Hydroisomerization catalyst as well as preparation method and application thereof
By subjecting ZSM molecular sieves to alkali treatment and three-stage crystallization, a hydroisomerization catalyst with a nanoporous structure was prepared, which solved the problem of underdeveloped pores in existing catalysts and achieved high conversion rate and selectivity in the isomerization reaction of long-chain alkane.
Patent Information
- Application Number
- CN202411675455.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2026-05-22
AI Technical Summary
Existing hydrogenation catalysts have insufficiently developed pores in the isomerization of long-chain n-alkane oils, which makes it difficult for feedstocks and isomers to desorb and diffuse, thus affecting the yield of isomers.
Modified ZSM molecular sieves were prepared by alkali treatment and three-stage crystallization, and active components were loaded onto them to form a hydroisomer catalyst with a nanoporous structure, which improved diffusion performance and pore distribution uniformity.
This method improves the conversion rate and isomer selectivity of the hydrogenation isomerization reaction of long-chain alkanes, and is easy to industrialize.
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Figure CN122071644A_ABST
Abstract
Description
Technical Field
[0001] This disclosure pertains to the field of hydrogenation catalysts, specifically relating to a hydrogenation isomer catalyst, its preparation method, and its applications. Background Technology
[0002] Fixed-bed hydrotreating catalysts typically require sufficient diffusion channels for reactants and products to ensure stable operation and meet required lifespan. In the isomerization of long-chain n-alkane petroleum products, the goal is to convert them into multi-linear-chain isoalkanes while maintaining the same carbon number, thereby significantly lowering the pour point of the n-alkane. However, due to the characteristic that longer hydrocarbon chains lead to faster cracking rates and greater difficulty in isomerization and pour point reduction, the isomerization performance of the catalyst is extremely demanding. Currently available isomerization catalysts often have underdeveloped pore structures, which can easily cause difficulties in the desorption and diffusion of feedstocks and isomer products, affecting the yield of isomer products. Summary of the Invention
[0003] The purpose of this invention is to provide a hydroisomerization catalyst and its preparation method. The method provided by this invention can effectively improve diffusion performance, and the modified ZSM molecular sieve prepared has a more uniform internal pore distribution and excellent isomer selectivity. It can provide sufficient active sites for the isomerization reaction of long-chain alkanes, so that the prepared hydroisomerization catalyst has excellent catalytic performance. Therefore, applying the hydroisomerization catalyst provided by this invention to the hydroisomerization reaction of long-chain alkanes can effectively improve the conversion rate and isomer selectivity of the reaction.
[0004] To achieve the above objectives, a first aspect of the present invention provides a hydroisomerization catalyst, wherein the hydroisomerization catalyst comprises a catalyst support and an active component supported on the catalyst support; the catalyst support comprises a modified ZSM molecular sieve and an inorganic oxide; the modified ZSM molecular sieve comprises a nanopore structure, the average diameter of the nanopore structure being 5-20 nm; Based on the total mass of the hydroisomerization catalyst, the loading of the active component is 0.2~0.6 wt%.
[0005] Optionally, the ZSM molecular sieve includes one or more of ZSM-48 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve and ZSM-35 molecular sieve; the active component includes a Group VIII noble metal, which includes palladium and / or platinum. The inorganic oxide is selected from one or more of alumina, silicon oxide, and amorphous aluminum silicate.
[0006] Optionally, the nanopore structure is spherical, near-spherical, or near-ellipsoidal; The BET specific surface area of the hydroisomerization catalyst is 100~300 m². 2 / g; total pore volume is 0.25~0.35ml / g; micropore volume is 0.02~0.10ml / g; mesopore volume is 0.15~0.30ml / g; In the hydroisomerization catalyst, the pore volume with a diameter of 5-20 nm accounts for 60-90% of the total pore volume.
[0007] A second aspect of the present invention provides a method for preparing a hydroisomerization catalyst, wherein the method comprises: S1. The ZSM molecular sieve is alkali-treated, and then a template agent is added to obtain a mixed slurry; S2. The mixed slurry is subjected to a three-stage crystallization treatment to obtain a modified ZSM molecular sieve; S3. The modified ZSM molecular sieve is mixed with a binder, and then subjected to molding, first drying and first calcination to obtain a catalyst support. S4. Impregnate the catalyst support in an impregnation solution containing the active component to obtain the catalyst product; The alkaline treatment includes treating the molecular sieve with an alkaline solution; The three-stage crystallization process includes a first crystallization process, a second crystallization process, and a third crystallization process; the temperature of the first crystallization process is 20~60℃; the temperature of the second crystallization process is 60~150℃; and the temperature of the third crystallization process is 150~180℃.
