Method and device for preparing electronic-grade n-hexane

Abstract

The invention relates to the field of chemical engineering, in particular to an n-hexane separation technology, and more particularly relates to a method and a device for preparing electronic-grade n-hexane. The method for preparing the electron n-hexane comprises the following steps: S1, introducing an adsorbent into an n-hexane raw material to remove moisture in the n-hexane, and then carrying out catalytic hydrogenation reaction to obtain crude n-hexane; and S2, carrying out primary filtration on the material subjected to catalytic hydrogenation, then carrying out light component removal and heavy component removal two-stage rectification to obtain high-purity n-hexane, and carrying out secondary filtration on the high-purity n-hexane to obtain the electronic-grade n-hexane. The device for preparing the electronic-grade n-hexane comprises a raw material tank, an adsorption tower, a catalytic hydrogenation reactor, an intermediate tank, a light component removal tower, a heavy component removal tower and a product tank which are connected in sequence. According to the preparation method and device, high-purity electronic-grade n-hexane meeting the strict requirements of the semiconductor industry can be produced, the process steps are simple, industrial production is easy to achieve, the product quality is stable and reliable, and high economic and social benefits are achieved.

Description

Technical Field

[0001] The present application relates to the field of chemical industry, specifically to a n-hexane separation technology, and more specifically to a method and device for preparing electronic grade n-hexane. Background Art

[0002] The molecular formula of n-hexane is C6H 14 , flammable liquid. The raw material of n-hexane comes from the separation of the raffinate oil (containing 11% to 13% hexane) of the platinum reforming unit. The raffinate oil is distilled and separated to remove light components and reorganize to obtain a fraction containing 60% to 80% n-hexane. Double-tower continuous distillation is used, and then catalytic hydrogenation is used to remove unsaturated hydrocarbons such as benzene to obtain qualified industrial-grade n-hexane. In industrial production, n-hexane is widely used in the manufacture of plastics, textiles, coatings, adhesives and other products. With the development of emerging industries, such as the rapid growth of electronics and automobiles, the market for n-hexane has also been expanded, especially in the manufacturing of electronic products and the development of new energy technologies, n-hexane plays a key role as an important solvent.

[0003] The Chinese patent with the announcement number CN104744196B discloses a method for purifying an organic solvent n-hexane, wherein impurities in the raw material n-hexane are removed by processes such as modified activated carbon adsorption to obtain a high-purity organic solvent n-hexane. The n-hexane with a purity of ≥99% (wt%) can be obtained, which meets the high purity requirements of chromatographic-grade reagents, so that the purified n-hexane can be applied to the fields of chromatographic analysis, chromatographic separation, chromatographic preparation, etc., expanding the scope of application. The Chinese patent with the announcement number CN107216231A discloses a method for purifying electronic-grade n-hexane, wherein the crude n-hexane is reacted with a decolorizing agent, then passed through a dehydrating agent, and finally passed through an extractive distillation tower with a mixture of dimethyl phthalate and DMF as an extractant. However, its purity is up to 99.55%. The n-hexane obtained by the above two purification methods cannot meet the needs of the electronics industry, but its purity still cannot meet the needs of electronic products.

[0004] The Chinese patent with the announcement number CN118373724A discloses a method for preparing high-purity n-hexane, which comprises adding industrial-grade n-hexane to analytical-grade sulfuric acid, stirring, and standing to separate the n-hexane; further removing impurities from the n-hexane by means of a modified molecular sieve; and finally obtaining high-purity n-hexane by adsorption with long-wave ultraviolet light modified activated carbon. The industrial-grade n-hexane removed impurities by adsorption with analytical-grade sulfuric acid is successively subjected to a water vapor modified molecular sieve removal treatment and a long-wave ultraviolet light modified activated carbon adsorption treatment to directly obtain chromatographic-grade high-purity n-hexane with a purity of not less than 99.99%. However, in this method, analytical-grade sulfuric acid is selected as the preliminary dehydration and impurity removal substance. Long-term use will not only cause a waste of sulfuric acid, but may also corrode equipment.

