Salt solution modified molecular sieve, preparation method and application thereof
By modifying Na-type molecular sieves through cation exchange and infiltration, the loading capacity of metal inorganic salts on the molecular sieves was increased, solving the problem of low loading capacity of traditional molecular sieves and achieving higher heat storage density and better thermochemical heat storage performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF ENGINEERING THERMOPHYSICS - CHINESE ACAD OF SCI
- Filing Date
- 2023-12-25
- Publication Date
- 2026-06-26
AI Technical Summary
Traditional molecular sieves have low loading capacity for inorganic salt solutions, which limits their use in thermochemical thermal storage and makes them prone to leakage during hydration/desorption reactions.
Na-type molecular sieves are modified with specific metal inorganic salt solutions by cation replacement, sintering, and infiltration. The loading of metal inorganic salts on the molecular sieves is increased through replacement and infiltration, thus forming salt solution modified molecular sieves.
It significantly improves the loading capacity and reaction enthalpy of metal inorganic salts, solves the problem of low loading capacity of traditional molecular sieves, and avoids leakage during hydration/desorption reactions, thus significantly improving heat storage density and energy storage effect.
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Figure CN117800352B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical thermal storage technology, specifically to a salt solution modified molecular sieve, its preparation method, and its application. Background Technology
[0002] Compared to sensible and latent heat storage technologies, thermochemical thermal storage offers higher storage density and lower heat loss over long periods. Furthermore, the hydration / desorption reaction temperature of inorganic salts with water exhibits high compatibility with solar energy utilization, and it is pollution-free and low-cost. To address the shortcomings of pure hydrated salts in thermal storage applications, such as poor cycle stability and susceptibility to deliquescence and clumping, researchers both domestically and internationally have combined hydrated salts with porous materials to prepare composite materials. The principle is as follows: During the exothermic process, the porous material first undergoes physical adsorption, followed by a hydration reaction between the hydrated salt and water vapor within the pores. The resulting crystalline hydrate continues to adsorb water vapor, forming a hydrated salt solution that is stored in the porous substrate. During the thermal storage process, the opposite desorption process occurs. The preparation of composite inorganic salt thermochemical thermal storage materials using porous materials is currently a research hotspot.
[0003] Current research on porous matrix composite thermal storage materials mostly utilizes the skeletal function of porous structures and fills the interior of these pores with phase change materials. For example, similar methods are mentioned in Chinese patent application CN113717696A, which discloses a method for preparing a modified diatomite-based porous phase change material, and CN112883540A, which discloses a method for reconstructing a porous phase change material with specific pore structures and thermal properties.
[0004] Molecular sieves are aluminosilicate compounds with a uniform microporous structure, whose micropores can adsorb molecules smaller than their diameter into the pores. However, traditional molecular sieves have low loading capacity for inorganic salt solutions, and often suffer from leakage problems during hydration / desorption reactions, which greatly limits their application in thermochemical thermal storage. Summary of the Invention
[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the traditional molecular sieves in the prior art have low loading capacity for inorganic salt solutions, which limits their use in thermochemical heat storage, and thus provide a salt solution modified molecular sieve, its preparation method and application to solve the above problems.
[0006] A method for preparing salt solution modified molecular sieves, comprising:
[0007] Cation exchange: The Na-type molecular sieve is replaced by a solution of the first metal inorganic salt by allowing it to stand for a period of time.
[0008] Sintering: The replaced molecular sieve is calcined at a temperature above 400℃;
[0009] Impregnation: The sintered molecular sieve is mixed with a second metal inorganic salt solution for impregnation;
[0010] Separation and drying: After impregnation, separation and drying are carried out to obtain salt solution modified molecular sieves;
[0011] The metal cations in the first and second metal inorganic salt solutions are Li + Ca 2+ Mg 2 + Zn 2+ Co 2+ Al 3+ Fe 2+ At least one of them.
[0012] The metal cations in the first and second metal inorganic salt solutions can be the same or different.
[0013] The inorganic metal salts in the first and second inorganic metal salt solutions are chloride salts.
[0014] In the cation replacement step, the molar ratio of Na-type molecular sieve to the first metal inorganic salt is (0.1-1) g:(0.01-0.05) mol.
[0015] The Na-type molecular sieve is at least one of Na-A molecular sieve, Na-X molecular sieve, and Na-Y molecular sieve.
[0016] In the cation replacement step, the standing replacement time is ≥0.1h, preferably 0.1~48h;
[0017] And / or, in the impregnation step, the impregnation time is ≥1 hour;
[0018] And / or, the temperature of the cation exchange and / or impregnation is 10–100°C;
[0019] And / or, the sintering temperature is 400-600℃, and the holding time at the sintering temperature is more than 1 hour, preferably 1-5 hours;
[0020] And / or, the sintering is carried out in a vacuum or protective atmosphere, preferably an inert gas or nitrogen;
[0021] The concentrations of the first and second metal inorganic salt solutions are 1 wt% or more, preferably 1 wt% to 80 wt%, and more preferably 1 wt% to 40 wt%.
