A complexing agent composition and separation method for silicon isotope separation

Abstract

A complexing agent composition and separation method for silicon isotope separation belong to the field of isotope separation technology. The complexing agent composition for silicon isotope separation comprises at least two different compounds selected from alcohols, ethers, esters, amines, sulfur-containing organic compounds, and chlorine-containing organic compounds as complexing agents. These complexing agents can undergo a reversible coordination reaction with silicon tetrafluoride to form a complex with an asymmetric octahedral structure. The complexing agent of at least two different compounds comprises a first complexing agent providing a first type of coordinating atom and a second complexing agent providing a second type of coordinating atom. The isotope separation factor of the first type of coordinating atom is higher than that of the second type of coordinating atom, and / or, the chemical bond stability of the second type of coordinating atom is higher than that of the first type of coordinating atom. This method achieves comprehensive optimization of separation efficiency, stability, and operational economy through the synergistic effect of different complexing agents.

Description

Technical Field

[0001] This application belongs to the field of isotope separation technology, and particularly relates to a complexing agent composition and separation method for silicon isotope separation. Background Technology

[0002] Silicon 28 ( 28 Si), Silicon 29 ( 29 Si) and silicon 30 ( 30 Silicon (Si) consists of three natural isotopes of silicon. Their core difference lies in the number of neutrons in their atomic nuclei, leading to variations in physical properties, natural abundance, and applications. In nature, the abundance of these three isotopes varies considerably, with the following abundance (atomic percentage): Silicon-28: approximately 92.23% (the most abundant isotope, accounting for the vast majority of natural silicon); Silicon-29: approximately 4.67% (the second most abundant); Silicon-30: approximately 3.10% (the least abundant). This difference in abundance directly determines the average relative atomic mass of "natural silicon" (approximately 28.085)—the result of a weighted average of the mass numbers of the three isotopes based on their abundance. Silicon-28, due to its highest abundance, is the main component of natural silicon and a core raw material in the semiconductor industry.

[0003] Currently, methods for separating silicon isotopes include gas centrifugation, laser methods, and chemical exchange methods. Among these, chemical exchange methods have attracted attention due to their potential high efficiency and relatively low energy consumption. The principle of this method is to achieve separation by utilizing the thermodynamic or kinetic differences between different isotopes in specific chemical reactions. For silicon isotopes, an effective chemical exchange pathway involves a reversible coordination reaction between silicon tetrafluoride (SiF4) and a complexing agent.

[0004] However, existing technologies lack research findings on the characteristics of different complexing agents, thus existing chemical exchange methods typically employ a single complexing agent, which has significant limitations. Firstly, efficiency and stability are difficult to balance: some complexing agents (such as anisole) may have high single-stage separation factors, but their chemical stability or reaction kinetics under operating conditions are not ideal, easily leading to side reactions or system instability. Conversely, some stable complexing agents (such as trimethyl phosphate) may have insufficient separation efficiency. Secondly, the decomposition temperature of complexes formed by single complexing agents is relatively fixed. If the decomposition temperature is too high, it leads to increased energy consumption and complex side reactions during pyrolysis, generating impurities (such as aldehydes, acids, or polymers). These impurities contaminate the recycling system and reduce the abundance upper limit of the final product. If low-temperature decomposition is desired, it is difficult to find a single complexing agent that also achieves high separation efficiency. Due to these problems, separation systems using a single complexing agent often cannot simultaneously achieve high separation efficiency, low energy consumption, and long-term stable operation, limiting the economically feasible preparation of high-abundance silicon-28.

[0005] Therefore, there is an urgent need in the field for an improved complexing agent scheme and separation method that can overcome the above-mentioned shortcomings. Summary of the Invention

[0006] This application aims to at least partially address one of the technical problems in the related art. To this end, the complexing agent composition and separation method for silicon isotope separation provided in this application, through the synergistic effect of different complexing agents, can achieve comprehensive optimization of separation efficiency, stability, and operational economy.

[0007] To achieve the above objectives, in a first aspect, this application provides a complexing agent composition for the separation of silicon isotopes, the complexing agent composition comprising at least two different compounds selected from alcohols, ethers, esters, amines, sulfur-containing organic compounds and chlorine-containing organic compounds as complexing agents, the complexing agents being capable of undergoing a reversible coordination reaction with silicon tetrafluoride to form a complex with an asymmetric octahedral structure;

[0008] The at least two different compounds include a first complexing agent that provides a first type of coordinating atom and a second complexing agent that provides a second type of coordinating atom.