[0005] At present, domestic enterprises are still stuck in the production of high-purity n-hexane by various distillation methods, but the output is very small and the purification index is imperfect, which does not meet the existing electronic-grade product index. High-purity n-hexane products in the domestic market mainly rely on imports. With the rapid development of the electronics industry, the n-hexane market is facing new opportunities and growth space, and the electronic-grade high-purity n-hexane market has broad prospects. Therefore, it is urgent to propose a method and device for preparing electronic-grade n-hexane to alleviate the current dilemma of small output of high-purity n-hexane and imperfect purification index. Summary of the invention

[0006] In view of the fact that domestic enterprises are still stuck in producing high-purity n-hexane by various distillation methods, the output is very small and the purification indicators are imperfect, which does not meet the existing electronic-grade product indicators, etc., this application proposes a method and device for preparing electronic-grade n-hexane.

[0007] The technical solution of this application:

[0008] On the one hand, the present application provides a method for preparing electronic grade n-hexane, comprising the following steps:

[0009] Step S1. passing the n-hexane raw material into an adsorbent to remove water from the n-hexane, and then performing a catalytic hydrogenation reaction to obtain crude n-hexane;

[0010] Step S2: primary filtering the catalytically hydrogenated material to remove particulate matter, and then performing two-stage distillation for light and heavy fraction removal to obtain high-purity n-hexane, and secondary filtering the high-purity n-hexane to obtain electronic-grade n-hexane.

[0011] Preferably, the n-hexane raw material is of industrial grade, and the content of n-hexane is greater than or equal to 99%.

[0012] Preferably, the adsorbent is 4A grade molecular sieve, and the adsorption temperature is 20-50°C.

[0013] Preferably, the catalyst for the catalytic hydrogenation reaction is a platinum-tin catalyst, and the temperature of the catalytic reaction is 200-400°C.

[0014] Preferably, the temperature for light removal is 70-150°C, the reflux ratio is 5-10, the pressure is P1, and the range of P1 is 0.1MPa<P1≤0.2MPa; the temperature for heavy removal is 80-160°C, the reflux ratio is 5-10, the pressure is P2, the range of P2 is 0.1MPa≤P2<0.2MPa, and P2 is less than P1.

[0015] In a second aspect, the present application provides an apparatus for preparing electronic grade n-hexane, characterized in that it comprises a raw material tank, an adsorption tower, a catalytic hydrogenation reactor, an intermediate tank, a light removal tower, a heavy removal tower and a product tank;

[0016] The raw material tank is communicated with the adsorption tower, one end of the adsorption tower away from the raw material tank is communicated with the bottom of the catalytic hydrogenation reactor, one end of the catalytic hydrogenation reactor away from the adsorption tower is communicated with the top of the intermediate tank through a first pipeline, the bottom of the intermediate tank is communicated with the lower part of the light removal tower, the bottom of the light removal tower is communicated with the heavy removal tower, the upper part of the heavy removal tower is communicated with the product tank, and the bottom of the product tank is connected with a second pipeline.

[0017] Preferably, the first pipe is provided with a first filter, the second pipe is provided with a second filter, and both the first filter and the second filter are high-density polyethylene filters with a pore size of 0.1 to 2 μm.

[0018] Preferably, the de-heavy tower, de-light tower and product tank are all electropolished or lined with PFA.

[0019] The present application provides an efficient, stable and economical method for preparing electronic grade n-hexane, and its beneficial effects are mainly reflected in the following aspects:

[0020] (1) In the present application, the n-hexane raw material is first adsorbed to remove moisture, and a 4A grade molecular sieve is used as an adsorbent, which can effectively remove moisture from the n-hexane and provide a dry raw material for the subsequent catalytic hydrogenation reaction, thereby preventing catalyst poisoning and improving the reaction efficiency.

