阅读说明：本技术 一种无结构导向剂动态合成的kl分子筛及其制备方法 (KL molecular sieve dynamically synthesized by structureless directing agent and preparation method thereof ) 是由 陈会民 李珂 王苹 王海丽 丁湘浓 王熙 于 2021-09-03 设计创作，主要内容包括：本发明公开了一种无结构导向剂动态合成的KL分子筛及其制备方法。制备方法是将氢氧化钾、铝源、硅源和水按(4～7)：1：(12.0～18.0)：(150～350)的摩尔比混合,搅拌陈化后在动态水热条件下晶化,然后经分离、洗涤、干燥后得到KL分子筛。本发明与KL分子筛其他合成方法相比,无需加入有机醇类、晶种或金属离子类结构导向剂,仅需调变体系碱度和硅铝比,方法简单,且采用动态合成条件,易于进行工业放大和KL分子筛的大规模批量生产。(The invention discloses a KL molecular sieve dynamically synthesized by a structureless directing agent and a preparation method thereof. The preparation method comprises the following steps of mixing potassium hydroxide, an aluminum source, a silicon source and water according to the ratio of (4-7): 1: (12.0-18.0): (150-350), stirring and aging, crystallizing under a dynamic hydrothermal condition, and then separating, washing and drying to obtain the KL molecular sieve. Compared with other synthesis methods of the KL molecular sieve, the method does not need to add organic alcohols, seed crystals or a metal ion structure directing agent, only needs to adjust the system alkalinity and the silicon-aluminum ratio, is simple, adopts dynamic synthesis conditions, and is easy to carry out industrial amplification and large-scale batch production of the KL molecular sieve.)

1. A method for dynamically synthesizing a KL molecular sieve without a structure directing agent is characterized by comprising the following steps:

(1) and fully mixing potassium hydroxide, an aluminum source and water, heating to obtain a clear solution, adding a silicon source, stirring and aging to obtain the initial synthetic sol.

(2) And (3) placing the initial synthetic sol in a crystallization kettle for hydrothermal crystallization, and then sequentially separating, washing and drying crystallized products.

2. The method according to claim 1, wherein the method comprises the following steps: the aluminum source is aluminum hydroxide, pseudo-boehmite, aluminum nitrate, aluminum sulfate, aluminum isopropoxide or potassium aluminate; the silicon source is silica sol, ethyl orthosilicate or water glass.

3. The method according to claim 1, wherein the method comprises the following steps: in the step (1), the feeding molar ratio of potassium hydroxide, an aluminum source, a silicon source and water is (4-7): 1: (12.0-18.0): (150-350).

4. The method according to claim 1, wherein the method comprises the following steps: the heating temperature in the step (1) is 70-150 ℃, and the time is 0.5-24 hours.

5. The method according to claim 1, wherein the method comprises the following steps: in the step (1), the stirring and aging temperature is 10-80 ℃, and the time is 8-24 hours.

6. The method according to claim 1, wherein the method comprises the following steps: the size of the crystallization kettle in the step (2) is 50 mL-10L.

7. The method according to claim 1, wherein the method comprises the following steps: the hydrothermal crystallization in the step (2) is dynamic hydrothermal crystallization, the rotating speed is 10-400 r/min, the temperature is 160-180 ℃, and the time is 12-48 h.

8. The method according to claim 1, wherein the method comprises the following steps: in the step (2), the separation is suction filtration or centrifugal separation, and the washing is carried out until the pH value of the washing liquid is 7-9.

9. The method according to claim 1, wherein the method comprises the following steps: in the step (2), the drying temperature is 100-200 ℃, and the drying time is 12-24 hours.

10. The KL molecular sieve prepared by the method for dynamically synthesizing the KL molecular sieve without the structure directing agent according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of molecular sieves, in particular to a KL molecular sieve dynamically synthesized by a structureless directing agent and a preparation method thereof.

Background

KL molecular sieve with topological structure of LTL is light hydrocarbon aromatization alkaline catalystThe commonly used carrier is firstly developed and synthesized by Union Carbide company in 1965, has a one-dimensional twelve-membered ring channel structure with the channel size of 0.71nm, belongs to a hexagonal system (P6/mmm, ) The Pt/KL catalyst has good hydrothermal stability, and the Pt/KL catalyst loaded with noble metal shows excellent activity and aromatization selectivity in light hydrocarbon aromatization reaction, particularly in C5-C8 straight chain paraffin aromatization reaction.

The KL molecular sieve is synthesized by mainly adopting a hydrothermal crystallization method, and synthesizing the KL molecular sieve by using a silicon source, an aluminum source, water and a structure directing agent (seed crystal, metal ions, a template agent and the like) through static hydrothermal in a strong alkaline system. However, the static hydrothermal synthesis is greatly limited due to the heat transfer problem under the industrial scale-up condition (such as the cubic level), and is not favorable for the large-scale mass production of the KL molecular sieve. Based on this, the development of a dynamic hydrothermal synthesis method of KL molecular sieves is essential.

