5A Molecular Sieve Adsorbent, Its Preparation Method and Application

Abstract

This invention relates to the field of chemical adsorption and separation technology, and discloses a 5A molecular sieve adsorbent, its preparation method, and its application. The preparation method includes: (1) rolling a powder containing 4A molecular sieve and a binder into small balls, and drying and calcining the small balls to obtain matrix small balls; (2) pre-wetting the matrix small balls and then performing crystallization to obtain 4A molecular sieve small balls; (3) sequentially contacting the 4A molecular sieve small balls with inorganic acid and organic acid, washing with water, and then performing calcium exchange to obtain 5A molecular sieve small balls; (4) washing and drying the 5A molecular sieve small balls, and then performing vacuum calcination to obtain the 5A molecular sieve adsorbent. The preparation method of this invention has a relatively simple process, low water consumption, and the prepared 5A molecular sieve adsorbent has good adsorption capacity and 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 saturated hydrocarbons without carbon branches. They are important chemicals used in the production of detergent raw materials, chlorinated paraffins, cosmetics, daily necessities diluents, and solvents. 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] CN201310516673.8 discloses a method for preparing 5A adsorbents using a spheroidizing process. The method involves spheroidizing powder containing 4A molecular sieves and a binder, followed by drying and calcination to obtain matrix spheres. These matrix spheres are then pre-wetted, crystallized, washed with water, and finally subjected to calcium exchange to obtain the 5A molecular sieve adsorbent. However, this water washing method consumes a significant amount of water, approximately 70 tons per ton of product.

[0004] Therefore, it is necessary to invent a new water washing method that reduces water consumption, improves efficiency, and enhances product performance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing 5A molecular sieve adsorbents that is relatively simple in process, has low water consumption, and produces 5A molecular sieve adsorbents with stable adsorption capacity, strength, and other key indicators.

[0006] The inventors of this invention conducted in-depth research on existing methods for preparing 5A molecular sieve adsorbents and discovered that the purpose of washing with water after obtaining 4A molecular sieve microspheres through crystallization is to remove the influence of sodium hydroxide introduced during the crystallization process. This is because soluble calcium salts are typically used for ion exchange; if the sodium hydroxide is not completely removed during washing, a large amount of calcium hydroxide will be generated. Calcium hydroxide is only slightly soluble, which will inevitably affect the calcium ion exchange efficiency. To address this, the inventors creatively discovered that by contacting inorganic and organic acids separately before washing with water, hydroxide ions can be rapidly neutralized while ensuring the stability of the adsorbent performance, thus completing this invention.

[0007] Specifically, the present invention provides a method for preparing a 5A molecular sieve adsorbent, the method comprising:

[0008] (1) Powder containing 4A molecular sieve and 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 crystallized to obtain 4A molecular sieve microspheres;

[0010] (3) The 4A molecular sieve microspheres are sequentially contacted with inorganic acid and organic acid, washed with water, and then subjected to calcium exchange to obtain 5A molecular sieve microspheres.

[0011] (4) The 5A molecular sieve microspheres are washed with water and dried, and then vacuum calcined to obtain the 5A molecular sieve adsorbent.

[0012] 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.

[0013] Preferably, in step (1), the methanol adsorption capacity of the 4A molecular sieve is 160-190 mg / g, more preferably 180-190 mg / g.

[0014] Preferably, in step (1), the binder is one or more of kaolin, argillaceous earth, and diatomaceous earth.

[0015] Preferably, in step (1), the powder further contains a pore-forming agent, and more preferably, the pore-forming agent is one or more of lignin, sodium cellulose and guar gum powder.

[0016] Preferably, in step (1), the content of 4A molecular sieve in the powder is 90-99.9% by weight, the content of 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 90-99.8% by weight, the content of binder is 0.1-9.9% by weight, and the content of pore-forming agent is 0.1-7% by weight.

[0017] Preferably, in step (2), the pre-wetting process results in a water content of 19% by weight or more in the pre-wetted matrix microspheres, more preferably 20-23% by weight.

[0018] Preferably, in step (3), the inorganic acid is nitric acid or hydrochloric acid, and the organic acid is formic acid or acetic acid.

[0019] Preferably, in step (3), the concentration of the inorganic acid is 0.1-1M and the concentration of the organic acid is 0.1-2M; more preferably, the concentration of the inorganic acid is 0.5-1M and the concentration of the organic acid is 1-1.5M.

[0020] Preferably, in step (3), the process of contacting the 4A molecular sieve microspheres with inorganic acid and organic acid is carried out independently at 10-50°C, preferably at 20-50°C.

[0021] Preferably, in step (4), the 5A molecular sieve microspheres are vacuum calcined under a vacuum of -(10-100) kPa.

