An aromatic hydrocarbon adsorbent for simulating a moving bed, its preparation method, and its application.

Abstract

This application provides an aromatic hydrocarbon adsorbent for simulating a moving bed and its preparation method, relating to the field of aromatic hydrocarbon adsorbent technology. The preparation method includes: modifying molecular sieve powder with a modifier to obtain modified powder; preparing seed pellets using the modified powder; growing the seed pellets and the modified powder to form small particles with a particle size of 0.5–1.5 mm; and drying and calcining the small particles to obtain the aromatic hydrocarbon adsorbent. The aromatic hydrocarbon adsorbent is prepared by the aforementioned method. The aromatic hydrocarbon adsorbent prepared in this application exhibits high selective adsorption capacity for aromatic hydrocarbons and good stability.

Description

Technical Field

[0001] This application relates to the field of aromatic adsorbent technology, and in particular to an aromatic adsorbent for simulating a moving bed, its preparation method, and its application. Background Technology

[0002] Under the dual pressures of slowing economic growth and the rapid development of alternative energy sources in my country, the growth rate of refined oil demand has slowed, with diesel consumption essentially reaching its peak. Gasoline consumption is projected to peak around 2025. Unlike the refined oil market, demand for basic chemicals such as olefins and aromatics is strong, but domestic production capacity is insufficient, necessitating substantial imports. If the components of diesel can be separated to obtain high-purity straight-chain alkanes, cycloalkanes, isoalkanes, and aromatics, these high-purity aromatics can serve as high-quality aromatic solvents or high-quality BTX (benzene, toluene, xylene) production-enhancing feedstocks. This would not only achieve classified management of gasoline and diesel components, providing raw materials for efficient conversion and accurate processing of gasoline and diesel, but also reduce the diesel-to-gasoline ratio in refineries, improving the economic and social benefits for enterprises.

[0003] Industrially, oil separation technologies for mixed aromatic components mainly include precision distillation, membrane separation, and adsorption separation. Precision distillation utilizes the differences in boiling points of the components to achieve separation and purification, but it results in a narrow separation range and is complex and difficult to operate. Membrane separation technology mainly utilizes the differences in diffusion coefficients of different components as they pass through the membrane to separate mixed components. Although it has advantages such as low energy consumption and simple process, the fabrication of separation membranes is complex and costly, and it is difficult to achieve a balance between high throughput and high selectivity, which limits its industrial application. The main methods of adsorption separation technology are fixed-bed and simulated moving-bed adsorption separation. Compared with precision distillation and membrane separation, adsorption separation technology has advantages such as higher product recovery and purity, lower energy consumption, longer adsorbent life, and stable operation.

[0004] However, most current adsorption separation technologies suffer from problems such as low purity of aromatic components and low yield of target products, which means that aromatic components must undergo further purification processes before they can be used, increasing processing costs. Summary of the Invention

[0005] To address the issues of low purity and low yield of target products in current aromatic adsorption and separation technologies, this application provides an aromatic adsorbent for simulated moving beds, its preparation method, and its application.

[0006] In a first aspect, this application provides a method for preparing an aromatic adsorbent for simulating a moving bed, employing the following technical solution:

[0007] A method for preparing an aromatic adsorbent for simulating a moving bed includes the following steps:

[0008] Step S1: Modify the molecular sieve powder using a modifier to obtain modified powder;

[0009] Step S2: Prepare seed bulbs using modified raw powder;

[0010] Step S3: Using the seed pellets and the modified raw powder, the pellets are grown into small granules with a particle size of 0.5 to 1.5 mm.

[0011] Step S4: Dry and calcine the granules to obtain the aromatic adsorbent.

[0012] This application modifies the molecular sieve powder to ensure the adsorbent possesses excellent adsorption performance and stability. The modification step improves the selective adsorption capacity for aromatics by adjusting the surface properties and structure of the molecular sieve. The seeding and pelleting steps ensure the uniformity of the adsorbent particles and a suitable particle size range, which helps to improve adsorption efficiency and reduce bed pressure drop. The drying and calcination steps further remove moisture and organic matter from the adsorbent, stabilize its structure, and improve its thermal and chemical stability.

