Method for purifying high-purity electronic grade ethylene
阅读说明：本技术 一种高纯电子级乙烯的提纯方法 (Method for purifying high-purity electronic grade ethylene ) 是由 马建修 靖宇 杜文东 于 2021-08-25 设计创作，主要内容包括：本发明提出一种高纯电子级乙烯的提纯方法,涉及乙烯提纯技术领域。上述高纯电子级乙烯的提纯方法包括以下步骤：以液氮为冷媒的两级低温精馏处理工业级乙烯制得一级乙烯粗品,两级低温精馏的温度分别为T1、T2,压力分别为P1、P2,液氮质量流量分别为N1、N2,回流分别为R1、R2；其中,-100℃≤T2<T1≤-83℃,0.1MPa≤P2<P1≤0.5MPa,40≤R1≤50,40≤R2≤50,N1≠N 2；将一级乙烯粗品经变压吸附制得二级乙烯粗品；采用经钝化处理的特殊沸石分子筛对二级乙烯粗品进行脱水。上述提纯方法通过以液氮为冷媒的两级低温精馏、变压吸附、脱水实现工业级乙烯的提纯,制得的乙烯纯度高。(The invention provides a method for purifying high-purity electronic grade ethylene, and relates to the technical field of ethylene purification. The purification method of the high-purity electronic grade ethylene comprises the following steps: processing industrial-grade ethylene by two-stage cryogenic rectification with liquid nitrogen as a refrigerant to obtain a primary ethylene crude product, wherein the two-stage cryogenic rectification has the temperatures of T1 and T2, the pressures of P1 and P2, the mass flow rates of the liquid nitrogen are N1 and N2, and the reflux is R1 and R2; wherein T2 is more than or equal to-100 ℃ and less than T1 and less than or equal to-83 ℃, P2 is more than or equal to 0.1MPa and less than or equal to P1 and less than or equal to 0.5MPa, R1 is more than or equal to 40 and less than or equal to 50, R2 is more than or equal to 40 and less than or equal to 50, and N1 is not equal to N2; carrying out pressure swing adsorption on the primary ethylene crude product to prepare a secondary ethylene crude product; and dehydrating the secondary ethylene crude product by using a special passivated zeolite molecular sieve. The purification method realizes the purification of industrial-grade ethylene by two-stage low-temperature rectification, pressure swing adsorption and dehydration with liquid nitrogen as a refrigerant, and the prepared ethylene has high purity.)
1. A method for purifying high-purity electronic grade ethylene is characterized by comprising the following steps:
and step S1: the method comprises the following steps of (1) processing industrial-grade ethylene by two-stage cryogenic rectification with liquid nitrogen as a refrigerant to remove heavy components and light components to prepare a primary ethylene crude product, wherein the two-stage cryogenic rectification has the temperature of T1 and the temperature of T2, the pressure of P1 and the pressure of P2, the mass flow of the liquid nitrogen is N1 and N2, and the reflux is R1 and R2; wherein T2 is more than or equal to-100 ℃ and less than T1 and less than or equal to-83 ℃, P2 is more than or equal to 0.1MPa and less than or equal to P1 and less than or equal to 0.5MPa, R1 is more than or equal to 40 and less than or equal to 50, R2 is more than or equal to 40 and less than or equal to 50, and N1 is not equal to N2;
and step S2: carrying out pressure swing adsorption on the primary ethylene crude product to prepare a secondary ethylene crude product;
and step S3: and dehydrating the secondary ethylene crude product by using a special passivated zeolite molecular sieve.
2. The method of claim 1, wherein in step S1, when N1> N2, the first rectifying tower of the two-stage cryogenic rectification removes heavy components, and the second rectifying tower removes light components.
3. The method of claim 1, wherein in step S1, when N1< N2, the first rectifying tower of the two-stage cryogenic rectification removes light components, and the second rectifying tower removes heavy components.
4. The method of claim 1, wherein in step S2, the pressure swing adsorption uses modified carbon molecular sieve impregnated with acetone as adsorbent.
5. The method of claim 4, wherein in the step of S2, the pressure swing adsorption is shifted by low pressure 0.08-0.12 MPa and high pressure 0.64-0.96MPa, and the shifting frequency is 24-36S.
6. The method of claim 5, wherein the pressure swing adsorption temperature is 300 ℃ in the step S2.
7. The method of claim 1, wherein in the step of S3, the special zeolite molecular sieve is a mixture of 5A molecular sieve and 4A molecular sieve.