[0021] (2) Since methylcyclopentane and n-hexane have similar boiling points, it is difficult to effectively remove them using traditional distillation methods. The present application uses a platinum-tin catalyst for catalytic hydrogenation reaction. Under the action of the catalyst, it can react with the methylcyclopentane in n-hexane to form a component with a boiling point significantly different from that of n-hexane. Subsequent distillation can further improve the purity of n-hexane.

[0022] (3) The present invention ensures high purity of the product by adopting a two-stage distillation process (i.e., light fraction removal and heavy fraction removal). First, the light components in the product are removed by a light fraction removal step, and then the heavy components are removed by a heavy fraction removal step.

[0023] (4) The present application provides a first filter on the third pipe and a second filter on the seventh pipe, both of which are high-density polyethylene filters with a pore size of 0.1 to 2 μm, which effectively remove particulate matter and improve the cleanliness of the product. At the same time, the de-heavy tower, de-light tower and product tank are treated by electrolytic polishing or PFA lining, which effectively reduces the contamination of metal ions and further ensures the chemical stability and purity of the product.

[0024] (5) The device of the present application can form a continuous production process to improve production efficiency and operational convenience.

[0025] In summary, the preparation method and device of the present invention can not only produce high-purity electronic-grade n-hexane that meets the strict requirements of the semiconductor industry, but also has simple process steps, is easy to realize industrial production, has stable and reliable product quality, and has high economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the device for preparing electronic grade n-hexane for this application.

[0027] Figure symbols: 1. Raw material tank; 2. Adsorption tower; 3. Catalytic hydrogenation reactor; 4. First pipeline; 5. First filter; 6. Intermediate tank; 7. Light removal tower; 8. Heavy removal tower; 9. Product tank; 10. Second pipeline; 11. Second filter. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of the present application are described in detail below in combination with the preferred embodiments.

[0029] Device Embodiment

[0030] See also Figure 1 The present embodiment provides a device for preparing electronic grade n-hexane, comprising a raw material tank 1, in which industrial grade n-hexane raw material is stored in advance for standby use, the n-hexane raw material first enters an adsorption tower 2 along a pipeline, in which water in the n-hexane is removed, and then the crude n-hexane product enters a catalytic hydrogenation reactor 3 along a pipeline, and methylcyclopentane with a boiling point close to that of n-hexane in the crude n-hexane product is converted into methylpentane and n-hexane, which is convenient for subsequent distillation. After the material after the catalytic hydrogenation reaction comes out of the catalytic hydrogenation reactor 3, it passes through the first filter 5 on the first pipeline 4 to remove the catalyst and adsorbent particles that may come out with the gas. The n-hexane after the primary filtration enters the intermediate tank 6 for cooling, and then the pressure is increased in the intermediate tank 6. The crude n-hexane in the intermediate tank 6 is pressed into the light removal tower 7 through the pipeline through the pressure difference. In the light removal tower 7, the light component is extracted from the top of the light removal tower 7, and the other components enter the bottom of the light removal tower 7. The material in the bottom of the light removal tower 7 is sampled and analyzed. After the analysis is qualified, it enters the de-weighting tower 8 along the pipeline. In the de-weighting tower 8, the heavy component and most of the metal ions are extracted from the bottom of the de-weighting tower 8. The high-purity n-hexane enters the product tank 9 from the top of the de-weighting tower 8 along the pipeline, and then passes through the second filter 11 on the second pipeline 10 at the bottom of the product tank 9 to further filter and remove particulate matter. Finally, electronic grade n-hexane is obtained for charging and use.

[0031] The first filter 5 and the second filter 11 are both made of high-density polyethylene filters with a pore size of 0.1 to 2 μm.

[0032] The de-heavy tower 8, the de-light tower 7 and the product tank 9 are all electropolished or lined with PFA to maintain the stability of the product.

[0033] There are two adsorption towers 2, one of which is spare.

[0034] Based on the apparatus for preparing electronic-grade n-hexane provided in the equipment embodiment, embodiments 1 to 4 provide a method for preparing electronic-grade n-hexane.

