Preparation method of high-stability supported nickel-based catalyst and application of high-stability supported nickel-based catalyst in unsaturated resin hydrogenation

Abstract

The invention discloses a preparation method and application of a high-stability supported nickel-based catalyst. Firstly, active component metal is supported on silicon dioxide by adopting an ammonia distillation method to prepare a silicate precursor, and then hydro-thermal treatment is performed to form a nanosheet-shaped silicate structure; the synthesis method disclosed by the invention is simple, and the obtained catalyst has active nickel particles with relatively small particle sizes and relatively strong metal-carrier interaction, is stable in performance and is easy for industrial production. The catalyst is used in unsaturated resin hydrogenation reaction, has high catalytic hydrogenation activity, and can be used for preparing high-quality hydrogenated resin.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a highly stable supported nickel-based catalyst and its application in the hydrogenation of unsaturated resins. Background Art

[0002] In the by-products C5 and C9 fractions (about 15 - 25% of the ethylene production) generated during the cracking process of ethylene plants, there are various components with comprehensive utilization value, such as dicyclopentadiene, cyclopentadiene, styrene, etc. How to make full use of C5 and C9 fractions to increase their added value has become an important research direction. Petroleum resins are a class of high-performance thermoplastic elastomers synthesized by thermal polymerization or catalytic polymerization using C5 or C9 fractions as raw materials. Their molecular weight ranges from 300 to 3000, and they have excellent processing properties, mechanical properties, chemical corrosion resistance (especially acid and alkali resistance), and good organic compatibility. At the same time, they are inexpensive and have a simple synthesis process, which is an effective way to make full use of ethylene cracking by-products. They are widely used in many manufacturing fields such as the automotive industry, engineering pipelines, medical devices, coating industry, and printing industry, usually as adhesives and rubber resin additives. However, there are still a large number of unsaturated double bonds and impurities in the molecular structure of resins prepared by conventional polymerization processes, resulting in defects such as deep color, high content of volatile organic compounds (VOCs), insufficient thermal stability, and poor antioxidant performance. These factors severely restrict the expansion of their application scope. Currently, catalytic hydrogenation technology is generally used in the industry to modify petroleum resins by hydrogenating the unsaturated double bonds in the resin molecules and removing impurities. After hydrogenation modification, the unsaturation of the product is significantly reduced, the color of the resin is improved to colorless and transparent, the content of volatile organic compounds is greatly reduced, and at the same time, key performance indicators such as its adhesion performance, thermal stability, and antioxidant performance are significantly improved, thus greatly expanding its application field.

[0003] Petroleum resin hydrogenation catalysts are mainly Pd-based catalysts and Ni-based catalysts. Pd-based catalysts have high catalytic hydrogenation activity for petroleum resins and can effectively reduce the hydrogenation degradation of petroleum resins. Patent CN103386302A discloses a Pd-based petroleum resin hydrogenation catalyst, which uses γ-Al2O3 as a carrier, loads precious metal Pd and oxide additives, and the resulting catalyst contains more than 90% of metal Pd crystallites with a particle size of less than 3 nm. The color number of C9 petroleum resin is reduced from 10# to below 4#, and the softening point is reduced by less than 10 °C. Patent CN111097412A proposes a liquid phase hydrogenation method for poly-DCPD petroleum resin based on a modified palladium-based supported catalyst, which is carried out using a two-stage fixed reactor, one stage using white clay to remove impurities and hydrodesulfurization, and the second stage for hydrofining, wherein Pd and W are used as active components and activated carbon coated with γ-Al2O3 film as a carrier catalyst, and the contents of Pd and W are 0.2-0.37% and 0.45-0.6% respectively. The hydrogenation reaction temperature is 185-240°C, the pressure is 8-11MPa, and the liquid hourly volume rate is 0.8-1.1hr -1 , the obtained hydrogenated resin has a hydrogenation degree of more than 97% and a softening point of 122-124℃. However, the use of precious metal catalysts is costly and difficult to recycle. At the same time, precious metal catalysts are more sensitive to impurities such as residual sulfur compounds in petroleum resins, and are easily combined with them to cause irreversible poisoning and inactivation. The stability is poor, which greatly restricts its large-scale production and application. Ni-based catalysts have good hydrogenation activity and resistance to sulfur poisoning. Their hydrogen absorption capacity is second only to precious metals Pt and Pd, which is conducive to their wide application in large-scale and industrialized catalytic hydrogenation of petroleum resins. Patent CN117563615A reports a catalyst for catalyzing the hydrogenation of DCPD petroleum resin, its preparation method and application, wherein the active component of the catalyst is nickel nanoparticles, accounting for 30-50% of the catalyst mass ratio, diatomaceous earth is the carrier, accounting for 50-80%, and the auxiliary agent molybdenum is 5-20%; the reaction temperature is 220-260 ℃, the hydrogen pressure is 5-7MPa, the reaction is 1-10h, and the obtained resin hydrogenation degree is 97%, and the chromaticity is 3#. However, Ni-based catalysts often use high loading and high temperature and high pressure reaction conditions to improve the performance indicators of hydrogenated petroleum resin, which is easy to cause the active components of the catalyst to agglomerate and reduce the activity. At the same time, higher requirements are put forward for the reaction equipment, resulting in an increase in equipment operation and maintenance costs and energy consumption. Therefore, the development of a petroleum resin hydrogenation catalyst with high hydrogenation activity, high stability, simple preparation and low cost has important industrial practical value and scientific significance for the preparation of high-quality hydrogenated petroleum resin and the optimization of the synthesis route of nickel-based catalysts. Summary of the invention

