Production method of nano zeolite molecular sieve using waste zeolite molecular sieve catalyst as raw material and nano molecular sieve

Abstract

The present application relates to waste catalyst treatment field, disclose a kind of production method and nano molecular sieve using waste zeolite molecular sieve catalyst as raw material to prepare nano zeolite molecular sieve, the method comprises: (1) the waste zeolite molecular sieve catalyst of micron grade crystal grain size is calcined and impurity is removed;(2) subsequently it is placed into high-energy nanoscale ball mill and is ball milled, and the nanoscale amorphous fragment powder with crystal structure unit is obtained;(3) after the powder is mixed with water, alkali, structure directing agent, surfactant, and then hydrothermal crystallization is carried out by microwave irradiation;The frequency of microwave irradiation is above 433.92MHz, and the mass ratio of ball milling medium to raw material is above 3.The method of the present application can be used to synthesize nano molecular sieve using micron-sized raw materials.

Description

Technical Field

[0001] This invention relates to the field of waste catalyst treatment, specifically to a production method for preparing nano-zeolite molecular sieves using waste zeolite molecular sieve catalysts as raw materials, and a nano-molecular sieve. Background Technology

[0002] Zeolite molecular sieves are a class of microporous crystalline materials composed of TO4 tetrahedral structural units (T atoms include Si or Al). Due to the confinement effect of their micropores on molecular diffusion, the morphology and size of the molecular sieve greatly affect its adsorption and catalytic performance. Nanostructuring is a very effective solution, which is why nano-molecular sieves have become a hot topic in molecular sieve research in recent years. For example, small-crystal molecular sieves can be prepared by ball milling large-crystal molecular sieves and then recrystallizing them. However, there is currently limited research in this area. In addition, the structural and property changes of molecular sieves during ball milling are not well studied. Furthermore, the recycling of spent molecular sieve catalysts after use is also a problem.

[0003] CN202010813666.4 discloses a method for treating spent MTP catalyst. The method involves grinding the spent catalyst to reduce its average particle size to less than 10 μm, then calcining, acid washing, and recalcining the ground spent catalyst powder to further prepare HZSM 5 molecular sieve.

[0004] CN104973610A discloses a method for preparing nano ZSM-22 molecular sieves, which involves ball milling one-dimensional channel molecular sieves such as ZSM-22, ZSM-23, ZSM-48, EU-1, SAPO-11, and SAPO-41, and then using these as raw materials to synthesize ZSM-22 molecular sieves. Summary of the Invention

[0005] To address the problems of recycling and reusing spent zeolite molecular sieve catalysts and large-scale preparation of nano-zeolite molecular sieves in existing technologies, this invention provides a production method for preparing nano-zeolite molecular sieves using spent zeolite molecular sieve catalysts as raw materials. This method can recycle spent zeolite molecular sieve catalysts to prepare nano-zeolite molecular sieves.

[0006] To achieve the above objectives, the present invention provides a method for preparing nano-zeolite molecular sieves using waste zeolite molecular sieve catalyst as a raw material, the method comprising:

[0007] (1) The waste zeolite molecular sieve catalyst with micron-sized crystals was roasted to remove impurities;

[0008] (2) Then the calcined raw material is placed into the ball milling jar of the high-energy nano ball mill, the ball milling media is added, the ball milling jar is sealed, the motor switch is turned on, high-energy ball milling is carried out, the speed of the high-energy ball mill is adjusted, the ball milling time is controlled, and nano-scale amorphous fragment powder with crystal structure units is obtained.

[0009] (3) The amorphous fragment powder is then mixed with water, alkali, structure directing agent and surfactant, and then placed in a microwave synthesis vessel and sealed. It is then loaded into a microwave synthesizer (e.g., experimental type) and subjected to hydrothermal crystallization by microwave irradiation. The output power, temperature and heating time of microwave heating are controlled.

[0010] (4) Finally, the crystallized nano-zeolite molecular sieve product is obtained by centrifugation solid-liquid separation, washing and drying.

[0011] A second aspect of the present invention provides a molecular sieve produced by the production method of the present invention; preferably, the molecular sieve has a particle size of 50-500 nm and a specific surface area of ​​400-800 m². 2 / g, microporous specific surface area is 200-600m² 2 / g, mesoporous specific surface area 100-300m² 2 / g, with a pore volume of 0.3-0.5ml / g.

