Hydrogen-type molecular sieve, synthesis method and application thereof

Abstract

This invention relates to a hydrogen-form ZSM-48 molecular sieve, its synthesis method, and its applications. The hydrogen-form ZSM-48 molecular sieve has an average mesopore size of 6 nm to 30 nm, a B / L acid ratio of 0.7 to 3.4, and a specific surface area of ​​100 m². 2 / g~500m 2 / g. The synthesis method of the hydrogen-form ZSM-48 molecular sieve includes the following steps: (1) Under contact conditions, silicon source, aluminum source, template agent and water are mixed evenly to obtain a gel; (2) The gel obtained in step (1) is subjected to hydrothermal crystallization treatment, and then washed, dried and calcined to obtain hydrogen-form ZSM-48 molecular sieve. The template agent in step (1) includes hexamethylammonium hydroxide and urea; preferably, the template agent also includes urease. The synthesis method controls the molecular sieve pore size and B / L acid ratio by introducing urease and using a two-stage hydrothermal treatment method, thereby realizing the control of molecular sieve properties according to the target reaction characteristics, which is beneficial to improving the yield of low-branched isoalkanes and improving the quality of lubricating oil base oil.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology and relates to a molecular sieve, its synthesis method and application, specifically to a hydrogen-form ZSM-48 molecular sieve, its synthesis method and application. Background Technology

[0002] Isomerization dewaxing is a key technology for producing high-quality lubricating oil base oils. It primarily involves isomerizing high-pour-point n-alkanes in feedstock oils to generate branched isoalkanes, thereby lowering their pour point. However, isoalkanes have poor viscosity-temperature properties, and these properties worsen with increasing isomerization, failing to meet performance requirements. Lubricating oil base oils, in addition to requiring a high pour point, also need good viscosity-temperature properties. Therefore, to ensure good performance in lubricating oil base oils, low-branched isoalkanes are ideal components.

[0003] To maximize the formation of few-branched isoalkanes during isomerization, the isomerization catalyst needs suitable acidity and pore structure. Suitable acidity enhances catalytic activity, while a suitable pore structure improves selectivity for isoalkanes. One-dimensional ten-membered ring pore structures are considered suitable molecular sieve pore structures for isomerization dewaxing reactions. This is mainly due to the characteristics of the one-dimensional ten-membered ring pore structure, which allows single-branched alkanes to diffuse freely, while the diffusion of multi-branched alkanes is restricted due to shape-selective effects. Furthermore, the ten-membered ring structure can reduce the formation of multi-branched alkanes, inhibit cracking reactions, and improve the selectivity for isoalkanes. Simultaneously, the ten-membered ring pore structure can reduce coking reactions by controlling the formation of fused-ring aromatics, thereby increasing the catalyst's lifespan.

[0004] ZSM-48 molecular sieve is a molecular sieve with one-dimensional ten-membered ring straight channels. It has an orthogonal or pseudo-orthogonal symmetry structure and a channel diameter of 0.53 nm × 0.56 nm, which meets the requirements of molecular sieve channel structure in the lock-and-key reaction mechanism. It is considered to be a catalytic material suitable for isomerization reaction.

[0005] US4397827A discloses a method for synthesizing ZSM-48 molecular sieves and their catalytic conversion applications. Needle-shaped ZSM-48 molecular sieves are synthesized using tetramethylammonium chloride and n-propylamine as template agents. However, trace amounts of octahedral metastable ZSM-48 precursors are present in the crystallized product after the reaction. CN112142066A discloses a method for synthesizing ZSM-48 molecular sieves using a dual-template agent approach, employing hexadecyltrimethylammonium chloride (CTAC) and 1,6-hexanediamine as dual template agents in the preparation of ZSM-48 molecular sieves. CN111137905A discloses ZSM-48 molecular sieves and their preparation method, using a two-stage crystallization method to synthesize ZSM-48 molecular sieves with silicon-rich centers and aluminum-rich shells. The silicon-to-aluminum ratio of the silicon-rich centers is higher than that of the aluminum-rich shells, thus allowing more effective acidic centers to be concentrated on the outer surface. CN109704362A discloses a ZSM-48 molecular sieve, its preparation method and application, which prepares a ZSM-48 molecular sieve containing a mesoporous structure by appropriately chemically treating the crystallized mother liquor.

