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CN-121974403-A - Preparation method of 6N-grade high-purity ammonium perrhenate based on chromatographic separation and directional crystallization

CN121974403ACN 121974403 ACN121974403 ACN 121974403ACN-121974403-A

Abstract

The invention discloses a preparation method of 6N-grade high-purity ammonium perrhenate based on chromatographic separation and directional crystallization. The method aims at solving the technical bottleneck that the conventional process is difficult to effectively remove trace metal impurities similar to rhenium ion in nature so as to reach the purity of 6N. The method comprises the core steps of (1) dissolving and preprocessing an industrial-grade ammonium rhenate raw material, (2) separating by adopting an ion exchange chromatographic column filled with chromatographic filler modified by specific functional groups, and realizing accurate separation by utilizing the difference of affinities of different ions and the filler, (3) introducing a crystallization inducer, and obtaining high-purity crystals through directional crystallization controlled by procedural cooling and evaporation. The invention combines high selectivity and high efficiency of chromatographic separation with purification amplification effect of directional crystallization, integrates on-line mass spectrum monitoring and feedback control, realizes process flow intellectualization and high stability of product purity, and is particularly suitable for being used as a high-performance metal rhenium powder raw material and a high-end petrochemical catalyst precursor.

Inventors

  • ZHONG YU
  • ZHANG YANGYING

Assignees

  • 诸暨弘德新材料有限公司

Dates

Publication Date
20260505
Application Date
20260310

Claims (6)

  1. 1. The preparation method of the 6N-grade high-purity ammonium perrhenate based on chromatographic separation and directional crystallization is characterized by comprising the following steps of: (1) Raw material pretreatment, namely dissolving industrial grade ammonium rhenate in ultrapure water to prepare saturated or nearly saturated solution, and filtering the solution through a microporous filter membrane with the diameter of 0.22 mu m to obtain clarified feed liquid; (2) Separating and purifying by chromatography, namely pumping the feed liquid obtained in the step (1) into an ion exchange chromatographic column filled with a chromatographic separation medium for separation, wherein the chromatographic separation medium is chelate resin with iminodiacetic acid groups or aminophosphonic acid groups or ultra-macroporous anion exchange resin designed by specific pore diameters; (3) Collecting the eluent of the high-purity ammonium perrhenate in the step (2), adding a crystallization inducer accounting for 0.01-0.1% of the total mass of the solution, then placing the eluent in a programmed cooling crystallizer, slowly cooling at a rate of 0.1-0.5 ℃ per hour, and assisting in controllable reduced pressure evaporation to induce the directional growth of the ammonium perrhenate crystals; (4) Separating and drying the crystals, namely separating the crystals obtained in the step (3) in a centrifugal or suction filtration mode, spraying and washing the crystals by adopting ultrapure water, and then drying the crystals to constant weight in a vacuum drying oven under the protection of high-purity nitrogen at 80-100 ℃; (5) And (5) ultra-clean packaging, namely transferring the dried high-purity ammonium perrhenate crystals into a fluorinated plastic bottle in a hundred-grade ultra-clean workbench, and filling high-purity argon gas for sealing and preserving.
  2. 2. The method according to claim 1, wherein in the step (2), the chromatographic separation process integrates on-line inductively coupled plasma mass spectrometer to monitor effluent in real time, and when the concentration of target impurity ions is detected to exceed a preset threshold, the system automatically switches the flow path to guide the unqualified fraction into the secondary collection tank, so as to ensure the purity of the product in the main collection tank.
  3. 3. The preparation method of claim 1, wherein in the step (2), the eluting solution is a mixed system of ultrapure ammonia water and ultrapure ammonium nitrate solution, and the pH value is accurately adjusted to be changed within the range of 4.0-9.0 by an intelligent control system so as to realize the step elution of impurity ions with different properties.
  4. 4. The method of claim 1, wherein in step (3), the crystallization inducer is a nano-scale high purity ammonium perrhenate seed crystal, or an organic template agent having a similar lattice parameter.
  5. 5. The method of claim 1, wherein in step (3), the programmable temperature-reducing crystallizer is equipped with a laser particle sizer and an imaging system, monitors the nucleation and growth process of crystals in real time, adjusts the temperature-reducing and evaporation rate by feedback control, suppresses secondary nucleation, and promotes the formation of large-size, high-integrity single crystals.
  6. 6. A high purity ammonium perrhenate prepared by the process of any one of claims 1-5, characterized by a purity of not less than 99.9999% (6N), wherein the individual content of critical impurity elements K, na, ca, mg, fe, cu, ni, pb, mo, W is less than 0.1ppm.

