A nickel-based catalyst for deep hydrogenation of DCPD resin and a preparation method thereof

Abstract

The present application relates to the technical field of catalyst preparation and application, and relates to a nickel-based catalyst for preparing hydrogenated DCPD resin by deeply hydrogenating DCPD resin and a preparation method thereof.The nickel-based catalyst comprises 40-60% of active component nickel (Ni), 35-60% of hierarchical pore carrier and 1-5% of electronic auxiliary yttrium (Y). The nickel-based catalyst is prepared by the synergy of the three of the construction of the hierarchical pore carrier, the modification of the electronic auxiliary (Y) and the surface treatment of citric acid, and highly dispersed active components are realized by a precipitation method. The DCPD resin deeply hydrogenated by the nickel-based catalyst has higher reaction activity, better stability and more excellent anti-coking capacity compared with traditional technology.

Description

Technical Field

[0001] This invention belongs to the field of catalyst materials technology, specifically relating to a nickel-based catalyst for deep hydrogenation of dicyclopentadiene (DCPD, hereinafter referred to as such) resin and its preparation method. Background Technology

[0002] Hydrogenated DCPD resin is widely used in adhesives, coatings, and rubber tackifiers due to its excellent weather resistance, thermal stability, light color, and good compatibility. The hydrogenation process of DCPD resin involves saturating the unsaturated double bonds in its molecules, which requires a catalyst in a high-temperature, high-pressure hydrogen environment. Currently, the commonly used hydrogenation catalysts in industry are mainly noble metal catalysts (such as Pd and Pt). Although they have high activity and good selectivity, they are expensive and scarce, leading to high production costs. Nickel-based catalysts, as non-noble metal catalysts, are inexpensive and have the potential to replace noble metal catalysts. However, traditional nickel-based catalysts face the following key technical challenges in the hydrogenation application of DCPD resin: DCPD fused ring hydrogenation is difficult because ordinary catalysts have limited activation capacity for hydrogen and cannot efficiently break the high-energy double bonds in the fused ring structure, resulting in insufficient hydrogenation depth and difficulty in meeting product color (APHA) and bromine value standards.

[0003] DCPD molecules have a large molecular dynamic diameter (≥1.2nm), while the small pore size (<10nm) of traditional catalysts leads to low mass transfer efficiency of reactants / products and slow diffusion within the catalyst channels.

[0004] The catalyst has a short lifespan and poor stability. During the reaction, the gum and trace heteroatoms (S, O) in the resin are prone to coking or adsorption on the catalyst surface, which leads to the active sites being covered and the catalyst being rapidly deactivated.

[0005] Chinese patent application CN115703067B discloses a method for preparing a porous supported Ni / Ni3ZnC0.7 catalyst. This catalyst supports Ni particles and Ni3ZnC0.7 nanoparticles, ensuring good ion and electron transport, and serves as an excellent hydrogenation catalyst. This catalyst exhibits good catalytic activity for the hydrogenation of dicyclopentadiene to bridged tetrahydrodicyclopentadiene. Although it discloses abundant pores, the specific structure of the pores is not revealed. Patent CN108262047A discloses a method for preparing Ni-Mo supported on a specific carrier, nickel-containing boehmite. The advantage of this hydrogenation catalyst lies in its ability to organically combine nickel and boehmite, effectively dispersing the active component nickel within the boehmite and forming a nickel-containing alumina support with a specific crystal structure. It also effectively regulates the pore structure and acidity of the support, resulting in a catalyst with high hydrogenation activity. Patent CN116273015A provides a method for preparing a Ni-Zn-Mg supported petroleum resin hydrogenation catalyst. The catalyst includes an active component and a support. The active component is nickel, zinc, and magnesium, and the support is an alumina support. Nickel and magnesium are uniformly distributed on the surface of the alumina support, maintaining the activity of nickel. The stability of the microstructure of the active sites on the alumina support is improved. The addition and content of magnesium improve the pH of the petroleum resin hydrogenation catalyst surface, thereby enhancing the hydrogenation activity and selectivity of the catalyst and reducing the occurrence of hydrogenation degradation side reactions. It is mentioned that the support should have bimodal or multimodal pores, with micropores around 10-30 nm and macropores around 100 nm. However, the ratio of micropores to macropores is not disclosed. If the proportion of micropores is too high, the proportion of macropore channels will be insufficient, making it difficult for large petroleum resin molecules to diffuse to the active sites within the micropores, thus limiting the reaction rate. Simultaneously, product molecules are prone to retention within the micropores, leading to over-hydrogenation. Side reactions such as hydrogenation and degradation can lead to several problems. If the proportion of macropores is too high, the specific surface area of ​​the support will decrease significantly, the loading and dispersion of the active component Ni will decline, the hydrogenation activity of the catalyst will be insufficient, and it will be unable to meet the requirements for hydrogenation saturation of petroleum resins. The imbalance in proportion will affect the mechanical stability of the support. When the proportion of macropores is too high, the porosity of the support will be too large, the compressive strength and wear resistance will decrease, and it will be easy to pulverize and clog the reactor under the high pressure and high flow rate conditions of the hydrogenation reactor. When the proportion of micropores is too high, the support structure will be dense, and the pores will be easily blocked by carbon deposits, which will lead to an accelerated catalyst deactivation rate. Moreover, it will be difficult to accurately control the uniformity of the distribution of the Ni-Zn-Mg tricomponents on the support surface.

