ZSM-48 molecular sieve, its preparation method and application, hydrogen type ZSM-48 molecular sieve, its preparation method and application
By preparing nanosheet-like ZSM-48 molecular sieves and hydrogen-form ZSM-48 molecular sieves, the problem of poor catalytic performance caused by high mass transfer diffusion resistance was solved, and better catalytic performance and stability were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-15
- Publication Date
- 2026-03-24
AI Technical Summary
The existing ZSM-48 molecular sieve has the problem of large mass transfer and diffusion resistance, which affects its catalytic performance, especially under high and low silicon-aluminum ratio conditions.
Nanosheet-like ZSM-48 molecular sieves were synthesized using a specific structure-directing agent and preparation method. The nanosheet morphology was formed by the aggregation of nanoparticles, and hydrogen-form ZSM-48 molecular sieves were prepared by ammonium exchange, thereby optimizing their pore structure and acid properties.
It improves the accessibility and catalytic performance of molecular sieves, especially showing good catalytic performance and stability in organic conversion reactions.
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Figure CN119143149B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of molecular sieve technology, specifically to a ZSM-48 molecular sieve and its preparation method and application, and a hydrogen-form ZSM-48 molecular sieve and its preparation method and application. Background Technology
[0002] ZSM-48 molecular sieves possess a one-dimensional channel structure with ten-membered ring pores, and are commonly used as catalysts in organic compound conversion reactions such as aromatic alkylation, isomerization, disproportionation, and methanol conversion. Currently, there are ZSM-48 molecular sieves with high silica-to-alumina ratios (typically above 100) and low silica-to-alumina ratios (e.g., 30), but both types currently exhibit poor catalytic performance.
[0003] Zhu et al. synthesized a highly crystalline, alumina-rich ZSM-48 molecular sieve via allyl dimethyl ammonium chloride (ATMA), which exhibited high activity in catalyzing the hydroisomerization of n-heptane. However, this method suffers from high costs and requires a large amount of structure-directing agent [Kake Zhu, and Xinggui Zhou et al., Ind. Eng. Chem. Res. 2020, 59, 11139-11148]. Furthermore, the molecular sieves synthesized by these methods suffer from high mass transfer and diffusion resistance, which affects their catalytic performance. Daou et al. reported the use of (C... 22 H 45 N + (CH3)2C6H 12 N + (CH3)2CH2C6H4CH2N + (CH3)2C6H 12 N + (CH3)2C 22 H 45 (Br) - )2(Cl - )2 A multi-level ZSM-48 molecular sieve with a silica-alumina ratio of 31 was synthesized, but the low crystallinity of the product and the existence of competing phases limited its application [T.Jean Daou, New J. Chem., 2018, 42, 4457]. Summary of the Invention
[0004] The purpose of this invention is to overcome the problems of high mass transfer and diffusion resistance of ZSM-48 molecular sieves in the prior art, which affects catalytic performance. This invention provides a ZSM-48 molecular sieve and its preparation method and application, as well as a hydrogen-form ZSM-48 molecular sieve and its preparation method and application. The molecular sieve has a nanosheet morphology and can be used as an adsorbent or a catalyst for the conversion of organic compounds, and has good molecular diffusion properties.
[0005] The first aspect of the present invention provides a nanosheet-like ZSM-48 molecular sieve, wherein the molecular sieve has a nanosheet-like morphology formed by the aggregation of nanoparticles, the length of the nanoparticles is not higher than 50 nm, and the length of the nanosheets is not higher than 1000 nm.
[0006] The second aspect of the present invention provides a method for preparing the ZSM-48 molecular sieve described in the first aspect, wherein the method comprises: heating and crystallizing a mixture of a silicon source, an aluminum source, a structure directing agent, and an alkali source raw material; wherein the structure directing agent is composed of structural unit a as shown in formula (1).
[0007]
[0008] In equation (1), X is a halogen or OH, and * represents a linking site.
[0009] The third aspect of the present invention provides the application of the ZSM-48 molecular sieve described in the first aspect of the present invention in adsorption treatment and / or organic compound conversion reactions.
[0010] The fourth aspect of the present invention provides a method for preparing hydrogen-form ZSM-48 molecular sieve, wherein the preparation method includes: subjecting the ZSM-48 molecular sieve described in the first aspect of the present invention to ammonium exchange and solid-liquid separation, followed by heat treatment to obtain the hydrogen-form ZSM-48 molecular sieve.
[0011] The fifth aspect of the present invention provides a hydrogen-form ZSM-48 molecular sieve prepared by the preparation method of the third aspect of the present invention.
[0012] The sixth aspect of the present invention provides the application of the hydrogen-form ZSM-48 molecular sieve described in the fifth aspect of the present invention in adsorption treatment and / or organic compound conversion reactions.
[0013] Compared with the prior art, the present invention has at least the following beneficial effects:
[0014] The ZSM-48 molecular sieve of the present invention has a nanosheet-like morphology formed by the aggregation of nanoparticles, a unique crystal morphology, good accessibility, and good catalytic performance for organic conversion reactions. Attached Figure Description
[0015] Figure 1 This is the X-ray diffraction pattern of the molecular sieve sample in Example 1;
[0016] Figure 2 These are SEM images of the molecular sieve sample in Example 1 at different magnifications;
[0017] Figure 3 This is the N2 physical adsorption diagram of the molecular sieve sample in Example 1;
[0018] Figure 4 This is the NH3-TPD diagram of the hydrogen-form ZSM-48 molecular sieve sample in Example 1;
[0019] Figure 5 This is the X-ray diffraction pattern of the molecular sieve sample in Example 2;
[0020] Figure 6 These are SEM images of the molecular sieve sample in Example 2 at different magnifications;
[0021] Figure 7 This is the X-ray diffraction pattern of the molecular sieve sample in Example 5;
[0022] Figure 8 These are SEM images of the molecular sieve sample in Example 5 at different magnifications;
[0023] Figure 9 This is a SEM image of the molecular sieve sample in Comparative Example 1. Detailed Implementation
[0024] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0025] The first aspect of the present invention provides a nanosheet-like ZSM-48 molecular sieve, wherein the molecular sieve has a nanosheet-like morphology formed by the aggregation of nanoparticles, the length of the nanoparticles is not higher than 50 nm, and the length of the nanosheets is not higher than 1000 nm.
[0026] In this invention, the ZSM-48 molecular sieve with a specific nanosheet morphology, wherein the length of the nanoparticles is no more than 50 nm and the length of the nanosheets is no more than 1000 nm, makes the ZSM-48 molecular sieve readily accessible and gives it good catalytic performance for organic conversion reactions.
