Zeolite seed crystal based on photo-initiation reaction and preparation method thereof

Abstract

The invention discloses a preparation method of zeolite seed crystal based on photo-initiation reaction, and the preparation method comprises the following steps: (1) dissolving fly ash and an alkaline compound in a solvent to obtain a mixed solution I; (2) adding a hydrogen peroxide solution and a template agent into the mixed solution I to obtain a mixed solution II; and (3) carrying out a reaction on the mixed solution II under an illumination initiation condition to obtain the zeolite seed crystal. According to the method, the fly ash is used as a raw material, the photoinitiator is added after alkali fusion treatment, and the zeolite seed crystal is prepared through illumination initiation of single crystals, so that compared with a traditional preparation method, the synthesis yield is higher, the conditions are milder, the crystallinity of the seed crystal is higher, and the problems of high energy consumption, low crystallization rate and low yield when the zeolite seed crystal is directly prepared from the fly ash at present are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of zeolite crystal seeds, and in particular to a method for preparing zeolite crystal seeds based on a light-initiated reaction. Background Art

[0002] Zeolite molecular sieves, as a new type of inorganic crystal material, are widely used in catalysis, adsorption and other fields due to their uniform pore structure and huge specific surface area. The preparation of zeolite molecular sieves with the assistance of zeolite seeds is an effective way to improve the crystallization rate and crystallinity of zeolite molecular sieves, and it can also effectively regulate the pore morphology and size of the molecular sieves. The principle of this method is to add a certain amount of pre-synthesized zeolite crystals as seeds during the synthesis process. These seeds act as nucleation sites, thereby promoting the rapid growth of zeolite molecular sieves. In traditional zeolite seed synthesis, since the nucleation stage requires a higher energy barrier, the hydrothermal crystallization method is often selected as the synthesis method, but this method has a high synthesis temperature, a long reaction time and a low yield.

[0003] In addition, the traditional zeolite seed synthesis method usually uses sodium aluminate and aluminum hydroxide as aluminum sources, silicon dioxide and sodium silicate as silicon sources, and sodium hydroxide or potassium hydroxide as alkali sources, which are often costly. Fly ash, as an industrial waste, usually has a specific silicon-aluminum ratio and uniform particle size, so it is easy to handle and has low cost. However, the effective components in fly ash are low, and the synthesized zeolite seed has low purity and poor performance. Summary of the invention

[0004] In order to solve the above technical problems, the object of the present invention is to provide a method for preparing zeolite seeds based on a photo-initiated reaction.

[0005] The above object of the present invention is achieved through the following technical solutions:

[0006] A method for preparing zeolite seeds based on a photo-initiated reaction comprises the following steps:

[0007] (1) dissolving fly ash and an alkaline compound in a solvent to obtain a mixed solution I;

[0008] (2) adding a hydrogen peroxide solution to the mixed solution I obtained in step (1) to obtain a mixed solution II;

[0009] (3) reacting the mixed solution II obtained in step (2) at 5-50° C. under light initiation conditions to obtain the zeolite seed crystals.

[0010] Photoinitiated reaction refers to a chemical reaction stimulated by light energy of a specific wavelength. In a photoinitiated reaction, free radicals, ions or other active intermediates can be generated after photons are absorbed, thereby initiating a series of chain chemical reactions. The in-situ hydrothermal synthesis of zeolite directly from a solution often has a low yield due to the lack of single crystal seed sites, while in a free radical-rich system, the instability of the solution itself makes it easier to produce single crystal seeds. Therefore, the present invention induces free radicals in mixed solution II through light irradiation, destroys the stability of the solution, and then produces single crystal zeolite seeds. The yield of zeolite seeds is higher and the conditions are milder. In addition, the preparation method uses fly ash as raw material, which reduces the synthesis cost while solving the problem of low yield of zeolite seeds synthesized directly from fly ash.

[0011] Furthermore, in step (1), the alkaline compound is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate. The alkaline compound can provide an alkaline environment to dissolve fly ash.

[0012] Furthermore, in step (1), the mass ratio of the fly ash to the alkaline compound is 1:(0.5-5).

[0013] Furthermore, in step (1), the solid-liquid ratio of the fly ash to the mixed liquid I is 1 g: (10-35) mL.

[0014] Furthermore, in step (1), the solvent is water.

