5a molecular sieve adsorbent and method of making and using same

Abstract

The present application relates to the technical field of chemical adsorption separation, and discloses a 5A molecular sieve adsorbent and a preparation method and application thereof.The preparation method comprises the following steps: (1) performing ball forming on a powder containing 4A molecular sieve and a composite binder to obtain beads, and drying and calcining the beads to obtain matrix beads; (2) pre-wetting the matrix beads, and then performing calcium exchange to obtain 5A molecular sieve beads; (3) washing the 5A molecular sieve beads with water, drying, and then calcining to obtain a 5A molecular sieve adsorbent; wherein the composite binder is a mixture of sodium metaaluminate, sodium silicate and / or silicic acid, and the molar ratio of silicon to aluminum is 1.5-2.5.The preparation method has the advantages of low impurity content of the binder, small environmental pollution, and the 5A molecular sieve adsorbent prepared by the method has the advantages of large adsorption capacity and high strength.

Description

Technical Field

[0001] This invention relates to the field of chemical adsorption and separation technology, specifically to a 5A molecular sieve adsorbent, its preparation method, and its application. Background Technology

[0002] n-Alkanes are important basic chemicals used in the production of detergents, chlorinated paraffins, and plasticizers. The molecular diameter of n-alkanes in petroleum products is less than 0.5 nm, while the molecular diameter of other isoalkanes, cycloalkanes, and aromatics is greater than 0.5 nm. The effective pore size of 5A molecular sieves is 0.5 nm, which can adsorb straight-chain n-alkanes while preventing other hydrocarbons from entering the sieve channels. Based on its adsorption characteristics, 5A molecular sieves can be used as an adsorbent to separate and adsorb n-alkanes from petroleum products.

[0003] CN87105499A discloses a method for preparing binder-free spherical type A molecular sieves. This method uses inorganic ammonium salts, inorganic acids, and water glass as raw materials, and prepares silica hydrogel microspheres using an oil column molding method. After washing with water, impregnation with surfactants, drying, and calcination, low-density silica microspheres are formed. These silica microspheres are then mixed with a sodium aluminate solution and aged and crystallized at a certain temperature, essentially converting the silica into 4A molecular sieves. Further calcium exchange transforms them into 5A molecular sieves. This process introduces two major pollutants during production: the use of inorganic ammonium salts generates difficult-to-treat ammonia nitrogen wastewater, and the use of surfactants causes COD levels in the wastewater to exceed standards, making pollution control challenging.

[0004] CN201310516673.8 discloses a 5A molecular sieve adsorbent, its preparation method, and its application. The method includes: rolling a powder containing a 4A molecular sieve and a binder into small spheres; and drying and calcining the small spheres to obtain matrix spheres. The binder is made of kaolin, diatomaceous earth, etc., and contains impurities such as iron oxide, nickel oxide, and copper oxide, especially with a high iron oxide content. These impurities have certain catalytic activity and, during adsorption and separation operation, may cause a small amount of alkanes to undergo cracking reactions or trace amounts of olefins in oil to undergo superposition reactions. Over time, this may clog some molecular sieve channels, affecting the adsorbent's service life.

[0005] Considering that the general service life of adsorbents is more than 5 years, in order to ensure the long-term and efficient operation of the adsorption separation device, it is necessary to use a new binder with fewer impurities. By optimizing the adsorbent molding method and preparation process, an adsorbent with high strength, high adsorption capacity and long service life can be obtained. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for preparing a 5A molecular sieve adsorbent with low binder impurity content, low environmental pollution, and the advantages of large adsorption capacity and high strength.

[0007] To achieve the above objectives, the present invention provides a method for preparing a 5A molecular sieve adsorbent, the method comprising:

[0008] (1) Powder containing 4A molecular sieve and composite binder is rolled into small balls, and the small balls are dried and calcined to obtain matrix small balls;

[0009] (2) The matrix microspheres are pre-wetted and then calcium exchange is performed to obtain 5A molecular sieve microspheres;

[0010] (3) The 5A molecular sieve microspheres are washed with water, dried, and then calcined to obtain the 5A molecular sieve adsorbent.

[0011] The composite binder is a mixture of sodium aluminate, sodium silicate, and / or silicic acid, with a silicon-to-aluminum molar ratio of 1.5-2.5.

[0012] Preferably, in step (1), the silicon-aluminum molar ratio of the composite adhesive is 1.7-2.3.

