Method and device for removing carbon dioxide from carbonyl fluoride

Abstract

The present application relates to the field of gas impurity removal, and more specifically, to a method and apparatus for removing carbon dioxide from carbonyl fluoride. The method comprises the following steps: 1. preheating; 2. fluidized bed separation; 3. primary gas-solid separation; and 4. secondary gas-solid separation. The apparatus comprises a preheating device, a gas-solid fluidized bed reactor, a primary cyclone separator, and a secondary cyclone separator, which are connected in sequence. The present application utilizes sodium methoxide solid particles to react and separate carbon dioxide from carbonyl fluoride to obtain sodium methyl carbonate solid. The carbonyl fluoride and solid particles are further separated via subsequent primary cyclone separators and secondary cyclone separators. The residual sodium methoxide solid particles and the generated sodium methyl carbonate can be recovered. The reaction process is green and pollution-free, effectively remedying the lack of safety in removing carbon dioxide from carbonyl fluoride in existing technologies.

Description

Technical Field

[0001] The present application relates to the field of gas impurity removal, and more specifically, to a method and apparatus for removing carbon dioxide from carbonyl fluoride. Background Art

[0002] Carbonyl fluoride (COF2) is an important gas used for semiconductor etching and semiconductor cleaning. With the rapid development of the semiconductor industry, carbonyl fluoride has also become widely concerned. In semiconductor manufacturing equipment and liquid crystal manufacturing processes, perfluorocarbons (PFCs) or nitrogen trifluoride (NF3) are usually used as conventional etching gases and cleaning gases. However, perfluorocarbons and nitrogen trifluoride are both greenhouse gases and have an additive effect on the greenhouse effect. Compared with the above two traditional semiconductor industry gases, carbonyl fluoride exists in the atmosphere for a shorter time. Even if carbonyl fluoride decomposes to produce carbon dioxide, its aggravating effect on the greenhouse effect is far less than that of traditional semiconductor industry gases such as perfluorocarbons and nitrogen trifluoride. Therefore, carbonyl fluoride is a more environmentally friendly semiconductor gas.

[0003] Due to its inherent properties, carbonyl fluoride (CF) always contains carbon dioxide during its production. At atmospheric pressure, the boiling point of CF is -84.57°C, while that of carbon dioxide is -78°C. These close boiling points make it difficult to separate CO2 from CF via conventional distillation. Furthermore, the purity of CF directly impacts the efficiency and quality of its semiconductor etching and cleaning applications. Therefore, removing CO2 from the crude CF product is a key issue in CF purification.

[0004] Currently, there is little research on removing carbon dioxide from carbonyl fluoride. Research on the purification of crude carbonyl fluoride products has primarily focused on azeotropic and extractive distillation of carbonyl fluoride, such as the azeotropic distillation system proposed in Chinese invention patent application publication number CN112279234A. However, both azeotropic and extractive distillation methods result in complex and lengthy processes for producing high-purity carbonyl fluoride. Chinese invention patent application publication number CN103213965A proposes reacting the crude carbonyl fluoride product with ClF, ClF3, or ClF5 to convert the carbon dioxide in the carbonyl fluoride into a substance that is easily removed using conventional distillation. However, ClF, ClF3, or ClF5 are highly toxic and corrosive, posing serious safety risks during use.

[0005] In view of the above reasons, it is very necessary to develop a method that can safely and efficiently remove carbon dioxide from carbonyl fluoride. Summary of the Invention

[0006] In order to make up for the shortcomings of existing methods for removing carbon dioxide from carbonyl fluoride, the present application provides a method and equipment for removing carbon dioxide from carbonyl fluoride.

[0007] In a first aspect, the present application provides a method for removing carbon dioxide from carbonyl fluoride, using the following technical solution:

[0008] A method for removing carbon dioxide from carbonyl fluoride comprises the following steps:

[0009] 1. Preheating

[0010] Preheating the carbonyl fluoride mixed gas with carbon dioxide to a reaction temperature to obtain a mixed gas 1;

[0011] 2. Fluidized bed separation

[0012] Using sodium methoxide solid particle impurity remover to perform fluidized bed separation on mixed gas 1 to remove carbon dioxide and obtain mixed gas 2;

[0013] 3. Primary gas-solid separation

[0014] The mixed gas 2 after fluidized bed separation is subjected to a first-level gas-solid separation to remove particles with a particle size greater than 250 μm; after the separation is completed, a mixed gas 3 is obtained;

[0015] 4. Secondary gas-solid separation

[0016] The mixed gas is subjected to a second-stage gas-solid separation to remove particles with a diameter greater than 10 μm, thereby obtaining carbonyl fluoride with carbon dioxide and granular powder removed.