8. The method as claimed in claim 7, wherein in the step S3, the pressure of the dehydration operation is 0.1-0.4MPa, the temperature is from room temperature to 80 ℃, and the space velocity is 200-300/h.
9. The method of claim 7, wherein the passivation treatment in step S3 comprises the following steps:
s301: with a volume fraction of 0.01% SO2The gas is passivation gas to perform passivation treatment on the special zeolite molecular sieve;
s302, step: and (3) after the special zeolite molecular sieve is activated by nitrogen blowing at high temperature, vacuumizing and replacing.
10. The method for purifying high purity electronic grade ethylene according to claim 9, wherein in the step S301, the mass ratio of the content of sulfur in the passivation gas to the mass ratio of the special zeolite molecular sieve is (0.01-0.05): 1.
Technical Field
The invention relates to the technical field of ethylene purification, and in particular relates to a method for purifying high-purity electronic grade ethylene.
Background
Ethylene (C)2H4) Is one of the important basic raw materials in the petrochemical industry, chemical products taking ethylene as a raw material have an important position in national economy, and the ethylene yield is used as a measure in the worldOne of the important marks of the national petrochemical industry and the economic development level. High-purity ethylene is widely applied to the industrial departments of metallurgy, electronics, chemical industry, petroleum and the like and the fields of basic research, atmospheric pollution monitoring, aviation, atomic energy and the like. The purity of ethylene used as standard gas, on-line instrument standard gas, correcting gas and special mixed gas is required to reach 4N5 (99.995%).
In the field of semiconductor wafer manufacturing, particularly 3D memory (3D-NAND) manufacturing, high purity electronic grade ethylene may be used in the deposition stages of an amorphous carbon layer, a hard mask carbon layer, and silicon carbide (silicon carbide) under a deep ultraviolet special photoresist, depending on the choice of process and equipment. The purity requirement is extremely strict and the purity of 5N5(99.9995%) is required. Especially, the contents of ethane, acetylene, methane, oxygen, carbon dioxide and water are required to avoid the influence of other hydrocarbon impurities on the thickness and uniformity of the deposited amorphous carbon layer, the density and the geometric appearance of the deposited layer framework under the same Chemical Vapor Deposition (CVD) operating conditions.
China is a big country for producing ethylene, the source of industrial-grade coarse materials is wide, and the method for obtaining high-purity electronic-grade ethylene by separating and purifying the industrial-grade ethylene raw material is a good means. However, in the conventional process, the following technical problems still need to be solved in the industrial process of purifying industrial-grade ethylene raw material to high-purity electronic-grade ethylene by rectification:
(1) the separation of ethylene and ethane is difficult, the tower is extremely high or the energy consumption is huge. The separation factor between ethylene and ethane was about 2.67 and the theoretical plate number from 99.5% purification to 5N5 was about 150 and 180.
(2) The same polar molecules are easy to be carried along by constant boiling in the trace range of ppm level, such as acetylene and carbon dioxide. And thus difficult to separate by means of rectification.
(3) Because the deep dehydration molecular sieve reacts with ethylene, trace water is difficult to remove to less than 1 ppm.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention aims to provide a method for purifying high-purity electronic-grade ethylene, which realizes the purification of industrial-grade ethylene by two-stage low-temperature rectification, pressure swing adsorption and dehydration by using liquid nitrogen as a refrigerant, and the purity of the prepared ethylene reaches 5N5 (99.9995%).
The technical problem to be solved by the invention is realized by adopting the following technical scheme.
The invention provides a method for purifying high-purity electronic grade ethylene, which comprises the following steps:
and step S1: the method comprises the following steps of (1) processing industrial-grade ethylene by two-stage cryogenic rectification with liquid nitrogen as a refrigerant to remove heavy components and light components to prepare a primary ethylene crude product, wherein the two-stage cryogenic rectification has the temperatures of T1 and T2, the pressures of P1 and P2, the mass flow rates of the liquid nitrogen are N1 and N2, and the reflux is R1 and R2; wherein T2 is more than or equal to-100 ℃ and less than T1 and less than or equal to-83 ℃, P2 is more than or equal to 0.1MPa and less than or equal to P1 and less than or equal to 0.5MPa, R1 is more than or equal to 40 and less than or equal to 50, R2 is more than or equal to 40 and less than or equal to 50, and N1 is not equal to N2;
and step S2: carrying out pressure swing adsorption on the primary ethylene crude product to prepare a secondary ethylene crude product;
and step S3: and dehydrating the secondary ethylene crude product by using a special passivated zeolite molecular sieve.