[0022] Preferably, in step (4), the calcination conditions are such that the water content of the calcined 5A molecular sieve microspheres is below 3.5% by weight.

[0023] Preferably, in step (4), the calcination conditions include: a calcination temperature of 250-900℃, 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.

[0024] 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 described above.

[0025] Preferably, the hexane adsorption capacity of the 5A molecular sieve adsorbent is 130 mg / g or more, and more preferably 136 mg / g or more.

[0026] The third aspect of the present invention provides the application of the 5A molecular sieve adsorbent described in the second aspect of the present invention in the adsorption and separation of n-alkanes, preferably in the adsorption and separation of n-hexane.

[0027] The preparation method of this invention results in a 5A molecular sieve adsorbent with advantages such as high adsorption capacity, high adsorption efficiency, and good adsorption strength for n-alkanes (e.g., n-hexane). Furthermore, the preparation process employs a combination of inorganic and organic acids, which significantly reduces water consumption, thereby effectively achieving clean production. Therefore, the method of this invention is relatively environmentally friendly and highly suitable for industrial applications. This invention also utilizes a vacuum drying activation method to ensure the adsorption capacity of the product.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0029] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0030] 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.

[0031] This invention provides a method for preparing a 5A molecular sieve adsorbent, the method comprising:

[0032] (1) Powder containing 4A molecular sieve and binder is rolled into small balls, and the small balls are dried and calcined to obtain matrix small balls;

[0033] (2) The matrix microspheres are pre-wetted and then crystallized to obtain 4A molecular sieve microspheres;

[0034] (3) The 4A molecular sieve microspheres are sequentially contacted with inorganic acid and organic acid, washed with water, and then subjected to calcium exchange to obtain 5A molecular sieve microspheres.

[0035] (4) The 5A molecular sieve microspheres are washed with water and dried, and then vacuum calcined to obtain the adsorbent product.

[0036] According to the method of the present invention, the 4A molecular sieve and binder can be the same 4A molecular sieve and binder commonly used in the art for the preparation of 5A molecular sieve adsorbents. For example, the 4A molecular sieve can be a commercially available or homemade 4A molecular sieve; the binder can be one or more of kaolin, argillaceous earth, and diatomaceous earth.

[0037] According to the method of the present invention, the objective of the present invention can be achieved according to the aforementioned technical solution. Based on this, in order to further improve the n-alkane adsorption performance of the prepared 5A molecular sieve adsorbent, it is preferred 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 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 facilitated, which in turn facilitates the diffusion of the adsorption medium.

[0040] According to the method of the present invention, the content of 4A molecular sieve, 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 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 90-99.8% by weight, the content of binder is 0.1-10% by weight, and the content of pore-forming agent is 0.1-7% by weight.

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

[0042] The method for spheronizing powder containing 4A molecular sieve, 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 as follows: the powder containing 4A molecular sieve, binder, and optional additives is fed into a spheronizing pot (e.g., a sugar-coating pot) or other granulation equipment, and then spheronizing is performed while adding water. Preferably, the operating conditions in the spheronizing pot include: a rotation speed of 30-60 rpm, a water addition rate that increases the total moisture content of the spheroning material by 3-6% by weight per hour, and stopping water addition when the total moisture content of the spheroning material reaches 45-55% by weight. For this invention, the preferred spheronizing conditions result in a microsphere size of 0.1-0.7 mm, preferably 0.3-0.7 mm.

[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 crystallization. In order to further improve the n-alkane adsorption capacity of the 5A molecular sieve adsorbent finally prepared, 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 19% by weight, preferably 20-23% 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 19% 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, crystallization is used to substantially convert the binder in the matrix microspheres into 4A molecular sieve, thereby obtaining 4A molecular sieve microspheres.

[0047] According to the method of the present invention, as long as the 4A molecular sieve microspheres are rapidly treated with inorganic acid and organic acid respectively before calcium exchange of the matrix microspheres, and then washed with water, the purpose of the present invention can be achieved.

[0048] According to the method of the present invention, preferably, the inorganic acid in step (3) is nitric acid or hydrochloric acid, and the organic acid is formic acid or acetic acid. The concentration of the inorganic acid is preferably 0.1-1M, more preferably 0.5-1M. The concentration of the organic acid is 0.1-2M, more preferably 1-1.5M. In order to improve the n-hexane adsorption capacity of the obtained 5A molecular sieve adsorbent, it is preferable that the contact process between the 4A molecular sieve microspheres and the inorganic acid and the organic acid is carried out independently at 10-50°C, preferably 20-50°C. In addition, the contact time can be 5-15 minutes, preferably 8-12 minutes.

