A method for purifying high-purity propylene

Abstract

The present application discloses a method for purifying high-purity propylene, comprising: passing an industrial-grade propylene raw material into a condensation device for at least one condensation treatment to remove heavy components therefrom; analyzing and testing the product that has undergone at least one condensation treatment, and if the analysis fails, returning it for further condensation treatment until the analysis passes; passing the qualified product into an adsorption device for adsorption treatment to remove carbon dioxide and water therefrom; passing the adsorption-treated product into a distillation device for distillation treatment to remove light components therefrom; passing the distillation-treated product into a buffer tank for filling, thereby obtaining the high-purity propylene. The high-purity propylene purification method of the present application utilizes a combination of low-temperature liquefaction, adsorption, and distillation to directly purify industrial propylene with a purity of ≥2.5N into electronic-grade high-purity propylene with a purity greater than 4N.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation, and in particular to a method for purifying high-purity propylene. Background Art

[0002] Electronic-grade propylene is a very important new industrial basic material, widely used in semiconductor integrated circuit (IC) processes, liquid crystal displays (LCD), semiconductor light-emitting devices (LED), and solar cells (PV). It can also be used as a film-forming gas, mainly for the growth of amorphous silicon carbon.

[0003] In recent years, with the gradual decline of global oil and other energy resources, environmental pollution, and the impact of the greenhouse effect on the climate, countries around the world have vigorously developed clean energy and energy-saving technologies, focusing on low-carbon economies. Against this backdrop, my country's solar cells, semiconductor light-emitting devices, and related industries have experienced rapid development, creating a vast market for electronic-grade propylene.

[0004] Generally, when industrial-grade propylene is used as a raw material for petrochemical products such as polypropylene and ethylene oxide, the purity of propylene is ≥2.5N. The impurities contained in industrial-grade propylene will cause certain defects in semiconductor technology and cause serious harm. According to process requirements, propylene ≥2.5N needs to be purified to ≥4N to meet the use requirements of electronic-grade special gases.

[0005] Currently, electronic-grade propylene can be purified by adsorption, distillation, or a combination of these methods. The adsorption method has certain requirements for the composition of the raw materials, which must not contain high-boiling-point components or easily polymerized substances. It is suitable for small-batch production of high-purity propylene. The distillation method has low relative volatility of propylene and propane, especially when the propylene concentration is high, where the relative volatility is almost close to 1 and the reflux ratio is much greater than the number of plates, making separation extremely difficult, complex, and costly. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides a method for purifying high-purity propylene, which directly purifies industrial propylene with a purity of ≥2.5N into electronic grade high-purity propylene with a purity greater than 4N by combining low-temperature liquefaction, adsorption and distillation.

[0007] The technical solutions of the present invention are as follows:

[0008] A method for purifying high-purity propylene, comprising:

[0009] Passing the industrial-grade propylene raw material into a condensation device for at least one condensation treatment to remove heavy components therein;

[0010] The product that has been subjected to at least one condensation treatment is subjected to analytical testing. If the analysis fails, it is returned for further condensation treatment until the analysis passes.

[0011] The qualified products are passed into the adsorption device for adsorption treatment to remove carbon dioxide and water;

[0012] The adsorption product is passed into a distillation unit for distillation to remove light components.

[0013] The product after the rectification treatment is passed into the buffer tank for filling, thereby obtaining the high-purity propylene.

[0014] Optionally, the condensing device includes a first condensing device and a second condensing device connected in sequence, the first condensing device is used to remove heavy components, and the second condensing device is used to deeply remove heavy components.

[0015] Optionally, the indicators of the analysis and test include:

[0016] Propane ≤ 80ppm, water ≤ 2ppm, the sum of butane, methylacetylene, propadiene, butylene and butadiene ≤ 10ppm;

[0017] The analysis is considered qualified only when all the above indicators are met.

[0018] Optionally, the temperature of the first condensing device and the second condensing device is -46 to -40°C.

[0019] Optionally, the refrigerant in the condensing device is any one of ethanol, ethylene glycol, liquid nitrogen, liquid ammonia, R32, R12, R134a or R407c.

