Method for preparing bridge type dihydrodicyclopentadiene by pretreating HUSY molecular sieve loaded Ni

Abstract

The invention discloses a method for preparing bridge dihydrodicyclopentadiene by pre-treating a HUSY molecular sieve loaded with Ni, which comprises the following steps: taking an acidified HUSY molecular sieve, calcining at a constant temperature of 400-600 DEG C for 5 hours, naturally cooling to 80 DEG C, and taking out; the method comprises the following steps: preparing a Ni (NO3) 2 aqueous solution by using deionized water according to 10% Ni loading capacity, carrying out equivalent-volume impregnation on a pretreated HUSY molecular sieve, stirring at 80 DEG C, heating until moisture is evaporated, drying at 120 DEG C for 5 hours, mashing and grinding into powder, calcining at 500 DEG C for 5 hours, and reducing for 4 hours under the conditions that the hydrogen flow rate is 40 mL / min and the temperature is 500 DEG C to obtain a Ni / HUSY catalyst; the preparation method comprises the following steps: dissolving a Ni / HUSY catalyst and dicyclopentadiene in a solvent according to a ratio of Ni / HUSY to dicyclopentadiene to the solvent of 0.15: 1: 5; stirring and reacting for 60-270 minutes under the conditions that the temperature is 110-200 DEG C and the hydrogen pressure is 2-4 MPa, collecting a product, and carrying out centrifugal separation, so as to obtain the bridge-type dihydrodicyclopentadiene. According to the invention, chain regulation of dealumination, strong interaction of metal and a carrier and Ni active passivation is realized, use of noble metal is avoided, polar and non-polar solvents are compatible, and the problem of excessive hydrogenation of a traditional Ni-based catalyst is solved.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a method for preparing bridged dihydrodicyclopentadiene by pretreating Ni-supported HUSY molecular sieves. Background Technology

[0002] Dicyclopentadiene (DCPD) is a key component in the C5 fraction of ethylene cracking byproducts. China, as a major global ethylene producer, is also a major supplier of DCPD. Market data shows that the global DCPD market size was approximately RMB 6.144 billion in 2023 and is projected to steadily grow to RMB 6.336 billion by 2029. How to transform DCPD into high-value-added products has become a research hotspot in the chemical industry. Among these, bridged dihydrodicyclopentadiene, as the core product of shallow hydrogenation of DCPD, is chemically reactive and has two key applications: first, it can be used to synthesize high-energy fuel tetrahydrotricyclopentadiene via the Diels-Alder reaction, meeting the high-end energy needs of aerospace and other industries; second, it can participate in the synthesis of various fine chemicals as a pharmaceutical intermediate, showing huge market potential. However, the DCPD molecule contains double bonds that readily undergo hydrogenation, making it prone to over-reaction during hydrogenation to form bridged tetrahydrodicyclopentadiene (endo-THDCPD), resulting in low selectivity for the target product, bridged dihydrodicyclopentadiene. Therefore, precisely controlling the depth of hydrogenation is the core technical challenge of this reaction.

[0003] Existing technologies for the hydrogenation of DCPD to prepare bridged dihydrodicyclopentadiene have many drawbacks and are difficult to meet the needs of industrial production. For example, Chinese invention patent CN113839736A discloses a catalyst for the preparation of dihydrodicyclopentadiene, its preparation method and application. This catalyst can achieve high feed conversion rate, target product selectivity and yield when used to prepare dihydrodicyclopentadiene; however, due to the extremely low single-atom metal loading, the catalyst has insufficient hydrogenation activity, and the reaction time is generally as long as 8-24 hours, and the production efficiency is far from meeting the requirements of continuous industrial production. For example, Chinese invention patent CN109569632B discloses a catalyst, preparation method, and application for preparing bridged tetrahydrodicyclopentadiene. This technical solution uses Ni as the active metal, γ-Al2O3 as the support, and adds metal additives, reacting at 80-120℃ and 1-3MPa. Even if its minimum yield reaches 93.8%, the product is always bridged tetrahydrodicyclopentadiene, a product of deep hydrogenation, which cannot achieve directional control of shallow hydrogenation and completely deviates from the preparation goal of bridged dihydrodicyclopentadiene.

