Preparation method of electronic grade carbon dioxide and device for preparing electronic grade carbon dioxide

Abstract

The invention relates to the field of gas purification, and discloses a preparation method of electronic-grade carbon dioxide and a device for preparing the electronic-grade carbon dioxide. The preparation method comprises the following steps: compressing a gas phase obtained by carrying out gas-liquid separation on epoxy decarburization regeneration gas, then carrying out dealkylation on the obtained compressed gas, and then drying, liquefying and purifying the obtained dealkylation gas to obtain the electronic-grade carbon dioxide, wherein in the epoxy decarburization regeneration gas, the content of total hydrocarbon is less than or equal to 0.7 Vol%, and the content of alkylene oxide is less than or equal to 10ppm; the dealkylation method comprises the step of contacting the pressurized gas with modified activated carbon. Epoxy decarburization regeneration gas is used as raw material gas, the method is used for preparing the electronic grade carbon dioxide, dealkylation by adopting a catalytic oxidation method is avoided, and the energy consumption is greatly reduced under the condition that high-quality electronic grade carbon dioxide is obtained.

Description

Technical Field

[0001] The invention relates to the field of gas purification, and in particular to a method for preparing electronic-grade carbon dioxide and a device for preparing electronic-grade carbon dioxide. Background Art

[0002] With the development of electronic industries such as integrated circuits, optical fibers and semiconductors, the application of electronic grade carbon dioxide is becoming more and more extensive. It is commonly used in oxidation, diffusion, chemical vapor deposition, supercritical cleaning, etc. At present, the carbon dioxide products on the market are mainly industrial grade and food grade, with a purity of 99.0-99.9%. The purity of electronic grade carbon dioxide is relatively high, and it needs to reach more than 99.999%.

[0003] The process of producing carbon dioxide usually adopts the process of pressurization, drying, dehydration and liquefaction. If the hydrocarbon content in the raw gas is high, a catalytic oxidation section needs to be added after pressurization to remove the hydrocarbon. The reaction temperature of the catalytic oxidation section is 300-450℃, and oxygen needs to be introduced, which consumes a lot of energy. In addition, the refrigerant used in the refrigerator of the liquefaction section is ammonia refrigerant and fluorine-containing refrigerant, which is dangerous and harmful to the environment.

[0004] CN109336113A discloses a method for producing ultrapure carbon dioxide. The process includes vaporization, heating, desulfurization, catalytic conversion, adsorption drying, refrigeration and purification of liquid carbon dioxide. The process can produce 99.9995% electronic grade ultrapure carbon dioxide products, wherein the temperature of the catalytic conversion section is 300-500°C, and the energy consumption is relatively high.

[0005] CN109721054A discloses a production method and device, including a dehydrogenation unit, a dehydration unit, a liquefaction unit, a purification unit, etc. The dehydrogenation unit adopts a catalytic oxidation method, and the refrigerant used in the liquefaction unit is liquid ammonia. There are problems such as high energy consumption and the danger of liquid ammonia.

[0006] Therefore, there is an urgent need for a process for preparing electronic-grade carbon dioxide that avoids the use of a high-energy catalytic oxidation method for dehydrogenation when using a raw gas with a high hydrocarbon content to prepare electronic-grade carbon dioxide. Summary of the invention

[0007] The purpose of the present invention is to overcome the problem in the prior art that when raw gas with a high hydrocarbon content is used to prepare electronic-grade carbon dioxide, a catalytic oxidation method with high energy consumption is required for dehydrogenation. A method for preparing electronic-grade carbon dioxide and a device for preparing electronic-grade carbon dioxide are provided. The preparation method uses epoxy decarbonization regeneration gas as raw gas and modified activated carbon as an adsorbent for dehydrogenation, thereby avoiding the use of catalytic oxidation for dehydrogenation. While obtaining high-quality electronic-grade carbon dioxide, energy consumption is greatly reduced.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing electronic-grade carbon dioxide, wherein the preparation method comprises: compressing the gas phase obtained by gas-liquid separation of epoxy decarbonization regeneration gas, then dehydrocarbonizing the obtained compressed gas, and then drying, liquefying and purifying the obtained dehydrocarbonized gas to obtain the electronic-grade carbon dioxide; wherein,

[0009] In the epoxy decarbonization regeneration gas, the content of total hydrocarbons is less than or equal to 0.7 Vol%, and the content of epoxy alkylene is less than or equal to 10 ppm; the dehydrogenation method comprises: contacting the compressed gas with modified activated carbon.

