CN115417422A - Preparation method of FAU type molecular sieve adsorbent and carbon dioxide adsorption performance thereof - Google Patents
Preparation method of FAU type molecular sieve adsorbent and carbon dioxide adsorption performance thereof Download PDFInfo
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- C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
- C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
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- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
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Abstract
The invention discloses a preparation method of an FAU type molecular sieve adsorbent and carbon dioxide adsorption performance thereof. The FAU type molecular sieve adsorbent is synthesized by taking a sodium source, an aluminum source, a silicon source and an alkali solution as raw materials through a sol-gel method combined with post-treatment. The FAU type molecular sieve adsorbent with high carbon dioxide adsorption capacity is synthesized by using cheap and easily-obtained industrial raw materials and utilizing a seed-gel method through an effective mode of introducing defect sites into the materials. The adsorbent shows stronger affinity and adsorption capacity to carbon dioxide in carbon dioxide adsorption, and is obviously stronger than a commercial FAU type molecular sieve. The used adsorbent can be regenerated by a simple heating or decompression desorption method to remove the carbon dioxide gas adsorbed on the surface.
Description
Technical Field
The invention belongs to the technical field of microporous materials, and particularly relates to preparation of an FAU type molecular sieve adsorbent and application of the FAU type molecular sieve adsorbent in a carbon dioxide adsorption process.
Background
Carbon dioxide is a primary greenhouse gas, and its excessive emissions pose serious environmental problems such as global warming. At the same time, carbon dioxide is a cheap, easily available, non-toxic and harmless carbon resource, which is in C 1 The synthesized chemical process has the characteristics of environmental friendliness and sustainability. Therefore, from the viewpoint of environmental protection and resource utilization, it is imperative to develop an efficient carbon dioxide capture technology in order to provide raw materials for industrial applications while controlling carbon dioxide emissions. The carbon dioxide capture technology adopted in the industry at present mainly adopts a chemical absorption method and a physical adsorption method, but the former method has the characteristic of high desorption energy consumption. Physical adsorption separation of CO is currently being investigated 2 The main classes of porous materials of (a) are metal organic framework Materials (MOFs), porous carbons and molecular sieves. Among the main advantages of molecular sieves are low cost, relatively high stability and ease of ion exchange, which at appropriate Si/Al facilitates the regulation of the energy of gas-solid separation, thereby increasing the gas separation efficiency, minimizing the energy required for adsorbent regeneration, and thus in CO 2 The adsorption separation field is widely applied. For example, US2882244 discloses various crystalline aluminosilicates for carbon dioxide adsorption and chinese patent CN101524638B discloses a submicron molecular sieve adsorbent.
The FAU type molecular sieve occupies an important position in a physical adsorption method by virtue of a unique structure. The FAU-type structure molecular sieve is a microporous material, belongs to the faujasite class, and comprises an X type and a Y type with different silicon-aluminum ratios. The framework of the composite material mainly comprises aluminosilicate and has a secondary structure of double six-membered rings and beta cages, and the beta cages are connected through the double six-membered rings to form a three-dimensional open framework structure. US2078639 proposes a type X molecular sieve for adsorbing carbon dioxide from an air stream. The FAU type molecular sieve provides abundant adsorption sites for the adsorption of carbon dioxide by virtue of the large specific surface area, however, how to create more adsorption sites and further improve the adsorption capacity is a difficult point for the synthesis of the molecular sieve. By adjusting Si/Al, the FAU type molecular sieve with larger carbon dioxide adsorption capacity can be synthesized, however, the Si/Al adjustment for synthesizing the FAU type molecular sieve has a certain range, and the molecular sieve is limitedCarbon dioxide adsorption capacity of (2). In 1980, hermann K.Beyer and Ita Belenykaja firstly proposed that powdery NaY zeolite is used as a raw material to prepare