A zsm-22 and zsm-5 composite molecular sieve, its preparation method and application
By controlling the preparation method of ZSM-22 and ZSM-5 composite molecular sieves, the problems of complex template agents and high cost were solved, and the molecular sieve ratio was controlled at low cost, thus expanding its application in industrial catalysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NAT PETROLEUM CORP
- Filing Date
- 2025-01-08
- Publication Date
- 2026-07-10
AI Technical Summary
Existing methods for synthesizing ZSM-22 and ZSM-5 composite molecular sieves suffer from complex template agents, high costs, and difficulty in controlling the proportions of different molecular sieves, failing to meet the needs of industrial production.
ZSM-22/ZSM-5 composite molecular sieves were prepared by mixing template agent, silicon source, aluminum source, water and alkali source in a specific molar ratio and adding seed crystals, followed by dynamic crystallization and calcination. The proportion of each molecular sieve was controlled, and the final product was optimized by ion exchange and drying calcination.
It has been achieved that the proportion of ZSM-5 molecular sieve can be adjusted in the range of 30%-70% at low cost, which simplifies the synthesis process and broadens the application prospects.
Smart Images
Figure CN122355306A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of molecular sieve preparation technology, specifically to a ZSM-22 and ZSM-5 composite molecular sieve, its preparation method, and its application. Background Technology
[0002] Molecular sieves, as important materials for ion exchange, adsorption separation, and catalysis, are widely used in industrial production. Based on their dimensionality, molecular sieves can be classified into one-dimensional, two-dimensional, and three-dimensional molecular sieves. Different dimensions of molecular sieves exhibit different catalytic properties. For example, in the MTO reaction, when the three-dimensional molecular sieve ZSM-5 (MFI topology) is used as a catalyst, the catalyst exhibits strong resistance to coking and a high content of aromatics in the product. Conversely, when the one-dimensional molecular sieve ZSM-22 (TON topology) is used as a catalyst, the catalyst is easily deactivated by coking, resulting in a high content of olefins in the product. In the isomerization reaction of long alkanes, when the one-dimensional molecular sieve SAPO-11 is used as an acidic support, the selectivity of isomer products is high; when the three-dimensional molecular sieve ZSM-5 is used as an acidic support, short-chain products are more abundant, and the selectivity of isomer products is low.
[0003] Composite molecular sieves are composite materials possessing the structural characteristics of two or more different molecular sieves. While maintaining the unique properties of each molecular sieve structure, composite molecular sieves also exhibit unique pore structures and acid properties due to the interactions between different structures, displaying properties different from those of single molecular sieves, thus making them promising for a wide range of applications.
[0004] The coexistence of molecular sieves of different dimensions to form composite molecular sieves can leverage the synergistic catalytic effects between different molecular sieves, better handle complex components, and overcome the limitations of single molecular sieve applications. In the synthesis of ZSM-22 molecular sieves, ZSM-5 molecular sieves often exist in the form of impurity crystals, thus easily forming a composite material of one-dimensional and three-dimensional molecular sieves.
[0005] Although ZSM-22 and ZSM-5 can easily form composite molecular sieves, current synthetic methods, as described in the comparative literature, still have many shortcomings, such as: the use of complex and costly template agents, and the inability to arbitrarily control the proportion of different molecular sieves in the composite molecular sieve. Therefore, developing low-cost, tunable composite molecular sieves suitable for industrial production faces significant challenges. Summary of the Invention
[0006] To address the aforementioned technical problems, the present invention aims to provide a ZSM-22 and ZSM-5 composite molecular sieve, its preparation method, and its application.
[0007] To achieve the above objectives, the present invention provides a method for preparing a ZSM-22 and ZSM-5 composite molecular sieve, comprising:
[0008] The template agent, silicon source, aluminum source, water, and alkali source are mixed in a molar ratio of (0.1-0.3):1:(0.011-0.017):(30-40):(0.089-0.44), and seed crystals are added to obtain a gel; wherein the silicon source is based on the molar amount of SiO2, the aluminum source on the molar amount of Al2O3, and the alkali source on the molar amount of OH-. - Molarity meter;
[0009] The gel is aged, then crystallized, and the crystallized product is calcined to obtain a composite molecular sieve; wherein the seed crystal is a ZSM-22 molecular sieve or a combination of ZSM-22 molecular sieve and ZSM-5 molecular sieve in a mass ratio of 1:4-1:1, and the amount of seed crystal is 2-8% of the mass of silicon source based on SiO2, preferably 4%.