[0015] Furthermore, in step (2), the mass percentage concentration of hydrogen peroxide in the hydrogen peroxide solution is 20 to 40%.

[0016] Furthermore, step (2) also includes the step of adding a template to the mixed solution I.

[0017] Furthermore, the template agent is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, triethylamine and tetrapropylammonium bromide.

[0018] Furthermore, in step (2), the volume ratio of the hydrogen peroxide solution to the mixed solution I is (0.1-5):25.

[0019] Furthermore, in step (3), the light source of the light-initiating condition is ultraviolet light with a wavelength of 10 to 400 nm and a light intensity of 0.1 to 1.2 mW / cm 2 .

[0020] Furthermore, in step (3), the light irradiation initiation condition is for a period of 1 to 72 hours.

[0021] Furthermore, in step (3), the zeolite seed crystals are MFI type zeolite seed crystals, SOD type zeolite seed crystals or FAU type zeolite seed crystals.

[0022] In a specific embodiment, in step (3), after centrifuging the mixed solution after light irradiation, the solid is washed with deionized water and 95% ethanol solution, and then dried to obtain zeolite seed crystals.

[0023] Beneficial effects of the present invention:

[0024] 1. The present invention uses fly ash zeolite seeds synthesized by light-initiated reaction, utilizes the coordinated action of light and hydrogen peroxide solution to generate free radicals, destroys the stability of the solution to form seeds, and can realize the synthesis of various types of zeolite seeds. On the one hand, the seeds can assist the formation of zeolite crystals, and on the other hand, the seeds can provide more attachment sites, which is conducive to the further modification of zeolite molecular sieves.

[0025] 2. The raw material fly ash used in the present invention is cheap and is one of the industrial wastes. It has the advantages of uniform particle size, low impurity content, and easy activation. The zeolite seed preparation process does not require the addition of additional silicon source and aluminum source, and does not require the use of additional complex modifiers. Compared with the existing zeolite seed synthesis technology, it not only simplifies the production process but also reduces production energy consumption and costs.

[0026] 3. Compared with the traditional hydrothermal method, the photo-induced reaction conditions used in the present invention are milder, have a higher yield, lower energy consumption in actual production, simpler production process, and lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the XRD pattern of the MFI zeolite seed prepared in Example 1.

[0028] Figure 2 This is the XRD pattern of the FAU type zeolite seed prepared in Example 4.

[0029] Figure 3 This is the XRD diagram of the SOD type zeolite seed prepared in Example 7. DETAILED DESCRIPTION

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0032] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0033] Example 1

[0034] A method for preparing MFI type zeolite seeds based on a photo-initiated reaction comprises the following steps:

[0035] (1) 1 g of fly ash, 2 g of sodium hydroxide and 1 g of potassium hydroxide were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0036] (2) adding 0.4 mL of 30% hydrogen peroxide solution and 0.2 g of tetramethylammonium hydroxide to the mixed solution I obtained in step (1) to obtain a mixed solution II;

[0037] (3) Place the borosilicate glass bottle in a room with a wavelength of 366 nm and an intensity of 0.4 mW / cm 2 The mixture was irradiated under a UV lamp at 25°C for 24 hours. The mixed solution after light irradiation was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain MFI type zeolite seed crystals.

[0038] Example 2

[0039] A method for preparing MFI zeolite seeds based on a light-initiated reaction is substantially the same as that of Example 1, except that in step (2), 2.4 mL of 30% hydrogen peroxide solution is added.

[0040] Example 3

[0041] A method for preparing MFI zeolite seeds based on a light-initiated reaction is substantially the same as that of Example 1, except that in step (2), 5 mL of 30% hydrogen peroxide solution is added.

[0042] Example 4

[0043] A method for preparing FAU type zeolite seeds based on a photo-initiated reaction comprises the following steps:

[0044] (1) 1 g of fly ash, 3.5 g of sodium hydroxide and 0.5 g of potassium hydroxide were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0045] (2) adding 3.2 mL of 30% hydrogen peroxide solution to the mixed solution I obtained in step (1) to obtain a mixed solution II;

[0046] (3) Place the borosilicate glass bottle in a room with a wavelength of 366 nm and an intensity of 0.1 mW / cm 2The mixture was irradiated at 40°C for 22 hours under a UV lamp. The mixed solution after light irradiation was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain FAU type zeolite seed crystals.