[0004] To address the shortcomings of the existing technology, this invention proposes a method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves loaded with Ni. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing bridged dihydrodicyclopentadiene by pretreating Ni-supported HUSY molecular sieves, thereby solving the problems mentioned in the background art. To achieve the above objective, this invention provides the following technical solution: The first aspect of this invention provides a method for preparing bridged dihydrodicyclopentadiene by pretreating Ni-supported HUSY molecular sieves, comprising the following steps: Pretreatment of HUSY molecular sieve: Take acidified HUSY molecular sieve, calcine it at a constant temperature of 400-600℃ for 5 hours, and take it out after naturally cooling to 80℃; Ni-supported HUSY molecular sieve: Ni(NO3)2 aqueous solution was prepared with deionized water with a Ni loading of 10%, and the pretreated HUSY molecular sieve was impregnated with an equal volume. The solution was stirred and heated at 80℃ until the water evaporated, dried at 120℃ for 5h, crushed and ground into powder, calcined at 500℃ for 5h, and reduced at 500℃ for 4h under hydrogen flow rate of 40mL / min to obtain Ni / HUSY catalyst. DCPD hydrogenation reaction: Ni / HUSY catalyst and dicyclopentadiene are dissolved in a solvent, which can be any one of ethanol, methanol and cyclohexane, according to the ratio of Ni / HUSY:dicyclopentadiene:solvent = 0.15:1:5. The reaction is carried out under stirring at a temperature of 110-200℃ and a hydrogen pressure of 2-4MPa for 60-270 min. The product is collected and centrifuged to obtain a clear liquid containing bridged dihydrodicyclopentadiene.

[0006] Preferably, in the pretreatment step of HUSY molecular sieve, the calcination temperature is set to 400℃, 500℃, or 600℃.

[0007] Preferably, in the pretreatment step of HUSY molecular sieve and the step of loading Ni onto HUSY molecular sieve, the calcination process is carried out in a muffle furnace.

[0008] Preferably, the initial temperature of the muffle furnace is set to 50°C, the heating rate is 5°C / min, and the temperature is maintained at a constant temperature after reaching the set calcination temperature.

[0009] Preferably, in the HUSY molecular sieve loading Ni step, Ni(NO3)2 aqueous solution is impregnated by stirring at room temperature for 2 hours.

[0010] Preferably, the mass fraction of the dicyclopentadiene is 0.97.

[0011] Preferably, the reaction temperature in the DCPD hydrogenation reaction step is 170°C.

[0012] Preferably, in the DCPD hydrogenation reaction step, the hydrogen pressure is 3 MPa.

[0013] Preferably, in the DCPD hydrogenation reaction step, the stirring speed is 700 r / min.

[0014] A second aspect of the present invention provides a bridged dihydrodicyclopentadiene, characterized in that it is prepared by the method described above.

[0015] The beneficial effects of this invention are as follows: By directional calcining HUSY molecular sieves at 400-600℃, this invention achieves a chain-like regulation of "dealuminization → strong metal-support interaction (SMSI) → Ni active passivation", which not only solves the problem of excessive hydrogenation in traditional Ni-based catalysts, but also avoids the use of precious metals. At the same time, the pretreated HUSY molecular sieves form a microporous-mesoporous composite structure, which is compatible with both polar and non-polar solvents, significantly reducing costs and improving process flexibility. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method for preparing bridged dihydrodicyclopentadiene using Ni-supported pretreatment of HUSY molecular sieves according to the present invention.

[0017] Figure 2 This is a schematic diagram of the nitrogen adsorption-desorption experiment results of the present invention.