[0013] Optionally, the modified raw powder includes molecular sieve raw powder, pore expander and binder, wherein the weight ratio of molecular sieve raw powder to pore expander is 88-92:8-12, and the weight of binder is 4%-6% of the sum of the weights of molecular sieve raw powder and pore expander.

[0014] Furthermore, the modified raw powder includes molecular sieve raw powder, pore expander and binder, wherein the dry basis weight ratio of the molecular sieve raw powder and the pore expander after high-temperature calcination is 88-92:8-12, and the weight of the binder is 4%-6% of the sum of the dry basis weights of the molecular sieve raw powder and the pore expander after high-temperature calcination.

[0015] This application further defines the raw material composition of the modified powder. By adding pore expanders and binders and mixing them with molecular sieve powder, the structure and performance of the adsorbent can be optimized. Pore expanders help increase porosity and improve pore structure, thereby increasing adsorption capacity and diffusion rate. Binders help with particle formation and stability, preventing particle breakage and agglomeration during preparation and use.

[0016] Optionally, the specific operation of step S1 is as follows:

[0017] The molecular sieve powder, the pore expander, the binder and water are mixed to form a slurry with a solid content of 30% to 50%, and the pH value of the slurry is adjusted to 3 to 5 and stirred evenly.

[0018] The slurry is heated to 90-100°C, a modifier solution is added, and the temperature is maintained at this level for 2-4 hours to obtain the modified material.

[0019] The modified material is dehydrated and dried, and the dried material is pulverized to below 200 mesh to obtain the modified raw powder.

[0020] This application forms a slurry by mixing molecular sieve powder, pore expander, binder and water, and adjusts the pH value to ensure uniform distribution and interaction among the components. After heating and adding a modifier solution, the modifier can fully combine with the active sites on the surface of the molecular sieve powder to form new chemical bonds or change the chemical properties of the surface, thereby improving its adsorption capacity for aromatics.

[0021] This application, by adjusting the pH value of the slurry before modification, helps to form stronger chemical bonds between the modifier molecules and the active sites on the surface of the molecular sieve powder. The formation of these chemical bonds enhances the binding force between molecular sieve particles, thereby improving the overall strength of the product and reducing wear on the molecular sieve during use.

[0022] Optionally, the molecular sieve raw powder has a silicon-to-aluminum ratio of 2.2-6.0 and a static saturated water absorption of more than 32% under the conditions of 25°C and 75% humidity.

[0023] The binder is alumina or kaolin;

[0024] The pore-expanding agent is polyvinyl alcohol, guar gum powder, or starch.

[0025] This application helps ensure the adsorption capacity and stability of the molecular sieve powder by limiting its silica-to-alumina ratio and static saturated water absorption. Furthermore, the selection of binders and pore-expanding agents can optimize the structure and performance of the adsorbent.

[0026] Optionally, the modifier solution is an aqueous solution of calcium salt, magnesium salt or barium salt, and the mass concentration of the modifier solvent is 10% to 20%.

[0027] The amount of the modifier solution added is 1.875-2 times the weight of the molecular sieve raw powder.

[0028] This application utilizes a modifier to perform ion replacement modification on the molecular sieve powder, so that the sodium ions in the molecular sieve powder are replaced by divalent metal ions (calcium ions, magnesium ions, or barium ions) of the modifier. Since the valence state of the substituted ions is higher than that of sodium ions, their interaction with oxygen atoms in the molecular sieve framework is stronger, thereby enhancing the structural stability of the molecular sieve. This helps the molecular sieve maintain its shape and pore structure during adsorption and prevents structural collapse caused by pressure or temperature changes during adsorption.

[0029] Furthermore, the charge distribution of the molecular sieve changes after sodium ions are replaced by divalent ions. The substituted ions carry more positive charge, increasing the charge density on the molecular sieve surface and enhancing polarity, which facilitates the interaction between the molecular sieve and aromatic molecules. Aromatic molecules are typically polar, thus they are more easily adsorbed by the molecular sieve with enhanced polarity. This increased polarity also helps to improve the adsorption rate of aromatics by the molecular sieve. Aromatic molecules are more easily attracted to the surface of the molecular sieve and enter its pores for adsorption more quickly.