[0047] Example 5

[0048] A method for preparing FAU type zeolite seeds based on a photo-initiated reaction is basically the same as Example 4, except that in step (3), the intensity of the ultraviolet lamp is 0.4 mW / cm 2 .

[0049] Example 6

[0050] A method for preparing FAU type zeolite seeds based on light-initiated reaction is basically the same as Example 4, except that: in step (3), the intensity of the ultraviolet lamp is 1.2 mW / cm 2 .

[0051] Example 7

[0052] A method for preparing SOD type zeolite seed crystals based on a light-initiated reaction comprises the following steps:

[0053] (1) 1 g of fly ash and 4 g of sodium hydroxide were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0054] (2) adding 3 mL of 30% hydrogen peroxide solution to the mixed solution I obtained in step (1) to obtain a mixed solution II;

[0055] (3) Place the borosilicate glass bottle in a room with a wavelength of 366 nm and an intensity of 0.4 mW / cm 2 The mixture was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and then quickly dried to obtain SOD type zeolite seed crystals.

[0056] Example 8

[0057] A method for preparing SOD type zeolite seeds based on light-initiated reaction is basically the same as Example 7, except that: in step (3), irradiation is performed at 50° C. for 32 hours.

[0058] Example 9

[0059] A method for preparing SOD type zeolite seeds based on light-initiated reaction is basically the same as Example 7, except that: in step (3), irradiation is performed at 30° C. for 16 h.

[0060] Example 10

[0061] A method for preparing SOD type zeolite seeds based on light-initiated reaction is basically the same as Example 7, except that: in step (3), irradiation is performed at 30° C. for 48 hours.

[0062] Embodiment 11

[0063] A method for preparing SOD type zeolite seeds based on light-initiated reaction is basically the same as Example 7, except that: in step (3), irradiation is performed at 30° C. for 64 hours.

[0064] Comparative Example 1

[0065] A method for preparing MFI zeolite seeds based on a hydrothermal method comprises the following steps:

[0066] (1) 1 g of fly ash, 2 g of sodium hydroxide, 1 g of potassium hydroxide and 0.2 g of tetramethylammonium hydroxide were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0067] (2) The mixed solution I in step (1) was transferred to a polytetrafluoroethylene-lined hydrothermal synthesis reactor and crystallized at 170° C. for 72 h. The mixed solution after the reaction was centrifuged to separate the solid and the liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain MFI zeolite seed crystals.

[0068] Comparative Example 2

[0069] A method for preparing FAU type zeolite seed crystals based on a hydrothermal method comprises the following steps:

[0070] (1) 1 g of fly ash, 3.5 g of sodium hydroxide and 0.5 g of potassium hydroxide were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0071] (2) The mixed solution I in step (1) was transferred to a polytetrafluoroethylene-lined hydrothermal synthesis reactor and crystallized at 120° C. for 8 h. The mixed solution after the reaction was centrifuged to separate the solid and the liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain FAU type zeolite seed crystals.

[0072] Comparative Example 3

[0073] A method for preparing SOD type zeolite seed crystals based on a hydrothermal method comprises the following steps:

[0074] (1) 1 g of fly ash and 4 g of sodium hydroxide were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0075] (2) The mixed solution I in step (1) was transferred to a polytetrafluoroethylene-lined hydrothermal synthesis reactor and crystallized at 100° C. for 16 h. The mixed solution after the reaction was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain SOD type zeolite seed crystals.

[0076] Comparative Example 4

[0077] A method for preparing SOD type zeolite seeds based on light-initiated reaction is basically the same as Example 7, except that: in step (3), irradiation is performed at 70° C. for 32 hours.

[0078] Comparative Example 5

[0079] A method for preparing MFI type zeolite seeds based on chemical photoinitiated reaction, comprising the following steps:

[0080] (1) 5 g of sodium silicate, 3 g of sodium aluminate, 4 g of sodium hydroxide, 1 g of potassium hydroxide and 1 g of ammonium fluoride were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0081] (2) adding 2.4 mL of 30% hydrogen peroxide solution and 0.72 g of tetramethylammonium hydroxide to the mixed solution I obtained in step (1) to obtain a mixed solution II;

[0082] (3) Place the borosilicate glass bottle in a room with a wavelength of 366 nm and an intensity of 0.4 mW / cm 2 The mixture was irradiated under a UV lamp at 25°C for 24 hours. The mixed solution after light irradiation was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain MFI type zeolite seed crystals.