[0010] The second aspect of the present invention provides a device for preparing electronic grade carbon dioxide, wherein the device comprises: a coalescing separator, a compressor, an adsorption tower, a drying tower, a refrigerator and a distillation tower connected in sequence;

[0011] The coalescing separator is used for gas-liquid separation of epoxy decarbonization regeneration gas; the compressor is used for compressing the gas phase obtained by the gas-liquid separation; the adsorption tower is used for dehydrocarbonizing the compressed gas; the drying tower is used for drying the dehydrocarbonized gas obtained by the dehydrocarbonization; the refrigerator is used for liquefying the dried gas; and the distillation tower is used for purifying the liquefied product to obtain electronic grade carbon dioxide.

[0012] Through the above technical solution, the beneficial effects of the present invention are:

[0013] The method for preparing electronic-grade carbon dioxide provided by the present invention comprises gas-liquid separation, compression, dehydrogenation, drying, liquefaction and purification of epoxy decarbonization regeneration gas; wherein modified activated carbon is used as an adsorbent for dehydrogenation. The epoxy decarbonization regeneration gas with a total hydrocarbon content of less than or equal to 0.7 Vol% and an alkylene oxide content of less than or equal to 10 ppm is used as raw gas, and the method is used to prepare electronic-grade carbon dioxide, thereby avoiding the use of catalytic oxidation method for dehydrogenation, and greatly reducing energy consumption while obtaining high-quality electronic-grade carbon dioxide.

[0014] In a preferred embodiment of the present invention, by selecting suitable modified activated carbon, including selecting suitable specific surface area, average particle size, average pore size and porosity of the activated carbon, and suitable type, average particle size and content of loaded metal particles, the modified activated carbon has a good dehydrogenation effect for epoxy decarbonization regeneration gas with a total hydrocarbon content of less than or equal to 0.7 Vol%, and an alkylene oxide content of less than or equal to 10 ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a flow chart of the preparation of electronic grade carbon dioxide in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0016] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0017] The first aspect of the present invention provides a method for preparing electronic grade carbon dioxide, wherein the preparation method comprises: compressing the gas phase obtained by gas-liquid separation of epoxy decarbonization regeneration gas, then dehydrocarbonizing the obtained compressed gas, and then drying, liquefying and purifying the obtained dehydrocarbonized gas to obtain the electronic grade carbon dioxide; wherein,

[0018] In the epoxy decarbonization regeneration gas, the content of total hydrocarbons is less than or equal to 0.7 Vol%, and the content of epoxy alkylene is less than or equal to 10 ppm; the dehydrogenation method comprises: contacting the compressed gas with modified activated carbon.

[0019] The regeneration gas of the decarbonization unit of the epoxy device mainly contains carbon dioxide, and also contains trace amounts of hydrocarbon gases such as methane, ethylene, ethylene oxide, and gases such as hydrogen and oxygen. This part of the gas needs to be removed to meet the requirements of electronic-grade carbon dioxide; in addition, impurities such as moisture in the raw gas must also be removed to meet product requirements. The method for preparing electronic-grade carbon dioxide provided by the present invention includes gas-liquid separation, compression, dehydrogenation, drying, liquefaction and purification of epoxy decarbonization regeneration gas; wherein modified activated carbon is used as an adsorbent for dehydrogenation. The epoxy decarbonization regeneration gas with a total hydrocarbon content of less than or equal to 0.7 Vol% and an alkylene oxide content of less than or equal to 10 ppm is used as the raw gas, and the method is used to prepare electronic-grade carbon dioxide, thereby avoiding the use of catalytic oxidation for dehydrogenation, and greatly reducing energy consumption while obtaining high-quality electronic-grade carbon dioxide.