[0030] Optionally, the specific operation of step S2 is as follows: the modified raw powder is put into the sugar coating pot, the pot is rotated, and water is sprayed into the sugar coating pot at the same time, so that the modified raw powder gradually forms into round particles under the conditions of continuous rotation and water spraying. Then, the rotation is stopped, the particle material in the pot is taken out, and particles of 0.2-0.5mm are screened out as seed balls.

[0031] This application utilizes the rotation and water spraying of a sugar-coating pan to gradually shape the modified raw powder into spherical particles. By controlling the amount of water sprayed and the rotation speed, uniform and regular seed pellets can be prepared. The particle size and shape of the seed pellets directly affect the final particle size distribution of the adsorbent and the bed pressure drop.

[0032] Optionally, the specific operation of step S3 is as follows: put the seed balls back into the sugar coating pot, rotate the pot, and continuously spray water and add the modified raw powder into the sugar coating pot to make the seed ball particles gradually grow. When the particle size reaches 1.5mm, stop the growth of the balls, take out the particles in the pot, and sieve out the particles with a size of 0.5 to 1.5mm.

[0033] This application utilizes continuous water spraying and the addition of modified raw powder to gradually grow the seed pellets to the desired particle size range. This step ensures the uniformity and suitable particle size range of the adsorbent particles, which helps improve adsorption efficiency and reduce bed pressure drop. Simultaneously, by precisely controlling the amount of water sprayed and the amount of modified raw powder added, precise control of the particle size can be achieved, thereby obtaining adsorbent particles that meet the requirements.

[0034] Optionally, the drying temperature in step S4 is 120-150℃, and the drying time is 2-4 hours.

[0035] Optionally, the calcination process in step S4 is carried out in a stepped heating manner, wherein the granules are kept at constant temperatures of 180-200℃, 280-300℃, 380-400℃, and 550-600℃ for 1-2 hours each.

[0036] This application utilizes a calcination process to remove moisture and organic matter from the adsorbent. The stepped heating method helps avoid structural damage and performance degradation caused by rapid temperature increases, further improving the adsorption performance and stability of the adsorbent.

[0037] Secondly, this application provides an aromatic hydrocarbon adsorbent prepared by the above-described preparation method.

[0038] The aromatic hydrocarbon adsorbent prepared in this application has high selective adsorption capacity for aromatic hydrocarbons and good stability.

[0039] Thirdly, this application provides an application of an aromatic hydrocarbon adsorbent, which is applied to a simulated moving bed for adsorbing and separating aromatic hydrocarbons in mixed oil products.

[0040] When the above-mentioned aromatic adsorbent is used for the adsorption and separation of aromatics, it can adsorb various aromatics in the mixed oil products, thereby separating the aromatics from the mixed oil products. The aromatic component products obtained have an aromatic purity of over 99%, which can be directly applied to downstream production.

[0041] In summary, this application includes at least one of the following beneficial effects:

[0042] 1. This application modifies the molecular sieve powder to ensure the adsorbent possesses excellent adsorption performance and stability. The modification step improves the selective adsorption capacity for aromatics by adjusting the surface properties and structure of the molecular sieve. The seeding and pelleting steps ensure the uniformity of the adsorbent particles and a suitable particle size range, which helps to improve adsorption efficiency and reduce bed pressure drop. The drying and calcination steps further remove moisture and organic matter from the adsorbent, stabilize its structure, and improve its thermal and chemical stability.

[0043] 2. The aromatic adsorbent prepared in this application has high selective adsorption capacity for aromatics and good stability.

[0044] 3. When the above-mentioned aromatic adsorbent is used for the adsorption and separation of aromatics, it can adsorb various aromatics in the mixed oil products, thereby separating the aromatics from the mixed oil products. The aromatic component products obtained have an aromatic purity of more than 99%, which can be directly applied to downstream production. Detailed Implementation

[0045] Example 1

[0046] Example 1 provides an aromatic hydrocarbon adsorbent, as detailed below:

[0047] (1) Raw material preparation. 13X molecular sieve powder was selected as the molecular sieve raw material, with a silicon-to-aluminum ratio of 2.4, a static saturated water absorption of 33 wt% under conditions of 25℃ and 75% humidity, and a loss on ignition of 25% at 600℃. Alumina powder was selected as the binder, with a specific surface area of ​​250 g / m². 2The pore volume is 0.5 ml / g, and the loss on ignition at 600℃ is 35%. 100% pure polyvinyl alcohol was selected as the pore-expanding agent. The amounts of the three raw materials used were 100 kg of 13X molecular sieve powder, 15.8 kg of alumina powder, and 3.42 kg of polyvinyl alcohol. After ignition at 600℃, the dry weights of the first two powders were 75 kg and 10.27 kg, respectively. Therefore, the dry weight ratio of 13X molecular sieve powder, alumina powder, and polyvinyl alcohol was 88:12:4.

[0048] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: polyvinyl alcohol, alumina powder, and 13X molecular sieve powder. After adding all three materials, adjust the pH of the slurry to 4 using nitric acid and stir at 100 rpm for 30 minutes. Then, heat the material in the reactor to 95°C, add 150 kg of the prepared 10 wt% calcium chloride solution, and maintain the temperature at 95°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake-shaped material after dehydration into a tray and put it into an oven. Heat it to 150°C and maintain the temperature for 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0049] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0050] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0051] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 140℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 580℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0052] Example 2

[0053] Example 2 provides an aromatic hydrocarbon adsorbent, as detailed below:

[0054] (1) Raw material preparation. 13X molecular sieve powder was selected as the molecular sieve raw material, with a silicon-to-aluminum ratio of 2.3, a static saturated water absorption of 33 wt% under conditions of 25℃ and 75% humidity, and a loss on ignition of 22% at 600℃. Alumina powder was selected as the binder, with a specific surface area of ​​260 g / m². 2 The pore volume is 0.58 ml / g, and the loss on ignition at 600℃ is 35%. 100% pure polyvinyl alcohol was selected as the pore-expanding agent. The amounts of the three raw materials used were 100 kg of 13X molecular sieve powder, 13.3 kg of alumina powder, and 4.32 kg of polyvinyl alcohol. The dry weights of the first two powders after ignition at 600℃ were 78 kg and 8.645 kg, respectively. Therefore, the dry weight ratio of 13X molecular sieve powder, alumina powder, and polyvinyl alcohol was 90:10:5.

[0055] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: polyvinyl alcohol, alumina powder, and 13X molecular sieve powder. After adding all three materials, adjust the pH of the slurry to 5 using nitric acid and stir at 100 rpm for 30 minutes. Then, heat the material in the reactor to 95°C, add 150 kg of the prepared 15 wt% magnesium chloride solution, and maintain the temperature at 95°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake-shaped material after dehydration into a tray and put it into an oven. Heat it to 150°C and maintain the temperature for 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0056] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0057] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0058] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 140℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 590℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0059] Example 3

[0060] Example 3 provides an aromatic hydrocarbon adsorbent, as detailed below:

[0061] (1) Raw material preparation. 13X molecular sieve powder was selected as the molecular sieve raw material, with a silicon-to-alumina ratio of 2.5. Its static saturated water absorption at 25℃ and 75% humidity was 33wt%, and its loss on ignition at 600℃ was 23%. Kaolin powder was selected as the binder, with a loss on ignition at 600℃ of 39%. 100% pure polyvinyl alcohol was selected as the pore-expanding agent. The amounts of the three raw materials were 100 kg of 13X molecular sieve powder, 11 kg of kaolin powder, and 4.19 kg of polyvinyl alcohol. The dry basis weights of the first two powders after ignition at 600℃ were 77 kg and 6.71 kg, respectively. Therefore, the dry basis weight ratio of 13X molecular sieve powder, alumina powder, and polyvinyl alcohol was 92:8:5.

