Preparation method and application of high-dispersion Ni-TON type molecular sieve
By optimizing process parameters and the timing of nickel source introduction, high dispersion of Ni-TON molecular sieves was achieved, solving the dispersion and stability problems of nickel species in TON-type molecular sieves, and obtaining a highly efficient catalyst for the hydrogenation reaction of hydrocarbon-based biodiesel.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG QILU HUAXIN HIGH TECH
- Filing Date
- 2026-01-29
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies make it difficult to achieve uniform dispersion and stable anchoring of nickel species when preparing TON-type molecular sieves, resulting in a decrease in catalytic activity and stability. Furthermore, traditional methods may damage the molecular sieve structure or affect the purity of the crystal phase.
By optimizing process parameters, especially controlling the timing and time window of introducing mineralizer and nickel source, a TON framework is formed first and then the nickel source is introduced. Combined with acidic exchange conditions, high dispersion of nickel species inside the molecular sieve channels is achieved.
Highly crystalline Ni-TON molecular sieves were prepared, exhibiting high conversion rate and excellent isomerization ability, which improved the low-temperature flow properties of bio-jet fuel. The process is reliable and environmentally friendly.
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Figure CN122124855A_ABST
Abstract
Description
Technical Field
[0001] This invention specifically relates to a method for preparing and applying a highly dispersed Ni-TON molecular sieve, belonging to the technical field of molecular sieve material preparation and catalytic application. Background Technology
[0002] TON-type molecular sieves are aluminosilicate crystals with a one-dimensional ten-membered ring straight-channel structure. Due to their unique shape-selective catalytic properties and good hydrothermal stability, they show broad application prospects in petrochemical processes such as catalytic cracking, hydrocracking, and isomerization. By introducing transition metal nickel to modify TON molecular sieves, they can be endowed with excellent hydrogenation activity and a certain isomerization ability, thereby expanding their applications in the field of clean energy.
[0003] Currently, common methods for preparing nickel-modified TON molecular sieves mainly include post-synthetic modification methods (such as impregnation and ion exchange) and in-situ hydrothermal synthesis. However, these methods all have significant limitations when applied to TON structures:
[0004] 1. Post-modification method: such as the equal volume impregnation method, although simple to operate, the nickel species are mainly loaded on the outer surface of the molecular sieve and the pore inlet, making it difficult to achieve uniform dispersion. During subsequent calcination and reaction, they are prone to migrate and aggregate to form large particles, which block the pores and lead to a rapid decline in catalytic activity and stability.
[0005] 2. Traditional in-situ hydrothermal synthesis method: Introducing nickel source directly in the early stage of gel synthesis can cause nickel ions to seriously interfere with the ordered assembly and crystallization process of silicon and aluminum species, often resulting in impure TON crystal phase and low crystallinity, which cannot simultaneously ensure the integrity of molecular sieve structure and efficient introduction of metal.
[0006] 3. Improved in-situ synthesis methods: such as ammonia stripping or high-pH aging, while achieving some progress in nickel modification of other molecular sieves (e.g., ZSM-5, Beta), present compatibility issues when applied to the TON system, which is extremely sensitive to synthesis conditions. For example, high alkalinity environments can easily disrupt the gel microenvironment required for TON structure orientation, while ammonium ions introduced during ammonia stripping may interfere with the guiding effect of the 1,6-hexanediamine template agent, leading to crystallization failure or unsatisfactory nickel dispersion.
[0007] Therefore, there is an urgent need in this field to develop a new method for nickel modification of TON-type molecular sieves that can achieve high dispersion and stable anchoring of nickel species in the molecular sieve framework without sacrificing the crystallinity of the molecular sieve, thereby obtaining a high-performance catalyst with both excellent hydrogenation activity and isomerization selectivity. Summary of the Invention
[0008] The purpose of this invention
[0009] The primary objective of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing highly dispersed Ni-TON molecular sieves. This method achieves high dispersion of nickel species in TON molecular sieves through the optimized combination of a series of key process parameters, particularly by controlling the timing of the introduction of the mineralizer and the nickel source.
[0010] Another object of the present invention is to provide the application of the above-mentioned highly dispersed Ni-TON molecular sieve in the catalytic production of biojet fuel from hydrocarbon-based biodiesel hydrogenation, wherein the molecular sieve exhibits excellent catalytic activity and isomerization selectivity in this specific reaction.