Description

Preparation method of 6N-grade high-purity ammonium perrhenate based on chromatographic separation and directional crystallization Technical Field The invention belongs to the technical field of high-purity inorganic compound preparation, and particularly relates to a method for synthesizing high-purity ammonium perrhenate, which is suitable for preparing high-purity metal rhenium powder for semiconductors and aerospace and preparing a high-performance petroleum reforming catalyst. Background Ammonium perrhenate is the most important precursor for preparing metallic rhenium. Because of its high melting point, excellent wear resistance, corrosion resistance and catalytic activity, metallic rhenium is widely used in high-temperature alloys for aerospace engines, electronics industry and petrochemical catalysts. In particular, as a petroleum catalytic reforming catalyst, the performance of the rhenium-based catalyst is closely related to the purity of ammonium perrhenate raw materials, and trace alkali metal (K, na) or heavy metal impurities (Fe, cu, pb) can obviously poison the active center of the catalyst, so that the selectivity and the service life of the catalyst are reduced. The purity requirements for high purity rhenium powder for sputter targets are more stringent, typically reaching levels of 5N (99.999%) and even 6N (99.9999%). Currently, the main methods for industrially producing high-purity ammonium perrhenate include multiple recrystallization, solvent extraction, and conventional ion exchange. The multiple recrystallization method has simple operation, but has limited effect of removing impurities (such as potassium and sodium salt) co-crystallized with rhenium, low efficiency and difficulty in reaching the purity of 6N. Although the solvent extraction method has large treatment capacity, organic solvent residues are easy to introduce, and the separation selectivity of certain specific impurities is poor. The conventional ion exchange method mostly adopts strong acid or strong alkali resin, and can remove most of impurities, but has an unsatisfactory separation effect on anions (such as MoO 4 & lt- & gt) with the radius and charge similar to those of ReO 4 & lt- & gt, and has the risk of cross contamination. Therefore, developing a new technology which can efficiently and accurately remove various trace impurities, has stable and controllable process flow and is suitable for large-scale production of 6N-grade high-purity ammonium perrhenate becomes a key problem to be solved in the field. Disclosure of Invention The purpose of the invention is that: overcomes the defects of the prior art and provides a preparation method of 6N-grade high-purity ammonium perrhenate which has high purity, advanced process and strong controllability and is suitable for industrial production. The invention adopts the technical scheme that: the core of the preparation method of the 6N-grade high-purity ammonium perrhenate is that a high-selectivity chromatographic separation technology and an accurate-control directional crystallization technology are integrated and innovated, and the preparation method specifically comprises the following procedures: 1. raw material pretreatment, namely selecting qualified industrial grade ammonium rhenate as a raw material, dissolving the ammonium rhenate with ultrapure water (resistivity is more than or equal to 18.2MΩ & cm), and filtering to remove insoluble impurities to obtain clean feed liquid. 2. Chromatographic separation and purification, which is an innovative key step. A chromatographic column filled with high-performance chelating resin or extra-macroporous anion exchange resin is used. Chelate resins (such as iminodiacetic acid type) have extremely strong complexing ability for polyvalent metal cations (such as Fe3+, cu2+, ca2+, mg2+), whereas ultra-macroporous anion exchange resins are specially designed, the pore size of which allows free diffusion of anions such as ReO 4 -and MoO 4 -, etc., and with the small difference in affinity with resin functionalities, high-efficiency separation is achieved by gradient elution with precise control of pH. The system integrates on-line ICP-MS, and performs real-time analysis on effluent, so that intelligent judgment and collection of product fractions are realized, and purity is ensured. 3. And (3) directional crystallization, namely, collecting the high-purity solution to enter a crystallization process. Adding nanoscale high-purity seed crystal as inducer, and performing in a programmed cooling crystallizer. Optimal thermodynamic and kinetic conditions for crystal growth are provided by extremely slow cool down rates (e.g., 0.2 ℃ per hour) and controlled solvent evaporation. The process can effectively exclude impurities from entering crystal lattices (segregation effect), further purify products, generate large crystals with uniform granularity and regular morphology, and facilitate subsequent washing and reduce specific su