[0062] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: polyvinyl alcohol, kaolin powder, and 13X molecular sieve powder. After adding the three materials, adjust the pH of the slurry to 3 using nitric acid and stir at 100 rpm for 30 minutes. Then, heat the material in the reactor to 95°C, add 150 kg of the prepared 15 wt% magnesium chloride solution, and keep the temperature at 95°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake-shaped material after dehydration into a tray and put it into an oven. Heat it to 150°C and keep it at 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0063] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0064] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0065] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 140℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 600℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0066] Example 4

[0067] Example 4 provides an aromatic hydrocarbon adsorbent, as detailed below:

[0068] (1) Raw material preparation. 13X molecular sieve powder was selected as the molecular sieve raw material, with a silicon-to-alumina ratio of 2.5. Its static saturated water absorption under conditions of 25℃ and 75% humidity was 34wt%, and its loss on ignition at 600℃ was 23%. Kaolin powder was selected as the binder, with a loss on ignition at 600℃ of 39%. 100% pure polyvinyl alcohol was selected as the pore-expanding agent. The amounts of the three raw materials were 100 kg of 13X molecular sieve powder, 12.5 kg of kaolin powder, and 3.38 kg of polyvinyl alcohol. The dry weights of the first two powders after ignition at 600℃ were 77 kg and 7.625 kg, respectively. Therefore, the dry weight ratio of 13X molecular sieve powder, alumina powder, and polyvinyl alcohol was 91:9:4.

[0069] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: polyvinyl alcohol, kaolin powder, and 13X molecular sieve powder. After adding the three materials, adjust the pH of the slurry to 4 using nitric acid and stir at 110 rpm for 30 minutes. Then, heat the material in the reactor to 94°C, add 150 kg of the prepared 15 wt% barium chloride solution, and keep the temperature at 94°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake-shaped material after dehydration into a tray and put it into an oven. Heat it to 140°C and keep it at the temperature for 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0070] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0071] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0072] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 150℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 600℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0073] Example 5

[0074] Example 5 provides an aromatic hydrocarbon adsorbent, as detailed below:

[0075] (1) Raw material preparation. 13X molecular sieve powder was selected as the molecular sieve raw material, with a silica-alumina ratio of 2.3. Its static saturated water absorption at 25℃ and 75% humidity was 34wt%, and its loss on ignition at 600℃ was 23%. Kaolin powder was selected as the binder, with a loss on ignition at 600℃ of 39%. Starch was selected as the pore-expanding agent. The amounts of the three raw materials were 100 kg of 13X molecular sieve powder, 12.5 kg of kaolin powder, and 5.07 kg of starch (weight after high-temperature ignition). The dry basis weights of the first two powders after ignition at 600℃ were 77 kg and 7.625 kg, respectively. Therefore, the dry basis weight ratio of 13X molecular sieve powder, alumina powder, and starch was 91:9:6.

[0076] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: starch, kaolin powder, and 13X molecular sieve powder. After adding all three materials, adjust the pH of the slurry to 4 using nitric acid and stir at 110 rpm for 30 minutes. Then, heat the material in the reactor to 93°C, add 150 kg of the prepared 13wt% calcium chloride solution, and keep the temperature at 93°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake-shaped material after dehydration into a tray and put it into an oven. Heat the oven to 130°C and keep the temperature at 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0077] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0078] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0079] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 150℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 590℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0080] Example 6

[0081] Example 6 provides an aromatic hydrocarbon adsorbent, as detailed below:

[0082] 1) Raw material preparation. NaY molecular sieve powder was selected as the molecular sieve raw material, with a silica-alumina ratio of 5.5. Its static saturated water absorption at 25℃ and 75% humidity was 32wt%, and its loss on ignition at 600℃ was 20%. Kaolin powder was selected as the binder, with a loss on ignition at 600℃ of 39%. Guaranteed sesame powder was selected as the pore-expanding agent. The amounts of the three raw materials were 100 kg of NaY molecular sieve powder, 17.9 kg of kaolin powder, and 3.63 kg of guaranteed sesame powder (weight after high-temperature ignition). The dry basis weights of the first two powders after ignition at 600℃ were 80 kg and 10.919 kg, respectively. Therefore, the dry basis weight ratio of 13X molecular sieve powder, alumina powder, and guaranteed sesame powder was 88:12:4.