[0006] Patent CN105214677B discloses a nickel-based catalyst for the hydrogenation of C9 and above hydrocarbons. It uses θ- or γ-alumina as a support and is prepared via a deposition-precipitation method, comprising 20–50 parts of nickel or its oxide, 0.1–5 parts of cerium or its oxide, and 0.5–8 parts of molybdenum or its oxide. This catalyst enhances hydrogenation activity and stability by introducing auxiliary elements, making it suitable for the hydrogenation of heavy hydrocarbons. However, the support pore size of this catalyst is mainly concentrated in the micropore to small mesopore range (<10 nm), and the pore structure has not been optimized for macromolecular diffusion requirements. When applied to DCPD resins with a kinetic diameter ≥1.2 nm, the mass transfer resistance is relatively large, limiting the effective contact of reactants to the active sites and affecting the hydrogenation depth and catalyst utilization efficiency.

[0007] Patent CN103418384B discloses a high-nickel-content nickel-based catalyst using a silica-alumina composite support. It has a specific surface area of ​​150–400 m² / g and an average pore size of 5–15 nm, suitable for the hydrogenation of cracked gasoline and C9+ fractions. While this catalyst enhances activity by increasing the nickel loading, its pore size distribution remains predominantly mesoporous, lacking a continuous macroporous structure, making it difficult to effectively alleviate the retention and accumulation of macromolecular resins within the pores. Furthermore, this technical solution does not introduce electronic additives to regulate the electronic state of nickel, nor does it employ surface modification methods to suppress side reactions. This results in susceptibility to surface coking due to gum and heteroatoms during long-term operation, limiting its stability.

[0008] Numerous studies indicate that the preparation process of hydrogenation catalysts for fused ring resins still faces significant challenges. Developing a low-cost nickel-based catalyst with high activity, high selectivity, excellent stability, and anti-coking ability is of great significance for promoting the industrial production of hydrogenated DCPD resins. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a nickel-based catalyst for deep hydrogenation of DCPD resin and its preparation method. It aims to solve the technical problems of limited mass transfer, high energy barrier for hydrogenation of fused rings and easy coking and deactivation of existing nickel-based catalysts in the process of hydrogenation of DCPD resin by constructing a hierarchical pore support structure, introducing the electronic auxiliary agent yttrium (Y) to regulate the electronic environment of nickel, and combining it with citric acid surface treatment process.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a nickel-based catalyst for deep hydrogenation of DCPD resin, the catalyst comprising a support, an active component and an electronic additive, wherein, based on the total mass of the catalyst, the active component metallic Ni accounts for 40-60 wt%, the support accounts for 35-60 wt%, and the electronic additive accounts for 1-5 wt%.

[0011] The carrier has a hierarchical pore structure, including macropores with a pore size greater than 50 nm and mesopores with a pore size of 2-50 nm, wherein the volume of macropores accounts for 30-50% of the total pore volume and the volume of mesopores accounts for 50-70% of the total pore volume; the Ni is dispersed in a metallic form on the surface of the carrier and the inner wall of the pores, and the electronic additive is yttrium, which exists in the form of yttrium oxide around the nickel particles. Furthermore, the catalyst surface has a chelate structure formed by carboxyl groups and metal hydroxyl groups, which serves as a stable site for anchoring nickel particles.

[0012] In some specific embodiments, the carrier is selected from alumina, silica and / or diatomaceous earth with a specific surface area greater than 300 m² / g.

[0013] In some specific embodiments, the active component metal Ni is selected from one of nickel nitrate, nickel sulfate, or nickel chloride.

[0014] In some specific embodiments, the electronic additive yttrium is selected from yttrium nitrate. The introduction of yttrium can modify the electronic structure of nickel, reduce the dissociation energy barrier of hydrogen molecules on the nickel surface, and improve the intrinsic hydrogenation activity. At the same time, Y2O3 can exert a "grain boundary pinning" effect after high-temperature calcination, maximally inhibiting the growth of nickel grains.

[0015] In some specific embodiments, its specific surface area is between 150 and 300 m² / g, its pore volume is between 0.4 and 0.8 cm³ / g, and it has a bimodal pore size distribution.

[0016] Another aspect of the present invention provides a method for preparing the above-mentioned nickel-based catalyst, comprising the following steps: (1) Mix the carrier and the pore-forming agent at a mass ratio of (8~10):1, dry at 100-130℃ for 6-9h and calcine at 400-600℃ for 2-4h to obtain a carrier with a hierarchical pore structure containing macropores and mesopores. (2) A co-precipitation method is used to co-precipitate a mixed salt solution of nickel salt and yttrium salt with a precipitant solution on the support. After aging, filtration and washing until neutral, a catalyst precursor is obtained. The mass ratio of nickel salt, yttrium salt and hierarchical porous support is (120-150): (6-12): (17-24). (3) The obtained catalyst precursor is impregnated in 0.05~0.3mol / L citric acid aqueous solution with a liquid-solid ratio of (4-6):1, impregnated at 20~50℃ for 2~12h, and then dried at 90-120℃ for 5-7h. (4) The material processed in step (3) is roasted, reduced and surface passivated to obtain the final catalyst.

[0017] In some specific embodiments, the pore-forming agent is one or more of carbon black, starch, or polymer microspheres, preferably, the polymer microspheres include polystyrene microspheres.

