. The adsorbents were loaded into three simulated moving bed devices, and the adsorption separation was a countercurrent simulated moving bed adsorption separation process. , the adsorption separation temperature is 100°C, and the desorbent uses n-hexadecane and ethylbenzene, of which the ethylbenzene mass fraction is 60%. The aromatic-rich oil first passes through SMB1 to adsorb and separate the aromatic components in the diesel to obtain high-purity mixed aromatic hydrocarbons and non-aromatic hydrocarbons. Then the high-purity mixed aromatic components pass through SMB2 again to adsorb heavy aromatic hydrocarbons with three rings and above, and obtain high-purity heavy aromatic hydrocarbon components with three rings and above and light aromatics (monocyclic and bicyclic); or adsorb single-ring aromatic hydrocarbons. , obtaining high-purity monocyclic aromatic hydrocarbon components and polycyclic aromatic hydrocarbons (bicyclic and tricyclic). If the light aromatic hydrocarbons (monocyclic and bicyclic aromatic hydrocarbons) components enter the simulated moving bed SMB3, the bicyclic aromatic hydrocarbons in it will be adsorbed, and then high-purity bicyclic aromatic hydrocarbons raffinate and monocyclic aromatic hydrocarbons extract will be obtained; if polycyclic aromatic hydrocarbons (bicyclic and tricyclic aromatic hydrocarbons) The cyclic aromatic hydrocarbons) component enters the simulated moving bed SMB3 and adsorbs the tricyclic aromatic hydrocarbons therein, thereby obtaining high-purity tricyclic aromatic hydrocarbon raffinate and bicyclic aromatic hydrocarbon raffinate. After three simulations of the moving bed device, the fine separation of multi-component aromatics in diesel is efficiently achieved. Finally, high-purity monocyclic, bicyclic and tricyclic aromatic hydrocarbon components are obtained. The separation process adopts a 24-tower model as shown in Figure 3. The specific zones are 8-8-8. The distribution and evaluation results of the adsorption towers in each zone are shown in Table 1.

Table 1 Analysis data of multi-component aromatic hydrocarbons in diesel fuel adsorbed and separated

In order to further illustrate the excellence of the solution of this application, the following comparative examples are also made in this application.

Comparative example 1

Compared with Example 1, the difference in Comparative Example 1 is that the aromatic hydrocarbon adsorbent in SMB1 uses unmodified molecular sieve materials, and other conditions are the same as Example 1. It is found that the aromatic-rich oil first passes through a simulated moving bed SMB1. , the aromatic hydrocarbon content in the extracted liquid is higher than 40%, and the aromatic hydrocarbon content in the eluent is less than 80%, and aromatic hydrocarbons and aromatic hydrocarbon components cannot be well separated. This is because molecular sieve materials without metal modification have weak adsorption force on aromatic hydrocarbon components and poor selectivity, making it difficult to achieve lumped adsorption of aromatic hydrocarbons.

Comparative example 2

Compared with Example 2, the difference of Comparative Example 2 is that the mass flow rate ratio of mixed aromatic hydrocarbon raw material and desorbent is 1:5, and other conditions are the same as Example 2. It is found that after the aromatic-rich oil first passes through the simulated moving bed three times, The contents of the corresponding monocyclic, bicyclic and tricyclic aromatic hydrocarbon components in the three products are 74%, 66% and 79% respectively, making it impossible to achieve fine separation of multi-component aromatic hydrocarbons in oil products. This is because at too high a flow rate, the fluid passes through the adsorption column for a short time and cannot fully contact and separate the components in the mixture. At the same time, high-speed flow will also make it difficult for the components in the mixture to stratify stably in the adsorption column, resulting in increased mixing and lower separation, making it difficult to achieve fine separation of aromatics.