[0010] In this invention, the composition of the raw material slurry affects the type and proportion of the topological structure contained in the synthesized composite molecular sieve. The gel formed by using the molar ratio of each raw material in this invention can obtain ZSM-22 / ZSM-5 composite molecular sieve.
[0011] In the above-mentioned preparation method of ZSM-22 and ZSM-5 composite molecular sieve, preferably, the crystallization is carried out by dynamic crystallization, with a stirring speed of 100-400 rpm, a crystallization temperature of 140-160℃, and a crystallization time of 36-72 h.
[0012] This invention provides a method for preparing a composite molecular sieve material consisting of one-dimensional and three-dimensional molecular sieves. The composite material is formed by the co-existence of one-dimensional molecular sieve ZSM-22 and three-dimensional molecular sieve ZSM-5, denoted as ZSM-22 / ZSM-5. The ZSM-22 / ZSM-5 composite molecular sieve of this invention has a TON and MFI topology.
[0013] In this invention, the crystallization process also affects the proportion of each type of molecular sieve in the final product. This invention uses dynamic crystallization to precisely control the proportion of each molecular sieve.
[0014] In the above-mentioned method for preparing ZSM-22 and ZSM-5 composite molecular sieves, preferably, the template agent is 1,6-hexanediamine (HDA).
[0015] In the above-mentioned method for preparing ZSM-22 and ZSM-5 composite molecular sieves, preferably, the silicon source includes one or more of coarse-porous silica gel, silica sol, and fumed silica.
[0016] In the above-mentioned method for preparing ZSM-22 and ZSM-5 composite molecular sieves, preferably, the aluminum source includes one or more of aluminum sulfate, sodium aluminate, and boehmite.
[0017] In the above-mentioned method for preparing ZSM-22 and ZSM-5 composite molecular sieves, preferably, the alkali source includes one or more of ammonia, sodium hydroxide and potassium hydroxide.
[0018] In the above-mentioned preparation method of ZSM-22 and ZSM-5 composite molecular sieve, preferably, the aging time is 1-4 hours and the aging temperature is 25-80℃; more preferably, the aging time is 4 hours and the aging temperature is 36℃.
[0019] In the above-mentioned method for preparing ZSM-22 and ZSM-5 composite molecular sieves, preferably, the calcination temperature is 550-600℃ and the calcination time is 6-24; more preferably, the rate of heating to the calcination temperature is 2-4℃ / min.
[0020] In the above-mentioned preparation method of ZSM-22 and ZSM-5 composite molecular sieve, preferably, the preparation method further includes: ion exchange of the calcined product with ammonium chloride solution to obtain the composite molecular sieve; the ion exchange temperature is 80-95℃ and the ion exchange time is 1-4h.
[0021] In the above-mentioned preparation method of ZSM-22 and ZSM-5 composite molecular sieve, preferably, the processing steps after obtaining the crystallized product include: filtering or centrifuging the crystallized product, washing it with deionized water until the pH of the product eluent is 7-8; then drying it in an oven at 60-120℃ for 8-12 hours; then heating it in a muffle furnace at a rate of 2-4℃ / min to 550-600℃ and calcining it for 6-24 hours to remove the organic template agent; finally exchanging it with a 1mol / L ammonium chloride solution at 80℃ for 3 hours, then filtering or centrifuging the product, drying it, calcining it, repeating this process three times to finally obtain the target product.
[0022] The present invention also provides a ZSM-22 and ZSM-5 composite molecular sieve, which is obtained by the above-mentioned preparation method of ZSM-22 and ZSM-5 composite molecular sieve.
[0023] This invention also provides an application of ZSM-22 and ZSM-5 composite molecular sieves in the catalytic preparation of olefins from methanol.