[0006] The ZSM-48 molecular sieve disclosed above has a small pore size, which is not conducive to molecular diffusion. When applied to the field of catalytic isomerization, it is prone to over-isomerization. Furthermore, the acidity of the molecular sieve cannot fully meet the requirements of catalytic isomerization reactions, which is not conducive to the formation of low-branched isoalkanes. In addition, the synthesis method of ZSM-48 molecular sieve is mainly a hydrothermal method, which involves adjusting the proportions of alkali source, template agent, silicon source, aluminum source, and water source under suitable composition and crystallization conditions. The alkali source is usually an inorganic base such as sodium hydroxide, and the synthesized molecular sieve contains alkali metals. In order to make the molecular sieve catalyst have catalytic activity, the sodium-type molecular sieve needs to be ion-exchanged to form a hydrogen-type molecular sieve. This process not only consumes a lot of water and energy, but also generates a lot of wastewater, which is not conducive to the green synthesis of molecular sieves. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the main objective of this invention is to provide a hydrogen-form ZSM-48 molecular sieve, its synthesis method, and its applications. The hydrogen-form ZSM-48 molecular sieve has a relatively large mesopore size and a suitable B / L acid ratio. The synthesis method involves introducing urease during the molecular sieve synthesis process and employing a two-stage hydrothermal treatment method to regulate the sieve pore size and B / L acid ratio, thereby achieving control over the molecular sieve properties according to the target reaction characteristics. The catalyst prepared from the molecular sieve is used in the isomerization dewaxing process of hydrocarbon-containing materials, which is beneficial for improving the selectivity of low-branched isoalkanes and enhancing the viscosity-temperature properties of lubricating oil base oils.

[0008] The first aspect of this invention provides a hydrogen-form ZSM-48 molecular sieve, wherein the molecular sieve has one-dimensional ten-membered ring straight channels, with an average mesopore diameter of 6 nm to 30 nm and a B / L acid ratio of 0.7 to 3.4, preferably with an average mesopore diameter of 15 nm to 29 nm and a B / L acid ratio of 0.8 to 3.0. More preferably, the average mesopore diameter is 20 nm to 28 nm and the B / L acid ratio is 0.9 to 2.6.

[0009] Furthermore, the specific surface area of ​​the aforementioned hydrogen-form ZSM-48 molecular sieve is 100 m². 2 / g~500m 2 / g, preferably with a specific surface area of ​​180m² 2 / g~350m 2 / g.

[0010] A second aspect of this invention provides a method for synthesizing hydrogen-form ZSM-48 molecular sieves, comprising the following steps:

[0011] (1) Under contact conditions, the silicon source, aluminum source, template agent and water are mixed evenly to obtain a gel;

[0012] (2) The gel obtained in step (1) is subjected to hydrothermal crystallization treatment, and then washed, dried and calcined to obtain hydrogen-type ZSM-48 molecular sieve.

[0013] Furthermore, in the above-mentioned method for synthesizing hydrogen-type ZSM-48 molecular sieve, the template agent in step (1) includes hexamethylammonium hydroxide and urea; preferably, the template agent also includes urease.

[0014] Furthermore, in the above-mentioned method for synthesizing hydrogen-type ZSM-48 molecular sieve, the molar ratio of SiO2 to Al2O3 in the gel in step (1) is 20~600, preferably 50~200.

[0015] Furthermore, in the above-mentioned method for synthesizing hydrogen-type ZSM-48 molecular sieve, in step (1), the molar ratio of H2O to SiO2 is 10~60, the molar ratio of hexamethylammonium hydroxide to SiO2 is 0.02~0.3, and the molar ratio of urea to SiO2 is 0.005~0.5; based on the amount of gel, the amount of urease added is 0.05g / L~100g / L, preferably 0.5g / L~10g / L.

