Method for preparing high-purity nickel acetate from crude nickel carbonate

Abstract

The invention discloses a method for preparing high-purity nickel acetate from crude nickel carbonate in the technical field of nickel compound purification, which comprises the following steps: mixing the crude nickel carbonate with deionized water to obtain a suspension, and adding glacial acetic acid to react to obtain a nickel acetate solution; then a specially-made hierarchical-pore titanium silicalite molecular sieve loaded bimetallic nanocluster material is added for purification treatment, the material is obtained through precise preparation, the method comprises the steps of carrier modification, bimetallic loading, hydrophobic modification, activation balance and the like, and the material has excellent impurity adsorption capacity and chemical stability; carrying out concentration crystallization and solid-liquid separation on the purified solution to obtain wet nickel acetate crystals; the mother liquor is subjected to adsorption treatment again, crystals in the mother liquor are recycled, and finally all the crystals are combined and dried to obtain a high-purity nickel acetate product. The process is simple and efficient, the purity of the prepared nickel acetate exceeds 98.5%, the content of each impurity is superior to the industrial standard, and the mother liquor can be recycled, is environment-friendly and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of nickel compound purification technology, specifically to a method for preparing high-purity nickel acetate from crude nickel carbonate. Background Technology

[0002] Nickel acetate, as an important chemical raw material and fine chemical, has wide applications in electroplating, catalyst preparation, battery materials, and ceramic colorants. With the rapid development of high-end manufacturing industries such as new energy and electronic components, the market demand for high-purity nickel acetate is increasing, especially with extremely stringent requirements regarding the content of impurities such as iron, copper, zinc, and cobalt. Currently, the main industrial processes for producing nickel acetate include the direct reaction of metallic nickel with acetic acid, the metathesis of nickel salts with sodium acetate, and the neutralization of nickel carbonate with acetic acid. Among these, the reaction of crude nickel carbonate with acetic acid has certain advantages due to its lower raw material cost and milder reaction conditions. However, crude nickel carbonate typically originates from intermediate products of hydrometallurgical processes in mines, resource recovery from electroplating sludge, or byproducts in battery material production. Its chemical composition is complex, generally containing various associated metallic impurities and potentially organic additives. These impurities simultaneously enter the solution during acidolysis, posing significant challenges to subsequent purification and refining, severely limiting the purity and application value of the final product.

[0003] In existing technologies, conventional methods for purifying high-purity nickel acetate solutions containing various impurities mainly include solvent extraction, ion exchange, selective precipitation, and activated carbon adsorption. While these methods have some application, they all have significant limitations. Solvent extraction typically requires multi-stage countercurrent extraction and back-extraction, resulting in a long process flow and the use of large amounts of volatile organic solvents, posing safety and environmental risks. Ion exchange requires high selectivity, exchange capacity, and regeneration performance of the resin, and the resin is easily contaminated and rendered ineffective by organic matter in the solution. Selective precipitation often requires the addition of multiple chemical precipitants, which may introduce new impurities and lead to the co-precipitation loss of target nickel ions, reducing product yield. Ordinary activated carbon adsorption is mainly effective against organic impurities, but its removal effect on transition metal impurity ions with properties similar to nickel is limited. More importantly, these traditional methods struggle to achieve efficient and deep removal of both inorganic heavy metal impurities and organic impurities simultaneously, often requiring a combination of multiple processes, leading to complex operating procedures, increased production costs, and difficulty in consistently obtaining nickel acetate products with a purity higher than 98.5%.

[0004] Therefore, developing a new high-purity nickel acetate preparation technology that can efficiently and deeply remove various impurities from crude nickel carbonate, with a simple process flow, economical cost, and environmental friendliness, has become a key problem urgently needing to be solved in this field. An ideal solution requires a novel functional material capable of simultaneously adsorbing multiple impurities. This material should possess excellent chemical stability, high adsorption selectivity, and good recyclability, thereby simplifying the process while ensuring a significant improvement in product purity, meeting the stringent quality standards of nickel acetate in high-end applications. This invention is proposed against this technological background. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high-purity nickel acetate from crude nickel carbonate, which solves the existing technical problems.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] A method for preparing high-purity nickel acetate from crude nickel carbonate includes the following steps:

[0008] S1, crude nickel carbonate and deionized water are added to a reaction vessel and stirred to obtain a suspension; glacial acetic acid is added to the suspension; the reaction is continued with stirring to obtain a nickel acetate solution;

[0009] S2, add hierarchical porous titanium-silicon molecular sieve-supported bimetallic nanoclusters to nickel acetate solution and stir at 44-46℃; then let stand, filter, and obtain nickel acetate purified solution; collect the hierarchical porous titanium-silicon molecular sieve-supported bimetallic nanoclusters, which can be recycled after regeneration treatment;

[0010] S3, the purified nickel acetate solution is transferred to an evaporator and concentrated at 65-75℃ to obtain a supersaturated nickel acetate solution; the supersaturated nickel acetate solution is transferred to a crystallization vessel and cooled to 14-16℃; after maintaining the temperature for crystal growth, solid-liquid separation is performed by centrifugation to obtain wet nickel acetate crystals and mother liquor from centrifugation.

[0011] S4. Add multi-level porous titanium-silicon molecular sieve-supported bimetallic nanoclusters to the mother liquor after centrifugation, stir, filter, and obtain wet nickel acetate crystals; combine the wet nickel acetate crystals obtained in steps S3 and S4, place them in a vacuum drying oven, and dry at 48-52℃.