[0020] Optionally, it also includes a controller and a temperature sensor arranged outside the condensing device, the temperature sensor is used to obtain the current temperature data of the condensing device and feed it back to the controller, the controller is connected to the condensing device, and is used to adjust the flow rate and / or type of the refrigerant in the condensing device according to the temperature data fed back by the temperature sensor.

[0021] Optionally, the adsorbent in the adsorption device is a combination of one or more of molecular sieve, activated carbon, alumina or silica gel.

[0022] Optionally, a refrigerant cold preservation device is installed outside the buffer tank to liquefy the propylene gas therein into propylene liquid; the refrigerant in the refrigerant cold preservation device is any one of ethanol, ethylene glycol, liquid nitrogen, liquid ammonia, R32, R12, R134a or R407c.

[0023] Optionally, the top temperature of the distillation device is -25 to -14°C, the bottom temperature is -25 to -14°C, and the tower pressure is 0.15 to 0.25 MPa.

[0024] Optionally, the purity of the obtained high-purity propylene is >4N.

[0025] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0026] (1) The high-purity propylene purification method of the present application directly purifies industrial propylene with a purity of ≥2.5N into electronic grade high-purity propylene with a purity greater than 4N by combining low-temperature liquefaction, adsorption and distillation.

[0027] (2) The method for purifying high-purity propylene of the present application solves the difficulty of separating propane from propylene, and at the same time removes the heavy components in propylene, reducing the heavy component removal process in the distillation process, that is, it can be produced in large quantities to meet the needs of customers in the semiconductor industry. It is also simple to operate, reduces the number of distillation tower plates, reduces costs, and the impurity index meets the electronic grade requirements. The goal of obtaining high-purity products from industrial-grade propylene through this process is achieved, and the effect of industrial production is achieved.

[0028] (3) The high-purity propylene purification process of the present application has the advantages of high safety, low equipment investment, low energy consumption, good economy, simple process operation, and high product purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a process flow chart of the method for purifying high-purity propylene according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] The present invention will be further described with reference to the accompanying drawings and embodiments:

[0031] Due to the drawbacks of the adsorption and distillation methods mentioned in the background of this application, which make it impossible to effectively separate propane from propylene, the inventors of this application have utilized the different physical properties of propane and propylene, namely, the boiling points, to employ a cryogenic condensation method. Through a series of precise temperature controls, propane is condensed into a liquid, thereby separating propylene from propane.

[0032] The boiling points of various components that may be involved in the industrial-grade propylene feedstock used in the examples of this application are shown in Table 1.

[0033] Table 1

[0034]

[0035]

[0036] Figure 1 This is a process flow chart of the method for purifying high-purity propylene according to an embodiment of the present application. Figure 1 , the present application provides a method for purifying high-purity propylene, comprising:

[0037] S1: Industrial-grade propylene feedstock is sequentially passed through a first condensing device and a second condensing device for two condensation treatments, wherein the first condensing device is used to remove heavy components, and the second condensing device is used to deeply remove heavy components; the temperature of the first condensing device and the second condensing device is -46 to -40°C; the refrigerant in the condensing device is any one of ethanol, ethylene glycol, liquid nitrogen, liquid ammonia, R32, R12, R134a or R407c;

[0038] S2: Analyze and test the product that has undergone at least one condensation treatment. If the product fails the analysis, return it to continue the condensation treatment until it passes the analysis.

[0039] S3: Passing the qualified products into an adsorption device for adsorption treatment to remove carbon dioxide and water therein, wherein the adsorbent in the adsorption device is a combination of one or more of molecular sieve, activated carbon, alumina or silica gel;

[0040] S4: passing the adsorption product into a distillation unit for distillation to remove light components, wherein the top temperature of the distillation unit is -25 to -14°C, the bottom temperature is -25 to -14°C, and the tower pressure is 0.15 to 0.25 MPa;

[0041] S5: The product after distillation is passed into a buffer tank and filled with a metering pump to obtain the high-purity propylene. A refrigerant cold preservation device is installed on the outside of the buffer tank to liquefy the propylene gas therein into propylene liquid. The refrigerant in the refrigerant cold preservation device is any one of ethanol, ethylene glycol, liquid nitrogen, liquid ammonia, R32, R12, R134a or R407c.