[0016] Furthermore, in the above-mentioned method for synthesizing hydrogen-type ZSM-48 molecular sieve, the silicon source in step (1) is one or more of silica sol, silica fume, and tetraethyl orthosilicate; preferably silica sol.

[0017] Furthermore, in the above-mentioned synthesis method of hydrogen-type ZSM-48 molecular sieve, the aluminum source in step (1) is one or more of aluminum hydroxide, boehmite, aluminum isopropoxide, aluminum sulfate, and aluminum chloride; preferably boehmite.

[0018] Furthermore, in the above-mentioned synthesis method of hydrogen-type ZSM-48 molecular sieve, the hydrothermal crystallization treatment temperature in step (2) is 30℃~200℃, preferably 40℃~185℃; the treatment time is 0.3h~200h, preferably 2h~100h.

[0019] Furthermore, in the above-mentioned synthesis method of hydrogen-type ZSM-48 molecular sieve, the hydrothermal crystallization treatment in step (2) includes two stages of hydrothermal crystallization treatment. The first stage of hydrothermal crystallization treatment can be static crystallization or dynamic crystallization, preferably dynamic crystallization. Generally, the temperature of the first stage of hydrothermal crystallization treatment is 30℃~70℃; the treatment time is 0.3h~12h, preferably 2h~6h. The second stage of hydrothermal crystallization treatment can be static crystallization or dynamic crystallization, preferably dynamic crystallization. The temperature of the second stage of hydrothermal crystallization treatment is 150℃~200℃, and the crystallization time is 10h~200h, preferably 20h~100h. More preferably, the temperature of the second stage of hydrothermal crystallization treatment is 80℃~170℃ higher than the temperature of the first stage of hydrothermal crystallization treatment, preferably 95℃~155℃ higher.

[0020] Furthermore, in the above-mentioned method for synthesizing hydrogen-type ZSM-48 molecular sieve, the gel obtained in step (1) is preferably further mixed with ZSM-48 molecular sieve before undergoing hydrothermal crystallization treatment, wherein the amount of ZSM-48 molecular sieve added is 0.01%~6% by mass of silica. The ZSM-48 molecular sieve can be a product obtained by the synthesis method of the present invention, or it can be a commercially available ZSM-48 molecular sieve product after dealkali metal ion removal.

[0021] Furthermore, in the above-mentioned method for synthesizing hydrogen-type ZSM-48 molecular sieve, the washing in step (2) can be any of the existing washing methods in the art, specifically, it can be washed with water several times, generally 1-6 times, until the filtrate is neutral.

[0022] Furthermore, in the above-mentioned synthesis method of hydrogen-type ZSM-48 molecular sieve, the drying conditions in step (2) are as follows: the drying temperature is 60℃~150℃, preferably 80℃~120℃; the drying time is 2h~24h, preferably 4h~12h.

[0023] Furthermore, in the above-mentioned synthesis method of hydrogen-type ZSM-48 molecular sieve, the calcination conditions in step (2) are as follows: the calcination temperature is 400℃~650℃, preferably 450℃~600℃; the calcination time is 2h~20h, preferably 4h~8h.

[0024] A third aspect of this invention provides a hydrogen-form ZSM-48 molecular sieve obtained using the above-described synthesis method. The hydrogen-form ZSM-48 molecular sieve has an average mesopore size of 6 nm to 30 nm and a B / L acid ratio of 0.7 to 3.4, preferably an average mesopore size of 15 nm to 29 nm and a B / L acid ratio of 0.8 to 3.0. More preferably, the average mesopore size is 20 nm to 28 nm and the B / L acid ratio is 0.9 to 2.6.

[0025] A fourth aspect of the present invention provides an isomer dewaxing catalyst, the catalyst comprising a support and an active metal component, wherein the support contains the above-mentioned hydrogen-form ZSM-48 molecular sieve or a hydrogen-form ZSM-48 molecular sieve obtained by the above-mentioned synthesis method.

[0026] Furthermore, in the above-mentioned isomerization dewaxing catalyst, the active metal component is at least one of the Group VIII noble metals Pt and Pd, preferably Pt.