SiO by dealuminization and silicon supplementation reaction in a nitrogen flow containing silicon tetrachloride at 250-550 DEG C 2 /Al 2 O 3 >6. High silicon and all silicon Y-type molecular sieves. US58868818 describes a lithium ion-loaded SiO 2 /Al 2 O 3 A FAU type molecular sieve less than 3 for adsorbing carbon dioxide. Through the mode of soaking, will adsorb the position as many as possible and combine with FAU type molecular sieve, this makes the adsorption performance of carbon dioxide obtain promoting by a wide margin. However, this method makes dissociation energy of carbon dioxide large, which is not favorable for desorption of carbon dioxide. More defect sites, especially hydroxyl defects, are introduced into the molecular sieve, so that carbon dioxide adsorption is facilitated. Patent CN1248487 describes a method of treating a type a molecular sieve with an alkali solution, so that the adsorption amount and the adsorption speed of the type a molecular sieve to carbon dioxide are obviously increased. Hydroxyl reacts with carbon dioxide to generate carbonate in various forms, which is beneficial to the attachment of more gases, and the carbonate is easy to decompose at high temperature, so that the carbon dioxide is easy to desorb. Therefore, the FAU type molecular sieve is treated by alkali, so that the FAU type molecular sieve has more adsorption sites and is beneficial to desorption, and the existing problems of the FAU type molecular sieve adsorbent are expected to be solved.
Disclosure of Invention
The invention aims to overcome the defects of the existing FAU type molecular sieve adsorbent synthesis mode, break through the limitation of complex synthesis means, promote the adsorption to be carried out in the forward direction through a simple post-treatment mode, and enable the FAU type molecular sieve to have more excellent carbon dioxide adsorption capacity. The invention provides a preparation method of a molecular sieve adsorbent and adsorption performance of the molecular sieve adsorbent on carbon dioxide. The molecular sieve adsorbent has high adsorption capacity to carbon dioxide, low cost and no pollution, and the performance of the molecular sieve adsorbent exceeds that of a commercial FAU type molecular sieve adsorbent.
In order to achieve the purpose, the invention provides a preparation method of an FAU type molecular sieve adsorbent with high carbon dioxide adsorption capacity. The FAU type molecular sieve adsorbent is prepared by taking a sodium source, an aluminum source, a silicon source and an alkali solution as raw materials and combining a sol-gel method with a post-treatment mode.
According to a particular embodiment of the present invention, preferably, the preparation method comprises the steps of:
mixing a sodium source and an aluminum source, adding a silicon source for precipitation, or mixing the sodium source and the silicon source, adding the aluminum source for precipitation to obtain precursor seeds, and aging;
mixing a sodium source and an aluminum source, and then adding a silicon source for precipitation, or mixing the sodium source and the silicon source, and then adding the aluminum source for precipitation to obtain an initial sol;
mixing the precursor seeds and the initial sol to obtain final gel;
crystallizing, washing and drying the final gel to obtain a standard substance;
and adding an alkali solution into the standard substance, mixing, heating, washing and drying to obtain the FAU type molecular sieve adsorbent.
In the preparation method, more defect sites can be provided for the FAU type molecular sieve through the post-treatment of the alkali solution, and the adsorption of carbon dioxide is facilitated. Preferably, the aluminum source comprises one or a combination of two or more of sodium metaaluminate, aluminum hydroxide and aluminum powder, the silicon source comprises one or a combination of two or more of silica sol, tetraethyl orthosilicate and sodium silicate, and the sodium source comprises one or a combination of two or sodium hydroxide and sodium peroxide.
In the above preparation method, for the precursor seed, preferably, the molar ratio of the silicon source to the aluminum source is 7-9.5 based on the silicon element in the silicon source and the aluminum element in the aluminum source. The molar ratio of the sodium source to the aluminum source is 14-18.5 based on sodium element in the sodium source and aluminum element in the aluminum source.
In the above preparation method, it is preferable that, for the final gel, the molar ratio of the silicon source to the aluminum source is 2 to 4.5. The molar ratio of the sodium source to the aluminum source is (calculated by sodium element in the sodium source) and (calculated by aluminum element in the aluminum source) 2-4.5.