[0011] Technical solution of the present invention
[0012] To achieve the above objectives, the present invention adopts the following technical solution:
[0013] A method for preparing a highly dispersed Ni-TON molecular sieve, comprising the following steps:
[0014] (1) Mix water, an alkaline source and potassium fluoride as a mineralizing agent to obtain a mineralizing agent solution;
[0015] (2) The silicon source, aluminum source, alkali source, template agent 1,6-hexanediamine and water are thoroughly mixed in a molar ratio of 1:(0.007~0.015):(0.04~0.12):(0.25~0.40):(20~40) and aged at 40~60℃ for 3 hours to obtain the initial gel;
[0016] (3) Add the mineralizing agent solution obtained in step (1) to the initial gel in step (2), the amount added is 2.0%~4.0% of the mass of the initial gel; after mixing for 10~30 minutes, add nickel nitrate accounting for 7%~10% of the mass of the initial gel as a nickel source, and mix evenly;
[0017] (4) The mixture obtained in step (3) is transferred to a reaction vessel and crystallized at 150~170℃ for 10~20 hours. After the reaction is completed, it is cooled, filtered, washed, dried, and calcined at 600~650℃ for 4~6 hours to obtain Ni-TON molecular sieve precursor.
[0018] (5) The precursor obtained in step (4) is subjected to ion exchange in a nitric acid solution with a molar concentration of 1.0~3.0 mol / L at 80~90℃ for 0.5~1 hours, and the mass ratio of the precursor to the nitric acid solution is 1:(10~20); after the exchange is completed, the precursor is filtered, washed and dried to obtain the highly dispersed Ni-TON molecular sieve.
[0019] In the Ni-TON molecular sieve prepared by the method, nickel species exist in the form of NiO. Through in-situ synthesis and post-processing, they undergo strong chemical interactions with the silanol groups, defect sites, or residual anions (such as F⁻) of the molecular sieve framework, and are dispersed inside the channels and near the pore openings, forming highly dispersed supported nickel oxide (NiO) active centers that have strong interactions with the TON molecular sieve support.
[0020] Preferably, water, an alkali source, and potassium fluoride as a mineralizing agent are mixed in a mass ratio of 10:(0.5~1):(0.25~0.5) to obtain a mineralizing agent solution.
[0021] Preferably, in step (3), the amount of the mineralizing agent solution added is 2.5% to 3.5% of the initial gel mass.
[0022] Preferably, in step (3), the amount of nickel nitrate added is 8% to 9% of the initial gel mass.
[0023] Preferably, in step (3), the mixing time is 15 to 25 minutes.
[0024] Preferably, in step (5), the molar concentration of the nitric acid solution is 1.5~2.5 mol / L.
[0025] The highly dispersed Ni-TON molecular sieve can be used as a catalyst in the catalytic hydrogenation of hydrocarbon-based biodiesel to produce biojet fuel. Preferably, the process parameters for the catalytic reaction are: reaction temperature 270-290℃ (preferably 280℃), hydrogen pressure 3-5 MPa (preferably 4 MPa), hydrogen to hydrocarbon-based biodiesel volume ratio (hydrogen-to-oil ratio) 800-1200 (preferably 1000), and mass hourly space velocity (WHSV) 1.5-2.5 h⁻¹. -1 (Preferred 2.0 h) -1 ).
[0026] Beneficial effects of the present invention
[0027] 1. Innovative Process Design: This invention creatively designs an introduction sequence of "gel first, then mineralizer, then nickel source," and discovers a "critical time window" of 10-30 minutes after the mineralizer is mixed with the gel, which achieves optimal dispersion. This process ensures that the TON framework forms stably first, followed by the potassium fluoride mineralizer moderately modifying the gel and providing temporary anchoring points for nickel ions. Finally, the introduced nickel source is highly dispersed within a confined space, avoiding interference with crystallization or later agglomeration of nickel in traditional methods.
[0028] 2. Highly dispersed nickel species: Through the above-mentioned specific process, combined with subsequent optimized acid exchange conditions, high dispersion of nickel species was successfully achieved, greatly exposing the active sites.
[0029] 3. Synergistic catalytic performance: The obtained Ni-TON molecular sieve has both a highly crystalline TON framework structure (providing shape-selective and acidic sites) and highly dispersed nickel hydrogenation centers. The two work synergistically to not only exhibit high conversion rate (>99%) in the hydrogenation reaction of hydrocarbon-based biodiesel, but also show excellent isomerization ability (isoalkanes / n-alkanes ratio >2.5), which significantly improves the low-temperature flow properties of biojet fuel.
