A method for preparing ZSM-5 molecular sieve by using catalytic cracking catalyst sludge as raw material

Abstract

The application belongs to the field of zeolite molecular sieve synthesis, and particularly relates to a method for preparing ZSM-5 molecular sieve by using catalytic cracking catalyst glue residue as raw material. The ZSM-5 molecular sieve is prepared by using catalytic cracking catalyst glue residue as silicon and aluminum raw material and through hydrothermal crystallization with a lower silicon aluminum ratio. The method fully utilizes the silicon and aluminum elements in the glue residue at a lower cost, and the prepared ZSM-5 molecular sieve has higher hydrothermal stability, which not only widens the raw material source of the ZSM-5 molecular sieve, but also realizes full utilization of the glue residue and reduction of the preparation cost.

Description

Technical Field

[0001] This invention belongs to the field of low-cost synthesis of zeolite molecular sieves and recycling and application of solid waste, and specifically relates to a method for preparing ZSM-5 molecular sieves using catalytic cracking catalyst residue as raw material. Background Technology

[0002] Zeolites are framework-structured silicate minerals and are typical porous materials. Microporous natural zeolites were first discovered, and through long-term practical experience, people gained some understanding of their properties, such as their adsorption properties. With the discovery of abundant natural zeolite resources, the utilization of natural zeolites has attracted widespread attention, leading to considerable research and significant progress. Their applications are expanding, including gas and liquid drying and separation, hard water softening, wastewater treatment, and as catalysts and catalyst supports. Because natural zeolites cannot meet large-scale industrial needs, research on the "geomorphic" synthesis of zeolites began. Subsequently, researchers employed various methods, such as hydrothermal, solvothermal, sol-gel, and dry gel methods, with the hydrothermal method being the most common, synthesizing different types of "synthetic zeolites" (such as X-type and Y-type molecular sieves, L-type molecular sieves, ZSM-5, mordenite, etc.). These zeolites possess regular channel structures, including the shape and size of channels and windows, channel orientation, channel dimension, pore wall properties, and composition.

[0003] ZSM-5 molecular sieve is a zeolite molecular sieve with a unique three-dimensional pore structure. Its unique pore structure is formed by the interlocking combination of two types of ten-membered ring-shaped channels: one is a near-cylindrical channel with a diameter of 0.56 nm × 0.53 nm, and the other is a "Z"-shaped channel with a diameter of 0.55 nm × 0.51 nm. This unique pore structure determines ZSM-5 molecular sieve's excellent shape selectivity. This significant characteristic allows ZSM-5 molecular sieve to maximize the yield of alkylbenzenes at the corresponding substitution positions in the catalytic reactions of aromatic alkylation, disproportionation, and isomerization. ZSM-5 molecular sieve is also a high silica-to-alumina ratio molecular sieve; experimental studies have shown that a higher silica-to-alumina ratio results in better thermal and hydrothermal stability.

[0004] The synthesis methods of ZSM-5 molecular sieves are mainly divided into hydrothermal synthesis, non-aqueous solvent system synthesis, microwave-assisted synthesis, template agent method, and template-free method. The raw materials used in their synthesis are mostly analytical grade reagents, such as sodium silicate, water glass, silica sol, sodium aluminate, sodium sulfate, tetraethyl orthosilicate, etc. Existing literature and patents also record the preparation of ZSM-5 molecular sieves using fly ash, rice husks, aluminum waste, or other raw materials. However, no one has yet reported preparing ZSM-5 molecular sieves using catalytic cracking catalyst residue. This invention analyzes the composition of the residue and finds suitable conditions for synthesizing ZSM-5 molecular sieves. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing ZSM-5 molecular sieves using catalytic cracking catalyst slag as raw material. This preparation method makes full use of the silicon and aluminum resources in the slag at a low cost to prepare ZSM-5 molecular sieves with high crystallinity and large specific surface area. This not only broadens the raw materials for preparing ZSM-5 molecular sieves, but also realizes the full resource utilization of slag and reduces the cost of preparing ZSM-5 molecular sieves.