[0027] Furthermore, in the above-mentioned isomer dewaxing catalyst, based on the final catalyst weight, the molecular sieve content is 10wt%~90wt%, preferably 20wt%~70wt%; the active metal content, calculated as metal, is 0.05wt%~5wt%, preferably 0.1wt%~1.0wt%; and the inorganic refractory oxide content is 5wt%~85wt%, preferably 30wt%~70wt%.

[0028] Furthermore, in the above-mentioned isomeric dewaxing catalyst, the inorganic refractory oxide is selected from one or more of alumina, titanium oxide, silicon oxide, boron oxide, magnesium oxide, zirconium oxide and clay, preferably alumina and / or silicon oxide, more preferably alumina; its precursor can be selected from one or more of boehmite, pseudoboehmite, boehmite monohydrate, gibbsite trihydrate and diaspore, preferably pseudoboehmite.

[0029] Furthermore, the properties of the above-mentioned isomerization dewaxing catalyst are as follows: BET specific surface area is 150 m². 2 / g~450m 2 / g, preferably with a BET specific surface area of ​​180m 2 / g~350m 2 / g; the average mesopore size is 7nm~27nm, and the B / L acid ratio is 0.4~2.5. Preferably, the average mesopore size is 10nm~25nm, and the B / L acid ratio is 0.6~2.2; more preferably, the average mesopore size is 12nm~20nm, and the B / L acid ratio is 0.7~1.9.

[0030] The fifth aspect of this invention provides a method for preparing an isomeric dewaxing catalyst, comprising the following steps:

[0031] S1. Synthesis of ZSM-48 molecular sieve;

[0032] S2. Prepare a support from the ZSM-48 molecular sieve obtained in S1;

[0033] S3. Introduce active metal components onto the carrier obtained in step S2.

[0034] Furthermore, in the above-mentioned method for preparing the isomerization dewaxing catalyst, the synthesis of ZSM-48 molecular sieve in step S1 adopts the synthesis method provided above, as follows:

[0035] (1) Under contact conditions, the silicon source, aluminum source, template agent and water are mixed evenly to obtain a gel;

[0036] (2) The gel obtained in step (1) is subjected to hydrothermal crystallization treatment, and then washed, dried and calcined to obtain hydrogen-type ZSM-48 molecular sieve.

[0037] Furthermore, in the preparation method of the above-mentioned isomer dewaxing catalyst, a carrier forming aid, such as guar gum powder or starch, can be added in step S2.

[0038] The sixth aspect of the present invention provides an application of the above-mentioned isomerization dewaxing catalyst in the isomerization dewaxing process of hydrocarbon-containing materials.

[0039] Compared with existing technologies, the advantages of the hydrogen-form ZSM-48 molecular sieve, its synthesis method, and its applications provided by this invention are as follows:

[0040] (1) The method for synthesizing hydrogen-form ZSM-48 molecular sieve provided by this invention uses hexamethylammonium hydroxide, urea, and urease as a mixed template agent to directly synthesize hydrogen-form ZSM-48 molecular sieve in situ. Hexamethylammonium hydroxide can provide both template agent and base source, while urea, after dissolving in the reaction system, forms a homogeneous solution system, further providing base source and ammonium cations, and can make hydroxide ions and ammonium cations uniformly distributed in the reaction system. Furthermore, the introduction of urease will promote the hydrolysis reaction of urea, and the activity of urease can be controlled by two-stage hydrothermal crystallization at different operating temperatures to control the degree of hydrolysis and regulate alkalinity, which is beneficial to the formation of molecular sieve. In addition, urease can also play the role of pore expander in the subsequent molecular sieve calcination process, which can increase the pore size of the molecular sieve and facilitate molecular diffusion.

[0041] (2) The urease used in this invention is a nickel-containing oligopeptidase, which, after molecular sieve crystallization and calcination, has unsaturated empty orbitals in Ni. δ+ Introduced into molecular sieves, while Ni δ+The number of empty orbitals is related to the number of Lewis acid sites, thereby modulating the B / L acid ratio of the molecular sieve to make it more suitable for the acidic components required for catalytic isomerization reactions.