[0030] 4. Reliable and green process: The entire preparation process has clear steps, mild and controllable conditions, and the raw materials used are inexpensive and readily available. It does not require the use of expensive organic ligands or toxic reagents, has good reproducibility, and is suitable for large-scale production. Attached Figure Description
[0031] Figure 1 This is the X-ray diffraction (XRD) pattern of the highly dispersed Ni-TON molecular sieve prepared in Example 1 of this invention. Detailed Implementation
[0032] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.
[0033] Example 1
[0034] (1) Preparation of mineralizing agent solution: Mix 10g of deionized water, 0.5g of sodium hydroxide and 0.25g of potassium fluoride in a beaker and set aside.
[0035] (2) Preparation of initial gel: In another beaker, silica sol equivalent to 1 mol SiO2, 0.01 mol aluminum sulfate, 0.08 mol sodium hydroxide, 0.30 mol 1,6-hexanediamine and 30 mol water are mixed and aged in a water bath at 50℃ for 3 hours to obtain a uniform initial gel.
[0036] (3) Introduction of nickel source and crystallization: All the mineralizing agent solution from step (1) (approximately 2.0% of the initial gel mass) was added to the initial gel from step (2), and stirred continuously at 50°C for 20 minutes. Then, nickel nitrate equivalent to 8% of the initial gel mass was added, stirred evenly, and transferred to a 100 mL polytetrafluoroethylene-lined reactor, and crystallized at 160°C for 15 hours. After cooling, the product was filtered, washed, dried at 110°C overnight, and then calcined in a muffle furnace at 620°C for 5 hours to obtain the Ni-TON molecular sieve precursor.
[0037] (4) Ion exchange: 5g of the precursor was dispersed in 75g of 2.0 mol / L nitric acid solution (mass ratio 1:15), and exchanged at 85℃ for 45 minutes. After filtration, washing and drying, highly dispersed Ni-TON molecular sieve A was obtained.
[0038] Example 2
[0039] (1) Mix 10g of deionized water, 1.0g of potassium hydroxide and 0.5g of potassium fluoride evenly to obtain a mineralizing agent solution.
[0040] (2) Preparation of initial gel: Mix 1 mol of tetraethyl orthosilicate (TEOS), 0.015 mol of aluminum sulfate, 0.12 mol of sodium hydroxide, 0.40 mol of 1,6-hexanediamine and 40 mol of water, and age at 60°C with constant stirring for 3 hours.
[0041] (3) Add the mineralizing agent solution from step (1) (4.0% of the gel mass), stir continuously at 55°C for 10 minutes, then add nickel nitrate (10% of the gel mass), mix, and crystallize at 150°C for 20 hours. After cooling, filter, wash, dry at 110°C overnight, and then calcine in a muffle furnace at 650°C for 4 hours to obtain the Ni-TON molecular sieve precursor.
[0042] (4) The precursor was placed in a 1.0 mol / L nitric acid solution (mass ratio of precursor to nitric acid solution 1:20) and exchanged at 90℃ for 30 minutes. After treatment, highly dispersed Ni-TON molecular sieve B was obtained.
[0043] Example 3
[0044] (1) Mix 10g of deionized water, 0.7g of sodium hydroxide and 0.35g of potassium fluoride evenly to obtain a mineralizing agent solution.
[0045] (2) Preparation of initial gel: Mix 1 mol SiO2 equivalent of silica (C silicon), 0.007 mol aluminum sulfate, 0.04 mol sodium hydroxide, 0.25 mol 1,6-hexanediamine and 20 mol water, and age at 40°C with constant stirring for 3 hours.
[0046] (3) Add the mineralizing agent solution (3.0% of the gel mass) from step (1) to the gel from step (2), stir continuously at 45°C for 30 minutes, then add nickel nitrate (7.0% of the gel mass), mix evenly, transfer to a reactor, and crystallize at 170°C for 10 hours. After cooling, filter, wash, dry at 110°C overnight, and then calcine in a muffle furnace at 600°C for 6 hours to obtain the Ni-TON molecular sieve precursor.
[0047] (4) The precursor was placed in a 3.0 mol / L nitric acid solution (the mass ratio of the precursor to the nitric acid solution was 1:10) and exchanged at 80°C for 60 minutes to obtain highly dispersed Ni-TON molecular sieve C.
[0048] Comparative Example 1 (Immersion Method)
[0049] Following the method in Example 1, an H-TON type molecular sieve without introducing a nickel source was first prepared. Then, it was impregnated with an equal volume of nickel nitrate solution to make the Ni loading equivalent to that in Example 1. After drying and calcination at 620°C for 5 hours, a Ni / H-TON catalyst was obtained.
