A diesel dearomatization adsorbent, preparation method and application thereof

Abstract

The application discloses a diesel de-aromatic adsorbent, a preparation method and use thereof. The main component of the adsorbent is silica, and the surface of the adsorbent is modified by using an organic amine. After modification, the adsorbent has good strength, large ignition base bulk density, large specific surface area, large adsorption capacity and fast mass transfer. The modified adsorbent can be applied to a simulated moving bed process to separate aromatic components in diesel oil. The modified adsorbent has a wider application range for raw materials, is not sensitive to sulfur and nitrogen impurities in the raw materials, has enhanced selectivity for aromatic hydrocarbons in diesel oil, and has improved separation performance.

Description

Technical Field

[0001] The present invention relates to a diesel dearomatization adsorbent, a preparation method and application thereof, and more specifically, to the use of a silicon dioxide adsorbent to separate aromatic and alkane components in diesel. Background Art

[0002] my country's refining and chemical industry currently faces significant structural challenges, with overcapacity in oil products, particularly diesel, having reached peak consumption. Domestic refinery utilization rates are less than 80%. With the recent commissioning of several large-scale refining and chemical projects, my country's oil product overcapacity problem is expected to worsen. However, driven by increasing demand for downstream chemical derivatives, domestic demand for aromatics and olefins continues to grow rapidly, resulting in a high degree of external dependence. Therefore, the refining and chemical industry's primary task is to control the rapid growth of refining capacity while developing integrated oil and chemical technologies, adjusting the product mix of refining units, and utilizing excess oil products to increase chemical production, thereby achieving industrial transformation and upgrading. Currently, diesel hydrotreating, LTAG, and RLG technologies are commonly used to convert diesel into gasoline or BTX. However, these technologies often employ a process involving the fragmentation of large molecules and the reconstruction of small molecules, resulting in high hydrogen consumption, low selectivity, harsh reaction conditions, and high operating costs. Therefore, combining the concept of molecular refining, we first use the adsorption separation processing technology to divide the diesel components into aromatics-rich components and alkane-rich components, and then use them separately for chemical utilization. In this way, diesel can be converted into chemical raw materials at a lower cost, providing a new processing route for the transformation and upgrading of refining equipment.

[0003] CN110938459A discloses a method for producing petroleum ether and light white oil from naphtha. The process features a process in which the naphtha is passed through a pre-adsorption unit under low-temperature, low-pressure, and moderate conditions to remove trace colloids and sulfur compounds from the naphtha. A simulated moving bed separation removes aromatics to produce non-aromatic and aromatic-rich components. This method produces petroleum ether and light white oil products that meet standard requirements under non-hydrogenation conditions, while also producing high-octane gasoline blending components as a by-product.

[0004] CN110938465A discloses a method for the multi-component adsorption separation of gasoline. This method involves first feeding the gasoline feedstock into a selective hydrogenation unit and then into a five-zone simulated moving bed apparatus for adsorption separation of saturated hydrocarbons, olefins, and aromatics. The separated saturated hydrocarbons provide a high-quality ethylene feedstock, while the aromatics can be used to produce high-value-added BTX products. This method not only achieves the goal of advanced gasoline processing but also improves the economic and social benefits of the enterprise.

[0005] CN110938458A discloses a method for producing high-quality industrial white oil, comprising three process units: raw material pretreatment, simulated moving bed adsorption separation, and desorbent distillation recovery. The raw material is pretreated, alkaline nitride and oxide impurities are removed by adsorption, and then subjected to simulated moving bed adsorption separation to obtain extracted oil and raffinate oil. High-quality white oil is then obtained through distillation separation. The adsorbent used is a mesoporous silica material modified with an aromatic group organosilicon compound. The white oil produced has a low aromatic content and high quality. However, the raw material used in this process is hydrorefined diesel. If non-hydrogenated diesel can be directly processed, production costs can be further reduced.