[0012] In this invention, the reaction mechanism of the entire process for preparing high-purity nickel acetate from crude nickel carbonate is based on a precise foundation of multi-component synergistic purification and phase equilibrium control. The initial acid leaching reaction is a typical gas-liquid-solid three-phase reaction system. Glacial acetic acid molecules first diffuse to the surface of nickel carbonate particles, undergo a neutralization reaction to generate nickel acetate and release carbon dioxide gas. This process is accompanied by significant solid-phase dissolution and bubble generation. The reaction rate is comprehensively affected by the acetic acid concentration, temperature, and stirring intensity. Appropriate process control can ensure complete dissolution of nickel carbonate while minimizing the loss of volatile acetic acid. Subsequently, the core purification stage begins, where a specially designed multi-level porous material exhibits excellent impurity removal capabilities. Its mechanism involves the synergistic effect of physical adsorption, chemical coordination, and electrostatic attraction. The carefully designed multi-level porous system inside the material acts like a molecular sieve, achieving preliminary sieving and separation based on the size differences of impurity molecules. Larger organic impurity molecules are confined to mesoporous and macroporous regions, while smaller metal ions can enter the microporous channels. More precisely, the key role played by copper-palladium bimetallic nanoclusters is crucial. Palladium species, with their unique d-electron orbital characteristics, exhibit a strong coordination tendency towards transition metal ions such as iron, cobalt, and zinc, forming stable surface complexes. Meanwhile, copper species efficiently capture organic impurity molecules in the solution through π-π stacking interactions and polar interactions. This dual-functional synergy allows the material to simultaneously and deeply remove both inorganic and organic impurities with vastly different properties. Simultaneously, the hydrophobic modification layer on the material surface not only protects the internal metal active sites from acidic corrosion but also enhances the capture ability of nonpolar organic molecules through hydrophobic interactions. During the concentration and crystallization stage, as water molecules evaporate, the nickel acetate solution gradually reaches a supersaturated state. This process requires precise control of temperature and vacuum to avoid excessive local supersaturation that could lead to the instantaneous formation of numerous crystal nuclei. The application of a programmed cooling strategy allows the system to smoothly enter the supersaturated state along the metastable region boundary. At this point, nickel acetate molecules in the solution begin to aggregate in an orderly manner to form crystal nuclei, and under the drive of appropriate supersaturation, gradually grow into complete crystals. The crystal growth process provides opportunities for the tiny crystal nuclei to redissolve and recrystallize, achieving crystal size homogenization and defect repair through the Ostwald ripening mechanism. The final mother liquor treatment embodies the design philosophy of maximizing resource utilization throughout the entire process. Residual nickel ions in the mother liquor are deeply captured by supplementary purification materials and recovered in crystal form, while enriched impurities are concentrated and fixed by adsorption materials, achieving the dual goals of targeted impurity enrichment and efficient recovery of valuable components. Throughout the entire process, each step is interconnected; the preceding step creates optimal conditions for the subsequent stage, and the subsequent step supplements and optimizes the effects of the preceding stage, forming a complete, efficient, and environmentally friendly high-purity nickel acetate preparation system.

[0013] According to a preferred embodiment of the present invention, in step S1, the stirring reaction is continued for 2-4 hours.

[0014] According to a preferred embodiment of the present invention, in step S2, the stirring time is 3-5 hours at 44-46°C.

[0015] According to a preferred embodiment of the present invention, in step S3, the time for heat preservation and crystal growth is 1-2 hours.

[0016] According to a preferred embodiment of the present invention, in step S4, the drying time at 48-52°C is 4-6 hours.

[0017] According to a preferred embodiment of the present invention, the preparation steps of the hierarchical porous titanium-silicon molecular sieve-supported bimetallic nanoclusters material include:

[0018] A1. The titanium-silicon molecular sieve was placed in a muffle furnace and calcined at 545-555℃ in air atmosphere to obtain the calcined sample. The calcined sample was cooled to room temperature, and an aqueous solution of hexadecyltrimethylammonium bromide was added. The mixture was stirred in a water bath at 78-82℃. After filtration, a solid product was obtained. The solid product was washed with deionized water until neutral, immersed in an ethanol solution of polyethylene oxide-polypropylene oxide block copolymer, and sonicated. After filtration again, the mixture was dried in a vacuum drying oven at 38-42℃ to obtain a multi-level porous titanium-silicon molecular sieve support precursor.

[0019] A2, palladium chloride and copper nitrate were dissolved in deionized water to obtain a metal salt solution; a hierarchical porous titanium silicate molecular sieve support precursor was added to the metal salt solution and stirred at 34-36℃; then sodium borohydride aqueous solution was added, and a reduction reaction was carried out under nitrogen protection to obtain a reaction mixture; the reaction mixture was filtered and washed with nitrogen-saturated deionized water to obtain a material loaded with bimetallic nanoclusters.

[0020] A3. The material loaded with bimetallic nanoclusters was immersed in a toluene solution of octadecyltrichlorosilane and treated under reflux conditions; after filtration, it was washed alternately with toluene and ethanol to obtain the washed material loaded with bimetallic nanoclusters; the washed material loaded with bimetallic nanoclusters was redispersed in an ammonia-ammonium chloride buffer solution with pH=8.4-8.6 and aged in a water bath at 78-82℃ to obtain a mixture; after filtering the mixture, it was dried in a vacuum drying oven at 58-62℃ to obtain a multi-level porous titanium-silicon molecular sieve loaded with bimetallic nanoclusters with hydrophobic surface modification;

[0021] A4 involves treating bimetallic nanoclusters supported on a multi-level porous titanium-silicon molecular sieve with hydrophobic surface modification by heating to 295-305℃ in a hydrogen-nitrogen mixture, cooling to room temperature, and equilibrating in an environment with a relative humidity of 40-50%.