[0013] Preferably, in step (1), the average grain diameter of the 4A molecular sieve is 0.01-2.0 μm, and more preferably 0.5-0.9 μm.

[0014] Preferably, in step (1), the methanol adsorption capacity of the 4A molecular sieve is 160-190 mg / g, more preferably 180-190 mg / g.

[0015] Preferably, in step (1), the content of 4A molecular sieve in the powder is 90-99.9% by weight, the content of composite binder is 0.1-10% by weight, and the content of pore-forming agent is 0-7% by weight. More preferably, the content of 4A molecular sieve in the powder is 90-99% by weight, the content of composite binder is 0.1-9% by weight, and the content of pore-forming agent is 0.1-7% by weight.

[0016] Preferably, in step (2), the pre-wetting process results in a water content of 17% by weight or more in the pre-wetted matrix microspheres, more preferably 19-23% by weight.

[0017] Preferably, in step (3), the calcination includes calcining the 5A molecular sieve microspheres under vacuum at a vacuum degree of -(10-100) kPa.

[0018] Preferably, in step (3), the calcination conditions are such that the water content of the calcined 5A molecular sieve microspheres is below 3.5% by weight.

[0019] Preferably, in step (3), the calcination conditions include: a calcination temperature of 200-900℃, preferably 350-550℃; a calcination vacuum of -(10-100)kPa, preferably -(80-95)kPa; and a calcination time of 1-5 hours, preferably 2-3 hours.

[0020] A second aspect of the present invention provides a 5A molecular sieve adsorbent prepared by the preparation method of the first aspect described above.

[0021] Preferably, the hexane adsorption capacity of the 5A molecular sieve adsorbent is 125 mg / g or more, and more preferably 135 mg / g or more.

[0022] The third aspect of the present invention provides the application of the 5A molecular sieve adsorbent of the second aspect above in the adsorption and separation of n-alkanes, preferably in the adsorption and separation of n-hexane.

[0023] Through the above technical solution, this invention obtains matrix microspheres by spheroidizing powder containing 4A molecular sieve and composite binder, followed by drying and calcination. The matrix microspheres are then pre-wetted, subjected to calcium exchange, dried, and calcined. This results in a 5A molecular sieve adsorbent prepared according to this invention exhibiting advantages such as high adsorption capacity, high adsorption efficiency, and good strength for n-alkanes (e.g., n-hexane). Furthermore, the method of this invention is simple, requires no surfactants, and generates no ammonia nitrogen wastewater, thus effectively achieving clean production. Therefore, the method of this invention is environmentally friendly and highly suitable for industrial applications.

[0024] The binder used in this invention has a low impurity content, which helps extend the service life of the adsorbent. Furthermore, this invention employs a vacuum calcination activation method, which further enhances the adsorption capacity of the product.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] This invention provides a method for preparing a 5A molecular sieve adsorbent, the method comprising:

[0028] (1) Powder containing 4A molecular sieve and composite binder is rolled into small balls, and the small balls are dried and calcined to obtain matrix small balls;

[0029] (2) The matrix microspheres are pre-wetted and then calcium exchange is performed to obtain 5A molecular sieve microspheres;

[0030] (3) The 5A molecular sieve microspheres are washed with water, dried, and then calcined to obtain the 5A molecular sieve adsorbent product.

[0031] The composite binder is a mixture of sodium aluminate, sodium silicate, and / or silicic acid, with a silicon-to-aluminum molar ratio of 1.5-2.5.

[0032] According to the method of the present invention, the 4A molecular sieve can be the 4A molecular sieve commonly used in the art for the preparation of 5A molecular sieve adsorbents.

[0033] According to the method of the present invention, the composite binder can be a mixture of sodium aluminate and sodium silicate, a mixture of sodium aluminate and silicic acid, or a mixture of sodium aluminate, sodium silicate, and silicic acid. Furthermore, it is preferred that the content of impurities (e.g., iron oxide, nickel oxide, copper oxide, etc.) in the composite binder is less than 90 ppm.

[0034] From the perspective of further improving the adsorption performance of the obtained 5A molecular sieve adsorbent, preferably, the silicon-aluminum molar ratio of the composite binder is 1.7-2.3.

[0035] The silicon-aluminum molar ratio used as a composite binder can be, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, or 2.5.

[0036] The composite binder is preferably added in the form of an aqueous solution, and the total concentration of sodium aluminate, sodium silicate and / or silicic acid in the composite binder solution is preferably 5-25% by weight, and more preferably 10-20% by weight.