[0004] To solve the above problems, the present invention provides a preparation method of a highly stable supported nickel-based catalyst and its application in the hydrogenation of unsaturated resins. First, a nickel source and a silicon source are combined by an ammonia evaporation method to form a nickel silicate precursor, and hydrothermal crystallization is further used to promote the formation of a nanosheet morphology and enhance the metal-support interaction. Then, a supported nickel-based catalyst with small particle size, high activity and high stability is prepared by calcination activation and reduction. The catalyst has high catalytic hydrogenation activity for the catalytic hydrogenation of unsaturated resins. Using this catalyst, high-quality hydrogenated resins with high hydrogenation rate and water-white color can be obtained, and at the same time, it has good stability and is suitable for industrial production.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: A highly stable supported nickel-based catalyst, and the preparation method includes the following steps: (1) Dissolve the nickel source precursor (optional metal promoter M precursor) in deionized water, and dropwise add ammonia water with a concentration of 28% to obtain a dark blue clear solution; (2) Disperse the silicon source precursor in deionized water and stir well at room temperature to obtain a silicon source precursor solution; (3) Dropwise add the silicon source precursor solution obtained in step (2) into the clear solution obtained in step (1), stir well at room temperature to obtain a mixed suspension of the nickel source and the silicon source, heat the mixed suspension to 80 °C until the solution pH = 6 - 7, and cool to room temperature. During this process, a complex (Ni(NH3)6 2+ ) is formed by the nickel source in an ammonia environment. At the same time, during the high-temperature stirring process, ammonia gas gradually evaporates, and the surface of the silicon source is dissolved by heating and local over-alkalinity and is initially combined with the complex. In an anchoring + complexing manner, the uniform distribution of the nickel source is promoted and the aggregation of the nickel source is inhibited; (4) Transfer the mixed solution obtained in step (3) to a stainless steel reaction kettle with a polytetrafluoroethylene liner, then place it in an oven, and carry out static hydrothermal crystallization at 90 - 180 °C for 6 - 24 h. Through crystallization, the combination of the silicon source and the nickel source is further increased, and the dispersion of the nickel source is improved. Cool to room temperature, filter, wash with deionized water and ethanol, and place the precursor precipitate in an oven or a vacuum oven and dry it at 80 °C to constant weight to obtain catalyst precursor X; (5) Place the precursor X obtained in step (4) in a muffle furnace, calcine and activate it at 400 - 800 °C in an air atmosphere for 2 - 4 h, and control the calcination heating rate at 2 - 5 °C to gradually precipitate nickel particles in nickel silicate. By controlling the heating rate, the growth size of nickel particles is controlled, and at the same time, a part of unreduced nickel silicate is retained to regulate the acidity and alkalinity of the catalyst and improve the adsorption and activation ability of unsaturated double bonds. Then, place it in a reducing atmosphere for reduction to obtain the nickel-based catalyst for the hydrogenation of unsaturated resins.

[0006] Furthermore, the nickel source precursor used in step (1) is any one of nickel nitrate, nickel chloride, nickel sulfate, nickel acetate or nickel acetylacetonate; the metal additive M is one or a mixture of Cu and Mo, and its precursor is any one of nitrate, sulfate, chloride, acetylacetonate and ammonium salt; the molar ratio of metal to ammonia water is n(Ni) / n(ammonia water) or (n(Ni)+n(M)) / n(ammonia water)=1:6-1:9.