In the above preparation method, preferably, the crystallization temperature is 60 to 120 ℃, and the crystallization time is 10 to 24 hours.
In the above preparation method, preferably, the washing manner includes one or a combination of suction filtration and centrifugation.
In the above production method, preferably, the washing termination pH is 7 to 9.
In the above preparation method, preferably, the drying manner includes one or a combination of two of oven drying and freeze drying.
In the above preparation method, preferably, the alkali solution includes one or a combination of two of a sodium hydroxide solution, a potassium hydroxide solution, and an aqueous ammonia solution.
In the above production method, preferably, the temperature of the mixing heating is 80 to 100 ℃, and the time is preferably 3 hours.
In the above preparation method, preferably, the washing manner includes one or a combination of suction filtration and centrifugation.
In the above production method, preferably, the washing termination pH is 7 to 9.
In the above preparation method, preferably, the drying manner includes one or a combination of two of oven drying and freeze drying.
According to a specific embodiment of the present invention, preferably, the above preparation method can be performed according to the following specific steps:
mixing a sodium source and an aluminum source, adding the silicon source for precipitation, or mixing the sodium source and the silicon source, adding the aluminum source for precipitation to obtain precursor seeds, wherein the molar ratio of the silicon source to the aluminum source is 7-9.5 in terms of silicon element in the silicon source and aluminum element in the aluminum source, and the molar ratio of the sodium source to the aluminum source is 14-18.5 in terms of sodium element in the sodium source and aluminum element in the aluminum source; aging after obtaining precursor seeds; mixing a sodium source and an aluminum source, and then adding a silicon source for precipitation, or mixing the sodium source and the silicon source, and then adding the aluminum source for precipitation to obtain an initial sol; mixing the precursor seeds and the initial sol to obtain a final gel, wherein the molar ratio of the silicon source to the aluminum source is 2-4.5; crystallizing the final gel at 60-120 deg.C for 10-24 hr; the washing mode is selected from suction filtration and centrifugation, and the pH value of the washing is 7-9; drying modes comprise drying and freeze drying; obtaining a standard substance; adding an alkali solution into the standard substance, mixing and heating for 3 hours at the temperature of 80-100 ℃; the washing mode is selected from suction filtration and centrifugation, and the pH value of the washing is 7-9; drying and freeze-drying to obtain the FAU type molecular sieve adsorbent.
The invention provides an FAU type molecular sieve adsorbent with high carbon dioxide adsorption capacity, which is prepared by the method.
According to the specific embodiment of the invention, the adsorption capacity of the FAU type molecular sieve adsorbent for adsorbing carbon dioxide can reach 7.18mmol/g.
Drawings
FIG. 1 is a schematic diagram of the mechanism of the absorption process of carbon dioxide by the FAU type molecular sieve adsorbent of the present invention;
FIG. 2 is an XRD pattern of adsorption of the FAU-type molecular sieve of the present invention;
FIG. 3 is N of the FAU type molecular sieve of the present invention 2 Adsorption and desorption isotherm diagram;
FIG. 4 is a hydroxyl infrared diagram of a FAU-type molecular sieve of the present invention;
FIG. 5 is a drawing of carbon dioxide adsorption of the FAU type molecular sieve of the present invention;
FIG. 6 is a table of parameters of the properties of the FAU-type molecular sieves of the present invention.
Detailed Description
The features and principles of the present invention are described below, and the examples are provided for illustration only and are not intended to limit the scope of the invention.