[0024] The technical solution provided by this invention has the following beneficial effects:
[0025] This invention can synthesize composite molecular sieves by modifying the gel composition (such as template agent, water content, alkalinity, and alkali source) and selecting seed crystals. The proportion of ZSM-5 molecular sieve in the composite molecular sieve can be controlled within the range of 30%-70%. The control method is simple, low-cost, has a wide range of modulation, and has broad application prospects. Attached Figure Description
[0026] Figure 1The XRD pattern of the molecular sieve in Example 1;
[0027] Figure 2 This is a SEM image of the molecular sieve from Example 1;
[0028] Figure 3 The XRD pattern of the molecular sieve in Example 2;
[0029] Figure 4 This is a SEM image of the molecular sieve from Example 2;
[0030] Figure 5 The XRD pattern of the molecular sieve in Example 3;
[0031] Figure 6 This is a SEM image of the molecular sieve from Example 3;
[0032] Figure 7 The XRD pattern of the molecular sieve in Example 4 is shown.
[0033] Figure 8 Here is a SEM image of the molecular sieve from Example 4;
[0034] Figure 9 The XRD pattern of the molecular sieve in Example 5;
[0035] Figure 10 This is a SEM image of the molecular sieve from Example 5;
[0036] Figure 11 The XRD pattern of the molecular sieve in Example 6;
[0037] Figure 12 Here is a SEM image of the molecular sieve from Example 6;
[0038] Figure 13 The XRD pattern of the molecular sieve in Example 7;
[0039] Figure 14 Here is a SEM image of the molecular sieve from Example 7;
[0040] Figure 15 The XRD pattern of the molecular sieve in Example 8;
[0041] Figure 16 Here is a SEM image of the molecular sieve from Example 8;
[0042] Figure 17 The XRD pattern of the molecular sieve in Example 9;
[0043] Figure 18 This is a SEM image of the molecular sieve from Example 9;
[0044] Figure 19 The XRD pattern of the molecular sieve in Comparative Example 1 is shown.
[0045] Figure 20 The image shows the SEM image of the molecular sieve in Comparative Example 1.
[0046] Figure 21 The XRD pattern of the molecular sieve in Comparative Example 2 is shown.
[0047] Figure 22 The image shows the SEM image of the molecular sieve in Comparative Example 2. Detailed Implementation
[0048] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.
[0049] Example 1: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 30%) from a single alkali source
[0050] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0051] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.3:1:0.011:40:0.222, with ZSM-22 molecular sieve as the seed crystal, and the amount added was 4% of the mass of silicon dioxide.
[0052] First, add 1.247g of KOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.74g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.24g of ZSM-22 molecular sieve seed crystals and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0053] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 100 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0054] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0055] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 1 As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0056] The sample was subjected to SEM testing (see...) Figure 2 The data showed that the sample contained both typical rod-shaped ZSM-22 molecular sieves and block-shaped ZSM-5 molecular sieves, which intertwined and grew together.
[0057] Example 2: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 50%) using a single alkali source
[0058] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0059] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.3:1:0.011:40:0.278, with ZSM-22 molecular sieve as the seed crystal, and the amount added was 4% of the mass of silicon dioxide.
[0060] First, add 1.558g of KOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.74g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.240g of ZSM-22 molecular sieve seed crystals and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0061] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 100 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0062] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0063] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 3 As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0064] The sample was subjected to SEM testing (see...) Figure 4 The results showed that the sample contained both typical rod-shaped ZSM-22 molecular sieves and blocky ZSM-5 molecular sieves, which interpenetrated and grew together, with a significant increase in the number of blocky crystals.
[0065] Compared with Example 1, it can be seen that increasing alkalinity is beneficial to increasing the proportion of ZSM-5 molecular sieve in the composite molecular sieve.
[0066] Example 3: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 70%) using a single alkali source
[0067] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0068] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.1:1:0.011:30:0.44, with ZSM-22 molecular sieve as the seed crystal, and the amount added was 8% of the mass of silicon dioxide.
[0069] First, add 2.471g of KOH to 43.546g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.74g of aluminum sulfate octahydrate. After the mixed solution gradually becomes clear, gradually add 1.156g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.48g of ZSM-22 molecular sieve seed crystals and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0070] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 100 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0071] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen form ZSM-22 molecular sieve.