[0006] This invention provides a method for preparing ZSM-5 molecular sieves using catalytic cracking catalyst residue as raw material, the specific scheme of which is as follows:

[0007] (1) Place the wet-based catalytic cracking catalyst residue in an oven and dry it at 100-130℃ until constant weight; place the dry-based residue in a muffle furnace and activate it at 450-700℃ for 2-6 hours to remove some impurities on the surface of the residue and activate the silicon and aluminum species in the residue; use it as a silicon and aluminum source for later use.

[0008] (2) According to a certain ratio of each component of the mother liquor for synthesizing ZSM-5 molecular sieve (including silicon source, aluminum source, sodium hydroxide, template agent and deionized water), dissolve sodium hydroxide in deionized water, add tetrapropylammonium hydroxide (TPAOH), stir for 10 minutes, then add silica sol, stir for about 1 hour, finally add slag, stir at room temperature for 4-10 hours, transfer to crystallization kettle, and place in an oven at 130-170℃ for crystallization for 38-82 hours; wherein, the ratio of each component of the mother liquor is SiO2:Al2O3:Na2O:TPAOH:H2O=17-32:1:1:2-7:400-800;

[0009] (3) After crystallization, the crystallized sieve is cooled to room temperature, filtered and washed, and dried at 110°C to obtain ZSM-5 molecular sieve.

[0010] The dry-based adhesive residue, based on a total mass of 100%, contains 5%-20% Al (calculated as Al2O3) and 45%-70% Si (calculated as SiO2).

[0011] As a further preferred embodiment of the present invention, based on the total mass of the dry-based adhesive residue as 100%, the mass content of Al in the dry-based adhesive residue, calculated as Al2O3, is 15%-20%, the mass content of Si in the dry-based adhesive residue, calculated as SiO2, is 45%-60%, the mass content of Na in the dry-based adhesive residue, calculated as NaO2, is 5%-10%, and the remainder is rare earth metal oxides and impurities.

[0012] As a further preferred embodiment of the present invention, the component ratio of the mother liquor is SiO2:Al2O3:Na2O:TPAOH:H2O = 22-32:1:1:2-7:700-800.

[0013] As a further preferred embodiment of the present invention, the crystallization temperature is 170℃-180℃; the crystallization time is 69-82 hours.

[0014] The beneficial effects of this invention are:

[0015] 1. This invention directly synthesizes ZSM-5 molecular sieves using catalytic cracking catalyst residue as raw material. Only high-temperature activation treatment of the residue is required. The preparation process is simple, easy to operate, and easy to industrialize.

[0016] 2. This invention fully utilizes the silicon and aluminum in the resin residue as silicon and aluminum sources for the synthesis of ZSM-5 molecular sieves. This reduces the synthesis cost of ZSM-5 molecular sieves and provides an effective way to efficiently utilize resin residue solid waste.

[0017] 3. This invention achieves the synthesis of low silica-alumina ratio zeolite ZSM-5 using only one template agent, tetrapropylammonium hydroxide.

[0018] 4. The ZSM-5 molecular sieve synthesized in this invention has high crystallinity and large specific surface area, and has good application prospects. Attached image description:

[0019] Figure 1 The XRD pattern of the product synthesized in Example 1 of this invention;

[0020] Figure 2 The XRD pattern of the product synthesized in Example 3 of this invention;

[0021] Figure 3 The XRD pattern of the product synthesized in Example 6 of this invention;

[0022] Figure 4 The XRD pattern of the product synthesized in Example 9 of this invention;

[0023] Figure 5 This is a SEM image of the product synthesized in Example 1 of the present invention. Detailed Implementation

[0024] The present invention will be further described through the following specific embodiments and in conjunction with the accompanying drawings. However, the scope of protection of the present invention is not limited to the following embodiments.

[0025] The composition analysis of the adhesive residue used in the specific embodiments of the present invention is as follows:

[0026] The wet-based rubber residue was placed in an oven and dried at 120℃ for 48 hours to remove a large amount of moisture, resulting in dry-based rubber residue. The main components of the rubber residue were analyzed by X-ray fluorescence spectroscopy. The mass fraction of oxides in the rubber residue was 51.07% SiO2, 18.92% Al2O3, 5.83% Na2O, 6.48% La2O3, 9.64% CeO2, 0.41% Fe2O3, 2.63% CaO, and 0.78% MgO. The remaining impurities accounted for less than 5% and could be ignored.

[0027] Example 1

[0028] (1) Dry the rubber residue in an oven at 130°C until constant weight to obtain dry rubber residue, and then activate it in a muffle furnace at 550°C for 3 hours.