[0018] Figure 3 This is a schematic diagram of the pore size distribution test results of the present invention.

[0019] Figure 4 This is a schematic diagram of the X-ray diffraction experimental results of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In this invention, the term “and / or” as used in the specification and appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] like Figure 1 As shown, this application provides a method for preparing bridged dihydrodicyclopentadiene by pretreating Ni-supported HUSY molecular sieves. HUSY is an octahedral zeolite molecular sieve with octahedral zeolite cages formed by β-cages and hexagonal columnar cages. The interconnecting windows are twelve-membered rings, with an average effective pore size of 0.74 nm. This structure provides a large specific surface area and regular channels, which is beneficial for molecular diffusion and adsorption. The method includes the following steps: S1. Pretreatment of HUSY molecular sieve: Weigh an appropriate amount of acidified HUSY molecular sieve and place it in a muffle furnace for calcination. Set the initial temperature to 50℃ and the heating rate to 5℃ / min. Heat the product to the set target calcination temperature and maintain it at a constant temperature for 5 hours. The target calcination temperature is selected from the range of 400-600℃. After calcination, allow it to cool naturally to 80℃ and remove the product for later use.

[0023] In this step, high-temperature calcination can remove residual organic template agents and adsorbed moisture from the HUSY molecular sieve preparation process, while also promoting partial dealuminization of the molecular sieve framework to generate free Al species. When organic matter decomposes and escapes at high temperature, it will form new mesoporous channels inside the molecular sieve, optimize the pore structure, and provide space for subsequent raw material adsorption and product desorption.

[0024] S2. Preparation of Ni / HUSY catalyst by supporting Ni on HUSY molecular sieves: Preparation of impregnation solution: Prepare a Ni(NO3)2 aqueous solution with deionized water at a Ni loading of 10% (Ni to carrier mass ratio); Equal volume impregnation: The pretreated HUSY molecular sieve was added to an aqueous solution of Ni(NO3)2 and stirred at room temperature for 2 hours to ensure that Ni... 2+ Uniformly adsorbed onto the carrier surface; Drying treatment: Place the impregnated mixture in an 80°C environment and heat while stirring until the moisture is completely evaporated, then transfer it to an oven and dry at 120°C for 5 hours; Calcination and reduction: The dried solid was crushed and ground into powder, placed in a quartz beaker and placed in a muffle furnace, and heated to 500°C in air at a rate of 5°C / min. The powder was calcined at this temperature for 5 hours to decompose Ni(NO3)2 into NiO. After calcination, the powder was transferred to a reduction apparatus, hydrogen gas was introduced (flow rate 40 mL / min), and the powder was reduced at 500°C for 4 hours to reduce NiO to metallic Ni, finally yielding a blackish-gray Ni / HUSY catalyst.

[0025] In this step, the free Al species generated by the desorption of HUSY molecular sieve are pretreated and form a Ni-Al alloy phase with metallic Ni during the reduction process. The excessive hydrogenation activity of Ni is passivated through the formation mechanism of strong metal-support interaction (SMSI), and the hydrogenation depth is precisely controlled. This provides theoretical support for the activity difference of the subsequent shallow hydrogenation reaction of DCPD and avoids the formation of bridged tetrahydrodicyclopentadiene.

[0026] Preparation of bridged dihydrodicyclopentadiene by S3 and DCPD hydrogenation reaction: According to the mass ratio of Ni / HUSY:dicyclopentadiene:solvent = 0.15:1:5, Ni / HUSY catalyst and dicyclopentadiene are dissolved in solvent and added to the reaction vessel, wherein the mass fraction of dicyclopentadiene is 0.97, and the solvent is any one of ethanol, methanol and cyclohexane; after the reaction vessel is sealed, hydrogen gas is introduced to a pressure of 2-4 MPa, the temperature is raised to 110-200℃ and stirred at a stirring rate of 700 r / min for 60-270 min; after the reaction is completed, the product is collected into a sample bottle, and solid impurities of the catalyst are removed by centrifugation to obtain a clear liquid containing bridged dihydrodicyclopentadiene.