[0006] CN111054313A discloses an aromatic hydrocarbon adsorbent for white oil refining and a preparation method thereof. The material is prepared by functionalizing the surface of a mesoporous silica material with aromatic hydrocarbon groups. Aromatic hydrocarbon group chlorosiliconates are dissolved in an organic solvent and then impregnated with a carrier silica. The modified adsorbent is used in an aromatic hydrocarbon adsorption and separation process. During the white oil refining process, the aromatic hydrocarbon content of the product is 2.2 to 3.7% by mass, and high-quality white oil is produced at a low cost. However, the examples of this patent do not include detailed physical property measurements of the adsorbent material. The sulfur content of the raw materials involved in the examples is less than 10 μg / g, and the effect of using raw materials with high sulfur and nitrogen contents is not discussed.

[0007] CN109022020A discloses a method for the adsorption separation of multiple components of diesel. The diesel raw material first enters a simulated moving bed device to selectively adsorb the paraffins in the diesel to obtain cycloalkane and aromatic components. The cycloalkane and aromatic components then enter a second simulated moving bed and are separated by an aromatic adsorbent to obtain cycloalkane components and aromatic components, ultimately achieving the separation of paraffins, cycloalkanes, monocyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons in diesel.

[0008] CN107189816B discloses a combined process for maximizing the production of light aromatics from hydrogenated diesel. The process includes: the hydrogenated diesel entering an adsorption separation unit to separate cycloalkanes, paraffins, and aromatic components; the cycloalkanes entering a dehydrogenation reactor to obtain a dehydrogenated product rich in aromatics; the dehydrogenated product entering a second adsorption tower to obtain an aromatics-rich component; and the two aromatic components entering a heavy aromatics conversion reactor to obtain a BTX-rich light aromatics product. Although this method can maximize the production of light aromatics, it requires two sets of adsorption towers, resulting in large equipment investment and complex control.

[0009] CN106244225A discloses a simulated moving bed adsorption separation method for achieving efficient separation of heavy aromatic hydrocarbons. Multiple bed layers are provided in the simulated moving bed. By changing the position of different materials entering or exiting the adsorption tower bed layer, the material and the adsorbent are caused to move relative to each other, thereby achieving adsorption, purification and desorption of C9+ heavy aromatic hydrocarbons, and ultimately achieving the separation of aromatic hydrocarbons and non-aromatic hydrocarbons in the raw materials. Through efficient matching of the adsorption bed layers, the separation of monocyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons can also be achieved.

[0010] In summary, the current use of simulated moving beds to separate diesel and heavy aromatic components still has problems such as restrictions on the sulfur and nitrogen content of the raw materials, and the need for hydrofining before entering the adsorption separation device. Summary of the Invention

[0011] The object of the present invention is to provide a diesel dearomatization adsorbent having good strength, high basic bulk density, large specific surface area, large adsorption capacity and fast mass transfer.

[0012] The present invention provides a diesel dearomatization adsorbent, the main component of the adsorbent is silicon dioxide, and the adsorbent surface is modified using an organic amine. The modified adsorbent has a carbon content of 5 to 15% by mass, preferably 6 to 12%, a nitrogen content of 1 to 10% by mass, preferably 2 to 6%, a C / N ratio of not less than 2.0, preferably 2.0 to 2.5, and a silicon dioxide content of 80 to 95% by mass, preferably 85 to 92% by mass, based on the total mass of the adsorbent.

[0013] In the infrared spectrum, the NH stretching vibration peak of the amino group is between 1300 and 1600 cm -1 The stretching vibration peak of the C-H bond is between 2800 and 3000 cm -1 , with a specific surface area of ​​500-800m 2 / g, the micropore surface area accounts for at least 75% of the total surface area, and the pore volume is 0.1-1cm 3 / g, pore size of 1 to 10 nm, toluene adsorption capacity of not less than 300 mg / g, under a pressure of 250N, the adsorbent breakage rate is not more than 2% by mass, and the calcined bulk density at 200°C is not less than 0.76 mg / mL.

