Method for synthesizing alpo-sfo molecular sieve with inert gas high pressure auxiliary and application thereof

Abstract

The application discloses a method for synthesizing AlPO-SFO molecular sieve with inert gas high pressure assistance and application, and comprises the following steps: mixing water, an aluminum source, a phosphorus source, hydrofluoric acid and a template agent 4-dimethylaminopyridine to form a reaction system; the reaction system is added into a high-pressure reaction kettle, inert gas is introduced after sealing, the reaction system is further increased to 1.8-4 MPa on the basis of autogenous pressure, and hydrothermal crystallization reaction is carried out at 100-175 DEG C for 6-24 h; after the reaction is completed, solid-liquid separation, washing, drying and calcination are carried out, and SFO topological structure aluminum phosphate molecular sieve is obtained. Through the inert gas high pressure assistance hydrothermal crystallization process, the formation of crystal nucleus and the growth of crystals are strengthened, the crystallization time of the AlPO-SFO molecular sieve is shortened from 72-96 h of the traditional hydrothermal method to 6-24 h, and the preparation efficiency is remarkably improved. The obtained AlPO-SFO molecular sieve still has good water vapor adsorption performance, low-temperature desorption regeneration performance and cycle stability, and can be used in the fields of gas dehumidification, air conditioning and liquid air energy storage air pretreatment.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve synthesis technology, and in particular to a method and application of high-pressure inert gas-assisted synthesis of AlPO-SFO molecular sieves. Background Technology

[0002] AlPO-SFO molecular sieves, as a novel microporous adsorbent material, possess high water vapor adsorption capacity and good thermal stability, showing promising application prospects in gas adsorption separation and air conditioning. In recent years, with the development of gas separation and liquid air energy storage, AlPO-SFO molecular sieves have received widespread attention in the field of gas dehumidification. Meanwhile, existing research has shown that AlPO-SFO molecular sieves have low desorption temperatures and can be regenerated at relatively low temperatures, thus possessing potential application value in low-grade waste heat utilization and low-energy-consumption adsorption regeneration.

[0003] Currently, AlPO-SFO molecular sieves are typically synthesized using the traditional hydrothermal method. Existing research indicates that this method generally requires a long crystallization period, typically 72–96 hours, resulting in a lengthy preparation cycle and low material preparation efficiency. Furthermore, the prolonged crystallization time not only increases energy consumption but also hinders large-scale preparation and industrial application of the material.

[0004] Furthermore, in traditional hydrothermal crystallization processes, the formation of crystal nuclei and the growth rate of crystals within the system are relatively slow, which can easily lead to insufficient crystallization efficiency and further prolong the reaction time. For AlPO-SFO molecular sieves, the crystallization process is quite sensitive to reaction conditions, and it is difficult to achieve rapid and stable crystallization in a short time under traditional conditions.

[0005] On the other hand, for adsorbent materials, in addition to the adsorption capacity of the material itself, their dynamic adsorption performance and cycle stability are equally important. Especially in continuous gas processing, adsorbents not only need to have a high adsorption capacity, but also a fast adsorption rate, stable cycle performance, and a low regeneration temperature.

[0006] Therefore, how to further shorten the crystallization time and improve the material preparation efficiency while ensuring the adsorption performance and low-temperature regeneration performance of the AlPO-SFO molecular sieve, and at the same time maintain good dynamic adsorption performance and cycle stability, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the problems of long crystallization time, low preparation efficiency, and difficulty in rapid and stable crystallization of existing AlPO-SFO molecular sieves, this invention provides a method for the high-pressure-assisted synthesis of AlPO-SFO molecular sieves using inert gas and its application. This method introduces an inert gas during the hydrothermal crystallization process, further pressurizing the reaction system beyond its self-generated pressure. This increases the crystallization driving force, promotes crystal nucleus formation and crystal growth, achieving rapid crystallization of AlPO-SFO molecular sieves while maintaining their water vapor adsorption and low-temperature regeneration properties.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for high-pressure-assisted synthesis of AlPO-SFO molecular sieves using inert gas includes the following steps:

[0010] Step 1, Mixing: Water, aluminum source, phosphorus source, hydrofluoric acid and template agent 4-dimethylaminopyridine are mixed to form a reaction system. No seed crystals are added to the reaction system.

[0011] Step 2, hydrothermal reaction: The reaction system is added to a high-pressure reactor, sealed, and inert gas is introduced to further increase the pressure of the reaction system to 1.8-4 MPa based on its own pressure, and a hydrothermal crystallization reaction is carried out at 100-175 °C for 6-24 h.

[0012] Step 3, Separation: After the reaction is complete, solid-liquid separation is performed, and the resulting solid product is washed.