[0009] Preferably, the isotope separation factor of the first type of coordinating atoms is higher than that of the second type of coordinating atoms, and / or, the chemical bond stability of the second type of coordinating atoms is higher than that of the first type of coordinating atoms.

[0010] Preferably, the isotope separation factor of the first type of coordinating atoms is higher than that of the second type of coordinating atoms, and the chemical bond stability of the second type of coordinating atoms is higher than that of the first type of coordinating atoms.

[0011] Preferably, the first complexing agent is a fatty ether or an aromatic ether, and the second complexing agent is an inorganic acid ester. The fatty ether includes diethyl ether, diisopropyl ether, and methyl tert-butyl ether, the aromatic ether includes phenethyl ether, anisole, and diphenyl ether, and the inorganic acid ester includes phosphate ester, borate ester, and carbonate ester.

[0012] Preferably, the mass ratio of the first complexing agent to the second complexing agent is 70:30 to 40:60.

[0013] Preferably, the first complexing agent is an aliphatic ether or an aromatic ether, and the second complexing agent is a C1-C7 monohydric alcohol.

[0014] Preferably, by mass percentage, the first complexing agent accounts for 60% to 80%, and the second complexing agent accounts for 20% to 40%.

[0015] Preferably, the first and second complexing agents are at least two of phosphate esters, borate esters and carbonates.

[0016] Preferably, the first complexing agent is an ether or ester complexing agent that provides oxygen coordination, and the second complexing agent is an amine complexing agent that provides nitrogen coordination, wherein the amine complexing agent includes at least one of butylamine or dibutylamine.

[0017] Preferably, the first type of coordinating atom is different from the second type of coordinating atom, and is selected from two of oxygen, nitrogen, sulfur, and chlorine.

[0018] Secondly, this application provides a method for the chemical exchange separation of silicon isotopes, which involves using the complexing agent composition described in any of the above claims to perform a reversible complexation reaction with naturally abundant silicon tetrafluoride gas to separate silicon tetrafluoride-28, silicon tetrafluoride-29 and silicon tetrafluoride-30 isotopes.

[0019] Based on the above technical solution, it can be seen that the electronic specialty gas preparation method of this application has at least one of the following beneficial effects compared with the prior art:

[0020] 1. The complexing agent composition provided in this application combines at least two complexing agents selected from different chemical categories (alcohols, ethers, esters, amines, chlorine-containing or sulfur-containing organic compounds) to form a complex with an asymmetric octahedral structure. The asymmetric structure breaks the equilibrium of the thermodynamic stability of the complex, significantly reducing its thermal decomposition temperature. This allows for efficient decomposition at a lower temperature in subsequent pyrolysis processes, greatly reducing energy consumption and effectively suppressing side reactions caused by high temperatures.

[0021] 2. The complexing agent composition provided in this application achieves "maximizing strengths and minimizing weaknesses" by combining a complexing agent with a high separation factor and a complexing agent with high stability. For example, the combination of anisole and phosphate ester maintains a high separation factor while utilizing the stable properties of phosphate ester to suppress possible side reactions of anisole during high-temperature pyrolysis, enabling the system to operate continuously under better conditions.

[0022] 3. The silicon isotope chemical exchange separation method provided in this application utilizes at least two complexing agents in combination to form a complex with an asymmetric octahedral structure. Different complexing agents differ in molecular structure, electronic effects, or steric hindrance, and their combination produces a synergistic effect, resulting in a final composition that outperforms any single component in one or more key properties such as separation factor, reaction rate, thermal stability, or chemical stability. Simultaneously, this asymmetry affects different silicon isotopes (…). 28 Si、 29 Si、 30 The difference in bonding between Si and coordinating atoms enhances the isotope effect, improves separation selectivity, and achieves more efficient silicon isotope separation. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the reaction process of a silicon isotope chemical exchange separation method provided in this application. Detailed Implementation

[0025] To facilitate understanding of this application, a more complete description will be provided below. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] The terms "and / or," "or / and," and "and / or" as used in this application encompass any one of two or more related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and "a combination of A and B."

[0028] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0029] The terms “combinations thereof,” “any combination thereof,” and “any combination thereof” as used in this application include all suitable combinations of any two or more of the listed items.

[0030] In this application, the term "suitable" as used in "suitable combination", "suitable method", "any suitable method", etc., refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0031] In this application, terms such as "preferred," "better," "more suitable," and "ideal" are merely used to describe implementation methods or embodiments that achieve better results, and should be understood not to limit the scope of protection of this application.