[0042] Furthermore, the embodiment of the present application also includes a controller for controlling the refrigerant medium and a temperature sensor arranged outside the condensing device, the temperature sensor is used to obtain the current temperature data of the condensing device and feed it back to the controller, the controller is connected to the condensing device, and is used to adjust the flow rate and / or type of the refrigerant in the condensing device according to the temperature data fed back by the temperature sensor.

[0043] In step S1, the industrial-grade propylene feedstock is passed through a two-stage condensing device to ensure that the propane and other heavy components in the propylene are completely condensed into liquids, thereby separating the propylene, propane, and the heavy components in the propylene. The cooling capacity provided by the refrigerant medium in the condensing device is controlled by controlling the temperature of the condensing device at -46 to -40°C. Regarding the selection of the refrigerant medium, in the embodiment of the present application, one can select one, or different refrigerant combinations can be selected according to the separation goals of propylene, propane, etc., that is, the type of refrigerant used to achieve the gas-liquid separation of propylene, propane, and other heavy components in propylene is selected.

[0044] In step S2, after the propane and other heavy components in the propylene are liquefied, the remaining gas after liquefaction is analyzed, and the propane and other heavy components in the propylene are analyzed and tested. If the analysis is qualified and meets the standards, it enters the adsorption column. If it does not meet the standards, it continues to return to the first and second condensing devices for condensation and liquefaction until it passes the test and then enters the adsorption column.

[0045] The analytical test indicators include: propane ≤ 80 ppm, water ≤ 2 ppm, and the sum of butane, methylacetylene, propadiene, butylene and butadiene ≤ 10 ppm;

[0046] The analysis is considered qualified only when all the above indicators are met.

[0047] After the above purification process of the present application, the purity of the obtained high-purity propylene is >4N.

[0048] Specific examples will be provided below and the purity of the obtained high-purity propylene will be analyzed.

[0049] [Example 1]

[0050] Passing industrial-grade propylene raw material into a first condensing device and a second condensing device, wherein the temperature of the first condensing device is -40°C and the refrigerant of the first condensing device is ethanol, and the temperature of the second condensing device is -46°C and the refrigerant of the second condensing device is ethylene glycol;

[0051] Only the products that had undergone two condensation treatments were analyzed and tested. The test results are shown in Table 2.

[0052] Table 2

[0053]

[0054]

[0055] The above test results show that the product after two condensation treatments has met the corresponding indicators. The qualified product is passed into the adsorption column, and the adsorbent is molecular sieve;

[0056] The adsorbed product was passed into a distillation unit with a top temperature of -15°C, a bottom temperature of -14°C, and a tower pressure of 0.25 MPa.

[0057] The distilled product was passed into a buffer tank equipped with a refrigerant cold-keeping device to liquefy the propylene. Samples were taken for purity analysis. The analysis results are shown in Table 3.

[0058] Table 3

[0059]

[0060] [Example 2]

[0061] Passing the industrial-grade propylene raw material into a first condensing device and a second condensing device, wherein the temperature of the first condensing device is -46°C and the refrigerant of the first condensing device is liquid nitrogen, and the temperature of the second condensing device is -40°C and the refrigerant of the second condensing device is liquid nitrogen;

[0062] Only the products that had undergone two condensation treatments were analyzed and tested. The test results are shown in Table 4.

[0063] Table 4

[0064]

[0065] The above test results show that the product after two condensation treatments has met the corresponding indicators. The qualified product is passed into the adsorption column, and the adsorbent is molecular sieve;

[0066] The adsorbed product was passed into a distillation unit with a top temperature of -25°C, a bottom temperature of -24°C, and a tower pressure of 0.15 MPa.

[0067] The distilled product was passed into a buffer tank equipped with a refrigerant cold-keeping device to liquefy the propylene. Samples were taken for purity analysis. The analysis results are shown in Table 5.