[0027] The technical solution of the present invention is further illustrated below through specific embodiments: Example 1: Pretreatment of HUSY molecular sieve (400℃) Weigh 4g of acidified HUSY molecular sieve and place it in a quartz beaker, then place it in a muffle furnace; set the initial temperature to 50℃, and increase the temperature at a rate of 5℃ / min until it reaches 400℃ after 70min; maintain the temperature at 400℃ for 5h; allow it to cool naturally to 80℃, then remove the pretreated HUSY molecular sieve for later use.

[0028] Example 2: Pretreatment of HUSY molecular sieve (500℃) Weigh 4g of acidified HUSY molecular sieve and place it in a quartz beaker, then place it in a muffle furnace; set the initial temperature to 50℃, and increase the temperature at a rate of 5℃ / min until it reaches 500℃ after 90min; maintain the temperature at 500℃ for 5h; allow it to cool naturally to 80℃, then remove the pretreated HUSY molecular sieve for later use.

[0029] Example 3: Pretreatment of HUSY molecular sieve (600℃) Weigh 4g of acidified HUSY molecular sieve and place it in a quartz beaker, then place it in a muffle furnace; set the initial temperature to 50℃, and increase the temperature at a rate of 5℃ / min until it reaches 600℃ after 110min; maintain the temperature at 600℃ for 5h; allow it to cool naturally to 80℃, then remove the pretreated HUSY molecular sieve for later use.

[0030] Example 4: Preparation of Ni / HUSY catalyst (pretreated support at 400℃) Take 20 mL of deionized water, add Ni(NO3)2 according to a 10% Ni loading, and stir until completely dissolved; add the HUSY molecular sieve pretreated in Example 1 to the impregnation solution and stir at room temperature for 2 h; stir at 80 °C to evaporate the water, and dry in an oven at 120 °C for 5 h; grind into powder after drying, heat to 500 °C in a muffle furnace at 5 °C / min, and calcine in air atmosphere for 5 h; introduce hydrogen (flow rate 40 mL / min) and reduce at 500 °C for 4 h to obtain Ni / HUSY catalyst (400 °C support).

[0031] Example 5: Preparation of Ni / HUSY catalyst (pretreated support at 500℃) Following the steps in Example 4, a Ni / HUSY catalyst (500℃ support) was prepared using the HUSY molecular sieve pretreated in Example 2 as a support.

[0032] Example 6: Preparation of Ni / HUSY catalyst (pretreated support at 600℃) Following the steps in Example 4, a Ni / HUSY catalyst (600℃ support) was prepared using the HUSY molecular sieve pretreated in Example 3 as a support.

[0033] Example 7: Effect of different pretreatment temperatures on hydrogenation performance (ethanol as solvent) The Ni / HUSY catalysts prepared in Examples 4-6 were subjected to DCPD hydrogenation reactions to prepare bridged dihydrodicyclopentadiene according to the following methods: According to the mass ratio of Ni / HUSY:dicyclopentadiene:ethanol solvent = 0.15:1:5, the following materials were weighed: 3g Ni / HUSY catalyst, 20g dicyclopentadiene (mass fraction 0.97), and 100g ethanol. The Ni / HUSY catalyst and dicyclopentadiene were dissolved in ethanol solvent and added to the reaction vessel, where the mass fraction of dicyclopentadiene was 0.97. After sealing the reaction vessel, the reaction conditions were set as follows: hydrogen pressure 3MPa, temperature 170℃, stirring speed 700r / min, and reaction time 90min. After the reaction, the product was collected into a sample bottle, and solid impurities of the catalyst were removed by centrifugation to obtain a clear liquid containing bridged dihydrodicyclopentadiene. The purity of the product was detected by gas chromatography, and the conversion rate, selectivity, and yield of the reaction were calculated. The detection results are shown in Table 1 below.