[0013] Step 4, calcination: The washed product is dried and calcined to obtain AlPO-SFO molecular sieve; wherein the calcination temperature is 550-600 ℃ and the calcination time is 4-8 h.

[0014] Further, in step 1, the aluminum source is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum phosphate, and aluminum chloride; the phosphorus source is selected from at least one of orthophosphoric acid, phosphorous acid, ammonium dihydrogen phosphate, phosphorus oxide, and aluminum phosphate.

[0015] Further, in step 1, the molar ratio of each component in the reaction system is:

[0016] 4-DMAPy: Al2O3: P2O5: H2O: HF = 1.5~2.5: 1: 1: 30~50: 0.3~0.7.

[0017] Furthermore, in step 2, the inert gas is one or more of nitrogen, argon, or helium.

[0018] Furthermore, in step 2, the hydrothermal crystallization reaction time is preferably about 24 hours.

[0019] Furthermore, the prepared AlPO-SFO molecular sieve exhibits a water vapor adsorption capacity of 13–16 mmol / g at 25 °C.

[0020] Furthermore, the prepared AlPO-SFO molecular sieve retained more than 90% of its adsorption capacity after multiple water vapor adsorption cycles.

[0021] An AlPO-SFO molecular sieve prepared using the above method.

[0022] The present invention also provides an application of the above-mentioned AlPO-SFO molecular sieve in gas dehumidification, air conditioning or liquid air energy storage air pretreatment.

[0023] By adopting the above technical solution: after using inert gas high-pressure assisted hydrothermal reaction, the crystallization time of AlPO-SFO molecular sieve is shortened from 72-96 h in the traditional hydrothermal method to 6-24 h; the prepared AlPO-SFO molecular sieve has a high water vapor adsorption capacity, a fast dynamic adsorption rate and good cycle stability; the prepared AlPO-SFO molecular sieve has a low regeneration temperature, and water desorption and regeneration can be achieved under low temperature conditions.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention increases the pressure of the hydrothermal system by introducing an inert gas, thereby strengthening the crystal nucleation and crystal growth process. This reduces the crystallization time of AlPO-SFO molecular sieve from the traditional 72-96 h to approximately 6-24 h, significantly improving the material preparation efficiency.

[0026] 2. The inert gas high-pressure assisted method used in this invention can effectively improve the crystallization efficiency of the system, shorten the preparation cycle, and reduce the preparation energy consumption, and has good prospects for industrial application.

[0027] 3. The AlPO-SFO molecular sieve prepared by this invention maintains high water vapor adsorption performance and good cycle stability while shortening the crystallization time. Attached Figure Description

[0028] Figure 1 The XRD patterns of AlPO-SFO molecular sieves synthesized by the conventional hydrothermal method and AlPO-SFO molecular sieves synthesized in Examples 1-3 are shown.

[0029] Figure 2 The above are the water vapor isothermal adsorption curves of the AlPO-SFO molecular sieves synthesized in Examples 1-3 at 25 °C.

[0030] Figure 3 The graph shows the adsorption-desorption cycle curves of 10 water vapor cycles of the AlPO-SFO molecular sieve synthesized in Example 1 at a desorption temperature of 65 °C. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment provides a method for high-pressure-assisted synthesis of AlPO-SFO molecular sieves using inert gas, comprising the following steps:

[0034] Step 1, Mixing: Water, aluminum source, phosphorus source, hydrofluoric acid, and template agent 4-dimethylaminopyridine are mixed to form a homogeneous reaction system. No seed crystals are added to this reaction system. The molar ratio of each component in the reaction system is as follows:

[0035] 4-DMAPy: Al2O3: P2O5: H2O: HF = 2: 1: 1: 40: 0.5.

[0036] Step 2, hydrothermal reaction: The above reaction system was added to a high-pressure reactor, sealed, and inert gas was introduced to further increase the pressure of the reaction system to 4 MPa based on its autogenous pressure. Subsequently, the high-pressure reactor was heated to 175 °C, and a hydrothermal crystallization reaction was carried out under this temperature and pressure conditions for 24 h.

[0037] Step 3, Separation: After the reaction is complete, the high-pressure reactor is allowed to cool naturally to room temperature. The reaction product is then removed, and solid-liquid separation is performed on the resulting product. The separated solid product is washed with deionized water to remove residual impurities.

[0038] Step 4, calcination: The washed solid product is dried and then calcined at 550-600 °C for 6 h to remove the template agent, thus obtaining AlPO-SFO molecular sieve.

[0039] In this embodiment, an inert gas is introduced into the high-pressure reactor to further increase the pressure of the reaction system based on its own pressure. Compared with the traditional hydrothermal method, this method can enhance the crystal nucleation and crystal growth process, shortening the crystallization time of AlPO-SFO molecular sieve from 72-96 h in the traditional method to 6-24 h, preferably to about 24 h.