[0018] Preferably, in step (1), the mass ratio of the carrier to the pore-forming agent can be 10:1, 9:1, or 8:1. This ratio determines the dispersion density of the pore-forming agent in the carrier, and thus determines the final volume ratio of the macropores. Excessive pore-forming agent content can lead to excessive macropore connectivity and decreased mechanical strength; insufficient content will prevent the formation of continuous macroporous channels. The drying temperature can be 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, or 130℃, preferably 120℃, which is higher than the boiling point of water but much lower than the decomposition temperature of the pore-forming agent. This allows for efficient removal of free water and organic solvents from the carrier slurry, preventing residual liquid phases from remaining in the slurry. During subsequent calcination, intense vaporization impacts the carrier skeleton, causing pore deformation or collapse. The drying time is 6, 7, 8, or 9 hours, preferably 8 hours, to ensure uniform removal of the liquid phase inside the carrier and consistent drying degree inside and out, avoiding pore distribution deviations caused by uneven local shrinkage. The calcination temperature can be 400, 450, 500, 550, or 600℃, preferably 600℃. Mild calcination at 400-600℃ avoids excessive sintering of mesopores, ensuring that the mesoporous structure is not destroyed, thereby maintaining the preset macropore / mesopore ratio.

[0019] In some specific embodiments, the precipitant is one of sodium carbonate, sodium bicarbonate, or ammonium bicarbonate, and the mass fraction of the precipitant solution is 5-10 wt%, preferably 10 wt%. Sufficient precipitant concentration allows for rapid reaction with metal ions to form a complete precipitate, avoiding incomplete precipitation and insufficient loading of active components due to excessively low concentration. If the concentration exceeds 10 wt%, CO3 in the system... 2- or HCO3 - Uneven distribution easily leads to the formation of metal ion agglomerates in high-concentration areas, disrupting the uniformity of the active components. Simultaneously, high-concentration salt solutions increase washing difficulty, and residual salt can easily clog carrier pores. The co-precipitation reaction temperature is 50-70℃. Too low a temperature results in a slow precipitation reaction, easily forming amorphous hydroxide precursors, which, after calcination, easily sinter the grains, reducing active sites. Too high a temperature leads to an excessively fast precipitation rate, exacerbating metal ion agglomeration and accelerating the decomposition rate of the precipitant (especially ammonium bicarbonate), resulting in precipitant waste. Furthermore, the generated bubbles can impact the precursor, disrupting its bonding stability with the carrier. The system pH is controlled between 7.5 and 9.0, a weakly alkaline range suitable for the co-precipitation requirements of Ni and rare earth electronic additives. Rare earth electronic additive ions (such as La...) 3+ Y 3+ Under weakly alkaline conditions, it forms a hydroxide precipitate, which reacts with Ni. 2+Synchronous precipitation achieves uniform mixing at the atomic level, laying the foundation for the subsequent formation of synergistic active sites; in some specific implementations, the aging time is 3~6 hours.

[0020] In some specific embodiments, in step (3), the concentration of the citric acid aqueous solution is 0.05~0.3mol / L, the impregnation temperature is 20~50℃, and the time is 2~12h. Citric acid is a multidentate chelating agent; the carboxyl and hydroxyl groups in its molecule can react with Ni... 2+ and electronic auxiliary ions (such as La) 3+ Y 3+ To form stable chelates, the concentration of citric acid aqueous solution is less than 0.05 mol / L. The number of citric acid molecules is insufficient to completely encapsulate metal ions, making it difficult to improve the dispersibility of active components. At the same time, it cannot effectively penetrate into the mesopores of the carrier, and can only modify surface metal ions, resulting in low dispersion of active sites in the pores. The viscosity of high-concentration citric acid aqueous solution is high, which easily leads to adsorption and retention in the carrier pores. The carbon residue formed after drying and calcination will block mesopores and macropores, destroy the hierarchical pore structure, and affect the mass transfer efficiency of petroleum resin macromolecules. Temperatures near room temperature reduce the thermal motion rate of citric acid molecules, allowing them to slowly penetrate into the macropores and mesopores of the support, uniformly chelating with metal ions within the pores. This prevents the active component from locally accumulating on the support surface. Above 50°C, the chelating ability of citric acid decreases, and some existing metal-citric acid chelates may decompose. Simultaneously, excessively high temperatures cause the aqueous solution to evaporate too quickly, leading to citric acid crystallization on the support surface and clogging the pores. The impregnation time is crucial to ensure sufficient contact between citric acid and metal ions; an optimal impregnation time is 6-12 hours, preferably 8 hours. This allows citric acid molecules to gradually penetrate into the mesopores and micropores of the support, fully chelating with the metal ions within the pores, breaking down aggregated metal ions into monodisperse chelating units, significantly improving the dispersion of the active component. Furthermore, prolonged impregnation allows the chelation reaction to reach dynamic equilibrium, ensuring the stability of catalyst performance between batches.

[0021] In some specific embodiments, the calcination temperature in step (4) is 400~550℃. This calcination temperature can completely decompose the citric acid chelate, carbonate precipitant residue, and adsorbed water in the catalyst precursor. The reduction temperature is 350~500℃. The surface passivation technology is gradual air passivation. The reduced metallic Ni... 0 It has extremely high reactivity and reacts rapidly with O2 in the air, releasing a large amount of heat, causing Ni to... 0 Grain sintering and even catalyst combustion deactivation, graded air passivation is achieved through slow, controlled oxidation in Ni. 0 A thin and dense oxide film forms on the surface, protecting the reducibility of the active sites.