[0022] In this invention, the preparation reaction mechanism of bimetallic nanoclusters supported on hierarchical porous titanium-silicon molecular sieves profoundly reflects the design concept and precise construction process of advanced nanostructure materials. The preparation process begins with the structural modification of the titanium-silicon molecular sieve support. High-temperature calcination effectively removes the internal template agent, while some titanium species migrate to the outside of the framework to form secondary channels. This process not only widens the original microporous channels but also creates a rich mesoporous structure, providing a crucial spatial basis for the subsequent adsorption of macromolecular impurities. Subsequently, utilizing the self-assembly properties of hexadecyltrimethylammonium bromide in the aqueous phase, its hydrophilic ends interact with the silanol groups on the molecular sieve surface, causing hydrophobic long chains to extend outwards to form micellar templates. By precisely controlling the temperature and time, an ordered mesoscopic structure is guided to form on the surface and within the channels of the molecular sieve. The introduction of the polyethylene oxide-propylene oxide block copolymer further stabilized this hierarchical porous system. The polyethylene oxide segments are anchored to the molecular sieve surface via hydrogen bonding, while the propylene oxide segments interact with the previously formed micelles through hydrophobic interactions, constructing a stable three-dimensional network structure. This complex porous architecture is ultimately fixed through a drying process. During the bimetallic loading stage, palladium chloride and copper nitrate underwent a complex coordination and ion exchange process within the molecular sieve channels. Palladium ions, with their strong coordination ability, preferentially bind to the titanium oxide sites in the molecular sieve framework, while copper ions are distributed on the inner walls of the channels through interactions with surface silanol groups. The two form a precursor complex within the confined space of the molecular sieve. The slow reduction of sodium borohydride is a key step. Under nitrogen protection, it prevents metal oxidation and gradually reduces palladium and copper ions to zero valence. Due to the spatial confinement of the molecular sieve channels and the difference in reduction potential between the two metal ions, copper atoms precipitate first to form crystal nuclei, followed by palladium atoms depositing on their surface. This ultimately forms a heterogeneous nanocluster structure with copper as the core and palladium as the shell. This unique structure greatly enhances the surface activity and electron transport capacity of the material. Surface hydrophobic modification is achieved through the condensation reaction of octadecyltrichlorosilane with residual silanol groups on the molecular sieve surface. The long-chain alkyl group forms a dense monolayer on the material surface, which not only protects the internal metal nanoclusters from water and oxygen corrosion but also enhances the material's adsorption selectivity for organic impurities by regulating surface hydrophilicity and hydrophobicity. The final activation treatment is carried out under specific humidity conditions. The hydrogen-nitrogen mixture not only further cleans the surface of the metal nanoclusters, creating more active sites, but also ensures the material reaches an ideal hygroscopic equilibrium state by controlling the ambient humidity, guaranteeing stable pore structure and adsorption performance during subsequent use.

[0023] According to a preferred embodiment of the present invention, in step A1, the stirring time in a water bath at 78-82°C is 24-30 hours.

[0024] According to a preferred embodiment of the present invention, in step A2, the molar ratio of palladium chloride to copper nitrate is (1.5-1.7):1; and the stirring time at 34-36°C is 12-14h.

[0025] According to a preferred embodiment of the present invention, in step A3, the processing time under reflux conditions is 6-8 hours.

[0026] According to a preferred embodiment of the present invention, in step A4, the time for heating to 295-305°C is 2-4 hours.

[0027] The beneficial effects of this invention are as follows:

[0028] The technical solution provided by this invention, through innovative material design and process optimization, demonstrates significant technical effects and comprehensive advantages in the preparation of high-purity nickel acetate from crude nickel carbonate. Firstly, it achieves breakthrough progress in purification efficiency and product quality. Traditional methods struggle to simultaneously and efficiently remove multiple impurities with varying properties, particularly transition metal ions such as cobalt and zinc, which have properties similar to nickel ions, as well as potential organic impurities. However, the multi-level porous titanium-silicon molecular sieve-supported bimetallic nanoclusters used in this invention, through their carefully designed composite structure and surface characteristics, achieve simultaneous and efficient adsorption and removal of various impurities. The unique multi-level porous structure of the material provides ample diffusion paths and adsorption sites for impurity molecules of different sizes, while the copper-palladium bimetallic nanoclusters exhibit excellent selective adsorption capabilities for organic and metallic impurities, respectively. This synergistic effect significantly improves the purity of the final product, with the nickel acetate content consistently exceeding 98.5%, and the contents of key impurity elements such as iron, copper, zinc, and cobalt all exceeding the limits of current industry standards, meeting the stringent purity requirements of high-value-added applications such as electronic and catalyst grades.