[0035] Example 1

[0036] This embodiment provides a method for preparing electronic grade n-hexane, comprising the following steps:

[0037] Step S1. passing an industrial-grade n-hexane raw material having a n-hexane content greater than 99% into an adsorbent 4A molecular sieve to remove moisture from the n-hexane, wherein the adsorption temperature is 45°C. In order to recycle the adsorbent, the adsorbent is dehydrated at a desorption temperature of 200°C; then a catalytic hydrogenation reaction is performed to obtain crude n-hexane, using a platinum-tin catalyst, and the catalytic reaction temperature is 350°C.

[0038] Step S2. The catalytic hydrogenation material is primary filtered to remove particulate matter, and then the light removal and heavy removal two-stage distillation are performed to obtain high-purity n-hexane, wherein the light removal temperature is 120°C, the pressure is 0.15MPa, and the reflux ratio is 8, and the heavy removal temperature is 120°C, the pressure is 0.1MPa, and the reflux ratio is 9. The high-purity n-hexane is secondary filtered to obtain electronic-grade n-hexane for use. After inspection, the purity of n-hexane is 99.996%, and the water content, particulate matter and metal ions all meet the electronic-grade indicators.

[0039] Example 2

[0040] This embodiment provides a method for preparing electronic grade n-hexane, comprising the following steps:

[0041] Step S1. passing an industrial-grade n-hexane raw material with a n-hexane content greater than 99% into an adsorbent 4A molecular sieve to remove moisture from the n-hexane, wherein the adsorption temperature is 30°C. In order to recycle the adsorbent, the adsorbent is dehydrated at a desorption temperature of 150°C; then a catalytic hydrogenation reaction is performed to obtain crude n-hexane, using a platinum-tin catalyst, and the catalytic reaction temperature is 300°C.

[0042] Step S2. The catalytic hydrogenation material is primary filtered to remove particulate matter, and then the light removal and heavy removal two-stage distillation are performed to obtain high-purity n-hexane, wherein the light removal temperature is 100°C, the pressure is 0.2MPa, and the reflux ratio is 7, and the heavy removal temperature is 100°C, the pressure is 0.1MPa, and the reflux ratio is 7. The high-purity n-hexane is secondary filtered to obtain electronic-grade n-hexane for use. After inspection, the purity of n-hexane is 99.995%, and the water content, particulate matter and metal ions all meet the electronic-grade indicators.

[0043] Example 3

[0044] This embodiment provides a method for preparing electronic grade n-hexane, comprising the following steps:

[0045] Step S1. passing an industrial-grade n-hexane raw material with a n-hexane content greater than 99% into an adsorbent 4A molecular sieve to remove moisture from the n-hexane, wherein the adsorption temperature is 20°C. In order to recycle the adsorbent, the adsorbent is dehydrated at a desorption temperature of 100°C; then a catalytic hydrogenation reaction is performed to obtain crude n-hexane, using a platinum-tin catalyst, and the catalytic reaction temperature is 300°C.

[0046] Step S2. The catalytically hydrogenated material is subjected to primary filtration to remove particulate matter, and then subjected to two-stage distillation for light removal and heavy removal to obtain high-purity n-hexane, wherein the light removal temperature is 150° C., the pressure is 0.19 MPa, and the reflux ratio is 10, and the heavy removal temperature is 80° C., the pressure is 0.15 MPa, and the reflux ratio is 5. The high-purity n-hexane is subjected to secondary filtration to obtain electronic-grade n-hexane for charging and use. After inspection, the purity of the n-hexane is 99.992%, and the water content, particulate matter and metal ions all meet the electronic-grade indicators.

[0047] Example 4

[0048] This embodiment provides a method for preparing electronic grade n-hexane, comprising the following steps:

[0049] Step S1. passing an industrial-grade n-hexane raw material with a n-hexane content greater than 99% into an adsorbent 4A molecular sieve to remove moisture from the n-hexane, wherein the adsorption temperature is 50°C. In order to recycle the adsorbent, the adsorbent is dehydrated at a desorption temperature of 240°C; then a catalytic hydrogenation reaction is performed to obtain crude n-hexane, using a platinum-tin catalyst, and the catalytic reaction temperature is 200°C.