[0032] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0033] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0034] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.

[0035] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0036] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0037] In this application, "normal temperature" in the context generally refers to 5℃~30℃, and more preferably 25±5℃.

[0038] In this application, "atmospheric pressure" in the context generally refers to one standard atmosphere, preferably 100±10 kPa.

[0039] This application provides a complexing agent composition for silicon isotope separation. The complexing agent composition contains at least two different compounds selected from alcohols, ethers, esters, amines, sulfur-containing organic compounds, and chlorine-containing organic compounds as complexing agents. The complexing agents can undergo a reversible coordination reaction with silicon tetrafluoride to form a complex with an asymmetric octahedral structure.

[0040] The at least two different compounds include a first complexing agent that provides a first type of coordinating atom and a second complexing agent that provides a second type of coordinating atom.

[0041] This embodiment combines at least two complexing agents selected from different chemical categories (alcohols, ethers, esters, amines, chlorinated or sulfur-containing organics), breaking the performance limitations of single complexing agents and laying the foundation for synergistic effects. Different complexing agents differ in molecular structure, electronic effects, and steric hindrance; their combination produces a synergistic effect, forming an asymmetric octahedral complex. This disrupts the thermodynamic equilibrium of the symmetric complex, weakens the overall bond energy of the central Si-F coordination bond, significantly reduces the thermal decomposition temperature of the complex, and achieves complete decomposition at low temperatures, fundamentally suppressing high-temperature polymerization and oxidation side reactions. The resulting composition outperforms any single component or simple addition in one or more key properties such as separation factor, reaction rate, thermal stability, or chemical stability, providing a novel material basis for achieving more efficient silicon isotope separation.

[0042] In some embodiments, the isotope separation factor of the first type of coordinating atoms is higher than that of the second type of coordinating atoms, and / or, the chemical bond stability of the second type of coordinating atoms is higher than that of the first type of coordinating atoms.

[0043] This embodiment explicitly requires that the complexing agents in the combination have differentiated advantages in key performance aspects (either a high separation factor or good stability). This design allows the composition to simultaneously achieve high separation efficiency and long-term operational stability. During the separation process, the high separation factor component ensures excellent isotope enrichment ability and guarantees the single-stage separation coefficient, while the high stability component can suppress side reactions within the system, reduce complexing agent degradation and impurity generation, thereby effectively solving the technical contradiction that a single complexing agent cannot simultaneously achieve "efficiency" and "stability".

[0044] In some embodiments, the isotope separation factor of the first type of coordinating atoms is higher than that of the second type of coordinating atoms, and the chemical bond stability of the second type of coordinating atoms is higher than that of the first type of coordinating atoms.

[0045] This embodiment is a preferred embodiment of the above embodiments, explicitly requiring that the complexing agent composition simultaneously contains different complexing agents with both high separation factor and high stability. This represents the most ideal synergistic design, enabling the complexing agent composition to significantly improve the chemical and thermodynamic stability of the system without sacrificing separation efficiency. The resulting unexpected technical effects include: extended complexing agent cycle life, reduced material loss and impurity accumulation due to side reactions, and increased abundance upper limit of the final product, thereby significantly reducing overall separation costs.

[0046] In some embodiments, the first complexing agent is a fatty ether or an aromatic ether, and the second complexing agent is an inorganic acid ester. The fatty ether includes diethyl ether, diisopropyl ether, and methyl tert-butyl ether, the aromatic ether includes phenethyl ether, anisole, and diphenyl ether, and the inorganic acid ester includes phosphate ester, borate ester, and carbonate ester.

[0047] This embodiment provides a highly efficient and stable preferred combination example: specifically defined as aliphatic / aromatic ethers (first complexing agent) and inorganic acid esters (second complexing agent). Ethers (especially aromatic ethers such as anisole) typically have high separation factors, while inorganic acid esters (such as trimethyl phosphate) are known for their excellent thermal stability and chemical inertness. This combination fully leverages the high separation efficiency of ethers while utilizing the "protective" effect of inorganic acid esters, greatly enhancing the overall reaction system's long-term performance, especially its tolerance at high pyrolysis temperatures, making it a reliable solution for achieving stable and efficient separation. Furthermore, the mass ratio of the first and second complexing agents is 70:30 to 40:60. By limiting the mass ratio range of ethers to inorganic acid esters (70:30 to 40:60), the specific ratio for achieving the optimal synergistic effect is clearly defined. Within this window, sufficient ether components are ensured to maintain a high separation factor, while adequate inorganic acid esters provide sufficient stability. This preferred range is an experimentally verified equilibrium point; exceeding this range may lead to a significant decrease in separation efficiency or insufficient improvement in stability.