Comparative example 3

Compared with Example 3, the difference in Comparative Example 3 is that the tricyclic aromatic hydrocarbon adsorbent in SMB2 is a metal-modified mesoporous silica material, and the bicyclic aromatic hydrocarbon adsorbent in SMB3 is a molecular sieve material. Other conditions are the same as those in the Examples 3 is the same. It was found that after changing the adsorbents in SMB2 and SMB3, the purity of the aromatic hydrocarbon-rich oil products after passing through the simulated moving bed for three times was significantly reduced by more than 30%. This is because unmodified molecular sieves and metal-modified silica have similar adsorption forces for tricyclic and bicyclic aromatic hydrocarbons and have poor selectivity, making it difficult to achieve fine separation of aromatic hydrocarbons.

The above-mentioned specific embodiments describe in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above-mentioned are only the most preferred embodiments of the present invention and are not intended to limit the present invention. However, any implementation without departing from the present invention As for the content of the technical solution, any simple modifications, equivalent changes and modifications made to the above implementation based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. A method for realizing fine separation of aromatic hydrocarbon in oil based on a combined simulated moving bed process is characterized by comprising a separation method of the combined simulated moving bed and functional adsorption materials in a bed layer, wherein each adsorption column is filled with the functional adsorption materials, and the functional adsorption materials comprise more than one of active carbon, molecular sieve or metal modified materials;

the separation method of the combined simulated moving bed comprises the following steps: three simulated moving bed adsorption devices which are mutually connected in series are adopted, wherein the three simulated moving bed devices are four-zone simulated moving bed adsorption devices, each simulated moving bed device comprises an adsorption I zone, an isolation IV zone, a desorption III zone and a refining II zone, each adsorption bed layer comprises a feeding and discharging pipeline and a periodic switching valve, and each adsorption bed layer forms a closed loop through a circulating pump;

the method comprises the specific processes that firstly, mixed aromatic hydrocarbon materials are introduced into a first simulated moving bed adsorption device, adsorption columns of the first simulated moving bed adsorption device are connected end to end side by side and form a closed loop through connection of a circulating pump, the simulated moving bed adsorption device is divided into four areas, an adsorption I area, an isolation IV area, a desorption III area and a refining II area are sequentially arranged along the material flow direction, and at least 1 adsorption column is distributed in each area; the adsorption I zone adopts an aromatic hydrocarbon adsorbent to adsorb aromatic hydrocarbon components in oil products, so that two major categories of high-purity mixed aromatic hydrocarbon and non-aromatic hydrocarbon are obtained; sequentially introducing the high-purity mixed aromatic hydrocarbon component into a second simulated moving bed device and a third simulated moving bed device for adsorption separation, wherein each adsorption column is arranged the same as the first simulated moving bed device, but the aromatic hydrocarbon adsorbents adopted in the adsorption I area are different, so that high-purity monocyclic, bicyclic and tricyclic aromatic hydrocarbon components can be finally obtained, and fine separation is realized; the adsorbents in the second and third simulated moving bed devices are tricyclic aromatic hydrocarbon adsorbents and monocyclic or bicyclic aromatic hydrocarbon adsorbents.

2. The method for realizing fine separation of aromatic hydrocarbon in oil based on combined simulated moving bed technology as claimed in claim 1, wherein the oil to be treated is more than one of catalytic gasoline, catalytic diesel oil, coker gasoline, coker diesel oil, straight-run gasoline and straight-run diesel oil.

3. The method for realizing fine separation of aromatic hydrocarbon in oil based on combined simulated moving bed process as claimed in claim 1, wherein the simulated moving bed device is sequentially provided with an adsorption zone I, an isolation zone IV, a desorption zone III and a refining zone II along the material flow direction, and each zone is at least provided with 1 adsorption column; the adsorption I zone adopts an aromatic hydrocarbon adsorbent to adsorb aromatic hydrocarbon components in oil products, so that two major categories of high-purity mixed aromatic hydrocarbon and non-aromatic hydrocarbon are obtained; each adsorption column is provided with a multi-position valve, and the multi-position valve comprises four feed and discharge pipelines which are correspondingly used as raw materials, desorbent, extract and raffinate; and periodically switching each material valve to realize the continuous adsorption-regeneration process of the simulated moving bed.