[0083] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: guar gum powder, kaolin powder, and NaY molecular sieve raw powder. After adding all three materials, adjust the pH of the slurry to 4 using nitric acid and stir at 110 rpm for 30 minutes. Then, heat the material in the reactor to 95°C, add 150 kg of the prepared 13wt% calcium chloride solution, and keep the temperature at 95°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake-shaped material after dehydration into a tray and put it into an oven. Heat the temperature to 130°C and keep it at 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0084] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0085] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0086] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 130℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 580℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0087] Example 7

[0088] Example 7 provides an aromatic hydrocarbon adsorbent, as detailed below:

[0089] 1) Raw material preparation. NaY molecular sieve powder was selected as the molecular sieve raw material, with a silica-alumina ratio of 5.2, a static saturated water absorption of 33wt% under conditions of 25℃ and 75% humidity, and a loss on ignition of 20% at 600℃. Kaolin powder was selected as the binder, with a loss on ignition of 39% at 600℃. 100% pure polyvinyl alcohol was selected as the pore-expanding agent. The amounts of the three raw materials were 100 kg of NaY molecular sieve powder, 11.4 kg of kaolin powder, and 3.48 kg of polyvinyl alcohol. The dry basis weights of the first two powders after ignition at 600℃ were 80 kg and 6.954 kg, respectively. Therefore, the dry basis weight ratio of 13X molecular sieve powder, alumina powder, and polyvinyl alcohol was 92:8:4.

[0090] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: polyvinyl alcohol, kaolin powder, and NaY molecular sieve powder. After adding the three materials, adjust the pH of the slurry to 4 using nitric acid and stir at 100 rpm for 30 minutes. Then, heat the material in the reactor to 92°C, add 150 kg of the prepared 18 wt% calcium chloride solution, and keep the temperature at 92°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake-shaped material after dehydration into a tray and put it into an oven. Heat it to 130°C and keep it at the temperature for 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0091] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0092] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0093] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 130℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 560℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0094] Comparative Example 1

[0095] Comparative Example 1 is basically the same as Example 1, except that it uses unmodified molecular sieve powder for preparation. The specific steps of Comparative Example 1 are as follows:

[0096] (1) Raw material preparation. 13X molecular sieve powder was selected as the molecular sieve raw material, with a silicon-to-aluminum ratio of 2.4, a static saturated water absorption of 33 wt% under conditions of 25℃ and 75% humidity, and a loss on ignition of 25% at 600℃. Alumina powder was selected as the binder, with a specific surface area of ​​250 g / m². 2 The pore volume is 0.5 ml / g, and the loss on ignition at 600℃ is 35%. 100% pure polyvinyl alcohol was selected as the pore-expanding agent. The amounts of the three raw materials used were 100 kg of 13X molecular sieve powder, 15.8 kg of alumina powder, and 3.42 kg of polyvinyl alcohol. After ignition at 600℃, the dry weights of the first two powders were 75 kg and 10.27 kg, respectively. Therefore, the dry weight ratio of 13X molecular sieve powder, alumina powder, and polyvinyl alcohol was 88:12:4.

[0097] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the three raw materials in the following order: polyvinyl alcohol, alumina powder, and 13X molecular sieve raw powder. After adding all three materials, stir at 100 rpm for 30 minutes to obtain a mixture. Put the mixture into a centrifuge to dehydrate, and put the cake material after dehydration into a tray and put it into an oven. After heating to 150℃, keep the temperature constant for 4 hours, take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into a bag to obtain the raw powder.

[0098] (3) Weigh 20kg of raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0099] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle diameter reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to obtain particles of 0.5 to 1.5 mm.

[0100] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 140℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 580℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0101] Comparative Example 2

[0102] Comparative Example 2 is basically the same as Example 1, except that no pore expander was added during the modification of the molecular sieve powder. The specific steps of Comparative Example 2 are as follows:

[0103] (1) Raw material preparation. 13X molecular sieve powder was selected as the molecular sieve raw material, with a silicon-to-aluminum ratio of 2.4, a static saturated water absorption of 33 wt% under conditions of 25℃ and 75% humidity, and a loss on ignition of 25% at 600℃. Alumina powder was selected as the binder, with a specific surface area of ​​250 g / m². 2 The pore volume is 0.5 ml / g, and the loss on ignition at 600℃ is 35%. The amounts of the two raw materials used are 100 kg of 13X molecular sieve powder and 15.8 kg of alumina powder. After ignition at 600℃, the dry weights of the two powders are 75 kg and 10.27 kg, respectively. Therefore, the dry weight ratio of 13X molecular sieve powder to alumina powder is 88:12.

