Preparation system and method of ultra-high purity titanium tetrachloride

Abstract

The application provides a preparation system and method of ultrahigh-purity titanium tetrachloride. The system comprises a two-stage liquid-phase adsorption device, a rectification unit and a precision filtration unit. The two-stage liquid-phase adsorption device comprises a first adsorption column and a second adsorption column arranged in series. The first adsorption column is provided with a first gas inlet, and the second adsorption column is provided with an adsorption product outlet. The first adsorption column is selected from an activated carbon adsorption column, a modified activated carbon adsorption column, a molecular sieve adsorption column or a zeolite adsorption column, and the second adsorption column is a macroporous adsorption resin adsorption column. The rectification unit is provided with a rectification inlet and a rectification gas outlet. The rectification inlet is communicated with the adsorption product outlet through an adsorption product conveying pipeline. The precision filtration unit is provided with a rectification gas inlet and an ultrahigh-purity titanium tetrachloride outlet. The rectification gas inlet is communicated with the rectification gas inlet. The preparation system is used to prepare ultrahigh-purity titanium tetrachloride. The process is simple, the process cost is reduced, and the product quality is improved.

Description

Technical Field

[0001] This invention relates to the field of preparation of ultra-high purity titanium tetrachloride, and more specifically, to a preparation system and method for ultra-high purity titanium tetrachloride. Background Technology

[0002] Ultra-high purity titanium tetrachloride can be used in the production and manufacturing of semiconductor integrated memory devices, serving as a liquid-phase titanium source material for titanium nitride, titanium dioxide, and titanium metal chemical vapor deposition (CVD). It is also used as an electrode material for capacitors in semiconductor memory manufacturing.

[0003] The purity requirements for ultra-high purity titanium tetrachloride used in semiconductors are quite stringent, with a composition requirement of ≥99.99% and all impurities needing to be less than 1 ppb. Impurities, especially metal ion impurities (Sb, As, Cu, Al, Pb, Fe, V, Sn, Ni, etc.), can reduce the insulation performance of the thin film layer deposited in semiconductor devices, leading to circuit board failure due to short circuits. Organic matter and particles in the impurities can also affect the uniformity and smoothness of the deposited film. Typical industrial-grade titanium tetrachloride has a composition of 98%–99%, containing a significant amount of ionic impurities (Si, Sb, As, Cu, Al, Pb, Fe, V, Sn, Ni, etc.), as well as organic matter and particles such as CCl4, CCl3COCl, COCl2, and CS2. Therefore, developing a preparation process for ultra-high purity titanium tetrachloride is of positive significance for the domestic production of electronic specialty gases for semiconductors.

[0004] Currently, the main preparation processes used by domestic and foreign companies are adsorption-filtration and a combination of sub-boiling distillation-rectification-filtration. An existing patent application (JP2007223877A) discloses a method for preparing high-purity titanium tetrachloride using adsorption-filtration: activated carbon with a calcination residue of less than 0.01 wt% and a metal impurity content of less than 30 μg / g is packed into a 316L adsorption column made of glass, PTFE, PFA, or electrolytically polished material under an inert gas environment. Titanium tetrachloride with a total metal impurity content of less than 1000 ppb and a silicon content of less than 500 ppb is adsorbed through a liquid phase with a flow rate of 0.5 / hr to 2 / hr ( / hr i.e., the feed volume per hour is equal to the activated carbon packing volume) or a gas phase with a flow rate of 50 / hr to 200 / hr. If static adsorption is performed, the mass ratio of activated carbon to titanium tetrachloride is 5 wt% to 35 wt%, and the adsorption is allowed to stand for 24 hours. After adsorption, the material is filtered with an accuracy of 0.05 μm. The metallic impurities in titanium tetrachloride are all less than 20 ppb, and the silicon content is below 50 ppb. The drawback of this process is that while activated carbon adsorption can effectively reduce the metal ion and organic matter content in titanium tetrachloride, the limited cleanliness and adsorption capacity of activated carbon itself result in insufficient improvement in product quality and no improvement in the composition.

[0005] Existing patent application (CN108178185A) discloses a method combining sub-boiling distillation, rectification, and filtration: Titanium tetrachloride is thoroughly mixed with a vanadium removal agent in a vanadium removal device, then gently stirred and heated under reflux for 2-3 hours. After cooling, it is filtered through a microporous filter with pores smaller than 0.1 μm, passed through 3-5 sets of sub-boiling distillation units in series, and then purified by two sets of rectification columns in series to obtain a qualified product. The product is filtered and packaged in a local Class 100 cleanroom environment. All equipment is made of high-purity quartz glass, and the rectification columns can be packed columns or tray columns. The product tanks are made of high-purity quartz or stainless steel lined with corrosion-resistant materials. After purification using this method, the product has w(TiCl4) ≥ 99.99999%, the total content of metallic impurities is less than 100 ppb, and the content of any single impurity does not exceed 2 ppb. Although the combined sub-boiling distillation-rectification-filtration process significantly improves the quality of titanium tetrachloride, the process is relatively complex, the sub-boiling distillation has poor continuity, and the production cost is high, making it difficult to scale up production.