[0022] The present invention has achieved the following beneficial effects: 1. Hierarchical pore structure: The macropores in the support serve as transport channels, facilitating the rapid diffusion of large-molecule DCPD resin; the mesopores provide a huge specific surface area for high-density loading of active components. Moreover, the macropore volume accounts for 30-50% of the total pore volume, and the mesopore volume accounts for 50-70% of the total pore volume. This structure significantly improves mass transfer efficiency, reduces internal coking, and enhances hydrogenation depth and catalyst deactivation resistance.

[0023] 2. Synergistic effect of electronic additive (Y): The introduction of yttrium can modify the electronic structure of nickel, reduce the dissociation energy barrier of hydrogen molecules on the nickel surface, and make the electron distribution on the Ni surface more conducive to the adsorption and activation of H2 molecules. At the same time, it will not cause the product to be difficult to desorb due to excessive adsorption, thus improving the intrinsic hydrogenation activity and allowing more H2 to dissociate into H per unit time. + Furthermore, it reacts rapidly with unsaturated bonds, significantly improving the hydrogenation conversion rate of the catalyst. Simultaneously, Y2O3, after high-temperature calcination, exhibits a "grain boundary pinning" effect, maximally inhibiting the agglomeration and growth of nickel grains.

[0024] 3. Citric acid treatment enhances stability and prevents coking: As an organic chelating agent, citric acid's carboxyl groups can strongly interact with hydroxyl groups on the support surface and metal species such as nickel. This interaction can anchor the active metal and prevent sintering. At the same time, citric acid treatment can moderately modulate the acidity of the support surface, reducing strong acid centers, thereby significantly inhibiting coking and deactivation of DCPD resin during hydrogenation due to side reactions such as cracking and condensation, and extending catalyst life.

[0025] 4. Advantages of precipitation method: The co-precipitation method can achieve highly uniform dispersion and close contact of active component nickel and additives on the support, which is conducive to the formation of synergistic effect and ensures the uniformity and reproducibility of catalyst performance. Detailed Implementation

[0026] The embodiments of the present invention will now be clearly and completely described in conjunction with examples. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, the test methods or detection methods used in the embodiments of this invention are all conventional methods; the materials, reagents, equipment, etc. used are all commercially available unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are from the same batch.

[0028] Example 1 This embodiment provides a nickel-based catalyst S-1 for deep hydrogenation of DCPD resin, comprising an alumina support, an active component Ni, and an auxiliary metal Y; by mass fraction of the catalyst, the active component metal Ni accounts for 60%, the support accounts for 35%, and the auxiliary metal Y accounts for 5%. The nickel-based catalyst has a specific surface area of ​​251.39 m² / g and a pore volume of 0.4466 cm³ / g. The alumina support has a hierarchical pore structure, including macropores with a pore size greater than 50 nm and mesopores with a pore size of 2-50 nm, wherein the macropore volume accounts for 31.24% of the total pore volume and the mesopore volume accounts for 68.76% of the total pore volume; the Ni particles are dispersed on the surface of the support and the inner wall of the pores, the average particle size of the Ni particles is 8.5 nm, and the dispersion is 46.3%-47.1%, wherein yttrium exists in the form of yttrium oxide around the nickel particles. The nickel-based catalyst has a five-membered ring chelate structure and / or a six-membered ring chelate structure formed by carboxyl groups and metal hydroxyl groups on its surface. This chelate structure is a stable site for anchoring nickel particles, and the metal hydroxyl groups are Ni-OH and / or Y-OH.

[0029] The specific preparation method is as follows: Step 1: Mix alumina powder and carbon black powder evenly at a mass ratio of 10:1, extrude into strips, dry at 120℃ for 8 hours, and then calcine at 550℃ for 4 hours to obtain an alumina carrier with hierarchical channels.

[0030] Step 2: Weigh 148.64g Ni(NO3)2·6H2O and 10.77g Y(NO3)3·6H2O, dissolve them to obtain mixed salt solution A, and prepare a 10wt% sodium carbonate solution as precipitation solution B. Take 17.5g of the alumina support obtained in Step 1 and place it in a three-necked flask. Add 100mL of deionized water as the base solution, heat to 60℃ and stir, while simultaneously adding solutions A and B dropwise in parallel, controlling the dropping rate to maintain the pH at around 8.5. After the addition is complete, age at 60℃ for 4 hours. Filter and wash with deionized water until neutral to obtain the catalyst precursor.

[0031] Step 3: The obtained catalyst precursor was impregnated in a 0.1 mol / L citric acid solution (liquid-solid ratio 5:1 mL / g) at 50 °C for 6 h. After treatment, the sample was dried at 100 °C for 6 h.

[0032] Step 4: The dried sample was calcined in a muffle furnace at 450℃ for 4 hours to obtain the catalyst oxide precursor. Before use, the catalyst oxide precursor was reduced at 500℃ for 3 hours in a pure hydrogen atmosphere, and after surface passivation, the final nickel-based catalyst S-1 was obtained.