Both the Chinese patent with publication number CN106395851B and the Chinese patent application with publication number CN108033462A disclose methods for synthesizing KL molecular sieves by using a structure directing agent, wherein the Chinese patent with publication number CN106395851B discloses that Ba is added into a synthesis system²⁺And a KL molecular sieve is dynamically synthesized by using a method of low-carbon monohydric alcohol (methanol, ethanol, propanol or butanol); and the Chinese patent application with the publication number of CN108033462A discloses that a KL molecular sieve is dynamically synthesized by adding polyethylene glycol. However, the addition of the structure directing agent increases the difficulty of the post-treatment of the KL molecular sieve (if organic alcohol is added, the KL molecular sieve needs to be removed by high-temperature roasting), and increases the synthesis cost.

Disclosure of Invention

The invention aims to provide a KL molecular sieve dynamically synthesized by a non-structural targeting agent and a preparation method thereof aiming at the defects of the prior art. According to the method, various organic alcohol or metal ion structure directing agents are not required to be added in the dynamic synthesis process, and the dynamic synthesis of the structureless directing agent of the KL molecular sieve can be realized only by regulating and controlling the alkalinity and the silicon-aluminum ratio of a system.

In order to achieve the purpose of the invention, the invention adopts the technical scheme that: a method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps:

(1) and fully mixing potassium hydroxide, an aluminum source and water, heating to obtain a clear solution, adding a silicon source, stirring and aging to obtain the initial synthetic sol.

(2) And transferring the initial synthetic sol to crystallization kettles with different sizes for hydrothermal crystallization, and then sequentially separating, washing and drying crystallized products to obtain the KL molecular sieve.

In the step (1), the aluminum source is aluminum hydroxide, pseudo-boehmite, aluminum nitrate, aluminum sulfate, aluminum isopropoxide or potassium aluminate, and preferably aluminum hydroxide; the silicon source is silica sol, ethyl orthosilicate or water glass, and preferably silica sol.

In the step (1), the feeding molar ratio of the potassium hydroxide to the aluminum source to the silicon source to the water is (4-7): 1: (12.0-18.0): (150 to 350); the preferable feeding molar ratio is (5-6): 1: (14.0-16.0): (150-350).

In the step (1), the heating temperature can be 70-150 ℃, and the time can be 0.5-24 hours.

The stirring and aging temperature in the step (1) can be 10-80 ℃, and the time can be 8-24 h.

The size of the crystallization kettle in the step (2) can be 50 mL-10L.

In the step (2), the crystallization temperature is 160-180 ℃, and the time is 12-48 h; the preferred crystallization temperature is 175 ℃ and the time is 24 h.

The hydrothermal crystallization in the step (2) is dynamic hydrothermal crystallization, and the rotating speed is 10-400 r/min.

And (3) performing suction filtration or centrifugal separation in the step (2), and washing until the pH value of a washing liquid is 7-9.

In the step (2), the drying temperature is 100-200 ℃, and the drying time is 12-24 hours.

Compared with the prior art, the invention has the following advantages and effects:

(1) the KL molecular sieve prepared by the method has better purity and crystallinity.

(2) The synthesis method provided by the invention is simple, organic alcohols, seed crystals or metal ion structure directing agents are not required to be added, and only the system alkalinity and the silicon-aluminum ratio are required to be adjusted.

(3) The invention adopts a dynamic hydrothermal crystallization method, and is easy to carry out industrial amplification and large-scale batch production of the KL molecular sieve.

Drawings

FIG. 1 is an XRD spectrum of KL molecular sieve prepared in example 1 of the present invention.

Figure 2 is an XRD spectrum of KL molecular sieve prepared in example 2 of the present invention.

Figure 3 is an SEM photograph of KL molecular sieve prepared in example 2 of the present invention.

FIG. 4 shows N of KL molecular sieve prepared in example 2 of the present invention₂Adsorption and desorption isotherms.

Figure 5 is an XRD spectrum of KL molecular sieve prepared in example 3 of the present invention.

Figure 6 is an XRD spectrum of KL molecular sieve prepared in example 4 of the present invention.

Figure 7 is an XRD spectrum of KL molecular sieve prepared in example 5 of the present invention.

Figure 8 is an XRD spectrum of KL molecular sieve prepared in example 6 of the present invention.

Figure 9 is an SEM photograph of KL molecular sieve prepared in example 6 of the present invention.

Figure 10 is an XRD spectrum of KL molecular sieve prepared in example 7 of the present invention.

Figure 11 is an XRD spectrum of KL molecular sieve prepared in example 8 of the present invention.