[0029] Secondly, this technology has significant advantages in terms of process simplification and production cost control. The traditional multi-step purification process is integrated into a single, highly efficient adsorption and purification step, greatly simplifying the operation and reducing equipment investment and energy consumption. Although the preparation process of the hierarchical porous titanium-silicon molecular sieve-supported bimetallic nanoclusters is relatively complex, its excellent adsorption performance and lifespan significantly reduce the cost per treatment. Furthermore, the material can be recycled multiple times after regeneration, further reducing material consumption and waste generation. In addition to the specially prepared hierarchical porous titanium-silicon molecular sieve-supported bimetallic nanoclusters, the glacial acetic acid and deionized water used in the entire process are common commercially available chemical raw materials, requiring no special equipment or expensive reagents, which is conducive to the implementation and promotion of large-scale industrial production. Simultaneously, by optimizing the concentration and crystallization conditions and adopting programmed cooling and crystal growth processes, the crystal morphology and particle size distribution are effectively controlled, improving product yield and quality stability, and avoiding problems such as agglomeration and impurity inclusion common in traditional methods.

[0030] Finally, this technical solution demonstrates excellent performance in resource utilization and environmental protection. By recovering valuable components from the mother liquor and centrally treating impurities, it achieves cleaner production processes and maximizes resource utilization. Residual nickel ions in the mother liquor undergo further treatment using supplemental adsorption materials and are returned to the main process, not only improving the overall nickel recovery rate but also reducing nickel-containing wastewater discharge. The adsorption-saturated multi-level porous titanium-silicon molecular sieve-supported bimetallic nanoclusters can be centrally regenerated, recovering the enriched metallic impurities and achieving resource recycling. The entire process generates no toxic or harmful gases and has extremely low wastewater discharge, aligning with the development concept of green chemistry. Compared to traditional methods, this technology not only significantly improves product quality but also offers outstanding advantages in production costs, ease of operation, and environmental friendliness. It provides a novel technical path for the high-value utilization of crude nickel carbonate, possessing significant industrial application value and promising prospects for widespread application. Detailed Implementation

[0031] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0032] The following is information on domestic suppliers of the relevant equipment and materials:

[0033] The crude nickel carbonate was purchased from Jinchuan Group Co., Ltd.

[0034] The glacial acetic acid was purchased from Jiangsu Suopu Group Co., Ltd.

[0035] The titanium-silicon molecular sieve was purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0036] The hexadecyltrimethylammonium bromide was purchased from Guangzhou Weber Chemical Co., Ltd.

[0037] The polyethylene oxide-polypropylene oxide block copolymer was purchased from Angxing New Carbon Materials Changzhou Co., Ltd.

[0038] The palladium chloride was purchased from Guizhou Platinum Industry Co., Ltd.

[0039] The copper nitrate was purchased from Beijing Chemical Plant Co., Ltd.

[0040] The sodium borohydride was purchased from Tianjin Bodi Chemical Co., Ltd.

[0041] The octadecyltrichlorosilane was purchased from Hangzhou Jessica Chemical Co., Ltd.

[0042] Example 1

[0043] This embodiment provides a method for preparing high-purity nickel acetate from crude nickel carbonate, the steps of which include:

[0044] Weigh 500.0 g of crude nickel carbonate and 2000.0 mL of deionized water into a 5 L reactor and stir at 300 rpm to form a suspension. Slowly add 625.0 g of glacial acetic acid, controlling the addition rate to keep the temperature below 60 °C, and continue stirring for 3.0 h until no more bubbles are generated, obtaining a nickel acetate solution. Add 25.0 g of hierarchical porous titanium silicate molecular sieve-supported bimetallic nanoclusters to this solution, stir at 150 rpm for 4.0 h at 45.0 °C, then let stand for 1.0 h. Filter through a 5 μm filter membrane to obtain a purified solution, and collect the used hierarchical porous titanium silicate molecular sieve-supported bimetallic nanoclusters for later use. The purified solution was transferred to an evaporator and concentrated to approximately 650 mL at 70.0 °C and -0.09 MPa to obtain a supersaturated solution. This solution was then transferred to a crystallization vessel and cooled to 15.0 °C at a programmed rate of 10.0 °C / h. After crystallization for 1.5 h, wet nickel acetate crystals were obtained by centrifugation at 4000 rpm for 20 min. 2.5 g of bimetallic nanoclusters supported on hierarchical porous titanium-silicon molecular sieves was added to the separated mother liquor. After stirring for 2.0 h, the mixture was filtered to obtain secondary crystals. The two crystals were combined and vacuum dried at 50.0 °C and -0.1 MPa for 5.0 h to obtain high-purity nickel acetate product.

[0045] The preparation process of bimetallic nanoclusters supported on hierarchical porous titanium-silicon molecular sieves is as follows: 50.0 g of titanium-silicon molecular sieves were placed in a muffle furnace and calcined at 550 °C for 4.0 h at a rate of 5 °C / min under air atmosphere. After cooling to room temperature, 500.0 mL of 10% hexadecyltrimethylammonium bromide aqueous solution was added, and the mixture was stirred at 200 rpm for 28.0 h in a water bath at 80.0 °C. After filtration, the solid product was washed with deionized water until neutral, and then immersed in 250.0 mL of 5% polyethylene oxide-polypropylene oxide block copolymer ethanol solution. The mixture was ultrasonically treated for 30 min, filtered again, and vacuum dried at 40.0 °C for 12.0 h to obtain the carrier precursor. Dissolve 2.5 g palladium chloride and 4.2 g copper nitrate in 400.0 mL of deionized water, add 25.0 g of carrier precursor, stir at 100 rpm for 13.0 h at 35.0 °C, then slowly add 300.0 mL of 0.1 mol / L sodium borohydride aqueous solution, reduce under nitrogen protection for 2.0 h, filter, and wash three times with nitrogen-saturated deionized water. The obtained material was immersed in 250.0 mL of a 3% (w / w) octadecyltrichlorosilane-toluene solution and treated under reflux for 7.0 h. After filtration, it was washed three times each with toluene and ethanol. The material was then redispersed in 500.0 mL of an ammonia-ammonium chloride buffer solution with pH=8.5 and aged in a water bath at 80.0 °C for 7.0 h. After filtration, it was vacuum dried at 60.0 °C for 24.0 h. Finally, the material was treated in a nitrogen mixture containing 5% hydrogen at a temperature of 3 °C / min to 300 °C for 3.0 h. After cooling to room temperature, it was equilibrated in an environment with 45% relative humidity for 24.0 h to obtain the final material.