[0037] According to the method of the present invention, the objectives of the present invention can be achieved by following the foregoing technical solutions. Based on this, in order to further improve the n-alkane adsorption capacity of the prepared 5A molecular sieve adsorbent, it is preferable that the average grain diameter of the 4A molecular sieve in step (1) is 0.01-2.0 μm, more preferably 0.5-0.9 μm. Using the aforementioned 4A molecular sieve with the aforementioned average grain diameter to prepare the 5A molecular sieve adsorbent of the present invention can improve the n-alkane adsorption capacity of the prepared 5A molecular sieve adsorbent.

[0038] According to the method of the present invention, more preferably, the methanol adsorption capacity of the 4A molecular sieve in step (1) is 160-190 mg / g, more preferably 180-190 mg / g.

[0039] According to the method of the present invention, preferably, the powder containing 4A molecular sieve and composite binder in step (1) also contains an auxiliary agent (e.g., a pore-forming agent), wherein the pore-forming agent is preferably one or more of lignin, sodium cellulose, and guar gum powder. By adding a pore-forming agent to the powder, the bulk density of the 5A molecular sieve adsorbent can be adjusted, and the formation of secondary pores inside the adsorbent is also facilitated.

[0040] According to the method of the present invention, the content of 4A molecular sieve, composite binder, and optional pore-forming agent in the powder has a wide selectable range. In a preferred embodiment of the present invention, the content of 4A molecular sieve in the powder is 90-99.9% by weight, the content of composite binder is 0.1-10% by weight, and the content of pore-forming agent is 0-7% by weight. In another preferred embodiment of the present invention, the content of 4A molecular sieve in the powder is 90-99% by weight, the content of composite binder is 0.1-9% by weight, and the content of pore-forming agent is 0.1-7% by weight. When using a composite binder solution, the above-mentioned content of composite binder is based on the weight of the composite binder solution.

[0041] In this invention, the method for preparing the powder containing 4A molecular sieve, composite binder, and optional additives can refer to existing methods for preparing 4A molecular sieve matrix microspheres. For example, the 4A molecular sieve powder, composite binder, and optional additive powder can be mixed in a mixer (e.g., a twin-screw mixer) for 0.5-5 hours, preferably 2-3 hours. This is well understood by those skilled in the art, and will not be elaborated further here.

[0042] The method for ball forming of powder containing 4A molecular sieve, composite binder, and optional additives in this invention can refer to existing methods for preparing 4A molecular sieve matrix microspheres. For example, it can be carried out according to the following steps: the powder containing 4A molecular sieve, composite binder, and optional additives is fed into a ball forming pot (e.g., a sugar coating pot), and then ball forming is carried out while adding water. Preferably, the operating conditions in the ball forming pot include: a rotation speed of 30-40 rpm, a water addition rate that increases the total moisture content of the ball forming material by 2-6% by weight per hour, and when the moisture content of the total ball forming material reaches 45-50% by weight, water addition is stopped, and ball forming continues for 1-5 hours at a rotation speed of 40-100 rpm. For this invention, the preferred ball forming conditions result in microspheres with a particle size of 0.1-0.7 mm and a moisture content of 43-45% by weight.

[0043] According to the method of the present invention, the drying and calcining of the microspheres in step (1) can be carried out using existing methods for forming 4A molecular sieve catalysts. Specifically, the drying in step (1) can be carried out under the following conditions: temperature 80-150°C, time 1-10 hours; preferably, temperature 100-130°C, time 1-5 hours. Additionally, the calcination can be carried out under the following conditions: temperature 200-600°C, time 1-5 hours; preferably, temperature 500-600°C, time 1-3 hours.

[0044] According to the method of the present invention, the purpose of the present invention can be achieved as long as the matrix microspheres are pre-wetted before calcium exchange. In order to further improve the n-alkane adsorption capacity of the finally prepared 5A molecular sieve adsorbent, the pre-wetting condition of the matrix microspheres in step (2) is preferably such that the water content in the pre-wetted matrix microspheres is more than 17% by weight, preferably 19-23% by weight.

[0045] According to the method of the present invention, there are no special requirements for the pre-humidification method. As long as the water content in the pre-humidified matrix microspheres is above 17% by weight, the purpose of the present invention can be achieved. Existing pre-humidification methods can all be used in the present invention. For the present invention, the pre-humidification in step (2) is preferably carried out as follows: the matrix microspheres are placed in a certain humidity environment for pre-humidification for 1-10 hours, wherein the ambient humidity is preferably 10-100%RH, more preferably 70-80%RH. Herein, RH refers to relative humidity, specifically the percentage of water vapor content in the air in the environment to the saturated water vapor content in the air under the same conditions.