[0022] The drying temperature is at least 110°C;
[0023] And / or, the drying time is ≥0.5h, preferably 0.5 to 12h.
[0024] A salt solution modified molecular sieve is prepared using the above-described preparation method.
[0025] The application of a salt solution modified molecular sieve in thermochemical thermal storage materials, preferably, the thermochemical thermal storage material is applied in thermochemical adsorption heat pumps, adsorption cold / heat storage devices, solar thermal utilization devices, and long-term transseasonal thermal storage devices.
[0026] The technical solution of this invention has the following advantages:
[0027] 1. This invention provides a method for preparing a salt solution-modified molecular sieve. By replacing the metal cations in a first inorganic metal salt containing specific metal cations with a Na-type molecular sieve, followed by sintering and infiltration, more second inorganic metal salts can be attached to the molecular sieve. This effectively solves the problem of low loading of inorganic metal salts in traditional molecular sieves, increases the loading capacity, and significantly improves the energy storage effect. Simultaneously, the salt solution-modified molecular sieve obtained by replacement modification, sintering, and infiltration in this invention does not suffer from leakage during hydration / desorption reactions. Furthermore, compared to individual molecular sieves and individual inorganic metal salts of the same content, the enthalpy of reaction of the salt solution-modified molecular sieve of this invention is significantly increased, which is significantly better than the heat storage density value of a heat storage material composed of a simple mixture of the two. Therefore, the modification method of this invention also effectively promotes a synergistic increase in adsorption heat storage density between the molecular sieve and the inorganic metal salt, with very significant effects.
[0028] 2. The preparation method provided by the present invention has the advantages of simple operation and easy scale-up. Attached Figure Description
[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0030] Figure 1 This is the XRD diffraction pattern of the molecular sieve modified by cation exchange with salt solution in Example 1 of this invention;
[0031] Figure 2 This is the isothermal adsorption / desorption curve of the thermochemical thermal storage material of the salt solution modified molecular sieve in Example 4 of the present invention;
[0032] Figure 3This is a comparison graph of the weight gain curves of the molecular sieve without salt solution modification in Comparative Example 1 and the modified molecular sieve in Example 4. Detailed Implementation
[0033] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.
[0034] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.
[0035] Example 1
[0036] A method for preparing salt solution modified molecular sieves, comprising:
[0037] (1) Cation replacement modification: Weigh 1g of Na-Y zeolite molecular sieve material and 3g of magnesium chloride. Accurately weigh the salt using a high-precision electronic balance and accurately measure the volume of deionized water using a graduated cylinder. Add magnesium chloride to the deionized water and stir in a beaker at room temperature until the solute is completely dissolved and no longer exothermic, thus preparing a 40% magnesium chloride solution. Add Na-Y zeolite molecular sieve to the magnesium chloride solution and let it stand and soak at 20°C for 6 hours. After standing and soaking, filter out the solution and wash the soaked molecular sieve with sufficient deionized water and filter again until the filtrate is completely clear.
[0038] (2) Sintering: The molecular sieve is transferred into an alumina crucible, and air is introduced into a tube furnace at 10℃·min. -1 Heat to 120℃ and maintain for 6 hours to dry thoroughly. After drying, calcine the molecular sieve at 400℃ for 4 hours in a tube furnace in the absence of air.
[0039] (3) Impregnation: A salt solution with a mass concentration of 30wt% is used for impregnation. Specifically, the salt solution is mixed with the calcined molecular sieve at 90℃ and impregnated for 1h. The salt in this step is a binary mixed salt composed of 80wt% MgCl2 and 20wt% MgSO4.
[0040] (4) Separation and drying: After impregnation, solid-liquid separation is carried out, and then drying is carried out at 110℃ for 3 hours.
[0041] Example 2
[0042] A method for preparing salt solution modified molecular sieves, comprising:
[0043] (1) Cation replacement modification: Weigh 1g of Na-X zeolite molecular sieve and 1g of calcium chloride. Accurately weigh the salt using a high-precision electronic balance and accurately measure the volume of deionized water using a graduated cylinder. Dissolve the calcium chloride in the deionized water in a beaker and stir at room temperature until the solute is completely dissolved and no longer exothermic, thus preparing a 1% calcium chloride solution. Add the Na-X zeolite molecular sieve and soak it at 10℃. After soaking for 6 hours, filter out the solution and wash the soaked molecular sieve with sufficient deionized water and filter again until the filtrate is completely clear. Repeat the soaking process several times. The XRD diffraction pattern of the replacement-modified molecular sieve is shown below. Figure 1 As shown.