[0008] Optionally, the alkaline solution includes one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, and potassium carbonate; the concentration of the alkaline solution is 2 wt% or more; the ZSM molecular sieve includes one or more of ZSM-48 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, and ZSM-35 molecular sieve; the template agent includes an organic amine, preferably hexamethylammonium bromide and / or hexamethylenediamine; Optionally, the modified ZSM molecular sieve has a nanopore structure with a diameter of 5-20 nm; the modified ZSM molecular sieve has a BET specific surface area of 100-300 m². 2 / g; total pore volume is 0.20~0.30ml / g; micropore volume is 0.02~0.10ml / g, mesopore volume is 0.08~0.20ml / g; the modified ZSM molecular sieve has pores with an average diameter of 5~20nm accounting for 60~90% of the total pore volume; The mass ratio of alkali to molecular sieve in the alkaline solution is (0.01~5):10, preferably (0.5~2):10; The mass ratio of the template agent to the molecular sieve is (0.01~2):10, preferably (0.1~1):10.
[0009] Optionally, the temperature of the second crystallization treatment is 50°C or more higher than the temperature of the first crystallization treatment; The temperature of the third crystallization treatment is more than 20°C higher than the temperature of the second crystallization treatment; The processing time for the first crystallization treatment is 0.5~10h; the processing time for the second crystallization treatment is 0.5~10h; and the processing time for the third crystallization treatment is 4~48h. The modified molecular sieve has a silicon-to-aluminum molar ratio of 50 to 200.
[0010] Optionally, the binder includes one or more of boehmite, alumina, alumina sol, silica sol, and silica. The dry weight ratio of the binder to the modified molecular sieve is (0.2~0.5):(0.5~0.8). Optionally, the molding process includes: acid treatment of the mixture of the modified molecular sieve and the binder, followed by kneading and molding to obtain agglomerated mixture, and extruding the agglomerated mixture into strips; The acid treatment conditions include: the acid solution includes one or more of nitric acid, citric acid, and oxalic acid; the mass ratio of the acid in the acid solution to the dry basis of the mixture is (0.01~0.05):1; Optionally, the temperature of the first drying treatment is 80~150℃ and the time is 5~24h; the temperature of the first calcination treatment is 500~600℃ and the time is 1~6h.
[0011] Optionally, the active component comprises a compound of a Group VIII noble metal, wherein the Group VIII noble metal includes palladium and / or platinum; The mass ratio of the noble metal element in the active component to the catalyst support is (0.002~0.006):1; The immersion temperature is 0~50℃ and the time is 0.5~5h.
[0012] A third aspect of the present invention provides a hydroisomerization catalyst prepared by the method described in the second aspect of the present invention.
[0013] The fourth aspect of the present invention provides the use of the hydroisomerization catalyst described in the first or second aspect of the present invention in the isomerization of long-chain alkanes; wherein the long-chain alkanes have 10 to 100 carbon atoms.
[0014] Through the above technical solution, this invention first treats ZSM molecular sieves with alkali, then performs a three-stage crystallization process to obtain modified ZSM molecular sieves. The active component is then loaded onto the modified ZSM molecular sieves to obtain a hydroisomerization catalyst. The method provided by this invention effectively avoids the damage to the pore structure of the molecular sieve caused by conventional acid-base treatments, and achieves a high yield of molecular sieves. Simultaneously, the three-stage crystallization process directly introduces nanoscale pore structures into the molecular sieve crystals, effectively improving diffusion performance. Furthermore, the modified ZSM molecular sieve obtained has a more uniform pore distribution and excellent isomer selectivity, providing sufficient active sites for the isomerization reaction of long-chain alkanes. This results in a hydroisomerization catalyst with excellent catalytic performance. Applying the hydroisomerization catalyst provided by this invention to the hydroisomerization reaction of long-chain alkanes can effectively improve the conversion rate and isomer selectivity of the reaction. Moreover, the preparation method of the hydroisomerization catalyst provided by this disclosure uses readily available raw materials and is easily implemented for industrial production.