[0050] Comparative Example 2 (Traditional One-Pot Method)
[0051] The nickel source (nickel nitrate, with the same amount of Ni as in Example 1) was added directly during the preparation of the initial gel in step (2), and the remaining steps were the same as in Example 1. The resulting product was denoted as Ni-TON (one-pot method).
[0052] Comparative Example 3 (Critical Timing Deviation: Immediate Nickel Addition)
[0053] The steps are exactly the same as in Example 1, except that in step (3), nickel nitrate is added immediately after the mineralizing agent solution is added (the mixing time is recorded as 0 minutes), and the resulting product is recorded as Ni-TON (nickel added immediately).
[0054] Comparative Example 4 (Critical Timing Deviation: Nickel Added Too Late)
[0055] The steps are exactly the same as in Example 1, except that in step (3), after adding the mineralizing agent solution and stirring for 60 minutes, nickel nitrate is added, and the resulting product is recorded as Ni-TON (nickel added too late).
[0056] Application effect evaluation experiment
[0057] The catalysts obtained in Examples 1-3 and Comparative Examples 1-4 were used for the hydrogenation reaction of hydrocarbon-based biodiesel. The reaction was carried out in a fixed-bed microreactor under the following conditions: temperature 280°C, hydrogen pressure 4 MPa, hydrogen-to-oil ratio 1000, and mass hourly space velocity 2.0 h⁻¹. -1 Samples were taken for analysis 2 hours after the reaction stabilized. The results are shown in the table below:
[0058]
[0059] Table 1 Application Performance of Each Embodiment and Comparative Example
[0060] Results analysis:
[0061] The results above show that, through strict control of process parameters, especially the "critical time window" (10-30 minutes) for the introduction of the mineralizer and nickel source, Examples 1-3 of this invention successfully prepared Ni-TON molecular sieves with highly dispersed NiO. These sieves exhibited near-complete conversion and the highest isomerization performance in the catalytic reaction.
[0062] Comparative Examples 3 and 4 demonstrate that deviating from the "critical time window" described in this invention significantly reduces both the dispersion and catalytic performance of nickel. A comparison with Comparative Examples 1 (impregnation method) and 2 (one-pot method) further highlights the synergistic effect and significant technological advancements resulting from the overall process combination of this invention.
Claims
1. A method for preparing a highly dispersed Ni-TON type molecular sieve, characterized in that, The molecular sieve is prepared by a method comprising the following steps: (1) Mix water, an alkaline source and potassium fluoride as a mineralizing agent to obtain a mineralizing agent solution; (2) The silicon source, aluminum source, alkali source, template agent 1,6-hexanediamine and water are thoroughly mixed in a molar ratio of 1:(0.007~0.015):(0.04~0.12):(0.25~0.40):(20~40) and aged at 40~60℃ for 3 hours to obtain the initial gel; (3) Add the mineralizing agent solution obtained in step (1) to the initial gel in step (2), the amount of which is 2.0% to 4.0% of the mass of the initial gel; after mixing for 10 to 30 minutes, add nickel nitrate accounting for 7% to 10% of the mass of the initial gel as a nickel source, and mix evenly; (4) The mixture obtained in step (3) is transferred to a reaction vessel and crystallized at 150~170℃ for 10~20 hours; after the reaction is completed, it is cooled, filtered, washed, dried and calcined to obtain Ni-TON molecular sieve precursor; (5) The precursor obtained in step (4) is subjected to ion exchange in a nitric acid solution with a molar concentration of 1.0~3.0 mol / L at 80~90℃ for 0.5~1 hours, and the mass ratio of the precursor to the nitric acid solution is 1:(10~20); after the exchange is completed, it is filtered, washed and dried to obtain the highly dispersed Ni-TON molecular sieve; wherein, in the Ni-TON molecular sieve prepared by the method, the nickel species are mainly NiO distributed in the form of a load inside the pores and near the pore openings.
2. The method for preparing a highly dispersed Ni-TON molecular sieve according to claim 1, characterized in that, In step (1), the mass ratio of water, alkali source and potassium fluoride is 10 : (0.5~1) : (0.25~0.5).
3. The method for preparing a highly dispersed Ni-TON molecular sieve according to claim 1, characterized in that, In step (4), the roasting is carried out at 600~650℃ for 4~6 hours.
4. The method for preparing a highly dispersed Ni-TON molecular sieve according to claim 1, characterized in that, In step (5), the molar concentration of the nitric acid solution is 1.5~2.5 mol / L.
5. An application of a highly dispersed Ni-TON molecular sieve, characterized in that, The highly dispersed Ni-TON molecular sieve is used as a catalyst in the catalytic hydrogenation of hydrocarbon-based biodiesel to produce biojet fuel.