[0027] According to the present invention, in some preferred embodiments, the length of the nanoparticles is 10-50 nm, for example, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm, preferably 15-45 nm. The molecular sieves of the aforementioned embodiments have lower diffusion resistance.
[0028] According to the present invention, in some embodiments, the molecular sieve has a nanosheet cross-shaped morphology. The molecular sieves of the aforementioned embodiments have better molecular diffusivity, adsorption capacity, and stability.
[0029] According to the present invention, in some embodiments, the nanosheets are elliptical nanosheets. The molecular sieves of the aforementioned embodiments have better short-axis structures and exhibit better catalytic performance and stability in organic conversion reactions.
[0030] According to the present invention, in some preferred embodiments, the length of the nanosheets is 300-900 nm, for example 300 nm, 370 nm, 400 nm, 430 nm, 460 nm, 510 nm, 550 nm, 600 nm, 620 nm, 650 nm, 700 nm, 750 nm, 800 nm, or 900 nm, preferably 300-800 nm. The molecular sieves of the foregoing embodiments have better molecular diffusivity and exhibit better catalytic performance when used in organic conversion reactions.
[0031] According to the present invention, in some preferred embodiments, the thickness of the nanosheets is 10-100 nm, for example 10 nm, 16 nm, 18 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm, preferably 10-80 nm. The molecular sieves of the aforementioned embodiments have better stability and molecular diffusivity.
[0032] According to the present invention, in some preferred embodiments, the width of the nanosheets is 200-800 nm, for example 200 nm, 250 nm, 280 nm, 300 nm, 320 nm, 360 nm, 400 nm, 440 nm, 460 nm, 490 nm, 530 nm, 600 nm, 700 nm, or 800 nm, preferably 200-700 nm. The molecular sieves of the foregoing embodiments have better molecular diffusivity and better catalytic performance in use.
[0033] According to the present invention, in some preferred embodiments, the aspect ratio of the nanosheets is 1-2, for example 1, 1.1, 1.2, 1.3, 1.4, 1.6, 1.7, 1.8, 1.9 or 2, preferably 1.1-1.9. The molecular sieves of the foregoing embodiments have lower diffusion resistance, resulting in better catalytic performance.
[0034] According to the present invention, in some preferred embodiments, the aspect ratio of the nanosheets is 5-30, for example 5, 8, 10, 15.7, 17, 23, 24, 25, 28 or 30, preferably 5-25. The molecular sieves of the foregoing embodiments have better molecular diffusivity and better catalytic performance in use.
[0035] According to the present invention, the silicon-to-aluminum ratio of the molecular sieve is not particularly limited as long as the purpose of the present invention can be achieved. In some embodiments, the SiO2 / Al2O3 molar ratio of the molecular sieve is 40-250, for example 40, 44, 47, 53, 56, 65, 79, 84, 100, 131, 160, 171, 195, 210, 240 or 250, preferably 50-240. The molecular sieve with the special morphology in the present invention has a wider silicon-to-aluminum ratio than described in the aforementioned embodiments, and the molecular sieve is more accessible.
[0036] According to the present invention, the specific surface area of the molecular sieve is not particularly limited as long as the present invention can be realized. In some embodiments, the total specific surface area of the molecular sieve is not less than 300 m². 2 / g. The molecular sieve with a special morphology in this invention has a wider total specific surface area than described in the aforementioned embodiments, and the aforementioned molecular sieve has better catalytic performance.
[0037] According to some preferred embodiments of the present invention, the total specific surface area of the molecular sieve is 300-500 m². 2 / gram, for example, 300 meters 2 / gram, 312 meters 2 / gram, 321 meters 2 / gram, 326 meters 2 / gram, 330 meters 2 / gram, 335 meters 2 / gram, 346 meters 2 / gram, 350 meters 2 / gram, 400 meters 2 / gram, 450 meters 2 / gram or 500 meters 2 / g. The molecular sieves described above have better accessibility and better catalytic performance in organic conversion reactions.
[0038] According to the present invention, in some embodiments, the external specific surface area of the molecular sieve is not less than 100 m². 2 / g. The molecular sieves of the aforementioned embodiments exhibit better catalytic performance.
[0039] According to some preferred embodiments of the present invention, the molecular sieve has an external specific surface area of 100-250 m². 2 / gram, for example, 100 meters 2 / gram, 120 meters 2 / gram, 146 meters 2 / gram, 150 meters 2 / gram, 156 meters 2 / gram, 159 meters 2 / gram, 162 meters 2 / gram, 174 meters 2 / gram, 177 meters 2 / gram, 180 meters 2 / gram, 190 meters 2 / gram, 200 meters 2 / gram, 210 meters 2 / gram, 220 meters 2 / gram, 240 meters 2 / gram or 250 meters 2 / g. The molecular sieves described in the above embodiments exhibit better catalytic performance and stability.
[0040] According to the present invention, the molecular sieve with a specific morphology has abundant mesopores. As long as the objective of the present invention is achieved, the total pore volume of the molecular sieve is not particularly limited. In some embodiments, the total pore volume of the molecular sieve is not less than 0.25 cm³. 3 / g. The molecular sieves described in the above embodiments have better adsorption and dispersibility.
[0041] According to some preferred embodiments of the present invention, the total pore volume of the molecular sieve is 0.25-0.6 cm. 3 / gram, for example, 0.25 cm 3 / gram, 0.3cm 3 / gram, 0.35cm 3 / gram, 0.37cm 3 / gram, 0.39cm 3 / gram, 0.4cm 3 / gram, 0.41cm 3 / gram, 0.42cm 3 / gram, 0.45cm 3 / gram, 0.5cm 3 / gram, 0.55cm 3 / gram, 0.6cm 3 / g. The molecular sieves of the aforementioned embodiments have abundant mesopores, and exhibit good catalytic performance when used for organic conversion reactions.
[0042] According to the present invention, there is no particular limitation on the micropore volume of the molecular sieve as long as the purpose of the present invention can be achieved. In some embodiments, the micropore volume of the molecular sieve is not less than 0.05 cm³. 3 / g. The molecular sieves described in the above embodiments have abundant mesopores, and exhibit good catalytic performance when used for organic conversion reactions.
[0043] According to some preferred embodiments of the present invention, the micropore volume of the molecular sieve is 0.05-0.2 cm. 3 / gram, for example, 0.05 cm 3 / gram, 0.06cm 3 / gram, 0.07cm 3 / gram, 0.08cm 3 / gram, 0.1cm 3 / gram, 0.12cm 3 / gram, 0.15cm 3 / gram, 0.18cm 3 / gram or 0.2cm 3 / g. The molecular sieves described in the above embodiments exhibit better catalytic performance in organic conversion reactions.