Example 1
This example provides an FAU type molecular sieve adsorbent prepared by the following steps:
(1) And synthesizing precursor seeds:
sequentially adding 6.96g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 19.9g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 18.5g of silica sol (30 percent), and uniformly mixing;
(2) Aging:
stirring the obtained solution for 1 hour, stopping stirring, standing and aging for 24 hours;
(3) And synthesizing initial sol:
sequentially adding 1.11g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 17.18g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 6.82g of silica sol, and stirring for 1 hour;
(4) Synthesis of the final gel:
adding precursor seeds into the initial sol, and continuously stirring for 1 hour;
(5) And crystallizing:
putting the mixture into an oven, and crystallizing the mixture for 18 hours at 80 ℃;
(6) And collecting standard substances:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
(7) Alkali treatment of the sample:
adding 0.25mol/L sodium hydroxide solution, heating at 95 ℃ for 3 hours, and continuously stirring;
(8) And collecting a sample:
washing the sample by deionized water, carrying out suction filtration until the pH value of the leachate is 7, stopping washing, and drying for 24 hours at 100 ℃;
the sample treated with 0.25mol/L NaOH solution was designated ATY-1.
Example 2
This example provides an FAU type molecular sieve adsorbent prepared by the following steps:
(1) And synthesizing precursor seeds:
sequentially adding 6.96g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 19.9g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 18.5g of silica sol (30 percent), and uniformly mixing;
(2) Aging:
stirring the obtained solution for 1 hour, stopping stirring, standing and aging for 24 hours;
(3) And synthesizing initial sol:
sequentially adding 1.11g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 17.18g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 6.82g of silica sol, and stirring for 1 hour;
(4) Synthesis of the final gel:
adding precursor seeds into the initial sol, and continuously stirring for 1 hour;
(5) And crystallizing:
putting the mixture into an oven, and crystallizing the mixture for 18 hours at 80 ℃;
(6) And collecting standard substances:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
(7) Alkali treatment of the sample:
adding 0.5mol/L sodium hydroxide solution, heating at 95 ℃ for 3 hours, and continuously stirring;
(8) And collecting a sample:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
the sample treated with 0.5mol/L NaOH solution was designated ATY-2.
Example 3
This example provides a FAU-type molecular sieve adsorbent prepared by the following steps:
(1) And synthesizing precursor seeds:
sequentially adding 6.96g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 19.9g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 18.5g of silica sol (30 percent), and uniformly mixing;
(2) Aging:
stirring the obtained solution for 1 hour, stopping stirring, standing and aging for 24 hours;
(3) And synthesizing initial sol:
sequentially adding 1.11g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 17.18g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 6.82g of silica sol, and stirring for 1 hour;
(4) Synthesis of the final gel:
adding precursor seeds into the initial sol, and continuously stirring for 1 hour;
(5) And crystallizing:
putting into a baking oven, and crystallizing at 80 ℃ for 18 hours;
(6) And collecting a standard substance:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
(7) Alkali treatment of the sample:
adding 0.75mol/L sodium hydroxide solution, heating at 95 ℃ for 3 hours, and continuously stirring;
(8) And collecting a sample:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
the sample treated with 0.75mol/L NaOH solution was designated ATY-3.
Example 4
This example provides a FAU-type molecular sieve adsorbent prepared by the following steps:
(1) And synthesizing precursor seeds:
sequentially adding 6.96g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 19.9g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 18.5g of silica sol (30 percent), and uniformly mixing;
(2) Aging:
stirring the obtained solution for 1 hour, stopping stirring, standing and aging for 24 hours;
(3) And synthesizing initial sol:
sequentially adding 1.11g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 17.18g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 6.82g of silica sol, and stirring for 1 hour;
(4) Synthesis of the final gel:
adding precursor seeds into the initial sol, and continuously stirring for 1 hour;
(5) And crystallizing:
putting the mixture into an oven, and crystallizing the mixture for 18 hours at 80 ℃;
(6) And collecting standard substances:
washing the sample by deionized water, carrying out suction filtration until the pH value of the leachate is 7, stopping washing, and drying for 24 hours at 100 ℃;
(7) Alkali treatment of the sample:
adding 1mol/L sodium hydroxide solution, heating for 3 hours at 95 ℃, and continuously stirring;
(8) And collecting a sample:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
the sample treated with 1mol/L sodium hydroxide solution was designated ATY-4.