[0049] In addition, it is preferable to wash the 4A molecular sieve microspheres with water between inorganic acid and organic acid treatment.

[0050] According to some preferred embodiments of the present invention, the acid treatment is divided into two steps: the first step is to soak in an inorganic acid with a concentration of 0.1-1M for 5-15 minutes at a soaking temperature of 10-60°C, and then wash with water 2-3 times; the second step is to soak in an organic acid with a concentration of 0.1-2M for 5-15 minutes at a soaking temperature of 10-60°C, and then wash with water 2-3 times.

[0051] According to the method of the present invention, the calcium exchange in step (3) 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%. The present invention has no special requirements for the container used for the 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.

[0052] According to the method of the present invention, the method of drying the 5A molecular sieve microspheres in step (4) 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 16% by weight.

[0053] According to the method of the present invention, the calcination method of the 5A molecular sieve microspheres in step (4) 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 (4) 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 250-900℃, 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.

[0054] 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.

[0055] In this invention, the purpose of acid treatment of the 4A molecular sieve microspheres in step (3) is mainly to remove free hydroxide ions, and the purpose of water washing of the 5A molecular sieve microspheres in step (4) is mainly to remove chloride ions. Those skilled in the art will know this, and this invention will not elaborate further here, nor will it be emphasized in the specific embodiments of this invention.

[0056] The second aspect of the present invention provides a 5A molecular sieve adsorbent prepared by the method of the first aspect of the present invention.

[0057] The hexane adsorption capacity of the 5A molecular sieve adsorbent prepared according to the method of the present invention is above 130 mg / g, preferably above 136 mg / g, for example 130-137 or 135-137 mg / g.

[0058] Furthermore, the 5A molecular sieve adsorbent prepared according to the method of the present invention has a breakage rate of less than 7% at 250N.

[0059] 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.

[0060] In this invention, the loss on ignition of the 5A molecular sieve adsorbent at 600°C is less than 5% by mass, preferably 2-4% by mass.

[0061] 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.

[0062] 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.

[0063] In this invention, the hexane adsorption capacity was determined according to industry standard Q / SH 349 551.

[0064] 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.

[0065] In this invention, the average grain diameter is measured using scanning electron microscopy.

[0066] 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.

[0067] Example 1

[0068] (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 kaolin, and 3 kg of guar gum powder and put them into a twin-screw mixer and mix for 2 hours. Take out 50 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 roll and form small balls (the operating conditions in the ball rolling pot include: the speed is controlled at 36 rpm, and the water addition rate is based on the material moisture content increasing by 3-5% by weight per hour). When the ball grows to a diameter of 0.1-0.8 mm, polish it for 1 hour and sieve to obtain small ball samples (moisture content of 43% by weight, diameter of 0.3-0.7 mm).

[0069] (2) The microspheres were dried in an oven at 120°C for 2 hours, and then calcined in a converter at 550°C for 2 hours. After cooling to 20°C, the matrix microspheres were 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 were sent into a synthesis vessel and contacted with sodium hydroxide aqueous solution for low-temperature crystallization treatment (wherein, the volume ratio of sodium hydroxide aqueous solution to the pre-wetted matrix microspheres was 2.5, the concentration of sodium hydroxide aqueous solution was 0.2mol / L, the temperature was 50°C, and the time was 2 hours), so that most of the binder was converted into 4A molecular sieve (about 80% by weight of the binder was converted into 4A molecular sieve), and 4A molecular sieve microspheres were obtained. The obtained molecular sieve microspheres were subjected to acid treatment, which consisted of two steps. The first step was to soak in 0.5M nitric acid for 10 minutes at a soaking temperature of 20°C, and then wash with water twice. The second step was to soak in 1.0M acetic acid for 10 minutes at a soaking temperature of 20°C, and then wash with water three times.

[0070] (3) The washed matrix microspheres are fed into a column reactor and contacted with calcium chloride aqueous solution to carry out calcium ion exchange. The concentration of calcium chloride aqueous solution is 0.5 mol / L, the volume ratio of calcium chloride aqueous solution to the washed 4A molecular sieve 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 microspheres reaches 85%, and 5A molecular sieve microspheres are obtained.

[0071] (4) The 5A molecular sieve microspheres are washed with water to remove chloride ions, and then 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 are shown in Table 1).

[0072] Example 2

[0073] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the soaking temperature in step (2) was 50°C, while the other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (the relevant properties are shown in Table 1).

[0074] Example 3

[0075] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the nitric acid concentration in step (2) was 1.0 M, and all other conditions were the same, resulting in 5A molecular sieve microsphere adsorbents (related properties are shown in Table 1).

[0076] Example 4

[0077] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the soaking temperature in step (2) was 10°C, while the other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (the relevant properties are shown in Table 1).