[0042] (3) This invention provides a method for direct in-situ synthesis of hydrogen-form ZSM-48 molecular sieve, which can eliminate the ammonium exchange operation in the existing method for preparing hydrogen-form ZSM-48 molecular sieve. Hydrothermal crystallization products can be directly obtained after drying and calcination, avoiding the problem of generating a large amount of wastewater by using the ammonium exchange process. It reduces the preparation cost and also greatly reduces environmental pollution, making it a green synthesis method. Attached Figure Description

[0043] Figure 1 This is the XRD pattern of the molecular sieve synthesized in Example 5 of the present invention. Implementation

[0044] The following examples further illustrate the function and effect of the method of the present invention, but the following examples do not constitute a limitation on the method of the present invention. The endpoints and any values ​​of the disclosed ranges are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range 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. Unless otherwise specified, all contents in the following examples are weight percentages. The specific surface area and pore size of the samples of the present invention were determined by N2 adsorption-desorption using an ASAP 2405 physical adsorption instrument; the crystal phase structure of the samples of the present invention was characterized by a D / max-2500 fully automatic rotating target X-ray diffractometer; and the B / L acid ratio of the samples of the present invention was determined by pyridine adsorption-desorption using a Nicolet iS20 Fourier transform infrared spectrometer.

[0045] Example 1

[0046] Urea, hexamethylammonium hydroxide (HMH), silica sol, pseudoboehmite, and water were mixed in a molar ratio of 0.1CO(NH2)2:0.02HMH:SiO2:0.005Al2O3:40H2O, with urease added at 2 g / L, to form a gel. This gel was then placed in a crystallization vessel and subjected to hydrothermal crystallization at 200℃ for 20 h. After crystallization, the product was washed, dried at 110℃ for 6 h, and then calcined at 500℃ for 5 h to obtain hydrogen-form ZSM-48 molecular sieve Z1 with a specific surface area of ​​213 m². 2 / g, with an average mesopore diameter of 20nm and a B / L acid ratio of 2.1.

[0047] 210g of the hydrogen-form ZSM-48 molecular sieve (dry basis, the same below) prepared above was thoroughly mixed with 70g of pseudoboehmite (dry basis). 2.5mL of concentrated nitric acid (65% by mass) and an appropriate amount of water were added, and the mixture was thoroughly kneaded and then extruded into strips. The shaped support was dried at 100℃ for 4h and calcined at 550℃ for 4h to obtain the support. Then, noble metal Pt was impregnated using a saturated impregnation method, with a Pt loading of 0.30wt% of the support. After drying at 100℃ for 4h and calcining at 500℃ for 3h, the catalyst C1 of this invention was obtained, with a specific surface area of ​​218m². 2 / g, the average pore size of the mesopores is 17nm, the B / L acid ratio is 2.0, and the evaluation results are shown in Table 2.

[0048] Example 2

[0049] Urea, hexamethylammonium hydroxide (HMH), silica, aluminum hydroxide, and water were mixed uniformly in a molar ratio of 0.08CO(NH2)2:0.1HMH:SiO2:0.0125Al2O3:10H2O to form a gel. Then, 1% (w / w) of ZSM-48 molecular sieve was added, and the mixture was placed in a crystallization vessel. Hydrothermal crystallization was then carried out at 180℃ for 28 hours. After crystallization, the product was washed, dried at 110℃ for 6 hours, and then calcined at 500℃ for 5 hours to obtain hydrogen-form ZSM-48 molecular sieve Z2 with a specific surface area of ​​237 m². 2 / g, with an average mesopore diameter of 8nm and a B / L acid ratio of 3.4.

[0050] The catalyst was prepared using the same method as in Example 1, except that the weight content of the hydrogen-form ZSM-48 molecular sieve in the catalyst support was 35%, the boehmite was replaced with alumina, and the metal loading in the catalyst was 0.23%, resulting in catalyst C2 of the present invention with a specific surface area of ​​255 m². 2 / g, the average pore size of the mesopores is 9nm, the B / L acid ratio is 1.6, and the evaluation results are shown in Table 2.