[0020] According to the present invention, preferably, the modified activated carbon comprises activated carbon and metal particles loaded in the pores of the activated carbon.

[0021] According to the present invention, preferably, the metal particles are selected from copper particles and / or magnesium particles, preferably copper particles and magnesium particles. Using activated carbon loaded with copper particles and magnesium particles as an adsorbent can effectively adsorb hydrocarbon gases.

[0022] According to the present invention, preferably, the specific surface area of ​​the activated carbon is 1000-3000m 2 / g, preferably 1800-2500m 2 / g; the average particle size is 1-5mm, preferably 2-4mm.

[0023] According to the present invention, preferably, the activated carbon has an average pore size of 3-30 nm, preferably 25-30 nm; a porosity of 0.7-0.9 cm 3 / g, preferably 0.8-0.9cm 3 / g.

[0024] According to the present invention, preferably, in the modified activated carbon, the average particle size of the copper particles is 3-10 nm, and the average particle size of the magnesium particles is 5-20 nm.

[0025] The modified activated carbon made from activated carbon, copper particles and magnesium particles that meet the above conditions can effectively adsorb hydrocarbon gases.

[0026] According to the present invention, preferably, based on the total weight of the modified activated carbon, the contents of the copper particles and the magnesium particles in the modified activated carbon are 0.8-1.5wt% and 0.3-0.9wt%, respectively. The contents of the copper particles and the magnesium particles in the modified activated carbon meet this range, so that the total hydrocarbons in the raw gas can be effectively adsorbed, otherwise it will lead to insufficient adsorption of the total hydrocarbons.

[0027] In order to achieve better effects of dehydrogenation, drying, liquefaction and purification, the gas obtained by gas-liquid separation of epoxy decarbonization regeneration gas is compressed before dehydrogenation. According to the present invention, preferably, the compression method includes: pressurizing the gas phase obtained by gas-liquid separation to 2.3-3MPa.

[0028] According to the present invention, preferably, in the dehydrogenation process, based on the total volume of the epoxy decarbonization regeneration gas being 1 L, the amount of the modified activated carbon used is 30-60 g.

[0029] According to the present invention, preferably, the dehydrocarbonization process comprises: contacting the compressed gas with the modified activated carbon at 35-45° C. for 10-30 min.

[0030] According to the present invention, preferably, the content of total hydrocarbons in the dehydrocarbonized gas is less than or equal to 2 ppm.

[0031] According to the present invention, preferably, the drying method comprises: contacting the dehydrocarbon gas with a molecular sieve.

[0032] According to the present invention, preferably, the molecular sieve has pores with an average pore size of 0.3-0.5 nm; for example, it can be selected from at least one of 3A molecular sieve, 4A molecular sieve and 5A molecular sieve.

[0033] According to the present invention, preferably, based on the total volume of the epoxy decarbonization regeneration gas being 1 L, the amount of the molecular sieve used is 30-60 g.

[0034] According to the present invention, preferably, the drying conditions include: contacting the dehydrocarbon gas with the molecular sieve at 20-40° C. for 10-30 min.

[0035] According to the present invention, preferably, the water content in the dry gas obtained by drying is below 3 ppm.

[0036] In the present invention, ppm is based on volume.

[0037] According to the present invention, preferably, the liquefaction conditions include: the refrigeration medium is carbon dioxide, and the refrigeration temperature is -25° C. to -10° C. Compared with conventional ammonia refrigerants and fluorine-containing refrigerants, using carbon dioxide as the refrigeration medium has a better refrigeration effect and a safer preparation process.

[0038] According to the present invention, preferably, the purification method comprises: distilling the liquefied product obtained by the liquefaction.

[0039] According to the present invention, preferably, the distillation conditions include: temperature of -22°C to -15°C, and pressure of 1.5-2.1 MPa.