[0012] The method of this invention can synthesize nano-molecular sieves of various crystal forms, such as ZSM-5 and Beta, using micron-sized waste zeolite molecular sieve catalysts. Attached Figure Description

[0013] Figure 1 These are the XRD characterization spectra of the spent alkylated molecular sieve catalysts before and after ball milling in Examples 1 and 2, and the amorphous silica (alumina) gel in Comparative Example 1.

[0014] Figure 2 These are the UV-Raman spectra of the spent alkylated molecular sieve catalysts before and after ball milling in Examples 1 and 2, and the amorphous silica (alumina) gel in Comparative Example 1.

[0015] Figure 3 These are scanning electron microscope (SEM) images of amorphous fragments of the spent alkylated molecular sieve catalyst in Example 1 before and after ball milling for 3 hours.

[0016] Figure 4 This is a scanning electron microscope image of the nano ZSM-5 molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous material in Example 1.

[0017] Figure 5 The XRD spectrum is that of the nano ZSM-5 molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous material in Example 1.

[0018] Figure 6 This is a scanning electron microscope image of the nano-Beta molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous material in Example 21.

[0019] Figure 7 This is the XRD spectrum of the nano-Beta molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous material in Example 21.

[0020] Figure 8 This is a scanning electron microscope image of the ZSM-5 molecular sieve synthesized in Comparative Example 1 using ball-milled amorphous material and conventional hydrothermal synthesis, rather than microwave irradiation hydrothermal synthesis.

[0021] Figure 9 This is a scanning electron microscope image of the Beta molecular sieve synthesized by conventional hydrothermal method using ball-milled amorphous material in Comparative Example 2.

[0022] Figure 10 This is a scanning electron microscope image of the ZSM-5 molecular sieve synthesized by conventional hydrothermal method using amorphous silica-alumina gel as raw material in Comparative Example 3.

[0023] Figure 11 This is a scanning electron microscope image of the Beta molecular sieve synthesized using conventional hydrothermal methods from amorphous silica-alumina gel in Comparative Example 4. Detailed Implementation

[0024] This invention provides a method for preparing nano-zeolite molecular sieves using waste zeolite molecular sieve catalysts as raw materials, the method comprising:

[0025] (1) The waste zeolite molecular sieve catalyst with micron-sized crystals was roasted to remove impurities;

[0026] (2) Then the calcined raw material is placed into the ball milling jar of the high-energy nano ball mill, the ball milling media is added, the ball milling jar is sealed, the motor switch is turned on, high-energy ball milling is carried out, the speed of the high-energy ball mill is adjusted, the ball milling time is controlled, and nano-scale amorphous fragment powder with crystal structure units is obtained.

[0027] (3) The amorphous fragment powder is then mixed with water, alkali, structure directing agent and surfactant, and then placed in a microwave synthesis tank and sealed. It is then loaded into a microwave synthesizer and hydrothermal crystallization is carried out by microwave irradiation. The output power, temperature and heating time of microwave heating are controlled.

[0028] (4) Finally, through centrifugal solid-liquid separation, washing, drying and calcination, crystallized nano-zeolite molecular sieve products are obtained; the frequency of microwave irradiation is above 433.92MHz, and the mass ratio of ball milling media to raw materials is above 3.

[0029] In this invention, the ball milling conditions in step (2) can be conventionally chosen in the art. According to a preferred embodiment of this invention, the ball milling conditions in step (2) include: the ball milling media being 2-6 mm alumina microspheres; the mass ratio of raw material to ball milling media (referred to as the "ball milling ratio") being 1:3-20, preferably 1:4-10; the ball mill speed being 200-2000 rpm, preferably 300-1000 rpm; and the ball milling time being 1-8 h, preferably 2-3 h. By adopting the aforementioned preferred scheme, the spent molecular sieve catalyst can be ball milled into nanoscale amorphous fragment powder with crystalline structural units.

[0030] In this invention, the mixing conditions in step (3) can be conventionally chosen in the art. According to a preferred embodiment of the invention, the mixing conditions in step (3) include: magnetic stirring for 0.5 to 8 hours at a temperature of 0 to 80°C. By adopting the aforementioned preferred scheme, the raw materials can be mixed more uniformly.