[0046] Example 2

[0047] This embodiment provides a method for preparing high-purity nickel acetate from crude nickel carbonate, the steps of which include:

[0048] Weigh 400.0 g of crude nickel carbonate and 1600.0 mL of deionized water into a 4 L reactor and stir at 280 rpm to form a suspension. Slowly add 500.0 g of glacial acetic acid, controlling the addition rate to keep the temperature below 60 °C, and continue stirring for 2.5 h until no more bubbles are generated, yielding a nickel acetate solution. Add 20.0 g of hierarchical porous titanium silicate molecular sieve-supported bimetallic nanoclusters to this solution, and stir at 140 rpm for 5.0 h at 44.0 °C, then let stand for 1.2 h. Filter through a 5 μm filter membrane to obtain a purified solution, and collect the used hierarchical porous titanium silicate molecular sieve-supported bimetallic nanoclusters for later use. The purified solution was transferred to an evaporator and concentrated to approximately 520 mL at 65.0 °C and -0.08 MPa to obtain a supersaturated solution. This solution was then transferred to a crystallization vessel and cooled to 14.0 °C at a programmed rate of 8.0 °C / h. After crystallization for 2.0 h, the solution was centrifuged at 3800 rpm for 25 min to obtain wet nickel acetate crystals. 1.5 g of bimetallic nanoclusters supported on a hierarchical porous titanium-silicon molecular sieve was added to the separated mother liquor. After stirring for 2.5 h, the mixture was filtered to obtain secondary crystals. The two crystals were combined and vacuum dried at 48.0 °C and -0.1 MPa for 6.0 h to obtain high-purity nickel acetate product.

[0049] The preparation process of bimetallic nanoclusters supported on hierarchical porous titanium-silicon molecular sieves is as follows: 40.0 g of titanium-silicon molecular sieves were placed in a muffle furnace and calcined at 545 °C for 4.5 h at a rate of 5 °C / min under air atmosphere. After cooling to room temperature, 400.0 mL of 10% hexadecyltrimethylammonium bromide aqueous solution was added, and the mixture was stirred at 180 rpm for 30.0 h in a water bath at 78.0 °C. After filtration, the solid product was washed with deionized water until neutral, and then immersed in 200.0 mL of 5% polyethylene oxide-polypropylene oxide block copolymer ethanol solution. The mixture was ultrasonically treated for 35 min, filtered again, and vacuum dried at 38.0 °C for 14.0 h to obtain the carrier precursor. Dissolve 2.0 g palladium chloride and 3.4 g copper nitrate in 320.0 mL deionized water, add 20.0 g of the carrier precursor, stir at 90 rpm for 14.0 h at 34.0 °C, then slowly add 280.0 mL of 0.1 mol / L sodium borohydride aqueous solution, reduce under nitrogen protection for 2.5 h, filter, and wash three times with nitrogen-saturated deionized water. The obtained material was immersed in 200.0 mL of a 3% (w / w) octadecyltrichlorosilane-toluene solution and treated under reflux for 6.0 h. After filtration, it was washed three times each with toluene and ethanol. The material was then redispersed in 400.0 mL of an ammonia-ammonium chloride buffer solution with pH=8.4 and aged in a water bath at 78.0 °C for 8.0 h. After filtration, it was vacuum dried at 58.0 °C for 26.0 h. Finally, the material was treated in a nitrogen mixture containing 5% hydrogen at a temperature increased to 295 °C at 3 °C / min for 4.0 h. After cooling to room temperature, it was equilibrated in an environment with 40% relative humidity for 28.0 h to obtain the final material.

[0050] Example 3

[0051] This embodiment provides a method for preparing high-purity nickel acetate from crude nickel carbonate, the steps of which include:

[0052] Weigh 600.0 g of crude nickel carbonate and 2400.0 mL of deionized water into a 6 L reactor and stir at 320 rpm to form a suspension. Slowly add 750.0 g of glacial acetic acid, controlling the addition rate to keep the temperature below 60 °C, and continue stirring for 3.5 h until no more bubbles are generated, yielding a nickel acetate solution. Add 30.0 g of hierarchical porous titanium silicate molecular sieve-supported bimetallic nanoclusters to this solution, stir at 160 rpm for 3.0 h at 46.0 °C, then let stand for 0.8 h. Filter through a 5 μm filter membrane to obtain a purified solution, and collect the used hierarchical porous titanium silicate molecular sieve-supported bimetallic nanoclusters for later use. The purified solution was transferred to an evaporator and concentrated to approximately 780 mL at 75.0 °C and -0.10 MPa to obtain a supersaturated solution. This solution was then transferred to a crystallizer and cooled to 16.0 °C at a programmed rate of 12.0 °C / h. After crystallization for 1.0 h, wet nickel acetate crystals were obtained by centrifugation at 4200 rpm for 15 min. 3.0 g of bimetallic nanoclusters supported on hierarchical porous titanium-silicon molecular sieves was added to the separated mother liquor. After stirring for 1.5 h, the mixture was filtered to obtain secondary crystals. The two crystals were combined and vacuum dried at 52.0 °C and -0.1 MPa for 4.0 h to obtain high-purity nickel acetate product.

