Substituted imidazole compound, rhenium extraction agent, preparation method of rhenium extraction agent and method for separating molybdenum and rhenium

Abstract

The invention provides a substituted imidazole compound, a rhenium extraction agent, a preparation method of the rhenium extraction agent and a method for separating molybdenum and rhenium, and relates to the technical field of hydrometallurgy. The structural formula of the substituted imidazole compound is shown in the specification. The substituted imidazole compound takes an imidazole ring as a molecular skeleton, the imidazole ring is modified through a substitution reaction, a plurality of aromatic ring functional groups are introduced, and the hydrophobic property, steric hindrance and electron density of a rhenium extraction agent are adjusted, so that the rhenium extraction agent is more favorable for being combined with ReO4 <-> to realize separation, and the water-phase solubility of the extraction agent is reduced, thereby reducing the dissolution loss of the extraction agent; a large-steric-hindrance aromatic ring is introduced to react with quaternization, an aliphatic chain is introduced to an N-active site, and the electrical property of an imidazole ring and the distribution condition of electron clouds are adjusted, so that a Z-bond network is formed in an organic phase and can be effectively bonded with perrhenic acid radical ions; lone pair electrons of the N-activation site and imidazole ring conjugated electron cloud cooperate with each other, so that perrhenate ions can be combined to the maximum extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy, and particularly relates to a substituted imidazole compound, a rhenium extractant, a preparation method thereof and a method for separating molybdenum and rhenium. BACKGROUND

[0002] Both molybdenum and rhenium are important strategic metals and are widely used in the fields of aerospace, electronics, chemical industry and the like. Due to the similar chemical properties of molybdenum and rhenium, especially the similar behaviors of their anion forms (such as MoO4 2- , ReO4 - ) in solution, the separation of similar elements molybdenum and rhenium becomes a difficulty in hydrometallurgy.

[0003] In the prior art, the separation methods of molybdenum and rhenium include solvent extraction, ion exchange, adsorption method and the like. Among them, the solvent extraction method is widely studied due to the large processing capacity, high efficiency and easy continuous operation. However, the existing extractants such as amines and phosphorus have certain effects, but still have problems such as low selectivity, need for pretreatment, large consumption of acid and alkali, high cost of extractant or environmental pollution. However, there are many problems in separating and purifying rhenium by using the solvent extraction method at present, for example, in the patent CN101220418B, TiO2 solid is used, and an ultrasonic adsorption method is used at room temperature to separate a solution containing rhenium. Although this method does not use organic solvents, a large amount of acid and alkali is needed to adjust the pH value; in the reference patent CN102251107B, the rhenium-containing raw material is mixed with an oxidizing agent in an alkaline environment at normal pressure, and after the reaction is completed, the reaction product is filtered, and the obtained filtrate is adsorbed by a strong alkaline anion exchange resin, and then the strong alkaline anion exchange resin is resolved. A large amount of oxidizing agent is needed in this process; in the reference patent CN118086704A, molybdenum calcine is used as raw material, molybdenum and rhenium in the molybdenum calcine are leached, molybdenum is leached at the same time to obtain a high-concentration sodium molybdate solution containing rhenium, the separation of molybdenum and rhenium in the high-concentration sodium molybdate solution is realized by ion exchange adsorption, and high-concentration ammonium rhenate solution is obtained by special ion exchange resolution process to enrich rhenium. The production requirement is high, which is not conducive to the popularization of industry.

[0004] In summary, the existing solvent extraction method has problems such as low extraction efficiency, high cost of extractant and large amount of wastewater discharge, which seriously limits its application in industrialization. Therefore, it is a technical problem to be solved in the field to develop a main component of a molybdenum-rhenium separation extractant which is efficient, has good selectivity and is environmentally friendly. SUMMARY

[0005] The present application aims to provide a substituted imidazole compound, a rhenium extractant, a preparation method thereof and a method for separating molybdenum and rhenium, so as to solve the above problems.

[0006] To achieve the above object, the first aspect of the present application provides a substituted imidazole compound, whose structural formula is: .

[0007] The second aspect of the present application provides a preparation method of the substituted imidazole compound, comprising: second mixing, first reaction, solid-liquid separation are performed on diphenyl ketone, benzaldehyde, ammonium acetate, sucrose and an organic solvent to obtain 2,4,5-triphenyl imidazole; third mixing, second reaction, reduced pressure distillation and first purification are performed on the 2,4,5-triphenyl imidazole, iodo octane, NaH and tetrahydrofuran to obtain 1-octyl-2,4,5-triphenyl imidazole; fourth mixing, third reaction, reduced pressure distillation and second purification are performed on the 1-octyl-2,4,5-triphenyl imidazole, dimethyl sulfate and acetonitrile to obtain the substituted imidazole compound.

[0008] Optionally, the preparation method of the substituted imidazole compound satisfies at least one of the following conditions: (1) the mass ratio of the diphenyl ketone, the benzaldehyde, the ammonium acetate, the sucrose and the organic solvent is 1-10:1-10:1-10:0-2; (2) the mass ratio of the 2,4,5-triphenyl imidazole, the iodo octane and the NaH is 10-20:10-20:0.5-2.5; (3) the mass ratio of the 1-octyl-2,4,5-triphenyl imidazole and the dimethyl sulfate is 1-4:1; (4) the first eluent is used for the first purification, and the first eluent comprises petroleum ether and ethyl acetate; the volume ratio of the petroleum ether and the ethyl acetate is 1-5:1-5; (5) the second eluent is used for the second purification, and the second eluent comprises dichloromethane and methanol; the volume ratio of the dichloromethane and the methanol is 1-70:1-10; (6) the temperature of the first reaction is 10-40℃, and the time is 24-72h; (7) the temperature of the second reaction is 40-80℃, and the time is 1-10h; (8) the temperature of the third reaction is 70-100℃, and the time is 2-10h.