[0014] The present invention also provides a method for preparing a diesel dearomatization adsorbent, comprising:

[0015] S1, using water glass and sulfuric acid as raw materials to synthesize silica sol;

[0016] S2, silica sol is washed with water, diluted and beaten, spray-dried and air-granulated to form small spherical particles;

[0017] S3. Pre-acidify the surface of the adsorbent particles, wash them until they are neutral, and dry them for later use.

[0018] S4. Stirring the pre-acidified adsorbent particles with an organic amine solution to react, thereby obtaining an amino-modified adsorbent.

[0019] The present invention also provides a method for dearomatizing diesel, which comprises applying the adsorbent of the present invention to a diesel adsorption separation process to separate aromatic components in the diesel.

[0020] After the adsorbent of the present invention is modified with amino groups, its selectivity for aromatic components is enhanced and its selectivity for non-aromatic components is weakened. Therefore, the adsorbent can not only adsorb and separate aromatic and alkane components in diesel, but also separate sulfur and nitrogen substances in diesel. Therefore, the adsorbent modified with amino groups can broaden the applicable scope of raw materials of the adsorbent and is still applicable to diesel raw materials containing sulfur and nitrogen impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Diesel dearomatization process diagram;

[0022] Figure 2 Schematic diagram of the position and switching direction of materials entering and exiting the simulated moving bed;

[0023] Figure 3 Infrared spectrum of the amino-modified adsorbent prepared in Example 1. DETAILED DESCRIPTION

[0024] The technical solutions and technical effects of the present invention are further described below with reference to the accompanying drawings and specific embodiments.

[0025] The present invention provides a diesel dearomatization adsorbent. The diesel dearomatization adsorbent is in the form of spherical particles. Based on the total mass of the adsorbent, the carbon content is 5 to 15% by mass, preferably 6 to 12%, the nitrogen content is 1 to 10% by mass, preferably 2 to 6%, the C / N ratio is not less than 2.0, preferably 2.0 to 2.5, and the silicon dioxide content is 80 to 95% by mass, preferably 85 to 92% by mass.

[0026] In the infrared spectrum of the adsorbent of the present invention, the NH stretching vibration peak of the amino group is between 1300 and 1600 cm -1 The stretching vibration peak of the C-H bond is between 2800 and 3000 cm -1 .

[0027] The specific surface area of ​​the adsorbent of the present invention is 500-800m 2 / g, the micropore surface area accounts for at least 75% of the total surface area, and the pore volume is 0.1-1cm 3 / g, pore size is 1 to 10 nm.

[0028] The toluene adsorption capacity of the adsorbent of the present invention is not less than 300 mg / g, the adsorbent breakage rate is not more than 2 wt% under a pressure of 250 N, and the calcined bulk density at 200° C. is not less than 0.76 mg / mL.

[0029] The present invention provides a method for preparing a diesel dearomatization adsorbent, comprising:

[0030] S1. Using water glass and sulfuric acid as raw materials, synthesizing silica sol, drying and granulating to obtain adsorbent particles;

[0031] S2. After pre-acidification of the surface of the adsorbent particles, washing to neutrality, and drying for later use;

[0032] S3. Stirring the pre-acidified adsorbent particles with an organic amine solution to react, to obtain an amino-modified adsorbent, which is then dried and activated for later use.

[0033] In step S1, the reaction raw materials are water glass and sulfuric acid. The water glass is first preheated to a constant temperature of 55-65°C, and then sulfuric acid is slowly added to the water glass. When the pH of the mixture reaches a control value of 2-6, the mixture is stirred and aged at a constant temperature of 60-80°C for 6-24 hours to produce a silica sol. The mass concentration of Na2O in the water glass is 0.01-0.10 g / g, the mass concentration of SiO2 is 0.10-0.50 g / g, and the concentration of sulfuric acid is 0.1-1 mol / L.

[0034] The sol is washed with deionized water and then diluted with deionized water to form a slurry. The silica slurry is formed into small pellets using a spray dryer and air granulation device. 20-40 mesh silica particles are sieved and set aside. The volume ratio of the silica sol to the deionized water used for washing is 1-5.