[0048] In some embodiments, the first complexing agent is an aliphatic ether or an aromatic ether, and the second complexing agent is a C1-C7 monohydric alcohol.

[0049] Optimizing reaction kinetics and mass transfer processes: This embodiment combines complexing agents with high-separation-factor ethers and low-molecular-weight alcohols (C1-C7 single alcohols). The addition of small-molecule alcohols effectively reduces the viscosity of the complexing liquid system, improving its flowability and diffusion properties. This helps form a thinner, more uniform liquid film in the complexing column, thereby significantly increasing the mass transfer rate and tray efficiency between the gas and liquid phases. While maintaining high separation selectivity, it increases the processing capacity per unit time or allows for the use of smaller equipment.

[0050] Ethers (providing oxygen): As the primary complexing agent, their molecular structure and electronic effects exhibit high recognition ability for silicon isotopes, resulting in a high separation factor. Low-carbon alcohols (providing oxygen): As co-complexing agents, their small molecular size and rapid diffusion enhance the overall reaction rate, overcoming potential kinetic bottlenecks associated with single ethers. Simultaneously, alcohols can regulate the polarity of the entire mixture, optimizing the reaction environment. This combination achieves a high theoretical separation efficiency. Furthermore, by mass percentage, the first complexing agent comprises 60%–80%, and the second complexing agent comprises 20%–40%. This provides an optimal concentration range for the ether-alcohol (low-carbon number) combination, ensuring that while the alcohol effectively reduces viscosity and improves mass transfer, it does not excessively dilute the ether component, which is the primary separation agent, thus maintaining a high overall separation factor.

[0051] In some embodiments, the first and second complexing agents are at least two of phosphate esters, borate esters, and carbonates.

[0052] This embodiment provides a combination of two or more inorganic acid esters (such as phosphate esters and borate esters). The outstanding advantage of such combinations lies in their excellent chemical and thermal stability. They offer maximum resistance to side reactions such as decomposition and oxidation, introduce virtually no impurities from their own degradation, and are particularly suitable for long-term continuous production processes with extremely high requirements for system cleanliness and operational stability, thus facilitating the production of high-purity products with extremely low impurity content.

[0053] Preferably, a complexing agent composition of trimethyl phosphate and trimethyl borate can be used. Trimethyl phosphate (providing oxygen): Containing phosphate ions in its molecule, it has a stable structure and a high thermal decomposition temperature, significantly improving the stability of the entire complexing liquid system. Trimethyl borate (providing oxygen): Also possesses good stability, and its molecular structure is compatible with the silicon system. The combination of the two can form a "stabilizer" effect, effectively suppressing byproducts generated due to the decomposition of the complexing agent under the high-temperature environment of the cracking tower. Expected results: Stable system operation, low complexing agent loss, and low impurity generation, helping to increase the upper limit of the abundance of the final product, but the separation factor may be slightly lower than that of the combination of ethers and inorganic acid esters.

[0054] In some embodiments, the first complexing agent is an ether or ester complexing agent that provides oxygen coordination, and the second complexing agent is an amine complexing agent that provides nitrogen coordination, wherein the amine complexing agent includes at least one of butylamine or dibutylamine.

[0055] In this embodiment, an octahedral complex with an asymmetric coordination environment is created by combining ethers / esters that provide oxygen coordination with amines that provide nitrogen coordination. This asymmetry weakens the overall stability of the complex, resulting in a significant reduction in its thermal decomposition temperature. The direct benefits of lowering the decomposition temperature are: a substantial reduction in high-temperature-induced side reactions, savings in heating energy consumption, and potentially increased decomposition rate of the complex, thereby improving the overall economics and product yield of the process.

[0056] In some embodiments, the first type of coordinating atoms differs from the second type of coordinating atoms and is selected from two of oxygen, nitrogen, sulfur, and chlorine. The sulfur atom originates from sulfur-containing complexing agents such as thioethers and thiols, while the chlorine atom may originate from chlorobenzene, chloroform, or 1,2-dichloroethane.

[0057] In this embodiment, by explicitly introducing different types of coordinating atoms (O, N, S, Cl) to expand the scope of coordination chemistry regulation, the means of regulating the properties of complexes are greatly enriched. Different coordinating atoms have different electronegativity, coordination ability, and spatial requirements. By combining them, the electron cloud density, geometry, and bonding strength of the central silicon atom in the complex can be finely tuned, thereby providing a broader molecular design space for achieving specific separation factors, reactivity, or decomposition temperature targets.