Preferably, in the S1 step, when N1> N2, the first rectifying tower of the two-stage cryogenic rectification removes heavy components, and the second rectifying tower removes light components.
Preferably, in the S1 step, when N1< N2, the first rectifying tower of the two-stage cryogenic rectification removes light components, and the second rectifying tower removes heavy components.
Preferably, in the step S2, the adsorbent used in the pressure swing adsorption is a modified carbon molecular sieve impregnated with acetone.
Preferably, in the step S2, the pressure swing adsorption is changed by adopting low pressure of 0.08-0.12 MPa and high pressure of 0.64-0.96MPa, and the changing frequency is 24-36S.
Preferably, the pressure swing adsorption temperature in step S2 is 300 ℃.
Preferably, in the step S3, the special zeolite molecular sieve is a mixture of 5A molecular sieve and 4A molecular sieve.
Preferably, in the step S3, the pressure of the dehydration operation is 0.1-0.4MPa, the temperature is between room temperature and 80 ℃, and the space velocity is 200-300/h.
Preferably, in the step S3, the passivation process includes the steps of:
s301: with a volume fraction of 0.01% SO2The gas is passivation gas for passivating the special zeolite molecular sieve;
s302, step: after the nitrogen is blown and activated at high temperature, the special zeolite molecular sieve is vacuumized and replaced.
Preferably, in the step S301, the mass ratio of the sulfur content in the passivation gas to the specific zeolite molecular sieve is (0.01-0.05): 1.
preferably, the operation temperature of the step S301 is 300 ℃ and the time is 30 min.
The method for purifying the high-purity electronic grade ethylene has the advantages that:
(1) the invention adopts two-stage low-temperature rectification with liquid nitrogen as a refrigerant to separate ethane, thereby reducing equipment investment and improving separation effect.
(2) The pressure swing adsorption system is adopted to separate the azeotropic substance, so that the effective separation of acetylene and carbon dioxide is realized.
(3) The special zeolite molecular sieve for passivation treatment is adopted for dehydration, and the technical effect that trace water is removed to be within 1ppm is realized.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Ethylene (Ethylene) of the formula C2H4Molecular weight 28.06, is a compound consisting of two carbon atoms and four hydrogen atoms. Its melting point is-169.4 ℃ and its boiling point is-103.9 ℃.
The embodiment of the invention provides a method for purifying high-purity electronic grade ethylene, which comprises the following steps:
and step S1: two-stage low-temperature rectification method using liquid nitrogen as refrigerant for removing heavy components and light components from industrial-grade ethyleneObtaining a first-stage ethylene crude product, wherein the temperature of two-stage cryogenic rectification is T1 and T2 respectively, the pressure is P1 and P2 respectively, the mass flow rate of liquid nitrogen is N1 and N2 respectively, and the reflux is R1 and R2 respectively; wherein T2 is more than or equal to-100 DEG C< T1≤-83℃, 0.1MPa≤P2<P1 is less than or equal to 0.5MPa, R1 is less than or equal to 40 and less than or equal to 50, R2 is less than or equal to 40 and less than or equal to 50, and N1 is not equal to N2; the industrial-grade ethylene can be separated and purified from other hydrocarbons, most of which is ethane, by a two-stage cryogenic rectification method taking liquid nitrogen as a refrigerant in the step S1. By controlling T2< T1, P2<P1 can make the material in the first rectifying tower smoothly press into the second rectifying tower. Adjusting the mass flow rates of liquid nitrogen in the first rectifying tower and the second rectifying tower of the two-stage low-temperature rectification to be N1 and N2 respectively, and adjusting the removal of heavy components (C)2H6And hydrocarbons having a carbon number greater than 3) or a light component (N)2、CO、O2、Ar、CH4 ). By this step, N in technical grade ethylene2、CO、O2、Ar、CH4、C2H6And hydrocarbons with carbon numbers greater than 3) are removed altogether. The liquid nitrogen is used as a refrigerant, so that the temperature of the rectification operation can be effectively reduced, the reflux ratio is reduced to 40-50, and the separation efficiency is greatly improved, so that the energy consumption and the number of tower plates of the rectification tower are reduced, and the equipment investment cost (about 60-70 meters higher than the high-temperature high-pressure rectification tower and now reduced to 20-30 meters) and the production cost (the reflux ratio is originally 70-80 and now reduced to 40-50) are greatly reduced. The reflux ratio is adjusted according to the actual production condition.