[0104] (2) Add 200 liters of deionized water to the reactor, start stirring, and add the two raw materials in the order of alumina powder and 13X molecular sieve powder. After both materials are added, adjust the pH of the slurry to 4 with nitric acid and stir at 100 rpm for 30 minutes. Then heat the material in the reactor to 95°C, add 150 kg of the prepared 10wt% calcium chloride solution, and keep the temperature at 95°C for 4 hours to obtain the modified material. Put the modified material into a centrifuge to dehydrate, and put the cake material after dehydration into a tray and put it into an oven. Heat it to 150°C and keep it at 4 hours. Take out the material and send it to a pulverizer for pulverization. The particle size is greater than 200 mesh. Pack it into bags to obtain the modified raw powder.

[0105] (3) Weigh 20kg of modified raw powder and pour it into a sugar coating pot with a diameter of 1 meter. Rotate the pot and keep the rotation speed at 20 revolutions per minute. Continuously spray deionized water into the pot. Under the conditions of continuous rotation and water spraying, the powder gradually forms round particles. After rotating for 30 minutes, stop rotating, take out the particle material in the pot, sieve it, and sieve out particles of 0.2-0.5mm as seed balls.

[0106] (4) Place the seed balls back into the sugar coating pot with a diameter of 1.2 meters to grow the balls. Start the sugar coating pot and keep the rotation speed at 30 rpm. At the same time, continuously spray water and the modified raw powder obtained above into the sugar coating pot, control the humidity of the material, and ensure that the particles roll smoothly in the pot. After repeatedly adding water and powder, the seed ball particles gradually grow. When the particle size reaches 1.5 mm, stop growing the balls, take out the particles in the pot, and sieve to select 0.5-1.5 mm particles.

[0107] (5) The above-mentioned 0.5-1.5mm granules are placed in a drying oven at 140℃. After 4 hours, they are placed in a converter for roasting. The temperature of each point in the converter is controlled at 200℃, 300℃, 400℃ and 580℃, and the dwell time at each point is 1 hour. After roasting, the material is discharged and sealed and packaged as finished product while hot for later use.

[0108] Performance testing

[0109] An oil product rich in mixed aromatics was prepared as an adsorption feedstock, the main components of which were: n-alkanes, isoalkanes, cycloalkanes and mixed aromatics (benzene, toluene, m-xylene), with an aromatic content of 25.3%.

[0110] The adsorbent was loaded into a simulated moving bed, and the aromatic hydrocarbon adsorption and separation was performed using a countercurrent simulated moving bed adsorption and separation process. The adsorption bed consisted of 12 layers, the adsorption and separation temperature was 120℃, the pressure was 1MPa, and the desorbent was 98.8% pure m-diethylbenzene. Two streams were collected from the simulated moving bed: one stream was the extract rich in aromatic components, and the other stream was the raffinate rich in non-aromatic components. Samples of the extract were taken for analysis. The analysis included aromatic hydrocarbon purity, aromatic hydrocarbon recovery rate, aromatic hydrocarbon adsorption capacity, adsorbent bulk density, and wear. The adsorbent bulk density was obtained according to GB / T6286-2021, the method for determining the bulk density of molecular sieves; the wear was obtained according to GB / T10505.2-1989, the method for determining the wear rate of 3A molecular sieves. Aromatic hydrocarbon purity, aromatic hydrocarbon recovery rate, and aromatic hydrocarbon adsorption capacity were calculated using the following methods, and the specific results are shown in Table 1.

[0111] Aromatic purity = Mass of aromatics in extract / Total mass of extract × 100%;

[0112] Aromatic hydrocarbon recovery rate = Mass of aromatic hydrocarbons in the extract / Total mass of aromatic hydrocarbons in the feed feed × 100%;

[0113] Aromatic hydrocarbon adsorption capacity = weight of aromatic hydrocarbons in adsorbent / weight of adsorbent × 100%.

[0114] Table 1. Analysis results of each embodiment and comparative example.