[0058] like Figure 1 As shown, in some embodiments, a silicon isotope chemical exchange separation method is provided, applied to a silicon isotope chemical exchange system. The silicon isotope chemical exchange system is arranged from left to right as a complexing tower, multiple exchange towers, a cracking tower, and a purification tower; wherein the number of multiple exchange towers is preferably three or more. The system also includes a feed tower, into which naturally abundant silicon tetrafluoride gas and the aforementioned complexing agent composition that can undergo a reversible chemical reaction are fed together for mixing and a preliminary complexing reaction. When the molar ratio of complexing agent to silicon tetrafluoride in the reaction mixture of the feed tower reaches between 1.5 and 3.0, the circulating pump of the feed tower is turned off, and the reaction mixture is pumped into the feed inlet of the middle exchange tower among the multiple exchange towers, entering the circulation system.

[0059] The silicon isotope chemical exchange separation method in this embodiment includes:

[0060] S1. The reaction mixture in the feed tower is fed into the feed inlet of the middle exchange tower among multiple exchange towers. The exchange tower has a condensation jacket. By controlling the flow rate of the condensate, the temperature inside the exchange tower is kept within a certain range. Complexes are generated in the exchange tower and pass through multiple exchange towers in sequence before entering the cracking tower.

[0061] Among them, the number of series-connected exchange towers is greater than or equal to 3, which can increase the total separation factor of a single stage;

[0062] S2. The complex is decomposed by heating in the cracking tower. The complexing agent mixture is obtained at the bottom outlet of the cracking tower and flows into the impurity removal tower. The impurity-removed complexing agent is collected at the top outlet of the impurity removal tower and flows into the top circulation port of the complexing tower. Silicon tetrafluoride gas is obtained at the top outlet of the cracking tower. After passing through the gas buffer tank, it enters the bottom circulation port of the exchange tower located at the end. Then, it passes through multiple exchange towers from back to front and returns to the bottom circulation port of the complexing tower. It undergoes a complexation reaction with the purified complexing agent in the complexing tower to obtain the complexed product.

[0063] S3. Once all parameters in the system have stabilized and the silicon isotope abundance in the complexation products reaches the target abundance, silicon-29 and silicon-30 isotope products are extracted from the bottom of the leftmost complexation tower, and silicon tetrafluoride-28 isotope gas with the target abundance is extracted from the top of the cracking tower. High-boiling-point impurities and residual liquid at the bottom of the impurity removal tower are discharged for waste liquid treatment.

[0064] The silicon-28 abundance in the silicon tetrafluoride-28 isotope gas prepared by this method can reach over 99.999%.

[0065] Preferably, the reaction conditions for the isotope coordination exchange reaction in the multi-stage exchange tower are: a wide operating pressure of 0.1 MPa to 1 MPa and a wide operating temperature of 5°C to 50°C; for industrial applications, the preferred operating temperature of the exchange tower is 10 to 30°C and the operating pressure is 0.2 to 0.6 MPa.

[0066] The temperature of the feed tower is 0~100℃ and the pressure inside the tower is 50~300kPa; the operating temperature of the pyrolysis tower is 150~300℃.

[0067] Preferably, the temperature of the feed tower is 15~35℃ and the pressure inside the tower is 90~150kPa; the operating temperature of the pyrolysis tower is 190~210℃.

[0068] When the tower body temperature of the feed tower is below 15℃, the viscosity of the system increases significantly, the fluidity of the complexing agent deteriorates, the dissolution and diffusion rate of SiF4 gas in the liquid phase decreases, the kinetics of the complexation reaction slows down, the feed cycle is greatly extended, and the production efficiency is reduced. At low temperatures, the solubility of some esters and ethers decreases, making them prone to stratification, which disrupts the homogeneity of the multi-component complex system and makes it impossible to stably form asymmetric octahedral complexes.

[0069] When the temperature of the feed tower exceeds 35℃, the solubility of SiF4 gas decreases rapidly, gas phase loss increases, and raw material utilization rate decreases. At the same time, the volatility of ether and amine components increases, the complexing agent is lost with the gas phase during the pre-complexation stage, and the ratio is unbalanced. High temperature will prematurely trigger weak oxidation side reactions, and trace amounts of aldehydes and organic acid impurities will be generated in advance, polluting the circulation system.