[0029] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:800, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 26.64g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0030] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0031] Example 2

[0032] (1) Dry the rubber residue in an oven at 130°C until constant weight is obtained, and then activate it in a muffle furnace at 700°C for 2 hours.

[0033] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:800, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 26.64g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0034] (3) After stirring at room temperature, place the crystallizing agent in an oven at 170°C for 38 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0035] Example 3

[0036] (1) Dry the rubber residue in an oven at 100°C until constant weight is obtained, and then activate it in a muffle furnace at 550°C for 3 hours.

[0037] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=27:1:1:6:800, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 29.19g of deionized water are added and stirred for about 20 minutes. Then, 18.97g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0038] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0039] Example 4

[0040] (1) Same as step (1) in Example 1;

[0041] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=22:1:1:6:800, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 31.73g of deionized water are added and stirred for about 20 minutes. Then, 14.74g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0042] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0043] Example 5

[0044] (1) Dry the glue residue in an oven at 130°C until constant weight, and activate it in a muffle furnace at 450°C for 6 hours;

[0045] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=17:1:1:6:800, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 36.81g of deionized water are added and stirred for about 20 minutes. Then, 6.26g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0046] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0047] Example 6

[0048] (1) Same as step (1) in Example 1;

[0049] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:800, first, 0.2103g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 26.64g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0050] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 69 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0051] Example 7

[0052] (1) Same as step (1) in Example 1;

[0053] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:500, first, 0.2103g of sodium hydroxide and 10g of deionized water are stirred thoroughly until completely dissolved. Then, 27.54g of TPAOH (tetrapropylammonium hydroxide) solution and 6.09g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0054] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0055] Example 8

[0056] (1) Same as step (1) in Example 1;

[0057] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:700, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 16.49g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0058] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0059] Example 9

[0060] (1) Same as step (1) in Example 1;

[0061] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:2:800, first, 0.21g of sodium hydroxide and 30g of deionized water are stirred thoroughly until completely dissolved. Then, 9.18g of TPAOH (tetrapropylammonium hydroxide) solution and 30.41g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0062] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0063] Example 10

[0064] (1) Same as step (1) in Example 1;

[0065] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:4:800, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 18.35g of TPAOH (tetrapropylammonium hydroxide) solution and 33.53g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0066] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0067] Example 11

[0068] (1) Same as step (1) in Example 1;

[0069] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:800, first, 0.2103g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 26.64g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0070] (3) After stirring at room temperature, place the crystallizing agent in a 130℃ oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110℃ to obtain the solid product.

[0071] Example 12

[0072] (1) Same as step (1) in Example 1;

[0073] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:800, first, 0.2103g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 26.64g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0074] (3) After stirring at room temperature, place the crystallizing agent in a 150°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0075] Example 13

[0076] (1) Same as step (1) in Example 1;

[0077] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:6:800, first, 0.2103g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 27.53g of TPAOH (tetrapropylammonium hydroxide) solution and 26.64g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0078] 3) After stirring at room temperature, place the crystallizing agent in a 180℃ oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110℃ to obtain the solid product.

[0079] Example 14

[0080] (1) Same as step (1) in Example 1;

[0081] (2) At room temperature, according to SiO2:Na2O:Al2O3:TPAOH:H2O=32:1:1:7:800, first, 0.21g of sodium hydroxide and 20g of deionized water are stirred thoroughly until completely dissolved. Then, 32.11g of TPAOH (tetrapropylammonium hydroxide) solution and 26.64g of deionized water are added and stirred for about 20 minutes. Then, 23.21g of silica sol is added and stirred vigorously for at least half an hour. Finally, 3g of slag is added and stirred at room temperature for 7 hours until the mixture is uniform.

[0082] (3) After stirring at room temperature, place the crystallizing agent in a 170°C oven for 82 hours to crystallize. After crystallization, filter, wash, and dry at 110°C to obtain the solid product.