[0033] Example 2 This embodiment provides a nickel-based catalyst S-2 for deep hydrogenation of DCPD resin. The catalyst includes a silica support, an active component Ni, and an auxiliary metal Y. By mass fraction, the active component Ni accounts for 54%, the support for 42%, and the auxiliary metal Y for 4%. The nickel-based catalyst has a specific surface area of ​​258.62 m² / g and a pore volume between 0.4614 cm³ / g. The silica support has a hierarchical pore structure, containing macropores larger than 50 nm and mesopores with pore sizes of 2-50 nm. The macropore volume accounts for 31.79% of the total pore volume, and the mesopore volume accounts for 68.21%. The Ni particles are dispersed on the surface of the support and the inner walls of the pores, with an average particle size of 8.3 nm and a dispersion of 45.2%-46.0%. Yttrium exists in the form of yttrium oxide around the nickel particles. The nickel-based catalyst has a five-membered ring chelate structure and / or a six-membered ring chelate structure formed by carboxyl groups and metal hydroxyl groups on its surface. This chelate structure is a stable site for anchoring nickel particles, and the metal hydroxyl groups are Ni-OH and / or Y-OH.

[0034] The specific preparation method is as follows: Step 1: Mix silica powder and carbon black powder evenly at a mass ratio of 10:1, extrude into strips, dry at 120℃ for 8 hours, and then calcine at 600℃ for 3 hours to obtain a silica carrier with hierarchical channels.

[0035] Step 2: Weigh 133.78g Ni(NO3)2·6H2O and 8.62g Y(NO3)3·6H2O, dissolve them to obtain mixed salt solution A, and prepare a 10wt% sodium bicarbonate solution as precipitation solution B. Take 21g of the hierarchical silica support obtained in Step 1 and place it in a three-necked flask, add 100mL of deionized water as the base solution, heat to 60℃ and stir. Simultaneously add solutions A and B dropwise, controlling the dropping rate to maintain the pH at around 8.0. After the addition is complete, age at 60℃ for 4 hours. Filter, wash with deionized water until neutral, to obtain the catalyst precursor.

[0036] Step 3: The obtained catalyst precursor was impregnated in a 0.1 mol / L citric acid solution (liquid-solid ratio 5:1 mL / g) at 40 °C for 6 h. After treatment, the sample was dried at 120 °C for 4 h.

[0037] Step 4: The dried sample was calcined in a muffle furnace at 550℃ for 4 hours to obtain the catalyst oxide precursor. Before use, the catalyst oxide precursor was reduced at 500℃ for 3 hours in a pure hydrogen atmosphere, and after surface passivation, the final nickel-based catalyst S-2 was obtained.

[0038] Example 3 This embodiment provides a high-performance nickel-based catalyst S-3, comprising an alumina support, an active component Ni, and an auxiliary metal Y. By mass fraction, the active component Ni accounts for 50%, the support for 47%, and the auxiliary metal Y for 3%. The nickel-based catalyst has a specific surface area of ​​248.13 m² / g and a pore volume of 0.4774 cm³ / g. The alumina support has a hierarchical pore structure, comprising macropores larger than 50 nm and mesopores with pore sizes of 2-50 nm. The macropore volume accounts for 30.83% of the total pore volume, and the mesopore volume accounts for 69.17%. The Ni particles are dispersed on the support surface and the inner walls of the pores, with an average particle size of 9.4 nm and a dispersion of 45.8%-46.4%. Yttrium exists in the form of yttrium oxide around the nickel particles. The nickel-based catalyst has a five-membered ring chelate structure and / or a six-membered ring chelate structure formed by carboxyl groups and metal hydroxyl groups on its surface. This chelate structure is a stable site for anchoring nickel particles, and the metal hydroxyl groups are Ni-OH and / or Y-OH.

[0039] The specific preparation method is as follows: Step 1: Mix alumina powder and starch powder evenly at a mass ratio of 8:1, extrude into strips, dry at 120℃ for 8 hours, and then calcine at 400℃ for 6 hours to obtain an alumina carrier with hierarchical channels.

[0040] Step 2: Weigh 123.87g Ni(NO3)2·6H2O and 6.46g Y(NO3)3·6H2O, dissolve them to obtain mixed salt solution A, and prepare a 10wt% sodium carbonate solution as precipitation solution B. Take 23.5g of the support prepared in Step 1 and place it in a three-necked flask, add 100mL of deionized water as the base solution, heat to 50℃ and stir. Simultaneously add solutions A and B dropwise, controlling the dropping rate to maintain the pH at around 9.0. After the addition is complete, age at 50℃ for 6 hours. Filter, wash with deionized water until neutral, to obtain the catalyst precursor.

[0041] Step 3: Immerse the precursor in a 0.05 mol / L citric acid solution (liquid-to-solid ratio 5:1 mL / g) at 20°C for 12 h. After treatment, dry the sample at 120°C for 4 h.

[0042] Step 4: The dried sample was calcined in a muffle furnace at 400℃ for 6 hours to obtain the catalyst oxide precursor. Before use, the catalyst precursor was reduced at 350℃ for 6 hours in a pure hydrogen atmosphere, and after surface passivation, the final nickel-based catalyst S-3 was obtained.