[0070] The temperature of the feed tower is in the range of 15~35℃, which can take into account the liquid phase fluidity, SiF4 solubility, and thermal stability of the complexing agent. All binary, ternary and multi-component complexing agents can maintain a homogeneous liquid phase. The reversible coordination reaction rate is moderate, the feed time is shortened, there is almost no loss of complexing agent volatilization, no early side reaction is generated, and the concentration of the asymmetric complex generated by pre-complexation is stable and controllable.

[0071] The pressure inside the feed tower is below 90 kPa, close to atmospheric pressure. The saturated solubility of SiF4 is low, and the gas-liquid contact time needs to be significantly increased to achieve the feed endpoint with a molar ratio of 1.5 to 3.0.

[0072] The pressure inside the feed tower is higher than 150 kPa, which increases the requirements for the system's airtight pressure resistance and significantly increases the manufacturing costs of equipment walls, valves, and pipelines.

[0073] The pressure inside the feed tower is in the range of 90~150kPa, which is a slightly positive pressure and mild operating condition. Ordinary normal pressure tower equipment can be adapted with minor modifications, resulting in low equipment investment. The SiF4 dissolution is sufficient to quickly reach the target complex molar ratio. The gas-liquid balance is adapted to the isotope exchange requirements, fully preserving the high separation factor of the multi-component complex system, while avoiding high pressure safety risks, and taking into account production capacity, equipment cost and operational stability.

[0074] The pyrolysis temperature in the pyrolysis tower is below 190℃, resulting in incomplete decomposition of the asymmetric octahedral complexes formed by the multi-component compound. A large amount of unpyrolyzed silicon complexes remain at the bottom of the vessel, and these residual complexes are enriched within the vessel. 29 Si、 30 The discharge of silicon isotopes with waste liquid significantly reduces the overall recovery rate of silicon isotopes.

[0075] The pyrolysis temperature of the pyrolysis tower exceeds 210℃: the overall heat load of the system increases significantly, the energy consumption of heating steam and heat transfer oil increases significantly, and the production and operating costs rise; under high temperature conditions, ethers, amines, and alcohol complexing agents undergo violent oxidation, polymerization, and chain scission side reactions, generating a large amount of high-boiling-point organic impurities; in particular, sulfur- and chlorine-containing additives in ternary and multi-component compound systems are prone to decomposition at high temperatures, producing corrosive acidic substances that corrode the metal materials of the tower bottom and heat exchangers, significantly shortening the service life of the equipment; the continuous accumulation of impurities will continuously reduce 28 The upper limit of Si isotope abundance requires frequent shutdowns for impurity removal and cleaning.

[0076] The optimal pyrolysis temperature for the pyrolysis tower is 190~210℃. Within this range, the asymmetric octahedral complex formed by the binary / ternary multi-component compound of this invention can achieve more than 99% complete pyrolysis, with the bottom decomposition residue rate as low as less than 0.3%, and almost no loss of isotopic materials. Compared with high-temperature pyrolysis above 220℃, the overall heating energy consumption is reduced by 20%~35%, resulting in significant energy-saving benefits for long-term large-scale production. Furthermore, the impurity generation rate is extremely low, the slag discharge cycle of the impurity removal tower is extended by 3~5 times, and the device can operate continuously and stably for more than 72 hours without shutdown for cleaning, greatly improving the efficiency of industrial production.

[0077] The following are specific embodiments. They are intended to provide a more detailed description of this application to help those skilled in the art and researchers better understand it. The technical conditions described do not constitute any limitation on this application. Any modifications made within the scope of the claims of this application are protected by the claims.

[0078] Unless otherwise stated, all raw materials and reagents used in the following examples are commercially available or can be prepared by known methods. Experimental methods not specifying particular conditions in the examples were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0079] In some embodiments, the silicon isotope chemical exchange separation method includes:

[0080] (1) The reaction mixture in the feed tower is fed into the feed inlet of the middle exchange tower among multiple exchange towers, where a complex is generated. The complex passes through multiple exchange towers in sequence and then enters the cracking tower.

[0081] (2) The complex is decomposed by heating in the cracking tower. The working temperature of the cracking tower is 150~300℃.

[0082] (3) When all parameters in the system reach a stable state and the silicon isotope abundance in the complexation product reaches the target abundance, silicon-29 and silicon-30 isotope products are collected from the bottom of the leftmost complexation tower, and silicon tetrafluoride-28 isotope gas with the target abundance is collected from the top of the cracking tower.

