Preparation method of modified SSZ-13 molecular sieve
Through microwave heating combined with conventional heating, the SSZ-13 molecular sieve is modified by sodium metaaluminate, ammonia water and potassium hydroxide, and the problem of rapid synthesis of high crystallinity and large crystal molecular sieve is solved, and its adsorption performance of paraxylene is improved, and cost savings and performance improvements are achieved.
Patent Information
- Application Number
- CN202510630929.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-16
- Publication Date
- 2025-08-26
AI Technical Summary
The prior art is difficult to quickly synthesize high crystallinity and large crystalline SSZ-13 molecular sieves with high crystallinity and large grains under the premise of cost saving, and its adsorption performance on volatile organic matter is limited.
Microwave heating combined with conventional two-stage heating method, the SSZ-13 molecular sieve was treated by composite modification of sodium metaaluminate, ammonia water and potassium hydroxide, combined with microwave radiation and calcination steps to achieve rapid nucleation and stable crystal growth, and a modified SSZ-13 molecular sieve with high crystallinity and large grains were prepared.
While reducing production costs, the adsorption rate and adsorption capacity of molecular sieve to typical VOCs xylene is improved, and the adsorption performance of molecular sieve is improved.
Abstract
Description
Technical Field
[0001] The present invention relates to the field of chemical preparation, and in particular to a preparation method of a modified SSZ-13 molecular sieve. Background Art
[0002] VOCs, volatile organic compounds (VOCs), are naturally harmful to humans and animals. Their hazards lie not only in their photochemical reactions with nitrogen oxides under strong sunlight, contributing to the increasing severity of fine particle pollution such as PM2.5 and becoming the "culprit" of smog, but more importantly, they affect people's lives and threaten their health. Therefore, strict VOC control is imperative, and end-of-pipe control measures are essential for the treatment of VOC waste gas pollution from industrial sources. Adsorption is an effective method for VOC control, and efficient adsorbents are the key to adsorption.
[0003] Molecular sieves, microporous silicate or aluminosilicate crystals, are formed by oxygen bridges between silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra, creating a uniform internal cavity system. They rely on physical adsorption to attract molecules smaller than their diameter into the cavity system, achieving a screening effect. Due to their large specific surface area, well-developed microporous structure, high silicon-to-aluminum ratio, and excellent hydrothermal stability, they exhibit excellent adsorption properties for various VOCs under dry conditions, making them a key component of adsorption methods. Summary of the Invention
[0004] The object of the present invention is to provide a method for preparing a modified SSZ-13 molecular sieve, which can save production costs and achieve rapid nucleation and stable crystal growth, thereby obtaining a molecular sieve product with high crystallinity and large grains, and has varying degrees of improvement in the adsorption rate and adsorption capacity of the typical VOCs xylene on the molecular sieve.
[0005] Microwave heating is a process in which polar molecules in a material are polarized under the action of an external alternating electromagnetic field. As the polarity of the field changes, they frequently turn to friction, converting electromagnetic energy into heat energy. This process has the characteristics of fast and uniform heating rates, high energy efficiency, and environmental friendliness. It is particularly effective in influencing reaction kinetics and selectivity in the synthesis of nanoporous materials. Microwaves can be used to synthesize new nanoporous materials, shortening synthesis time and reducing energy consumption. The shortened synthesis time makes it possible to achieve continuous production, replacing the current intermittent production.
[0006] Microwaves show good reaction selectivity in the process of synthesizing molecular sieves. The crystals obtained are basically free of impurities and have small grain size. As a heating method, microwaves are more intense than conventional convection heat transfer. The violent vibration of polar material molecules in the early stage of the reaction is more conducive to the activation and decomposition of raw materials, thereby quickly forming a large number of crystal nuclei. The reaction quickly enters the crystal growth stage, which is why crystal formation can be detected within a very short reaction time. However, due to the intense heating form, it also affects the stable growth of crystals. After the reaction reaches a certain extent, the crystal growth and crystal structure collapse, forming a dynamic equilibrium, resulting in small product crystal particle size and low crystallinity. Even if the reaction time is extended, there will be no significant improvement. Microwaves are used in combination with conventional two-stage heating to achieve the purpose of rapid nucleation and stable crystal growth. While achieving rapid synthesis, molecular sieve products with high crystallinity and large grains can be obtained.