[0083] Comparative Example 6

[0084] A method for preparing FAU type zeolite seeds based on chemical light-initiated reaction, comprising the following steps:

[0085] (1) 7 g of sodium silicate, 3 g of sodium aluminate, 5 g of sodium hydroxide, 1.5 g of potassium hydroxide and 0.75 g of ammonium fluoride were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0086] (2) adding 3.2 mL of 30% hydrogen peroxide solution to the mixed solution I obtained in step (1) to obtain a mixed solution II;

[0087] (3) Place the borosilicate glass bottle in a room with a wavelength of 366 nm and an intensity of 0.4 mW / cm 2The mixture was irradiated at 40°C for 22 hours under a UV lamp. The mixed solution after light irradiation was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain FAU type zeolite seed crystals.

[0088] Comparative Example 7

[0089] A method for preparing SOD type zeolite seeds based on chemical light-induced reaction, comprising the following steps:

[0090] (1) 5 g of sodium silicate, 4 g of sodium aluminate, 6 g of sodium hydroxide, 0.5 g of potassium hydroxide and 1 g of ammonium fluoride were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0091] (2) adding 3 mL of 30% hydrogen peroxide solution to the mixed solution I obtained in step (1) to obtain a mixed solution II;

[0092] (3) Place the borosilicate glass bottle in a room with a wavelength of 366 nm and an intensity of 0.4 mW / cm 2 The mixture was irradiated at 60°C for 32 hours under a UV lamp. The mixed solution after light irradiation was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain SOD type zeolite seed crystals.

[0093] Comparative Example 8

[0094] A method for preparing MFI zeolite seeds based on a chemical hydrothermal method comprises the following steps:

[0095] (1) 5 g of sodium silicate, 3 g of sodium aluminate, 4 g of sodium hydroxide, 1 g of potassium hydroxide, 1 g of ammonium fluoride and 0.72 g of tetramethylammonium hydroxide were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0096] (2) The mixed solution I in step (1) was transferred to a polytetrafluoroethylene-lined hydrothermal synthesis reactor and crystallized at 170° C. for 72 h. The mixed solution after the reaction was centrifuged to separate the solid and the liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain MFI zeolite seed crystals.

[0097] Comparative Example 9

[0098] A method for preparing FAU type zeolite seeds based on a chemical hydrothermal method comprises the following steps:

[0099] (1) 7 g of sodium silicate, 3 g of sodium aluminate, 5 g of sodium hydroxide, 1.5 g of potassium hydroxide and 0.75 g of ammonium fluoride were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0100] (2) The mixed solution I in step (1) was transferred to a polytetrafluoroethylene-lined hydrothermal synthesis reactor and crystallized at 120° C. for 8 h. The mixed solution after the reaction was centrifuged to separate the solid and the liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain FAU type zeolite seed crystals.

[0101] Comparative Example 10

[0102] A method for preparing SOD type zeolite seeds based on a chemical hydrothermal method comprises the following steps:

[0103] (1) 5 g of sodium silicate, 4 g of sodium aluminate, 6 g of sodium hydroxide, 0.5 g of potassium hydroxide and 1 g of ammonium fluoride were placed in a borosilicate glass bottle, and 25 mL of deionized water was added to obtain a mixed solution I;

[0104] (2) The mixed solution I in step (1) was transferred to a polytetrafluoroethylene-lined hydrothermal synthesis reactor and crystallized at 100° C. for 16 h. The mixed solution after the reaction was centrifuged to separate the solid and liquid, and the solid was washed with deionized water and 95% ethanol solution, and quickly dried to obtain SOD type zeolite seed crystals.

[0105] Test Example 1

[0106] The crystal structures of the MFI zeolite seed crystals prepared in Example 1, the FAU zeolite seed crystals prepared in Example 4, and the SOD zeolite seed crystals prepared in Example 7 were observed by X-ray diffraction (XRD). Figure 1 to Figure 3 As shown by Figure 1 to Figure 3 It can be seen that the zeolite seeds prepared by photoinitiated reaction have a high degree of crystallinity, and the characteristic diffraction peaks are consistent with the standard diffraction peaks of MFI, FAU and SOD zeolites.