[0053] The preparation process of bimetallic nanoclusters supported on hierarchical porous titanium-silicon molecular sieves is as follows: 60.0 g of titanium-silicon molecular sieves were placed in a muffle furnace and calcined at 555 °C for 3.5 h at a rate of 5 °C / min under air atmosphere. After cooling to room temperature, 600.0 mL of 10% hexadecyltrimethylammonium bromide aqueous solution was added, and the mixture was stirred at 220 rpm for 24.0 h in a water bath at 82.0 °C. After filtration, the solid product was washed with deionized water until neutral, and then immersed in 300.0 mL of 5% polyethylene oxide-polypropylene oxide block copolymer ethanol solution. The mixture was ultrasonically treated for 25 min, filtered again, and vacuum dried at 42.0 °C for 10.0 h to obtain the carrier precursor. Dissolve 3.0 g palladium chloride and 5.0 g copper nitrate in 480.0 mL deionized water, add 30.0 g of the carrier precursor, stir at 110 rpm for 12.0 h at 36.0 °C, then slowly add 350.0 mL of 0.1 mol / L sodium borohydride aqueous solution, reduce under nitrogen protection for 1.5 h, filter, and wash three times with nitrogen-saturated deionized water. The obtained material was immersed in 300.0 mL of a 3% (w / w) octadecyltrichlorosilane-toluene solution and treated under reflux for 8.0 h. After filtration, it was washed three times each with toluene and ethanol. The material was then redispersed in 600.0 mL of an ammonia-ammonium chloride buffer solution with pH=8.6 and aged in a water bath at 82.0 °C for 6.0 h. After filtration, it was vacuum dried at 62.0 °C for 22.0 h. Finally, the material was treated in a nitrogen mixture containing 5% hydrogen at a temperature of 3 °C / min to 305 °C for 2.0 h. After cooling to room temperature, it was equilibrated in an environment with 50% relative humidity for 20.0 h to obtain the final material.

[0054] Comparative Example 1

[0055] The specific implementation method is the same as in Example 1, except that 500.0g of crude nickel carbonate and 2000.0mL of deionized water are weighed and added to a 5L reactor, and stirred at 300rpm to form a suspension. 625.0g of glacial acetic acid is slowly added, controlling the addition rate to keep the temperature below 60℃, and the reaction is continued for 3.0h until no bubbles are generated, resulting in a nickel acetate solution. Without any purification treatment, the solution is directly transferred to an evaporator and concentrated to a volume of approximately 650mL at 70.0℃ and -0.09MPa to obtain a supersaturated solution. This solution is then transferred to a crystallization vessel and cooled to 15.0℃ at a programmed rate of 10.0℃ / h. After crystallization for 1.5h, wet nickel acetate crystals are obtained by centrifugation at 4000rpm for 20min. The mother liquor is discarded directly, and the wet crystals are vacuum dried at 50.0℃ and -0.1MPa for 5.0h to obtain the nickel acetate product.

[0056] Comparative Example 2

[0057] The specific implementation method is the same as in Example 1, except that 500.0 g of crude nickel carbonate and 2000.0 mL of deionized water are weighed and added to a 5 L reactor, and stirred at 300 rpm to form a suspension. 625.0 g of glacial acetic acid is slowly added, controlling the addition rate to keep the temperature below 60°C, and the reaction is continued for 3.0 h until no bubbles are generated, yielding a nickel acetate solution. 25.0 g of unmodified titanium-silicon molecular sieve-supported bimetallic nanoclusters is added to this solution. This material only completes the precursor preparation and bimetallic loading steps, without octadecyltrichlorosilane surface modification. The mixture is stirred at 150 rpm at 45.0°C for 4.0 h, then allowed to stand for 1.0 h, and filtered through a 5 μm filter membrane to obtain a purified solution. Subsequent concentration, crystallization, centrifugation, and drying steps are exactly the same as in Example 1, yielding the nickel acetate product.

[0058] Comparative Example 3

[0059] The specific implementation method is the same as in Example 1, except that 500.0 g of crude nickel carbonate and 2000.0 mL of deionized water are weighed and added to a 5 L reactor, and stirred at 300 rpm to form a suspension. 625.0 g of glacial acetic acid is slowly added, controlling the addition rate to keep the temperature below 60°C, and the reaction is continued for 3.0 h until no bubbles are generated, yielding a nickel acetate solution. 25.0 g of titanium-silicon molecular sieve material loaded only with palladium is added to this solution. This material is prepared using only 4.2 g of palladium chloride without adding copper nitrate. Other preparation steps are the same as in Example 1. The mixture is stirred at 150 rpm for 4.0 h at 45.0°C, then allowed to stand for 1.0 h, and filtered through a 5 μm filter membrane to obtain a purified solution. Subsequent concentration, crystallization, centrifugation, and drying steps are exactly the same as in Example 1, yielding the nickel acetate product.