[0051] Example 3

[0052] Urea, hexamethylammonium hydroxide (HMH), tetraethyl orthosilicate, aluminum sulfate, and water were mixed in a molar ratio of 0.2CO(NH2)2:0.2HMH:SiO2:0.0125Al2O3:60H2O, with urease added at 10 g / L to form a gel. The gel was then placed in a crystallization vessel and dynamically crystallized at 70°C for 2 hours. Following this, the temperature was increased to 170°C for hydrothermal crystallization for 48 hours. After crystallization, the product was washed, dried at 110°C for 6 hours, and then calcined at 500°C for 5 hours to obtain hydrogen-form ZSM-48 molecular sieve Z3, with a specific surface area of ​​186 m². 2 / g, with an average mesopore diameter of 28nm and a B / L acid ratio of 0.9.

[0053] The catalyst was prepared using the same method as in Example 1, except that the weight content of the hydrogen-form ZSM-48 molecular sieve in the catalyst support was 50%, and the metal loading in the catalyst was 0.41%, resulting in catalyst C3 of the present invention with a specific surface area of ​​204 m². 2 / g, the average pore size of the mesopores is 20nm, the B / L acid ratio is 0.7, and the evaluation results are shown in Table 2.

[0054] Example 4

[0055] Urea, hexamethylammonium hydroxide (HMH), silica sol, aluminum isopropoxide, and water were mixed in a molar ratio of 0.005CO(NH2)2:0.3HMH:SiO2:0.01Al2O3:25H2O, with urease added at 0.5 g / L to form a gel. The gel was placed in a crystallization vessel and dynamically crystallized at 30℃ for 6 hours, followed by hydrothermal crystallization at 180℃ for 24 hours. After crystallization, the product was washed, dried at 110℃ for 6 hours, and then calcined at 500℃ for 5 hours to obtain hydrogen-form ZSM-48 molecular sieve Z4 with a specific surface area of ​​224 m². 2 / g, with an average mesopore diameter of 15nm and a B / L acid ratio of 2.6.

[0056] The catalyst was prepared using the same method as in Example 1, except that the boehmite used in the catalyst support preparation process was replaced with alumina, and the metal loading in the catalyst was 0.38%, resulting in catalyst C4 of the present invention with a specific surface area of ​​230 m². 2 / g, the average pore size of the mesopores is 12nm, the B / L acid ratio is 1.9, and the evaluation results are shown in Table 2.

[0057] Example 5

[0058] Urea, hexamethylammonium hydroxide (HMH), silica sol, pseudoboehmite, and water were mixed in a molar ratio of 0.5CO(NH2)2:0.15HMH:SiO2:0.02Al2O3:50H2O, with urease added at 4 g / L to form a gel. The gel was placed in a crystallization vessel and dynamically crystallized at 60℃ for 6 hours, followed by hydrothermal crystallization at 185℃ for 24 hours. After crystallization, the product was washed, dried at 110℃ for 6 hours, and then calcined at 550℃ for 4 hours to obtain hydrogen-form ZSM-48 molecular sieve Z5 with a specific surface area of ​​205 m². 2 / g, with an average mesopore diameter of 25nm and a B / L acid ratio of 1.2.

[0059] The catalyst was prepared using the same method as in Example 1, except that the weight content of the hydrogen-form ZSM-48 molecular sieve in the catalyst support was 40%, the boehmite was replaced with alumina, and the metal loading in the catalyst was 0.40%, resulting in catalyst C5 of the present invention with a specific surface area of ​​223 m². 2 / g, the average pore size of the mesopores is 16nm, the B / L acid ratio is 1, and the evaluation results are shown in Table 2.

[0060] The performance of the catalyst prepared above was evaluated using a medium-sized fixed-bed reactor with a catalyst loading of 200 mL. The catalyst needed to be reduced before feeding under the following conditions: hydrogen atmosphere, reduction temperature of 400℃, reduction pressure of 8.0 MPa, and reduction time of 8 h.