[0044] The second aspect of the present invention provides a method for preparing the ZSM-48 molecular sieve described in the first aspect, wherein the method comprises: heating and crystallizing a mixture of a silicon source, an aluminum source, a structure directing agent, and an alkali source raw material; wherein the structure directing agent is composed of structural unit a as shown in formula (1).
[0045]
[0046] In equation (1), X is a halogen or OH, and * represents a linking site.
[0047] In this invention, the ZSM-48 molecular sieve prepared using structural unit a as a structure-directing agent, as shown in formula (1), has a special morphology and high crystallinity, abundant mesopores and adjustable acid density. The molecular sieve has good accessibility and good catalytic performance in organic conversion reactions. The inventors speculate that: on the one hand, the methylene chain length in structural unit a can regulate the connectivity between micropores and mesopores in this invention; on the other hand, the positive charge density of cations in structural unit a can balance the negative charge of Al sites on the aluminum-rich molecular sieve framework. At the same time, the specific methylene chain length and side chain structure can change the positive charge density of cations in structural unit a, so that the molecular sieve has better accessibility and good catalytic performance in organic conversion reactions.
[0048] In this invention, the structure directing agent can exist in the form of a pure substance or in the form of a mixture. A "pure substance" refers to a structure directing agent composed of structure directing agents with the same degree of polymerization, while a "mixture" refers to a structure directing agent composed of structure directing agents with different degrees of polymerization. This invention does not impose any special restrictions on the composition of the structure directing agent. In this invention, the number of structural units a is expressed by the average degree of polymerization.
[0049] According to the present invention, in some embodiments, the average degree of polymerization of the structure-directing agent is 2-20, for example 2, 3, 3.2, 4, 5.3, 8, 10, 11.1, 12, 14, 16, 18 or 20, preferably 3-12. Using the foregoing embodiments, the prepared molecular sieve has high crystallinity, abundant mesopores, and tunable acid density.
[0050] In this invention, the mixture formed by the raw materials containing silicon source, aluminum source, structure directing agent and alkali source refers to the mixture obtained by mixing solvent (e.g. water) with raw materials such as silicon source, aluminum source, structure directing agent and alkali source; it can also be a mixture obtained by mixing raw materials such as silicon source, aluminum source, solution containing structure directing agent (e.g. solution obtained by mixing solvent water and structure directing agent), solution containing alkali source (e.g. solution obtained by mixing solvent water and alkali source), etc. The mixing method is conventional in the art, for example, stirring at room temperature for 12-36 hours.
[0051] According to the present invention, the amount of each raw material in the aqueous solution is not particularly limited as long as the purpose of the present invention can be achieved. In some embodiments, the silicon source is calculated as SiO2, the aluminum source as Al2O3, the structure directing agent as structural unit a, and the alkali source as cation. The molar ratio of the silicon source, aluminum source, structure directing agent, alkali source, and water in the mixture is 1:a:b:c:d, where a is 0.004-0.03, b is 0.03-0.1, c is 0.10-0.5, and d is 8-100. Using the aforementioned embodiments, the synthesized molecular sieve has a wide range of silicon-to-aluminum ratios.
[0052] According to the present invention, in some preferred embodiments, a is 0.004-0.025. Using the aforementioned embodiments, ZSM-48 molecular sieves with good polarity can be formed more effectively.
[0053] According to the present invention, in some preferred embodiments, b is 0.04-0.09. Using the aforementioned embodiments, ZSM-48 molecular sieves with specific morphologies can be formed more effectively, and the synthesized molecular sieves exhibit better catalytic performance.
[0054] According to the present invention, in some preferred embodiments, c is 0.15-0.45. Using the aforementioned embodiments can further promote crystallization and better form ZSM-48 molecular sieves.
[0055] According to the present invention, in some preferred embodiments, d is 10-90. The aforementioned embodiments can better facilitate the crystallization process.
[0056] According to the present invention, those skilled in the art will understand that a silicon source refers to a substance that provides silicon. As long as the purpose of the present invention can be achieved, there is no special limitation on the specific type of silicon source. In some embodiments, the silicon source is selected from at least one of tetraethyl orthosilicate, fumed silica, silica sol and silica.
[0057] According to the present invention, those skilled in the art will understand that an aluminum source refers to a substance that provides aluminum. As long as the purpose of the present invention can be achieved, the specific type of aluminum source is not particularly limited. In some embodiments, the aluminum source is selected from at least one of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum hydroxide, sodium aluminate, boehmite, and aluminum isopropoxide.
[0058] According to the present invention, those skilled in the art will understand that an alkali source refers to a substance that provides alkali metal elements. As long as the purpose of the present invention can be achieved, the specific type of alkali source is not particularly limited. In some embodiments, the alkali source is selected from at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide.
[0059] According to the present invention, the conditions for crystallization treatment are not limited as long as the purpose of the present invention can be achieved. In some embodiments, the conditions for crystallization treatment include: crystallization at 130-190°C for 2-14 days.
[0060] According to some preferred embodiments of the present invention, the crystallization treatment conditions include: crystallization at 140-180°C for 3-12 days.
[0061] According to the present invention, the crystallization treatment can be selected as static crystallization or dynamic crystallization (e.g., under stirring at 40-100 rpm) as needed.
[0062] According to the present invention, when preparing ZSM-48 molecular sieve, the post-treatment method can be selected as needed after crystallization treatment. In some embodiments, solid-liquid separation and heat treatment are performed after crystallization treatment.
[0063] According to the present invention, solid-liquid separation refers to obtaining a solid from a mixture obtained by crystallization by any conventionally known separation method. Examples of separation methods include filtration and washing. Filtration can be simple vacuum filtration or other filtration methods. Washing can be performed using deionized water and / or ethanol.
[0064] According to the present invention, in some embodiments, the heat treatment conditions include: drying followed by calcination.
[0065] According to the present invention, drying can be carried out in accordance with conventional drying methods in the art, such as drying at 40-250°C for 8-30 hours, preferably drying at 60-150°C for 10-20 hours, wherein the drying can be carried out under normal pressure or under reduced pressure.
[0066] According to the present invention, calcination can be carried out in any manner conventionally known in the art as long as the purpose of the present invention can be achieved. In some embodiments, the calcination conditions include a calcination temperature of 300-800°C, preferably 400-650°C.
[0067] According to the present invention, in some embodiments, the calcination conditions include: a calcination time of 1-10 hours, preferably 3-6 hours.
[0068] According to the present invention, in some embodiments, the calcination conditions include: being carried out in an oxygen-containing atmosphere.