[0115]

[0116]

[0117] As can be seen from the results in Table 1, the aromatic adsorbents prepared in Examples 1-7 have a high selectivity for aromatics in mixed oil products. Therefore, they can extract almost all the aromatics in the mixed oil products into the extract, and the extract contains more than 99% aromatics, which can be used directly without further processing. Moreover, the aromatic adsorbents obtained in Examples 1-7 also have a high adsorption capacity and low wear.

[0118] Compared with Comparative Example 1, the aromatic adsorbent obtained in Example 1 has higher aromatic selectivity and higher aromatic adsorption capacity due to the modification with calcium chloride; compared with Comparative Example 2, the aromatic adsorbent obtained in Example 1 has higher aromatic adsorption selectivity and adsorption capacity due to the addition of a pore expander during the modification process.

[0119] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing an aromatic adsorbent for simulating a moving bed, characterized in that, Includes the following steps: Step S1: Modify the molecular sieve powder using a modifier to obtain modified powder, wherein the modified powder includes molecular sieve powder, pore expander and binder; Step S2: Prepare seed bulbs using modified raw powder; Step S3: Using the seed pellets and the modified raw powder, the pellets are grown into small granules with a particle size of 0.5 to 1.5 mm. Step S4: Dry and calcine the granules to obtain the aromatic adsorbent; The specific operation of step S1 is as follows: The molecular sieve powder, the pore expander, the binder and water are mixed to form a slurry with a solid content of 30% to 50%, and the pH value of the slurry is adjusted to 3 to 5 and stirred evenly. The slurry is heated to 90-100°C, a modifier solution is added, and the temperature is maintained at this level for 2-4 hours to obtain the modified material. The modified material is dehydrated and dried, and the dried material is pulverized to below 200 mesh to obtain the modified raw powder. The modifier solution is an aqueous solution of calcium salt, magnesium salt, or barium salt.

2. The method for preparing the aromatic hydrocarbon adsorbent according to claim 1, characterized in that, The weight ratio of the molecular sieve raw powder to the pore-expanding agent is 88-92:8-12, and the weight of the binder is 4%-6% of the sum of the weights of the molecular sieve raw powder and the pore-expanding agent.

3. The method for preparing the aromatic hydrocarbon adsorbent according to claim 1, characterized in that, The molecular sieve raw powder has a silicon-to-aluminum ratio of 2.2-6.0 and a static saturated water absorption of more than 32% under conditions of 25°C and 75% humidity. The binder is alumina or kaolin; The pore-expanding agent is polyvinyl alcohol, guar gum powder, or starch.

4. The method for preparing the aromatic hydrocarbon adsorbent according to claim 1, characterized in that, The mass concentration of the modifier solvent is 10%~20%; The amount of the modifier solution added is 1.875-2 times the weight of the molecular sieve raw powder.

5. The method for preparing the aromatic hydrocarbon adsorbent according to claim 1, characterized in that, The specific operation of step S2 is as follows: the modified raw powder is put into the sugar coating pot, the pot is rotated, and water is sprayed into the sugar coating pot at the same time, so that the modified raw powder gradually forms into round particles under the conditions of continuous rotation and water spraying. Then the rotation is stopped, the particle material in the pot is taken out, and particles of 0.2-0.5mm are screened out as seed balls.

6. The method for preparing the aromatic hydrocarbon adsorbent according to claim 1, characterized in that, The specific operation of step S3 is as follows: put the seed balls back into the sugar coating pot, rotate the pot, and continuously spray water and the modified raw powder into the sugar coating pot to make the seed ball particles gradually grow. When the particle size reaches 1.5mm, stop the growth of the balls, take out the particles in the pot, and sieve out the particles with a size of 0.5~1.5mm.

7. The method for preparing the aromatic hydrocarbon adsorbent according to claim 1, characterized in that, The calcination process in step S4 adopts a stepped heating method, in which the granules are kept at constant temperatures of 180-200℃, 280-300℃, 380-400℃, and 550-600℃ for 1-2 hours each.

8. The aromatic adsorbent prepared by any one of claims 1-7.

9. The application of the aromatic hydrocarbon adsorbent according to claim 8, characterized in that, The aromatic adsorbent is applied to a simulated moving bed for the adsorption and separation of aromatics in mixed oil products.

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