Figure 12 is an XRD spectrum of KL molecular sieve prepared in example 9 of the present invention.

Detailed Description

The technical scheme of the present invention will be described in detail with reference to specific examples, and unless otherwise specified, experimental devices, materials, reagents, and the like used in the examples are commercially available.

Example 1

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: weighing 19.52g KOH dissolved in a small amount of water, then adding 4.50g Al (OH)₃Heating to 100 ℃ in a three-neck flask, stirring and refluxing for 2h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 88.84g of silica Sol (SiO) was weighed₂Content of 30 wt.%) is slowly added into the above-mentioned solution, stirred and aged for 20h at room temperature so as to obtain KL molecular sieve initial synthetic sol, and the mole ratio of all the materials in said initial synthetic sol is 5.0K₂O：15.0SiO₂：1.0Al₂O₃：292.65H₂And O. And transferring the initial synthetic sol to a 200mL polytetrafluoroethylene lining, filling the polytetrafluoroethylene lining into a stainless steel crystallization kettle, performing dynamic hydrothermal crystallization in a homogeneous reactor at 175 ℃ at the rotating speed of 10r/min for 24 hours, performing suction filtration and deionized water washing on the obtained product to neutrality, and drying at 120 ℃ for 24 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 1, and the obtained product is the KL molecular sieve.

Example 2

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 21.47g KOH was weighed out and dissolved in a small amount of water, then 4.50g Al (OH) were added₃Heating to 100 ℃ in a three-neck flask, stirring and refluxing for 2h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 88.84g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at room temperature for 16h to obtain KL molecular sieve initial synthetic sol, in which the molar ratio of each material was 5.5K₂O：15.0SiO₂：1.0Al₂O₃：292.65H₂And O. And transferring the initial synthetic sol to a 200mL polytetrafluoroethylene lining, filling the polytetrafluoroethylene lining into a stainless steel crystallization kettle, performing dynamic hydrothermal crystallization in a homogeneous reactor at 175 ℃ at a rotating speed of 15r/min for 24 hours, centrifuging the obtained product, washing the product with deionized water to be neutral, and drying the product at 120 ℃ for 24 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 2, and the obtained product is the KL molecular sieve. The SEM image of the obtained sample is shown in FIG. 3, and the result shows that all the obtained KL molecular sieves are spindle-shaped and have the size of about 600 nm. N of the obtained sample₂The adsorption and desorption isotherms are shown in fig. 4, table 1 shows the texture properties of the obtained samples, and the results show that the BET specific surface area of the prepared KL molecular sieve reaches 325m²/g。

Table 1 shows the texture properties of KL molecular sieve prepared in example 2 of the present invention

Example 3

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 23.42g KOH were weighed out and dissolved in a small amount of water, then 4.50g Al (OH) were added₃Heating to 100 ℃ in a three-neck flask, stirring and refluxing for 2h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 88.84g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at room temperature for 20 hours to obtain KL molecular sieve initial synthetic sol, in which the molar ratio of each material was 6.0K₂O：15.0SiO₂：1.0Al₂O₃：292.65H₂And O. And transferring the initial synthetic sol to a 200mL polytetrafluoroethylene lining, filling the polytetrafluoroethylene lining into a stainless steel crystallization kettle, performing dynamic hydrothermal crystallization in a homogeneous reactor at 175 ℃ at a rotating speed of 15r/min for 24 hours, performing suction filtration and deionized water washing on the obtained product to neutrality, and drying at 120 ℃ for 24 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 5, and the obtained product is the KL molecular sieve.

Example 4

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 23.42g KOH was weighed out and dissolved in a small amount of water, then added4.50gAl(OH)₃Heating to 100 ℃ in a three-neck flask, stirring and refluxing for 2h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 74.03g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at room temperature for 20 hours to obtain KL molecular sieve initial synthetic sol, in which the molar ratio of each material was 6.0K₂O：12.5SiO₂：1.0Al₂O₃：292.65H₂And O. And transferring the initial synthetic sol to a 200mL polytetrafluoroethylene lining, filling the polytetrafluoroethylene lining into a stainless steel crystallization kettle, performing dynamic hydrothermal crystallization in a homogeneous reactor at 175 ℃ at a rotating speed of 15r/min for 24 hours, performing suction filtration and deionized water washing on the obtained product to neutrality, and drying at 120 ℃ for 24 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 6, and the obtained product is the KL molecular sieve.