[0017] In one feasible embodiment, in step 2, the preparation method of sodium methoxide solid particle impurity remover comprises the following steps:

[0018] S1, dissolving povidone in ethanol to form a povidone ethanol solution with a mass concentration of 0.5% to obtain an adhesive;

[0019] S2, placing sodium methoxide and a binder in a granulator to granulate;

[0020] S3. After granulation, the mixture is dried at 40° C. and passed through a 40-60 mesh sieve to obtain the sodium methoxide solid particle impurity remover.

[0021] In one feasible embodiment, the reaction temperature in step 1 is 90-120°C.

[0022] In a second aspect, the present application provides a device for removing carbon dioxide from carbonyl fluoride, which adopts the following technical solution:

[0023] An apparatus for removing carbon dioxide from carbonyl fluoride comprises a preheating device, a gas-solid fluidized bed reactor, a primary cyclone separator, and a secondary cyclone separator connected in sequence;

[0024] Preheating device: used to implement the preheating process in step 1;

[0025] Gas-solid fluidized bed reactor: It is filled with sodium methoxide solid particle impurity remover, the bottom is connected to the preheating device through a pipeline, and the top is connected to the top of the first-stage cyclone separator;

[0026] First-stage cyclone separator: The bottom is connected to the gas-solid fluidized bed; the critical particle size of separation is 250μm;

[0027] Secondary cyclone separator: The critical particle size for separation is 10 μm, and an ash hopper is provided at the bottom.

[0028] In an implementable specific scheme, the operating temperature of the gas-solid fluidized bed reactor is 90-120°C, the operating pressure is atmospheric pressure, the inlet gas velocity is 0.43-0.1 m / s, the critical fluidization velocity is 0.067 m / s, and the carry-out velocity is 0.78 m / s.

[0029] This application has the following beneficial effects:

[0030] The present application utilizes sodium methoxide solid particle impurity remover to react and separate carbon dioxide from carbonyl fluoride to obtain sodium carbonate methyl ester, and further separates the mixed gas and solid particles through subsequent primary cyclone separators and secondary cyclone separators. The sodium methoxide solid particles remaining in the reaction and the sodium carbonate methyl ester generated by the reaction can be recovered, and the reaction process is green and pollution-free, which properly makes up for the defect of insufficient safety of removing carbon dioxide from carbonyl fluoride in the existing technology.

[0031] The purity of the carbonyl fluoride obtained by the separation method of the present application can reach above 99.99% after conventional distillation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of the method provided in this application.

[0033] Explanation of reference numerals: R101 represents a gas-solid fluidized bed reactor; S101 represents a primary cyclone separator; S102 represents a secondary cyclone separator; M101 represents a preheating device;

[0034] 1 represents the flow direction of carbonyl fluoride gas containing carbon dioxide; 2 represents the flow direction of mixed gas one; 3 represents the flow direction of mixed gas two obtained after the reaction with sodium methoxide solid particles; 4 represents the outlet gas direction of the first-stage cyclone separator; 5 represents the outlet gas direction of the second-stage cyclone separator; 6 represents the flow direction of the solid particles separated by the first-stage cyclone separator. DETAILED DESCRIPTION

[0035] The following combination Figure 1 The present application is further described in detail with reference to the accompanying drawings and examples.

[0036] Preparation Example of Sodium Methanol Solid Granule Impurity Remover

[0037] S1, dissolving povidone K-30 in ethanol to obtain a 0.5% povidone ethanol solution as a binder;

[0038] S2, placing sodium methoxide and a binder in a granulator to granulate;

[0039] S3. After granulation, the mixture is dried at 40° C. and passed through a 40-60 mesh sieve to obtain the sodium methoxide solid particle impurity remover.