[0060] Performance testing

[0061] The high-purity nickel acetate obtained from the crude nickel carbonate preparations of Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing according to the following methods, which included the following steps: Nickel acetate content was determined by chemical titration: 0.5000g of sample was accurately weighed and placed in a 250mL Erlenmeyer flask, dissolved in 100mL of deionized water, and 0.2g of ammonium purpurate indicator was added. Titration was performed with 0.0500mol / L disodium ethylenediaminetetraacetate standard solution until the solution changed from yellow to purple-red. The titration was repeated three times in parallel, and the average value was taken. Metal impurity content was determined by inductively coupled plasma mass spectrometry: 0.1000g of sample was accurately weighed and placed in a 50mL volumetric flask, diluted to volume with 5% nitric acid solution, filtered through a 0.22μm polyethersulfone membrane, and detected using an Agilent 7900 ICP-MS equipped with an SC-FAST automated sample introduction system. Internal standard calibration was used, with indium as the internal standard. The instrument detection limit was 0.01μg / L. Moisture content was determined using the Karl Fischer coulometric method: 1.000 g of sample was dissolved in 10 mL of anhydrous methanol, and the solution was determined using a Mettler Toledo C30S moisture analyzer with HYDRANAL-Coulomat AG electrolyte at a stirring speed of 800 rpm until the endpoint. Water-insoluble matter was determined using the gravimetric method: 5.000 g of sample was dissolved in 100 mL of deionized water, filtered through a G4 sintered glass crucible pre-weighed at 105 °C, and the residue was washed three times with 50 mL of hot deionized water and dried to constant weight in an oven at 105 °C. Sulfate content was determined using the barium sulfate turbidimetric method: 1.000 g of sample was dissolved in 50 mL of deionized water, 5 mL of 3 mol / L hydrochloric acid solution was added, the mixture was boiled, and then 5 mL of 10% barium chloride solution was slowly added. The absorbance was measured at a wavelength of 420 nm. The chloride content was determined using the silver nitrate colorimetric method: 1.000g of sample was dissolved in 50mL of deionized water, 2mL of nitric acid solution was added, followed by 2mL of 0.1mol / L silver nitrate solution. The absorbance was measured at 440nm using a UV-Vis spectrophotometer. For the ammonia dissolution test, 2.000g of sample was dissolved in 20mL of 10% ammonia solution, allowed to stand for 30 minutes, and the precipitation was observed. The modified material's cyclic performance was tested: 10.00g of the modified material was used for each adsorption experiment. After adsorption, it was regenerated with 100mL of 0.5mol / L hydrochloric acid solution at room temperature for 1 hour. After washing until neutral, the material was reused, and the impurity removal rate was recorded at the 5th cycle.

[0062] Test results:

[0063] Table 1: Test results of each embodiment and comparative example

[0064] Test Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Nickel acetate content / % 99.3 99.1 99.4 96.2 97.8 97.5 Moisture / % 0.08 0.09 0.07 0.35 0.21 0.24 Water-insoluble matter / % 0.003 0.004 0.003 0.025 0.012 0.015 Cobalt content / ppm 5 7 4 42 25 33 Iron content / ppm 3 4 2 28 15 18 Lead content / ppm 2 3 2 15 8 11 Zinc content / ppm 4 5 3 35 20 26 Copper content / ppm 1 2 1 22 12 16 Sulfate / ppm 0.003 0.004 0.003 0.025 0.015 0.018 Chloride content / % 0.002 0.003 0.002 0.020 0.012 0.015 Ammonia dissolution test qualified qualified qualified Unqualified qualified qualified Iron removal rate / % 98.5 98.2 98.7 - 75.3 82.6 Copper removal rate / % 99.1 98.8 99.3 - 68.7 79.4 Zinc removal rate / % 98.3 97.9 98.5 - 72.1 80.8 Cobalt removal rate / % 97.8 97.5 98.1 - 70.5 78.3 Lead removal rate / % 98.7 98.4 98.9 - 73.8 81.2

[0065] As shown in Table 1, based on a comprehensive analysis of the performance test data, Examples 1-3 comprehensively solved the technical problems that this invention aims to overcome compared to Comparative Examples 1-3. Regarding product quality, the nickel acetate content in the Examples consistently exceeded 99%, significantly better than the 96.2% in Comparative Example 1. The contents of key impurities Co, Fe, Pb, Zn, and Cu were all controlled below 10 ppm, meeting electronic-grade standards. In contrast, the content of similar impurities in Comparative Example 1 exceeded the standard by several to tens of times, proving that this invention successfully achieved the core objective of deep purification. In terms of process efficiency, the modified materials used in the Examples exhibited excellent cycle stability, maintaining a removal rate of over 97% for each metal impurity even after the 5th cycle. In contrast, Comparative Example 2, lacking surface hydrophobic modification, saw its removal rate plummet to around 70%, confirming the crucial role of hydrophobic modification in maintaining the stability of the material in an acidic environment. Comparative Example 3, using a single-metal Pd material, achieved a removal rate of only about 80%, highlighting the synergistic adsorption advantages of the Cu-Pd bimetallic structure. In terms of techno-economic efficiency, the embodiment achieves efficient resource utilization through mother liquor recycling and material regeneration, increasing the product yield by approximately 9% compared to Comparative Example 1, and avoiding the complex operations of traditional multi-step purification processes. Regarding environmental friendliness, the water-insoluble matter, sulfate, and chloride content of the product from the embodiment are significantly lower than those of the comparative example, the ammonia dissolution test is fully qualified, and the overall process achieves near-zero wastewater discharge. In summary, this invention, through innovative material design and process optimization, simultaneously overcomes the four major technical challenges of traditional methods: purity bottleneck, process complexity, high cost, and environmental pollution, providing a complete solution for the high-value utilization of crude nickel carbonate.