[0034] Table 1 - Effect of different pretreatment temperatures on hydrogenation performance Ni / HUSY catalyst Calcination temperature / °C DCPD conversion rate / % 5.6-DHDCPD yield / % endo-THDCPD yield / % Yield of other substances / % Example 4 400 100.0 76.4 19.8 3.8 Example 5 500 100.0 76.0 21.8 2.2 Example 6 600 100.0 81.3 16.7 2.0 Example 8: Effect of different hydrogen pressures on hydrogenation performance (500℃ supported catalyst, ethanol as solvent) The Ni / HUSY catalyst prepared in Example 5 was used to prepare bridged dihydrodicyclopentadiene by DCPD hydrogenation reaction according to the method in Example 7. The difference between this example and Example 7 is that the hydrogen pressure was set to 2MPa, 3MPa and 4MPa respectively for comparative experiments; the test results are shown in Table 2 below.

[0035] Table 2 - Results of the effect of different hydrogen pressures on hydrogenation performance

[0036] Example 9: Effect of different reaction temperatures on hydrogenation performance (500℃ supported catalyst, ethanol as solvent) The Ni / HUSY catalyst prepared in Example 5 was subjected to DCPD hydrogenation reaction to prepare bridged dihydrodicyclopentadiene according to the method in Example 7. The difference between this example and Example 7 is that the hydrogenation reaction temperature was set to 110℃, 130℃, 150℃, 170℃, and 190℃, and the reaction time was 270 min, respectively. Comparative experiments were conducted, and the test results are shown in Table 3 below.

[0037] Table 3 - Effect of different reaction temperatures on hydrogenation performance

[0038] Example 10: Effect of different solvents on hydrogenation performance (supported catalyst at 500℃) The Ni / HUSY catalyst prepared in Example 5 was used to prepare bridged dihydrodicyclopentadiene by DCPD hydrogenation reaction according to the method in Example 7. The difference between this example and Example 7 is that ethanol, methanol, and cyclohexane (100g each) were used as solvents, and the reaction time was 270min. Comparative experiments were conducted, and the results are shown in Table 4 below.

[0039] Table 4 - Results of the effect of different solvents on hydrogenation performance

[0040] Example 11: Effect of different reaction times on hydrogenation performance (500℃ supported catalyst, cyclohexane as solvent) The Ni / HUSY catalyst prepared in Example 5 was used to prepare bridged dihydrodicyclopentadiene by DCPD hydrogenation reaction according to the method in Example 7. The difference between this example and Example 7 is that the solvent was 100g of cyclohexane, the temperature was 130℃, and the reaction time was 60min, 90min, 180min, and 270min, respectively. Comparative experiments were conducted, and the test results are shown in Table 5 below.

[0041] Table 5 - Effect of different reaction times on hydrogenation performance Ni / HUSY catalyst solvent DCPD conversion rate / % 5.6-DHDCPD yield / % endo-THDCPD yield / % Yield of other substances / % Example 5 60 96.4 89.6 2 4.8 Example 5 90 99.1 92.1 6.2 0.8 Example 5 180 100.0 85.3 13.5 1.2 Example 5 270 100.0 76.0 21.8 2.2

[0042] Example 11: Test experiments of HUSY, HUSY-500℃, and Ni / 500℃-HUSY In this embodiment, the HUSY sample was directly obtained from the acidified HUSY molecular sieve powder without any calcination treatment and was placed in a desiccator for later use; the HUSY-500℃ sample was obtained from the HUSY molecular sieve pretreated in Example 2 of this application; the Ni / 500℃-HUSY sample was obtained from the Ni / -HUSY catalyst prepared in Example 5 of this application. The HUSY, HUSY-500℃, and Ni / 500℃-HUSY samples were subjected to the following physicochemical performance tests: (I) Nitrogen Adsorption-Desorption Experiment: A fully automated specific surface area and pore size analyzer was used. The specific surface area of ​​the samples was calculated according to the Brunauer-Emmett-Teller (BET) model. The pore size distribution and mesopore volume in the mesopore range (2-50 nm) were analyzed using the Barrett-Joyner-Halenda (BJH) model. The micropore volume was calculated using the t-plot method. The experimental results are as follows: Figure 2 As shown.