Further, in the preferred embodiment of the invention, when N1> N2, the first rectification column of the two-stage cryogenic rectification removes heavy components and the second rectification column removes light components.
Further, in the preferred embodiment of the invention, when N1< N2, the first rectification column of the two-stage cryogenic rectification removes light components and the second rectification column removes heavy components.
And step S2: carrying out pressure swing adsorption on the primary ethylene crude product to prepare a secondary ethylene crude product; separating the azeotropic substance in the first-stage ethylene crude product by pressure swing adsorption. Mainly acetylene and carbon dioxide.
Further, in the preferred embodiment of the present invention, the pressure swing adsorption employs acetone as the adsorbentImpregnating the modified carbon molecular sieve. The carbon molecular sieve is oxygen-free and aluminum-free, has no active center, and can not open ethylene double bonds, polymerize or adsorb with the carbon molecular sieve in the adsorption process. While carbon dioxide is readily polarized (polarizability a =2.76 × 10)-24 cm3) The negative charge of oxygen is high, and the positive charge of carbon is high; acetylene is very easily ionized in organics (ionization coefficient pKa = 25) to produce HC ≡ C-and H +. The two gas molecules present a Knudsen diffusion mechanism in the pore channel of the adsorbent, are easy to polarize and ionize, so the polarity is strong, and the carbon molecular sieve is similar to the impregnated acetone molecules and compatible with the impregnated acetone molecules, therefore, the carbon molecular sieve modified by acetone impregnation can effectively treat CO2Adsorbing with acetylene to remove CO2And the technical effect of acetylene.
Further, in the preferred embodiment of the present invention, the pressure swing adsorption is shifted by using a low pressure of 0.08-0.12 MPa and a high pressure of 0.64-0.96MPa, and the shifting frequency is 24-36 s.
Further, in the preferred embodiment of the present invention, the pressure swing adsorption temperature is 300 ℃.
And step S3: and dehydrating the secondary ethylene crude product by using a special passivated zeolite molecular sieve. The activity of the molecular sieve can be effectively reduced by passivating the molecular sieve.
Further, in the preferred embodiment of the present invention, the specific zeolite molecular sieve is a mixture of 5A molecular sieve and 4A molecular sieve.
Further, in the preferred embodiment of the present invention, the pressure of the dehydration operation is 0.1-0.4MPa, the temperature is from room temperature to 80 ℃, and the space velocity is 200-.
Further, in a preferred embodiment of the present invention, the passivation process comprises the steps of:
s301: with a volume fraction of 0.01% SO2Passivating the special zeolite molecular sieve for passivation gas;
s302, step: after the nitrogen is blown and activated at high temperature, the special zeolite molecular sieve is vacuumized and replaced.
Further, in the preferred embodiment of the present invention, the mass ratio of the sulfur content in the passivation gas to the specific zeolite molecular sieve is (0.01-0.05): 1.
the features and properties of the present invention are described in further detail below with reference to examples.
Example 1
The embodiment provides a method for purifying high-purity electronic grade ethylene, which comprises the following steps:
and step S1: a first rectifying tower and a second rectifying tower which take liquid nitrogen as a refrigerant form a two-stage low-temperature rectifying section, and industrial-grade ethylene is processed to remove heavy components and light components to obtain a primary ethylene crude product. Wherein the temperatures of the first rectifying tower and the second rectifying tower are-83 ℃ and-100 ℃ respectively. The pressures were 0.5MPa and 0.1MPa, respectively. The mass flow of liquid nitrogen is 0.01m3/s、0.02m3The reflux ratio was 43 in each case. At this time, the first rectifying tower of the two-stage cryogenic rectification removes light components, and the second rectifying tower removes heavy components. In this embodiment, the mass flow rate N1 of the first rectifying tower is smaller than the mass flow rate N2 of the second rectifying tower, the first rectifying tower of the two-stage low-temperature rectification removes light components, and the second rectifying tower removes heavy components. In other embodiments, the mass flow rate N1 of the first rectifying tower is greater than the mass flow rate N2 of the second rectifying tower, and the first rectifying tower for cryogenic rectification removes heavy components and the second rectifying tower removes light components. It is within the scope of the present embodiment as long as the effect of jointly removing the light components and the heavy components by the first rectifying column and the second rectifying column can be achieved.