[0046] According to the method of the present invention, the calcium exchange in step (2) can be carried out with reference to the existing 5A molecular sieve preparation method, and the final calcium exchange rate must be greater than 80%.

[0047] According to the method of the present invention, there are no special requirements for the container used for calcium exchange. For example, it can be carried out in a batch vessel or a column vessel. For the present invention, it is preferred that the calcium exchange be carried out in a column vessel.

[0048] According to the method of the present invention, the method of drying the 5A molecular sieve microspheres in step (3) can be carried out with reference to the existing 5A molecular sieve preparation method, so that the water content of the 5A molecular sieve microspheres is less than 17% by weight.

[0049] According to the method of the present invention, the calcination method of the 5A molecular sieve microspheres in step (3) can be carried out with reference to the existing 5A molecular sieve preparation method. However, the inventors of the present invention found in the research process that if the 5A molecular sieve microspheres are calcined under a certain vacuum degree, the water precipitated during the calcination of the 5A molecular sieve microspheres can be quickly removed, thereby effectively avoiding the damage of the 5A molecular sieve structure to high temperature water vapor and helping to improve the adsorption capacity of the adsorbent. Therefore, for the present invention, it is preferred that the 5A molecular sieve microspheres are calcined under a vacuum degree of -(10-100) kPa in step (3) to activate and dehydrate them, and more preferably the calcination conditions are such that the water content of the calcined 5A molecular sieve microspheres is less than 3.5% by weight. For the present invention, the preferred calcination conditions include: a calcination temperature of 200-900℃, preferably 350-550℃; a calcination vacuum degree of -(10-100) kPa, preferably -(80-95) kPa; and a calcination time of 1-5 hours, preferably 2-3 hours.

[0050] The roasting equipment capable of meeting the aforementioned roasting conditions can be, for example, a vacuum roasting furnace or a vacuum oven. According to the method of the present invention, there are no special requirements for the operating conditions of the roasting furnace, as long as the objective of the present invention can be achieved.

[0051] In this invention, the purpose of washing the 5A molecular sieve microspheres with water in step (3) is mainly to remove chloride ions. This is known to those skilled in the art, and will not be repeated here, nor will it be emphasized in the specific embodiments of this invention.

[0052] The second aspect of the present invention provides a 5A molecular sieve adsorbent prepared by the preparation method of the first aspect of the present invention.

[0053] The hexane adsorption capacity of the 5A molecular sieve adsorbent prepared according to the method of the present invention is above 125 mg / g, preferably above 135 mg / g, for example 127-136 mg / g.

[0054] Furthermore, the 5A molecular sieve adsorbent prepared according to the method of the present invention has a breakage rate of less than 9.1% at 250N.

[0055] A third party has provided the application of the 5A molecular sieve adsorbent described in the second aspect of this invention in the adsorption and separation of n-alkanes, preferably in the adsorption of n-hexane.

[0056] In this invention, the loss on ignition of the 5A molecular sieve adsorbent at 600°C is less than 5% by weight, preferably 2-4% by weight.

[0057] In this invention, the water content of the 5A molecular sieve adsorbent is expressed as the loss on ignition after 1.0 hour at 600°C, which is the ratio of the mass loss of the 5A molecular sieve adsorbent after ignition to the mass of the 5A molecular sieve adsorbent before ignition.

[0058] In this invention, the diameter of the 5A molecular sieve adsorbent is preferably 0.1-0.7 mm, more preferably 0.3-0.5 mm.

[0059] In this invention, the hexane adsorption capacity was determined according to industry standard Q / SH 349 551.

[0060] In this invention, calcium exchange rate refers to the percentage of sodium ions in the molecular sieve that are replaced by calcium ions, which is measured according to the method of industry standard Q / SH349550.

[0061] In this invention, the average grain diameter is measured using scanning electron microscopy.

[0062] In this invention, the adsorbent strength determination method is described in Chinese patent CN1261201C, which is expressed as the breakage rate under 250N pressure. The lower the breakage rate, the better the strength.