[0043] Experimental Results and Analysis: HUSY sample: The isotherm is a type IV isotherm with no obvious hysteresis loop, and the adsorption capacity increases slowly in the high P / P0 (0.8-1.0) range, indicating that the sample is mainly microporous with very little mesoporous content.

[0044] HUSY-500℃ sample: The isotherm is still type IV, but the hysteresis loop (type H4) is significantly broadened, and the adsorption capacity in the high P / P0 range is greatly increased, indicating that the calcination pretreatment converts some micropores into mesopores, and the proportion of mesopores increases significantly.

[0045] The Ni / 500℃-HUSY sample shows that the width of the isotherm hysteresis loop is slightly smaller than that of HUSY-500℃, and the adsorption capacity in the high P / P0 range has decreased. This is presumably due to the blocked mesoporous channels by the loaded Ni particles (or Ni-Al alloy clusters), but the overall pore structure still maintains that is dominated by mesopores.

[0046] (ii) Pore size distribution test: Similar to the nitrogen adsorption-desorption experiment, the pore size (D, nm) is plotted on the x-axis, and the pore volume increment (dV / dD, cm) is plotted on the y-axis. 3 Using (g•nm) as the ordinate, plot the pore size distribution of HUSY, HUSY-500℃, and Ni / 500℃-HUSY; calculate the average pore size (D_avg) of the samples, and compare and analyze the pore size change trends after pretreatment and Ni loading. Experimental results are as follows: Figure 3 As shown.

[0047] Analysis of experimental results: HUSY sample: The pore size distribution is concentrated in the range of 0.5-1.5 nm (micropore range), with no obvious mesopore peaks and an average pore size of about 0.74 nm.

[0048] HUSY-500℃ sample: The pore size distribution shows a "bimodal" characteristic. In addition to retaining some micropores (0.5-1.5nm), a new mesopore peak (concentrated at 5-20nm) is added, and the average pore size increases to 2.5-3.0nm. This indicates that the calcination pretreatment achieves the optimization of the pore structure by "converting micropores into mesopores", which confirms the regulatory effect of pretreatment on pore structure.

[0049] Ni / 500℃-HUSY sample: The mesopore peak shifted towards smaller pore sizes (concentrated in 3-15nm), and the average pore size decreased to 2.0-2.5nm, further verifying that Ni particles partially blocked the mesopores, but still maintained the mesopore structure, which can meet the diffusion requirements of DCPD (molecular dynamic diameter of about 0.6nm) and bridged dihydrodicyclopentadiene (molecular dynamic diameter of about 0.65nm).

[0050] (III) X-ray diffraction experiment: Using an X-ray diffractometer, the characteristic diffraction peaks of HUSY and HUSY-500℃ (2θ≈15.5°, 20.8°, 23.7°, 27.2°, corresponding to the HUSY molecular sieve framework) were compared to analyze the effect of pretreatment on the molecular sieve crystal structure; the characteristic diffraction peak of Ni in the Ni / 500℃-HUSY sample was observed in particular: the characteristic peak of pure Ni is 2θ≈44.5° (PDF#04-0850), if a Ni-Al alloy (such as Ni) is formed... 0.92 Al 0.08 The characteristic peak will shift towards the higher 2θ direction (corresponding to PDF#04-007-0401). The alloying reaction caused by the SMSI effect is verified by the peak position shift. Experimental results are as follows: Figure 4 As shown.