[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a TEM image of the hydroisomerization catalyst prepared in Example 1 of the present invention. Detailed Implementation
[0017] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0018] The first aspect of this disclosure provides a hydroisomerization catalyst, wherein the hydroisomerization catalyst includes a catalyst support and an active component supported on the catalyst support; the catalyst support includes a modified ZSM molecular sieve and an inorganic oxide; the modified ZSM molecular sieve hydroisomerization catalyst has a nanopore structure with an average diameter of 5-20 nm. Based on the total mass of the hydroisomerization catalyst, the loading of the active component is 0.2~0.6wt%, preferably 0.3~0.4wt%.
[0019] The hydroisomerization catalyst provided in this disclosure has a nanoscale porous structure with uniform pore distribution and excellent isomer selectivity, providing sufficient active sites for the isomerization reaction of long-chain alkanes. This results in the prepared hydroisomerization catalyst having excellent catalytic performance. Therefore, applying the hydroisomerization catalyst provided in this disclosure to the hydroisomerization reaction of long-chain alkanes can effectively improve the conversion rate and isomer selectivity of the reaction.
[0020] In one specific embodiment, the ZSM molecular sieve includes one or more of ZSM-48 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, and ZSM-35 molecular sieve; the active component includes a Group VIII noble metal, which includes palladium and / or platinum, preferably platinum.
[0021] According to this disclosure, the inorganic oxide in the catalyst support is derived from the calcination product of the binder. In one specific embodiment, the inorganic oxide is selected from one or more of alumina, silicon oxide, and amorphous aluminum silicate, preferably alumina.
[0022] The isomerization catalyst disclosed herein has well-developed pores, and the nanopore structure in the isomerization catalyst is spherical, near-spherical, or near-ellipsoidal, especially rich in spherical mesopores with a diameter of 5-20 nm. In one embodiment, the BET specific surface area of the hydroisomerization catalyst is 100-300 m². 2 / g, preferably 200~250m 2 / g; the total pore volume is 0.25~0.35ml / g; the micropore volume is 0.02~0.10ml / g, preferably 0.03~0.06ml / g; the mesopore volume is 0.15~0.30ml / g, preferably 0.10~0.15ml / g; the percentage of pore volume with a pore diameter of 5~20nm in the isomerization catalyst to the total pore volume is 60~90%, preferably 75~85%.
[0023] A second aspect of this disclosure provides a method for preparing a hydroisomerization catalyst, wherein the method includes: S1. The ZSM molecular sieve is alkali-treated, and then a template agent is added to obtain a mixed slurry; S2. The mixed slurry is subjected to a three-stage crystallization treatment to obtain a modified ZSM molecular sieve; S3. The modified ZSM molecular sieve is mixed with a binder, and then subjected to molding, first drying and first calcination to obtain a catalyst support. S4. Impregnate the catalyst support in an impregnation solution containing the active component to obtain the catalyst product; The alkaline treatment includes treating the molecular sieve with an alkaline solution; the concentration of the alkaline solution is 2 wt% or more, preferably 4 wt% or more, and more preferably 4-8 wt%. The three-stage crystallization process includes a first crystallization process, a second crystallization process, and a third crystallization process; the temperature of the first crystallization process is 20~60℃, preferably 30~50℃; the temperature of the second crystallization process is 60~150℃, preferably 100~140℃; and the temperature of the third crystallization process is 150~180℃, preferably 160~170℃.
[0024] The method disclosed herein effectively avoids the damage to the molecular sieve pore structure caused by conventional acid-base treatments, and achieves a high molecular sieve yield. Furthermore, the three-stage crystallization process directly introduces nanoscale pore structures within the molecular sieve crystals, effectively improving diffusion performance. The resulting modified ZSM molecular sieve exhibits a more uniform pore distribution and excellent isomer selectivity, providing ample active sites for the isomerization reaction of long-chain alkanes. This results in a hydroisomerization catalyst with excellent catalytic performance. Therefore, applying the hydroisomerization catalyst provided herein to the hydroisomerization reaction of long-chain alkanes can effectively improve the conversion rate and isomer selectivity. Moreover, the preparation method of the hydroisomerization catalyst provided herein uses readily available raw materials and is easily scalable for industrial production.
[0025] In one specific embodiment, the alkaline solution comprises one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, and potassium carbonate, preferably sodium hydroxide. The concentration of the alkaline solution is, for example, 4-6 wt%.
[0026] In one specific embodiment, the ZSM molecular sieve includes one or more of ZSM-48 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve and ZSM-35 molecular sieve, preferably ZSM-48 molecular sieve.
[0027] In one specific embodiment, the template agent comprises hexamethylammonium bromide and / or hexamethylenediamine, preferably hexamethylammonium bromide.