[0107] 1 g of the zeolite seeds prepared in Examples 1 to 11 and Comparative Examples 1 to 10 were taken to test the change in diffraction intensity by an X-ray diffractometer, and the relative crystallinity was calculated using the following formula:

[0108]

[0109] Wherein Xc is the relative crystallinity of the synthetic product, in %; X0 is the crystallinity of the standard sample of this type of crystal, in %; Ic is the diffraction intensity of a certain crystal plane (hkl) of the synthetic crystal; I0 is the diffraction intensity of a certain crystal plane (hkl) of the standard sample of this type of crystal.

[0110] The yield of the zeolite seeds prepared in Examples 1 to 11 and Comparative Examples 1 to 10 was calculated using the following formula:

[0111]

[0112] Where Wr is the yield of the synthetic product, in %; W a is the yield of a certain embodiment / comparative example, in g; W b The theoretical yield is based on 100% conversion of silicon into products.

[0113] The data of relative crystallinity and relative yield of zeolite seeds prepared in Examples 1 to 11 are shown in Table 1:

[0114] Table 1

[0115] type Crystallinity / % Relative yield / % Embodiment 1 (MFI type) 82.1 37.41 Embodiment 2 (MFI type) 97.3 89.10 Example 3 (MFI type) 65.6 66.12 Embodiment 4 (FAU type) 72.8 72.21 Embodiment 5 (FAU type) 98.1 91.20 Embodiment 6 (FAU type) 91.5 99.18 Example 7 (SOD type) 77.8 66.12 Embodiment 8 (SOD type) 99.4 88.30 Embodiment 9 (SOD type) 83.0 53.07 Example 10 (SOD type) 98.5 86.13 Example 11 (SOD type) 95.7 85.26

[0116] As can be seen from Table 1, the MFI seed crystals in Example 2, the FAU seed crystals in Example 5, and the SOD seed crystals in Example 8 have the highest crystallinity.

[0117] In Examples 1 to 3, if the concentration of the photoinitiator hydrogen peroxide is too low, the concentration of hydroxyl radicals in the solution will be too low, which is not conducive to the synthesis of seed crystals and also leads to a low yield of seed crystal synthesis. Increasing the concentration of hydrogen peroxide will be beneficial to seed crystal synthesis. If the concentration is too high, a large amount of hydroxyl radicals will be formed by ultraviolet induction, which will lead to uncontrollable reactions in the solution and a significant decrease in the crystallinity of the directional synthesized MFI-type seed crystals.

[0118] In Examples 4 to 6, the light intensity directly affects the rate at which the photoinitiator hydrogen peroxide is converted into hydroxyl radicals. When the light intensity is too low, the hydrogen peroxide-induced conversion rate is slow, resulting in low crystallinity and yield of the synthesized FAU-type seed crystals. If the light intensity is too high, free radicals are rapidly generated in the reaction solution, resulting in a large amount of impurities in the product FAU-type seed crystals, resulting in a higher yield.

[0119] In Examples 7 to 11, the photo-initiation temperature and time have a significant effect on the synthesis of the seed crystals. When the temperature is too low, the seed crystal conversion rate is slow; when the photo-initiation time is short, the seed crystals are not fully grown; when the time is greater than 32 hours, the SOD-type seed crystals have completed their growth, and the concentration of the effective components in the reaction solution is lower than the reaction limit, and the seed crystal growth almost stops. At this time, extending the time has almost no effect on the crystallinity and yield.

[0120] The data of relative crystallinity and yield of zeolite seeds prepared in Comparative Examples 1 to 10 are shown in Table 2:

[0121] Table 2

[0122] type Crystallinity / % Yield / % Embodiment 2 (MFI type) 97.3 89.10 Comparative Example 1 (MFI type) 74.4 59.16 Comparative Example 5 (MFI type) 98.2 84.39 Comparative Example 8 (MFI type) 96.3 85.27 Embodiment 5 (FAU type) 98.1 91.20 Comparative Example 2 (FAU type) 75.9 60.03 Comparative Example 6 (FAU type) 98.6 86.13 Comparative Example 9 (FAU type) 95.8 88.41 Embodiment 8 (SOD type) 99.4 88.30 Comparative Example 3 (SOD type) 72.8 63.51 Comparative Example 4 (SOD type) 63.2 37.41 Comparative Example 7 (SOD type) 99.7 88.74 Comparative Example 10 (SOD type) 97.5 83.79