[0035] In step S2, the adsorbent particles are pre-acidified with an inorganic acid, the adsorbent is mixed with the inorganic acid solution, stirred at 40-80°C for 6-24 hours, cooled to room temperature and filtered, and repeatedly washed with deionized water until the filtrate is neutral, then dehydrated with an organic solvent, and vacuum dried for 6-24 hours for use.

[0036] Wherein, the inorganic acid is one or more of hydrochloric acid, sulfuric acid and nitric acid, the concentration of the inorganic acid solution is 1 to 20% by mass, and the volume ratio of the adsorbent to the inorganic acid is 1 to 20.

[0037] The organic solvent for dehydration is one or more of methanol, anhydrous ethanol, acetone, and dichloromethane, and the vacuum drying temperature is 60-90°C.

[0038] In step S3, the organic amine and the organic solvent are fully stirred and mixed to obtain an organic amine solution, wherein the volume ratio of the organic amine to the organic solvent is 1:20 to 1:1. Preferably, the mixture is stirred and reacted at 60 to 90° C. for 6 to 24 hours, and then the pre-acidified adsorbent particles are poured into the organic amine solution. After stirring and reacting at 60 to 90° C. for 6 to 24 hours, the adsorbent particles are washed with a washing solvent to wash away excess organic amine and organic solvent. The modified adsorbent is filtered to obtain the modified adsorbent, which is then vacuum-dried at 60 to 180° C. and activated for standby use.

[0039] The organic amine is selected from one or more of aliphatic amines, alcoholamines, amides, and aminosilanes, preferably one or more of ethanolamine, diethanolamine, diethylenetriamine, 3-aminopropylsilane, methylenebisacrylamide, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, more preferably a mixture of ethanolamine and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and the mixing ratio of the two is 1:0.1 to 1:10.

[0040] The organic solvent is selected from alkanes, low-carbon aromatic hydrocarbons or low-carbon alcohol solvents, preferably one or more of methanol, ethanol, benzene, toluene, ethylbenzene, n-heptane, isooctane, dichloromethane, N,N-dimethylformamide and the like.

[0041] The organic solvent for washing is one or more of methanol, ethanol, and N,N-dimethylformamide.

[0042] The present invention also provides a method for dearomatizing diesel, comprising: applying the adsorbent of the present invention to a diesel adsorption separation process to separate aromatic components in the diesel, obtaining aromatic-rich components from the extract, and obtaining alkane-rich components from the raffinate.

[0043] The main devices of the diesel adsorption separation process include a raw material refining tower, an adsorption tower and a distillation tower, and the adsorption tower preferably adopts a simulated moving bed.

[0044] The simulated moving bed (SMB) consists of two feed streams: feedstock and desorbent, and two output streams: extract and raffinate. The extract is the material enriched in aromatics, while the raffinate is the remaining material after aromatics separation. Each feed stream periodically changes its position as it enters and exits the adsorption tower, achieving simulated movement of the adsorbent relative to the feed bed. After the extract and raffinate pass through the distillation tower, the desorbent is separated and recycled.

[0045] The analytical agent is selected from one or more of toluene, o-xylene, n-heptane, cyclohexane, methylcyclohexane, etc.

[0046] The present method uses a dynamic pulse test method to determine the adsorption and separation performance of an adsorbent. The pulse apparatus primarily consists of a feed system, a nitrogen system, and a heating furnace. The adsorption column, a straight stainless steel tube with an inner diameter of 8 mm and a length of 1000 mm, is placed in the automatic temperature-controlled heating furnace. The adsorption column is loaded with 45 g of adsorbent. The lower end of the adsorption column is connected to the feed system and nitrogen system, while the upper end is connected to a backup pressure valve and an effluent collector.