[0069] In this invention, oxygen-containing atmosphere refers to air or oxygen atmosphere.
[0070] The third aspect of the present invention provides the application of the ZSM-48 molecular sieve described in the first aspect of the present invention in adsorption treatment and / or organic compound conversion reactions.
[0071] In this invention, the ZSM-48 molecular sieve with its special morphology has good accessibility and good catalytic performance for organic conversion reactions.
[0072] In this invention, the reactions involved in the organic compound conversion reaction generally include Fridel-Krawczy alkylation, isomerization, hydroisomerization, and hydrogenolysis.
[0073] In this invention, ZSM-48 molecular sieves can be used in any physical form, such as powder, granules, or molded into shapes (e.g., strips, clover shapes, etc.) by kneading with binders conventional in the art. These physical forms can be obtained in any manner known in the art, and this invention is not particularly limited in this regard; ZSM-48 molecular sieves can also be used after modification using conventional modification methods in the art, such as by ammonium exchange of molecular sieves to form hydrogen-form ZSM-48 molecular sieves.
[0074] The fourth aspect of the present invention provides a method for preparing hydrogen-form ZSM-48 molecular sieve, wherein the preparation method includes: subjecting the ZSM-48 molecular sieve described in the first aspect of the present invention to ammonium exchange and solid-liquid separation, followed by heat treatment to obtain the hydrogen-form ZSM-48 molecular sieve.
[0075] In this invention, the hydrogen-form ZSM-48 molecular sieve after ammonium exchange retains the unique morphology, surface area, and pore volume of the ZSM-48 molecular sieve. The only difference is the transformation of the ZSM-48 molecular sieve into a hydrogen-form ZSM-48 molecular sieve, resulting in a change in acidity. During the heat treatment process following ammonium exchange and solid-liquid separation, it is protonated (H₂O). + The hydrogen-form ZSM-48 molecular sieve prepared by the present invention replaces the alkali metal in ZSM-48 molecular sieve and has good catalytic and adsorption properties.
[0076] In this invention, ammonium exchange is a conventional operation method in the art, that is, ammonium exchange is performed using an aqueous solution of ammonium salt. The aqueous solution of ammonium salt can be selected as needed. For example, the ammonium salt is selected from at least one of ammonium chloride, ammonium nitrate, ammonium carbonate and ammonium sulfate. The concentration of ammonium ions in the aqueous solution of ammonium salt is 0.1-1 mol / L. The amount of ammonium salt aqueous solution can be selected as needed. For example, the solid-liquid ratio of ZSM-48 molecular sieve to ammonium salt aqueous solution is 1:(5-20) (mass ratio). The conditions for ammonium exchange can be selected as needed. For example, ion exchange is performed at 30-80℃ for 1-8 hours.
[0077] In this invention, those skilled in the art can select the number of times ammonium exchange and solid-liquid separation are performed as needed, for example, 1-3 times.
[0078] According to the present invention, in the preparation of hydrogen-type ZSM-48 molecular sieve, the heat treatment includes conventional drying and calcination steps in the art, such as overnight drying at 60-150°C (the overnight drying time is generally 8-15 hours) and calcination at 400-650°C for 3-6 hours in an oxygen-containing atmosphere (such as an air atmosphere or an oxygen atmosphere).
[0079] The fifth aspect of the present invention provides a hydrogen-form ZSM-48 molecular sieve prepared by the preparation method of the third aspect of the present invention.
[0080] In this invention, the hydrogen-form ZSM-48 molecular sieve has good adsorption properties and exhibits good catalytic performance when used in organic matter conversion reactions.
[0081] According to the present invention, in some embodiments, the total acid content of the hydrogen-form ZSM-48 molecular sieve is not less than 150 μmol / g. The molecular sieves of the aforementioned embodiments have better activity and catalytic performance.
[0082] According to some preferred embodiments of the present invention, the total acidity of the hydrogen-form ZSM-48 molecular sieve is 150-1000 μmol / g, for example, 150 μmol / g, 189 μmol / g, 250 μmol / g, 326 μmol / g, 400 μmol / g, 500 μmol / g, 575 μmol / g, 596 μmol / g, 686 μmol / g, 700 μmol / g, 724 μmol / g, 812 μmol / g, 900 μmol / g, or 1000 μmol / g. The molecular sieves of the aforementioned embodiments have good accessibility and exhibit good catalytic performance in organic matter conversion reactions.
[0083] According to the present invention, in some embodiments, the strong acid content of the hydrogen-form ZSM-48 molecular sieve is not less than 70 μmol / g. The molecular sieve of the aforementioned embodiments has better catalytic performance.
[0084] According to the present invention, in some preferred embodiments, the strong acid content of the molecular sieve is 70-500 μmol / g, for example, 70 μmol / g, 77 μmol / g, 84 μmol / g, 150 μmol / g, 186 μmol / g, 247 μmol / g, 261 μmol / g, 284 μmol / g, 308 μmol / g, 328 μmol / g, 400 μmol / g, or 500 μmol / g. The molecular sieves of the aforementioned embodiments have better catalytic activity.
[0085] According to the present invention, in some embodiments, the proportion of strong acid in the hydrogen-form ZSM-48 molecular sieve is not less than 25% of the total acid content. The molecular sieve of the aforementioned embodiments has good catalytic properties.
[0086] According to the present invention, in some preferred embodiments, the proportion of strong acid in the molecular sieve to the total acid content is 25-50%, for example, 25%, 26%, 31%, 32%, 38%, 39%, 41%, 43%, 45%, or 50%. The molecular sieve catalysts of the aforementioned embodiments exhibit good catalytic activity and good selectivity for the target product when used for compound conversion.
[0087] The sixth aspect of the present invention provides the application of the hydrogen-form ZSM-48 molecular sieve described in the fifth aspect of the present invention in adsorption treatment and / or organic compound conversion reactions.
[0088] In this invention, the structure of the nanosheet-like ZSM-48 molecular sieve is determined by X-ray diffraction (XRD), which is measured using an X-ray powder diffractometer. Before sample testing, the crystallization of the molecular sieve sample is observed using a scanning electron microscope (SEM) to confirm that the sample contains only one type of crystal, i.e., the molecular sieve sample is a pure phase. Based on this, XRD testing is then performed to ensure that there are no interfering peaks from other crystals in the diffraction peaks of the XRD pattern.
[0089] In this invention, the X-ray powder diffractometer used for analyzing the molecular sieve is a Rigaku D / MAX2550VB / PC model from Japan, and the CuKα ray source is used to analyze the phase composition of the sample. Nickel filter, 2θ scanning range 5-50°, operating voltage 40KV, current 40mA, scanning rate 10° / min.