4. The method for realizing fine separation of aromatic hydrocarbon in oil based on combined simulated moving bed technology as claimed in claim 1, wherein the aromatic hydrocarbon adsorbent is porous carbon material or metal modified molecular sieve material, the modified metal is more than one of Mg, ni, cu, K, co, cr, fe, and the content is 0.5-10wt%; the molecular sieve is one of NaY, 13X, MCM-41 and ZSM-5; the tricyclic aromatic hydrocarbon adsorbent is a porous carbon material or a metal modified material thereof, wherein the modified metal is one or more of Mg, ni, cu, mn, fe, cr, zn, and the content is 0.5-10wt%; the monocyclic or bicyclic aromatic hydrocarbon adsorbent is one of a metal modified molecular sieve material or a porous carbon material, and the metal ions are one or two metal ions in Mg, ca, ba, cu, ni, mn, zn, fe, co, cr, and the content is 0.5-10wt%.

5. The method for realizing fine separation of aromatic hydrocarbon in oil based on combined simulated moving bed process as claimed in any one of claims 1-4, wherein the combination of aromatic hydrocarbon adsorbents in each simulated moving bed can realize adjustment of aromatic hydrocarbon separation performance; the method comprises the steps that the type and the feeding position of an adsorbent of an adsorption bed layer are changed, the separation sequence of aromatic hydrocarbon can be changed, the adsorption zone firstly separates light components (monocyclic aromatic hydrocarbon) and firstly separates heavy components (tricyclic aromatic hydrocarbon) through the aromatic hydrocarbon adsorbent, the desorption zone is regenerated through a desorber to obtain aromatic hydrocarbon components, the regenerated adsorbent is recycled through a refining zone, and finally, the fine separation of aromatic hydrocarbon in oil products is realized;

wherein, the desorbing agent adopted in the desorption zone is more than one of toluene, methylcyclohexane, ethylbenzene, n-dodecane, ethylnaphthalene and cyclohexane.

6. The method for realizing fine separation of aromatic hydrocarbon in oil based on combined simulated moving bed technology as claimed in claim 1, wherein the temperature of the adsorbent bed in the adsorption zone I is 20-150 ℃ and the adsorption pressure is 0.1-2.0 MPa; the temperature of the bed layer in the desorption III zone is 40-150 ℃ and the regeneration pressure is 0.1-2.0 MPa.

7. The method for realizing fine separation of aromatic hydrocarbon in oil based on combined simulated moving bed process as claimed in claim 3, wherein the periodic switching valve realizes continuous adsorption separation of the simulated moving bed device, and the switching time is 200-1500 s.

8. The method for realizing fine separation of aromatic hydrocarbon in oil based on combined simulated moving bed technology as claimed in claim 1, wherein the mass flow rate ratio of the mixed aromatic hydrocarbon raw material to the desorbent is 1:1.5-1:4; the volume flow rate ratio of the raw materials to the circulation amount is 1:2-1:5.

9. The method for realizing fine separation of aromatic hydrocarbons in oil products based on a combined simulated moving bed process as claimed in claim 1, wherein the order of adsorption separation materials is based on the type of adsorbents of the second and third adsorption beds, and the separation order comprises two kinds of separation of heavy component tricyclic aromatic hydrocarbons and separation of light component monocyclic aromatic hydrocarbons.

10. A method for realizing fine separation of aromatic hydrocarbon in oil products based on combined simulated moving bed technology as claimed in claims 1-9, which is characterized in that the method is applied to aromatic hydrocarbon recovery of aromatic hydrocarbon-rich oil products; or the application is used for removing the aromatic hydrocarbon in the aromatic hydrocarbon-rich oil product.