[0028] In one specific embodiment, the mass ratio of alkali to molecular sieve in the alkaline solution is (0.01~5):10, preferably (0.5~2):10. Preparing modified ZSM molecular sieves according to the preferred mass ratio provided in the above embodiment can further improve the isomer selectivity of the molecular sieve, providing more active sites for the isomerization reaction of long-chain alkanes, thereby further improving the conversion rate and isomer selectivity of the reaction.
[0029] In one specific embodiment, the mass ratio of the template agent to the molecular sieve is (0.01~2):10, preferably (0.1~1):10. Preparing modified ZSM molecular sieves according to the preferred mass ratio provided in the above embodiment can further improve the isomer selectivity of the molecular sieve, providing more active sites for the isomerization reaction of long-chain alkane, thereby further improving the conversion rate and isomer selectivity of the reaction.
[0030] In one specific embodiment, the temperature of the second crystallization treatment is at least 50°C higher than the temperature of the first crystallization treatment, for example, 60-80°C; and the temperature of the third crystallization treatment is at least 20°C higher than the temperature of the second crystallization treatment, for example, 30-40°C. By controlling the temperatures of the first, second, and third crystallization treatments according to the above embodiment, the pore structure of the molecular sieve can be further optimized, giving it superior isomer selectivity.
[0031] In this disclosure, the three-stage crystallization process is carried out under closed self-generated pressure.
[0032] In one specific embodiment, the processing time for the first crystallization treatment is 0.5~10 hours, preferably 1~6 hours; the processing time for the second crystallization treatment is 0.5~10 hours, preferably 1~6 hours; and the processing time for the third crystallization treatment is 4~48 hours, preferably 6~24 hours. By controlling the processing times of the first, second, and third crystallization treatments within the preferred range according to the above embodiment, the pore structure of the molecular sieve can be further optimized, giving it superior isomer selectivity. Furthermore, in the above preferred embodiment, the acid-base treatment method does not need to be repeatedly used, thus avoiding dealuminization of the molecular sieve framework.
[0033] In one specific embodiment, the silicon-to-aluminum molar ratio of the modified molecular sieve can be 50-200, preferably 80-150.
[0034] In one specific embodiment, the binder includes one or more of boehmite, alumina, aluminum sol, silica sol, and silicon oxide, preferably boehmite and / or alumina.
[0035] In one specific embodiment, the dry basis mass ratio of the binder to the modified molecular sieve is (0.2~0.5):(0.5~0.8), preferably (0.3~0.4):(0.6~0.7).
[0036] In one specific embodiment, the molding process includes acid treatment of the mixture of the modified molecular sieve and the binder, followed by kneading and molding to obtain a lumpy mixture; and then extruding the lumpy mixture into strips. The acid treatment conditions include: the acid solution includes one or more of nitric acid, citric acid, and oxalic acid; the mass ratio of the acid in the acid solution to the dry basis of the mixture is (0.01~0.05):1, preferably (0.02~0.04):1. In this disclosure, the extrusion molding process and conditions are conventional operations known in the art and will not be described in detail here.
[0037] In one specific embodiment, the shaped carrier undergoes a first drying treatment followed by a first calcination treatment, wherein the temperature of the first drying treatment is 80~150℃ and the time is 5~24h; the temperature of the first calcination treatment is 500~600℃ and the time is 1~6h.
[0038] In one specific embodiment, the impregnation solution includes an active component, which comprises a compound of a Group VIII noble metal, including palladium and / or platinum, preferably platinum. In this disclosure, the impregnation solution is one or more of chloroplatinic acid, dichlorotetramineplatinum, and ammonium platinum nitrate. In the above embodiments, loading the active metal onto the modified ZSM molecular sieve further increases the active sites on the ZSM molecular sieve, giving the prepared hydroisomerization catalyst excellent catalytic performance. Therefore, applying the hydroisomerization catalyst provided in this disclosure to the hydroisomerization reaction of long-chain alkanes can effectively improve the conversion rate and isomer selectivity of the reaction.
[0039] In one specific embodiment, the mass ratio of the noble metal element in the active component to the catalyst support is (0.002~0.006):1. Preferably, it is (0.003~0.004):1. The preferred mass ratio in the above embodiment can further increase the active sites on the catalyst support, thereby further improving the conversion rate and isomer selectivity of the hydroisomerization catalyst provided in this disclosure in the hydroisomerization reaction of long-chain alkanes.
