Purification method of electronic-grade n-octane

Abstract

The invention discloses a method for purifying electronic-grade n-octane, which adopts special catalyst particles and a special complexing purification method, and the catalyst is formed by loading tungsten oxide powder, cobalt powder, nickel powder, copper powder and chromium powder on a ceramic matrix; special complexing purification is used, urea, isopropanol and water are mixed evenly, then a complexing solution is used for complexing crude n-octane, standing and settling are conducted, and a urea complex is fully settled and crystallized; after the complex is separated out, washing, finally heating the urea complex to decompose the urea complex, and separating a wax liquid phase; washing and distilling the wax liquid phase to obtain complexed dewaxed purified n-octane; then, filtering, dewatering, rectifying and removing impurities to obtain a final product; and finally, packaging the final product in a quartz container in a vacuum cavity to obtain the product. The method provided by the invention has the characteristics of 8N-grade purity, comprehensive purification by multiple methods, high rectification efficiency, high yield, and simple and easy separation of impurity components.

Description

Technical Field

[0001] The present invention relates to a high-purity semiconductor dopant, and particularly to a purification method for electronic-grade n-octane. Background Art

[0002] Doping of semiconductors is to improve the electrical properties of semiconductor devices, and many electrical characteristics of semiconductors are related to the impurity concentration of doping.

[0003] Most of the industrial-grade n-octane raw materials in the prior art are obtained by separation in petrochemical industry. They have many types of impurities, and it can be seen from the GC spectrum that the content of substances with boiling points close to that of n-octane is relatively high and difficult to remove. The yield of synthesizing n-octane by synthesis methods is mostly low (50% or less), and the raw materials of the methods with high yield are also obtained by petroleum separation. For example, using 1-octene to prepare n-octane, the n-octane obtained by this method also has the problem of a large variety of impurities, and the substances with boiling points close to that of octane are its isomers.

[0004] In the current prior art, there is no related technology to solve the above problems. At present, a purification method for electronic-grade n-octane with 8N purity, comprehensive purification by multiple methods, high rectification efficiency and high yield is needed. Summary of the Invention