[0044] (2) Sintering: The soaked molecular sieves are transferred into an alumina crucible, and air is introduced into a tube furnace at 5°C·min. -1 Heat to 110℃ and maintain for 12 hours to dry thoroughly. After drying, calcine the molecular sieve at 500℃ for 4 hours in a tube furnace in the absence of air.
[0045] (3) Impregnation: CaCl2 is filled into the calcined molecular sieve by salt solution impregnation. The salt solution is CaCl2 solution. During impregnation, the mass concentration of CaCl2 solution is 40%, and the impregnation is carried out at 30°C for 24 hours.
[0046] (4) Drying and separation: After impregnation, solid-liquid separation is carried out, and then drying is carried out at 110℃ for 10h.
[0047] Example 3
[0048] A method for preparing salt solution modified molecular sieves, comprising:
[0049] (1) Cation replacement modification: Weigh 0.5g of Na-Y zeolite molecular sieve material, stir it in a beaker at room temperature until the solute is completely dissolved and no more heat is released, and then prepare 30ml of magnesium chloride solution with a concentration of 1mol / L (mass concentration of 20%). Add Na-Y zeolite molecular sieve to the magnesium chloride solution and soak it at 30℃. After soaking for 2 hours, filter out the solution, wash the soaked molecular sieve with sufficient deionized water and filter it until the filtrate is completely clear.
[0050] (2) Sintering: The molecular sieve is transferred into an alumina crucible, and air is introduced into a tube furnace at 5°C·min. -1 Heat to 110℃ and maintain for 4 hours to dry thoroughly. After drying, calcine the molecular sieve at 600℃ for 1 hour in a tube furnace in the absence of air.
[0051] (3) Impregnation: A composite salt consisting of KCl / CaCl2 is filled into the calcined molecular sieve by a salt solution impregnation method. The mass ratio of KCl to CaCl2 in the composite salt is 2:1, the mass concentration of the salt solution is 40wt%, and the impregnation time is 12h at 80℃.
[0052] (4) Separation and drying: After impregnation, solid-liquid separation is carried out, and then drying is carried out at 110℃ for 4 hours.
[0053] Example 4
[0054] A method for preparing salt solution modified molecular sieves, comprising:
[0055] (1) Cation replacement modification: Weigh 0.1g of Na-Y zeolite molecular sieve material and 10g of magnesium chloride hexahydrate. Weigh the mass of the hydrated salt accurately using a high-precision electronic balance and measure the volume of deionized water accurately using a graduated cylinder. Dissolve magnesium chloride hexahydrate in deionized water to prepare a magnesium chloride solution with a mass concentration of 10%. Add Na-Y zeolite molecular sieve to the magnesium chloride solution and soak it at 30°C. After soaking for 2 hours, filter out the solution and wash the soaked molecular sieve with sufficient deionized water and filter it until the filtrate is completely clear.
[0056] (2) Sintering: The molecular sieve is transferred into an alumina crucible, and air is introduced into a tube furnace at 10℃·min. -1 Heat to 120℃ and maintain for 6 hours to dry thoroughly. After drying, calcine the molecular sieve at 400℃ for 4 hours in a tube furnace in the absence of air.
[0057] (3) Impregnation: The composite salt composed of MgCl2 / CaCl2 is filled into the calcined molecular sieve by the salt solution impregnation method. The molar ratio of MgCl2 to CaCl2 in the composite salt is 1:2, the mass concentration of the salt solution is 30wt%, and the impregnation is carried out at 70℃ for 1h.
[0058] (4) Separation and drying: After impregnation, solid-liquid separation is carried out, and then drying is carried out at 110℃ for 3 hours.
[0059] Comparative Example 1
[0060] The difference between this comparative example and Example 4 is that no cation replacement modification was performed; the Na-Y zeolite molecular sieve was directly sintered, while other conditions were the same as in Example 4.
[0061] Comparative Example 2
[0062] The difference between this comparative example and Example 4 is that the impregnation step is not performed; that is, the sintered molecular sieve is directly used as the salt solution modified molecular sieve. Other conditions are the same as in Example 4.
[0063] Experimental Example
[0064] The equilibrium adsorption capacity and reaction enthalpy of the molecular sieves modified with salt solutions from the above examples and comparative examples were determined. The specific detection methods are as follows:
[0065] The reaction enthalpy was detected using a simultaneous thermal analyzer. The reaction enthalpy of the salt solution modified molecular sieve was obtained by integrating the heat flow curve of the desorption process. The equilibrium adsorption capacity at 65RH% was determined under a water vapor atmosphere at 200℃. The test results are shown in Table 1.