[0040] Example 2

[0041] Weigh out aluminum source, phosphorus source, hydrofluoric acid, template agent 4-dimethylaminopyridine, and deionized water, and mix them in the same proportion as in Example 1 to form a homogeneous reaction system.

[0042] The reaction system was then added to a high-pressure reactor, sealed, and inert gas was introduced to raise the pressure of the reaction system to 3 MPa. The hydrothermal crystallization reaction was then carried out at 170–180 °C for 24 h.

[0043] After the reaction was completed, the resulting product was subjected to solid-liquid separation and washed with deionized water. The sample was then dried at 100 °C for 12 h and calcined at 550–600 °C for 6 h to obtain the AlPO-SFO molecular sieve sample.

[0044] Example 3

[0045] Weigh out aluminum source, phosphorus source, hydrofluoric acid, template agent 4-dimethylaminopyridine, and deionized water, and mix them in the same proportion as in Example 1 to form a homogeneous reaction system.

[0046] The reaction system was then added to a high-pressure reactor, sealed, and inert gas was introduced to raise the pressure of the reaction system to 2 MPa. The hydrothermal crystallization reaction was then carried out at 170–180 °C for 24 h.

[0047] After the reaction was completed, the resulting product was subjected to solid-liquid separation and washed with deionized water. The sample was then dried at 100 °C for 12 h and calcined at 550–600 °C for 6 h to obtain the AlPO-SFO molecular sieve sample.

[0048] Structural characterization

[0049] X-ray diffraction tests were performed on the AlPO-SFO molecular sieves prepared in Examples 1-3 and the AlPO-SFO molecular sieves prepared by the conventional hydrothermal method. The results are as follows: Figure 1 As shown.

[0050] Depend on Figure 1It can be seen that the AlPO-SFO molecular sieve prepared by this invention and the AlPO-SFO molecular sieve prepared by conventional methods have similar characteristic diffraction peaks, indicating that the AlPO-SFO molecular sieve prepared by the inert gas high-pressure assisted hydrothermal method of this invention can be successfully prepared. Furthermore, under the condition of significantly shortened crystallization time, the sample obtained by the method of this invention can still form a crystal phase structure consistent with that of the conventional method, indicating that the inert gas high-pressure assisted condition does not destroy the crystal structure of the AlPO-SFO molecular sieve.

[0051] The test results show that the method of the present invention can achieve effective crystallization of AlPO-SFO molecular sieves in a short time, solving the problems of long crystallization time and low preparation efficiency of traditional hydrothermal methods.

[0052] Water vapor adsorption performance test

[0053] To verify the water vapor adsorption performance of the AlPO-SFO molecular sieve obtained in this invention, water vapor adsorption tests were conducted on the samples prepared in Examples 1-3 at 25 °C. The results are as follows: Figure 2 As shown.

[0054] Depend on Figure 2 It can be seen that the water vapor adsorption capacity of the AlPO-SFO molecular sieve prepared in this invention gradually increases with the increase of relative pressure P / P0. When P / P0 increases from 0 to 0.2, the adsorption capacity rapidly increases to 12.224 mmol / g, indicating that the material has a fast water vapor adsorption response in the low relative pressure range. As the relative pressure continues to increase, the adsorption capacity further increases, and when P / P0 reaches 0.95, the maximum water vapor adsorption capacity of the sample reaches 15.199 mmol / g.

[0055] The results show that after shortening the crystallization time using the inert gas high-pressure assisted hydrothermal method of the present invention, the obtained AlPO-SFO molecular sieve still has a high water vapor adsorption capacity and good adsorption performance, and can be used in fields such as gas dehumidification and air conditioning.

[0056] Low-temperature desorption cycle stability test

[0057] To investigate the cycling stability of the AlPO-SFO molecular sieve obtained in this invention under low-temperature desorption conditions, the sample prepared in Example 1 was subjected to 10 water vapor adsorption-desorption cycles, with the desorption temperature being 65 °C. The results are as follows: Figure 3 As shown.

[0058] Depend on Figure 3It can be seen that the AlPO-SFO molecular sieve prepared in this invention can maintain a high water vapor adsorption capacity during 10 adsorption-desorption cycles. The adsorption capacity in the first cycle was 14.996 mmol / g, and the adsorption capacity after the 10th cycle was still 14.012 mmol / g, with a capacity retention rate of approximately 93.4%. This indicates that the material can be effectively regenerated under low-temperature desorption conditions of 65 ℃, and the adsorption capacity did not show significant decay during the cycle.