[0040] In one specific embodiment, the impregnation temperature is 0~50℃, preferably 20~40℃, and the time is 0.5~5h, preferably 1~2h. Further, after the impregnation treatment, a second drying treatment and a second calcination treatment can be performed to obtain the catalyst product. The drying and calcination conditions can be conventional in the art, for example, the second drying treatment temperature is 100~120℃, and the time is 12~24h; the second calcination treatment temperature is 400~500℃, and the time is 2~4h.
[0041] In one specific embodiment, the modified ZSM molecular sieve has a nanopore structure with a diameter of 5-20 nm; the BET specific surface area of the ZSM molecular sieve is 100-300 m². 2 / g; micropore volume is 0.02~0.10ml / g, mesopore volume is 0.08~0.20ml / g.
[0042] The third aspect of this disclosure provides a hydroisomerization catalyst prepared using the method described in the second aspect of this disclosure.
[0043] This disclosure provides, in its fourth aspect, the use of the hydroisomerization catalyst described in the first or second aspect in the isomerization of long-chain alkanes; wherein the long-chain alkane has 10 to 100 carbon atoms. Specifically, the long-chain alkane can be one or more of n-hexadecane, eicosane, Fischer-Tropsch heavy oil, Fischer-Tropsch wax, and biomass oil. The process methods and conditions for the isomerization reaction can vary within a wide range, for example, using a fixed-bed reactor, a reaction temperature of 200 to 400°C, a pressure of atmospheric pressure to 20 MPa, a space velocity of 0.2 to 3.0, and a hydrogen-to-hydrocarbon molar ratio of 5 to 40.
[0044] The present invention will be further illustrated by the following examples, but the invention is not limited thereto. All reagents used in this disclosure can be purchased through conventional channels or prepared by known methods.
[0045] Example 1 S1. 10g of ZSM-48 molecular sieve powder (commercially available, silicon-aluminum molar ratio of 120) is treated with alkali, then a template agent is added and stirred evenly to obtain a mixed slurry; the alkali solution is a NaOH solution with a concentration of 5wt%; the mass ratio of alkali to ZSM-48 molecular sieve powder in the alkali solution is 0.5:10; the mass ratio of template agent to ZSM-48 molecular sieve powder is 0.2:10; the template agent is hexamethylammonium bromide.
[0046] S2. The mixed slurry from step S1 is transferred to a crystallization reactor and subjected to a three-stage crystallization process under stirring conditions to obtain modified ZSM molecular sieve. The three-stage crystallization process includes a first crystallization process, a second crystallization process, and a third crystallization process. The crystallization pressure of the three-stage crystallization process is a closed self-generated pressure. The temperature of the first crystallization process is 40℃ and the time is 6h. The temperature of the second crystallization process is 120℃ and the time is 6h. The temperature of the third crystallization process is 170℃ and the time is 12h.
[0047] S3, (1) Mix the modified ZSM molecular sieve from step S2 with the binder to obtain a mixture, then add nitric acid solution, knead and shape to obtain agglomerated modified ZSM molecular sieve; (2) Extrude the agglomerated modified ZSM molecular sieve into strips, then perform the first drying treatment and the first calcination treatment in sequence to obtain the catalyst support; The binder is pseudoboehmite; the dry weight ratio of modified ZSM molecular sieve to binder is 7:3; the concentration of nitric acid is 5wt%; the mass ratio of acid in nitric acid solution to dry weight of the mixture is 0.03:1; the temperature of the first drying treatment is 120℃ and the time is 12h; the temperature of the first calcination treatment is 550℃ and the time is 4h.
[0048] S4. The catalyst support from step S3 is immersed in the impregnation solution, and then subjected to a second drying treatment and a second calcination treatment in sequence to obtain the catalyst product.
[0049] The impregnation solution was chloroplatinic acid; the mass ratio of platinum to catalyst support was 0.0035:1; the impregnation temperature was 30℃ and the time was 1h; the second drying treatment was at 120℃ and the time was 12h; the second calcination treatment was at 500℃ and the time was 2h.
[0050] The hydroisomerization catalyst prepared in Example 1 was cut into 50 nm thin slices and analyzed by TEM (transmission electron microscopy). The analysis results are as follows: Figure 1 As shown, due to the small thickness of the sample sheet and its high overall transmittance, the lighter-colored areas reveal the porous structure on the sheet. Typical porous dimensions were measured, as shown below. Figure 1 The diameter of the small pores is approximately 6 nm, the diameter of the large pores is approximately 15.7 nm, and the average diameter of the nanopores on the catalyst is 5–20 nm. The catalyst prepared in this embodiment can provide better diffusion channels, effectively increase the outer surface area, and expose more shape-selective pores. In isomerization reactions, this is beneficial for the isomerization of long-chain alkanes and reduces cracking reactions caused by long diffusion paths.