Example 5
This example provides an FAU type molecular sieve adsorbent prepared by the following steps:
(1) And synthesizing precursor seeds:
sequentially adding 6.96g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 19.9g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 18.5g of silica sol (30 percent), and uniformly mixing;
(2) Aging:
stirring the obtained solution for 1 hour, stopping stirring, standing and aging for 24 hours;
(3) And synthesizing initial sol:
sequentially adding 1.11g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 17.18g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 6.82g of silica sol, and stirring for 1 hour;
(4) Synthesis of the final gel:
adding precursor seeds into the initial sol, and continuously stirring for 1 hour;
(5) And crystallizing:
putting the mixture into an oven, and crystallizing the mixture for 18 hours at 80 ℃;
(6) And collecting standard substances:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
(7) Alkali treatment of the sample:
adding 2mol/L sodium hydroxide solution, heating for 3 hours at 95 ℃, and continuously stirring;
(8) And collecting a sample:
washing the sample by deionized water, carrying out suction filtration until the pH value of the leachate is 7, stopping washing, and drying for 24 hours at 100 ℃;
the sample treated with 2mol/L NaOH solution was designated ATY-5.
Example 6
This example provides a FAU-type molecular sieve adsorbent prepared by the following steps:
(1) And synthesizing precursor seeds:
sequentially adding 6.96g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 19.9g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 18.5g of silica sol (30 percent), and uniformly mixing;
(2) Aging:
stirring the obtained solution for 1 hour, stopping stirring, standing and aging for 24 hours;
(3) And synthesizing initial sol:
sequentially adding 1.11g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 17.18g of deionized water while stirring, dropwise adding 6.82g of silica sol after stirring until the mixture is clear, and stirring for 1 hour;
(4) Synthesis of the final gel:
adding precursor seeds into the initial sol, and continuously stirring for 1 hour;
(5) And crystallizing:
putting the mixture into an oven, and crystallizing the mixture for 18 hours at 80 ℃;
(6) And collecting standard substances:
washing the sample by deionized water, carrying out suction filtration until the pH value of the leachate is 7, stopping washing, and drying for 24 hours at 100 ℃;
(7) Alkali treatment of the sample:
adding 3mol/L sodium hydroxide solution, heating at 95 ℃ for 3 hours, and continuously stirring;
(8) And collecting a sample:
washing the sample by deionized water, carrying out suction filtration until the pH value of the leachate is 7, stopping washing, and drying for 24 hours at 100 ℃;
the sample treated with 3mol/L NaOH solution was designated ATY-6.
Comparative example 1
This example provides a reference sample of FAU-type molecular sieve prepared by the following steps:
(1) And synthesizing precursor seeds:
sequentially adding 6.96g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 19.9g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 18.5g of silica sol (30 percent), and uniformly mixing;
(2) Aging:
stirring the obtained solution for 1 hour, stopping stirring, standing and aging for 24 hours;
(3) And synthesizing initial sol:
sequentially adding 1.11g of sodium hydroxide and 0.82g of sodium metaaluminate, adding 17.18g of deionized water while stirring, stirring until the mixture is clear, dropwise adding 6.82g of silica sol, and stirring for 1 hour;
(4) Synthesis of the final gel:
adding precursor seeds into the initial sol, and continuously stirring for 1 hour;
(5) And crystallizing:
putting the mixture into an oven, and crystallizing the mixture for 18 hours at 80 ℃;
(6) And collecting standard substances:
washing the sample with deionized water, filtering until the pH value of the leaching solution is 7, stopping washing, and drying at 100 ℃ for 24 hours;
the sample not treated with the sodium hydroxide solution was designated as NaY as a comparative example.