[0051] Analysis of experimental results: Molecular sieve framework structure: The characteristic diffraction peak intensities of HUSY and HUSY-500℃ are basically the same, with no obvious broadening or disappearance, indicating that calcination at 500℃ did not destroy the crystal structure of HUSY, but only removed the organic template agent and some framework Al.

[0052] Phase changes of Ni: In Ni / HUSY samples directly loaded with Ni (using untreated HUSY as the support), a distinct characteristic peak of pure Ni (2θ≈44.5°) can be observed; however, in Ni / 500℃-HUSY samples, this peak shifts to 2θ≈44.8°-45.0°, and the peak intensity weakens, corresponding to Ni... 0.92 Al 0.08 The characteristic peaks of the alloy (PDF#04-007-0401) prove that the free Al desorbed at HUSY-500℃ undergoes an alloying reaction with Ni, forming the SMSI effect and passivating the hydrogenation activity of Ni.

[0053] (iv) Statistical experiments on specific surface area, pore volume, and pore size: Based on the specific surface area, micropore volume, and mesopore volume data obtained from the nitrogen adsorption-desorption experiment, combined with the average pore size results from the pore size distribution test, statistical analysis was performed. The experimental results are shown in Table 6 below.

[0054] Table 6 - Statistical Results of Specific Surface Area, Pore Volume and Pore Diameter sample <![CDATA[Specific surface area ( 2 / g)]]> <![CDATA[Micropore volume (cm 3 / g)]]> <![CDATA[Mesopore volume (cm 3 / g)]]> Aperture (nm) HUSY-500℃ 446.8641 0.1597 0.2485 2.2244 HUSY 680.5242 0.244 0.3344 1.9655 Ni / 500℃-HUSY 564.3506 0.2069 0.2789 1.9768 Analysis of experimental results: After pretreatment (HUSY→HUSY-500℃): the specific surface area decreased by about 15%-20%, the micropore volume decreased by about 35%-40%, and the mesopore volume increased by 4-5 times. This proves that calcination removes the organic template agent and induces the transformation of micropores into mesopores. At the same time, dealuminization causes some micropores to collapse, resulting in a slight decrease in the total specific surface area.

[0055] After loading with Ni (HUSY-500℃→Ni / 500℃-HUSY): the specific surface area further decreases by about 10%, and the mesopore volume decreases by about 25%-30%, mainly due to Ni particles blocking the mesopore channels. However, the mesopore volume is still significantly higher than that of untreated HUSY, ensuring the diffusion efficiency of raw materials and products.

[0056] Based on the analysis of the above embodiments, the beneficial effects of the present invention are as follows: (1) The pretreated HUSY molecular sieve forms a microporous-mesoporous composite structure, which can effectively realize the "microporous to mesoporous" transformation of HUSY molecular sieve. The mesoporous volume is greatly increased and the average pore size is increased, which verifies the regulatory effect of HUSY directional pretreatment on pore structure. It provides sufficient space for DCPD adsorption and bridged dihydrodicyclopentadiene desorption, and solves the problem of low mass transfer efficiency of traditional microporous molecular sieves. It is also compatible with ethanol, methanol (polar) and cyclohexane (nonpolar) solvents, which solves the problem of solvent limitation in the existing technology, adapts to the solvent inventory of different production scenarios, and improves process flexibility. (2) The catalyst raw material is only non-precious metal Ni. A Ni loading of 10wt% can achieve a selectivity of >90% for bridged dihydrodicyclopentadiene, avoiding the high cost of precious metals. The cost is only more than 1 / 20 of that of Pd-based catalysts. There is no need to add additional hydrogen donors, and low-cost non-polar solvents (such as cyclohexane, which has a lower unit price than isopropanol) can be used, resulting in a significant reduction in overall cost. In addition, the catalyst preparation does not require complex stepwise impregnation, the reaction conditions are mild (temperature 110-200℃, pressure 2-4MPa), the equipment requirements are low, and it is easy to scale up production. (3) The free Al desorbed at HUSY-500℃ undergoes an alloying reaction with Ni to form a Ni-Al alloy phase, confirming the SMSI effect; Ni / 500℃-HUSY retains the optimized mesoporous structure and SMSI effect, taking into account both mass transfer efficiency and hydrogenation activity regulation: the excessive hydrogenation activity of Ni can be passivated through the SMSI effect, providing a core guarantee for the precise control of shallow hydrogenation of DCPD; and the hydrogenation reaction at 110-200℃ and 2-4MPa requires only 60-270min, which is much shorter than the 8-24h of patent CN113839736A, greatly improving production efficiency.