[0051] Example 2 The method of Example 1 is adopted, except that in step S1, the mass ratio of alkali to ZSM-48 molecular sieve powder in the alkaline solution is 2:10; the mass ratio of template agent to ZSM-48 molecular sieve powder is 0.8:10; in step S2, the temperature of the first crystallization treatment is room temperature (20°C) and the time is 1 hour; the temperature of the second crystallization treatment is 100°C and the time is 1 hour; the temperature of the third crystallization treatment is 170°C and the time is 20 hours.
[0052] Example 3 The method of Example 1 is adopted, except that in step S1, the mass ratio of alkali to ZSM-48 molecular sieve powder in the alkaline solution is 5:10; the mass ratio of template agent to ZSM-48 molecular sieve powder is 2:10; in step S2, the temperature of the first crystallization treatment is room temperature (20°C) and the time is 3h; the temperature of the second crystallization treatment is 80°C and the time is 3h; the temperature of the third crystallization treatment is 150°C and the time is 24h.
[0053] Example 4 The method of Example 1 is adopted, except that in step S1, the mass ratio of alkali to ZSM-48 molecular sieve powder in the alkaline solution is 0.01:10; the mass ratio of template agent to ZSM-48 molecular sieve powder is 0.01:10; in step S2, the temperature of the first crystallization treatment is 60°C and the time is 3h; the temperature of the second crystallization treatment is 150°C and the time is 3h; and the temperature of the third crystallization treatment is 180°C and the time is 6h.
[0054] Example 5 The method of Example 1 is used, except that the temperature of the first crystallization treatment is 20°C, the temperature of the second crystallization treatment is 80°C, and the temperature of the third crystallization treatment is 180°C.
[0055] Example 6 The method of Example 1 is used, except that the temperature of the first crystallization treatment is 20°C, the temperature of the second crystallization treatment is 140°C, and the temperature of the third crystallization treatment is 170°C.
[0056] Example 7 The method of Example 1 was used, except that the mass ratio of alkali to molecular sieve in the alkaline solution was 0.2:10.
[0057] Example 8 The method of Example 1 is used, except that the mass ratio of alkali to molecular sieve in the alkaline solution is 4:10.
[0058] Example 9 The method of Example 1 was used, except that the mass ratio of the template agent to the molecular sieve powder was 0.05:10.
[0059] Example 10 The method of Example 1 is used, except that the mass ratio of template agent to molecular sieve powder is 2:10.
[0060] Comparative Example 1 The method of Example 1 is used, except that no template agent is added in step S1.
[0061] Comparative Example 2 The method of Example 1 was used, except that the ZSM-48 molecular sieve was not treated with alkali.
[0062] Comparative Example 3 The method of Example 1 is used, except that in step S2, the crystallization temperature is 170°C and the time is 24 hours.
[0063] Comparative Example 4 The method of Example 1 is adopted, except that in step S2, the temperature of the first crystallization treatment is 25°C; the temperature of the second crystallization treatment is 155°C; and the temperature of the third crystallization treatment is 185°C.
[0064] Test case The hydroisomerization catalysts prepared in Examples 1-10 and Comparative Examples 1-4 were tested using the following methods: The nitrogen adsorption-desorption (BET) test was performed on a specific surface area and pore size analyzer (Micromeritics TriStar II 3020). Specific surface area and average pore size were calculated and statistically analyzed using the two-parameter BET equation, employing the N2 adsorption / desorption method at a test temperature of -196℃. Total pore volume, micropore volume, and mesopore volume were calculated using the t-plot method.
[0065] The testing method for hydroisomerization performance includes: placing the prepared hydroisomerization catalyst in a fixed bed, using n-hexadecane as raw material, with a hydrogen partial pressure of 1 MPa and a space velocity of 2.0 h⁻¹. -1 With a hydrogen-to-oil volume ratio of 500:1 and a reaction temperature of 250–320 °C, the isomerization performance of the catalyst was evaluated. The overall conversion rate and isohexadecane selectivity of the hydroisomerization products were calculated as follows: Conversion rate = ((mass of cracking products + mass of isohexadecane) / total mass of reaction products) × 100%; Isomer selectivity = (mass of isohexadecane / (mass of cracking products + mass of isohexadecane)) × 100%.
[0066] The results are shown in Table 1.