[0031] In this invention, the microwave irradiation conditions can be conventionally selected in the art. According to a preferred embodiment of the invention, the microwave irradiation conditions include: a frequency between 433.92MHz and 2450MHz, and a power of 100-2100W, preferably 400-1500W.

[0032] According to the present invention, the preferred microwave irradiation time is 1-24 hours.

[0033] Furthermore, according to a preferred embodiment of the present invention, the conditions for microwave hydrothermal crystallization include: in a sealed microwave synthesis vessel, at a temperature of 60–200°C, preferably 120–180°C, with pressure and time determined according to specific needs, preferably under self-generated pressure, microwave irradiation crystallization for 1–24 hours.

[0034] According to a particularly preferred embodiment of the present invention, the production method wherein step (1) of calcining the waste zeolite molecular sieve catalyst with micron-sized grains to remove impurities includes calcining the waste zeolite molecular sieve catalyst with micron-sized grains at a temperature above 350°C, preferably 400-700°C, in an air atmosphere to remove impurities including organic matter and carbon.

[0035] By adopting the aforementioned preferred scheme, nanoscale zeolite molecular sieves can be prepared from waste zeolite molecular sieve catalysts, enabling the reuse of solid waste catalysts.

[0036] In this invention, the structure-directing agent can be any conventional choice in the art, as long as it achieves the objective of the invention. According to a preferred embodiment of the invention, the structure-directing agent is a quaternary ammonium base or an organic amine. There are no special requirements regarding the type of quaternary ammonium base or organic amine; the selection is based on the type of molecular sieve to be synthesized. There are no special requirements regarding the source and form of addition of the structure-directing agent; methods commonly used in the art can be employed.

[0037] By adopting the aforementioned preferred scheme, molecular sieves with different crystal structures can be synthesized.

[0038] In this invention, the surfactant can be any conventional choice in the art as long as it can achieve the purpose of this invention. According to a preferred embodiment of this invention, the surfactant is selected from one or more of the following: quaternary ammonium salt cationic surfactant CTAB, triblock copolymer nonionic surfactant P123 or F127.

[0039] According to a preferred embodiment of the present invention, the production method further includes the steps of separation, such as centrifugation, washing, and drying, after hydrothermal crystallization. By employing the aforementioned preferred embodiment, nano-molecular sieve products can be obtained.

[0040] In this invention, as long as the objective of this invention can be achieved, there are no special requirements on the mass ratio of the powder to water, alkali, structure directing agent, and surfactant. Preferably, on a dry basis, the mass ratio of structure directing agent to powder is 1 or more. According to a preferred embodiment of this invention, the mass ratio of powder (dry basis), caustic soda (dry basis), structure directing agent (dry basis), surfactant (dry basis) to water is 1:0.03~0.25:1~6:0~2:10~100. By adopting the aforementioned preferred scheme, amorphous powder can be effectively re-hydrothermally crystallized into molecular sieve.

[0041] According to a particularly preferred embodiment of the present invention, in the production method, the waste zeolite molecular sieve with micron-sized crystals is sourced from industrial molecular sieve waste catalysts such as those used in alkylation reactions, olefin cracking reactions, isomerization reactions, disproportionation reactions, selective catalytic cracking reactions, and methanol-to-gasoline reactions, preferably with a SiO2 content greater than 70% by weight in the industrial molecular sieve waste catalyst.

[0042] By adopting the aforementioned preferred scheme, the main content of molecular sieves in the waste catalyst raw material can be guaranteed, and the influence of binders and other agents can be reduced.

[0043] The method according to the present invention can synthesize nano-molecular sieves, and the synthesized molecular sieves have good physicochemical properties. Preferably, the particle size of the molecular sieves is 50-500 nm, and the specific surface area is 400-800 m². 2 / g, microporous specific surface area is 200-600m²2 / g, mesoporous specific surface area 100-300m² 2 / g, with a pore volume of 0.3-0.5ml / g.

[0044] In this invention, zeolite molecular sieve waste catalyst is ball-milled using a high-energy nanoball mill to obtain nano-amorphous powder. Unlike the amorphous silica-alumina gel raw material commonly used for synthesizing molecular sieves, this nano-amorphous powder, although its crystal structure collapses and is destroyed by physical ball milling, still contains molecular sieve microstructure units. It can be used as a special synthetic raw material, combined with microwave irradiation hydrothermal crystallization, to rapidly nucleate and grow, ultimately crystallizing to obtain nano-molecular sieves.