[0050] Step S2. The catalytic hydrogenation material is primary filtered to remove particulate matter, and then the light removal and heavy removal two-stage distillation are performed to obtain high-purity n-hexane, wherein the light removal temperature is 70°C, the pressure is 0.15MPa, and the reflux ratio is 5, and the heavy removal temperature is 160°C, the pressure is 0.12MPa, and the reflux ratio is 10. The high-purity n-hexane is secondary filtered to obtain electronic-grade n-hexane for use. After inspection, the purity of n-hexane is 99.995%, and the water content, particulate matter and metal ions all meet the electronic-grade indicators.

[0051] The above is only a preferred embodiment of the present application and does not constitute any form of limitation to the present application. Although the present application has been disclosed as a preferred embodiment as above, it is not intended to limit the present application. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present application. However, any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for preparing electronic grade n-hexane, characterized in that: The steps include: Step S1. passing the n-hexane raw material into an adsorbent to remove water from the n-hexane, and then performing a catalytic hydrogenation reaction to obtain crude n-hexane; Step S2: primary filtering the catalytically hydrogenated material to remove particulate matter, and then performing two-stage distillation for light and heavy fraction removal to obtain high-purity n-hexane, and secondary filtering the high-purity n-hexane to obtain electronic-grade n-hexane.

2. A method for preparing electronic grade n-hexane according to claim 1, characterized in that: The n-hexane raw material is of industrial grade, and the content of n-hexane is greater than or equal to 99%.

3. A method for preparing electronic grade n-hexane according to claim 1, characterized in that: The adsorbent is 4A grade molecular sieve, and the adsorption temperature is 20-50°C.

4. The method for preparing electronic grade n-hexane according to claim 1, characterized in that: The catalyst for the catalytic hydrogenation reaction is a platinum-tin catalyst, and the temperature of the catalytic reaction is 200-400°C.

5. The method for preparing electronic grade n-hexane according to claim 1, characterized in that: The temperature for light removal is 70-150°C, the reflux ratio is 5-10, the pressure is P1, and the range of P1 is 0.1MPa<P1≤0.2MPa; the temperature for heavy removal is 80-160°C, the reflux ratio is 5-10, the pressure is P2, the range of P2 is 0.1MPa≤P2<0.2MPa, and P2 is less than P1.

6. The device used in the method for preparing electronic grade n-hexane according to any one of claims 1 to 5, characterized in that: It comprises a raw material tank (1), an adsorption tower (2), a catalytic hydrogenation reactor (3), an intermediate tank (6), a light removal tower (7), a heavy removal tower (8) and a product tank (9); The raw material tank (1) is connected to the adsorption tower (2); one end of the adsorption tower (2) away from the raw material tank (1) is connected to the bottom of the catalytic hydrogenation reactor (3); one end of the catalytic hydrogenation reactor (3) away from the adsorption tower (2) is connected to the top of the intermediate tank (6) through a first pipeline (4); the bottom of the intermediate tank (6) is connected to the lower part of the light removal tower (7); the bottom of the light removal tower (7) is connected to the heavy removal tower (8); the upper part of the heavy removal tower (8) is connected to the product tank (9); and the bottom of the product tank (9) is connected to a second pipeline (10).

7. The device for preparing electronic n-hexane according to claim 7, characterized in that: The first pipe (4) is provided with a first filter (5), and the second pipe (10) is provided with a second filter (11). Both the first filter (5) and the second filter (11) are high-density polyethylene filters with a pore size of 0.1 to 2 μm.

8. The device for preparing electronic n-hexane according to claim 7, characterized in that: The de-heavy tower (8), the de-light tower (7) and the product tank (9) are all electrolytically polished or lined with PFA.

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