[0067] Table 1
[0068] As shown in Table 1, the method provided in this disclosure involves treating ZSM molecular sieves with an alkali followed by a three-stage crystallization process to obtain a modified ZSM molecular sieve. The active component is then loaded onto the modified ZSM molecular sieve to obtain a hydroisomerization catalyst. This disclosure effectively avoids the damage to the pore structure of the molecular sieve caused by conventional acid-base treatments, and achieves a high molecular sieve yield. Furthermore, the three-stage crystallization process directly introduces nanoscale pore structures into the molecular sieve crystals, effectively improving diffusion performance. The resulting modified ZSM molecular sieve exhibits a more uniform pore distribution and excellent isomer selectivity, providing sufficient active sites for the isomerization reaction of long-chain alkanes. This results in a hydroisomerization catalyst with excellent catalytic performance. Applying the hydroisomerization catalysts provided in Examples 1-10 of this disclosure to the hydroisomerization reaction of long-chain alkanes can effectively improve the isomer selectivity of the reaction.
[0069] Comparing Examples 5 and 6 with Example 1, it can be seen that controlling the temperature of the three-stage crystallization process within the preferred range of this application can further increase the specific surface area of the hydroisomer catalyst and the pore volume ratio with an average diameter of 5~20nm, so that the prepared hydroisomer catalyst has higher isomer selectivity.
[0070] Comparing Examples 7 and 8 with Example 1, it can be seen that controlling the mass ratio of alkali to molecular sieve in the alkaline solution within the preferred range of this application can control the specific surface area and the proportion of pore volume with an average diameter of 5-20 nm of the hydroisomerization catalyst within the preferred range, making the isomerization selectivity of the hydroisomerization catalyst more excellent, providing more active sites for the isomerization reaction of long-chain alkane, thereby further improving the isomerization selectivity of the reaction.
[0071] Comparing Examples 9 and 10 with Example 1, it can be seen that controlling the mass ratio of template agent to molecular sieve powder within the preferred range of this application can further improve the isomer selectivity of the hydroisomerization catalyst, provide more active sites for the isomerization reaction of long-chain alkane, and thus further improve the isomer selectivity of the reaction.
[0072] Comparing Comparative Example 1 with Example 1, it can be seen that since no template agent was added in Comparative Example 1, the specific surface area and micropore volume of the hydroisomerization catalyst were significantly reduced, and the proportion of pore volume with an average diameter of 5~20nm was too high, resulting in an uneven number and distribution of active sites, which led to a significantly lower isomer selectivity than in Examples 1~10.
[0073] Comparing Comparative Example 2 with Example 1, it can be seen that since the ZSM-48 molecular sieve was not treated with alkali in Comparative Example 2, the molecular sieve basically maintained its original microporous structure, which is not conducive to the formation of mesoporous structure. As a result, the micropore volume of the hydroisomerization catalyst is too large, the proportion of pore volume with an average diameter of 5~20nm is low, the pore channels are not well developed, the diffusion effect is poor, and the isomerization selectivity is poor.
[0074] Comparing Comparative Example 3 with Example 1, it can be seen that since only one stage of crystallization treatment was performed in Comparative Example 3, the pores of the hydroisomerization catalyst are not well developed, the diffusion performance is poor, and the isomerization selectivity is poor. It cannot provide sufficient active sites for the isomerization reaction of long-chain alkanes. When the hydroisomerization catalyst provided by Comparative Example 3 is applied to the hydroisomerization reaction of long-chain alkanes, the isomerization selectivity of the isomerization reaction is low.
[0075] Comparing Comparative Example 4 with Example 1, it can be seen that since the temperature of the three-stage crystallization treatment in Comparative Example 4 is not within the range specified in this application, it is not possible to effectively introduce nanoscale pore structures. The pore volume ratio with an average diameter of 5~20nm is low, and the specific surface area is low, resulting in poor diffusion performance and poor isomer selectivity. It cannot provide sufficient active sites for the isomerization reaction of long-chain alkane, resulting in isomer selectivity that is worse than that of Examples 1~10.
[0076] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0078] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A hydroisomerization catalyst, wherein, The hydroisomerization catalyst includes a catalyst support and an active component supported on the catalyst support; the catalyst support includes a modified ZSM molecular sieve and an inorganic oxide; the hydroisomerization catalyst includes a nanoporous structure with an average diameter of 5-20 nm. Based on the total mass of the hydroisomerization catalyst, the loading of the active component is 0.2~0.6 wt%.