[0047] The raw materials used in the experiment consisted of a pulse liquid and a desorbent prepared in a specific ratio. The pulse liquid was prepared by diluting several components of diesel with n-nonane. The desorbent consisted of the desorbent and n-heptane, with n-heptane serving as the diluent. The modified adsorbent was vacuum-dried and activated before being loaded into an adsorption column. Nitrogen was first introduced to displace the oxygen within the adsorbent. The desorbent was then introduced to purge the system of gas. After purging, the backup pressure valve was adjusted to 0.8 MPa, and the electric furnace was activated to heat the system to the target temperature. Once the target temperature was reached, the desorbent was discontinued, a predetermined volume of pulse liquid was injected, and desorbent was then introduced for elution. Desorption samples were taken at 2 mL intervals at the column outlet until all components in the pulse liquid were completely desorbed.

[0048] In the adsorption separation operation, adsorption intensity and desorption rate are important indicators to measure the performance of the adsorbent. The present invention uses gas chromatography to analyze the composition of the sample, with the amount of desorbent used as the horizontal axis and the peak area of ​​each component in the effluent as the vertical axis to draw a mass fraction change curve of each component. The non-adsorbed component in the pulse liquid emerges first, and the midpoint of its half-peak width is taken as the zero point. The volume difference between the midpoint of the peak width of each adsorbed component curve and the zero point is the net retention volume ΔM of the component. R The larger the value, the stronger the adsorption capacity of the adsorbed component. The ratio of the net retention volume of the two components is the separation coefficient β of the two components. i / j The mutual replacement rate between the desorbent and the adsorbed components in the raw material can be measured by the half-peak width W of the mass fraction curve of each adsorbed component. 1 / 2 The smaller the half-peak width is, the faster the mass transfer rate is. The separation R of the sample is twice the ratio of the difference between the net retention volumes of the two components and the sum of their half-peak widths.

[0049] The method for determining the toluene adsorption amount of the adsorbent is as follows: take an adsorbent sample with a mass of M0, place it in an adsorption device, use a mixture of nitrogen and toluene at 35°C to saturate the sample with adsorption, the total pressure of the mixed gas is 0.1 MPa, and the net weight of the sample after adsorption is M1. The toluene adsorption amount of the sample (mg / g) = 1000×(M1-M0) / M0.

[0050] The mechanical strength of the adsorbent is characterized by the compression breakage rate of the pellets. The determination method is as follows: a proper amount of the adsorbent in air equilibrium is weighed and loaded into a closed bottom stainless steel barrel, a cylindrical needle cooperating with the stainless steel barrel is placed above the adsorbent, then the needle is pressurized to 250 N on the particle strength tester, the pressure is released, the adsorbent is taken out, sieved with a 0.3 mm sieve, the adsorbent not passing through the sieve is weighed, and the percentage of the reduced mass to the mass of the sample before pressurization is the compression breakage rate of the measured sample. The lower the breakage rate, the better the strength of the sample. When the compression breakage rate is less than 2%, the industrial use requirement is met.

[0051] The determination method of the bulk density of the adsorbent is as follows: the dry adsorbent is quickly weighed, the sample net weight is M, the sample is loaded into a glass measuring cylinder, the cylinder is placed on a tap density instrument and vibrated for 3 min, the volume V is read, wherein the vibration amplitude is 3 mm and the vibration frequency is 300 times / min. Then the bulk density (g / mL) of the adsorbent is M / V.

[0052] The element content in the sample is analyzed by X-ray fluorescence spectrometry (XRF).

[0053] Example 1

[0054] Silica aqueous solution is synthesized from water glass and sulfuric acid, the pH of the solution is kept at 6.0, the reaction is carried out at 60°C for 12 h, after washing with water, spray drying, air prilling, and sieving, the adsorbent with a mesh size of 20-40 is selected for acidification pretreatment, 10wt% hydrochloric acid is used, the volume ratio of the adsorbent to the hydrochloric acid is 1:10, the acidification pretreatment is carried out at 60°C for 12 h, after cooling to room temperature, the adsorbent is filtered, washed repeatedly with deionized water until the filtrate is neutral, then dehydrated with an organic solvent, and finally dried at 80°C under vacuum for 12 h for standby use.