[0083] The crystallinity calculation refers to the crystallinity calculation formula in Huang Jiwu's "X-ray Diffraction of Polycrystalline Materials: Experimental Principles, Methods and Applications": Crystallinity, I c : Represents the integral intensity of the diffraction peak of the crystallization peak, I a (Represents the integral intensity of non-crystalline peak diffraction)

[0084] The pore structure parameters of the product were analyzed using an ASAP2020 physical adsorption analyzer. Pretreatment conditions included drying at 120℃ for 2 hours, followed by holding at 250℃ for 2 hours. The adsorbed gas was N2. Static volumetric method based on isothermal physical adsorption and capillary condensation theory were employed, with tests conducted in a liquid nitrogen environment at -196℃. The specific surface area of ​​the product was calculated using the Brunner-Emmet-Teller (BET) model, and the pore volume was calculated using the t-plot method.

[0085] Table 1. Crystallinity, specific surface area, and pore volume of ZSM-5 molecular sieves synthesized in each embodiment.

[0086] Example Crystallinity <![CDATA[Specific surface area / m 2 / g]]> <![CDATA[Pore volume / cm 3 / g]]> 1 91％ 285 0.1732 2 60％ 183 0.1401 3 76％ 275 0.1652 4 65％ 243 0.1622 5 33％ 186 0.1424 6 76％ 215 0.1618 7 63％ 195 0.1501 8 79％ 221 0.1648 9 65％ 200 0.1605 10 70％ 199 0.1598 11 66％ 191 0.1589 12 80％ 203 0.1601 13 89％ 280 0.1715 14 87％ 214 0.1579 15 74％ 272 0.1650

[0087] Figure 1 , 2 XRD patterns of the products obtained in Examples 1, 3, 6, and 9 are respectively. Figure 5The image shown is a SEM image of the product obtained in Example 1. XRD results indicate that ZSM-5 molecular sieve was synthesized using slag. Characteristic diffraction peaks of ZSM-5 molecular sieve appeared at 2θ = 7.870, 8.791, 23.157, 23.949, and 24.405, corresponding to crystal planes (101), (200), (332), (303), and (133), respectively. The SEM image shows that this is a spherical aggregate composed of many cubic small crystallites, which is a common morphology of ZSM-5 molecular sieve reported in the literature.

[0088] The synthesis of low-silicon-alumina ratio zeolite ZSM-5 is often difficult. Excessive aluminum content leads to premature hydrolysis of the precursor, resulting in high gel concentration and the formation of heteromorphic or amorphous SiO2 in the product. We successfully synthesized ZSM-5 molecular sieves using a template agent method, with catalytic cracking catalyst residue as raw material and tetrapropylammonium hydroxide as the template agent, achieving a silicon-alumina ratio in the range of 17-32. Except for Example 5, where the silicon-alumina ratio was 17, resulting in ZSM-5 with lower crystallinity, the crystallinity of other products was above 60%, and the specific surface area reached 200 m². 2 Approximately 0.5 g / g, with a pore volume of 0.16 cm³. 3 Approximately / g. Among them, the ZSM-5 molecular sieve prepared under the conditions of Example 1 had the highest crystallinity, reaching 91%.

[0089] Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this invention. The technical scope of this invention is not limited to the contents of the specification; it must be determined according to the scope of the claims.

Claims

1. A method for preparing ZSM-5 molecular sieves using catalytic cracking catalyst residue as raw material, characterized in that, The specific steps include the following: (1) The wet-based catalytic cracking slag is dried in an oven until constant weight to obtain dry-based slag; the dry-based slag is based on a total mass of 100%, wherein the mass content of Al is 5%-20% based on Al2O3 and the mass content of Si is 45%-70% based on SiO2; the dry-based slag is subjected to high-temperature activation treatment; the high-temperature activation is activated at 550℃ for 3h; (2) According to the proportion of each component of the ZSM-5 molecular sieve synthesis mother liquor, dissolve sodium hydroxide in deionized water, add the template agent tetrapropylammonium hydroxide (TPAOH), stir evenly, add silica sol to adjust the silicon-aluminum ratio, stir evenly again, add the slag after the high temperature activation treatment in step (1), stir at room temperature for 4-10 hours to carry out the crystallization reaction, the crystallization temperature is 170-180℃, and the crystallization time is 69-82 hours; wherein, the proportion of each component of the mother liquor is SiO2:Al2O3:Na2O:TPAOH:H2O=22-32:1:1:2-7:700-800; (3) After crystallization, cool, filter, wash until pH is neutral, and dry to obtain ZSM-5 molecular sieve.

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