[0009] The third aspect of the present application provides a rhenium extractant, whose raw materials, with a total volume of 100%, comprise: 5%-40% substituted imidazole compound, 10%-40% co-extraction agent, and the rest is diluent; The co-extraction agent is a neutral phosphorus-containing extraction agent and / or an acidic phosphorus-containing extraction agent. The substituted imidazole compound includes the substituted imidazole compound described above or a substituted imidazole compound prepared by the method for preparing the substituted imidazole compound described above.

[0010] Optionally, the rhenium extractant satisfies at least one of the following conditions: (1) The co-extractant is selected from one or more of tributyl phosphate, trioctyl phosphate and trioctylphosphine oxide; (2) The diluent is selected from one or more of kerosene, sulfonated kerosene, hexane, octane, dichloromethane, dichloroethane, chloroform, octanol, toluene and xylene.

[0011] The fourth aspect of this application provides a method for preparing the rhenium extractant, comprising: The raw materials are first mixed to prepare the product.

[0012] The fifth aspect of this application provides a method for separating molybdenum and rhenium, comprising: A fifth mixing of an acidic solution containing molybdenum and rhenium and a rhenium extractant yields a mixture; the mixture is then extracted and back-extracted to obtain a perrhenate solution and a molybdenum-containing solution. The rhenium extractant includes the rhenium extractant described above or the rhenium extractant prepared by the method described above.

[0013] Optionally, the method for separating molybdenum and rhenium satisfies at least one of the following conditions: (1) The acidic solution containing molybdenum and rhenium includes copper smelting waste acid and / or molybdenum concentrate acid leaching solution; (2) The pH value of the acidic solution containing molybdenum and rhenium is less than 7; (3) The concentration of rhenium in the acidic solution containing molybdenum and rhenium is 0.006-10 g / L and the concentration of molybdenum is 0.012-20 g / L.

[0014] Optionally, the method for separating molybdenum and rhenium satisfies at least one of the following conditions: (1) The extraction and back-extraction temperatures are each 20-25℃ and the extraction times are each 5-10 min; (2) The volume ratio of the organic phase to the aqueous phase in the mixture is 1-5:1-5.

[0015] Optionally, the organic phase obtained after extraction may be washed with a detergent before back-extraction; The detergent includes one or more of sulfuric acid, hydrochloric acid, and nitric acid; The mass concentration of the detergent is 0.001-50 g / L.

[0016] Optionally, the stripping agent used in the stripping process includes one or more of ammonia, sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate and ammonium bicarbonate. The mass concentration of the stripping agent is 1%-25%.

[0017] Compared with the prior art, the application has the following beneficial effects: The substituted imidazole compound provided by the application first uses an imidazole ring as a molecular skeleton, modifies the imidazole ring through a substitution reaction, introduces multiple aromatic ring functional groups, adjusts the hydrophobic properties, steric hindrance and electronic density of the rhenium extractant, and makes it more conducive to bonding with ReO4 - The combination realizes separation and reduces the water phase solubility of the rhenium extractant, thereby reducing the dissolution loss of the extractant; secondly, by introducing a large steric hindrance aromatic ring and a quaternary ammonium reaction, a fatty chain is introduced at the N-active site, the electrical properties and electron cloud distribution of the imidazole ring are adjusted, the Z bond network is formed in the organic phase, the imidazole ring can effectively bond with the perrhenate ion, at the same time, the lone pair electrons of the N-active site and the conjugated electron cloud of the imidazole ring cooperate with each other to maximize the bonding with the perrhenate ion; the rhenium extractant molecule has a macrocyclic conjugated structure, and the pi-pi stacking effect in the organic phase is conducive to improving the extraction performance of the extractant.

[0018] The preparation method of the substituted imidazole compound provided by the application has a delicate synthesis route, mild and controllable conditions, and uses a classical and efficient reaction step. The reaction conditions are mild, no harsh high temperature and high pressure environment is needed, the operation safety is high, the requirement for equipment is low, and the threshold and risk of industrial production are greatly reduced. The raw materials are easy to obtain and cost-effective. The selected raw materials are common chemicals on the market, widely available and low in cost, which is conducive to large-scale and low-cost preparation and has significant economic advantages. The reaction has good selectivity and high product purity. By accurately controlling the material ratio, temperature and time of each reaction and combining column chromatography and other purification methods, the occurrence of side reactions can be effectively inhibited, and high-purity target products can be successfully obtained. The functional group compatibility is strong, and the structure has large plasticity. The synthesis route has excellent functional group compatibility. By flexibly adjusting the aromatic ring substituent, the length and structure of the N-position fatty chain, the steric hindrance, electronic effect and hydrophobicity of the compound can be systematically regulated, thereby realizing directional optimization and "molecular customization" of the extraction performance, and showing strong structural plasticity and application expansion potential.

[0019] The rhenium extractant provided by the application is not a simple superposition of the functions of each component, but a perfect synergistic effect among the substituted imidazole compound, the synergistic agent and the diluent, which together construct an efficient, stable and highly selective extraction system. The substituted imidazole compound as the main extractant provides a unique molecular structure, which provides a unique molecular structure. -The high selectivity of ion recognition and bonding ability is the fundamental source of selectivity; the synergistic agent enhances the capture and fixation of target ions through its strong coordination ability, improves the extraction capacity and kinetic speed, and makes up for the possible insufficient saturated capacity of single main agent; the diluent provides an optimized physical platform and economic benefit for the whole extraction process, ensuring that the chemical functions of the former two can be efficiently and economically realized in industrial practice. In the organic phase, the cationic head of the substituted imidazole compound is combined with ReO4 - The weak interaction (such as dipole-dipole interaction) between the bulky aromatic ring system of the substituted imidazole compound and the synergistic agent molecules, and their compatibility with the diluent environment, jointly promote the formation of the ternary complex of “main agent-synergistic agent-target ion”. The complex structure is stable and highly hydrophobic, thereby realizing the efficient and complete transfer of rhenium from the aqueous phase to the organic phase. The suitable diluent and synergistic agent work together to effectively prevent the excessive self-aggregation or crystallization precipitation of the main extractant molecules in the organic phase, ensuring the chemical stability and performance reproducibility of the extractant during multiple cycles of use. The organic phase system formed by the three can effectively resist the interference of high acidity and impurity ions in the aqueous phase; and has extremely high rhenium selectivity and extraction efficiency under acidic conditions, without the need for pretreatment, and has strong resistance to impurity ion interference; it is especially suitable for complex copper smelting waste acid and molybdenum concentrate leaching solution systems, has easy stripping, recyclable rhenium extractant, simple process flow, low cost, environmental friendliness, and has significant industrial application value.