[0066] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing high purity nickel acetate from crude nickel carbonate, characterized in that, The method comprises the following steps: S1, crude nickel carbonate and deionized water are added into a reaction kettle and stirred to obtain a suspension; glacial acetic acid is added into the suspension; and the reaction is continuously stirred to obtain a nickel acetate solution; S2, the multi-level pore titanium silicalite supported bimetallic nanocluster material is added into the nickel acetate solution and stirred at 44-46 DEG C; then, the solution is left to stand and filtered to obtain a purified nickel acetate solution; and the multi-level pore titanium silicalite supported bimetallic nanocluster material is collected and recycled after regeneration treatment; S3, the purified nickel acetate solution is transferred into an evaporator and concentrated at 65-75 DEG C to obtain a supersaturated nickel acetate solution; the supersaturated nickel acetate solution is transferred into a crystallization kettle and cooled to 14-16 DEG C; after incubation and crystal growth, solid-liquid separation is performed by a centrifuge to obtain wet nickel acetate crystals and a centrifuged mother liquor; S4, the multi-level pore titanium silicalite supported bimetallic nanocluster material is added into the centrifuged mother liquor and stirred; then, the solution is filtered to obtain wet nickel acetate crystals; and the wet nickel acetate crystals obtained in steps S3 and S4 are combined and dried in a vacuum drying oven at 48-52 DEG C.

2. The method of producing high purity nickel acetate from crude nickel carbonate according to claim 1, characterized in that, In step S1, the stirring reaction is continuously performed for 2-4 h.

3. The method for preparing high-purity nickel acetate from crude nickel carbonate according to claim 1, characterized in that, In step S2, the stirring is performed at 44-46 DEG C for 3-5 h.

4. The method for preparing high-purity nickel acetate from crude nickel carbonate according to claim 1, characterized in that, In step S3, the incubation and crystal growth are performed for 1-2 h.

5. The method for preparing high-purity nickel acetate from crude nickel carbonate according to claim 1, characterized in that, In step S4, the drying is performed at 48-52 DEG C for 4-6 h.

6. The process for the preparation of high purity nickel acetate from crude nickel carbonate according to any one of claims 1 to 5, characterized in that, The preparation steps of the multi-level pore titanium silicalite supported bimetallic nanocluster material comprise: A1, the titanium silicalite is placed in a muffle furnace, calcined at 545-555 DEG C under an air atmosphere to obtain a calcined sample; the calcined sample is cooled to room temperature, an aqueous solution of cetyltrimethylammonium bromide is added, and the mixture is stirred in a 78-82 DEG C water bath; the solid product is obtained after filtration, washed with deionized water until neutral, immersed in a polyethylene oxide-polypropylene oxide block copolymer ethanol solution, and ultrasonically treated; the solid product is again filtered and dried in a 38-42 DEG C vacuum drying oven to obtain a multi-level pore titanium silicalite support precursor; A2, palladium chloride and copper nitrate are dissolved in deionized water to obtain a metal salt solution; the multi-level pore titanium silicalite support precursor is added into the metal salt solution and stirred at 34-36 DEG C; then, an aqueous sodium borohydride solution is added, and a reduction reaction occurs under nitrogen protection to obtain a reaction mixture; the reaction mixture is filtered and washed with deionized water saturated with nitrogen to obtain a bimetallic nanocluster supported material; A3, the bimetallic nanocluster supported material is immersed in a toluene solution of octadecyltrichlorosilane and treated under reflux conditions; the material is filtered and washed with toluene and ethanol alternately to obtain a washed bimetallic nanocluster supported material; the washed bimetallic nanocluster supported material is redispersed in an ammonia chloride buffer solution with a pH of 8.4-8.6, and the mixture is aged in a 78-82 DEG C water bath to obtain a mixture; the mixture is filtered and dried in a 58-62 DEG C vacuum drying oven to obtain a surface hydrophobic modified multi-level pore titanium silicalite supported bimetallic nanocluster material; A4, the surface hydrophobic modified hierarchical pore titanosilicate zeolite loaded bimetallic nanocluster material is treated in hydrogen-nitrogen mixed gas, heated to 295-305°C; cooled to room temperature; and equilibrated in an environment with relative humidity of 40-50%.

7. The method for preparing high-purity nickel acetate from crude nickel carbonate according to claim 6, characterized in that, In step A1, the stirring time in the 78-82°C water bath is 24-30h.

8. The process for preparing high purity nickel acetate from crude nickel carbonate as claimed in claim 6 wherein, In step A2, the molar ratio of palladium chloride and copper nitrate is (1.5-1.7):1; the stirring time at 34-36°C is 12-14h.

9. The process for preparing high purity nickel acetate from crude nickel carbonate as claimed in claim 6 wherein, In step A3, the treatment time under reflux condition is 6-8h.

10. The process for preparing high purity nickel acetate from crude nickel carbonate as claimed in claim 6 wherein, In step A4, the treatment time at 295-305°C is 2-4h.