[0040] The second aspect of the present invention provides a device for preparing electronic grade carbon dioxide, wherein the device comprises: a coalescing separator, a compressor, an adsorption tower, a drying tower, a refrigerator and a distillation tower connected in sequence;

[0041] The coalescing separator is used for gas-liquid separation of epoxy decarbonization regeneration gas; the compressor is used for compressing the gas phase obtained by the gas-liquid separation; the adsorption tower is used for dehydrocarbonizing the compressed gas; the drying tower is used for drying the dehydrocarbonized gas obtained by the dehydrocarbonization; the refrigerator is used for liquefying the dried gas; and the distillation tower is used for purifying the liquefied product to obtain electronic grade carbon dioxide.

[0042] According to the present invention, preferably, the adsorption tower is filled with modified activated carbon.

[0043] According to the present invention, preferably, the drying tower is filled with molecular sieves.

[0044] In the device for preparing electronic-grade carbon dioxide in the second aspect of the present invention, the modified activated carbon and the molecular sieve are exactly the same as those in the method for preparing electronic-grade carbon dioxide described in the first aspect of the present invention. In order to avoid repetition, the present invention will not be described in detail in the second aspect, and those skilled in the art should not understand it as a limitation of the present invention.

[0045] According to the present invention, preferably, the device comprises two groups of adsorption towers and two groups of drying towers. Two groups of adsorption towers are provided, one group of adsorption towers is used for adsorption, and the modified activated carbon in the other group of adsorption towers is regenerated and cold-blown after use, and the two groups of adsorption towers are used alternately, and nitrogen is used as the regeneration and cold-blowing medium. Two drying towers are provided, one drying tower is used for drying, and the molecular sieve in the other drying tower is regenerated and cold-blown after use, and the two towers are operated alternately, and air is used as the regeneration and cold-blowing medium.

[0046] According to the present invention, preferably, the filtration accuracy of the filter element in the coalescing separator is 0.1-1 μm.

[0047] According to the present invention, preferably, the distillation tower is connected to the adsorption tower and the drying tower respectively, and the gas phase flowing out of the distillation tower is mixed with the dehydrocarbonized gas flowing out of the adsorption tower and then enters the drying tower, so that the gas phase flowing out of the top of the distillation tower is heat exchanged with the dehydrocarbonized gas entering the drying tower, thereby reducing the moisture entering the drying tower.

[0048] According to a preferred embodiment of the present invention, Figure 1 The method for preparing electronic grade carbon dioxide in the device provided by the present invention comprises the following steps:

[0049] The epoxy decarbonization regeneration gas first passes through a coalescing separator for gas-liquid separation to separate the tiny impurities contained therein, and then the gas phase flowing out of the coalescing separator enters a compressor for pressurization to 2.3-3MPa. The obtained compressed gas is cooled to 35-45°C and then enters an adsorption tower (two groups of adsorption towers are set up, one group of adsorption towers is used for adsorption, and the modified activated carbon in the other group of adsorption towers is used for regeneration and cold blowing. The two groups of adsorption towers are used alternately, and nitrogen is used as the regeneration and cold blowing medium), and the residence time is 10-30min; the adsorption tower is filled with modified activated carbon (based on the total volume of the epoxy decarbonization regeneration gas being 1L, the amount of the modified activated carbon is 30-60g), and the hydrocarbon substances contained therein are removed to less than or equal to 2ppm. Then the obtained dehydrocarbonized gas enters the dehydration and drying section, and is dehydrated in a drying tower (two drying towers are set, one drying tower is used for drying, and the molecular sieve in the other drying tower is regenerated and cold-blown after use, and the two towers are operated alternately, and the regeneration and cold-blowing medium is air) at 20-40°C, and the residence time is 10-30min; the drying tower is filled with molecular sieves (the total volume of the epoxy decarbonization regeneration gas is 1L, and the amount of the molecular sieve is 30-60g), and the water content is reduced to below 3ppm. The dry gas enters the carbon dioxide refrigerator and is liquefied at a refrigeration temperature of -25°C to -10°C. The liquefied product is introduced into the distillation tower and purified at a temperature of -22°C to -15°C and a pressure of 1.5-2.1MPa. The liquid coming out of the bottom of the distillation tower is the electronic grade carbon dioxide product. The gas phase flowing out of the top of the distillation tower exchanges heat with the dehydrocarbonized gas entering the drying tower.