[0045] The present invention will be further illustrated below through specific embodiments:

[0046] (1) X-ray polycrystalline powder diffraction (XRD) characterization

[0047] The crystal structure of the samples was analyzed using a D8 Advance SS X-ray diffractometer from BRUKER GmbH, Germany. Using Cu Kα as the radiation source, the crystal form and framework structure of the molecular sieve were characterized at 40 kV and 40 mA, with diffraction angles of 2θ = 5–50°.

[0048] (2) Transmission electron microscopy (TEM) characterization

[0049] The microstructure of the samples was observed and photographed using a JEOL JEM-2100F transmission electron microscope.

[0050] (3) Specific surface area (BET) characterization

[0051] The specific surface area and pore size distribution of the samples were characterized using a Tristar 3000 specific surface area and pore size analyzer manufactured by Micromeritics, Inc.

[0052] (3) Ultraviolet Raman spectroscopy characterization

[0053] The ultraviolet Raman spectra were obtained using a three-monochrome Zolix UV-Raman-100 full-ultraviolet laser resonance Raman spectrometer with a spectral resolution of 3 cm⁻¹. -1 A Lexel 95SHG 244nm laser was used as the excitation source, with an output power of 30mW and a laser power of approximately 5.0MW.

[0054] Figure 1These are the XRD characterization spectra of the spent alkylated molecular sieve catalysts in Examples 1 and 2 before and after ball milling, and the amorphous silica (alumina) gel in Comparative Example 1. The results show that after ball milling, the molecular sieve structure is destroyed, the crystallinity decreases, and with the extension of time, it is completely destroyed until the crystallinity is zero, becoming an amorphous powder.

[0055] Figure 2 These are the UV-Raman spectra of the spent alkylated molecular sieve catalysts in Examples 1 and 2 before and after ball milling, and the amorphous silica (alumina) gel in Comparative Example 1. The results show that although the structure of the molecular sieve is destroyed after ball milling, the structural units still exist, unlike the amorphous silica (alumina) gel.

[0056] Figure 3 These are scanning electron microscope (SEM) images of amorphous fragments of the spent alkylation molecular sieve catalyst from Example 1 before and after ball milling for 3 hours. The results show that the molecular sieve structure was destroyed and the particle size decreased after ball milling.

[0057] Figure 4 These are scanning electron microscope images of the nano-ZSM-5 molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous powder as raw material in Example 1. The results show that the ZSM-5 molecular sieve synthesized using ball-milled amorphous powder as raw material has a crystal size in the nanometer range.

[0058] Figure 5 This is the XRD spectrum of the nano ZSM-5 molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous material in Example 1.

[0059] Figure 6 This is a scanning electron microscope image of the nano-Beta molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous powder as raw material in Example 21. The results show that the Beta molecular sieve synthesized using ball-milled amorphous powder as raw material has a crystal size in the nanometer range.

[0060] Figure 7 This is the XRD spectrum of the nano-Beta molecular sieve synthesized by microwave irradiation hydrothermal method using ball-milled amorphous material in Example 21.

[0061] Figure 8 This is a scanning electron microscope image of the ZSM-5 molecular sieve synthesized in Comparative Example 1 using ball-milled amorphous material and conventional hydrothermal synthesis, rather than microwave-irradiated hydrothermal synthesis. The results show that the ZSM-5 molecular sieve synthesized using conventional hydrothermal synthesis, rather than microwave-irradiated hydrothermal synthesis, has a grain size in the micrometer range.

[0062] Figure 9 The image shows a scanning electron microscope image of the Beta molecular sieve synthesized by conventional hydrothermal synthesis using ball-milled amorphous material in Comparative Example 2. The results show that the Beta molecular sieve synthesized by conventional hydrothermal synthesis rather than microwave irradiation hydrothermal synthesis has a grain size in the micrometer range.

[0063] Figure 10 This is a scanning electron microscope image of the ZSM-5 molecular sieve synthesized using amorphous aluminosilicate gel as raw material in Comparative Example 3 via conventional hydrothermal synthesis. The results show that the ZSM-5 molecular sieve synthesized using amorphous aluminosilicate gel as raw material via conventional hydrothermal synthesis has a grain size in the micrometer range.