2. The hydroisomerization catalyst according to claim 1, wherein, The ZSM molecular sieve includes one or more of ZSM-48 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, and ZSM-35 molecular sieve; the active component includes a Group VIII noble metal, which includes palladium and / or platinum. The inorganic oxide is selected from one or more of alumina, silicon oxide, and amorphous aluminum silicate.
3. The hydroisomerization catalyst according to claim 1, wherein, The nanopore structure is spherical, near-spherical, or near-ellipsoidal; The BET specific surface area of the hydroisomerization catalyst is 100~300 m². 2 / g; total pore volume is 0.25~0.35ml / g; micropore volume is 0.02~0.10ml / g; mesopore volume is 0.15~0.30ml / g; In the hydroisomerization catalyst, the pore volume with a diameter of 5-20 nm accounts for 60-90% of the total pore volume.
4. A method for preparing a hydroisomerization catalyst, wherein, The method includes: S1. The ZSM molecular sieve is alkali-treated, and then a template agent is added to obtain a mixed slurry; S2. The mixed slurry is subjected to a three-stage crystallization treatment to obtain a modified ZSM molecular sieve; S3. Mix the modified ZSM molecular sieve with a binder, and then perform molding, drying and first calcination to obtain a catalyst support. S4. Impregnate the catalyst support in an impregnation solution containing the active component to obtain the catalyst product; The alkaline treatment includes treating the molecular sieve with an alkaline solution; The three-stage crystallization process includes a first crystallization process, a second crystallization process, and a third crystallization process; the temperature of the first crystallization process is 20~60℃; the temperature of the second crystallization process is 60~150℃; and the temperature of the third crystallization process is 150~180℃.
5. The method according to claim 4, wherein, The alkaline solution comprises one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, and potassium carbonate; the concentration of the alkaline solution is 2 wt% or more; the ZSM molecular sieve comprises one or more of ZSM-48 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, and ZSM-35 molecular sieve; the template agent comprises an organic amine, preferably hexamethylammonium bromide and / or hexamethylenediamine; Optionally, the modified ZSM molecular sieve has a nanopore structure with a diameter of 5-20 nm; the modified ZSM molecular sieve has a BET specific surface area of 100-300 m². 2 / g; total pore volume is 0.20~0.30ml / g; micropore volume is 0.02~0.10ml / g, mesopore volume is 0.08~0.20ml / g; the modified ZSM molecular sieve has pores with an average diameter of 5~20nm accounting for 60~90% of the total pore volume; The mass ratio of alkali to molecular sieve in the alkaline solution is (0.01~5):10, preferably (0.5~2):10; The mass ratio of the template agent to the molecular sieve is (0.01~2):10, preferably (0.1~1):
10.
6. The method according to claim 4, wherein, The temperature of the second crystallization treatment is more than 50°C higher than the temperature of the first crystallization treatment; The temperature of the third crystallization treatment is more than 20°C higher than the temperature of the second crystallization treatment; The processing time for the first crystallization treatment is 0.5~10h; the processing time for the second crystallization treatment is 0.5~10h; and the processing time for the third crystallization treatment is 4~48h. The modified molecular sieve has a silicon-to-aluminum molar ratio of 50 to 200.
7. The method according to claim 4, wherein, The binder includes one or more of boehmite, alumina, alumina sol, silica sol, and silica. The dry weight ratio of the binder to the modified molecular sieve is (0.2~0.5):(0.5~0.8). Optionally, the molding process includes: acid treatment of the mixture of the modified molecular sieve and the binder, followed by kneading and molding to obtain agglomerated mixture, and extruding the agglomerated mixture into strips; The acid treatment conditions include: the acid solution includes one or more of nitric acid, citric acid, and oxalic acid; the mass ratio of the acid in the acid solution to the dry basis of the mixture is (0.01~0.05):1; Optionally, the temperature of the first drying treatment is 80~150℃ and the time is 5~24h; the temperature of the first calcination treatment is 500~600℃ and the time is 1~6h.
8. The method according to claim 4, wherein, The active component includes a compound of a Group VIII noble metal, which includes palladium and / or platinum; The mass ratio of the noble metal element in the active component to the catalyst support is (0.002~0.006):1; The immersion temperature is 0~50℃ and the time is 0.5~5h.
9. The hydroisomerization catalyst prepared by the method according to any one of claims 4 to 8.
10. Use of the hydroisomerization catalyst according to any one of claims 1 to 3 or 9 in the isomerization of long-chain alkanes; wherein, The long-chain alkane has 10 to 100 carbon atoms.