[0007] Furthermore, the silicon source precursor used in step (2) is any one of alkaline silica sol, neutral silica sol, and fumed silica.

[0008] Furthermore, the reducing atmosphere in step (5) is a mixture of hydrogen and an inert gas, wherein the volume concentration of hydrogen is 10%, and the inert gas is either chlorine or nitrogen; the reduction temperature is 500-800 ° C, the time is 2-4 h, and the reducing gas flow rate is maintained at 50-100 mL / min.

[0009] The supported nickel-based catalyst can be used for catalytic hydrogenation reaction of unsaturated resin.

[0010] Its specific application method: taking DCPD petroleum resin as an example, dissolve DCPD petroleum resin in an organic solvent to prepare a resin solution of a certain concentration, load the supported nickel-based catalyst and the resin solution into a reactor, replace the air with nitrogen and hydrogen respectively after sealing, then fill with hydrogen at a certain pressure, and slowly heat to the reaction temperature. After the reaction is completed, the product is filtered, extracted with anhydrous ethanol, and dried to obtain block hydrogenated DCPD petroleum resin.

[0011] The mass ratio of resin to solvent is 1:10, and the selected organic solvent is one or a mixture of two or more of cyclohexane, methylcyclohexane, n-heptane, tetrahydrofuran, and decahydronaphthalene; the amount of catalyst is 1 wt% of the resin solution, the reaction temperature is 160-200 °C, the reaction pressure is 3-5 MPa, and the reaction time is 3-6 h.

[0012] The beneficial effects of the present invention are: (1) The supported nickel-based catalyst prepared by the present invention has the characteristics of small active component particle size and high dispersion, high hydrogenation activity, and the use of nickel silicate as a precursor improves the stability of the catalyst. In addition, the preparation method is simple, the cost is low, and it is easy to scale up production.

[0013] (2) The addition of metal additive M can form a Ni-M alloy with the active component nickel nanoparticles, further improving the low-temperature hydrogenation activity of unsaturated resin. The hydrogenation degree of the hydrogenated resin prepared at a reaction temperature of 160-200 °C is higher than 99%, and the Gardner color is less than 1#. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 XRD patterns of the catalyst precursors for Example 1 and Comparative Examples 1-2.

[0015] Figure 2 XRD patterns of the catalysts for Example 1 and Comparative Examples 1-2.

[0016] Figure 3 H2-TPR profiles of the catalysts for Example 1 and Comparative Examples 1-2.

[0017] Figure 4 NH3-TPD profiles of the catalysts for Example 1 and Comparative Examples 1-2.

[0018] Figure 5 SEM image of the catalyst for Example 1.

[0019] Figure 6 XRD patterns of the catalysts for Examples 2-3 and Comparative Example 3. Detailed implementation manners

[0020] The present invention will be elaborated in detail through the following specific implementation manners, but the implementation manners do not constitute a limitation to the present invention.

[0021] Example 1 (1) Weigh 3 portions of nickel nitrate hexahydrate and dissolve them in 150 portions of deionized water. Stir until completely dissolved, and gradually add 28% ammonia water according to n(Ni) / n(ammonia water) = 1:9 to obtain a dark blue clear solution A. (2) Weigh 8 portions of basic silica sol (Maclean) and disperse it in 50 portions of deionized water. Stir well at room temperature to obtain a dispersion B. (3) Gradually add dispersion B to solution A and stir well at room temperature to obtain a mixed solution C containing nickel source and silicon source. (4) Heat the mixed solution C to 80 °C until the solution pH = 6-7, and then cool it to room temperature. (5) Transfer the cooled mixed solution C to a stainless-steel autoclave with a polytetrafluoroethylene liner, then place it in an oven and perform static hydrothermal crystallization at 180 °C for 24 h. After cooling to room temperature, filter, wash with deionized water and ethanol, and place the precursor precipitate in an oven or vacuum oven to dry at 80 °C to constant weight to obtain catalyst precursor X. (6) Grind the dried catalyst precursor X into powder, place it in a muffle furnace, calcine and activate it in air atmosphere at 700 °C for 4 h, then place it in a 10% H2 / Ar reducing atmosphere and reduce it at 600 °C for 2 h with a heating rate of 2 °C / min and a gas flow rate of 50 mL / min to obtain the nickel-based catalyst for DCPD petroleum resin hydrogenation, denoted as catalyst 1.