[0064] Figure 11 This is a scanning electron microscope image of the Beta molecular sieve synthesized using amorphous aluminosilicate gel as raw material in Comparative Example 4 via conventional hydrothermal synthesis. The results show that the Beta molecular sieve synthesized using amorphous aluminosilicate gel as raw material via conventional hydrothermal synthesis has a grain size in the micrometer range.

[0065]

Example 1

[0066] 1. Take 1 kg of spent ZSM-5 zeolite molecular sieve catalyst from alkylation, with micron-sized crystals. Heat to 550℃ in an air atmosphere in a muffle furnace and calcine for 5 hours to remove organic matter and impurities such as carbon.

[0067] 2. Weigh 0.6 kg of calcined zeolite molecular sieve waste catalyst and put it into the ball mill jar of the high-energy nano ball mill. Add 3 kg of ball milling media: 4 mm alumina microspheres. Seal the ball mill jar, turn on the motor switch, and carry out high-energy ball milling. The ball mill speed is 600 rpm. Adjust the high-energy ball mill speed and the ball milling time is 3 hours.

[0068] Figure 1 XRD characterization showed that the crystal structure of this nanoscale amorphous powder collapsed and was destroyed. Figure 2 The ultraviolet-Raman spectroscopy characterization showed that it has crystalline structural units, which is different from the amorphous silica-alumina gel raw materials usually used to synthesize molecular sieves; Figure 3 Scanning electron microscope images of micron-sized ZSM-5 molecular sieves and nano-sized amorphous fragments obtained after ball milling the molecular sieves for 3 hours.

[0069] 3. Weigh 50g of nano amorphous powder, add 2kg of water, 8g of caustic soda, 125g of tetrapropylammonium hydroxide aqueous solution (TPAOH, 40%), and 80g of surfactant P123, and stir magnetically at room temperature for 2 hours.

[0070] 4. The mixture is placed in a microwave synthesis vessel and sealed. It is then loaded into an experimental microwave synthesizer and subjected to hydrothermal crystallization by microwave irradiation (frequency 2450MHz, power 500W) at a temperature of 120℃ and under autogenous pressure for 8 hours.

[0071] 5. Centrifugation, washing, drying, and calcination are performed to obtain nano ZSM-5 zeolite molecular sieve. Figure 4 and Figure 5The images show scanning electron microscope (SEM) images and XRD spectra of the synthesized nano ZSM-5 molecular sieves, respectively, indicating an average size of about 90 nanometers, classifying them as nanoscale molecular sieves.

[0072] The preparation and operating conditions are listed in Table 1. The specific surface area, pore size and average grain size of the synthesized molecular sieve are listed in Table 2. The specific surface area is 453.2 m² / g, which is higher than that of conventional molecular sieves of the same type (Comparative Examples 1 and 3).

[0073]

Examples 2-8

[0074] According to the synthesis method described in Example 1, the preparation conditions and operating conditions are shown in Table 1. Finally, a nano ZSM-5 molecular sieve product with an average particle size of less than 0.5 micrometers was synthesized. The specific surface area, pore size parameters and average crystal size of the product are listed in Table 2.

[0075]

Examples 9-14

[0076] Following the method described in Example 1, the preparation and operating conditions are shown in Table 1. Finally, a nano ZSM-5 molecular sieve product with an average particle size of less than 0.5 micrometers was synthesized. The specific surface area, pore size parameters, and average crystal size of the product are listed in Table 2.

[0077]

Examples 15-20

[0078] Following the synthesis method described in Example 1, the preparation and operating conditions are shown in Table 1. Finally, a nano ZSM-5 molecular sieve product with an average particle size of less than 0.5 micrometers was synthesized. The specific surface area, pore size parameters, and average crystal size of the product are listed in Table 2.

[0079]

Examples 21-25

[0080] Following the synthesis method described in Example 1, tetraethylammonium hydroxide (TEAOH, 40%) was used instead of tetrapropylammonium hydroxide aqueous solution. The preparation conditions and synthesis formula were changed. The preparation conditions and operating conditions are shown in Table 1. Finally, nano-Beta molecular sieves with an average particle size of less than 0.5 micrometers were synthesized. The specific surface area, pore size parameters and average crystal size and other texture parameters of the product are listed in Table 2.