[0072] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 5 As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0073] The sample was subjected to SEM testing (see...) Figure 6 The results showed that the sample contained both typical rod-shaped ZSM-22 molecular sieves and blocky ZSM-5 molecular sieves, which interpenetrated and grew together, with a significant increase in the number of blocky crystals.
[0074] Compared with Examples 1 and 2, increasing the seed crystal amount to 8% and improving the alkalinity, while reducing the amount of template agent and water, can yield a composite molecular sieve with a higher ZSM-5 content.
[0075] Example 4: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 30%) using a mixed alkali source method
[0076] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0077] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH:NaOH=0.2:1:0.011:40:0.106:0.117, with ZSM-22 molecular sieve as the seed crystal, and the amount added was 4% of the mass of silicon dioxide.
[0078] First, add 0.592g of KOH and 0.467g of NaOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.74g of aluminum sulfate octadechydrate. After the mixed solution gradually becomes clear, gradually add 2.312g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.24g of ZSM-22 molecular sieve seed crystals and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0079] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0080] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0081] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 7 As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0082] The sample was subjected to SEM testing (see...) Figure 8 The results showed that the sample contained both typical short rod-shaped ZSM-22 molecular sieves and blocky ZSM-5 molecular sieves, with the ZSM-22 molecular sieves growing on top of the ZSM-5 molecular sieve crystals.
[0083] Compared with Example 1, it can be seen that, under the same conditions of adding OH, using a mixed alkali source can reduce the amount of template agent required to synthesize a composite molecular sieve with high ZSM-22 content. This is because after the introduction of NaOH, Na... + Compared to K + Ions have a structural guiding effect on the growth of ZSM-22 crystals.
[0084] Example 5: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 50%) using a mixed alkali source method
[0085] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0086] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH:NaOH=0.1:1:0.011:30:0.206:0.234, with ZSM-22 molecular sieve as the seed crystal, and the amount added was 4% of the mass of silicon dioxide.
[0087] First, add 1.219g of KOH and 0.934g of NaOH to 43.546g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.74g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 1.162g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.240g of ZSM-22 molecular sieve seed crystals and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0088] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0089] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0090] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 9As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0091] The sample was subjected to SEM testing (see...) Figure 10 The results showed that the sample contained both typical short rod-shaped ZSM-22 molecular sieves and blocky ZSM-5 molecular sieves. The ZSM-22 molecular sieves were grown attached to the ZSM-5 molecular sieve crystals, and the blocky crystals were significantly increased.
[0092] Compared with Example 4, it can be seen that increasing the amount of NaOH in the raw materials can further reduce the amount of template agent. At the same time, the ZSM-5 content in the composite molecular sieve is increased, which verifies the result found in Example 2 that increasing alkalinity is beneficial to increasing the ZSM-5 zeolite content.
[0093] Meanwhile, comparing with Example 3, it can be seen that Na + The introduction of this agent is beneficial to the formation of ZSM-22 molecular sieves. This indicates that the molecular sieve content in the product can be adjusted by controlling the amount and weight of the alkali, thereby increasing the ZSM-22 molecular sieve content while reducing the amount of template agent.
[0094] Example 6: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 70%) using a mixed alkali source method
[0095] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0096] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH:NaOH=0.3:1:0.011:40:0.089:0.133, with ZSM-22 molecular sieve as the seed crystal, and the amount added was 2% of the mass of silicon dioxide.
[0097] First, add 0.499g of KOH and 0.533g of NaOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.74g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.12g of ZSM-22 molecular sieve seed crystals and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0098] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0099] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0100] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 11 As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0101] The sample was subjected to SEM testing (see...) Figure 12 The results showed that the sample contained both typical short rod-shaped ZSM-22 molecular sieves and blocky ZSM-5 molecular sieves. The ZSM-22 molecular sieves were grown attached to the ZSM-5 molecular sieve crystals, and the blocky crystals were more prominent.