[0007] The technical solution adopted by the present invention to solve the above problems is:
[0008] A method for preparing a modified SSZ-13 molecular sieve comprises the following steps:
[0009] Step A, calcining SSZ-13 molecular sieve powder at 200°C for 6 hours and then placing it in a desiccator and cooling it to room temperature;
[0010] Step B, dissolving three different concentrations of sodium metaaluminate, ammonia water, and potassium hydroxide in a beaker, and stirring until clear;
[0011] Step C, weighing the calcined SSZ-13 molecular sieve raw powder using an analytical balance;
[0012] Step D, adding the weighed SSZ-13 molecular sieve raw powder, stirring for 10 hours and then performing microwave heating;
[0013] Step E: finally, the obtained precursor is placed in a reactor and crystallized by programmed temperature heating;
[0014] Step F: After the crystallization is completed, microwave treatment is performed, and the product is cooled to room temperature, filtered, washed with water until neutral, and then microwave treatment is continued and calcined to obtain a modified SSZ-13 molecular sieve.
[0015] Furthermore, the method comprises the following steps: calcining the SSZ-13 molecular sieve powder at 200° C. for 6 hours and then placing it in a desiccator to cool to room temperature; weighing a certain amount of the calcined molecular sieve using an analytical balance and adding it to a stirred clarified solution, and continuing to stir for 6 hours; after the 6-hour stirring is completed, hydrogen exchange is performed under microwave irradiation for 30 minutes to 12 hours, with a microwave power of 100 to 800 W; cooling to room temperature in air, filtering, washing with water until neutral, and drying under microwave irradiation for 20 minutes to 3 hours, with a microwave power of 100 to 800 W; and calcining in a muffle furnace at 500 to 800° C. for 24 to 48 hours to obtain a modified SSZ-13 molecular sieve.
[0016] Furthermore, in step D, the microwave radiation power is 0-1500W, the microwave frequency is 2450MHz, the treatment temperature is 20-250°C, and the treatment time is 10min-48h.
[0017] Furthermore, the programmed temperature heating methods in step E are: 20-50°C, stay for 10 min to 2 h; 50-90°C, stay for 10 min to 2 h; 90-130°C, stay for 10 min to 2 h; 130-170°C, stay for 10 min to 2 h; 170-210°C, stay for 10 min to 2 h; 210-250°C, stay for 10 min to 2 h.
[0018] Furthermore, in step A, the drying temperature is 100-200° C., and the drying time is 4-48 hours.
[0019] Furthermore, the ammonium solution is one or more of ammonium phosphate, ammonium monohydrogen phosphate, and ammonium dihydrogen phosphate.
[0020] Furthermore, the sodium metaaluminate, ammonia water and potassium hydroxide are 0.1-0.5 mol / L, 0.6-0.8 mol / L and 1.5-2 mol / L respectively.
[0021] Furthermore, it also includes changing the acidity to determine the optimal modified molecular sieve concentration under the condition that other conditions remain unchanged, and conducting static water absorption and VOCs tests on the modified SSZ-13 molecular sieve.
[0022] Compared with the prior art, the present invention has the following advantages and effects:
[0023] The present invention uses three reagents (sodium metaaluminate, ammonia water and potassium hydroxide) to compositely modify the SSZ-13 molecular sieve. Compared with the unmodified molecular sieve, the present invention not only saves production costs, but also utilizes microwave heating and drying to achieve the purpose of rapid nucleation and stable crystal growth. While rapidly synthesizing, it also achieves the ability to obtain a molecular sieve product with high crystallinity and large grains, and improves the adsorption rate and adsorption capacity of the typical VOCs xylene on the molecular sieve to varying degrees. DETAILED DESCRIPTION
[0024] The present invention will be further described in detail below by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.