[0063] Example 1

[0064] (1) Take 200 kg of commercially available 4A molecular sieve raw powder that has been finely ground (moisture content of 20% by weight, average crystal diameter of 0.7 μm, methanol adsorption capacity of 185 mg / g), 10 kg of sodium aluminate and sodium silicate composite binder solution (total content of sodium aluminate and sodium silicate of 16% by weight, silicon-aluminum molar ratio of 2), and 5 kg of guar gum powder pore-forming agent and put them into a twin-screw mixer and mix for 2 hours. Take out 30 kg of the mixed material and put it into a ball rolling pot (sugar coating pot) with an inlet diameter of 1.0 m to form small balls (the operating conditions in the ball rolling pot include: speed control of 3). Add water at a rate of 5 revolutions per minute, increasing the material's moisture content by 3-5% by weight per hour. When the final moisture content reaches 45-50% by weight, stop adding water and maintain the rolling pot at 50 revolutions per minute for 3-5 hours. When the balls reach a diameter of 0.1-0.7 mm, polish them for 1-2 hours and sieve to obtain small ball samples (moisture content 43% by weight, diameter 0.3-0.7 mm). Dry the small balls in an oven at 100°C for 2 hours, then calcine them in a converter at 550°C for 2 hours, and finally cool them to 20°C to obtain matrix small balls.

[0065] (2) The matrix microspheres are placed in an environment with an air humidity of 70-80%RH to make their water content reach 20% by weight; then the pre-wetted matrix microspheres are sent into a column reactor to contact with calcium chloride aqueous solution for calcium ion exchange. The concentration of calcium chloride aqueous solution is 0.5mol / L, the volume ratio of calcium chloride aqueous solution to 4A molecular sieve matrix microspheres is 2, the contact time is 3.5 hours, and the contact temperature is 95℃. Finally, the calcium exchange rate of 4A molecular sieve matrix microspheres reaches 90%, and 5A molecular sieve microspheres are obtained.

[0066] (3) The 5A molecular sieve microspheres are then washed with water to remove chloride ions, and dried to reduce the water content of the 5A molecular sieve microspheres to below 18% by weight; finally, they are calcined in a vacuum activation furnace (made by Sinopec Nanjing Catalyst Co., Ltd.) to activate and dehydrate (the volume of the vacuum furnace is controlled to be 1.2 m³). 3 The temperature was 500℃, the vacuum degree was -90kPa, and the calcination time was 2 hours to obtain 5A molecular sieve microsphere adsorbent (the water content was reduced to below 3.0% by weight, and the relevant properties such as the adsorption capacity of n-hexane are shown in Table 1).

[0067] Example 2

[0068] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the average crystal diameter of the 4A molecular sieve raw powder used in step (1) was 1.2 μm (water content was 20% by weight, methanol adsorption capacity was 181 mg / g), and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as n-hexane adsorption capacity are shown in Table 1).

[0069] Example 3

[0070] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1. The difference was that the average crystal diameter of the 4A molecular sieve raw powder used in step (1) was 0.6 μm (water content was 21% by weight, methanol adsorption capacity was 181 mg / g), and the pre-wetting conditions of the matrix microspheres in step (2) were such that the water content of the pre-wetted matrix microspheres was 18% by weight. All other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as n-hexane adsorption capacity are shown in Table 1).

[0071] Example 4

[0072] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1. The difference was that the average crystal diameter of the 4A molecular sieve raw powder used in step (1) was 1.7 μm (water content was 21% by weight, methanol adsorption capacity was 181 mg / g), and the other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as n-hexane adsorption capacity are shown in Table 1).

[0073] Example 5

[0074] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that 7 kg of composite binder was used in step (1), and all other conditions were the same, to obtain 5A molecular sieve microsphere adsorbents (related properties such as hexane adsorption capacity are shown in Table 1).

[0075] Example 6

[0076] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the silicon-aluminum molar ratio of the composite binder in step (1) was 1.7, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as the hexane adsorption capacity are shown in Table 1).

[0077] Example 7

[0078] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the silicon-aluminum molar ratio of the composite binder in step (1) was 2.3, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as the hexane adsorption capacity are shown in Table 1).

[0079] Example 8

[0080] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the silicon-aluminum molar ratio of the composite binder in step (1) was 1.5, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as the hexane adsorption capacity are shown in Table 1).

[0081] Example 9

[0082] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the silicon-aluminum molar ratio of the composite binder in step (1) was 2.5, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as the hexane adsorption capacity are shown in Table 1).

[0083] Comparative Example 1

[0084] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that step (2) was not pre-wetted and ion exchange was performed directly. All other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as hexane adsorption capacity are shown in Table 1).

[0085] Comparative Example 2

[0086] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the binder used in step (1) was only sodium silicate, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as n-hexane adsorption capacity are shown in Table 1).