[0090] In this invention, the scanning electron microscope (SEM) used for molecular sieves is a NOVA NanoSEM 450 field emission scanning electron microscope from FEI Corporation, USA. Using this SEM, the molecular sieves were observed at different magnifications. A random field of view was selected, and the length of the nanoparticles in that field of view was calculated. This operation was repeated 10 times, and the average of the sum of the 10 calculations was taken as the length of the nanoparticle. The average length of all nanosheets was also calculated and repeated 10 times, and the average of the sum of the 10 calculations was taken as the length of the nanosheets. The width and thickness of all nanosheets in the field of view were measured using the same method, and this operation was repeated 5 times. The length of the nanoparticle is its maximum outer diameter; the length of the nanosheet is its maximum outer diameter; the minimum diameter of the largest area section perpendicular to the nanosheet is its thickness, and the maximum diameter is its width.
[0091] In this invention, the total pore volume, micropore volume, total specific surface area, and external specific surface area of the molecular sieve are measured using the nitrogen physical adsorption-desorption method (BET method): the nitrogen physical adsorption-desorption isotherm of the molecular sieve is measured using a physical adsorption instrument (Beijing Best Instrument Technology Co., Ltd. 3H-2000PS4 model), and then calculated using the BET equation and t-plot equation. The experimental conditions for this molecular sieve are: measurement temperature -196℃, and before measurement, the molecular sieve is heat-treated at 550℃ in air atmosphere for 6 hours, and then pre-treated in vacuum at 350℃ for 4 hours.
[0092] In this invention, the SiO2 / Al2O3 molar ratio of the molecular sieve is tested using an inductively coupled plasma atomic emission spectrometer (ICP) (model Varian 710-ES). The content of elements in the sample is determined by dissolving it in hydrofluoric acid, and the results are expressed in molars.
[0093] In this invention, the acid content of the molecular sieve was determined using a Micrometer Chemisorb 2720 instrument to perform NH3-TPD chemical adsorption-desorption curve analysis. Before testing, the sample was activated at 550℃ for 1 hour, ammonia gas was adsorbed at 100℃ for 20 minutes, and then desorption was detected at 100-600℃. The peak area was quantified by quantitative cyclic pulse ammonia gas analysis, and the acid content corresponding to the desorption temperature above 300℃ was considered as the acid content of a strong acid by Gaussian distribution peak segmentation.
[0094] The present invention will be described in detail below through embodiments. The following embodiments:
[0095] The structure-directing agent is composed of structural unit a as shown in formula (1).
[0096]
[0097] In equation (1), * represents the connection site.
[0098] In the following examples and comparative examples:
[0099] The conditions for the hydroisomerization of n-heptane are as follows: catalyst loading of 0.4 g, particle size of 20-40 mesh, hydrogen to n-heptane molar ratio of 2:6, reaction temperature of 200-400 °C, and weight hourly space velocity of 1 h⁻¹. -1 The yield of the isomer is determined by measuring the reaction time and obtaining the highest yield of the isomer product.
[0100] Isomer yield % = (mass of isomers in the product) / (total mass of carbon-containing products) × 100%;
[0101] The isomer products are single-branched and double-branched alkane isomers, and the carbon-containing byproducts are mainly cracked products, excluding the feedstock n-heptane.
[0102] Example 1
[0103] A mixture was prepared by stirring 4.60 g of deionized water, 0.14 g of structure-directing agent (X is Br, average degree of polymerization 3.2), 0.08 g of aluminum nitrate nonahydrate, 0.09 g of sodium hydroxide, and 1.35 g of tetraethyl orthosilicate at room temperature for 24 hours. The final molar ratio of the mixture was:
[0104] SiO2 / Al2O3 = 61;
[0105] NaOH / SiO2 = 0.35;
[0106] SDA / SiO2 = 0.05;
[0107] H2O / SiO2 = 40;
[0108] The final mixture was placed in a stainless steel reactor and heated to crystallize for 5 days under static crystallization conditions at 150°C. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and calcined in air at 550°C for 6 hours to obtain the molecular sieve sample.
[0109] Figure 1 The X-ray diffraction pattern of the molecular sieve sample is obtained by... Figure 1 The molecular sieve sample obtained is ZSM-48 molecular sieve;
[0110] Figure 2 SEM images of molecular sieve samples at different magnifications were obtained by... Figure 2The molecular sieve sample can be obtained with an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and the specific nanosheets have an intersecting morphology. The length of the nanoparticles is 35 nm, the thickness of the nanosheets is 30 nm, the length is 700 nm, the width is 440 nm, the length-to-thickness ratio is 23.3, and the length-to-width ratio is 1.6.
[0111] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 47 using inductively coupled plasma atomic emission spectrometry (ICP).
[0112] The N2 physical adsorption diagram of the molecular sieve sample is as follows: Figure 3 As shown, the specific surface area of the molecular sieve is 330 m². 2 / gram, with an external specific surface area of 180 m² measured by the BET method. 2 / g; Total pore volume 0.41cm 3 / gram, micropore volume is 0.06 cm³ 3 / gram.
[0113] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0114] The NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve is shown below. Figure 4 As shown, the total acid content of the molecular sieve sample is 793 μmol / g, the strong acid content is 328 μmol / g, and the proportion of strong acid content to total acid content is 41%.
[0115] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 71%.
[0116] Example 2
[0117] A mixture was prepared by stirring 17.20 g of deionized water, 0.52 g of structure-directing agent (X is Br, average degree of polymerization 3.2), 0.32 g of sodium hydroxide, 0.18 g of aluminum nitrate nonahydrate, and 5.10 g of tetraethyl orthosilicate at room temperature for 24 hours. The final molar ratio of the mixture was:
[0118] SiO2 / Al2O3 = 102;
[0119] NaOH / SiO2 = 0.33;
[0120] SDA / SiO2 = 0.05;
[0121] H2O / SiO2 = 39;
[0122] The final mixture was placed in a stainless steel reactor and heated to crystallize at 170℃ (60 rpm) for 3 days. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100℃, and calcined in air at 550℃ for 6 hours to obtain the molecular sieve sample.
[0123] Figure 5 The X-ray diffraction pattern of the molecular sieve sample is obtained by... Figure 5 The molecular sieve sample obtained is ZSM-48 molecular sieve;
[0124] Figure 6 SEM images of molecular sieve samples at different magnifications were obtained by... Figure 6 The molecular sieve sample can be obtained with an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and the specific nanosheets have an intersecting morphology. The length of the nanoparticles is 40 nm, the thickness of the nanosheets is 25 nm, the length is 600 nm, the width is 490 nm, the length-to-thickness ratio is 24.0, and the length-to-width ratio is 1.2.