[0025] Example 1:
[0026] The present embodiment provides a method for preparing a modified SSZ-13 molecular sieve, comprising the following steps:
[0027] Step A: Weigh the SSZ-13 molecular sieve raw powder and calcine it in a calciner at 200°C for 6 hours. After calcination, place it in a desiccator and cool it to room temperature.
[0028] Step B: dissolve 2 mol / L sodium metaaluminate, ammonia water, and potassium hydroxide in deionized water and stir until the solution is clear.
[0029] Step C, then weighing a certain amount of calcined SSZ-13 molecular sieve into the above clear solution, stirring for 6 hours, and then heating in a microwave at 700W and 100°C for 2 hours;
[0030] Step D: The obtained precursor was placed in a reactor and heated to 50°C for 30 min; 100°C for 30 min; 150°C for 30 min; 200°C for 1 h; 250°C for 2 h;
[0031] Step E: After the crystallization is completed, the mixture is cooled to room temperature, filtered, washed with water until neutral, and dried at 200°C for 6 hours;
[0032] Step F, followed by microwave irradiation at a microwave power of 300 W, hydrogen exchange for 40 min, cooling to room temperature in air, filtration, washing with water until neutral, continuing microwave irradiation at a microwave power of 350 W, drying for 20 min, and calcining in a muffle furnace at 550° C. for 24 h to obtain a modified SSZ-13 molecular sieve, recorded as (2 mol / lSSZ-13);
[0033] In step G, 3 portions of original SSZ-13 molecular sieve and modified SSZ-13 molecular sieve calcined at 200°C for 6 hours were weighed and 0.3500 g (±0.1 g) were respectively placed in a low-temperature thermostat preheated at 36°C for 4 hours for static water absorption and xylene test. After 4 hours of adsorption, the weights were weighed and the adsorption amount was calculated.
[0034] Example 2:
[0035] Step A: Weigh the SSZ-13 molecular sieve raw powder and calcine it in a calciner at 200°C for 6 hours. After calcination, place it in a desiccator and cool it to room temperature.
[0036] Step B: dissolve 1 mol / L sodium metaaluminate, ammonia water, and potassium hydroxide in deionized water and stir until the solution is clear.
[0037] Step C, then weighing a certain amount of calcined SSZ-13 molecular sieve into the above clear solution, stirring for 6 hours, and then heating in a microwave at 700W and 100°C for 2 hours;
[0038] Step D: The obtained precursor was placed in a reactor and heated to 50°C for 30 min; 100°C for 30 min; 150°C for 30 min; 200°C for 1 h; 250°C for 2 h;
[0039] Step E: After the crystallization is completed, the mixture is cooled to room temperature, filtered, washed with water until neutral, and dried at 200°C for 6 hours;
[0040] Step F, followed by microwave irradiation at a microwave power of 300 W, hydrogen exchange for 40 min, cooling to room temperature in air, filtration, washing with water until neutral, continuing microwave irradiation at a microwave power of 350 W, drying for 20 min, and calcining in a muffle furnace at 550° C. for 24 h to obtain a modified SSZ-13 molecular sieve, recorded as (1 mol / lSSZ-13);
[0041] In step G, 3 portions of original SSZ-13 molecular sieve and modified SSZ-13 molecular sieve calcined at 200°C for 6 hours were weighed and 0.3500 g (±0.1 g) were respectively placed in a low-temperature thermostat preheated at 36°C for 4 hours for static water absorption and xylene test. After 4 hours of adsorption, the weights were weighed and the adsorption amount was calculated.
[0042] Example 3:
[0043] Step A: Weigh the SSZ-13 molecular sieve raw powder and calcine it in a calciner at 200°C for 6 hours. After calcination, place it in a desiccator and cool it to room temperature.