[0006] In view of the above problems, there is a need to provide a preparation system for ultra-high purity titanium tetrachloride that simultaneously satisfies the requirements of simple preparation process, low impurity content and low cost. Summary of the Invention

[0007] The main objective of this invention is to provide a preparation system and method for ultra-high purity titanium tetrachloride, so as to solve the problem that the existing ultra-high purity titanium tetrachloride preparation process cannot simultaneously meet the requirements of simple preparation process, low impurity content and low cost.

[0008] To achieve the above objectives, the present invention provides a system for preparing ultra-high purity titanium tetrachloride. This system includes: a two-stage liquid-phase adsorption device, a distillation unit, and a precision filtration unit. The two-stage liquid-phase adsorption device includes a first adsorption column and a second adsorption column connected in series. The first adsorption column has a first gas inlet, and the second adsorption column has an adsorption product outlet. The first adsorption column is selected from activated carbon adsorption columns, modified activated carbon adsorption columns, molecular sieve adsorption columns, or zeolite adsorption columns, and the second adsorption column is a macroporous adsorption resin adsorption column. The distillation unit has a distillation inlet and a distillation gas outlet, with the distillation inlet and the adsorption product outlet connected via an adsorption product delivery pipeline. The precision filtration unit has a distillation gas inlet and an ultra-high purity titanium tetrachloride outlet, with the distillation gas inlet connected to the distillation gas outlet.

[0009] Furthermore, the diameters of the first adsorption column and the second adsorption column are independently selected from 25.4 to 76.2 mm, the height-to-diameter ratios are independently selected from (5 to 10):1, and the packing coefficients are independently selected from 80 to 90%.

[0010] Furthermore, the adsorbent in the first adsorption column has a particle size of 2–5 mm, a pore size of 2 nm–50 nm, and a specific surface area of ​​500–1500 m². 2 / g; The macroporous adsorption resin column is selected from macroporous iminodiacetic acid polystyrene resin adsorption column, macroporous aminophosphate polystyrene resin adsorption column or styrene-divinyl resin adsorption column with sulfonation degree ≥60%, and the pore size of the macroporous adsorption resin column is 10-50nm.

[0011] Furthermore, the distillation unit includes: a first distillation unit and a second distillation unit. The first distillation unit is provided with a distillation gas inlet, a top product outlet, and an intermediate product outlet. The second distillation unit is provided with an intermediate product inlet, a distillation gas outlet, and a bottom product outlet. The intermediate product outlet is connected to the intermediate product inlet.

[0012] Furthermore, both the first and second distillation units are packed towers, and the packing materials in the packed towers are independently selected from stainless steel θ-ring packing, triangular spiral packing, or glass spring packing.

[0013] Furthermore, the packing material in the packed tower is independently selected from 5mm double-layer stainless steel θ-ring packing or 5mm triangular spiral packing.

[0014] Furthermore, the precision filtration unit includes a first precision filtration device and a second precision filtration device arranged in series, wherein the filtration precision of the first precision filtration device and the second precision filtration device are independently selected from 0.03 to 0.1 μm.

[0015] Furthermore, the preparation system for ultra-high purity titanium tetrachloride also includes a pre-filtration device, which is installed on the adsorption product delivery pipeline. Preferably, the filtration accuracy of the pre-filtration device is 0.05–0.2 μm.

[0016] Another aspect of this application provides a method for preparing ultra-high purity titanium tetrachloride, wherein the purity of the ultra-high purity titanium tetrachloride is ≥99.99%. The method for preparing ultra-high purity titanium tetrachloride includes: subjecting industrial-grade titanium tetrachloride to a two-stage liquid-phase adsorption treatment to obtain an adsorption product, wherein the primary liquid-phase adsorbent used in the two-stage liquid-phase adsorption treatment is selected from one or more of the group consisting of activated carbon, modified activated carbon, molecular sieves and zeolites, and the secondary liquid-phase adsorbent is a macroporous adsorption resin; subjecting the adsorption product to distillation to obtain a distillation product; and subjecting the distillation product to precision filtration to obtain ultra-high purity titanium tetrachloride.

[0017] Furthermore, in the two-stage liquid phase adsorption process, the primary liquid phase adsorbent and the secondary liquid phase adsorbent are sequentially packed into the first adsorption column and the second adsorption column arranged in series, and the adsorption pressure of the first adsorption column and the second adsorption column are independently selected from 0.5 to 5 bar, and the temperature is independently selected from 10℃ to 50℃.

[0018] Furthermore, the purity of industrial-grade titanium tetrachloride is >99%, and the total amount of all impurities is less than 100 ppb.

[0019] Furthermore, the primary liquid phase adsorbent has a particle size of 2–5 mm, a pore size of 2 nm–50 nm, and a specific surface area of ​​500–1500 m². 2 / g, preferably, the molecular sieve adsorbent is selected from ZSM-5 and / or 13X, the zeolite adsorbent is selected from mordenite and / or chalcogenite; the macroporous adsorption resin is selected from one or more of the group consisting of macroporous iminodiacetic acid polystyrene resin, macroporous aminophosphate polystyrene resin, and styrene-divinyl resin with sulfonation degree ≥60%.