[0083] Example 1

[0084] The complexing agent composition uses anisole (first complexing agent) and trimethyl phosphate (second complexing agent), both of which provide oxygen coordination, and the mass ratio of anisole to trimethyl phosphate is 70:30.

[0085] Process conditions: pyrolysis tower temperature 172℃;

[0086] Test results: decomposition residue rate 0.3%, complexing agent loss rate 0.8%, single-stage separation factor 1.022.

[0087] Example 2

[0088] The complexing agent composition uses anisole and n-butanol, both of which provide oxygen coordination, with a mass ratio of anisole to butanol of 85:15.

[0089] Process features: n-Butanol reduces liquid phase viscosity and improves gas-liquid mass transfer efficiency;

[0090] Test results: pyrolysis temperature 138℃, decomposition residue rate 0.5%, complexing agent loss rate 2.2%, single-stage separation factor 1.029 (highest separation factor among all examples).

[0091] Example 3

[0092] The complexing agent composition uses trimethyl phosphate and trimethyl borate, both of which provide oxygen coordination, and the mass ratio of trimethyl phosphate to trimethyl borate is 50:50.

[0093] Advantages: Optimal system stability and minimal impurity formation;

[0094] Test results: pyrolysis temperature 125℃, decomposition residue rate 0.7%, complexing agent loss rate 1.1%, single-stage separation factor 1.025.

[0095] Example 4

[0096] The complexing agent composition uses anisole and butylamine, which provide oxygen coordination and nitrogen coordination, respectively, with a mass ratio of anisole to butylamine of 90:10.

[0097] Advantages: Heterocoordination significantly reduces pyrolysis temperature and results in significant energy savings;

[0098] Test results: pyrolysis temperature 118℃, decomposition residue rate 0.9%, complexing agent loss rate 1.8%, single-stage separation factor 1.023.

[0099] Example 5

[0100] The complexing agent composition uses diethyl sulfide and pentanol to provide sulfur coordination and oxygen coordination, respectively, with a mass ratio of diethyl sulfide to pentanol of 80:20.

[0101] Test results: pyrolysis temperature 144℃, decomposition residue rate 0.8%, complexing agent loss rate 1.5%, single-stage separation factor 1.025.

[0102] Example 6

[0103] The complexing agent composition uses pentanol and chloroform, which provide oxygen coordination and chlorocoagulation respectively, with a mass ratio of pentanol to chloroform of 95:5.

[0104] Advantages: Lowest pyrolysis temperature across the entire series, with optimal energy consumption;

[0105] Test results: pyrolysis temperature 105℃, decomposition residue rate 1.1%, complexing agent loss rate 1.7%, single-stage separation factor 1.027.

[0106] The comparative example used a single complexing agent, n-pentanol;

[0107] Test results: pyrolysis temperature 150℃, decomposition residue rate 1.8%, complexing agent loss rate 4.5%, single-stage separation factor 1.022.

[0108] In the same small-scale complexation-pyrolysis experimental apparatus, using naturally abundant SiF4 as raw material, and controlling the same key operating parameters such as complexation temperature, pressure, and gas-liquid ratio, after the operation stabilized, data were collected and analyzed, and the performance summary results are shown in Table 1.

[0109] Table 1 Comparison of key performance parameters between each embodiment and the comparative example.

[0110] Experimental results show that, compared with the comparative example (single n-pentanol), the complexing agent composition of this application exhibits significant and unexpected improvements in several key performance aspects. For example, Example 1 reduced the complexing agent loss rate by more than 77% while maintaining high pyrolysis efficiency; Example 4 further reduced the pyrolysis temperature by 32°C and controlled the complex decomposition residue rate to below 0.3% through heteroatomic coordination design, thereby greatly improving the recovery rate and upper limit of product purity of silicon-28 isotope while saving energy. These synergistic effects and breakthrough results cannot be achieved by a single complexing agent or a simple mixture.

[0111] It should be noted that the complexing agent composition of the present invention is not limited to a two-component mixture. Technical solutions that include three or more different types of complexing agents in combination are all within the complete protection scope of this invention. The multi-component compound system can simultaneously possess multiple advantages such as high separation coefficient, high thermal stability, low liquid phase viscosity, and low-temperature pyrolysis, achieving comprehensive performance that cannot be achieved by single / two-component systems through multi-component synergy.

[0112] A typical example of a ternary compound: anisole (aromatic ether, high separation factor) + trimethyl phosphate (phosphate ester, high thermal stability) + n-butanol (C1~C7 monohydric alcohol, viscosity reduction and mass transfer aid); this ternary system simultaneously solves multiple problems associated with single ethers, such as easy decomposition at high temperatures, low separation efficiency of single esters, high liquid-phase viscosity in ether-ester binary systems, and poor gas-liquid mass transfer. Furthermore, more ternary and quaternary compound combinations can be developed.