[0055] Ethanolamine and toluene are selected and put into a stirring reactor at a volume ratio of 1:20, stirring is carried out at 90°C for 12 h, after the stirring is completed, the adsorbent after surface acidification is poured into the mixed solution of ethanolamine and toluene, stirring is carried out at 90°C for 12 h, after the reaction is completed, the adsorbent is washed with methanol to remove excess ethanolamine and toluene, etc., the adsorbent is vacuum dried at 60°C, and finally activated at 120°C for standby use. The toluene adsorption capacity of the adsorbent is shown in Table 1, the physical property data are shown in Table 2, and the pulse data results are shown in Table 3.

[0056] Example 2

[0057] The adsorbent is prepared according to the method of Example 1, except that the reaction pH of water glass and sulfuric acid is 5.0, and 3-aminopropylsilane is selected as the organic amine. The toluene adsorption capacity is shown in Table 1, the physical property data are shown in Table 2, and the pulse data results are shown in Table 3.

[0058] Example 3

[0059] The adsorbent was prepared according to the method of Example 1, except that the reaction pH of water glass and sulfuric acid was 5.0, 10 wt% nitric acid was used for acidification pretreatment of the adsorbent, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was selected as the organic amine. The toluene adsorption capacity is shown in Table 1, the physical property data are shown in Table 2, and the pulse data results are shown in Table 3.

[0060] Example 4

[0061] The adsorbent was prepared according to the method of Example 1, except that the reaction pH of water glass and sulfuric acid was 5.0, 10 wt% nitric acid was used for adsorbent acidification pretreatment, and ethanolamine and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane were selected as organic amines in a mass ratio of 1:1. The toluene adsorption capacity is shown in Table 1, the physical property data are shown in Table 2, and the pulse data results are shown in Table 3.

[0062] Example 5

[0063] The adsorbent was prepared according to the method of Example 4, except that ethanolamine and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane were used as organic amines in a mass ratio of 1:5. The toluene adsorption capacity is shown in Table 1, the physical property data are shown in Table 2, and the pulse data results are shown in Table 3.

[0064] Comparative Example 1

[0065] A silica solution was synthesized using water glass and sulfuric acid as raw materials. The solution was controlled at pH 6.0 and reacted at 60°C for 12 hours. After washing with water, it was spray-dried and air-granulated. The adsorbent with a mesh size of 20-40 was selected by sieving and vacuum-dried at 150°C for later use. The toluene adsorption capacity is shown in Table 1, and the physical properties are shown in Table 2. The pulse data results are shown in Table 3.

[0066] Example 6

[0067] The adsorbent of Example 4 was applied to the process of diesel adsorption separation and dearomatization, and the process route was as follows: Figure 1 As shown, the main equipment includes a raw material refining tower, an adsorption tower and a distillation tower, wherein the adsorption tower adopts a simulated moving bed process, such as Figure 2 The diesel raw material first enters the raw material refining tower. The raw material used is hydrogenated straight diesel from a refinery. Its composition is shown in Table 4. The diesel refining agent used is the adsorbent in Example 4. The pretreatment temperature is 60°C, the pressure is 0.8MPa, and the air velocity is 0.1h -1 The refined feedstock enters the simulated moving bed in the fourth zone and is fed with a desorbent, toluene. After adsorption separation of the diesel feedstock, an extract E rich in aromatic components and a raffinate R rich in alkane components are obtained. After the extract E and raffinate R pass through the distillation tower, the desorbent is separated and recycled.

[0068] The four-zone simulated moving bed contains 12 beds, which are divided into a desorption zone, a purification zone, an adsorption zone, and a buffer zone. The bed configuration in each zone is 3-4-3-2, i.e., 3 beds in the desorption zone, 4 beds in the purification zone, 3 beds in the adsorption zone, and 2 beds in the buffer zone. Each bed is evenly loaded with the adsorbent in Example 4. The adsorption and desorption temperature is 100°C, the feed injection temperature is 100°C, the desorbent injection temperature is 100°C, the desorbent and feed mass ratio is 2:1, and the step time is 160s. The feed mass ratio of desorbent to feed is 0.9:1, and the circulation volume to feed mass ratio is 1.4:1. After adsorption separation, the aromatic hydrocarbon content in the extract E and the raffinate R is shown in Table 5.