[0020] Furthermore, in the two-stage liquid phase adsorption treatment, the liquid flow rate is 20-200 mL / min, the diameters of the first adsorption column and the second adsorption column are independently selected from 25.4-76.2 mm, the height-to-diameter ratio is (5-10):1, and the packing coefficients are independently selected from 80-90%; preferably, in the two-stage liquid phase adsorption treatment, the liquid flow rate is 50-150 mL / min.

[0021] Further, the distillation process includes: subjecting the adsorbed product to a first distillation process to obtain an intermediate product; subjecting the intermediate product to a second distillation process to obtain a distilled product; wherein, in the first distillation process, the top pressure of the column is 30 kPa to 50 kPa, the top temperature of the column is 140 to 155 °C, the reflux feed ratio is 5 to 15, the number of theoretical plates is 10 to 35, and the low-boiling product accounts for 5 to 10 wt% of the feed; in the second distillation process, the top pressure of the column is 30 to 50 kPa, the top temperature of the column is 140 to 155 °C, the reflux feed ratio is 5 to 15, the number of theoretical plates is 10 to 35, and the high-boiling product accounts for 5 to 15 wt% of the feed.

[0022] Furthermore, the reflux feed ratio for the first distillation process is 10–15, and the number of theoretical plates is 20–30; the reflux feed ratio for the second distillation process is 10–15, and the number of theoretical plates is 20–30.

[0023] Furthermore, the precision filtration process includes a first precision filtration process and a second precision filtration process, and the filtration accuracy of the first precision filtration process is less than that of the second precision filtration process; preferably, the filtration accuracy of the first precision filtration process and the second precision filtration process is selected from 0.03 to 0.1 μm.

[0024] Furthermore, between the adsorption treatment and the distillation process, the method for preparing ultra-high purity titanium tetrachloride also includes: pre-filtration of the adsorption product; preferably, the filtration accuracy of the pre-filtration process is lower than that of the first precision filtration process; more preferably, the filtration accuracy of the pre-filtration process is 0.05 to 0.2 μm.

[0025] By applying the technical solution of this invention, a two-stage liquid-phase adsorption device composed of a specific type of adsorption column and an adsorbent with a specific pore size ratio can initially remove organic matter, metal ions, and non-metal ion impurities from industrial-grade titanium tetrachloride raw materials. Then, the product components are further purified by a distillation unit, and finally, a precision filtration unit effectively reduces the particulate matter content in the product, thereby improving product quality. Furthermore, the above-mentioned preparation system also has the advantages of simple preparation process and low equipment and preparation costs. Based on this, the preparation of ultra-high purity titanium tetrachloride using the ultra-high purity titanium tetrachloride preparation system provided in this application not only simplifies the process but also reduces process costs while improving product quality. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 This is a structural diagram of an ultra-high purity titanium tetrachloride preparation system provided for a typical embodiment of this application.

[0028] The above figures include the following reference numerals:

[0029] 10. Two-stage liquid phase adsorption device; 11. First adsorption column; 12. Second adsorption column; 20. Distillation unit; 21. First distillation device; 22. Second distillation device; 30. Precision filtration unit; 31. First precision filtration device; 32. Second precision filtration device; 40. Pre-filtration device. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0031] As described in the background section, existing processes for preparing ultra-high purity titanium tetrachloride cannot simultaneously achieve the goals of simple preparation, low impurity content, and low cost. To address these technical problems, this application provides a system for preparing ultra-high purity titanium tetrachloride, comprising: a two-stage liquid-phase adsorption device 10, a distillation unit 20, and a precision filtration unit 30. The two-stage liquid-phase adsorption device 10 includes a first adsorption column 11 and a second adsorption column 12 connected in series. The first adsorption column 11 has a first gas inlet, and the second adsorption column 12 has an adsorption product outlet. The first adsorption column 11 is selected from activated carbon adsorption columns, modified activated carbon adsorption columns, molecular sieve adsorption columns, or zeolite adsorption columns, and the second adsorption column 12 is a macroporous adsorption resin adsorption column. The distillation unit 20 has a distillation inlet and a distillation gas outlet, with the distillation inlet and adsorption product outlet connected via an adsorption product delivery pipeline. The precision filtration unit 30 has a distillation gas inlet and an ultra-high purity titanium tetrachloride outlet, with the distillation gas inlet connected to the distillation gas outlet.

[0032] The ultra-high purity titanium tetrachloride preparation system provided in this application utilizes a two-stage liquid-phase adsorption device 10 composed of a specific type of adsorption column and an adsorbent with a specific pore size ratio. This device can initially remove organic matter, metal ions, and non-metal ion impurities from industrial-grade titanium tetrachloride raw materials. Then, the product components are further purified by a distillation unit 20, and finally, a precision filtration unit 30 effectively reduces the particulate matter content in the product, thereby improving product quality. Furthermore, the preparation system also boasts advantages such as simple preparation process and low equipment and preparation costs. Therefore, the preparation of ultra-high purity titanium tetrachloride using the system provided in this application not only simplifies the process but also reduces costs while simultaneously improving product quality.