[0040] Example

[0041] Example 1

[0042] This embodiment provides a device for removing carbon dioxide from carbonyl fluoride. Figure 1 As shown, the equipment includes a preheating device M101, a gas-solid fluidized bed reactor R101, a primary cyclone separator S101, and a secondary cyclone separator S102 which are connected in sequence.

[0043] Among them, the preheating device M101 is used to heat the gas to the reaction temperature; the gas-solid fluidized bed reactor R101 is filled with sodium methoxide solid particle impurity remover, the bottom of which is connected to the preheating device M101 through a pipeline, and the top is connected to the top of the first-stage cyclone separator S101; the bottom of the first-stage cyclone separator S101 is connected to the gas-solid fluidized bed; the critical particle size for separation is 250μm; the critical particle size for separation of the second-stage cyclone separator S102 is 10μm, and an ash hopper is provided at the bottom.

[0044] Example 2

[0045] Based on the equipment provided in Example 1, this embodiment provides a method for removing carbon dioxide from carbonyl fluoride, comprising the following steps:

[0046] A mixed gas of 3.3 kg / hr with a molar composition of 94.7% COF2, 5% CO2 and 0.3% non-carbon dioxide impurities (including one or more of HCl, HF, COCl2, CF4, CO, O2, and N2) is heated to 90°C by a preheating device M101 and then enters a gas-solid fluidized bed reactor R101. The operating temperature of the gas-solid fluidized bed reactor R101 is 90°C, the operating pressure is 101 kPa, the gas velocity at the inlet of the gas-solid fluidized bed reactor R101 is 0.1 m / s, and the critical fluidization velocity u mf is 0.067m / s, and the carrying speed u t The operating range of the gas-solid fluidized bed reactor R101 is 0.78 m / s. mf / u tThe mixed gas undergoes dispersed fluidization in the gas-solid fluidization reactor. The gas after the reaction is passed through a two-stage cyclone separator to remove the particulate powder therein. The critical particle size for separation by the first-stage cyclone separator S101 is 250 μm, and the outlet of the bottom dust particles leads to the bottom layer of the gas-solid fluidized bed reactor R101. The first-stage cyclone separator S101 separates particles with a particle size greater than 250 μm, and the separated particles are sent back to the gas-solid fluidized bed reactor R101 through a pipeline; the top gas separated by the first-stage cyclone separator S101 enters the second-stage cyclone separator S102, and the critical particle size for separation by the second-stage cyclone separator S102 is 10 μm, and an ash hopper is connected to the bottom; the second-stage cyclone separator S102 allows particles with a particle size greater than 10 μm to settle in the ash hopper, and the top gas separated by the second-stage separator enters the distillation equipment. The distillation of non-carbon dioxide gas impurities here is an existing relatively mature technology. This embodiment aims to propose a method for removing carbon dioxide from carbonyl fluoride, and the distillation is not described in detail here. Gas chromatography determined that the molar purity of carbonyl fluoride in the purified mixed gas was 99.999%, the carbon dioxide content was 0.0004%, the sum of the contents of non-carbon dioxide impurities was less than 0.0006%, and the carbon dioxide removal rate was 99.992%.

[0047] The gas-solid fluidized bed reactor R101 is filled with sodium methoxide solid particle impurity remover, which is prepared in Preparation Example.

[0048] Example 3

[0049] Based on the equipment provided in Example 1, this embodiment provides a method for removing carbon dioxide from carbonyl fluoride, comprising the following steps:

[0050] A mixed gas of 14.6 kg / hr molar composition of 94.3% COF2, 5% CO2, and 0.7% non-carbon dioxide impurities (including one or more of HCl, HF, COCl2, CF4, CO, O2, and N2) is heated to 110°C by a preheating device M101 and then enters a gas-solid fluidized bed reactor R101. The operating temperature of the gas-solid fluidized bed reactor R101 is 110°C, the operating pressure is 101 kPa, the gas velocity at the inlet of the gas-solid fluidized bed reactor R101 is 0.43 m / s, and the critical fluidization velocity u mf is 0.067m / s, and the carrying speed u t The operating range of the gas-solid fluidized bed reactor R101 is 0.78 m / s. mf / u tThe mixed gas undergoes dispersed fluidization in the gas-solid fluidization reactor. The gas after the reaction is passed through a two-stage cyclone separator to remove the particulate powder therein. The critical particle size separated by the first-stage cyclone separator S101 is 250μm, and the outlet of the bottom dust particles leads to the bottom layer of the gas-solid fluidized bed reactor R101. The first-stage cyclone separator S101 separates particles with a particle size greater than 250μm, and the separated particles are sent back to the gas-solid fluidized bed reactor R101 through a pipeline; the top gas separated by the first-stage cyclone separator S101 enters the second-stage cyclone separator S102, and the critical particle size separated by the second-stage cyclone separator S102 is 10μm, and an ash hopper is connected to the bottom; the second-stage cyclone separator S102 allows particles with a particle size greater than 10μm to settle in the ash hopper, and the top gas separated by the second-stage separator enters the subsequent distillation equipment. The distillation of non-carbon dioxide gas here is an existing relatively mature technology. This embodiment aims to propose a method for removing carbon dioxide from carbonyl fluoride, and the distillation is not described in detail here. Gas chromatography determined that the molar purity of carbonyl fluoride in the purified mixed gas was 99.999%, the carbon dioxide content was 0.0002%, the total content of non-carbon dioxide impurities was 0.0008%, and the carbon dioxide removal rate was 99.996%.

[0051] The gas-solid fluidized bed reactor R101 is filled with sodium methoxide solid particle impurity remover, which is prepared in Preparation Example.

[0052] Example 4

[0053] Based on the equipment provided in Example 1, this embodiment provides a method for removing carbon dioxide from carbonyl fluoride, comprising the following steps:

[0054] A mixed gas of 25 kg / hr molar composition of 94.5% COF2, 5% CO2 and 0.5% (103 ppm) of non-carbon dioxide impurities (including one or more of HCl, HF, COCl2, CF4, CO, O2, and N2) is heated to 120°C by a preheating device M101 and then enters a gas-solid fluidized bed reactor R101. The operating temperature of the gas-solid fluidized bed reactor R101 is 120°C, the operating pressure is 101 kPa, the gas velocity at the inlet of the gas-solid fluidized bed reactor R101 is 0.78 m / s, and the critical fluidization velocity u mf is 0.067m / s, and the carrying speed u t The operating range of the gas-solid fluidized bed reactor R101 is 0.78 m / s. mf / u tThe mixed gas undergoes dispersed fluidization in the gas-solid fluidization reactor. The gas after the reaction is passed through a two-stage cyclone separator to remove the particulate powder therein. The critical particle size separated by the first-stage cyclone separator S101 is 250μm, and the outlet of the bottom dust particles leads to the bottom layer of the gas-solid fluidized bed reactor R101. The first-stage cyclone separator S101 separates particles with a particle size greater than 250μm, and the separated particles are sent back to the gas-solid fluidized bed reactor R101 through a pipeline; the top gas separated by the first-stage cyclone separator S101 enters the second-stage cyclone separator S102, and the critical particle size separated by the second-stage cyclone separator S102 is 10μm, and an ash hopper is connected to the bottom; the second-stage cyclone separator S102 allows particles with a particle size greater than 10μm to settle in the ash hopper, and the top gas separated by the second-stage separator enters the subsequent distillation equipment. The distillation of non-carbon dioxide gas here is an existing relatively mature technology. This embodiment aims to propose a method for removing carbon dioxide from carbonyl fluoride, and the distillation is not described in detail here. Gas chromatography determined that the molar purity of carbonyl fluoride in the purified mixed gas was 99.990%, the carbon dioxide content was 0.0005%, the total content of non-carbon dioxide impurities was 0.0095%, and the carbon dioxide removal rate was 99.990%.

[0055] The gas-solid fluidized bed reactor R101 is filled with sodium methoxide solid particle impurity remover, which is prepared in Preparation Example.

[0056] Result analysis:

[0057] This application uses sodium methoxide solid particles to absorb carbon dioxide in carbonyl fluoride. The reaction equation is as follows:

[0058] CH3ONa+CO2=C2H3O3Na

[0059] The sodium carbonate methyl ester produced by the reaction is a solid powder at the above reaction temperature and will not be mixed into the carbonyl fluoride gas to cause secondary pollution.