[0069] In Table 5, the hydrocarbon composition was determined by gas chromatography-mass spectrometry, the sulfur content was determined by energy dispersive X-ray fluorescence spectrometry, and the nitrogen content was determined by oxidative combustion and chemiluminescence.

[0070] Aromatic purity = mass of aromatics in the extract / total mass of the extract × 100%

[0071] Aromatic hydrocarbon yield = mass of aromatic hydrocarbons in the extract / mass of aromatic hydrocarbons in the feed × 100%

[0072] Example 7

[0073] A simulated moving bed experiment was conducted according to the method of Example 6, except that the raw material used was unhydrogenated diesel from a refinery, the composition of which is shown in Table 4. After adsorption separation, the aromatic hydrocarbon content in the extract E and the raffinate R is shown in Table 5, and the sulfur and nitrogen impurity contents are shown in Table 5.

[0074] Comparative Example 2

[0075] A simulated moving bed experiment was conducted according to the method of Example 7, except that the adsorbent of Comparative Example 1 was used. After adsorption separation, the aromatic hydrocarbon content in the extract E and the raffinate R is shown in Table 5, and the sulfur and nitrogen impurity contents are shown in Table 5.

[0076] Table 1 Toluene static adsorption capacity

[0077]

[0078] Table 2 Physical properties of adsorbents

[0079]

[0080] Table 3 Pulse data results

[0081]

[0082] Table 4 Diesel raw material composition

[0083] Diesel properties Hydrotreated diesel Unhydrogenated diesel Sulfur content / (mg / g) 1 9400 Nitrogen content / (mg / g) ＜0.2 30 Alkanes 48.2 48.8 Monocycloalkanes 15 16.3 Bicycloalkanes 12.8 9.8 tricycloalkanes 3.4 2.2 Total cycloalkanes 31.2 28.3 Total saturated hydrocarbons 79.4 77.1 Alkylbenzenes 7.2 9.8 Indane or tetralin 8.8 4.2 Indenes 1.4 2.1 Total monocyclic aromatic hydrocarbons 17.4 16.1 Naphthalene 0.2 0.4 Naphthalene 1.5 4.1 Acenaphthenes 0.7 0.9 Acenaphthylene 0.6 1 Total bicyclic aromatic hydrocarbons 3 6.4 tricyclic aromatic hydrocarbons 0.2 0.4 Total aromatics 20.6 22.9 colloid 0 0 gross weight 100 100

[0084] Table 5 results of simulated moving bed evaluation

[0085] Example Example 6 Example 7 Comparative Example 2 Purity of aromatics in the extracted liquid / % 97.7 94.4 94.1 Purity of aromatics in the raffinate / % 4.6 5.5 8.3 Aromatic component yield / % 79.95 76.03 63.81 Sulfur content of extracted liquid / wt% - 3.43 0.023 Extracted liquid nitrogen content / mg / L - 38.33 6.00 Sulfur content of raffinate / wt% - 0.30 0.21 Residual liquid nitrogen content / mg / L - 8.86 6.09

[0086] From the data analysis of Table 1-Table 5, after the modification of the silica adsorbent by organic amine, the static adsorption capacity of toluene is increased by about 6-10%, the anti-crushing rate is slightly increased, but still meets the requirements of industrial use. The ignition base bulk density is increased, under the condition of a certain packing volume, the packing mass is increased; or under the condition of a certain packing mass, the adsorption tower volume can be reduced. The analysis of the pulse experiment results shows that after the modification of the silica adsorbent by organic amine, the separation factor and separation degree of different types of aromatic hydrocarbons and alkanes are greatly improved. In industrial applications, the separation degree of the adsorbent is preferred, and under the premise of high separation degree, the separation factor is selected. Considering the separation degree of MX, tetralin and methylnaphthalene relative to methylcyclohexane, the performance of the adsorbent in Example 5 is the best, but the separation factor of Example 4 is greater than that of Example 5, therefore, the adsorbent in Example 4 is preferentially selected for the simulated moving bed experiment. When treating hydrotreated diesel, the purity and yield of aromatic components are both high, and when treating poor untreated diesel, the selectivity of the adsorbent to aromatic components is still high, and the adsorbent also has selectivity to sulfur and nitrogen impurities. Sulfur and nitrogen substances can be adsorbed and desorbed on the adsorbent, therefore, after the modification by amino, the application range of the adsorbent to diesel raw materials is widened, and the harshness of the diesel raw materials is reduced.