[0123] In Table 2, Examples 2, 5, and 8 are respectively using fly ash as raw materials to synthesize seed crystals through photoinitiation reaction, Comparative Examples 1, 2, and 3 are respectively using fly ash as raw materials to synthesize seed crystals through traditional hydrothermal method, and Comparative Examples 5, 6, and 7 are respectively using chemicals such as sodium silicate and sodium aluminate as raw materials to synthesize seed crystals through photoinitiation reaction. Comparative Examples 8, 9, and 10 are respectively using chemicals such as sodium silicate and sodium aluminate as raw materials to synthesize seed crystals through traditional hydrothermal method. It can be seen from the data in Table 2 that the traditional hydrothermal synthesis method using fly ash as raw material has low crystallinity and yield of synthesized seed crystals. This is because the traditional hydrothermal method initiates the reaction by temperature control, which is less efficient than the free radical initiation reaction; in Comparative Example 4, since the photoinitiator hydrogen peroxide is not resistant to high temperature and is easily decomposed by heat, when the temperature is too high, hydrogen peroxide decomposes to generate oxygen and dissipates, resulting in a significant decrease in the effective concentration of free radicals in the reaction solution, and the crystallinity and relative yield of the product SOD type seed crystals are both reduced. When chemicals are used as raw materials, the ratio of silicon and aluminum elements in the reaction solution is easy to control and the concentration is high. The reaction rate of the traditional hydrothermal method and the photo-initiated reaction rate are fast, and the crystallinity and yield of the synthesized seeds are relatively good. However, due to the limitation that the traditional hydrothermal method triggers the reaction by temperature, when chemicals are used as raw materials, the crystallinity and yield of the photo-initiated synthetic seeds are generally slightly higher than those of the traditional hydrothermal synthesis method. Therefore, compared with the traditional hydrothermal method for synthesizing seeds, when chemicals are used as raw materials, the photo-initiated method does not significantly improve the crystallinity and yield of the product seeds; however, when fly ash is used as raw material, the photo-initiated method significantly improves the quality of its product seeds. In addition, compared with fly ash, the chemical synthesis process is complex and the cost is higher. When applied in large-scale production, the effect of chemicals and directly using fly ash to synthesize seeds is similar, but the cost of fly ash is lower. Therefore, the present invention also provides an effective solution for large-scale industrial production of seeds.

[0124] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art should understand that other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing zeolite seeds based on a photo-initiated reaction, characterized in that: The following steps are involved: (1) dissolving fly ash and an alkaline compound in a solvent to obtain a mixed solution I; (2) adding a hydrogen peroxide solution to the mixed solution I obtained in step (1) to obtain a mixed solution II; (3) reacting the mixed solution II obtained in step (2) at 5-50° C. under light initiation conditions to obtain the zeolite seed crystals.

2. The preparation method according to claim 1, characterized in that: In step (1), the alkaline compound is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

3. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of the fly ash to the alkaline compound is 1:(0.5-5).

4. The preparation method according to claim 1, characterized in that: In step (1), the solid-liquid ratio of the fly ash to the mixed solution I is 1 g: (10-35) mL.

5. The preparation method according to claim 1, characterized in that: In step (2), the mass percentage concentration of hydrogen peroxide in the hydrogen peroxide solution is 20 to 40%.

6. The preparation method according to claim 1, characterized in that: Step (2) also includes the step of adding a template to the mixed solution I.

7. The preparation method according to claim 6, characterized in that: The template agent is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, triethylamine and tetrapropylammonium bromide.

8. The preparation method according to claim 1, characterized in that: In step (2), the volume ratio of the hydrogen peroxide solution to the mixed solution I is (0.1-5):

25.

9. The preparation method according to claim 1, characterized in that: In step (3), the light source of the light initiation condition is ultraviolet light with a wavelength of 10 to 400 nm and a light intensity of 0.1 to 1.2 mW / cm 2 .

10. The preparation method according to claim 1, characterized in that: In step (3), the zeolite seed crystals are MFI type zeolite seed crystals, SOD type zeolite seed crystals or FAU type zeolite seed crystals.

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