[0102] Compared with Example 4, it can be seen that by reducing the amount of seed crystals and fine-tuning the ratio of NaOH and KOH, a composite molecular sieve with a higher ZSM-5 molecular sieve content can be obtained.
[0103] Example 7: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 30%) using a single alkali source mixed seed crystal method.
[0104] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0105] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.3:1:0.004:40:0.089, with the seed crystals being a 1:1 mass ratio mixture of ZSM-22 and ZSM-5 molecular sieves, and the amount added was 4% of the mass of silica.
[0106] First, add 0.499g of KOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.278g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.120g of ZSM-22 molecular sieve and 0.120g of ZSM-5 molecular sieve and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0107] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0108] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The supernatant is washed with deionized water until the pH value is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is exchanged with a 1 mol / L ammonium chloride solution at 95°C for 1 hour. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0109] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 13 As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0110] The sample was subjected to SEM testing (see...) Figure 14 The data showed that the sample contained both typical rod-shaped ZSM-22 molecular sieves and block-shaped ZSM-5 molecular sieves, which intertwined and grew together.
[0111] Compared to Example 1, this example uses a mixture of two molecular sieves as seed crystals, enabling the synthesis of composite molecular sieves at lower alkalinity, and further improving the silica-to-alumina ratio of the composite molecular sieve. The results of Examples 1-6 demonstrate that higher alkalinity is beneficial for the synthesis of ZSM-5 molecular sieves, while lower alkalinity is beneficial for the synthesis of ZSM-22. These results indicate that by introducing a mixed molecular sieve as seed crystals to synthesize composite molecular sieves, the content of various molecular sieves can be varied, and this can be achieved by changing the silica-to-alumina ratio in the feed.
[0112] Example 8: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 50%) by mixed seed crystal method
[0113] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0114] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.3:1:0.004:40:0.089, with the seed crystals being a mixture of ZSM-22 and ZSM-5 molecular sieves in a 1:2 mass ratio, and the amount added was 4% of the mass of silica.
[0115] First, add 0.499g of KOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.278g of aluminum sulfate octadechydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.080g of ZSM-22 molecular sieve and 0.160g of ZSM-5 molecular sieve and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0116] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0117] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The supernatant is washed with deionized water until the pH value is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is exchanged with a 1 mol / L ammonium chloride solution at 95°C for 1 hour. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0118] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 15 As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0119] The sample was subjected to SEM testing (see...) Figure 16 The data showed that the sample contained both typical rod-shaped ZSM-22 molecular sieves and block-shaped ZSM-5 molecular sieves, which intertwined and grew together.
[0120] Compared with Example 7, it can be seen that changing the content of ZSM-5 molecular sieve in the mixed molecular sieve seed crystals can adjust the content of the corresponding molecular sieve in the product.
[0121] Example 9: Synthesis of ZSM-22 / ZSM-5 composite zeolite (ZSM-5 content approximately 70%) via mixed seed crystal method
[0122] This embodiment provides a method for preparing a composite molecular sieve of ZSM-22 and ZSM-5, as detailed below:
[0123] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.3:1:0.004:40:0.089, with the seed crystals being a mixture of ZSM-22 and ZSM-5 molecular sieves in a 1:4 mass ratio, and the amount added was 4% of the mass of silica.
[0124] First, add 0.499g of KOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.278g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.040g of ZSM-22 molecular sieve and 0.200g of ZSM-5 molecular sieve and add them. Continue to stir vigorously for 4 hours for aging treatment.
[0125] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0126] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The supernatant is washed with deionized water until the pH value is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is exchanged with a 1 mol / L ammonium chloride solution at 95°C for 1 hour. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0127] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 17As shown, characteristic peaks of ZSM-22 molecular sieve are present at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, and characteristic peaks of ZSM-5 molecular sieve can be observed at 2θ = 7.92°, 8.80°, 23.26°, 23.92°, and 24.39°, proving that a ZSM-22 / ZSM-5 composite molecular sieve has been synthesized.
[0128] The sample was subjected to SEM testing (see...) Figure 18 The results showed that the sample contained both typical rod-shaped ZSM-22 molecular sieves and blocky ZSM-5 molecular sieves, which interpenetrated and grew together, with a significant increase in the number of blocky crystals.