[0033] The two-stage liquid-phase adsorption device 10, filled with a specific adsorbent, can effectively reduce the content of metal ions and organic matter in titanium tetrachloride, and also effectively improve the purity of titanium tetrachloride in the product. In a preferred embodiment, the diameters of the first adsorption column 11 and the second adsorption column 12 are independently selected from 25.4 to 76.2 mm, the height-to-diameter ratios are independently selected from 5 to 10:1, and the filling coefficients are independently selected from 80 to 90%. The diameters, height-to-diameter ratios, and filling coefficients of the first adsorption column 11 and the second adsorption column 12 are not limited to the above ranges, and limiting them to the above ranges is beneficial to further improve the processing capacity of the two-stage liquid-phase adsorption device 10 for the raw gas, the purity of titanium tetrachloride in the product, and the safety of the process.

[0034] The combined use of the first adsorption column 11 and the second adsorption column 12 can significantly enhance the adsorption capacity for particulate matter in industrial-grade titanium tetrachloride feed gas and improve product purity. To further improve the purity of the target product, preferably, the adsorbent in the first adsorption column 11 has a particle size of 2–5 mm, a pore size of 2 nm–50 nm, and a specific surface area of ​​500–1500 m². 2 / g; Macroporous adsorption resin adsorption columns include, but are not limited to, macroporous iminodiacetic acid polystyrene resin adsorption columns, macroporous aminophosphate polystyrene resin adsorption columns, or styrene-divinyl resin adsorption columns with a sulfonation degree ≥60%, and the pore size of macroporous adsorption resin adsorption columns is 10-50 nm.

[0035] To avoid introducing oxygen into the feed gas, preferably, the two-stage liquid phase adsorption device 10 is purged and replaced with high-purity nitrogen before use, so that the oxygen content in the discharged nitrogen is ≤2ppm and the dew point is ≤-60℃, and then the purging is stopped.

[0036] The distillation unit 20 enables further purification of the product components. In a preferred embodiment, the distillation unit 20 includes a first distillation unit 21 and a second distillation unit 22. The first distillation unit 21 is provided with a distillation gas inlet, a top product outlet, and an intermediate product outlet; the second distillation unit 22 is provided with an intermediate product inlet, a distillation gas outlet, and a bottom product outlet, with the intermediate product outlet connected to the intermediate product inlet. Compared to a single distillation column, the above two-stage distillation column can further improve the purity of titanium tetrachloride in the final product gas.

[0037] To further improve the distillation effect, in a preferred embodiment, both the first distillation unit 21 and the second distillation unit 22 are packed columns, and the packing materials in the packed columns are independently selected from stainless steel θ-ring packing, triangular spiral packing, or glass spring packing. More preferably, the packing materials in the packed columns are independently selected from 5mm double-layer stainless steel θ-ring packing or 5mm triangular spiral packing.

[0038] The precision filtration unit 30 effectively reduces the particulate matter content in the distillation product, thereby further improving the purity of titanium tetrachloride in the product gas. In a preferred embodiment, the precision filtration unit 30 includes a first precision filter 31 and a second precision filter 32 arranged in series. The filtration precision of the first precision filter 31 and the second precision filter 32 are independently selected from 0.03 to 0.1 μm. The filtration precision of the first precision filter 31 and the second precision filter 32 includes, but is not limited to, the above range. Limiting it to the above range is beneficial to further improve the filtration efficiency of the precision filtration unit 30 for particulate matter, thereby further improving the purity of titanium tetrachloride in the product gas.

[0039] Preferably, the outer shell materials of the first precision filter device 31 and the second precision filter device 32 are independently selected from 316L stainless steel, PTFE (polytetrafluoroethylene), PFA (a copolymer of a small amount of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene), or PP (polypropylene), and preferably 316L stainless steel and PTFE materials that have been electroplated and polished; the filter element material is preferably PTFE, and more preferably, 0.05μm filter elements and 0.03μm filter elements are used in series to enhance the filtration effect.

[0040] In a preferred embodiment, the preparation system for ultra-high purity titanium tetrachloride further includes a pre-filtration device 40, which is disposed on the adsorption product conveying pipeline. The pre-filtration device 40 further removes particulate matter from the adsorption product, thereby further improving the purity of the final product gas. To further improve the filtration effect, more preferably, the filter element in the pre-filtration device 40 has a filtration accuracy of 0.05–0.2 μm, and more preferably 0.05 μm.

[0041] Preferably, the outer shell of the pre-filter 40 is made of 316L stainless steel, PTFE (polytetrafluoroethylene), PFA (a copolymer of a small amount of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene) or PP (polypropylene), and the inner wall is preferably made of 316L stainless steel or PTFE material that has been electroplated and polished. The filter element material is preferably PTFE.

[0042] Another aspect of this application provides a method for preparing ultra-high purity titanium tetrachloride, wherein the purity of the ultra-high purity titanium tetrachloride is ≥99.99%. The method for preparing ultra-high purity titanium tetrachloride includes: subjecting industrial-grade titanium tetrachloride to a two-stage liquid-phase adsorption treatment to obtain an adsorption product, wherein the primary liquid-phase adsorbent used in the two-stage liquid-phase adsorption treatment is selected from one or more of the group consisting of activated carbon, modified activated carbon, molecular sieves and zeolites, and the secondary liquid-phase adsorbent is a macroporous adsorption resin; subjecting the adsorption product to distillation to obtain a distillation product; and subjecting the distillation product to precision filtration to obtain ultra-high purity titanium tetrachloride.