[0022] Example 2 In addition to adding 0.2 parts of copper nitrate trihydrate in step (1) and n(Ni+Cu) / n(ammonia water)=1:9, other steps are the same as those in Example 1. The prepared nickel-based catalyst is denoted as Catalyst 2.

[0023] Example 3 In addition to adding 0.2 parts of ammonium molybdate tetrahydrate in step (1) and n(Ni+Mo) / n(ammonia water)=1:9, other steps are the same as those in Example 1. The prepared nickel-based catalyst is denoted as Catalyst 3.

[0024] Example 4 The amounts of copper nitrate trihydrate added in step (1) are 0.1 part, 0.5 part, and 0.8 part respectively, and n(Ni+Cu) / n(ammonia water)=1:9. Other steps are the same as those in Example 1. The prepared nickel-based catalysts are denoted as Catalyst 4, Catalyst 5, and Catalyst 6 respectively.

[0025] Comparative Example 1 (only ammonia evaporation method) (1) Weigh 3 parts of nickel nitrate hexahydrate and dissolve it in 150 parts of deionized water. Stir until completely dissolved. According to n(Ni) / n(ammonia water)=1:9, gradually add 28% ammonia water dropwise to obtain a dark blue clear solution A; (2) Weigh 8 parts of silica sol and disperse it in 50 parts of deionized water. Stir well at room temperature to obtain a dispersion B; (3) Gradually add dispersion B dropwise to solution A and stir well at room temperature to obtain a mixed solution C of nickel source and silicon source; (4) Heat the mixed solution C to 80 °C until the solution pH=6~7, and then cool it to room temperature; (5) Filter, wash, and dry the cooled mixed solution C. Place the obtained solid powder in a muffle furnace and calcine and activate it at 700 °C in an air atmosphere for 4 h, and then reduce it at 600 °C in a 10% H2 / Ar reducing atmosphere for 2 h with a heating rate of 2 °C / min. The prepared nickel-based catalyst is denoted as Catalyst 7.

[0026] Comparative Example 2 (impregnation method) (1) Weigh 3 parts of nickel nitrate hexahydrate and dissolve it in 150 parts of deionized water. Stir until completely dissolved. According to n(Ni) / n(ammonia water)=1:9, gradually add 28% ammonia water dropwise to obtain a dark blue clear solution A; (2) Weigh 8 parts of silica sol and disperse it in 50 parts of deionized water. Stir well at room temperature to obtain a dispersion B; (3) Gradually add dispersion B dropwise to solution A and stir well at room temperature to obtain a mixed solution C of nickel source and silicon source; (4) Heat the mixed solution C obtained in step (3) to 80 °C until the solution is completely evaporated to dryness. Place the obtained solid powder in a muffle furnace and calcine and activate it at 700 °C in an air atmosphere for 4 h, then place it in a 10% H2 / Ar reducing atmosphere and reduce it at 600 °C for 2 h with a heating rate of 2 °C / min. The prepared nickel-based catalyst is denoted as catalyst 8. Comparative Example 3 (different promoters) Replace the metal promoter M with cobalt nitrate hexahydrate and zinc nitrate hexahydrate respectively, and the other steps are the same as in Example 2. The prepared nickel-based catalysts are denoted as catalyst 9 and catalyst 10 respectively.

[0027] The reaction is carried out in a batch autoclave reactor. The reaction temperature is 180 °C, the hydrogen pressure is 4.0 MPa, the reaction substrate is a 10 wt% DCPD petroleum resin solution, and the solvent is cyclohexane. The chromaticity is measured by a Gardner colorimeter, and the results are shown in Table 1.