[0129] Compared with Examples 7 and 8, it can be seen that changing the content of ZSM-5 molecular sieve in the mixed molecular sieve seed crystals can adjust the content of the corresponding molecular sieve in the product.
[0130] Comparative Example 1: Synthesis of Pure Phase ZSM-22 Molecular Sieves
[0131] This comparative example provides a method for preparing molecular sieves, as detailed below:
[0132] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.3:1:0.004:40:0.089, with ZSM-22 molecular sieve as the seed crystal, and the amount added was 4% of the mass of silicon dioxide.
[0133] First, add 0.499g of KOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.278g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.240g of ZSM-22 molecular sieve and add it. Continue to stir vigorously for 4 hours for aging treatment.
[0134] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0135] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0136] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 19 As shown, it exhibits characteristic peaks of ZSM-22 molecular sieve at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, with no other impurity crystal peaks, proving that a pure-phase ZSM-22 molecular sieve was synthesized.
[0137] The sample was subjected to SEM testing (see...) Figure 20 The results showed that the sample contained typical rod-shaped ZSM-22 molecular sieves.
[0138] Compared with Example 7, it can be found that at low alkalinity, the synthesis of composite molecular sieves requires mixed molecular sieves as seed crystals.
[0139] Comparative Example 2: Synthesis of Pure Phase ZSM-5 Molecular Sieves
[0140] This comparative example provides a method for preparing molecular sieves, as detailed below:
[0141] The gel was prepared in a 36°C water bath according to the following molar ratio: HDA:SiO2:Al2O3:H2O:KOH=0.3:1:0.004:40:0.089, with ZSM-5 molecular sieve as the seed crystal, and the amount added was 4% of the mass of silicon dioxide.
[0142] First, add 0.499g of KOH to 58.061g of pre-prepared deionized water and stir until the solid is completely dissolved. Then, gradually add 0.278g of aluminum sulfate octadecahydrate. After the mixed solution gradually becomes clear, gradually add 3.486g of 1,6-hexanediamine. Then, add 20.000g of silica sol and stir for 5 minutes to mix evenly. Finally, weigh out 0.240g of ZSM-5 molecular sieve and add it. Continue to stir vigorously for 4 hours for aging treatment.
[0143] After gel aging is complete, the material is transferred to a reactor with magnetic stirring function. After sealing the reactor, the stirring speed is set to 400 rpm and the reactor temperature is heated to 150°C. Crystallization is carried out under the above conditions for 48 hours.
[0144] After crystallization, the reaction vessel is cooled to room temperature, the reaction product is removed, and separated using conventional filtration or centrifugation. The product is washed with deionized water until the pH of the supernatant is 7-8. The solid product is then transferred to a 100°C oven and dried for 12 hours, followed by calcination in a muffle furnace at 600°C for 10 hours to remove the template agent. The product after template agent removal is then exchanged with a 1 mol / L ammonium chloride solution at 80°C for 3 hours. After cooling, the sample is removed and subjected to filtration, washing, drying, and calcination. The above process is repeated three times to obtain the hydrogen-form molecular sieve.
[0145] The sample was characterized by XRD, and the resulting spectrum is shown below. Figure 21 As shown, the sample exhibits characteristic peaks of ZSM-5 molecular sieve at 2θ = 8.15°, 20.34°, 24.34°, 24.60°, and 25.70°, with no other impurity peaks, confirming the synthesis of a pure-phase ZSM-5 molecular sieve. SEM analysis of the sample (see...) Figure 22 The results showed that the sample contained typical blocky ZSM-5 molecular sieves.
[0146] Compared with Example 7, it can be found that at low alkalinity, the synthesis of composite molecular sieves requires mixed molecular sieves as seed crystals. Furthermore, the experimental results of Examples 1-6, combined with Comparative Example 1, fully demonstrate that in the synthesis system of the ZSM-22 / ZSM-5 composite molecular sieve of the present invention, if ZSM-5 seed crystals are introduced, the product will be induced to generate pure ZSM-5 molecular sieves. Only by introducing seed crystals ZSM-22 or ZSM-22 / ZSM-5 can the generation of composite molecular sieves be achieved. Both types of seed crystals can affect the sample content in the composite molecular sieve product.