[0043] By employing a two-stage liquid-phase adsorption process using specific types of adsorption columns and adsorbents with specific pore sizes, organic matter, metal ions, and non-metal ions can be initially removed from industrial-grade titanium tetrachloride raw materials. Further purification of the product components is then achieved through distillation, and finally, precision filtration effectively reduces the particulate matter content, thereby improving product quality. Furthermore, the above preparation process is simple and cost-effective. Based on this, the ultra-high purity titanium tetrachloride preparation method provided in this application is not only simple but also reduces process costs while improving product quality.

[0044] The combined use of a first adsorption column 11 and a second adsorption column 12 containing specific adsorbents can significantly enhance the adsorption capacity of the adsorption process for particulate matter in industrial-grade titanium tetrachloride feed gas and improve product purity. In a preferred embodiment, during the two-stage liquid-phase adsorption process, the first-stage liquid-phase adsorbent and the second-stage liquid-phase adsorbent are sequentially packed into the first adsorption column 11 and the second adsorption column 12 arranged in series. The adsorption pressures of the first adsorption column 11 and the second adsorption column 12 are independently selected from 0.5 to 5 bar, and the temperatures are independently selected from 10°C to 50°C. By pressurizing the first adsorption column 11 and the second adsorption column 12 and limiting the temperature within the above range, it is beneficial to improve the adsorption efficiency and adsorption effect of the two-stage liquid-phase adsorption process, thereby further improving the purity of the product gas.

[0045] The purity of raw materials has a significant impact on the adsorption effect and the service life of the adsorbent. In order to extend the service life of the adsorbent and improve its adsorption effect, preferably, the purity of industrial grade titanium tetrachloride is >99% and the total amount of impurities is less than 100 ppb.

[0046] In a preferred embodiment, the primary liquid phase adsorbent has a particle size of 2–5 mm, a pore size of 2 nm–50 nm, and a specific surface area of ​​500–1500 m². 2 / g. Compared to other adsorbents, using a primary liquid-phase adsorbent of the above specifications is beneficial for further improving the removal rate of impurities such as metal ions, thereby increasing the purity of the final product. More preferably, the molecular sieve adsorbent includes, but is not limited to, ZSM-5 and / or 13X, and the zeolite adsorbent includes, but is not limited to, mordenite and / or chalcogenite.

[0047] In a preferred embodiment, the macroporous adsorption resin is selected from one or more of the group consisting of macroporous iminodiacetic acid polystyrene resin, macroporous aminophosphate polystyrene resin, and styrene-divinyl resin with a sulfonation degree ≥60%. Compared with other macroporous adsorption resins, using the above-mentioned macroporous adsorption resins is beneficial to further improve the adsorption and purification effect of the two-stage liquid phase adsorption process on industrial-grade titanium tetrachloride feed gas.

[0048] In the two-stage liquid-phase adsorption process, the liquid flow rate, the diameter and height-to-diameter ratio of the first adsorbent and the second adsorption column, and the packing coefficient also affect the treatment effect. To further improve the adsorption effect of the two-stage liquid-phase adsorption process on industrial-grade titanium tetrachloride feed gas, in a preferred embodiment, the liquid flow rate is 20–200 mL / min, the diameters of the first adsorption column 11 and the second adsorption column 12 are independently selected from 25.4–76.2 mm, the height-to-diameter ratio is (5–10):1, and the packing coefficient is independently selected from 80–90%. More preferably, the liquid flow rate is 50–150 mL / min.

[0049] Distillation can separate impurities from titanium tetrachloride gas in the adsorption product. In a preferred embodiment, the distillation process includes: subjecting the adsorption product to a first distillation process to obtain an intermediate product; and subjecting the intermediate product to a second distillation process to obtain a distilled product. The first distillation process has a column top pressure of 30-50 kPa, a column top temperature of 140-155°C, a reflux feed ratio of 5-15, and 10-35 theoretical plates. The second distillation process also has a column top pressure of 30-50 kPa, a column top temperature of 140-155°C, a reflux feed ratio of 5-15, and 10-35 theoretical plates. Compared to other distillation processes, the first and second distillation processes described above are beneficial for further improving the purity of titanium tetrachloride in the product gas. To better enhance the synergistic effect of the first and second distillation processes, more preferably, in a preferred embodiment, the reflux feed ratio of the first distillation process is 10-15, the number of theoretical plates is 20-30, and the low-boiling product accounts for 5-10 wt% of the feed; the reflux feed ratio of the second distillation process is 10-15, the number of theoretical plates is 20-30, and the high-boiling product accounts for 5-15 wt% of the feed.