[0125] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 84 using inductively coupled plasma atomic emission spectrometry (ICP).
[0126] N2 physisorption diagram of molecular sieve samples and Figure 3 Similarly, the specific surface area of molecular sieves is 346 m². 2 / gram, with an external specific surface area of 174 m² measured by the BET method. 2 / g; Total pore volume 0.39cm 3 / gram, micropore volume is 0.07 cm³ 3 / gram.
[0127] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0128] NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve and Figure 4 Similarly, the total acid content of the molecular sieve sample was found to be 575 μmol / g, the strong acid content was 247 μmol / g, and the strong acid content accounted for 43% of the total acid content.
[0129] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 70%.
[0130] Example 3
[0131] A mixture was prepared by stirring 4.50 g of deionized water, 0.16 g of a structure-directing agent aqueous solution (X is OH, average degree of polymerization is 3.2, mass concentration is 60%), 0.08 g of sodium hydroxide, 0.08 g of aluminum nitrate nonahydrate, and 1.35 g of tetraethyl orthosilicate at room temperature for 24 hours. The final molar ratio of the mixture was:
[0132] SiO2 / Al2O3 = 61;
[0133] NaOH / SiO2 = 0.31;
[0134] SDA / SiO2 = 0.05;
[0135] H2O / SiO2 = 39;
[0136] The final mixture was placed in a stainless steel reactor and heated to crystallize for 6 days under static crystallization conditions at 150°C. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and calcined in air at 550°C for 6 hours to obtain the molecular sieve sample.
[0137] X-ray diffraction pattern of molecular sieve sample and Figure 1 Similarly, the molecular sieve sample can be identified as ZSM-48 molecular sieve;
[0138] SEM images of molecular sieve samples and Figure 2 Similarly, the molecular sieve sample can be obtained with an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and specifically the morphology of the intersecting nanosheets. The length of the nanoparticles is 25 nm, the thickness of the nanosheets is 35 nm, the length is 550 nm, the width is 300 nm, the length-to-thickness ratio is 15.7, and the length-to-width ratio is 1.8.
[0139] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 56 using inductively coupled plasma atomic emission spectrometry (ICP).
[0140] N2 physisorption diagram of molecular sieve samples and Figure 3 Similarly, the specific surface area of molecular sieves is 326 m². 2 / gram, with an external specific surface area of 177 m² measured by the BET method. 2 / g; Total pore volume 0.38cm3 / gram, micropore volume is 0.07 cm³ 3 / gram.
[0141] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0142] NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve and Figure 4 Similarly, the total acid content of the molecular sieve sample was found to be 686 μmol / g, the strong acid content was 261 μmol / g, and the strong acid content accounted for 38% of the total acid content.
[0143] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 70%.
[0144] Example 4
[0145] A mixture was prepared by stirring 5.20 g of deionized water, 0.25 g of a structure-directing agent aqueous solution (X is OH, average degree of polymerization is 5.3, mass concentration is 60%), 0.10 g of sodium hydroxide, 0.02 g of sodium aluminate, and 1.50 g of tetraethyl orthosilicate at room temperature for 24 hours. The final molar ratio of the mixture was:
[0146] SiO2 / Al2O3 = 59;
[0147] NaOH / SiO2 = 0.38;
[0148] SDA / SiO2 = 0.07;
[0149] H2O / SiO2 = 41;
[0150] The final mixture was placed in a stainless steel reactor and heated to crystallize at 160°C for 4 days under static crystallization conditions. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and calcined in air at 550°C for 6 hours to obtain the molecular sieve sample.
[0151] X-ray diffraction pattern of molecular sieve sample and Figure 1 Similarly, the molecular sieve sample can be identified as ZSM-48 molecular sieve;
[0152] SEM images of molecular sieve samples and Figure 2Similarly, the molecular sieve sample can be obtained with an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and specifically the morphology of the intersecting nanosheets. The length of the nanoparticles is 30 nm, the thickness of the nanosheets is 30 nm, the length is 510 nm, the width is 360 nm, the length-to-thickness ratio is 17.0, and the length-to-width ratio is 1.4.
[0153] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 53 using inductively coupled plasma atomic emission spectrometry (ICP).
[0154] N2 physisorption diagram of molecular sieve samples and Figure 3 Similarly, the specific surface area of molecular sieves is 335 m². 2 / gram, with an external specific surface area of 162 m² measured by the BET method. 2 / g; Total pore volume 0.35cm 3 / gram, micropore volume is 0.07 cm³ 3 / gram.
[0155] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0156] NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve and Figure 4 Similarly, the total acid content of the molecular sieve sample was found to be 724 μmol / g, the strong acid content was 284 μmol / g, and the strong acid content accounted for 39% of the total acid content.
[0157] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 66%.
[0158] Example 5
[0159] A mixture was prepared by stirring 9.20 g of deionized water, 0.28 g of structure-directing agent (X is Br, with an average degree of polymerization of 11.1), 0.048 g of aluminum nitrate nonahydrate, 0.18 g of sodium hydroxide, and 2.70 g of tetraethyl orthosilicate at room temperature for 24 hours. The final molar ratio of the mixture was:
[0160] SiO2 / Al2O3 = 203;
[0161] NaOH / SiO2 = 0.35;
[0162] SDA / SiO2 = 0.05;
[0163] H2O / SiO2 = 40;
[0164] The final mixture was placed in a stainless steel reactor and heated to crystallize at 145°C for 10 days under static crystallization conditions. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and then calcined in air at 550°C for 6 hours to obtain the molecular sieve sample.
[0165] X-ray diffraction pattern of molecular sieve sample as shown Figure 7 As shown, the molecular sieve sample can be identified as ZSM-48 molecular sieve.
[0166] SEM images of molecular sieve samples at different magnifications are shown below. Figure 8 As shown, the molecular sieve sample has an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and the specific nanosheets have an intersecting morphology. The nanoparticles have a length of 35 nm, a thickness of 35 nm, a length of 800 nm, a width of 460 nm, a length-to-thickness ratio of 22.9, and a length-to-width ratio of 1.7.
[0167] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 171 using inductively coupled plasma atomic emission spectrometry (ICP).
[0168] N2 physisorption diagram of molecular sieve samples and Figure 3 Similarly, the specific surface area of molecular sieves is 312 m². 2 / gram, with an external specific surface area of 156 m² measured by the BET method. 2 / g; Total pore volume 0.37cm 3 / gram, micropore volume is 0.07 cm³ 3 / gram.