Example 5

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 23.42g KOH were weighed out and dissolved in a small amount of water, then 4.50g Al (OH) were added₃Heated to 100 ℃ in a three-necked flask, refluxed with stirring for 2.0h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 103.64g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at room temperature for 20 hours to obtain KL molecular sieve initial synthetic sol, in which the molar ratio of each material was 6.0K₂O：17.5SiO₂：1.0Al₂O₃：292.65H₂And O. And transferring the initial synthetic sol to a 200mL polytetrafluoroethylene lining, filling the polytetrafluoroethylene lining into a stainless steel crystallization kettle, performing dynamic hydrothermal crystallization in a homogeneous reactor at 175 ℃ at a rotating speed of 15r/min for 24 hours, performing suction filtration and deionized water washing on the obtained product to neutrality, and drying at 120 ℃ for 24 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 7, and the obtained product is the KL molecular sieve.

Example 6

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 23.42g KOH were weighed out and dissolved in a small amount of water, then 4.50g Al (OH) were added₃Heated to 120 ℃ in a three-necked flask, refluxed with stirring for 1.0h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 88.84g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at 60 ℃ for 10 hours, to obtain KL molecular sieve initial synthetic sol, in which the molar ratio of each material was 6.0K₂O：15.0SiO₂：1.0Al₂O₃：250H₂And O. And transferring the initial synthetic sol to a 200mL polytetrafluoroethylene lining, filling the polytetrafluoroethylene lining into a stainless steel crystallization kettle, performing dynamic hydrothermal crystallization in a homogeneous reactor at the rotating speed of 20r/min and the temperature of 160 ℃ for 48 hours, centrifuging the obtained product, washing the product with deionized water to be neutral, and drying the product at the temperature of 150 ℃ for 18 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 8, and the obtained product is the KL molecular sieve. FIG. 9 is an SEM image of the obtained sample, and the result shows that the size of the obtained KL molecular sieve is about 500 nm.

Example 7

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 23.42g KOH were weighed out and dissolved in a small amount of water, then 4.50g Al (OH) were added₃Heating to 80 ℃ in a three-neck flask, stirring and refluxing for 15h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 88.84g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at 40 ℃ for 16h to obtain KL molecular sieve initial synthetic sol, the molar ratio of each material in the initial synthetic sol was 6.0K₂O：15.0SiO₂：1.0Al₂O₃：200H₂And O. Transferring the initial synthetic sol to 200mL polytetrafluoroethylene lining, placing the lining into a stainless steel crystallization kettle, and placing the stainless steel crystallization kettle in a homogeneous reactorDynamic hydrothermal crystallization is carried out for 16h at 180 ℃ at the rotating speed of 15r/min, and the obtained product is centrifuged, washed by deionized water to be neutral and dried for 12h at 180 ℃ to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 10, and the obtained product is the KL molecular sieve.

Example 8

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 190.86g KOH were weighed out and dissolved in a small amount of water, then 40g Al (OH) were added₃Heating to 100 ℃ in a three-neck flask, stirring and refluxing for 2h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 789.65g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at room temperature for 8 hours to obtain KL molecular sieve initial synthetic sol, the molar ratio of each material in the initial synthetic sol was 5.5K₂O：15.0SiO₂：1.0Al₂O₃：292.65H₂And O. And transferring the initial synthetic sol to a 2L stainless steel crystallization kettle, performing dynamic hydrothermal crystallization at 175 ℃ for 24 hours at the rotating speed of 300r/min, filtering the obtained product, washing the product with deionized water to be neutral, and drying the product at 120 ℃ for 24 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 11, and the obtained product is the KL molecular sieve. This shows that KL molecular sieve can be obtained after the synthesis of example 5 by vertical scale-up.

Example 9

A method for dynamically synthesizing a KL molecular sieve without a structure directing agent comprises the following steps: 190.86g KOH were weighed out and dissolved in a small amount of water, then 40g Al (OH) were added₃Heating to 100 ℃ in a three-neck flask, stirring and refluxing for 2h, Al (OH)₃Completely dissolving, and clarifying the solution; after the solution was cooled to room temperature, the solution was transferred to a beaker, the remaining water was added and stirred well, and then 789.65g of silica Sol (SiO) was weighed₂Content of 30 wt.%) was slowly added to the above solution, and stirred and aged at room temperature for 16h to obtain KL molecular sieve initial synthesis solThe molar ratio of the materials in the initial synthetic sol is 5.5K₂O：15.0SiO₂：1.0Al₂O₃：292.65H₂And O. And transferring the initial synthetic sol to a 2L stainless steel crystallization kettle, performing dynamic hydrothermal crystallization at 175 ℃ for 24 hours at the rotating speed of 200r/min, filtering the obtained product, washing the product with deionized water to be neutral, and drying the product at 120 ℃ for 24 hours to obtain the KL molecular sieve raw powder.

And (3) taking a proper amount of sample for X-ray diffraction characterization, wherein the result is shown in figure 12, and the obtained product is the KL molecular sieve.

The above embodiments are only some of the embodiments of the present invention, and the embodiments are not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present invention are covered by the scope of the present invention claimed in the claims.