[0050] Precision filtration effectively reduces the particulate matter content in distillation products, thereby further improving the purity of titanium tetrachloride in the product gas. To further enhance the filtration effect, in a preferred embodiment, the precision filtration process includes a first precision filtration process and a second precision filtration process, with the filtration precision of the first precision filtration process being lower than that of the second precision filtration process. This is beneficial for improving the service life and filtration effect of the precision filtration device. More preferably, the filtration precision of the first and second precision filtration processes is selected from 0.03 to 0.1 μm. The combined use of these two stages of precision filtration further improves the filtration effect.

[0051] Between the adsorption treatment and distillation processes, the above-mentioned method for preparing ultra-high purity titanium tetrachloride further includes: pre-filtration of the adsorption product. The pre-filtration device can further remove particulate matter from the adsorption product, thereby further improving the purity of the final product gas. To improve its service life, the filtration accuracy of the pre-filtration process is lower than that of the first precision filtration process. To further improve the filtration effect, preferably, the filtration accuracy of the pre-filtration is 0.05–0.2 μm.

[0052] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0053] Example 1

[0054] according to Figure 1 The process flow shown involves 99.000 wt% industrial-grade titanium tetrachloride being pressurized with nitrogen before entering a two-stage liquid-phase adsorption unit 10. In the two-stage liquid-phase adsorption unit 10, the adsorbent in the first adsorption column 11 is modified activated carbon (particle size 2mm–4mm, pore size 2nm–50nm, specific surface area 1500m²). 2 / g (manufacturer: Jacobi, model: CS12X30), the above-mentioned industrial-grade titanium tetrachloride, after being adsorbed by the first adsorption column 11, enters the second adsorption column 12. The adsorbent in the second adsorption column 12 is Purolite brand D001 type. Both the first adsorption column 11 and the second adsorbent have a diameter of 2 inches and a length of 20 inches, are made of 316L stainless steel, and have electrolytically polished inner walls; the adsorption pressure is 2 bar, and the flow rate is controlled at 100 mL / min.

[0055] After adsorption by a two-stage liquid phase adsorption device 10, adsorption products are obtained. The adsorption products are then passed into a pre-filter device 40. The shell of the pre-filter device 40 is made of 316L stainless steel, the filter element is made of PTFE, and the filtration accuracy is 0.1μm.

[0056] The material obtained after adsorption by the pre-filter 40 is condensed and fed into the distillation unit 20. The distillation unit 20 includes a first distillation unit 21 and a second distillation unit 22 connected in series. The first distillation unit 21 has a column pressure of 50 kPa, a top temperature of 152°C, a reflux feed ratio of 10, 30 theoretical plates, and a low-boiling point product accounting for 10% of the feed. The pressure differential is controlled at 3–5 kPa. The intermediate product from the first distillation unit is pressurized by a pump and then enters the second distillation unit. The second distillation unit 22 has a column pressure of 50 kPa, a top temperature of 152°C, a reflux feed ratio of 10, 30 theoretical plates, a pressure differential controlled at 3–5 kPa, and a high-boiling point product accounting for 15% of the total feed. The overall system yield is 75%. The product is collected from the top of the second distillation unit.

[0057] The product collected from the top of the second distillation column enters the precision filtration unit 30 for precision filtration to obtain a qualified product. The distillation filtration unit is a two-stage precision filtration device connected in series. The outer shell of the two-stage precision filtration device is made of 316L stainless steel, and the filter element is made of PTFE. The filtration accuracy of the first-stage precision filtration is 0.05μm, and the filtration accuracy of the second-stage precision filtration is 0.03μm.

[0058] The titanium tetrachloride obtained by this process, after GC-MS analysis, showed a composition of 99.995%. ICP-MS analysis revealed a total impurity content of 2 ppbw. Particle size analysis showed the following particle sizes: 0.1 μm ≤ 10 particles / mL, 0.2 μm ≤ 5 particles / mL, and 0.5 μm ≤ 1 particle / mL.

[0059] Example 2

[0060] The difference from Example 1 is that the adsorbent in the first adsorption column 11 is a molecular sieve, specifically UOP 5A molecular sieve, with spherical particles having a diameter of 2-3 mm and a specific surface area of ​​700 m². 2 / g.

[0061] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.992% wt. ICP-MS analysis shows the total impurities in the product are 1.9 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 10 particles / mL, 0.2 μm ≤ 4 particles / mL, and 0.5 μm ≤ 1 particle / mL.

[0062] Example 3

[0063] The difference from Example 1 is that the adsorbent in the first adsorption column 11 is Zeolite ZSM-5 zeolite, with a particle size of 2-3 mm, a silica-alumina ratio ≥200, and a specific surface area of ​​500 m². 2 / g.

[0064] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.991% wt. ICP-MS analysis shows the total impurities in the product are 1.8 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 9 particles / mL, 0.2 μm ≤ 4 particles / mL, and 0.5 μm ≤ 1 particle / mL.

[0065] Example 4

[0066] The difference from Example 1 is that the adsorbent in the first adsorption column 11 is unmodified activated carbon, DAIZEN ACF coconut shell activated carbon, with a particle size of 2-5 mm and a specific surface area of ​​500 m². 2 / g.

[0067] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.991% wt. ICP-MS analysis shows the total impurities in the product are 5 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 15 particles / mL, 0.2 μm ≤ 6 particles / mL, and 0.5 μm ≤ 2 particles / mL.