[0005] The present invention aims to provide a purification method for electronic-grade n-octane with 8N purity, comprehensive purification by multiple methods, high rectification efficiency, high yield, and simple impurity components that are easy to separate.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A purification method for electronic-grade n-octane, the purification method includes the following stages: S1: Raw material preparation ① Raw material preparation: Prepare sufficient industrial n-octane, hydrogen, urea, isopropanol, and water; ② Tooling and equipment preparation: Prepare catalyst particles with tungsten oxide powder, cobalt powder, nickel powder, copper powder, and chromium powder carried on a ceramic matrix, a fixed-bed reactor, a complexation reaction device provided with a stirrer and a reflux condenser, a water bath constant temperature device, a filter molecular sieve, a microporous quartz filter with a filtration pore size of 0.01 μm, a quartz rectification column, a filtration device provided with a PTFE filter element with a pore size of 0.02 / 0.01 μm, a vacuum chamber with a vacuum degree of 1×10 -4 Pa to 1×10 -3 Pa, and a quartz encapsulation container; The transmission pipelines of all equipment are made of polytetrafluoroethylene tubes; S2: Crude distillation ① Load the catalyst particles prepared in step ② of stage S1 into the isothermal section of the fixed-bed reactor prepared in step ② of stage S1. Keep the system pressure constant at 2 MPa to 3 MPa, and introduce the hydrogen prepared in step ① of stage S1 at 250 °C to 270 °C for 80 min to 120 min to keep the catalyst in a reduced state; ② Raise the temperature of the reaction system in step ① to 420 °C to 480 °C, and then introduce the gasified industrial n-octane in this temperature range to carry out conversion in the fixed-bed reactor. The mass hourly space velocity of industrial n-octane is 3 h -1 ~4 h -1 , and the feed volume flow ratio is hydrogen to obtain de-isomerized crude purified n-octane; S3: Complexation purification ① Mix urea, isopropyl alcohol, and water prepared in step ① of stage S1 in a mass ratio of (1.9 to 2):(2 to 2.1):1, heat and stir evenly. After forming a homogeneous liquid mixture, cool the homogeneous liquid mixture to 45 °C; ② Inject the homogeneous liquid mixture obtained in step ① into the water bath constant temperature device prepared in step ② of stage S1 to maintain the temperature, and then add the purified n-octane obtained in step ② of stage S2 into it and maintain the system temperature; Subsequently, control the water bath constant temperature device to make the temperature of the reaction system drop from 45 °C at a rate of 1 °C / min to the required final temperature until the reaction is completed to obtain a urea complex suspension; ③ Let the reaction system of the urea complex suspension obtained in step ② stand and settle to fully settle and crystallize the urea complex; After separating the complex, wash the solid complex alternately with an organic solvent and water to remove the uncomplexed substances attached to the surface of the complex. Finally, heat the urea complex to decompose it and separate the liquid phase; After washing and distilling the liquid phase, obtain complexation-purified n-octane; S4: Rectification ① Use the filter molecular sieve prepared in step ② of stage S1 and the ultra-micro pore quartz filter with a filtration pore diameter of 0.01 μm to filter the complexation-purified n-octane obtained in step ③ of stage S3 to obtain water-removed and filtered n-octane; ② Use the quartz rectification column prepared in step ② of stage S1 to rectify the water-removed and filtered n-octane obtained in the step. Before rectification, use vacuum and inert atmosphere to replace the gas in the rectification system. After replacement, ensure that the system is in a slightly positive pressure state to ensure that environmental air will not enter the system to affect rectification to obtain rectified n-octane; ③ Filter the rectified n-octane using the filtering device prepared in step ② of stage S1 to remove the impurity solid particles brought by the system to obtain solid-removed n-octane; S5: Detection ① Detect the solid-removed n-octane obtained in step ③ of stage S4. It is required that the impurity content is not higher than 0.000001%, the moisture content is not more than 2 ppm, and the n-octane content is not less than 99.9% to obtain the target n-octane. S6: Encapsulation ① Encapsulate the n-octane qualified in step ① of stage S5 in the vacuum chamber prepared in step ② of stage S1 using the quartz encapsulation container prepared in step ② of stage S1. After the encapsulation is completed and sealed, the required electronic-grade n-octane is obtained.

[0007] Compared with the prior art, due to the adoption of the above technical solutions, the present invention has the following advantages: (1) The complexing dewaxing separation technology used in the present invention is different from general purification technologies, but can be complementary to the existing commonly used technologies. Its main function is to utilize the molecular structure principle and the molecular characteristics of normal paraffins for purification, and is particularly suitable for adsorption after rough distillation. The purification method adopted by the present invention not only has simple process conditions, low energy consumption, simple equipment, low equipment maintenance frequency, short cycle period, and no special requirements for raw materials, but also has very good comprehensive purification effects. Moreover, the catalytic purification, molecular sieve adsorption method and urea complexing method of the present invention are combined, and the purification effects are complementary.

[0008] (2) The present invention provides a catalytic purification method for the reaction of converting isoparaffins into normal paraffins. The catalyst provided by the present invention does not need to add halogen components and sulfur elements, avoiding problems such as component loss, environmental pollution and equipment corrosion; in addition, since the catalyst components are stable and not easy to lose, hydrogen can also be used for reduction, so that the catalyst has a good service life and regeneration performance.