[0043] Example 4 This embodiment provides a high-performance nickel-based catalyst S-4, comprising a silica support, an active component Ni, and an auxiliary metal Y. By mass fraction, the active component Ni accounts for 46%, the support for 52%, and the auxiliary metal Y for 2%. The nickel-based catalyst has a specific surface area of ​​258.87 m² / g and a pore volume of 0.4345 cm³ / g. The silica support has a hierarchical pore structure, comprising macropores larger than 50 nm and mesopores with pore sizes of 2-50 nm. The macropore volume accounts for 32.41% of the total pore volume, and the mesopore volume accounts for 67.59%. The Ni particles are dispersed on the surface of the support and the inner walls of the pores, with an average particle size of 8.8 nm and a dispersion of 46.0%-46.4%. Yttrium exists in the form of yttrium oxide around the nickel particles. The nickel-based catalyst has a five-membered ring chelate structure and / or a six-membered ring chelate structure formed by carboxyl groups and metal hydroxyl groups on its surface. This chelate structure is a stable site for anchoring nickel particles, and the metal hydroxyl groups are Ni-OH and / or Y-OH.

[0044] The specific preparation method is as follows: Step 1: Mix silica and starch powder evenly at a mass ratio of 8:1, extrude into strips, dry at 120℃ for 8 hours, and then calcine at 450℃ for 6 hours to obtain a silica carrier with hierarchical channels.

[0045] Step 2: Weigh 113.96g Ni(NO3)2·6H2O and 4.31g Y(NO3)3·6H2O, dissolve them to obtain mixed salt solution A, and prepare a 5wt% ammonium bicarbonate solution as precipitation solution B. Take 26g of the support prepared in Step 1 and place it in a three-necked flask, add 100mL of deionized water as the base solution, heat to 70℃ and stir. Simultaneously add solutions A and B dropwise, controlling the dropping rate to maintain the pH at around 7.5. After the addition is complete, age at 70℃ for 3 hours. Filter, wash with deionized water until neutral, to obtain the catalyst precursor.

[0046] Step 3: Immerse the precursor in a 0.3 mol / L citric acid solution (liquid-to-solid ratio 5:1 mL / g) at 50°C for 2 h. After treatment, dry the sample at 120°C for 4 h.

[0047] Step 4: The dried sample was calcined in a muffle furnace at 450℃ for 6 hours to obtain the catalyst oxide precursor. Before use, the catalyst oxide precursor was reduced at 450℃ for 3 hours in a pure hydrogen atmosphere, and after surface passivation, the final nickel-based catalyst S-4 was obtained.

[0048] Example 5 This embodiment provides a high-performance nickel-based catalyst S-5, comprising a silica and alumina support, an active component Ni, and an auxiliary metal Y. By mass fraction, the active component Ni accounts for 40%, the support for 58%, and the auxiliary metal Y for 2%. The nickel-based catalyst has a specific surface area of ​​264.68 m² / g and a pore volume of 0.4268 cm³ / g. The silica and alumina support has a hierarchical pore structure, containing macropores larger than 50 nm and mesopores with pore sizes of 2-50 nm. The macropore volume accounts for 34.42% of the total pore volume, and the mesopore volume accounts for 65.58%. The Ni particles are dispersed on the surface of the support and the inner walls of the pores, with an average particle size of 9.7 nm and a dispersion of 47.5%-48.0%. Yttrium exists in the form of yttrium oxide around the nickel particles. The nickel-based catalyst has a five-membered ring chelate structure and / or a six-membered ring chelate structure formed by carboxyl groups and metal hydroxyl groups on its surface. This chelate structure is a stable site for anchoring nickel particles, and the metal hydroxyl groups are Ni-OH and / or Y-OH.

[0049] The specific preparation method is as follows: Step 1: Mix silica, alumina and polystyrene microspheres evenly at a mass ratio of 5:5:1, extrude into strips, dry at 120℃ for 8 hours, and then calcine at 600℃ for 4 hours to obtain a silica-alumina composite carrier with hierarchical channels.

[0050] Step 2: Weigh 99.1g Ni(NO3)2·6H2O and 4.31g Y(NO3)3·6H2O, dissolve them to obtain mixed salt solution A, and prepare a 10wt% sodium carbonate solution as precipitation solution B. Take 29g of the support obtained in Step 1 and place it in a three-necked flask, add 100mL of deionized water as the base solution, heat to 60℃ and stir. Simultaneously add solutions A and B dropwise, controlling the dropping rate to maintain the pH at around 8.5. After the addition is complete, age at 60℃ for 4 hours. Filter, wash with deionized water until neutral, to obtain the catalyst precursor.

[0051] Step 3: Immerse the precursor in a 0.1 mol / L citric acid solution (liquid-to-solid ratio 5:1 mL / g) at 40℃ for 8 h. After treatment, dry the sample at 100℃ for 6 h.

[0052] Step 4: The dried sample was calcined in a muffle furnace at 550℃ for 4 hours to obtain the catalyst oxide precursor. Before use, the catalyst oxide precursor was reduced at 450℃ for 3 hours in a pure hydrogen atmosphere, and after surface passivation, the final nickel-based catalyst S-5 was obtained.

[0053] Example 6 (without adding Y-adjuvant) This embodiment provides a high-performance nickel-based catalyst S-6, which includes a support and an active component Ni. By mass fraction, the active component metallic Ni accounts for 40%, and the support accounts for 60%. The nickel-based catalyst has a specific surface area of ​​241.74 m² / g and a pore volume of 0.4824 cm³ / g. The silica and alumina support has a hierarchical pore structure, containing macropores with a pore size greater than 50 nm and mesopores with a pore size of 2-50 nm. The macropore volume accounts for 30.10% of the total pore volume, and the mesopore volume accounts for 69.90% of the total pore volume. The Ni particles are dispersed on the surface of the support and the inner walls of the pores, with an average particle size of 10.2 nm and a dispersion of 38.2%-38.5%.