[0020] The preparation method of the rhenium extractant provided in the present application has a simple synthesis route.

[0021] The method for separating molybdenum and rhenium provided in the present application, the rhenium extractant is composed of a substituted imidazole compound, a synergistic agent and a diluent, the rhenium extractant is used for extracting a solution containing molybdenum and rhenium, and rhenium is preferentially extracted, so that efficient separation of molybdenum and rhenium is realized; the rhenium extractant does not need to be saponified or activated when used for extracting and separating rhenium, nor does it need to use acid, alkali or oxidizing agent, and the extraction rate and purity of rhenium are high, in addition, the rhenium extractant can be reused after stripping, which is green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope of the present application.

[0023] Figure 1 The nuclear magnetic hydrogen spectrum of the substituted imidazole compound provided for Example 1. DETAILED DESCRIPTION

[0024] Firstly, the scheme provided by the present application is explained in more detail, as follows: The present application provides a substituted imidazole compound, whose structural formula is as follows: .

[0025] It should be noted that the compound takes imidazole ring as the basic molecular skeleton, introduces multiple aromatic ring functional groups on the imidazole ring through electrophilic substitution reaction, thereby realizing systematic regulation of the hydrophobicity, spatial configuration and electron cloud density of the rhenium extractant. Such structural modification not only enhances the selective coordination ability of the extractant to perrhenate ions (ReO4 - ), but also significantly reduces the solubility of the extractant in inorganic aqueous phase, effectively inhibiting the solvent loss in the extraction process.

[0026] Further, by introducing aromatic ring structures with large steric hindrance in the molecule, the size screening effect on the coordination ions is realized, so that the smaller perrhenate ions can be efficiently recognized and bonded, thereby endowing the extractant with excellent selective extraction performance. In addition, by quaternary ammonium modification at the N-active site of the imidazole ring, flexible aliphatic chains are introduced, which can further adjust the electronic properties of the imidazole ring and the surrounding electron cloud distribution, enhance the electrostatic and coordination action with perrhenate ions. In this process, the synergistic effect of the lone pair of electrons on the N-active site and the conjugated π system of the imidazole ring can realize the maximum degree of combination with perrhenate ions.

[0027] The compound molecule has an extended macrocyclic conjugated structure, which can form ordered supramolecular assemblies through intermolecular π-π stacking in organic phase, which helps to further improve the stability and extraction efficiency of the extractant.

[0028] The second aspect of the present application provides a preparation method of a substituted imidazole compound, comprising: mixing diphenylglyoxime, benzaldehyde, ammonium acetate, sucrose and an organic solvent to obtain 2,4,5-triphenylimidazole; mixing the 2,4,5-triphenylimidazole, iodoctane, NaH and tetrahydrofuran to obtain 1-octyl-2,4,5-triphenylimidazole; mixing the 1-octyl-2,4,5-triphenylimidazole, dimethyl sulfate and acetonitrile to obtain the substituted imidazole compound.

[0029] In some embodiments, the preparation method of the substituted imidazole compound satisfies at least one of the following conditions: (1) the mass ratio of the benzophenone, the benzaldehyde, the ammonium acetate, the sucrose is 1-10:1-10:1-10:0-2; Optionally, the mass ratio of the benzophenone, the benzaldehyde, the ammonium acetate, the sucrose can be 1:1:1:0.1, 1:5:1:0.1, 1:10:1:0.1, 1:5:5:0.1, 1:5:10:0.1, 1:10:10:1, 1:5:5:2 or any value between 1-10:1-10:1-10:0-2; (2) the mass ratio of the 2,4,5-triphenyl imidazole, the iodo octane and the NaH is 10-20:10-20:0.5-2.5; Optionally, the mass ratio of the 2,4,5-triphenyl imidazole, the iodo octane and the NaH can be 10:10:0.5, 10:15:0.5, 15:20:0.5, 20:20:2.5 or any value between 10-20:10-20:0.5-2.5; (3) the mass ratio of the 1-octyl-2,4,5-triphenyl imidazole and the dimethyl sulfate is 1-4:1; Optionally, the mass ratio of the 1-octyl-2,4,5-triphenyl imidazole and the dimethyl sulfate can be 1:1, 2:1, 3:1, 4:1 or any value between 1-4:1; (4) the first purification is performed using a first eluent, the first eluent comprising petroleum ether and ethyl acetate; the volume ratio of the petroleum ether and the ethyl acetate is 1-5:1-5; Optionally, the volume ratio of the petroleum ether and the ethyl acetate can be 1:1, 1:2.5, 1:5, 2.5:1, 5:1, 5:2.5 or any value between 1-5:1-5; (5) the second purification is performed using a second eluent, the second eluent comprising dichloromethane and methanol; the volume ratio of the dichloromethane and the methanol is 1-70:1-10; Optionally, the volume ratio of the dichloromethane and the methanol can be 1:1, 10:1, 50:1, 70:1, 1:10, 70:10 or any value between 1-70:1-10; (6) the temperature of the first reaction is 10-40℃, the time is 24-72h; Optionally, the temperature of the first reaction can be 10℃, 20℃, 30℃, 40℃ or any value between 10-40℃, the time can be 24h, 30h, 40h, 50h, 60h, 72h or any value between 24-72h; (7) the temperature of the second reaction is 40-80℃, the time is 1-10h; Optionally, the temperature of the second reaction can be 40℃, 50℃, 60℃, 70℃, 80℃, or any value between 40-80℃, and the time can be 1h, 2h, 4h, 6h, 8h, 10h, or any value between 1-10h; (8) The temperature of the third reaction is 70-100℃, and the time is 2-10h.