And (3) characterization:
characterization of FAU-type molecular sieve adsorbent
FIG. 2 is an XRD pattern of examples 1, 2, 3, 4, 5, 6 and comparative example 1; FIG. 3 shows N in examples 1, 2, 3, 4, 5, 6 and comparative example 1 2 Adsorption and desorption isotherm diagram; FIG. 4 is a hydroxyl group infrared chart of examples 1, 2, 3, 4, 5, 6 and comparative example 1; FIG. 5 is a drawing showing carbon dioxide adsorption in examples 1, 2, 3, 4, 5, and 6 and comparative example 1, wherein static carbon dioxide adsorption is performed by using a physical adsorption apparatus to measure the carbon dioxide adsorption amount at a temperature of 0 ℃ and an operating pressure of 250mmHg, in accordance with Standard HG/T2690-2012 issued by the Industrial & Informational Commission; FIG. 6 is a table of property parameters for examples 1, 2, 3, 4, 5, 6 and comparative example 1.
As can be seen from fig. 2 and fig. 6, all the examples and comparative examples have the structure of the typical FAU-type molecular sieve, and the crystallinity of the samples after alkali treatment does not significantly decrease, which indicates that the synthesized FAU-type molecular sieve has stable structure and provides possibility for further modifying the material. Meanwhile, the crystallinity is maintained to be basically stable, and the influence of the adsorption amount caused by the change of the crystallinity can be eliminated.
As can be seen from FIG. 3 in combination with FIG. 6, the samples of all examples had composite adsorption and desorption isotherms of type I and type IV, with the hysteresis loop appearing at P/P 0 After =0.8, it is indicated that the mesopores in the material are mainly intergranular mesopores. The specific surface area of the embodiment shows irregular change along with the increase of the concentration of the alkali liquor in the alkali treatment, but shows an increasing trend on the absorption capacity of the carbon dioxide, which indicates that the increase of the specific surface area is not the key reason for the increase of the adsorption quantity of the carbon dioxide. The micropore volume is basically kept unchanged along with the difference of the alkali treatment degree, and the introduction of the alkali does not have great influence on the interior of the FAU type molecular sieve adsorbent.
As can be seen from FIG. 4 in conjunction with FIG. 6, the wave number is 3733cm according to the rule of infrared spectrum research -1 Is a characteristic region of silicon hydroxyl infrared wave number, wherein the wave number is 3680cm -1 、3673cm -1 Characteristic region corresponding to infrared wave number of aluminum hydroxyl. Comparative example1, which indicates that the internal growth of the sample is uniform without excessive defects. With the mention of the concentration of the alkaline solution in the alkaline treatment, the concentration of the aluminum hydroxyl groups in the examples shows an upward trend, which is consistent with the increase of the carbon dioxide adsorption amount, and shows that the change of the carbon dioxide adsorption amount has a main influence factor of the concentration of the aluminum hydroxyl groups. The hydroxyl group concentration of example 6 is reduced compared with that of example 5 due to the preparation conditions, and the adsorption amount of carbon dioxide is reduced, which further shows that the aluminum hydroxyl group concentration is a key factor influencing the adsorption amount of carbon dioxide.
As can be seen from fig. 5 in conjunction with fig. 6, the adsorption capacity of carbon dioxide of the example is significantly stronger than that of the comparative example, and the highest adsorption amount appears in example 5, reaching 7.18mmol/g, which is significantly better than that of the commercial FAU type molecular sieve adsorbent. The used adsorbent can be regenerated by simple heating or decompression desorption to remove the carbon dioxide gas adsorbed on the surface.
According to the embodiment, the preparation method provided by the invention comprises the steps of mixing a sodium source and an aluminum source, adding a silicon source for precipitation to respectively obtain a precursor seed and an initial sol, mixing the precursor seed and the initial sol to obtain a final gel, and crystallizing and performing alkali treatment on the final gel to obtain the FAU type molecular sieve adsorbent. The method has the advantages of cheap and easily obtained raw materials, simple operation, suitability for industrial production and the like.
The foregoing is only a preferred embodiment of the present invention and it should be noted that modifications and improvements can be made by those skilled in the art without departing from the principle of the present invention and should be considered as the protection scope of the present invention.