[0054] The specific preparation process is the same as in Example 5, resulting in the final nickel-based catalyst S-6.

[0055] Comparative Example 1 (Conventional Method) A commercially available γ-Al₂O₃ support was used, and a nickel nitrate solution with an equivalent metal content of 40 wt% was loaded onto it using an equal-volume impregnation method. After treatment, the solution was dried at 120 °C for 10 h and calcined at 500 °C for 4 h to obtain catalyst D-1. The nickel-based catalyst has a specific surface area of ​​237.62 m² / g, a pore volume of 0.4602 cm³ / g, with macropores accounting for 14.93% of the total pore volume and mesopores accounting for 85.07% of the total pore volume. The Ni particles are dispersed on the surface of the support and the inner walls of the pores, with an average particle size of 8.0 nm and a dispersion of 31.5%-33.6%.

[0056] Comparative Example 2 (without citric acid treatment) The preparation process is the same as in Example 5, but the citric acid treatment step is omitted. The catalyst precursor washed in step two is directly dried, calcined, and reduced to obtain catalyst D-2. The nickel-based catalyst has a specific surface area of ​​240.80 m² / g and a pore volume of 0.4791 cm³ / g. The silica and alumina supports have a hierarchical pore structure, including macropores with a pore size greater than 50 nm and mesopores with a pore size of 2-50 nm. The macropore volume accounts for 29.95% of the total pore volume, and the mesopore volume accounts for 70.05% of the total pore volume. The Ni particles are dispersed on the surface of the support and the inner wall of the pores. The average particle size of the Ni particles is 8.4 nm, and the dispersion is 43.6%-44.3%.

[0057] Test Example 1 The pore structure, Ni particle size, and dispersion of the catalysts prepared in Examples S-1 to S-6, D-1, and D-2 were investigated. The specific surface area was determined by the BET method, the total pore volume plus the proportion of mesopores was determined by the low-temperature N2 adsorption-desorption method (BJH method), the proportion of macropores was determined by the mercury intrusion porosimetry (MIP method), the Ni particle size was determined by X-ray diffraction (XRD), and the dispersion of nickel particles was determined by H2 chemisorption (reduction conditions: 400℃, H2 atmosphere, 2h; adsorption conditions: 30℃, 0.1MPa). The results are shown in Table 1.

[0058] Table 1 shows the pore structure parameters and Ni particle size parameters for Examples S-1 to S-6, D-1, and D-2.

[0059] Example 1 The catalysts S-1~6 obtained in Examples 1-6 and catalysts D-1~2 obtained in Comparative Examples 1-2 were used to evaluate the hydrogenation performance of DCPD resin. The reaction conditions were: continuous fixed-bed reactor, catalyst loading 10 mL, DCPD resin feed space velocity 0.5 h⁻¹, H₂ pressure 6.0 MPa, and temperature 220 °C. The catalytic performance was evaluated by measuring the bromine value and color (Gardner color standard) of the resin after hydrogenation. The bromine value was measured using an SH0630 automatic bromine value and bromine index analyzer, and the color was measured using a CS-810 benchtop colorimeter. The initial bromine value of the feedstock was 120 g Br₂ / 100 g. The results are shown in Table 2 below. The experimental results above show that the initial bromine value of catalysts S-1 to S-6 in the examples is 1.1 to 1.8 gBr2 / 100g, which is much lower than the initial bromine value of the raw material (120 gBr2 / 100g) and much better than that of the comparative example. Catalyst S-5 in Example 5 has the lowest initial bromine value (1.1 gBr2 / 100g) and the best hydrogenation activity. Furthermore, the surface area of ​​Example 5 is 264.68 m² / g, with macropores accounting for 34.42% of the total pore volume and mesopores accounting for 65.58% of the total pore volume. The ratio of macropore volume to mesopore volume is suitable, and the Ni particle dispersion is 47.5%-48.0%. The high dispersion provides more hydrogenation active sites, thereby improving hydrogenation efficiency and stability, which are the best technical effects in the examples.

[0060] The initial color of catalysts S-1 to S-6 in all examples was <1, which is a significant advantage compared to D-1 (color of 5) in Comparative Example 1, proving that the catalysts in these examples can effectively suppress side reactions and ensure product quality. Although the color of catalyst D-2 in Comparative Example 2 was also <1, its bromine value was higher than that of most examples, indicating that its selectivity was acceptable but its hydrogenation activity was insufficient.

[0061] After 200 hours, the bromine value of catalysts S-1 to S-6 in the examples was 1.4 to 2.7 gBr2 / 100g, which was a small increase compared to the initial bromine value (maximum increase of 1.2 gBr2 / 100g), indicating excellent stability of the active sites. In contrast, the bromine value of D-1 soared to 12.0 gBr2 / 100g after 200 hours, and the activity was almost lost. The bromine value of D-2 rose to 5.5 gBr2 / 100g, and the stability was much worse than that of the examples.