[0030] Optionally, the temperature of the third reaction can be 70℃, 80℃, 90℃, 100℃, or any value between 70-100℃, and the time can be 2h, 4h, 6h, 8h, 10h, or any value between 2-10h.

[0031] The third aspect of the present application provides a rhenium extraction agent, the raw materials of which, accounting for 100% of the total volume, comprise: 5%-40% of a substituted imidazole compound, 10%-40% of a synergistic extraction agent, and the balance being a diluent; Optionally, the raw materials of the rhenium extraction agent, accounting for 100% of the total volume, can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any value between 5-40% of a substituted imidazole compound, and 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any value between 10-40% of a synergistic extraction agent; The synergistic extraction agent is a neutral phosphorus-containing extraction agent and / or an acidic phosphorus-containing extraction agent.

[0032] It should be noted that the high selectivity of the rhenium extraction agent is not due to a single mechanism, but is the result of the combined action of steric hindrance screening, electronic cloud synergistic matching, and solution chemical behavior regulation. Its molecular design cleverly utilizes the specific recognition mechanism of ReO4 - , while multiple barriers are set up from the spatial and electronic levels, effectively inhibiting the non-specific binding of competing ions such as molybdenum, thereby achieving efficient and highly selective separation of rhenium in complex systems.

[0033] 1. Spatial size screening effect, precise steric hindrance matching: perrhenate ion (ReO4 - ) and pertechnetate ion (TcO4 - ) have similar small-volume tetrahedral geometric configurations. The rhenium extraction agent molecule introduces a large steric aromatic ring functional group on the imidazole skeleton, constructing a specific "steric constraint cavity" around the molecular recognition site. This cavity only allows ReO4 - such small-volume, structurally symmetric tetrahedral anions to approach and bond, effectively excluding larger-volume or geometrically mismatched anions.

[0034] First, in typical acidic or near-neutral leaching solutions, molybdenum is usually in the form of polymeric isopoly acid anions (such as Mo8O26 4- It exists in the form of hydrated MoO3·xH2O colloids, etc. These molybdenum species are not only much larger in volume than ReO4, but also exist in other forms such as hydrated MoO3·xH2O colloids. - Furthermore, their configurations are mostly flat octahedral or complex polymer chain structures, which cannot effectively enter the narrow recognition cavity constructed by sterically hindered aromatic rings, thus being initially screened out in space, achieving primary selectivity based on molecular size and shape.

[0035] Secondly, the binding affinity of rhenium extractant to target ions fundamentally depends on the degree of matching between the former's electron cloud distribution and the latter's electron-accepting capacity. This is reflected in the binding affinity of Rhenium to ReO4. - Efficient bonding: Aliphatic chains are introduced into the N-active site of the imidazole ring through quaternization reaction, forming a positively charged quaternary ammonium salt center. This center works synergistically with the large π-conjugated system of the imidazole ring itself: (1) Electrostatic interaction, the quaternary ammonium salt cation and ReO4 - A strong Coulomb attraction occurs between anions, which is the initial driving physical bond; (2) Non-covalent bond coordination, ReO4 - As a weak hydrogen bond acceptor, ReO4 - As a negatively charged anion, it can form a Z-bond network with the charge-polarized CH bonds in the extractant molecule (especially the CH bonds adjacent to N). Furthermore, the delocalized π-electron clouds of the imidazole ring and aromatic substituents further disperse the positive charge of the organic cation, allowing it to react with ReO4. - Anionic-π interactions occur between the N-active sites, participating in the formation of the Z-bond network. The synergy between the lone pair electrons of the N-active site and the imidazole ring conjugated system greatly optimizes the electron cloud distribution, enabling the superposition and resonance of the aforementioned non-covalent interactions, thereby achieving the desired effect on ReO4. - Strong and stable bonding.

[0036] 2. As mentioned earlier, molybdenum species in solution typically have high charge densities (e.g., Mo8O). 26 4- They also have stronger coordination abilities. They tend to coordinate with hard Lewis bases (such as OH-) - CO3 2- Rhenium extractants may undergo strong coordination bonds or even hydrolysis reactions with oxygen or nitrogen atoms containing lone pairs of electrons. The recognition sites of rhenium extractants are based on weak non-covalent interactions and electrostatic attraction, rather than strong coordination bonds. This "soft" interaction mode is related to ReO4. - The "soft" base properties of rhenium are compatible, but not with the "hard" or "boundary" acid properties of molybdenum species. If forced, the strong electron-grabbing tendency of molybdenum species may lead to the destruction of the molecular structure of the rhenium extractant or the formation of stable precipitates that are difficult to back-extract. However, due to the selective steric hindrance of the rhenium extractant designed in this application, such unfavorable strong interactions are fundamentally prevented in advance.

[0037] 3. The hydrophobicity of the rhenium extractant molecule as a whole and the macrocyclic conjugated structure ensure its stable existence in the organic phase and the ordered aggregates formed by π-π stacking. This microenvironment greatly shields the interference of a large number of competitive anions (such as SO4 2- , Cl - , etc.) existing in the external aqueous phase. At the same time, ReO4 - can maintain its simple tetrahedral structure in a very wide pH range, and its chemical properties are stable and easy to be extracted. The solution chemistry behavior of molybdenum is extremely complex, its form changes dramatically with pH, and it is prone to hydrolysis and polymerization. This inherent instability further reduces the possibility of effective and specific interaction between molybdenum and the rhenium extractant.