[0059] The results showed that AlPO-SFO molecular sieves could be formed under conditions of 2 MPa, 3 MPa, and 4 MPa, but the crystallinity of the samples gradually increased with increasing pressure. The sample obtained under 4 MPa showed better crystallinity and higher water vapor adsorption capacity. This indicates that appropriately increasing the system pressure is beneficial to promoting crystal nucleation and crystal growth, thereby improving crystallization efficiency.

[0060] Comparison and explanation

[0061] Traditional AlPO-SFO molecular sieves are typically synthesized using conventional hydrothermal methods, with a crystallization time generally ranging from 72 to 96 hours. Compared to traditional methods, this invention introduces an inert gas to increase the pressure of the hydrothermal reaction system, further increasing the pressure on top of the self-generated pressure. This accelerates the formation of crystal nuclei and the crystal growth process, shortening the crystallization time to 6–24 hours, preferably approximately 24 hours.

[0062] At the same time, by Figures 1 to 3 As can be seen, while shortening the crystallization time, the AlPO-SFO molecular sieve obtained by this invention still possesses a well-defined crystalline phase structure, good water vapor adsorption performance, low-temperature desorption capacity, and good cycling stability. Therefore, this invention not only improves the preparation efficiency of AlPO-SFO molecular sieves but also ensures their application performance as water vapor adsorption materials.

[0063] In summary, the AlPO-SFO molecular sieve prepared by this invention can be used in fields such as gas dehumidification, air conditioning, and air pretreatment for liquid air energy storage. Especially in gas treatment processes requiring repeated adsorption and regeneration of the adsorbent, the material obtained by this invention has advantages such as short crystallization time, good adsorption performance, good low-temperature regeneration capability, and good cycle stability, showing promising prospects for engineering applications.

[0064] The descriptions and practices disclosed in this invention are readily apparent and understandable to those skilled in the art, and various modifications and refinements can be made without departing from the principles of this invention. Therefore, any modifications or improvements made without departing from the spirit of this invention should also be considered within the scope of protection of this invention.

Claims

1. A method for high-pressure-assisted synthesis of AlPO-SFO molecular sieves using inert gas, characterized in that, Includes the following steps: Step 1, Mixing: Mix water, aluminum source, phosphorus source, hydrofluoric acid and template agent 4-dimethylaminopyridine to form a reaction system; Step 2, hydrothermal reaction: The reaction system is added to a high-pressure reactor, sealed, and inert gas is introduced to further increase the pressure of the reaction system to 1.8-4 MPa based on its own pressure, and a hydrothermal crystallization reaction is carried out at 100-175 °C for 6-24 h. Step 3, Separation: After the reaction is complete, solid-liquid separation is performed, and the resulting solid product is washed. Step 4, calcination: The washed product is dried and calcined to obtain AlPO-SFO molecular sieve; wherein the calcination temperature is 550-600 ℃ and the calcination time is 4-8 h.

2. The method for high-pressure inert gas-assisted synthesis of AlPO-SFO molecular sieves according to claim 1, characterized in that: In step 1, the aluminum source is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum phosphate, and aluminum chloride; The phosphorus source is selected from at least one of orthophosphoric acid, phosphorous acid, ammonium dihydrogen phosphate, phosphorus oxides, and aluminum phosphate.

3. The method for high-pressure inert gas-assisted synthesis of AlPO-SFO molecular sieves according to claim 1, characterized in that: In step 1, the molar ratio of each component in the reaction system is: 4-DMAPy: Al2O3: P2O5: H2O: HF = 1.5~2.5: 1: 1: 30~50: 0.3~0.

7.

4. The method for high-pressure inert gas-assisted synthesis of AlPO-SFO molecular sieves according to claim 1, characterized in that, In step 2, the inert gas is one or more of nitrogen, argon, or helium.

5. A method for high-pressure inert gas-assisted synthesis of AlPO-SFO molecular sieves according to any one of claims 1 to 4, characterized in that, The prepared AlPO-SFO molecular sieve has a water vapor adsorption capacity of 13–16 mmol / g at 25 °C.

6. A method for high-pressure inert gas-assisted synthesis of AlPO-SFO molecular sieves according to any one of claims 1 to 4, characterized in that, The prepared AlPO-SFO molecular sieve retained more than 90% of its adsorption capacity after multiple water vapor adsorption cycles.

7. An AlPO-SFO molecular sieve prepared by the method described in any one of claims 1 to 6.

8. The application of the AlPO-SFO molecular sieve according to claim 7 in gas dehumidification.

9. The application of the AlPO-SFO molecular sieve according to claim 7 in air conditioning.

10. The application of the AlPO-SFO molecular sieve according to claim 7 in air pretreatment for liquid air energy storage.

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