[0113] Anisole + Trimethyl phosphate + Dibutylamine (ether + ester + amine, O + O + N tricoordinate atoms);

[0114] Methyl tert-butyl ether + trimethyl borate + chloroform (fatty ether + borate ester + chlorinated organic compound, O + O + Cl);

[0115] Diethyl sulfide + n-pentanol + dimethyl carbonate (sulfide + monohydric alcohol + carbonate, S+O+O). Any reasonable combination of the above three or more complexing agents, as long as the raw materials are selected from alcohols, ethers, esters, amines, or chlorinated organic compounds, and can form an asymmetric octahedral reversible complex with SiF4, falls within the scope of protection of this invention. The mass ratio of each component in the multi-component compound can be flexibly adjusted according to the working conditions, without strictly limiting the binary ratio range. It is only necessary to ensure that the high separation factor component and the high stability component are the main components of the system, with the remaining complexing agents added as auxiliary additives.

[0116] After all binary and ternary embodiments have been running stably and continuously for 72 hours (using the optimized process temperature and pressure), the top of the pyrolysis tower is collected. 28 The abundance of SiF4 is ≥99.999%, and the content of impurity metal ions and organic decomposition products is less than 1 ppb, which meets the standards for electronic-grade special gases. If it deviates from the preferred range, the abundance, material loss, operating cycle and other indicators will deteriorate to varying degrees.

[0117] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0118] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A complexing agent composition for silicon isotope separation, characterized in that, The complexing agent composition comprises at least two different compounds selected from alcohols, ethers, esters, amines, sulfur-containing organic compounds and chlorine-containing organic compounds as complexing agents, and the complexing agents are capable of undergoing a reversible coordination reaction with silicon tetrafluoride to form a complex with an asymmetric octahedral structure. The at least two different compounds include a first complexing agent that provides a first type of coordinating atom and a second complexing agent that provides a second type of coordinating atom.

2. The complexing agent composition according to claim 1, characterized in that, The isotope separation factor of the first type of coordinating atom is higher than that of the second type of coordinating atom, and / or the chemical bond stability of the second type of coordinating atom is higher than that of the first type of coordinating atom.

3. The complexing agent composition according to claim 1, characterized in that, The isotope separation factor of the first type of coordinating atoms is higher than that of the second type of coordinating atoms, and the chemical bond stability of the second type of coordinating atoms is higher than that of the first type of coordinating atoms.

4. The complexing agent composition according to claim 3, characterized in that, The first complexing agent is a fatty ether or an aromatic ether, and the second complexing agent is an inorganic acid ester. The fatty ether includes diethyl ether, diisopropyl ether, and methyl tert-butyl ether, the aromatic ether includes phenethyl ether, anisole, and diphenyl ether, and the inorganic acid ester includes phosphate ester, borate ester, and carbonate ester.

5. The complexing agent composition according to claim 4, characterized in that, The mass ratio of the first complexing agent to the second complexing agent is 70:30 to 40:

60.

6. The complexing agent composition according to claim 3, characterized in that, The first complexing agent is an aliphatic ether or an aromatic ether, and the second complexing agent is a C1-C7 monohydric alcohol.

7. The complexing agent composition according to claim 4, characterized in that, By mass percentage, the first complexing agent accounts for 60% to 80%, and the second complexing agent accounts for 20% to 40%.

8. The complexing agent composition according to claim 1, characterized in that, The first and second complexing agents are at least two of phosphate esters, borate esters and carbonates.

9. The complexing agent composition according to claim 1, characterized in that, The first complexing agent is an ether or ester complexing agent that provides oxygen coordination, and the second complexing agent is an amine complexing agent that provides nitrogen coordination, wherein the amine complexing agent includes at least one of butylamine or dibutylamine.

10. The complexing agent composition according to claim 1, characterized in that, The first type of coordinating atom is different from the second type of coordinating atom and is selected from two of oxygen, nitrogen, sulfur and chlorine.

11. A method for chemical exchange separation of silicon isotopes, characterized in that, The complexing agent composition according to any one of claims 1-10 is used to undergo a reversible complexation reaction with naturally abundant silicon tetrafluoride gas to separate silicon tetrafluoride-28 isotope, silicon tetrafluoride-29 isotope and silicon tetrafluoride-30 isotope.

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