[0044] Step B: dissolve 1.5 mol / L sodium metaaluminate, ammonia water, and potassium hydroxide in deionized water and stir until the solution is clear.
[0045] Step C, then weighing a certain amount of calcined SSZ-13 molecular sieve into the above clear solution, stirring for 6 hours, and then heating in a microwave at 700W and 100°C for 2 hours;
[0046] Step D: The obtained precursor was placed in a reactor and heated to 50°C for 30 min; 100°C for 30 min; 150°C for 30 min; 200°C for 1 h; 250°C for 2 h;
[0047] Step E: After the crystallization is completed, the mixture is cooled to room temperature, filtered, washed with water until neutral, and dried at 200°C for 6 hours;
[0048] Step F, followed by microwave irradiation at a microwave power of 300 W, hydrogen exchange for 40 min, cooling to room temperature in air, filtration, washing with water until neutral, continuing microwave irradiation at a microwave power of 350 W, drying for 20 min, and calcining in a muffle furnace at 550° C. for 24 h to obtain a modified SSZ-13 molecular sieve, recorded as (1.5 mol / lSSZ-13);
[0049] In step G, 3 portions of original SSZ-13 molecular sieve and modified SSZ-13 molecular sieve calcined at 200°C for 6 hours were weighed and 0.3500 g (±0.1 g) were respectively placed in a low-temperature thermostat preheated at 36°C for 4 hours for static water absorption and xylene test. After 4 hours of adsorption, the weights were weighed and the adsorption amount was calculated.
[0050] Example 4:
[0051] Step A: Weigh the SSZ-13 molecular sieve raw powder and calcine it in a calciner at 200°C for 6 hours. After calcination, place it in a desiccator and cool it to room temperature.
[0052] Step B: dissolve 1.2 mol / L sodium metaaluminate, ammonia water, and potassium hydroxide in deionized water and stir until the solution is clear.
[0053] Step C, then weighing a certain amount of calcined SSZ-13 molecular sieve into the above clear solution, stirring for 6 hours, and then heating in a microwave at 700W and 100°C for 2 hours;
[0054] Step D: The obtained precursor was placed in a reactor and heated to 50°C for 30 min; 100°C for 30 min; 150°C for 30 min; 200°C for 1 h; 250°C for 2 h;
[0055] Step E: After the crystallization is completed, the mixture is cooled to room temperature, filtered, washed with water until neutral, and dried at 200°C for 6 hours;
[0056] Step F, followed by microwave irradiation at a microwave power of 300 W, hydrogen exchange for 40 min, cooling to room temperature in air, filtration, washing with water until neutral, continuing microwave irradiation at a microwave power of 350 W, drying for 20 min, and calcining in a muffle furnace at 550° C. for 24 h to obtain a modified SSZ-13 molecular sieve, recorded as (1.2 mol / lSSZ-13);
[0057] In step G, 3 portions of original SSZ-13 molecular sieve and modified SSZ-13 molecular sieve calcined at 200°C for 6 hours were weighed and 0.3500 g (±0.1 g) were respectively placed in a low-temperature thermostat preheated at 36°C for 4 hours for static water absorption and xylene test. After 4 hours of adsorption, the weights were weighed and the adsorption amount was calculated.
[0058] In summary, the composite modification of SSZ-13 molecular sieve with three reagents (sodium aluminate, ammonia water and potassium hydroxide) not only saves production costs compared with the unmodified molecular sieve, but also uses microwave heating and drying to achieve the purpose of rapid nucleation and stable crystal growth. While rapidly synthesizing, it also achieves the goal of obtaining molecular sieve products with high crystallinity and large grains, and the adsorption rate and adsorption capacity of typical VOCs xylene on the molecular sieve are improved to varying degrees.