[0081] Figure 6 and 7 The images show scanning electron microscope (SEM) images and XRD spectra of the nano-Beta molecular sieve synthesized in Example 21. The synthesized Beta zeolite molecular sieve has an average particle size of 160 nm, which is smaller than that of conventional molecular sieves of the same type, and a higher specific surface area than that of conventional molecular sieves of the same type (Comparative Examples 2 and 4).

[0082] Comparative Example 1

[0083] ZSM-5 molecular sieves were synthesized using amorphous silica-alumina gel as raw material via a conventional hydrothermal method, without ball milling or microwave irradiation hydrothermal crystallization. The synthesis ratio was the same as in Example 1. The preparation and operating conditions are shown in Table 3, and the specific surface area, pore size, and average grain size of the final molecular sieve product are listed in Table 4. Figure 8 The image shows a scanning electron microscope image of the synthesized ZSM-5 molecular sieve, with an average size in the micrometer range.

[0084] Comparative Example 2

[0085] Beta molecular sieves were synthesized using amorphous silica-alumina gel as raw material via a conventional hydrothermal method, without ball milling or microwave irradiation hydrothermal crystallization. The synthesis ratio was the same as in Example 21. The preparation and operating conditions are shown in Table 3, and the specific surface area, pore size, and average grain size of the final molecular sieve product are listed in Table 4. Figure 9 The image shows a scanning electron microscope image of the synthesized Beta molecular sieve, with an average size in the micrometer range.

[0086] Comparative Example 3

[0087] Using alkylated waste molecular sieve catalyst as raw material, amorphous powder was obtained by ball milling. This powder was then used to synthesize a molecular sieve using a conventional hydrothermal method, without microwave irradiation hydrothermal crystallization. Other operating conditions and synthesis ratios were the same as in Example 1. Preparation and operating conditions are shown in Table 3, and the specific surface area, pore size parameters, and average crystallite size of the final molecular sieve product are listed in Table 4.

[0088] Figure 10 The image shows a scanning electron microscope image of the ZSM-5 molecular sieve synthesized in Comparative Example 3. The average size of the molecular sieve is in the micrometer range.

[0089] Comparative Example 4

[0090] Using alkylated waste molecular sieve catalyst as raw material, amorphous powder was obtained by ball milling. This powder was then used to synthesize a molecular sieve using a conventional hydrothermal method, without microwave irradiation hydrothermal crystallization. Other operating conditions and synthesis ratios were the same as in Example 21. Preparation and operating conditions are shown in Table 3, and the specific surface area, pore size parameters, and average grain size of the final molecular sieve product are listed in Table 4.

[0091] Figure 11 The image shows a scanning electron microscope image of the synthesized Beta molecular sieve, with an average size in the micrometer range.

[0092] Comparative Example 5

[0093] ZSM-5 molecular sieves were synthesized using ball-milled amorphous powder as raw material, but the microwave irradiation hydrothermal crystallization frequency was 433.2 Hz, the power was 100 W, and the time was 2 h. Other operating conditions and synthesis ratios were the same as in Example 1. The preparation and operating conditions are shown in Table 3. The final product was amorphous and did not crystallize into a molecular sieve. Its specific surface area was very low, and the effect was poor. The parameters are listed in Table 4.

[0094] Comparative Example 6

[0095] ZSM-5 molecular sieves were synthesized using ball-milled amorphous powder as raw material, but the microwave irradiation hydrothermal crystallization temperature was set to 100℃. Other operating conditions and synthesis ratios were the same as in Example 1. The preparation and operating conditions are shown in Table 3. The final product was a partially crystallized molecular sieve. Its specific surface area and pore size parameters were low, resulting in poor performance. The parameters are listed in Table 4.

[0096] Comparative Example 7

[0097] ZSM-5 molecular sieves were synthesized using alkylation waste catalyst as raw material. The ball milling conditions were: ball milling ratio of 1:2, rotation speed of 100 rpm, and time of 1 hour. Other operating conditions and synthesis ratios were the same as in Example 1. The preparation and operating conditions are shown in Table 3. The specific surface area, pore size parameters, and average crystal size of the final molecular sieve product are listed in Table 4, and the results were poor.

[0098] Comparative Example 8

[0099] ZSM-5 molecular sieves were synthesized using alkylation waste molecular sieve catalysts as raw materials. The calcination was carried out in a muffle furnace at 300°C in air for 3 hours, lower than the temperature in Example 1. Other operating conditions and synthesis ratios were the same as in Example 1. The preparation and operating conditions are shown in Table 3, and the specific surface area, pore size, and average grain size of the final molecular sieve product are listed in Table 4. Because the calcination temperature was too low, carbonaceous impurities were not completely removed; therefore, the specific surface area was lower than in Example 1, and the grain size was also larger, resulting in poorer performance.