[0147] Experimental Example
[0148] This experimental example is used to evaluate the catalytic effect of the above-mentioned ZSM-22 and ZSM-5 composite molecular sieve in the methanol-to-olefins reaction.
[0149] The composite molecular sieves synthesized in Examples 1-7 were used in the methanol-to-olefins reaction, while the ZSM-22 molecular sieve, ZSM-5 molecular sieve, and a physical mixture of the two (mass ratio 1:1) synthesized in Comparative Examples 1 and 2 were used as comparisons.
[0150] The reaction conditions are as follows: 0.4 g catalyst, temperature 460 °C, methanol mass hourly space velocity (MHSV) 1 h⁻¹. -1。 The reaction results are shown in Table 1.
[0151] Table 1 Results of the methanol-to-olefins reaction
[0152]
[0153]
[0154] The results in the table above show that the composite molecular sieve catalyst exhibits significantly improved selectivity for low-carbon olefins compared to ZSM-22 molecular sieve, and a higher propylene to ethylene ratio in the reaction products compared to ZSM-5 molecular sieve. Compared to a physical mixture of the two molecular sieves, the composite molecular sieve catalyst of this invention demonstrates a clear advantage in uniform selectivity for low-carbon olefins, and a better propylene to ethylene ratio, fully illustrating the significant synergistic effect of the composite-grown zeolite, thereby improving catalyst performance.
[0155] Furthermore, a comparison of different embodiments shows that the ratio of propylene to ethylene can be controlled by adjusting the ratio of ZSM-22 and ZSM-5 molecular sieves in the composite molecular sieve. Therefore, this invention synthesizes a ZSM-22 / ZSM-5 composite molecular sieve that possesses the characteristics of both ZSM-22 and ZSM-5 molecular sieves, exhibiting excellent catalytic activity and product selectivity.
Claims
1. A method for preparing a ZSM-22 and ZSM-5 composite molecular sieve, comprising: The template agent, silicon source, aluminum source, water, and alkali source are mixed in a molar ratio of (0.1-0.3):1:(0.011-0.017):(30-40):(0.089-0.44), and seed crystals are added to obtain a gel; wherein the silicon source is based on the molar amount of SiO2, the aluminum source on the molar amount of Al2O3, and the alkali source on the molar amount of OH-. - Molarity meter; The gel is aged, then crystallized, and the crystallized product is calcined to obtain a composite molecular sieve; wherein the seed crystal is a ZSM-22 molecular sieve or a combination of ZSM-22 molecular sieve and ZSM-5 molecular sieve in a mass ratio of 1:4-1:1, and the amount of seed crystal is 2-8% of the mass of silicon source based on SiO2.
2. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The crystallization process employs dynamic crystallization, with a stirring speed of 100-400 rpm, a crystallization temperature of 140-160℃, and a crystallization time of 36-72 h.
3. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The template agent is 1,6-hexanediamine.
4. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The silicon source includes one or more of silica gel, silica sol, and fumed silica.
5. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The aluminum source includes one or more of aluminum sulfate, sodium aluminate, and boehmite.
6. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The alkaline source includes one or a combination of two or more of ammonia, sodium hydroxide, and potassium hydroxide.
7. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The aging time is 1-4 hours, and the aging temperature is 25-80℃.
8. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The roasting temperature is 550-600℃, and the roasting time is 6-24h.
9. The method for preparing the ZSM-22 and ZSM-5 composite molecular sieve according to claim 1, wherein, The preparation method further includes: ion exchange of the calcined product with an ammonium chloride solution to obtain the composite molecular sieve; the ion exchange temperature is 80-95℃ and the ion exchange time is 1-4h.
10. A ZSM-22 and ZSM-5 composite molecular sieve, which is obtained by the preparation method of the ZSM-22 and ZSM-5 composite molecular sieve according to any one of claims 1-9.
11. The application of the ZSM-22 and ZSM-5 composite molecular sieve according to claim 10 in the catalytic preparation of olefins from methanol.