Claims

1. A method for preparing a diesel dearomatization adsorbent, comprising: S1. Using water glass and sulfuric acid as raw materials, synthesizing silica sol, drying and granulating to obtain adsorbent particles; S2. After pre-acidification of the surface of the adsorbent particles, washing to neutrality, and drying for later use; S3. Stirring the pre-acidified adsorbent particles with an organic amine solution to react to obtain an amino-modified adsorbent, which is then dried and activated for standby use, wherein the organic amine is selected from a mixture of ethanolamine and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and the mass mixing ratio of the two is 1:0.1 to 1:10, and the organic amine solution is obtained by mixing the organic amine with an organic solvent.

2. The preparation method according to claim 1, wherein In step S1, in the water glass, the mass concentration of Na2O is 0.01~0.10g / g, the mass concentration of SiO2 is 0.10~0.50g / g; and the concentration of sulfuric acid is 0.1~1mol / L.

3. The preparation method according to claim 1, wherein In step S2, the adsorbent is mixed with the inorganic acid solution and stirred at 40-80°C for 6-24 hours.

4. The preparation method according to claim 3, wherein The concentration of the inorganic acid solution is 1-20% by mass, and the volume ratio of the adsorbent to the inorganic acid is 1-20.

5. The preparation method according to claim 1, wherein The organic amine is selected from a mixture of ethanolamine and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and the mass mixing ratio of the two is 1:1 to 1:

5.

6. The preparation method according to claim 1, wherein The organic solvent is selected from alkanes, low-carbon aromatic hydrocarbons or low-carbon alcohol solvents.

7. The preparation method according to claim 1, wherein The organic solvent is selected from one or more of methanol, ethanol, benzene, toluene, ethylbenzene, n-heptane, isooctane, dichloromethane, and N,N-dimethylformamide.

8. The preparation method according to claim 1, wherein Mix the organic amine and the organic solvent in a volume ratio of 1:20 to 1:1, and stir the mixture at 60 to 90°C for 6 to 24 hours.

9. The preparation method according to claim 1, wherein Pour the pre-acidified adsorbent particles into the organic amine solution, stir and react at 60-90°C for 6-24 hours, wash and filter to obtain the amino-modified adsorbent, vacuum dry at 60-180°C, and activate for use.

10. The adsorbent obtained by the method according to any one of claims 1 to 9.

11. The adsorbent according to claim 10, wherein the carbon content is 5-15% by mass, the nitrogen content is 1-10% by mass, the C / N ratio is not less than 2.0, and the silicon dioxide content is 80-95% by mass, based on the total mass of the adsorbent.

12. The adsorbent according to claim 10, wherein Based on the total mass of the adsorbent, the carbon content is 6-12%, the nitrogen content is 2-6%, the C / N ratio is 2.0-2.5, and the silica content is 85-92% by mass.

13. The adsorbent according to claim 10, wherein The specific surface area of ​​the adsorbent is 500~800m 2 / g, the micropore surface area accounts for at least 75% of the total surface area, and the pore volume is 0.1~1cm 3 / g, pore size is 1~10nm.

14. A method for dearomatizing diesel, comprising: The adsorbent according to any one of claims 10 to 13 is applied to a diesel adsorption separation process to separate aromatic components from diesel, thereby obtaining an aromatic-rich component from the extracted liquid and an alkane-rich component from the raffinate.

15. The method according to claim 14, wherein The main equipment of diesel adsorption separation process includes raw material refining tower, adsorption tower and distillation tower.

16. The method according to claim 15, wherein The adsorption tower adopts a simulated moving bed.

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