[0028] Table 1 Hydrogenation performance of various catalysts on DCPD petroleum resin

[0029] It can be seen from Figure 1 that the catalyst precursor prepared by the ammonia evaporation method can form a nickel silicate structure, while the ordinary impregnation method can only form an unstable nickel oxide. After the catalyst precursor is reduced ( Figure 2 ), the active component Ni nanoparticles are in-situ generated from the nickel silicate structure. The stability of nickel silicate hinders the agglomeration of Ni particles. From Figure 3 it can be seen that the hydrothermal treatment further enhances the thermal stability of the nickel silicate structure. According to the Scherrer formula, the Ni 0 particle sizes of Example 1 and Comparative Example 1 are 7.2 nm and 9.7 nm respectively. Combining Figure 3 indicates that the hydrothermal treatment further enhances the confinement effect of nickel silicate on nickel particles, and the active component has a high dispersion. From the SEM image of Example 1 ( Figure 5 ) it is further proved that the nickel silicate prepared by the ammonia evaporation-hydrothermal method has a layered structure of stacked nanosheets. It can be seen from Figure 4 that the hydrothermal treatment can expose more acidic sites on the catalyst surface, which is beneficial to the adsorption and activation of the substrate resin molecules. It can be seen from Figure 6 that after doping with metal promoters, the active component Ni and the metal promoter form a Ni-M alloy. After doping with Co and Zn promoters, the nickel nanoparticle sizes increase to 9.2 nm and 10.5 nm respectively, while the particle size changes little when doping with Cu and Mo.

[0030] As can be seen from Table 1, compared with the conventional steam ammonia distillation method and impregnation method, the nickel-based catalyst prepared by the steam ammonia distillation-hydrothermal method proposed in the present invention has better hydrogenation performance. For different doped metal promoters, when adding metal promoters Cu and Mo, the catalyst exhibits more excellent hydrogenation activity under milder conditions, which can be attributed to the stronger metal-support interaction and the synergistic effect of Ni-M. And within a certain range, the increase of Cu doping amount helps to improve the hydrogenation performance of the catalyst.

[0031] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A preparation method of a highly stable supported nickel-based catalyst, characterized in that: Specifically, it includes the following steps: (1) Dissolve the nickel source precursor in deionized water, and dropwise add ammonia water with a concentration of 28% to obtain a clear solution; (2) Disperse the silicon source precursor in deionized water, and fully stir at room temperature to obtain a silicon source precursor solution; (3) Dropwise add the silicon source precursor solution obtained in step (2) into the clear solution obtained in step (1), fully stir at room temperature to obtain a mixed suspension containing the nickel source and the silicon source, heat the mixed suspension to 80 °C until the solution pH = 6 - 7, and cool to room temperature; (4) Transfer the solution obtained in step (3) to a stainless steel autoclave with a polytetrafluoroethylene liner, place it in an oven at 90 - 180 °C for crystallization for 6 - 24 h, then cool to room temperature, and obtain a catalyst precursor after filtration, washing and drying; (5) Place the precursor obtained in step (4) in a muffle furnace, calcine and activate it in an air atmosphere at 400 - 800 °C for 2 - 4 h, and then reduce it in a reducing atmosphere to obtain the high-stability supported nickel-based catalyst.

2. The preparation method according to claim 1, wherein: The clear solution in step (1) further includes a metal promoter M precursor.

3. The preparation method according to claim 1, wherein: The nickel source precursor in step (1) is any one of nickel nitrate, nickel chloride, nickel sulfate, nickel acetate or nickel acetylacetonate.

4. The preparation method according to claim 2, characterized in that: The metal promoter M is one or a mixture of two of Cu and Mo, and its precursor is any one of nitrate, sulfate, chloride, acetylacetonate, ammonium salt; the molar ratio of the metal to ammonia water is 1:6 - 1:9, and the metal is the sum of Ni and the promoter metal M.

5. The preparation method according to claim 1, characterized in that: The silicon source precursor in step (2) is any one of basic silica sol, neutral silica sol, and fumed silica.

6. The preparation method according to claim 1, characterized in that: The reducing atmosphere in step (5) is a mixture of hydrogen and an inert gas, where the volume concentration of hydrogen is 10%, and the inert gas is any one of argon or nitrogen; the reduction temperature is 500 - 800 °C, the time is 2 - 4 h, and the flow rate of the reducing gas is maintained at 50 - 100 mL / min.

7. A supported nickel-based catalyst prepared by the preparation method according to any one of claims 1-6, characterized in that: Based on the total mass of the catalyst being 100%, the content of the active component nickel is 10 - 30 wt%, and the content of the metal promoter M is 2 - 10 wt%.

8. Application of the supported nickel-based catalyst as described in claim 7 in the catalytic hydrogenation of unsaturated resins.

9. The application according to claim 8, wherein: The reaction temperature of the application is 120 - 280 °C, the reaction pressure is 3 - 5 MPa, and the reaction time is 2 - 12 h.

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