[0009] Therefore, the present invention has the characteristics of 8N-level purity, comprehensive purification by multiple methods, high rectification efficiency, high yield, and simple impurity components and easy separation. Specific Embodiments Embodiment

[0010] A purification method for electronic-grade n-octane, the purification method comprising the following stages: S1: Raw material preparation ① Raw material preparation: Prepare sufficient industrial n-octane, hydrogen, urea, isopropanol, and water; ② Tooling and equipment preparation: Prepare catalyst particles with tungsten oxide powder, cobalt powder, nickel powder, copper powder, and chromium powder carried on a ceramic matrix, a fixed-bed reactor, a complexing reaction device equipped with a stirrer and a reflux condenser, a water bath constant temperature device, a filter molecular sieve, a microporous quartz filter with a filtration pore size of 0.01 μm, a quartz rectification column, and a filtration device equipped with a PTFE filter element with a pore size of 0.02 / 0.01 μm, and a vacuum degree of 1×10 -4 Pa~1×10-3 A vacuum chamber of Pa and a quartz encapsulation container; all transfer pipelines of the equipment are made of polytetrafluoroethylene tubes; S2: Crude distillation ① Load the catalyst particles prepared in step ② of stage S1 into the isothermal section of the fixed-bed reactor prepared in step ② of stage S1, keep the system pressure constant at 2 MPa to 3 MPa, and introduce the hydrogen prepared in step ① of stage S1 at 250 °C to 270 °C for 80 min to 120 min to keep the catalyst in a reduced state; ② Raise the temperature of the reaction system in step ① to 420 °C to 480 °C, and then introduce the vaporized industrial n-octane in this temperature range to carry out conversion in the fixed-bed reactor. The mass hourly space velocity of the industrial n-octane is 3 h -1 ~4 h -1 , and the feed volume flow ratio is hydrogen to obtain de-isomerized and roughly purified n-octane; S3: Complexation purification ① Mix urea, isopropyl alcohol, and water prepared in step ① of stage S1 in a mass ratio of (1.9 to 2):(2 to 2.1):1, heat and stir evenly. After forming a homogeneous liquid-phase mixture, cool the homogeneous liquid-phase mixture to 45 °C; ② Inject the homogeneous liquid-phase mixture obtained in step ① into the water bath constant temperature device prepared in step ② of stage S1 to keep the temperature, and then add the purified n-octane obtained in step ② of stage S2 into it and maintain the system temperature; then control the water bath constant temperature device to make the temperature of the reaction system drop from 45 °C at a rate of 1 °C / min to the required final temperature until the reaction is completed to obtain a urea complex suspension; ③ Let the reaction system of the urea complex suspension obtained in step ② stand and settle to make the urea complex fully settle and crystallize; after separating the complex, wash the solid-phase complex alternately with an organic solvent and water to remove the uncomplexed substances attached to the surface of the complex, and finally heat the urea complex to decompose it and separate the liquid phase; after washing and distilling the liquid phase with water, obtain complexation-purified n-octane; S4: Rectification ① Use the filter molecular sieve prepared in step ② of stage S1 and the microporous quartz filter with a filtration pore size of 0.01 μm to perform water removal filtration on the complexation-purified n-octane obtained in step ③ of stage S3 to obtain water-removed and filtered n-octane; ② Use the quartz rectification column prepared in step ② of stage S1 to rectify the water-removed and filtered n-octane obtained in the step. Before rectification, use vacuum and inert gas to replace the gas in the rectification system. After replacement, ensure that the system is in a slightly positive pressure state to ensure that ambient air will not enter the system and affect the rectification to obtain rectified n-octane; ③ Filter the rectified n-octane with the filter device prepared in step ② of stage S1 to remove the impurity solid particles brought by the system to obtain solid-free n-octane; S5: Detection ① Detect the solid-removed n-octane obtained in step ③ of stage S4. It is required that the impurity content is not higher than 0.000001%, the moisture content is not more than 2 ppm, and the n-octane content is not less than 99.9% to obtain the target n-octane. S6: Encapsulation ① Encapsulate the n-octane that has passed the inspection in step ① of stage S5 in the vacuum chamber prepared in step ② of stage S1 using the quartz encapsulation container prepared in step ② of stage S1. After the encapsulation is completed and sealed, the required electronic-grade n-octane is obtained.

[0011] The electronic-grade tetramethylcyclotetrasiloxane obtained according to this embodiment has the characteristics of 8N-grade purity, comprehensive purification by multiple methods, high rectification efficiency, high yield, and simple impurity components that are easy to separate.