[0100] The results and comparisons in Tables 1 to 4 show that the molecular sieves synthesized using the method of this invention not only have small crystals but also high specific surface area, resulting in significantly better performance.

[0101] Table 1

[0102]

[0103]

[0104]

[0105]

[0106] Table 2

[0107]

[0108] Table 3

[0109]

[0110]

[0111] Table 4

[0112]

[0113]

[0114] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A production method for preparing nano-zeolite molecular sieves using waste zeolite molecular sieve catalyst as raw material, characterized in that, The method includes: (1) The waste zeolite molecular sieve catalyst with micron-sized crystals was roasted to remove impurities; (2) Then the calcined raw material is placed into the ball milling jar of the high-energy nano ball mill, the ball milling media is added, the ball milling jar is sealed, the motor switch is turned on, high-energy ball milling is carried out, the speed of the high-energy ball mill is adjusted, the ball milling time is controlled, and nano-scale amorphous fragment powder with crystal structure units is obtained. (3) After that, the amorphous fragment powder is mixed with water, alkali, structure directing agent and surfactant, and then put into a microwave synthesis tank and sealed. It is then loaded into a microwave synthesizer and hydrothermal crystallization is carried out by microwave irradiation. The output power, temperature and heating time of microwave heating are controlled. (4) Finally, the crystallized nano-zeolite molecular sieve product is obtained by centrifugal solid-liquid separation, washing, drying and calcination. The ball milling conditions in step (2) include: the mass ratio of raw material to ball milling media is 1:3 to 20; the ball mill speed is 200 to 2000 rpm; and the ball milling time is 1 to 8 hours. The conditions for microwave irradiation include a frequency of 433.92MHz-2450MHz.

2. The production method according to claim 1, wherein, The ball milling conditions in step (2) include: the ball milling media being 2-6 mm alumina microspheres; and / or, the mass ratio of raw material to ball milling media being 1:4-10; and / or, the ball mill speed being 300-1000 rpm; and / or, the ball milling time being 2-3 h.

3. The production method according to claim 1, wherein, The conditions for microwave irradiation include a power of 100-2100W.

4. The production method according to claim 3, wherein, The conditions for microwave irradiation include a power of 400-1500W.

5. The production method according to claim 1, wherein, The conditions for hydrothermal crystallization include: microwave irradiation crystallization for 1 to 24 hours in a sealed microwave synthesis vessel at a temperature of 120 to 180°C and under autogenous pressure.

6. The production method according to claim 1, wherein, Step (1) involves calcining the waste zeolite molecular sieve catalyst with micron-sized grains to remove impurities, including organic matter and carbon.

7. The production method according to claim 1, wherein, The structure directing agent is a quaternary ammonium base and / or an organic amine.

8. The production method according to claim 1, wherein, The surfactant is selected from one or more of the following: quaternary ammonium cationic surfactant CTAB, triblock copolymer nonionic surfactant P123, and triblock copolymer nonionic surfactant F127.

9. The production method according to claim 1, wherein, The method includes the steps of separation, washing, and drying after hydrothermal crystallization.

10. The production method according to claim 1, wherein, On a dry basis, the mass ratio of structure-directing agent to powder is greater than 1; The micron-sized waste zeolite molecular sieves are derived from one or more industrial molecular sieve waste catalysts from alkylation reactions, olefin cracking reactions, isomerization reactions, disproportionation reactions, selective catalytic cracking reactions, and methanol-to-gasoline reactions.

11. The production method according to claim 10, wherein, On a dry basis, the mass ratio of powder to caustic soda, structure-directing agent, surfactant, and water is 1:0.03~0.25:1~6:0~2:10~100.

12. The nano-molecular sieve produced by the production method according to any one of claims 1-11.

13. The molecular sieve according to claim 12, wherein, The molecular sieve has a particle size of 50-500 nm and a specific surface area of ​​400-800 m². 2 / g, microporous specific surface area is 200-600m² 2 / g, mesoporous specific surface area 100-300m² 2 / g, with a pore volume of 0.3-0.5ml / g.

Images