[0169] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0170] NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve and Figure 4 Similarly, the total acid content of the molecular sieve sample was found to be 234 μmol / g, the strong acid content was 61 μmol / g, and the strong acid content accounted for 26% of the total acid content.
[0171] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹.-1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 59%.
[0172] Example 6
[0173] The method is the same as in Example 1, except that: 1.35 g of tetraethyl orthosilicate is replaced with silica sol (40% mass concentration), and the mass of the silica sol is controlled so that the molar ratio of the final mixture is:
[0174] SiO2 / Al2O3 = 61;
[0175] NaOH / SiO2 = 0.35;
[0176] SDA / SiO2 = 0.05;
[0177] H2O / SiO2 = 40;
[0178] The final mixture was placed in a stainless steel reactor and heated to crystallize for 5 days under static crystallization conditions at 150°C. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and calcined in air at 550°C for 6 hours to obtain the molecular sieve sample.
[0179] X-ray diffraction pattern of molecular sieve sample and Figure 1 Similarly, the molecular sieve sample can be identified as ZSM-48 molecular sieve;
[0180] SEM images of molecular sieve samples and Figure 2 Similarly, the molecular sieve sample can be obtained with an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and specifically the morphology of the intersecting nanosheets. The length of the nanoparticles is 40 nm, the thickness of the nanosheets is 18 nm, the length is 430 nm, the width is 320 nm, the length-to-thickness ratio is 23.9, and the length-to-width ratio is 1.3.
[0181] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 64 using inductively coupled plasma atomic emission spectrometry (ICP).
[0182] The N2 physical adsorption diagram of the molecular sieve sample is as follows: Figure 3 As shown, the specific surface area of the molecular sieve is 321 m². 2 / gram, with an external specific surface area of 159 m² measured by the BET method. 2 / g; Total pore volume 0.39cm 3 / gram, micropore volume is 0.07 cm³ 3 / gram.
[0183] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0184] NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve and Figure 4 Similarly, the total acid content of the molecular sieve sample was found to be 712 μmol / g, the strong acid content was 236 μmol / g, and the strong acid content accounted for 33% of the total acid content.
[0185] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 70%.
[0186] Example 7
[0187] The method is the same as in Example 4, except that 1.50 g of tetraethyl orthosilicate is replaced with silica, and the mass of silica is controlled so that the molar ratio of the final mixture is:
[0188] SiO2 / Al2O3 = 59;
[0189] NaOH / SiO2 = 0.36;
[0190] SDA / SiO2 = 0.07;
[0191] H2O / SiO2 = 41;
[0192] The final mixture was placed in a stainless steel reactor and heated to crystallize for 4 days under static crystallization conditions at 150°C. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and calcined in air at 550°C for 6 hours to obtain the molecular sieve sample.
[0193] X-ray diffraction pattern of molecular sieve sample and Figure 1 Similarly, the molecular sieve sample can be identified as ZSM-48 molecular sieve;
[0194] SEM images of molecular sieve samples and Figure 2 Similarly, the molecular sieve sample can be obtained with an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and specifically the morphology of the intersecting nanosheets. The length of the nanoparticles is 25 nm, the thickness of the nanosheets is 20 nm, the length is 460 nm, the width is 280 nm, the length-to-thickness ratio is 23.0, and the length-to-width ratio is 1.6.
[0195] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 65 using inductively coupled plasma atomic emission spectrometry (ICP).
[0196] N2 physisorption diagram of molecular sieve samples and Figure 3 Similarly, the specific surface area of molecular sieves is 346 m². 2 / gram, with an external specific surface area of 149 m² measured by the BET method. 2 / g; Total pore volume 0.40 cm³ 3 / gram, micropore volume is 0.08 cm³ 3 / gram.
[0197] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0198] NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve and Figure 4 Similarly, the total acid content of the molecular sieve sample was found to be 489 μmol / g, the strong acid content was 202 μmol / g, and the strong acid content accounted for 41% of the total acid content.
[0199] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 67%.
[0200] Example 8
[0201] The method is the same as in Example 4, except that: 0.10 g of sodium hydroxide is replaced with potassium hydroxide, and the mass of potassium hydroxide is controlled so that the molar ratio of the final mixture is:
[0202] SiO2 / Al2O3 = 59;
[0203] KOH / SiO2 = 0.36;
[0204] SDA / SiO2 = 0.07;
[0205] H2O / SiO2 = 41;
[0206] The final mixture was placed in a stainless steel reactor and heated to crystallize for 4 days under static crystallization conditions at 150°C. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and calcined in air at 550°C for 6 hours to obtain the molecular sieve sample.
[0207] X-ray diffraction pattern of molecular sieve sample and Figure 1 Similarly, the molecular sieve sample can be identified as ZSM-48 molecular sieve;
[0208] SEM images of molecular sieve samples and Figure 2 Similarly, the molecular sieve sample can be obtained with an elliptical nanosheet morphology formed by the aggregation of nanoparticles, and specifically the morphology of the intersecting nanosheets. The length of the nanoparticles is 20 nm, the thickness of the nanosheets is 16 nm, the length is 370 nm, the width is 200 nm, the length-to-thickness ratio is 23.1, and the length-to-width ratio is 1.9.
[0209] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 53 using inductively coupled plasma atomic emission spectrometry (ICP).
[0210] N2 physisorption diagram of molecular sieve samples and Figure 3 Similarly, the specific surface area of molecular sieves is 311 m². 2 / gram, with an external specific surface area of 146 m² measured by the BET method. 2 / g; Total pore volume 0.42cm 3 / gram, micropore volume is 0.08 cm³ 3 / gram.
[0211] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0212] NH3-TPD diagram of hydrogen-form ZSM-48 molecular sieve and Figure 4 Similarly, the total acid content of the molecular sieve sample was found to be 596 μmol / g, the strong acid content was 186 μmol / g, and the strong acid content accounted for 31% of the total acid content.
[0213] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reaches the highest level of 68%.
[0214] Comparative Example 1
[0215] The method is the same as in Example 4, except that 1,6-hexanediamine is used as a structure directing agent, and the mass of 1,6-hexanediamine is controlled so that the molar ratio of the final mixture is:
[0216] SiO2 / Al2O3 = 59;
[0217] NaOH / SiO2 = 0.36;
[0218] SDA / SiO2 = 0.07;
[0219] H2O / SiO2 = 41;
[0220] The final mixture was placed in a stainless steel reactor and heated for crystallization at 150°C for 4 days under static crystallization conditions. After crystallization, the mixture was filtered, washed with water, dried overnight in an oven at 100°C, and then calcined in air at 550°C for 6 hours to obtain the molecular sieve sample. The X-ray diffraction pattern of the molecular sieve sample is shown in the figure. Figure 1 Similarly, the molecular sieve sample was identified as ZSM-48 molecular sieve; the SEM image of the molecular sieve sample is shown below. Figure 9 As shown, it has a rod-like morphology, not a nanosheet-like morphology.