[0012] The above description of the disclosed embodiments is only to enable those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for purifying electronic grade n-octane, characterized in that: The purification method The following phases are included: S1: Raw material preparation ① Raw material preparation: prepare sufficient industrial n-octane, hydrogen, urea, isopropanol and water; ② Preparation of tools and equipment: Prepare catalyst particles with ceramic matrix loaded with tungsten oxide powder, cobalt powder, nickel powder, copper powder, and chromium powder, fixed bed reactor, complex reaction device equipped with a stirrer and reflux condenser, water bath thermostat, water filter molecular sieve, microporous quartz filter with a filtration aperture of 0.01 μm, quartz distillation tower, filtration device equipped with 0.02 / 0.01 μm PTFE filter element, vacuum degree 1×10 -4 Pa~1×10 -3 Pa vacuum chamber, quartz packaging container; all equipment transmission pipelines are made of polytetrafluoroethylene tubes; S2: Crude distillation ① Load the catalyst particles prepared in step ② of stage S1 into the constant temperature section of the fixed bed reactor prepared in step ② of stage S1, keep the system pressure constant at 2MPa~3MPa, and introduce the hydrogen prepared in step ① of stage S1 at 250℃~270℃ for 80min~120min to keep the catalyst in a reduced state; ② The reaction system in step ① is heated to 420°C~480°C, and then the gasified industrial n-octane is introduced into the fixed bed reactor to be converted. The mass space velocity of industrial n-octane is 3h -1 ~4h -1 , the feed volume flow ratio is hydrogen, and deisomerization crude purified n-octane is obtained; S3: Complexation purification ① Mix the urea, isopropanol and water prepared in step ① of stage S1 in a mass ratio of (1.9-2): (2-2.1): 1, heat and stir evenly, and after a uniform liquid phase mixture is formed, cool the uniform liquid phase mixture to 45° C.; ② The uniform liquid mixture obtained in step ① is injected into the water bath thermostat prepared in step ② of stage S1 to maintain the temperature, and then the purified n-octane obtained in step ② of stage S2 is added thereto and the system temperature is maintained; then the water bath thermostat is controlled to reduce the temperature of the reaction system from 45° C. to the desired final temperature at a rate of 1° C. / min until the reaction is completed, thereby obtaining a urea complex suspension; ③ The urea complex suspension reaction system obtained in step ② is allowed to stand and settle to allow the urea complex to fully settle and crystallize; after separating the complex, the solid phase complex is washed alternately with an organic solvent and water to remove the uncomplexed substances attached to the surface of the complex, and finally the urea complex is heated to decompose it and separate the liquid phase; the liquid phase is washed with water and distilled to obtain the complex purified n-octane; S4: Distillation ① Using the water-filtering molecular sieve prepared in step ② of stage S1 and a microporous quartz filter with a filtration pore size of 0.01 μm, the complex-purified n-octane obtained in step ③ of stage S3 is dehydrated and filtered to obtain dehydrated and filtered n-octane; ② Using the quartz distillation tower prepared in step ② of stage S1 to distill the dehydrated and filtered n-octane obtained in step ②, before distillation, the distillation system is gas-displaced by using vacuum and inert atmosphere, and after the displacement, the system is kept in a slightly positive pressure state to ensure that ambient air does not enter the system and affect the distillation to obtain distilled n-octane; ③ Using the filtering device prepared in step ② of stage S1 to filter and distill the n-octane, remove the impurity solid particles brought by the system, and obtain the desolidified n-octane; S5: Detection ① Testing the desolidified n-octane obtained in step ③ of stage S4, requiring the impurity content to be no higher than 0.000001%, the moisture content to be no greater than 2 ppm, and the n-octane content to be no less than 99.9%, to obtain the target n-octane; S6: Encapsulation ① The qualified n-octane detected in step ① of stage S5 is packaged in the vacuum chamber prepared in step ② of stage S1 using the quartz packaging container prepared in step ② of stage S1. After the packaging is completed and sealed, the required electronic grade n-octane is obtained.