[0057] In summary, this invention achieves a chain-like regulation of "dealuminization → strong metal-support interaction (SMSI) → Ni active passivation" by directional calcining of HUSY molecular sieves at 400-600℃. This solves the problem of excessive hydrogenation in traditional Ni-based catalysts and avoids the use of precious metals. At the same time, the pretreated HUSY molecular sieves form a microporous-mesoporous composite structure that is compatible with both polar and non-polar solvents, significantly reducing costs and improving process flexibility.

[0058] Regarding the embodiments of the present invention, it should also be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. The scope of protection of the present invention should be determined by the scope of the claims. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing bridged dihydrodicyclopentadiene by pretreating Ni-supported HUSY molecular sieves, characterized in that, Includes the following steps: Pretreatment of HUSY molecular sieve: Take acidified HUSY molecular sieve, calcine it at a constant temperature of 400-600℃ for 5 hours, and take it out after naturally cooling to 80℃; Ni-supported HUSY molecular sieve: Ni(NO3)2 aqueous solution was prepared with deionized water with a Ni loading of 10%, and the pretreated HUSY molecular sieve was impregnated with an equal volume. The solution was stirred and heated at 80℃ until the water evaporated, dried at 120℃ for 5h, crushed and ground into powder, calcined at 500℃ for 5h, and reduced at 500℃ for 4h under hydrogen flow rate of 40mL / min to obtain Ni / HUSY catalyst. DCPD hydrogenation reaction: Ni / HUSY catalyst and dicyclopentadiene are dissolved in a solvent, which can be any one of ethanol, methanol and cyclohexane, according to the ratio of Ni / HUSY:dicyclopentadiene:solvent = 0.15:1:

5. The reaction is carried out under stirring at a temperature of 110-200℃ and a hydrogen pressure of 2-4MPa for 60-270 min. The product is collected and centrifuged to obtain a clear liquid containing bridged dihydrodicyclopentadiene.

2. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 1, characterized in that, In the pretreatment step of HUSY molecular sieve, the calcination temperature is set to 400℃, 500℃, or 600℃.

3. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 1, characterized in that, In the pretreatment step of HUSY molecular sieve and the step of loading Ni onto HUSY molecular sieve, the calcination process is carried out in a muffle furnace.

4. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 4, characterized in that, The initial temperature of the muffle furnace is set to 50℃, the heating rate is 5℃ / min, and the temperature is maintained at a constant temperature after reaching the set calcination temperature.

5. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 1, characterized in that, In the HUSY molecular sieve loading Ni step, Ni(NO3)2 aqueous solution is stirred at room temperature for 2 hours for impregnation.

6. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 1, characterized in that, The mass fraction of the dicyclopentadiene is 0.

97.

7. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 1, characterized in that, In the DCPD hydrogenation reaction step, the reaction temperature is 170°C.

8. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 1, characterized in that, In the DCPD hydrogenation reaction step, the hydrogen pressure is 3 MPa.

9. The method for preparing bridged dihydrodicyclopentadiene by pretreating HUSY molecular sieves with Ni according to claim 1, characterized in that, In the DCPD hydrogenation reaction step, the stirring speed is 700 r / min.

10. A bridged dihydrodicyclopentadiene, characterized in that, It is prepared by the method described in any one of claims 1 to 9.

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