[0060] After being heated to the reaction temperature in a preheating device M101, the carbonyl fluoride gas mixed with carbon dioxide enters a gas-solid fluidized bed reactor R101 containing sodium methoxide solid particles as an impurity remover. Sodium methyl carbonate and other byproducts may accumulate in the gas-solid fluidized bed reactor R101. Furthermore, the sodium methoxide solid particles are consumed as the reaction proceeds, resulting in a decrease in carbon dioxide removal efficiency. Therefore, the sodium methoxide solid particles in the gas-solid fluidized bed reactor R101 need to be regularly replaced. The replaced, smaller sodium methoxide solid particles react with water to produce methanol and sodium hydroxide, enabling complete recovery and material reuse. The resulting sodium methyl carbonate is a solid powder at the reaction temperature and deposits on the sodium methoxide solid particles. During the recovery of the sodium methoxide solid particles, the sodium methyl carbonate reacts with water to produce methanol and sodium bicarbonate, which in turn reacts with sodium hydroxide to produce sodium carbonate and water. Povidone, an auxiliary additive in the formation of the sodium methoxide solid particles, also becomes free during the dissolution of the sodium methoxide particles in water, enabling material recovery without generating any pollution.

[0061] After dispersed fluidization in gas-solid fluidized bed reactor R101, the gas enters a two-stage cyclone separator. The mixed gas from this reactor carries with it some bed particles, primarily sodium methoxide particles sized between 250 and 380 μm. The primary cyclone separator S101 primarily separates sodium methoxide particles larger than 250 μm. After separation, the mixed gas enters the secondary cyclone separator S102, which further separates solid particles larger than 10 μm, such as small sodium methoxide particles, and a small amount of generated sodium methyl carbonate. After passing through the two-stage cyclone separator, the mixed gas enters a standard distillation purification step. The purity of the carbonyl fluoride after distillation can reach over 99.99%.

[0062] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for removing carbon dioxide from carbonyl fluoride, characterized in that: The steps include:

1. Preheating Preheating the carbonyl fluoride mixed gas with carbon dioxide to a reaction temperature to obtain a mixed gas 1; 2. Fluidized bed separation Using sodium methoxide solid particle impurity remover to perform fluidized bed separation on mixed gas 1 to remove carbon dioxide and obtain mixed gas 2; 3. Primary gas-solid separation The mixed gas 2 after fluidized bed separation is subjected to a primary gas-solid separation to remove particles with a particle size greater than 250 μm; after the separation is completed, a mixed gas 3 is obtained; 4. Secondary gas-solid separation The mixed gas is subjected to a second-stage gas-solid separation to remove particles with a diameter greater than 10 μm, thereby obtaining carbonyl fluoride from which carbon dioxide and granular powder are removed.

2. A method for removing carbon dioxide from carbonyl fluoride according to claim 1, characterized in that: In step 2, the preparation method of sodium methoxide solid particle impurity remover comprises the following steps: S1, dissolving povidone in ethanol to form a povidone ethanol solution with a mass concentration of 0.5% to obtain an adhesive; S2, placing sodium methoxide and a binder in a granulator to granulate; S3. After granulation, the mixture is dried at 40° C. and passed through a 40-60 mesh sieve to obtain the sodium methoxide solid particle impurity remover.

3. A method for removing carbon dioxide from carbonyl fluoride according to claim 1, characterized in that: The reaction temperature in step 1 is 90-120°C.

4. The device used in the method for removing carbon dioxide from carbonyl fluoride according to any one of claims 1 to 3, characterized in that: It includes a preheating device, a gas-solid fluidized bed reactor, a first-stage cyclone separator, and a second-stage cyclone separator which are connected in sequence; Preheating device: used to implement the preheating process in step 1; Gas-solid fluidized bed reactor: It is filled with sodium methoxide solid particle impurity remover, the bottom is connected to the preheating device through a pipeline, and the top is connected to the top of the first-stage cyclone separator; First-stage cyclone separator: The bottom is connected to the gas-solid fluidized bed; the critical particle size of separation is 250μm; Secondary cyclone separator: The critical particle size for separation is 10 μm, and an ash hopper is provided at the bottom.

5. The device for removing carbon dioxide from carbonyl fluoride according to claim 4, characterized in that: The operating temperature of the gas-solid fluidized bed reactor is 90-120° C., the operating pressure is atmospheric pressure, the inlet gas velocity is 0.43-0.1 m / s, the critical fluidization velocity is 0.067 m / s, and the carry-out velocity is 0.78 m / s.

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