[0038] It should also be noted that the synergistic agent plays a key synergistic function. First, it coordinates to enhance the extraction capacity. The phosphoryl group (P=O) in the synergistic agent molecule has strong electron-donating ability and can act as a Lewis base to interact with the perrhenate ion (ReO4 - ) or the substituted imidazole cation-ReO4 - ion pair to form a more stable and more hydrophobic mixed coordination complex, thereby significantly improving the saturation extraction capacity and extraction efficiency of rhenium; improving the phase separation behavior: the addition of the synergistic agent can effectively adjust the viscosity and density of the organic phase, promote the rapid and clear separation of the organic phase and the aqueous phase after extraction, reduce the entrainment loss, and improve the operation efficiency. Inhibit the formation of the third phase: under high load conditions, the synergistic agent helps to maintain the uniformity of the organic phase, preventing the formation of the third phase due to the aggregation of the extractant or the extractant, and ensuring the continuity and stability of the extraction process.

[0039] In addition, the diluent constitutes the main body of the continuous phase of the rhenium extractant, and its role is crucial, as follows: dissolution and dispersion: providing a good dissolution environment for substituted imidazole compounds and synergistic agents, ensuring uniform dispersion of each component molecule, forming a uniform and stable organic phase system; adjusting the physicochemical properties: by selecting diluents of different polarity and viscosity, the density, viscosity and surface tension of the organic phase can be overall controlled to meet the requirements of flowability, phase separation speed and other physical properties in industrial extraction process; reducing costs: the large amount of diluent used as a carrier effectively reduces the amount of high-cost main extractant (substituted imidazole compounds) and synergistic agent in unit volume of extractant, thereby having significant economic benefits.

[0040] In some embodiments, the rhenium extractant satisfies at least one of the following conditions: (1) the synergistic agent is selected from one or more of tributyl phosphate, trioctyl phosphate, and trioctylphosphine oxide; It should be noted that the neutral phosphorus-containing extractant selected in the present application, such as tributyl phosphate (TBP), trioctyl phosphate (TOP) or trioctylphosphine oxide (TOPO), is used as a synergistic extractant based on its unique molecular structure and physicochemical properties, which can produce excellent synergistic effect with the host compound. The specific reasons and beneficial effects are as follows: 1. Precise matching of molecular structure and performance, and optimized matching of coordination ability: the phosphoryl group (P=O) in the neutral phosphorus-containing extractant molecule is a strong Lewis base, and its lone pair of electrons can coordinate with perrhenate ion (ReO4 - ) or substituted imidazole cation-ReO4 - ion pair. Compared with other types of synergistic extractants (such as crown ethers or carboxylic acids), the electron-donating ability of this type of phosphorus-containing synergistic extractant is moderate, which can effectively enhance the binding to the target ion, and avoid the problems of difficult stripping or formation of irreversible complexes due to excessive coordination; suitable steric hindrance: TBP, TOP and other molecules have a moderate spatial structure, which can provide the necessary hydrophobicity without hindering the formation of effective ternary complexes with the host agent and target ion due to excessive steric hindrance; TOPO has slightly larger steric hindrance, but its stronger electron-donating ability compensates for this, which is suitable for systems that require higher extraction power. Compatibility with the host agent and synergistic mechanism: these neutral phosphorus-containing synergistic extractants are excellent metal extractants themselves, and their action mechanism (ion pair extraction and solvation) is highly complementary to the ion exchange mechanism of the substituted imidazole compounds in the present application. They can synergistically act on the extraction process, rather than competing or interfering with each other, thereby forming a "1+1>2" synergistic result; 2. Beneficial effects: comprehensive performance improvement, significantly improved extraction efficiency and saturation capacity, the addition of synergistic extractant can form more stable and more hydrophobic ternary complexes with substituted imidazole compounds and target ions, which significantly improves the rhenium loading capacity (saturation capacity) and extraction rate per unit volume of extractant. This enables efficient enrichment when dealing with low-concentration rhenium solutions, and reduces the amount of extractant when dealing with high-concentration solutions, thereby reducing costs and organic phase viscosity; enhanced extraction selectivity: the synergistic extractant preferentially reacts with the target ion ReO4 - and its ion pair with the substituted imidazole compound, while the polymeric anions of molybdenum or other impurity ions (such as SO4 2- , Cl -The coordination ability of the neutral phosphorus-containing synergistic agent is weak. The coordination selectivity is combined with the space size screening effect of the main agent to form a double guarantee for the selectivity of rhenium, further inhibiting the co-extraction of impurities such as molybdenum; and can improve the physical properties and operation stability of the organic phase, and inhibit the third phase: under high temperature or high load conditions, a single ionic liquid type extractant is easy to form a third phase (i.e. two organic phases) in the organic phase, resulting in operation failure. The addition of the neutral phosphorus-containing synergistic agent can effectively destroy the ordered aggregation of the complex, greatly inhibit or even completely eliminate the formation of the third phase, and ensure the continuity and stability of the extraction process. Promote phase separation: the synergistic agent can moderately reduce the viscosity of the organic phase, speed up the phase separation speed, reduce the entrainment of the aqueous phase in the organic phase, thereby improving the product purity and operation efficiency. Improve the stripping performance and the cycle life of the extractant: since the combination of the neutral phosphorus-containing synergistic agent and ReO4 - is a reversible weak coordination, the coordination bond can easily break when encountering a basic stripping agent (such as ammonia water, carbonate), thereby facilitating efficient and complete stripping of rhenium. This not only improves the recovery rate of rhenium, but also enables the substituted imidazole compound and the synergistic agent to quickly recover activity, ensuring the excellent cycle performance and long-term stability of the rhenium extraction agent; (2) the diluent is selected from one or more of kerosene, sulfonated kerosene, hexane, octane, dichloromethane, dichloroethane, chloroform, octanol, toluene, and xylene.

[0041] The fourth aspect of the present application provides a preparation method of the rhenium extraction agent, comprising: The raw materials are first mixed to obtain.

[0042] The fifth aspect of the present application provides a method for separating molybdenum and rhenium, comprising: The acid solution containing molybdenum and rhenium and the rhenium extraction agent are fifthly mixed to obtain a mixture; the mixture is extracted and stripped to obtain a perrhenate solution and a molybdenum-containing solution; It should be noted that the rhenium extraction agent is used for selectively extracting rhenium or molybdenum from an acid solution containing molybdenum and rhenium, and is particularly suitable for copper smelting contaminated acid and molybdenum concentrate acid leaching solution systems with high acidity and high impurity background. The above two systems are the most common rhenium-containing solution systems, and are more in line with actual application scenarios.