[0059] The above contents described in this specification are merely examples of the present invention. Those skilled in the art may make various modifications, additions, or substitutions to the described embodiments, without departing from the contents of this specification or exceeding the scope defined by the claims, and such modifications, additions, or substitutions may be made to the described embodiments. Such modifications, additions, or substitutions may be made by persons skilled in the art. Such modifications, additions, or substitutions may be made to the described embodiments without departing from the contents of this specification or exceeding the scope defined by the claims, and such modifications shall fall within the scope of protection of the present invention.
Claims
1. A method for preparing a modified SSZ-13 molecular sieve, characterized in that: The steps include: Step A, calcining SSZ-13 molecular sieve powder at 200°C for 6 hours and then placing it in a desiccator and cooling it to room temperature; Step B, dissolving three different concentrations of sodium metaaluminate, ammonia water, and potassium hydroxide in a beaker, and stirring until clear; Step C, weighing the calcined SSZ-13 molecular sieve raw powder using an analytical balance; Step D, adding the weighed SSZ-13 molecular sieve raw powder, stirring for 10 hours and then performing microwave heating; Step E: finally, the obtained precursor is placed in a reactor and crystallized by programmed temperature heating; Step F: After the crystallization is completed, microwave treatment is performed, and the product is cooled to room temperature, filtered, washed with water until neutral, and then microwave treatment is continued and calcined to obtain a modified SSZ-13 molecular sieve.
2. The method for preparing the modified SSZ-13 molecular sieve according to claim 1, wherein: The method further comprises the following steps: calcining SSZ-13 molecular sieve powder at 200° C. for 6 hours, placing the powder in a desiccator and cooling it to room temperature; weighing a certain amount of the calcined molecular sieve using an analytical balance and adding the mixture to a stirred clarified solution; and continuing to stir the mixture for 6 hours. After the 6-hour stirring is completed, hydrogen exchange is performed under microwave irradiation for 30 minutes to 12 hours at a microwave power of 100 to 800 W; cooling the mixture to room temperature in air, filtering the mixture, washing the mixture with water until the mixture is neutral, and drying the mixture under microwave irradiation for 20 minutes to 3 hours at a microwave power of 100 to 800 W; and calcining the mixture in a muffle furnace at 500 to 800° C. for 24 to 48 hours to obtain a modified SSZ-13 molecular sieve.
3. The method for preparing the modified SSZ-13 molecular sieve according to claim 1, wherein: In step D, the microwave radiation power is 0 to 1500 W, the microwave frequency is 2450 MHz, the treatment temperature is 20 to 250° C., and the treatment time is 10 min to 48 h.
4. The method for preparing the modified SSZ-13 molecular sieve according to claim 1, wherein: The programmed temperature heating methods in step E are: 20-50°C, stay for 10 minutes to 2 hours; 50-90°C, stay for 10 minutes to 2 hours; 90-130°C, stay for 10 minutes to 2 hours; 130-170°C, stay for 10 minutes to 2 hours; 170-210°C, stay for 10 minutes to 2 hours; 210-250°C, stay for 10 minutes to 2 hours.
5. The method for preparing the modified SSZ-13 molecular sieve according to claim 1, wherein: In step A, the drying temperature is 100-200° C., and the drying time is 4-48 hours.
6. The method for preparing the modified SSZ-13 molecular sieve according to claim 1, wherein: The ammonium solution is one or more of ammonium phosphate, ammonium monohydrogen phosphate, and ammonium dihydrogen phosphate.
7. The method for preparing the modified SSZ-13 molecular sieve according to claim 1, wherein: The sodium metaaluminate, ammonia water and potassium hydroxide are 0.1-0.5 mol / L, 0.6-0.8 mol / L and 1.5-2 mol / L respectively.
8. The method for preparing the modified SSZ-13 molecular sieve according to claim 1, wherein: It also includes changing the acidity to determine the optimal modified molecular sieve concentration when other conditions remain unchanged, and conducting static water absorption and VOCs tests on the modified SSZ-13 molecular sieve.