[0078] Example 5

[0079] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the acetic acid concentration in step (2) was 1.5M, and all other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (the relevant properties are shown in Table 1).

[0080] Example 6

[0081] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that the nitric acid concentration in step (2) was 0.2M, and all other conditions were the same, resulting in 5A molecular sieve microsphere adsorbents (related properties are shown in Table 1).

[0082] Comparative Example 1

[0083] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that in step (2), the microspheres were soaked in 0.5M nitric acid for 10 minutes at a temperature of 20°C and then washed twice with water. All other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (the relevant properties are shown in Table 1).

[0084] Comparative Example 2

[0085] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that in step (2), the microspheres were soaked in 1.0M acetic acid for 10 minutes at a temperature of 20°C and then washed twice with water. All other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (the relevant properties are shown in Table 1).

[0086] Comparative Example 3

[0087] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that in step (2), the microspheres were first soaked in acetic acid, washed with water, and then soaked in nitric acid. All other conditions were the same, and 5A molecular sieve microsphere adsorbents were obtained (the relevant properties are shown in Table 1).

[0088] Comparative Example 4

[0089] 5A molecular sieve adsorbent microspheres were prepared according to the method of Example 1, except that acid treatment was not performed in step (2), and all other conditions were the same, to obtain 5A molecular sieve microsphere adsorbents (related properties are shown in Table 1).

[0090] Table 1

[0091]

[0092] As can be seen from the results in Table 1, the n-hexane adsorption capacity of the 5A molecular sieve adsorbent microspheres prepared according to the method of the present invention is above 130 mg / g, preferably above 135 mg / g. This 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 preparation efficiency is also much higher.

[0093] Therefore, the 5A molecular sieve adsorbent microspheres prepared by the method of the present invention are particularly suitable for use as n-alkane adsorbents.

[0094] 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.

[0095] 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.

[0096] 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 method includes: (1) Powder containing 4A molecular sieve and 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 crystallized to obtain 4A molecular sieve microspheres; (3) The 4A molecular sieve microspheres are sequentially contacted with inorganic acid and organic acid, washed with water, and then subjected to calcium exchange to obtain 5A molecular sieve microspheres; (4) The 5A molecular sieve microspheres are washed with water and dried, and then vacuum calcined to obtain the 5A molecular sieve adsorbent; In step (3), the inorganic acid is nitric acid or hydrochloric acid, and the organic acid is formic acid or acetic acid; The concentration of the inorganic acid is 0.5-1M, and the concentration of the organic acid is 1-1.5M; The processes of contacting 4A molecular sieve microspheres with inorganic and organic acids are carried out independently at 20-50℃.

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; And / or, the methanol adsorption capacity of the 4A molecular sieve is 160-190 mg / g.

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; And / or, the methanol adsorption capacity of the 4A molecular sieve is 180-190 mg / g.

4. The preparation method according to claim 1, wherein, In step (1), the binder is one or more of kaolin, argillaceous earth and diatomaceous earth.

5. The preparation method according to claim 1, wherein, The powder also contains a pore-forming agent; And / or, the content of 4A molecular sieve in the powder is 90-99.9% by weight, the content of binder is 0.1-10% by weight, and the content of pore-forming agent is 0-7% by weight.

6. The preparation method according to claim 5, wherein, The pore-forming agent is one or more of lignin, sodium cellulose, and guar gum powder; And / or, the content of 4A molecular sieve in the powder is 90-99.8% by weight, the content of binder is 0.1-9.9% by weight, and the content of pore-forming agent is 0.1-7% by weight.

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 19% 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 20-23% by weight in the pre-wetted matrix microspheres.

9. The preparation method according to any one of claims 1-6, wherein, In step (4), the 5A molecular sieve microspheres are vacuum calcined under a vacuum of -(10-100) kPa.

10. 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.

11. The preparation method according to claim 9, wherein, The calcination conditions include: a calcination temperature of 250-900℃; a calcination vacuum of -(10-100) kPa; and a calcination time of 1-5 hours.

12. The preparation method according to claim 11, wherein, 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.

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

14. The 5A molecular sieve adsorbent according to claim 13, wherein, The hexane adsorption capacity of the 5A molecular sieve adsorbent is above 130 mg / g.

15. The 5A molecular sieve adsorbent according to claim 14, wherein, The hexane adsorption capacity of the 5A molecular sieve adsorbent is above 136 mg / g.

16. The application of the 5A molecular sieve adsorbent according to any one of claims 13-15 in the adsorption and separation of n-alkanes.

17. The application according to claim 16, wherein, The application of the 5A molecular sieve adsorbent in the adsorption and separation of n-hexane.

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