[0066] Simultaneously, isothermal adsorption / desorption curves of the salt solution modified molecular sieve thermochemical heat storage material of Example 4 were obtained at different relative humidities at room temperature, such as... Figure 2 As shown; and the weight gain curves of the modified molecular sieve of Example 4 and the unmodified molecular sieve of Comparative Example 1 for the wet components were obtained, and the comparison results of the weight gain curves are shown in the figure. Figure 3 As shown.
[0067] Table 1
[0068]
[0069]
[0070] Through Table 1 and Figure 1-3 It is known that by modifying the Na-type molecular sieve with cation replacement through the first metal inorganic salt solution, the cations in the first metal inorganic salt can effectively replace the Na ions, thereby increasing the content of the second metal inorganic salt impregnated in the molecular sieve after subsequent sintering, and significantly improving its energy storage effect as a thermochemical heat storage material.
[0071] Specifically, comparing Example 4 and Comparative Example 1 in this invention, it can be seen that directly using unmodified Na-Y zeolite molecular sieves for subsequent sintering, infiltration, separation, and drying only increases the enthalpy of reaction of the Na-Y zeolite molecular sieve from 0.56 kJ / g to 0.78 kJ / g, an increase of less than 40%, which is not significant. Even with simple substitution modification of the Na-Y zeolite molecular sieve, the enthalpy of reaction only increases from 0.56 kJ / g to 0.63 kJ / g, a negligible increase. However, this invention, through a combination of substitution modification and infiltration, effectively increases the enthalpy of reaction of the Na-Y zeolite molecular sieve from 0.56 kJ / g to 1.3 kJ / g, an increase of 132%, which is a very significant improvement.
[0072] The present invention employs a combination of static displacement with a first metal inorganic salt solution and impregnation with a second metal inorganic salt solution, which is applicable to all Na-type molecular sieves and effectively and significantly improves the reaction enthalpy of the molecular sieve. Therefore, it is effectively used as a thermochemical heat storage material. Preferably, the thermochemical heat storage material is preferably applied in thermochemical adsorption heat pumps, adsorption cold / heat storage devices, solar thermal utilization devices, and long-term cross-seasonal heat storage devices.
[0073] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. The application of a salt solution-modified molecular sieve in thermochemical heat storage materials. Its features are, The method for preparing the salt solution modified molecular sieve includes: Cation exchange: The Na-type molecular sieve is replaced by a solution of the first metal inorganic salt by allowing it to stand for a period of time. Sintering: The replaced molecular sieve is calcined at a temperature above 400℃; Impregnation: The sintered molecular sieve is mixed with a second metal inorganic salt solution for impregnation; Separation and drying: After impregnation, separation and drying are carried out to obtain salt solution modified molecular sieves; The metal cations in the first and second metal inorganic salt solutions are Li + Ca 2+ Mg 2+ Zn 2 + Co 2+ Al 3+ Fe 2+ At least one of them.
2. The application according to claim 1, characterized in that, The inorganic metal salts in the first and second inorganic metal salt solutions are chloride salts.
3. The application according to claim 1 or 2, characterized in that, In the cation replacement step, the molar ratio of Na-type molecular sieve to the first metal inorganic salt is (0.1~1) g : (0.01~0.05) mol.
4. The application according to claim 1 or 2, characterized in that, The Na-type molecular sieve is at least one of Na-A molecular sieve, Na-X molecular sieve, and Na-Y molecular sieve.
5. The application according to claim 1 or 2, characterized in that, In the cation exchange step, the standing exchange time is ≥0.1 h; And / or, the temperature of the cation exchange and / or impregnation is 10~100℃; And / or, the sintering temperature is 400~600℃, and the holding time at the sintering temperature is more than 1 hour; And / or, the sintering is performed under a vacuum or protective atmosphere.
6. The application according to claim 5, characterized in that, In the cation replacement step, the standing replacement time is 0.1~48h; And / or, the sintering time is 1 to 5 hours; And / or, the protective atmosphere is an inert gas or nitrogen.
7. The application according to claim 1 or 2, characterized in that, The concentrations of the first and second metal inorganic salt solutions are 1 wt% or higher.
8. The application according to claim 7, characterized in that, The concentrations of the first and second metal inorganic salt solutions are 1 wt% to 80 wt%.
9. The application according to claim 8, characterized in that, The concentrations of the first and second metal inorganic salt solutions are 1 wt% to 40 wt%.
10. The application according to claim 1 or 2, characterized in that, The drying temperature is at least 110°C; And / or, the drying time is ≥0.5h.
11. The application according to claim 10, characterized in that, The drying time is 0.5 to 12 hours.
12. The application according to claim 1, characterized in that, The thermochemical thermal storage material is used in thermochemical adsorption heat pumps, adsorption cold / heat storage devices, solar thermal utilization devices, and long-term cross-seasonal thermal storage devices.