[0043] In some embodiments, the method for separating molybdenum and rhenium satisfies at least one of the following conditions: (1) the acid solution containing molybdenum and rhenium comprises copper smelting contaminated acid and / or molybdenum concentrate acid leaching solution; (2) the pH value of the acid solution containing molybdenum and rhenium is less than 7; Optionally, the pH value of the acid solution containing molybdenum and rhenium can be 0, 1, 2, 3, 4, 5, 6, or any value less than 7; (3) the concentration of rhenium element in the acid solution containing molybdenum and rhenium is 0.006-10 g / L, and the concentration of molybdenum element is 0.012-20 g / L.

[0044] Optionally, the concentration of rhenium element in the acid solution containing molybdenum and rhenium can be 0.006 g / L, 0.06 g / L, 0.6 g / L, 1 g / L, 5 g / L, 10 g / L or any value between 0.006-10 g / L, and the concentration of molybdenum element can be 0.012 g / L, 0.1 g / L, 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L or any value between 0.012-20 g / L.

[0045] In some embodiments, the method for separating molybdenum and rhenium satisfies at least one of the following conditions: (1) the temperature of the extraction and the stripping is independently 20-25℃, and the time is independently 5-10 min; Optionally, the temperature of the extraction and the stripping can be independently 20℃, 21℃, 22℃, 23℃, 24℃, 25℃ or any value between 20-25℃, and the time can be independently 5 min, 6 min, 7 min, 8 min, 9 min, 10 min or any value between 5-10 min; (2) the volume ratio of the organic phase to the aqueous phase in the mixture is 1-5:1-5.

[0046] Optionally, the volume ratio of the organic phase to the aqueous phase in the mixture can be 1:1, 1:2, 1:3, 1:4, 1:5, 2.5:1, 5:1 or any value between 1-5:1-5.

[0047] In some embodiments, before the stripping, the organic phase obtained after the extraction is washed with a detergent; The detergent comprises one or more of sulfuric acid, hydrochloric acid and nitric acid; The mass concentration of the detergent is 0.001-50 g / L.

[0048] Optionally, the mass concentration of the detergent can be 0.001 g / L, 0.01 g / L, 0.1 g / L, 1 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L or any value between 0.001-50 g / L.

[0049] It should be noted that the organic phase loaded with rhenium is washed with a detergent to remove the entrained impurity elements and molybdenum.

[0050] In some embodiments, the stripping agent used when performing the stripping comprises one or more of ammonia, sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate and ammonium bicarbonate; The mass concentration of the stripping agent is 1%-25%.

[0051] Optionally, the mass concentration of the stripping agent can be 1%, 5%, 10%, 15%, 20%, 25% or any value between 1%-25%.

[0052] The embodiments of the present application will be described in detail below with specific examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0053] Example 1 The first aspect of the present embodiment provides a substituted imidazole compound, which has the following structural formula: .

[0054] The second aspect of the present embodiment provides a preparation method of a substituted imidazole compound, which specifically comprises: S1: 5.26 g of benzil, 3.02 g of benzaldehyde, 5.33 g of ammonium acetate and 0.54 g of sucrose are stirred in 250 mL of ethanol for 72 h, filtered and washed with ethanol to obtain a white solid, which is 2,4,5-triphenyl imidazole; S2: 14.591 g of 2,4,5-triphenyl imidazole, 12.075 g of iodoctane and 1.44 g of NaH are refluxed in THF for 4 h, filtered, the filtrate is distilled under reduced pressure to remove the solvent, and then purified by PE:EA=4:1 column to obtain 1-octyl-2,4,5-triphenyl imidazole; S3: 5.163 g of 1-octyl-2,4,5-triphenyl imidazole and 1.946 g of dimethyl sulfate are refluxed in 100 mL of acetonitrile for 6 h, the solvent is removed by distillation under reduced pressure, and then purified by dichloromethane:methanol=20:1 silica gel column to obtain the substituted imidazole compound.

[0055] The proton nuclear magnetic resonance spectrum (H-NMR) of the substituted imidazole compound is shown in 1 H-NMR. Figure 1 The obtained product has a clear and single structure, which provides a solid foundation for the stable and reproducible extraction performance in the subsequent extraction.

[0056] The third aspect of the present embodiment provides a rhenium extraction agent, which comprises, based on a total volume of 100%: Substituted imidazole compound 5%, tributyl phosphate 10% and the balance of sulfonated kerosene; The fourth aspect of the embodiment provides a preparation method of the rhenium extractant, and the specific preparation steps are as follows: S4: After the above raw materials are mixed, stirring is performed at room temperature to obtain the rhenium extractant.

[0057] The fifth aspect of the embodiment provides a method for separating molybdenum and rhenium, and the solution to be extracted is a copper smelting waste acid solution, wherein the concentration of rhenium in the copper smelting waste acid solution is 6 mg / L, the concentration of molybdenum is 12 mg / L, and the pH is 0.0; the specific steps are as follows: S5: The rhenium extractant is used to extract the solution to be extracted, and then washing and stripping are performed to obtain a high-purity rhenium salt and a molybdenum-containing solution; the volume ratio of the organic phase to the aqueous phase in the mixture of the rhenium extractant and the solution to be extracted is 1:5; the extraction temperature is 20°C, and the extraction time is 5 min; the washing agent used for washing is 10 g / L sulfuric acid; the stripping agent used for stripping is 10% ammonia water, the stripping temperature is 20°C, the stripping time is 3 min, and the rhenium extractant after stripping is continuously recycled.

[0058] Embodiment 2 The first aspect of the embodiment provides a rhenium extractant, and the raw materials, with a total volume of 100%, include: Substituted imidazole compound 10% (consistent with embodiment 1), oxidized tri-octyl phosphine 30% and the balance of n-hexane.

[0059] The preparation method of the rhenium extractant is consistent with that of embodiment 1.