[0050] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, all methods are conventional methods; and the reagents and materials used, unless otherwise specified, can be obtained from commercial sources.

[0051] The composition and purity of the carbon dioxide product are determined according to the determination method in GB / T23938-2021 High-purity Carbon Dioxide.

[0052] The following examples are used to illustrate the preparation of electronic grade carbon dioxide

[0053] Examples 1-8

[0054] The composition of the epoxy decarburization regeneration gas in Examples 1-8 is shown in Table 1.

[0055] Follow these steps to prepare electronic grade carbon dioxide:

[0056] The epoxy decarbonization regeneration gas first passes through the coalescing separator for gas-liquid separation (the filtration accuracy of the filter element is 1μm) to separate the tiny impurities contained therein, and then the gas phase flowing out of the coalescing separator enters the compressor for pressurization to 2.8MPa. The compressed gas obtained is cooled to 40°C and then enters the adsorption tower (two groups of adsorption towers are set up, one group of adsorption towers is used for adsorption, and the modified activated carbon in the other group of adsorption towers is regenerated and cold-blown after use. The two groups of adsorption towers are used alternately, and nitrogen is used as the regeneration and cold-blowing medium), and the residence time is 30min; the adsorption tower is filled with modified activated carbon (based on the total volume of epoxy decarbonization regeneration gas being 1L, the amount of modified activated carbon is 60g), and the hydrocarbon substances contained therein are removed to 2ppm. Then the obtained dehydrocarbonized gas enters the dehydration and drying section, and is dehydrated in a drying tower at a temperature of 35°C (two drying towers are set up, one drying tower is used for drying, and the molecular sieve in the other drying tower is regenerated and cold-blown after use, and the two towers are operated alternately, and the regeneration and cold-blowing medium is air).

[0057] The residence time is 30 minutes; the drying tower is filled with 3A molecular sieve (based on the total volume of epoxy decarbonization regeneration gas of 1L, the amount of molecular sieve is 50g) to reduce the water content to below 3ppm. The drying gas enters the carbon dioxide refrigerator and is liquefied at a refrigeration temperature of -25℃. The liquefied product is introduced into the distillation tower and purified under the conditions of a pressure of 1.9MPa and a temperature of -15℃. The liquid coming out of the bottom of the distillation tower is the electronic grade carbon dioxide product. The gas phase flowing out of the top of the distillation tower exchanges heat with the dehydrocarbonized gas entering the drying tower.

[0058] The modified activated carbon is activated carbon loaded with copper particles and magnesium particles; based on the total weight of the modified activated carbon, the contents of the copper particles and the magnesium particles in the modified activated carbon are 1wt% and 0.7wt% respectively;

[0059] The specific surface area of ​​activated carbon is 2000m 2 / g, average particle size is 3mm, average pore size is 30nm, and porosity is 0.8cm 3 / g; the average particle size of the copper particles is 6nm, and the average particle size of the magnesium particles is 15nm.

[0060] Example 9

[0061] Electronic grade carbon dioxide was prepared according to the method of Example 1, except that the specific surface area and average particle size of the activated carbon in the modified activated carbon were different. The specific surface area of ​​the activated carbon was 1500 m 2 / g, with an average particle size of 5mm. Electronic grade carbon dioxide products were obtained.

[0062] Example 10

[0063] Electronic grade carbon dioxide was prepared according to the method of Example 1, except that the average pore size and porosity of the activated carbon in the modified activated carbon were different. The average pore size of the activated carbon was 20 nm and the porosity was 0.7 cm 3 / g. Electronic grade carbon dioxide product is obtained.