[0068] Example 5

[0069] The difference from Example 1 is that the macroporous adsorption resin in the second adsorption column 12 is Lanxess Lewatit iminodiacetic acid polystyrene resin, with a particle diameter of 2-4 mm and a specific surface area of ​​200 m². 2 / g, exchange capacity 2eq / L.

[0070] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.993% wt. ICP-MS analysis shows the total impurities in the product are 4 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 15 particles / mL, 0.2 μm ≤ 8 particles / mL, and 0.5 μm ≤ 2 particles / mL.

[0071] Example 6

[0072] The difference from Example 1 is that the macroporous adsorption resin in the second adsorption column 12 is Rohm and Haas UP6040 styrene ion exchange resin, with a particle size of 2-3 mm and a specific surface area of ​​200 m². 2 / g, exchange capacity 2eq / L.

[0073] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.994% wt. ICP-MS analysis shows the total impurities in the product are 5 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 13 particles / mL, 0.2 μm ≤ 8 particles / mL, and 0.5 μm ≤ 2 particles / mL.

[0074] Example 7

[0075] The difference from Example 1 is that the top pressure of the first distillation process is 30 Pa, the top temperature is 155 °C, the reflux feed ratio is 5, and the theoretical number of plates is 35.

[0076] The second distillation process has a column top pressure of 50 kPa, a column top temperature of 155 °C, a reflux feed ratio of 15, and a theoretical number of plates of 10.

[0077] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.990% wt. ICP-MS analysis shows the total impurities in the product are 1.9 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 10 particles / mL, 0.2 μm ≤ 5 particles / mL, and 0.5 μm ≤ 1 particle / mL.

[0078] Example 8

[0079] The difference from Example 1 is that the top pressure of the first distillation process is 50 kPa, the top temperature is 140°C, the reflux feed ratio is 15, and the number of theoretical plates is 10.

[0080] The second distillation process has a column top pressure of 30 kPa, a column top temperature of 155°C, a reflux feed ratio of 5, and a theoretical number of 35 plates.

[0081] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.991% wt. ICP-MS analysis shows the total impurities in the product are 2.1 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 10 particles / mL, 0.2 μm ≤ 5 particles / mL, and 0.5 μm ≤ 1 particle / mL.

[0082] Comparative Example 1

[0083] The difference from Example 1 is that a single modified activated carbon adsorption column is used instead of the two-stage liquid phase adsorption device 10, and the modified activated carbon in the modified activated carbon adsorption column is the same as that in Example 1.

[0084] The titanium tetrachloride obtained by this process, after GC-MS analysis, has a purity of 99.900 wt%. ICP-MS analysis shows the total impurities in the product are 20 ppbw. Particle size analysis reveals the following particle sizes: 0.1 μm ≤ 10 particles / mL, 0.2 μm ≤ 5 particles / mL, and 0.5 μm ≤ 1 particle / mL.

[0085] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: compared with the prior art, the method provided in this application significantly improves the purity of titanium tetrachloride components, increases the efficiency of removing product impurities, and has a significant effect on improving product quality.

[0086] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for preparing ultra-high purity titanium tetrachloride, characterized in that, The preparation system for ultra-high purity titanium tetrachloride includes: A two-stage liquid phase adsorption device (10) includes a first adsorption column (11) and a second adsorption column (12) arranged in series. The first adsorption column (11) is provided with a first air inlet, and the second adsorption column (12) is provided with an adsorption product outlet. The first adsorption column (11) is selected from activated carbon adsorption column, modified activated carbon adsorption column, molecular sieve adsorption column or zeolite adsorption column, and the second adsorption column (12) is a macroporous adsorption resin adsorption column. A distillation unit (20) is provided with a distillation inlet and a distillation gas outlet. The distillation inlet and the adsorption product outlet are connected through an adsorption product conveying pipeline. A precision filtration unit (30) is provided with a distillation gas inlet and an ultra-high purity titanium tetrachloride outlet, wherein the distillation gas inlet is connected to the distillation gas outlet. The diameters of the first adsorption column (11) and the second adsorption column (12) are independently selected from 25.4 to 76.2 mm, the height-to-diameter ratios are independently selected from (5 to 10):1, and the packing coefficients are independently selected from 80 to 90%. The adsorbent in the first adsorption column (11) has a particle size of 2-5 mm, a pore size of 2 nm-50 nm, and a specific surface area of ​​500-1500 m². 2 / g; The macroporous adsorption resin column is selected from macroporous iminodiacetic acid polystyrene resin adsorption column, macroporous aminophosphate polystyrene resin adsorption column, or styrene-divinyl resin adsorption column with sulfonation degree ≥60%, and the pore size of the macroporous adsorption resin column is 10-50 nm.

2. The preparation system for ultra-high purity titanium tetrachloride according to claim 1, characterized in that, The distillation unit (20) includes: The first distillation unit (21) is provided with a distillation gas inlet, a top product outlet and an intermediate product outlet; The second distillation unit (22) is provided with an intermediate product inlet, a distillation gas outlet and a bottom product outlet, and the intermediate product outlet is connected to the intermediate product inlet.