[0060] The second aspect of the embodiment provides a method for separating molybdenum and rhenium, and the solution to be extracted is an acid leaching solution of molybdenum concentrate, wherein the concentration of rhenium in the acid leaching solution of molybdenum concentrate is 0.07 g / L, the concentration of molybdenum is 4 g / L, and the pH is 1.0; the specific steps are as follows: The rhenium extractant is used to extract the solution to be extracted, and then washing and stripping are performed to obtain a high-purity rhenium salt and a molybdenum-containing solution; the volume ratio of the organic phase to the aqueous phase in the mixture of the rhenium extractant and the solution to be extracted is 1:1; the extraction temperature is 25°C, and the extraction time is 10 min; the washing agent used for washing is 40 g / L sulfuric acid solution; the stripping agent used for stripping is 15wt% ammonium carbonate solution, the stripping temperature is 35°C, the stripping time is 7 min, and the rhenium extractant after stripping is continuously recycled.

[0061] Embodiment 3 The first aspect of the embodiment provides a rhenium extractant, and the raw materials, with a total volume of 100%, include: Substituted imidazole compound 25%, oxidized tri-octyl phosphine 25% and the balance of octanol.

[0062] The preparation method of the rhenium extractant is consistent with that in Example 1.

[0063] The second aspect of the embodiment provides a method for separating molybdenum and rhenium, wherein the to-be-extracted solution is a mixed solution of sodium perrhenate and sodium molybdate, the concentration of rhenium in the mixed solution is 10 g / L, the concentration of molybdenum is 20 g / L, and the pH is 5.0; and the specific steps are as follows: The to-be-extracted solution is extracted by using the rhenium extractant, and then washed and stripped to obtain a high-purity rhenium salt and a molybdenum-containing solution; the volume ratio of the organic phase to the aqueous phase in the mixture of the rhenium extractant and the to-be-extracted solution is 5:1; the extraction temperature is 45°C, and the extraction time is 3 min; the washing agent used for washing is a 30 g / L sulfuric acid solution; the stripping agent used for stripping is a 20 wt% sodium carbonate solution, the stripping temperature is 40°C, the stripping time is 10 min, and the rhenium extractant after stripping is continuously recycled.

[0064] Comparative Example 1 The first aspect of the comparative example provides a rhenium extractant, and the raw materials, based on a total volume of 100%, include: 25% tri-n-octylamine (N235) extractant, 5% tributyl phosphate, and the balance of octanol.

[0065] The preparation method of the rhenium extractant is consistent with that in Example 1.

[0066] The second aspect of the embodiment provides a method for separating molybdenum and rhenium, wherein the to-be-extracted solution is a mixed solution of sodium perrhenate and sodium molybdate, the concentration of rhenium in the mixed solution is 10 g / L, the concentration of molybdenum is 20 g / L, and the pH is 5.0; and the specific steps are as follows: The to-be-extracted solution is extracted by using the rhenium extractant, and then washed and stripped to obtain a high-purity rhenium salt and a molybdenum-containing solution; the volume ratio of the organic phase to the aqueous phase in the mixture of the rhenium extractant and the to-be-extracted solution is 5:1; the extraction temperature is 45°C, and the extraction time is 3 min; the washing agent used for washing is a 30 g / L sulfuric acid solution; the stripping agent used for stripping is a 20 wt% sodium carbonate solution, the stripping temperature is 40°C, the stripping time is 10 min, and the rhenium extractant after stripping is continuously recycled.

[0067] Comparative Example 2 The difference from Example 1 is that the rhenium extractant, based on a total volume of 100%, includes: 10% tributyl phosphate and the balance of sulfonated kerosene; that is, the comparative example does not add a substituted imidazole compound.

[0068] Comparative Example 3 The difference from Example 1 is that the rhenium extractant, based on a total volume of 100%, includes: The sulfonated kerosene replaces 10% of the imidazole compound and the balance is added; that is, no tributyl phosphate is added in this comparative example.

[0069] The extraction rate and purity of sodium perrhenate obtained in the above examples and comparative examples are shown in Table 1.

[0070] Table 1 Extraction rate and purity of sodium perrhenate

[0071] The purity was determined by using an ICP-MS instrument to measure the content of sodium perrhenate and sodium molybdate in the solution, thus obtaining the purity of sodium perrhenate.

[0072] analyze: After extracting a mixed solution of sodium perrhenate and sodium molybdate using the rhenium extractant provided in this application, the extraction rate of sodium perrhenate is ≥90%, reaching a maximum of 99.6%, while the purity of sodium perrhenate is high with few impurities, reaching ≥99%, and a maximum of 99.98%. Compared with Comparative Example 1, the rhenium extractant provided in this application can be used for the extraction of rhenium and can achieve a very good extraction effect.

[0073] The traditional amine extractant N235 described in Comparative Example 1 exhibits poor selectivity. While the extraction rate of rhenium (88.9%) is acceptable, the co-extraction rate of molybdenum is as high as 90.9%, resulting in a final rhenium product purity of only 90.09%, far lower than that of the embodiments in this application. Trioctylamine (N235), as a long-chain tertiary amine, relies primarily on the formation of ion pairs with anions for extraction. Its molecular structure lacks the precise "stereoconfined cavity" of the substituted imidazole compounds in this application, making it unable to distinguish between molybdenum and rhenium. In acidic systems, N235 shows poor selectivity for different anions, not only extracting ReO4 but also... - Furthermore, it can react with various polymerized molybdate ions present in the solution, leading to poor separation of molybdenum and rhenium. Data from this application directly demonstrates that its selectivity is far lower than that of the substituted imidazole compound system of this invention.