Claims (8)
1. A preparation method of an FAU type molecular sieve adsorbent with high carbon dioxide adsorption capacity is characterized in that a sodium source, an aluminum source, a silicon source and an alkali solution are used as raw materials, and the FAU type molecular sieve adsorbent is prepared by combining a sol-gel method and a post-treatment mode.
2. The method for preparing an FAU-type molecular sieve adsorbent according to claim 1, comprising the steps of:
mixing a sodium source and an aluminum source, adding a silicon source for precipitation, or mixing the sodium source and the silicon source, adding the aluminum source for precipitation to obtain precursor seeds, and aging;
mixing a sodium source and an aluminum source, and then adding a silicon source for precipitation, or mixing the sodium source and the silicon source, and then adding the aluminum source for precipitation to obtain an initial sol;
mixing the precursor seeds and the initial sol to obtain final gel;
crystallizing, washing and drying the final gel to obtain a standard substance;
and adding an alkali solution into the standard substance, mixing, heating, washing and drying to obtain the FAU type molecular sieve adsorbent.
3. The preparation method according to claim 2, wherein the aluminum source comprises one or a combination of two or more of sodium metaaluminate, aluminum hydroxide and aluminum powder;
the silicon source comprises one or the combination of more than two of silica sol, tetraethyl orthosilicate and sodium silicate;
the sodium source comprises one or a combination of two of sodium hydroxide and sodium peroxide.
4. The preparation method according to any one of claims 1 to 3, wherein the molar ratio of the silicon source to the aluminum source, calculated as the silicon element in the silicon source and the aluminum element in the aluminum source, is from 0.001 to 9.5, preferably from 7 to 9.5; the molar ratio of the sodium source to the aluminum source is 0.001-18.5, preferably 14-18.5.
5. The preparation method according to any one of claims 1 to 4, wherein the molar ratio of the silicon source to the aluminum source, calculated as the silicon element in the silicon source and the aluminum element in the aluminum source, is from 0.001 to 4.5, preferably from 2 to 4.5; the molar ratio of the sodium source to the aluminum source is 0.001-4.5, preferably 2-4.5.
6. The process according to claim 2, wherein the crystallization temperature is 60-120 ℃, and the crystallization time is preferably 10-24 hours; the washing mode comprises one or the combination of suction filtration and centrifugation; the end pH of the wash is 7-9; the drying mode comprises one or two of drying and freeze drying.
7. The production method according to any one of claim 2, wherein the alkali solution comprises one or a combination of two of a sodium hydroxide solution, a potassium hydroxide solution, and an aqueous ammonia solution; the mixing and heating temperature is 80-100 ℃, and the preferred time is 3 hours; the washing mode comprises one or the combination of suction filtration and centrifugation; the end pH of the wash is 7-9; the drying mode comprises one or two of drying and freeze drying.
8. An FAU-type molecular sieve adsorbent having a high carbon dioxide adsorption capacity, prepared by the method of any of claims 1-7.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1785808A (en) * | 2004-12-09 | 2006-06-14 | 中国石油天然气股份有限公司 | Preparation method of high silicon aluminium ratio small crystal NaY molecular sieve |
| JP2008230886A (en) * | 2007-03-20 | 2008-10-02 | Jgc Catalysts & Chemicals Ltd | Synthesis method of minute faujasite-type zeolite |
| CN101543761A (en) * | 2009-03-25 | 2009-09-30 | 太原理工大学 | Method for improving adsorption quantity of high zeolite carbon dioxide |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1785808A (en) * | 2004-12-09 | 2006-06-14 | 中国石油天然气股份有限公司 | Preparation method of high silicon aluminium ratio small crystal NaY molecular sieve |
| JP2008230886A (en) * | 2007-03-20 | 2008-10-02 | Jgc Catalysts & Chemicals Ltd | Synthesis method of minute faujasite-type zeolite |
| CN101543761A (en) * | 2009-03-25 | 2009-09-30 | 太原理工大学 | Method for improving adsorption quantity of high zeolite carbon dioxide |
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