[0068] Table 5

[0069]

[0070]

[0071] [Example 3]

[0072] Passing industrial-grade propylene raw material into a first condensing device and a second condensing device, wherein the temperature of the first condensing device is -45°C and the refrigerant of the first condensing device is R32; the temperature of the second condensing device is -45°C and the refrigerant of the second condensing device is R32;

[0073] The products that had undergone two condensation treatments were only analyzed and tested. The test results are shown in Table 6.

[0074] Table 6

[0075]

[0076] The above test results show that the product after two condensation treatments has met the corresponding indicators. The qualified product is passed into the adsorption column, and the adsorbent is molecular sieve;

[0077] The adsorbed product was passed into a distillation unit with a top temperature of -25°C, a bottom temperature of -24°C, and a tower pressure of 0.15 MPa.

[0078] The distilled product was passed into a buffer tank equipped with a refrigerant cold-keeping device to liquefy the propylene. Samples were taken for purity analysis. The analysis results are shown in Table 7.

[0079] Table 7

[0080]

[0081] [Comparative Example 1]

[0082] Passing the industrial-grade propylene raw material into a first condensing device, wherein the temperature of the first condensing device is -46°C and the refrigerant of the first condensing device is ethanol;

[0083] Only the products that have undergone one condensation treatment were analyzed and tested. The test results are shown in Table 8.

[0084] Table 8

[0085]

[0086] From the above test results, it can be seen that after only one condensation treatment, the propane composition in the product still does not meet the standards.

[0087] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for purifying high-purity propylene, characterized in that: include: Passing the industrial-grade propylene raw material into a condensation device for at least one condensation treatment to remove heavy components therein; The product that has been subjected to at least one condensation treatment is subjected to analytical testing. If the analysis fails, it is returned for further condensation treatment until the analysis passes. The qualified products are passed into the adsorption device for adsorption treatment to remove carbon dioxide and water; The adsorption product is passed into a distillation unit for distillation to remove light components. Passing the distilled product into a buffer tank for filling, thereby obtaining the high-purity propylene; The condensing device comprises a first condensing device and a second condensing device connected in sequence, the first condensing device is used to remove the heavy components therein, and the second condensing device is used to deeply remove the heavy components therein; The temperature of the first condensing device and the second condensing device is -46 to -40°C.

2. The method for purifying high-purity propylene according to claim 1, wherein The indicators of the analytical test include: Propane ≤ 80ppm, water ≤ 2ppm, the sum of butane, methylacetylene, propadiene, butylene and butadiene ≤ 10ppm; The analysis is considered qualified only when all the above indicators are met.

3. The method for purifying high-purity propylene according to claim 1, wherein: The refrigerant in the condensing device is any one of ethanol, ethylene glycol, liquid nitrogen, liquid ammonia, R32, R12, R134a or R407c.

4. The method for purifying high-purity propylene according to claim 1, wherein: It also includes a controller and a temperature sensor arranged outside the condensing device, the temperature sensor is used to obtain the current temperature data of the condensing device and feed it back to the controller, the controller is connected to the condensing device, and is used to adjust the flow rate and / or type of the refrigerant in the condensing device according to the temperature data fed back by the temperature sensor.

5. The method for purifying high-purity propylene according to claim 1, wherein: The adsorbent in the adsorption device is a combination of one or more of molecular sieve, activated carbon, alumina or silica gel.

6. The method for purifying high-purity propylene according to claim 1, wherein: The buffer tank is externally provided with a refrigerant cold preservation device for liquefying the propylene gas therein into propylene liquid; the refrigerant in the refrigerant cold preservation device is any one of ethanol, ethylene glycol, liquid nitrogen, liquid ammonia, R32, R12, R134a or R407c.

7. The method for purifying high-purity propylene according to claim 6, wherein: The top temperature of the distillation device is -25 to -14°C, the bottom temperature is -25 to -14°C, and the tower pressure is 0.15 to 0.25 MPa.

8. The method for purifying high-purity propylene according to any one of claims 1 to 7, characterized in that: The purity of the obtained high-purity propylene is >4N.

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