[0074] Comparative Example 2, containing only a co-extractant (without substituted imidazole compounds), showed a acceptable rhenium extraction rate (89.6%), but an extremely low molybdenum co-extraction rate (0.23%), and a relatively high purity (99.3%). This comparative example reveals the limitations of using a single co-extractant. Neutral phosphorus-containing extractants such as TBP themselves have limited effect on ReO4. - It exhibits some solvation extraction capability, thus demonstrating a certain rhenium extraction rate and relatively high purity (due to TBP's weak affinity for molybdenum polymer ions). However, its rhenium extraction rate is lower than that of Example 1 (99.6%), proving that the overall rhenium capture capacity and efficiency of the system are insufficient in the absence of a primary extractant. This system is like a "broad but not precise" catcher, able to avoid most impurities, but lacking sufficient capture power for the target analyte.

[0075] Comparative Example 3 contains only the substituted imidazole compound (without a synergist), and the rhenium extraction rate drops to 90.2%, and the molybdenum co-extraction rate is very low (0.10%), and the purity is still acceptable (99.2%). The low molybdenum co-extraction rate proves that the substituted imidazole compound (primary agent) itself has excellent intrinsic selectivity, and its steric and electronic screening mechanism is effective. However, the single primary agent may have the problems of slow extraction kinetics and low saturation capacity. The addition of a synergist, as described above, greatly improves the extraction driving force and efficiency by forming a ternary complex. Without a synergist, the imidazole extractant cannot fully exert its potential.

[0076] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacements for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

[0077] In addition, those skilled in the art can understand that although some embodiments herein include certain features rather than others included in other embodiments, the combination of features of different embodiments means that it is within the scope of the present application and forms different embodiments. For example, any one of the claimed embodiments can be used in any combination. The information disclosed in the BACKGROUND section is only intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A substituted imidazole compound, characterized in that, Its structural formula is: 。 2. A method for preparing the substituted imidazole compound according to claim 1, characterized in that, include: 2,4,5-Triphenylimidazolium was obtained by second mixing, first reaction, solid-liquid separation of phenylethylene glycol, benzaldehyde, ammonium acetate, sucrose and organic solvent; The 2,4,5-triphenylimidazole, iodooctane, NaH and tetrahydrofuran were subjected to a third mixing, a second reaction, vacuum distillation and a first purification to obtain 1-octyl-2,4,5-triphenylimidazole; The substituted imidazole compound was obtained by a fourth mixing, a third reaction, vacuum distillation, and a second purification of the 1-octyl-2,4,5-triphenylimidazole, dimethyl sulfate, and acetonitrile.

3. The method for preparing the substituted imidazole compound according to claim 2, characterized in that, At least one of the following conditions must be met: (1) The mass ratio of the diphenylethylene glycol, the benzaldehyde, the ammonium acetate, and the sucrose is 1-10:1-10:1-10:0-2; (2) The mass ratio of the 2,4,5-triphenylimidazolium, the iodooctane and the NaH is 10-20:10-20:0.5-2.5; (3) The mass ratio of the 1-octyl-2,4,5-triphenylimidazole to the dimethyl sulfate is 1-4:1; (4) The first purification is performed using a first eluent, which comprises petroleum ether and ethyl acetate; the volume ratio of the petroleum ether to the ethyl acetate is 1-5:1-5; (5) The second purification is performed using a second eluent comprising dichloromethane and methanol; the volume ratio of the dichloromethane to the methanol is 1-70:1-10; (6) The temperature of the first reaction is 10-40℃ and the time is 24-72h; (7) The temperature of the second reaction is 40-80℃ and the time is 1-10h; (8) The temperature of the third reaction is 70-100℃ and the time is 2-10h.

4. A rhenium extractant, characterized in that, Its raw materials, calculated by total volume of 100%, include: 5%-40% substituted imidazole compounds, 10%-40% co-extractant, and the balance as diluent; The co-extractant is a neutral phosphorus-containing extractant and / or an acidic phosphorus-containing extractant; The substituted imidazole compound includes the substituted imidazole compound of claim 1 or the substituted imidazole compound prepared by the preparation method of the substituted imidazole compound of claim 2 or 3.

5. The rhenium extractant according to claim 4, characterized in that, At least one of the following conditions must be met: (1) The co-extractant is selected from one or more of tributyl phosphate, trioctyl phosphate and trioctylphosphine oxide; (2) The diluent is selected from one or more of kerosene, sulfonated kerosene, hexane, octane, dichloromethane, dichloroethane, chloroform, octanol, toluene and xylene.

6. A method for preparing the rhenium extractant according to claim 4 or 5, characterized in that, include: The raw materials are first mixed to prepare the product.

7. A method for separating molybdenum and rhenium, characterized in that, include: A fifth mixing of an acidic solution containing molybdenum and rhenium and a rhenium extractant yields a mixture; the mixture is then extracted and back-extracted to obtain a perrhenate solution and a molybdenum-containing solution. The rhenium extractant includes the rhenium extractant of claim 4 or the rhenium extractant prepared by the preparation method of the rhenium extractant of claim 5 or 6.

8. The method for separating molybdenum and rhenium according to claim 7, characterized in that, At least one of the following conditions must be met: (1) The acidic solution containing molybdenum and rhenium includes copper smelting waste acid and / or molybdenum concentrate acid leaching solution; (2) The pH value of the acidic solution containing molybdenum and rhenium is less than 7; (3) The concentration of rhenium in the acidic solution containing molybdenum and rhenium is 0.006-10 g / L and the concentration of molybdenum is 0.012-20 g / L.

9. The method for separating molybdenum and rhenium according to claim 7, characterized in that, At least one of the following conditions must be met: (1) The extraction and back-extraction temperatures are each 20-25℃ and the extraction times are each 5-10 min; (2) The volume ratio of the organic phase to the aqueous phase in the mixture is 1-5:1-5.

10. The method for separating molybdenum and rhenium according to any one of claims 7-9, characterized in that, At least one of the following conditions must be met: (1) Before back-extraction, the organic phase obtained after extraction is washed with a detergent; The detergent includes one or more of sulfuric acid, hydrochloric acid, and nitric acid; The mass concentration of the detergent is 0.001-50 g / L; (2) The back-extraction agent used in the back-extraction includes one or more of ammonia, sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate; The mass concentration of the back-extraction agent is 1%-25%.

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