3. The preparation system for ultra-high purity titanium tetrachloride according to claim 2, characterized in that, Both the first distillation unit (21) and the second distillation unit (22) are packed towers, and the packing in the packed towers is independently selected from stainless steel θ-ring packing, triangular spiral packing or glass spring packing.

4. The preparation system for ultra-high purity titanium tetrachloride according to claim 3, characterized in that, The packing materials in the packed tower are independently selected from 5mm double-layer stainless steel θ-ring packing or 5mm triangular spiral packing.

5. The preparation system for ultra-high purity titanium tetrachloride according to claim 1, characterized in that, The precision filtration unit (30) includes a first precision filtration device (31) and a second precision filtration device (32) arranged in series. The filtration accuracy of the first precision filtration device (31) and the second precision filtration device (32) are independently selected from 0.03 to 0.1 μm.

6. The preparation system for ultra-high purity titanium tetrachloride according to claim 5, characterized in that, The preparation system for ultra-high purity titanium tetrachloride also includes a pre-filtration device (40), which is installed on the adsorption product delivery pipeline. The filtration accuracy of the pre-filtration device (40) is 0.05 to 0.2 μm.

7. A method for preparing ultra-high purity titanium tetrachloride, wherein the ultra-high purity titanium tetrachloride has a purity ≥99.99%, characterized in that, The preparation method of the ultra-high purity titanium tetrachloride includes: Industrial-grade titanium tetrachloride is subjected to two-stage liquid-phase adsorption treatment to obtain adsorption products. The first-stage liquid-phase adsorbent used in the two-stage liquid-phase adsorption treatment is selected from one or more of the group consisting of activated carbon, modified activated carbon, molecular sieve and zeolite, and the second-stage liquid-phase adsorbent is macroporous adsorption resin. The adsorbed product is subjected to distillation to obtain a distilled product. The distillation product is then precisely filtered to obtain the ultra-high purity titanium tetrachloride. in, In the two-stage liquid phase adsorption treatment, the first-stage liquid phase adsorbent and the second-stage liquid phase adsorbent are sequentially filled into the first adsorption column (11) and the second adsorption column (12) arranged in series. The adsorption pressure of the first adsorption column (11) and the second adsorption column (12) are independently selected from 0.5 to 5 bar, and the temperature is independently selected from 10℃ to 50℃. The primary liquid phase adsorbent has a particle size of 2–5 mm, a pore size of 2 nm–50 nm, and a specific surface area of ​​500–1500 m². 2 / g; The distillation process includes: The adsorption product is subjected to a first distillation process to obtain an intermediate product. The intermediate product is subjected to a second distillation process to obtain the distilled product. The top pressure of the first distillation process is 30 kPa to 50 kPa, the top temperature is 140 to 155 °C, the reflux feed ratio is 5 to 15, the theoretical number of plates is 10 to 35, and the low-boiling product accounts for 5 to 10 wt% of the feed. The second distillation process has a column top pressure of 30-50 kPa, a column top temperature of 140-155 °C, a reflux feed ratio of 5-15, a theoretical plate number of 10-35, and a high-boiling product rate of 5-15 wt% of the feed.

8. The method for preparing ultra-high purity titanium tetrachloride according to claim 7, characterized in that, The molecular sieve adsorbent is selected from ZSM-5 and / or 13X, the zeolite adsorbent is selected from mordenite and / or chalcogenite, and the macroporous adsorption resin is selected from one or more of the following groups: macroporous iminodiacetic acid polystyrene resin, macroporous aminophosphate polystyrene resin, and styrene-divinyl resin with a sulfonation degree ≥60%.

9. The method for preparing ultra-high purity titanium tetrachloride according to claim 7, characterized in that, The reflux feed ratio of the first distillation process is 10-15, and the number of theoretical plates is 20-30; the reflux feed ratio of the second distillation process is 10-15, and the number of theoretical plates is 20-30.

10. The method for preparing ultra-high purity titanium tetrachloride according to claim 7, characterized in that, The industrial-grade titanium tetrachloride has a purity >99% and the total amount of impurities is less than 100 ppb.

11. The method for preparing ultra-high purity titanium tetrachloride according to claim 7, characterized in that, In the two-stage liquid phase adsorption treatment, the liquid flow rate is 20-200 mL / min, the diameters of the first adsorption column (11) and the second adsorption column (12) are independently selected from 25.4-76.2 mm, the height-to-diameter ratio is (5-10):1, and the packing coefficients are independently selected from 80-90%.

12. The method for preparing ultra-high purity titanium tetrachloride according to claim 7, characterized in that, The precision filtration process includes a first precision filtration process and a second precision filtration process, wherein the filtration precision of the first precision filtration process is less than that of the second precision filtration process. The filtration accuracy of the first precision filtration process and the second precision filtration process is selected from 0.03 to 0.1 μm.

13. The method for preparing ultra-high purity titanium tetrachloride according to claim 12, characterized in that, Between the adsorption treatment and distillation process, the method for preparing ultra-high purity titanium tetrachloride further includes: pre-filtration of the adsorption product; the filtration accuracy of the pre-filtration process is lower than that of the first precision filtration process, and the filtration accuracy of the pre-filtration process is 0.05 to 0.2 μm.

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