[0061] The main properties of the feedstock oil used for catalyst performance evaluation are shown in Table 1.

[0062] Table 1 Main Properties of Raw Materials

[0063]

[0064] Table 2 Catalyst performance evaluation results

[0065]

Claims

1. A method for synthesizing hydrogen-form ZSM-48 molecular sieve, characterized in that: The synthesis method of the hydrogen-form ZSM-48 molecular sieve includes the following steps: (1) Under contact conditions, the silicon source, aluminum source, template agent and water are mixed evenly to obtain a gel; (2) The gel obtained in step (1) was subjected to hydrothermal crystallization treatment, and then washed, dried and calcined to obtain hydrogen-type ZSM-48 molecular sieve; The template agent in step (1) includes hexamethylammonium hydroxide and urea, and also includes urease; The hydrothermal crystallization process in step (2) includes two stages of hydrothermal crystallization, which can be static or dynamic. The temperature of the first stage of hydrothermal crystallization is 30℃~70℃ and the processing time is 0.3h~12h. The temperature of the second stage of hydrothermal crystallization is 150℃~200℃ and the crystallization time is 10h~200h. The average pore size of the hydrogen-type ZSM-48 molecular sieve is 6 nm to 30 nm, and the B / L acid ratio is 0.7 to 3.

4.

2. The synthesis method according to claim 1, characterized in that: In step (1), the molar ratio of SiO2 to Al2O3 in the gel is 20~600; the molar ratio of H2O to SiO2 is 10~60; the molar ratio of hexamethylammonium hydroxide to SiO2 is 0.02~0.3; the molar ratio of urea to SiO2 is 0.005~0.5; and the amount of urease added is 0.05g / L~100g / L based on the amount of gel.

3. The synthesis method according to claim 2, characterized in that: In step (1), the molar ratio of SiO2 to Al2O3 in the gel is 50 to 200; based on the amount of gel, the amount of urease added is 0.5 g / L to 10 g / L.

4. The synthesis method according to claim 1, characterized in that: In step (1), the silicon source is one or more of silica sol, silica fume, and tetraethyl orthosilicate.

5. The synthesis method according to claim 4, characterized in that: In step (1), the silicon source is silica sol.

6. The synthesis method according to claim 1, characterized in that: In step (1), the aluminum source is one or more of aluminum hydroxide, boehmite, aluminum isopropoxide, aluminum sulfate, and aluminum chloride.

7. The synthesis method according to claim 6, characterized in that: In step (1), the aluminum source is boehmite.

8. The synthesis method according to claim 1, characterized in that: The hydrothermal crystallization process in step (2) includes two stages of hydrothermal crystallization, which adopts dynamic crystallization. The first stage of hydrothermal crystallization takes 2 hours to 6 hours, and the second stage of hydrothermal crystallization takes 20 hours to 100 hours.

9. The synthesis method according to claim 1, characterized in that: In step (2), the temperature of the second stage of hydrothermal crystallization treatment is 80℃~170℃ higher than that of the first stage of hydrothermal crystallization treatment.

10. The synthesis method according to claim 9, characterized in that: In step (2), the temperature of the second stage of hydrothermal crystallization treatment is 95℃~155℃ higher than that of the first stage of hydrothermal crystallization treatment.

11. The synthesis method according to claim 1, characterized in that: The gel obtained in step (1) is further mixed with ZSM-48 molecular sieve and then subjected to hydrothermal crystallization treatment. The mass ratio of the amount of ZSM-48 molecular sieve added to the amount of silica added is 0.01%~6%.

12. The synthesis method according to claim 1, characterized in that: In step (2), the washing process involves washing with water 1-6 times until the filtrate is neutral.

13. The synthesis method according to claim 1, characterized in that: The drying conditions in step (2) are as follows: drying temperature is 60℃~150℃; drying time is 2h~24h.

14. The synthesis method according to claim 13, characterized in that: The drying conditions in step (2) are as follows: drying temperature is 80℃~120℃; drying time is 4h~12h.