[0087] Comparative Example 3

[0088] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the binder used in step (1) was only sodium aluminate, and the other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as the hexane adsorption capacity are shown in Table 1).

[0089] Comparative Example 4

[0090] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the silicon-aluminum molar ratio of the composite binder in step (1) was 1.2, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as the hexane adsorption capacity are shown in Table 1).

[0091] Comparative Example 5

[0092] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the silicon-aluminum molar ratio of the composite binder in step (1) was 2.8, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (related properties such as the hexane adsorption capacity are shown in Table 1).

[0093] Table 1

[0094]

[0095] As can be seen from the results in the table, the n-hexane adsorption capacity of the 5A molecular sieve adsorbent microspheres prepared according to the method of the present invention is above 125 mg / g, preferably above 134 mg / g, which is much higher than the n-hexane adsorption capacity of the 5A molecular sieve adsorbent microspheres prepared in the comparative example not according to the method of the present invention, and the adsorption strength is also much higher.

[0096] Therefore, the 5A molecular sieve adsorbent microspheres prepared by the method of the present invention are particularly suitable for use as n-alkane adsorbents.

[0097] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0098] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction.

[0099] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a 5A molecular sieve adsorbent, characterized in that, The preparation method includes: (1) The powder containing 4A molecular sieve and composite binder is rolled into small balls, and the small balls are dried and calcined to obtain matrix small balls; (2) The matrix microspheres are pre-wetted and then subjected to calcium exchange to obtain 5A molecular sieve microspheres; (3) The 5A molecular sieve microspheres are washed with water, dried, and then calcined to obtain the 5A molecular sieve adsorbent; The composite binder is a mixture of sodium aluminate and sodium silicate and / or silicic acid, and the silicon-aluminum molar ratio is 1.7-2.

3. In step (1), the content of 4A molecular sieve in the powder is 90-99.9% by weight, the content of composite binder is 0.1-10% by weight, and the content of pore-forming agent is 0-7% by weight; in step (3), the calcination includes calcining the 5A molecular sieve microspheres under vacuum at a vacuum degree of -(10-100) kPa.

2. The preparation method according to claim 1, wherein, In step (1), the average grain diameter of the 4A molecular sieve is 0.01-2.0 μm.

3. The preparation method according to claim 2, wherein, In step (1), the average grain diameter of the 4A molecular sieve is 0.5-0.9 μm.

4. The preparation method according to claim 1, wherein, The methanol adsorption capacity of the 4A molecular sieve is 160-190 mg / g.

5. The preparation method according to claim 4, wherein, The methanol adsorption capacity of the 4A molecular sieve is 180-190 mg / g.

6. The preparation method according to claim 1, wherein, The powder contains 90-99% by weight of 4A molecular sieve, 0.1-9% by weight of composite binder, and 0.1-7% by weight of pore-forming agent.

7. The preparation method according to any one of claims 1-6, wherein, In step (2), the pre-wetting process ensures that the water content in the pre-wetted matrix microspheres is 17% by weight or more.

8. The preparation method according to claim 7, wherein, In step (2), the pre-wetting process results in a water content of 19-23% by weight in the pre-wetted matrix microspheres.

9. The preparation method according to any one of claims 1-6, wherein, The calcination conditions ensure that the water content of the calcined 5A molecular sieve microspheres is below 3.5% by weight.

10. The preparation method according to claim 1, wherein, In step (3), the calcination conditions include: a calcination temperature of 200-900℃; a calcination vacuum of -(10-100)kPa; and a calcination time of 1-5 hours.

11. The preparation method according to claim 10, wherein, In step (3), the calcination conditions include: a calcination temperature of 350-550℃; a calcination vacuum of -(80-95)kPa; and a calcination time of 2-3 hours.

12. The 5A molecular sieve adsorbent prepared by the preparation method according to any one of claims 1-11.

13. The 5A molecular sieve adsorbent according to claim 12, wherein, The hexane adsorption capacity of the 5A molecular sieve adsorbent is above 125 mg / g.

14. The 5A molecular sieve adsorbent according to claim 13, wherein, The hexane adsorption capacity of the 5A molecular sieve adsorbent is above 135 mg / g.

15. The application of the 5A molecular sieve adsorbent according to any one of claims 12-14 in the adsorption and separation of n-alkanes.

16. The application of the 5A molecular sieve adsorbent according to any one of claims 12-14 in the adsorption and separation of n-hexane.

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