[0064] Embodiment 11

[0065] Electronic grade carbon dioxide was prepared according to the method of Example 1, except that the modified activated carbon was different and iron particles were also loaded on the activated carbon. Specifically, the modified activated carbon was activated carbon loaded with copper particles, magnesium particles and iron particles; the average particle size of the iron particles was 30 nm; based on the total weight of the modified activated carbon, the contents of copper particles, magnesium particles and iron particles in the modified activated carbon were 1wt%, 0.7wt% and 0.3wt%, respectively. An electronic grade carbon dioxide product was obtained.

[0066] Example 12

[0067] Electronic grade carbon dioxide was prepared according to the method of Example 1, except that the modified activated carbon was different, and only copper particles were loaded on the activated carbon. Specifically, the modified activated carbon was activated carbon loaded with copper particles; based on the total weight of the modified activated carbon, the content of copper particles in the modified activated carbon was 1.7 wt %. To obtain an electronic grade carbon dioxide product.

[0068] Example 13

[0069] Electronic grade carbon dioxide was prepared according to the method of Example 1, except that the modified activated carbon was different, and copper particles of equal weight and average particle size were replaced with iron particles to obtain an electronic grade carbon dioxide product.

[0070] Embodiment 14

[0071] Electronic grade carbon dioxide was prepared according to the method of Example 1, except that the contents of copper particles and magnesium particles in the modified activated carbon were different. Specifically, based on the total weight of the modified activated carbon, the contents of copper particles and magnesium particles in the modified activated carbon were 0.5wt% and 0.2wt%, respectively. Electronic grade carbon dioxide product was obtained.

[0072] Embodiment 15

[0073] Electronic grade carbon dioxide was prepared according to the method of Example 1, except that the average particle sizes of the copper particles and the magnesium particles in the modified activated carbon were different, the average particle size of the copper particles was 12 nm, and the average particle size of the magnesium particles was 26 nm, to obtain an electronic grade carbon dioxide product.

[0074] Comparative Example 1

[0075] The carbon dioxide product was prepared according to the method of Example 1, except that a carbon dioxide having a specific surface area of ​​2000 m 2 / g, average particle size is 3mm, average pore size is 30nm, and porosity is 0.8cm 3 / g of activated carbon replaces the same weight of modified activated carbon to obtain carbon dioxide product.

[0076] Comparative Example 2

[0077] The carbon dioxide product was prepared according to the method of Example 1, except that the composition of the epoxy decarburization regeneration gas was different. The composition of the epoxy decarburization regeneration gas is shown in Table 1. A carbon dioxide product was obtained.

[0078] Test Case

[0079] The composition of the epoxy decarbonization regeneration gas used in each embodiment and comparative example and the composition and purity parameters of the obtained carbon dioxide product are shown in Table 1.

[0080] Table 1

[0081]

[0082] It can be seen from the results in Table 1 that the carbon dioxide products prepared by the method of the present invention in Examples 1-15 can all meet the standards of electronic grade carbon dioxide. While Comparative Example 1 uses activated carbon without metal particles in the pores for dehydrogenation, and the total hydrocarbon and alkylene oxide contents of the epoxy decarbonization regeneration gas raw material used in Comparative Example 2 exceed the standard. Although the carbon dioxide purity of the obtained carbon dioxide product reaches more than 99.999%, the total hydrocarbon content in the product exceeds the standard, and an electronic grade carbon dioxide product cannot be obtained. This shows that the method of the present invention is used to dehydrogenate with modified activated carbon, and the epoxy decarbonization regeneration gas with a total hydrocarbon content of less than or equal to 0.7 Vol%, and an alkylene oxide content of less than or equal to 10 ppm, has a good dehydrogenation effect, thereby obtaining high-quality electronic grade carbon dioxide.

[0083] In addition, Example 9 changed the specific surface area and average particle size of the activated carbon in the modified activated carbon, Example 10 changed the average pore size and porosity of the activated carbon in the modified activated carbon, Examples 11-13 all changed the types of metal particles loaded on the modified activated carbon, Example 14 changed the content of copper particles and magnesium particles in the modified activated carbon, and Example 15 changed the average particle size of copper particles and magnesium particles in the modified activated carbon. Although the obtained carbon dioxide products all met the electronic grade standard, the total hydrocarbon content increased compared with Example 1. This shows that the performance of the activated carbon in the modified activated carbon, the type, content and average particle size of the loaded metal particles all affect the dehydrocarbon effect.