15. The synthesis method according to claim 1, characterized in that: The roasting conditions in step (2) are as follows: roasting temperature is 400℃~650℃; roasting time is 2h~20h.

16. The synthesis method according to claim 15, characterized in that: The roasting conditions in step (2) are as follows: roasting temperature is 450℃~600℃; roasting time is 4h~8h.

17. A hydrogen-form ZSM-48 molecular sieve prepared by any one of claims 1-16, characterized in that: The average pore size of the hydrogen-type ZSM-48 molecular sieve is 15nm~29nm, and the B / L acid ratio is 0.8~3.

0.

18. The hydrogen-form ZSM-48 molecular sieve according to claim 17, characterized in that: The average pore size of the hydrogen-type ZSM-48 molecular sieve is 20 nm to 28 nm, and the B / L acid ratio is 0.9 to 2.

6.

19. An isomerization dewaxing catalyst, said catalyst comprising a support and an active metal component, characterized in that: The carrier comprises hydrogen-form ZSM-48 molecular sieve prepared by any one of claims 1-16.

20. The isomerization dewaxing catalyst according to claim 19, characterized in that: The active metal component is at least one of the Group VIII noble metals Pt and Pd.

21. The isomerization dewaxing catalyst according to claim 20, characterized in that: The active metal component is Pt.

22. The isomerization dewaxing catalyst according to claim 19, characterized in that: Based on the final catalyst weight, the molecular sieve content is 10wt%~90wt%; the active metal content (in metal terms) is 0.05wt%~5wt%; and the inorganic refractory oxide content is 5wt%~85wt%.

23. The isomerization dewaxing catalyst according to claim 22, characterized in that: Based on the final catalyst weight, the molecular sieve content is 20wt%~70wt%; the active metal content (in metal terms) is 0.1wt%~1.0wt%; and the inorganic refractory oxide content is 30wt%~70wt%.

24. The isomerization dewaxing catalyst according to claim 22, characterized in that: The inorganic refractory oxide is one or more of aluminum oxide, titanium oxide, silicon oxide, boron oxide, magnesium oxide, zirconium oxide, and clay.

25. The isomerization dewaxing catalyst according to claim 24, characterized in that: The inorganic refractory oxide is aluminum oxide and / or silicon oxide.

26. The isomerization dewaxing catalyst according to claim 24, characterized in that: The inorganic refractory oxide is aluminum oxide; its precursor is selected from one or more of boehmite, pseudoboehmite, boehmite, gibbsite and diaspore.

27. The isomerization dewaxing catalyst according to claim 26, characterized in that: Its predecessor was boehmite.

28. The isomerization dewaxing catalyst according to claim 19, characterized in that: The catalyst has a BET specific surface area of ​​150 m². 2 / g~450m 2 / g; the average pore size of the mesopores is 7nm~27nm, and the B / L acid ratio is 0.4~2.

5.

29. The isomerization dewaxing catalyst according to claim 19, characterized in that: The catalyst has a BET specific surface area of ​​180 m². 2 / g~350m 2 / g; the average pore size of the mesopores is 10nm~25nm, and the B / L acid ratio is 0.6~2.

2.

30. The isomerization dewaxing catalyst according to claim 19, characterized in that: The catalyst has an average mesopore size of 12 nm to 20 nm and a B / L acid ratio of 0.7 to 1.

9.

31. A method for preparing an isomeric dewaxing catalyst, characterized in that: The preparation method includes the following steps: S1. Synthesis of ZSM-48 molecular sieve; S2. Prepare a support from the ZSM-48 molecular sieve obtained in S1; S3. Introduce active metal components onto the carrier obtained in step S2; The ZSM-48 molecular sieve synthesis method used in step S1 is the synthesis method described in any one of claims 1-16.

32. The method for preparing the isomerization dewaxing catalyst according to claim 31, characterized in that: In step S2, a carrier forming aid is added, which is guar gum powder or starch.

33. The application of any one of the isomerization dewaxing catalysts of claims 19-30 in the isomerization dewaxing process of hydrocarbon-containing materials.

Images