[0062] The catalysts in the examples had a carbon deposition rate of 3.0%~6.2%wt, which was much lower than that of comparative examples D-1 (15.8wt%) and D-2 (9.7wt%). In example 5, S-5 had the lowest carbon deposition rate (3.0wt%), which matched its optimal stability. This was due to the electronic regulation effect of Y promoter and the highly dispersed active sites brought about by citric acid chelation, which could effectively inhibit the adsorption of carbon deposition precursors. In addition, the hierarchical pore structure with a macropore ratio of 30%~50% could effectively reduce the diffusion resistance of reactants / products and reduce carbon deposition. In contrast, the macropore ratio of examples D-1 and D-2 was only 14.93%~29.95%, with high diffusion resistance and fast carbon deposition rate.

[0063] Catalyst S-6 in Example 6, without the addition of additive Y, showed significantly worse initial bromine value, bromine value of the product after 200 hours, and carbon deposition on the catalyst after 200 hours compared to other examples. However, it was superior to Comparative Example 2, indicating that the effect of citric acid treatment was greater than that of additive Y.

[0064] The key role of citric acid treatment was demonstrated through a direct comparison between S-5 and D-2. With the same support and additives, the S-5 catalyst treated with citric acid showed a significant improvement in long-term stability (bromine value only 1.4 after 200 hours) and anti-coking ability (carbon deposition 3.0% vs. 9.7%), indicating a remarkable anti-sintering effect.

[0065] The catalysts S-1 to S-6 in Examples 1-6, due to the synergistic effect of hierarchical pore support construction, electronic additive (Y) modification, and citric acid surface treatment, and the high dispersion of active components achieved by precipitation method, have a huge advantage over the traditional technology Comparative Example 1 (D-1), and are comprehensively superior in terms of reaction activity, selectivity, stability and anti-coking ability.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nickel-based catalyst for deep hydrogenation of DCPD resin, characterized in that, The catalyst comprises a support, an active component, and an electronic additive. Based on the total mass of the catalyst, the active component, metallic Ni, accounts for 40-60 wt%, the support accounts for 35-60 wt%, and the electronic additive accounts for 1-5 wt%. The carrier has a hierarchical pore structure, comprising macropores with a pore size greater than 50 nm and mesopores with a pore size of 2-50 nm, wherein the volume of macropores accounts for 30-50% of the total pore volume and the volume of mesopores accounts for 50-70% of the total pore volume; the Ni particles are dispersed on the surface of the carrier and the inner wall of the pores, the average particle size of the Ni particles is 5-12 nm, the dispersion is ≥30%, and the electronic additive is yttrium, which exists in the form of yttrium oxide around the nickel particles.

2. The nickel-based catalyst according to claim 1, characterized in that, The nickel-based catalyst has a five-membered ring chelate structure and / or a six-membered ring chelate structure formed by a carboxyl group and a metal hydroxyl group on its surface. This chelate structure serves as a stable site for anchoring nickel particles. The metal hydroxyl group is Ni-OH and / or Y-OH.

3. The nickel-based catalyst according to claim 1 or 2, characterized in that, The carrier is selected from alumina, silica and / or diatomaceous earth with a specific surface area greater than 300 m² / g.

4. The nickel-based catalyst according to claim 1 or 2, characterized in that, The active component, metallic Ni, is selected from nickel nitrate, nickel sulfate, or nickel chloride, and / or the electronic additive, yttrium, is selected from yttrium nitrate.

5. The nickel-based catalyst according to claim 1 or 2, characterized in that, The nickel-based catalyst has a specific surface area between 150 and 300 m² / g, a pore volume between 0.4 and 0.8 cm³ / g, and a bimodal pore size distribution.

6. A method for preparing a nickel-based catalyst as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Mix the carrier and the pore-forming agent at a mass ratio of (8~10):1, dry at 100-130℃ for 6-9h and calcine at 550-650℃ for 2-4h to obtain a carrier with a hierarchical pore structure containing macropores and mesopores. (2) A co-precipitation method is adopted to co-precipitate a mixed salt solution of nickel salt and yttrium salt with a precipitant solution on the hierarchical porous structure support. After aging, filtration and washing until neutral, a catalyst precursor is obtained. The mass ratio of nickel salt, yttrium salt and hierarchical porous structure support is (120-150): (6-12): (17-24). (3) The obtained catalyst precursor is impregnated in 0.05~0.3mol / L citric acid aqueous solution with a liquid-solid ratio of (4-6):1, impregnated at 20~50℃ for 2~12h, and then dried at 90-120℃ for 5-7h. (4) The material processed in step (3) is roasted, reduced and surface passivated to obtain the final catalyst.

7. The preparation method according to claim 6, characterized in that, In step (1), the pore-forming agent is one or more of carbon black, starch, or polymer microspheres.

8. The preparation method according to claim 6, characterized in that, In step (2), the precipitant is one of sodium carbonate, sodium bicarbonate or ammonium bicarbonate, the mass fraction of the precipitant solution is 5~10wt%, the reaction temperature of coprecipitation is 50~70℃, the pH value of the system is controlled at 7.5~9.0, and the aging time is 3~6h.

9. The preparation method according to claim 6, characterized in that, In step (3), the concentration of the citric acid aqueous solution is 0.05~0.3mol / L, the immersion temperature is 20~50℃, and the time is 2~12h.

10. The preparation method according to claim 6, characterized in that, The calcination temperature in step (4) is 400~550℃, the reduction temperature is 350~500℃, and the surface passivation technology is gradual air passivation.

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