[0221] The molecular sieve sample was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65℃ for 3 hours, centrifuged and washed, and the above steps were repeated twice. After drying at 100℃ overnight, the sample was calcined in air at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve.
[0222] Hydroisomerization was performed using hydrogen-form ZSM-48 molecular sieves. The catalyst loading was 0.4 g with a particle size of 20-40 mesh. The molar ratio of hydrogen to n-heptane was 2:6. The reaction temperature was 200-400 °C, and the weight hourly space velocity was 1 h⁻¹. -1 Within the temperature range of 280-320℃, the yield of the isomer product reached the highest level of 41%.
[0223] The results of the above examples and comparative examples show that the isomer yields of the nanosheet ZSM-48 molecular sieves with the specific morphology of the present invention in Examples 1-8 are significantly better than those of the rod-shaped ZSM-48 molecular sieve in Comparative Example 1 during the isomerization reaction.
[0224] 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 nanosheet-like ZSM-48 molecular sieve, characterized in that, The molecular sieve has a nanosheet-like morphology formed by the aggregation of nanoparticles, wherein the length of the nanoparticles is no higher than 50 nm, and the length of the nanosheets is no higher than 1000 nm; the total specific surface area of the molecular sieve is no less than 300 m². 2 / gram, external specific surface area not less than 100 m² 2 / gram.
2. The molecular sieve according to claim 1, wherein, The nanoparticles have a length of 10-50 nm; and / or The molecular sieve has a nanosheet cross-shaped morphology; and / or The nanosheets are elliptical in shape.
3. The molecular sieve according to claim 2, wherein, The length of the nanoparticles is 15-45 nm.
4. The molecular sieve according to claim 1, wherein, The nanosheets have a length of 300-900 nm; and / or The thickness of the nanosheet is 10-100 nm; and / or The width of the nanosheet is 200-800 nm.
5. The molecular sieve according to claim 4, wherein, The nanosheets have a length of 300-800 nm; and / or The thickness of the nanosheets is 10-80 nm; and / or The width of the nanosheet is 200-700 nm.
6. The molecular sieve according to claim 4, wherein, The aspect ratio of the nanosheet is 1-2; and / or The aspect ratio of the nanosheets is 5-30.
7. The molecular sieve according to claim 6, wherein, The aspect ratio of the nanosheets is 1.1-1.9; and / or The aspect ratio of the nanosheet is 5-25.
8. The molecular sieve according to claim 1, wherein, The SiO2 / Al2O3 molar ratio of the molecular sieve is 40-250; and / or The total specific surface area of the molecular sieve is 300-500 m². 2 / gram; and / or The molecular sieve has an external specific surface area of 100-250 m². 2 / gram.
9. The molecular sieve according to claim 8, wherein, The SiO2 / Al2O3 molar ratio of the molecular sieve is 50-240.
10. The molecular sieve according to claim 1, wherein, The total pore volume of the molecular sieve is not less than 0.25 cm³. 3 / gram; and / or The molecular sieve has a micropore volume of not less than 0.05 cm³. 3 / gram.
11. The molecular sieve according to claim 10, wherein, The total pore volume of the molecular sieve is 0.25-0.6 cm. 3 / gram; and / or The molecular sieve has a micropore volume of 0.05-0.2 cm³. 3 / gram.
12. The method for preparing the ZSM-48 molecular sieve according to any one of claims 1-11, characterized in that, The preparation method includes: The mixture formed by raw materials containing silicon source, aluminum source, structure guiding agent and alkali source is subjected to heating crystallization treatment; The structure-directing agent is composed of structural unit a as shown in formula (1). Equation (1), In equation (1), X is a halogen or OH, and * represents a linking site.
13. The preparation method according to claim 12, wherein, The average degree of polymerization of the structure-directing agent is 2-20; and / or The silicon source is calculated as SiO2, the aluminum source as Al2O3, the structure directing agent as structural unit a, and the alkali source as cation. The molar ratio of the silicon source, aluminum source, structure directing agent, alkali source, and water in the mixture is 1:a:b:c:d, where a is 0.004-0.03, b is 0.03-0.1, c is 0.10-0.5, and d is 8-100.
14. The preparation method according to claim 13, wherein, The structure-directing agent has an average degree of polymerization of 3-12; and / or a is 0.004-0.025; and / or b is 0.04-0.09; and / or c is 0.15-0.45; and / or d is 10-90.
15. The preparation method according to claim 12, wherein, Crystallization conditions include: crystallization at 130-190℃ for 2-14 days; and / or After crystallization, solid-liquid separation and heat treatment are carried out. The conditions for heat treatment include: drying followed by calcination.
16. The preparation method according to claim 15, wherein, Crystallization conditions include: crystallization at 140-180℃ for 3-12 days; and / or The calcination conditions include: a calcination temperature of 300-800℃; and / or a calcination time of 1-10 hours; and / or calcination under an oxygen-containing atmosphere.
17. The use of the ZSM-48 molecular sieve according to any one of claims 1-11 in adsorption treatment and / or organic compound conversion reactions.
18. A method for preparing hydrogen-form ZSM-48 molecular sieve, characterized in that, The preparation method includes: The hydrogen-form ZSM-48 molecular sieve is obtained by performing ammonium exchange and solid-liquid separation on the ZSM-48 molecular sieve according to any one of claims 1-11, followed by heat treatment.
19. The hydrogen-form ZSM-48 molecular sieve prepared by the preparation method according to claim 18.
20. The hydrogen-form ZSM-48 molecular sieve according to claim 19, wherein, The total acid content of the hydrogen-form ZSM-48 molecular sieve is not less than 150 μmol / g; and / or The strong acid content of the hydrogen-form ZSM-48 molecular sieve is not less than 70 μmol / g; and / or The proportion of strong acid in the hydrogen-type ZSM-48 molecular sieve is not less than 25% of the total acid content.
21. The hydrogen-form ZSM-48 molecular sieve according to claim 20, wherein, The total acidity of the hydrogen-form ZSM-48 molecular sieve is 150-1000 μmol / g; and / or The strong acid content of the hydrogen-form ZSM-48 molecular sieve is 70-500 μmol / g; and / or The proportion of strong acid in the hydrogen-type ZSM-48 molecular sieve is 25-50% of the total acid content.
22. The application of the hydrogen-form ZSM-48 molecular sieve according to claim 19 in adsorption treatment and / or organic compound conversion reactions.