[0084] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing electronic grade carbon dioxide, characterized in that: The preparation method comprises: compressing the gas phase obtained by gas-liquid separation of epoxy decarbonization regeneration gas, then dehydrocarbonizing the obtained compressed gas, and then drying, liquefying and purifying the obtained dehydrocarbonized gas to obtain the electronic grade carbon dioxide; wherein, In the epoxy decarbonization regeneration gas, the content of total hydrocarbons is less than or equal to 0.7 Vol%, and the content of epoxy alkylene is less than or equal to 10 ppm; the dehydrogenation method comprises: contacting the compressed gas with modified activated carbon.

2. The preparation method according to claim 1, characterized in that: The modified activated carbon includes activated carbon and metal particles loaded in the pores of the activated carbon; Preferably, the metal particles are selected from copper particles and / or magnesium particles, preferably copper particles and magnesium particles; Preferably, the specific surface area of ​​the activated carbon is 1000-3000m 2 / g, preferably 1800-2500m 2 / g; the average particle size is 1-5mm, preferably 2-4mm; Preferably, the activated carbon has an average pore size of 3-30 nm, preferably 25-30 nm; a porosity of 0.7-0.9 cm 3 / g, preferably 0.8-0.9cm 3 / g; Preferably, in the modified activated carbon, the average particle size of the copper particles is 3-10 nm, and the average particle size of the magnesium particles is 5-20 nm; Preferably, based on the total weight of the modified activated carbon, the contents of the copper particles and the magnesium particles in the modified activated carbon are 0.8-1.5 wt % and 0.3-0.9 wt %, respectively.

3. The preparation method according to claim 1 or 2, characterized in that: The compression method comprises: pressurizing the gas phase obtained by gas-liquid separation to 2.3-3 MPa; Preferably, in the dehydrogenation process, the amount of the modified activated carbon is 30-60 g based on the total volume of the epoxy decarbonization regeneration gas being 1 L; Preferably, the dehydrocarbonization process comprises: contacting the compressed gas with the modified activated carbon at 35-45° C. for 10-30 min.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The drying method comprises: contacting the dehydrocarbon gas with a molecular sieve; Preferably, the molecular sieve has pores with an average pore size of 0.3-0.5 nm.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The liquefaction conditions include: the refrigeration medium is carbon dioxide, and the refrigeration temperature is -25°C to -10°C.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The purification method comprises: rectifying the liquefied product obtained by liquefaction; Preferably, the distillation conditions include: temperature of -22°C to -15°C and pressure of 1.5-2.1 MPa.

7. A device for preparing electronic grade carbon dioxide, characterized in that: The device comprises: a coalescing separator, a compressor, an adsorption tower, a drying tower, a refrigerator and a distillation tower which are connected in sequence; The coalescing separator is used for gas-liquid separation of epoxy decarbonization regeneration gas; the compressor is used for compressing the gas phase obtained by the gas-liquid separation; the adsorption tower is used for dehydrocarbonizing the compressed gas; the drying tower is used for drying the dehydrocarbonized gas obtained by the dehydrocarbonization; the refrigerator is used for liquefying the dried gas; and the distillation tower is used for purifying the liquefied product to obtain electronic grade carbon dioxide.

8. The device according to claim 7, characterized in that The adsorption tower is filled with modified activated carbon; Preferably, the drying tower is filled with molecular sieves; Preferably, the device comprises two groups of adsorption towers and two groups of drying towers.

9. The device according to claim 7 or 8, characterized in that The filtration accuracy of the filter element in the coalescing separator is 0.1-1 μm.

10. The device according to any one of claims 7 to 9, characterized in that: The distillation tower is connected to the adsorption tower and the drying tower respectively, and the gas phase flowing out of the distillation tower is mixed with the dehydrocarbonized gas flowing out of the adsorption tower and then enters the drying tower.

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