And step S2: carrying out pressure swing adsorption on the primary ethylene crude product at 300 ℃ to prepare a secondary ethylene crude product; the adsorbent adopted by the pressure swing adsorption is a carbon molecular sieve modified by acetone impregnation. The pressure swing adsorption adopts the transformation of low pressure 0.10 MPa and high pressure 0.80MPa, and the transformation frequency is 30 s.
And step S3:
s301: adopting 0.01 percent SO by volume fraction at the high temperature of 300 DEG C2(the remainder being N)2) The gas is passivation gas for carrying out passivation treatment on the special zeolite molecular sieve for 30 min; the mass ratio of the sulfur content in the passivation gas to the special zeolite molecular sieve is 0.03: 1. the particular zeolitic molecular sieve in this example is a mixture of 5A molecular sieve and 4A molecular sieve. In other embodiments, other molecular sieves are possibleIt is within the scope of the present embodiment as long as the dehydration can be achieved without reacting with ethylene.
S302, step: after the nitrogen is blown and activated at high temperature, the special zeolite molecular sieve is vacuumized and replaced.
The special zeolite molecular sieve after passivation treatment in the steps dehydrates the secondary ethylene crude product under the conditions that the pressure is 0.3MPa, the temperature is 50 ℃ and the airspeed is 250/h.
Example 2
This example provides a method for purifying high purity electronic grade ethylene, comprising the steps of:
and step S1: a first rectifying tower and a second rectifying tower which take liquid nitrogen as a refrigerant form a two-stage low-temperature rectifying section, and industrial-grade ethylene is processed to remove heavy components and light components to obtain a primary ethylene crude product. Wherein the temperatures of the first rectifying tower and the second rectifying tower are-88 ℃ and-95 ℃ respectively. The pressures were 0.4MPa and 0.2 MPa, respectively. The mass flow of liquid nitrogen is 0.01m3/s、0.15m3The reflux ratios were 40 and 45, respectively. At this time, the first rectifying tower of the two-stage cryogenic rectification removes light components, and the second rectifying tower removes heavy components. In this embodiment, the mass flow rate N1 of the first rectifying tower is smaller than the mass flow rate N2 of the second rectifying tower, the first rectifying tower of the two-stage low-temperature rectification removes light components, and the second rectifying tower removes heavy components. In other embodiments, the mass flow rate N1 of the first rectifying tower is greater than the mass flow rate N2 of the second rectifying tower, and the first rectifying tower for cryogenic rectification removes heavy components and the second rectifying tower removes light components. It is within the scope of the present embodiment as long as the effect of jointly removing the light components and the heavy components by the first rectifying column and the second rectifying column can be achieved.
And step S2: carrying out pressure swing adsorption on the primary ethylene crude product at 300 ℃ to prepare a secondary ethylene crude product; the adsorbent adopted by the pressure swing adsorption is a carbon molecular sieve modified by acetone impregnation. The pressure swing adsorption adopts the transformation of low pressure 0.08 MPa and high pressure 0.96MPa, and the transformation frequency is 24 s.
And step S3:
s301: adopting 0.01 percent SO by volume fraction at the high temperature of 300 DEG C2(the remainder beingN2) The gas is passivation gas for carrying out passivation treatment on the special zeolite molecular sieve for 30 min; the mass ratio of the sulfur content in the passivation gas to the special zeolite molecular sieve is 0.01: 1. the particular zeolitic molecular sieve in this example is a mixture of 5A molecular sieve and 4A molecular sieve. In other embodiments, other molecular sieves are also possible, and are within the scope of the present embodiment as long as they can achieve the dehydration and do not react with ethylene.
S302, step: after the nitrogen is blown and activated at high temperature, the special zeolite molecular sieve is vacuumized and replaced.
The special zeolite molecular sieve after passivation treatment in the steps dehydrates the secondary ethylene crude product under the conditions that the pressure is 0.4MPa, the temperature is room temperature and the airspeed is 300/h.
Example 3
This example provides a method for purifying high purity electronic grade ethylene, comprising the steps of:
and step S1: a first rectifying tower and a second rectifying tower which take liquid nitrogen as a refrigerant form a two-stage low-temperature rectifying section, and industrial-grade ethylene is processed to remove heavy components and light components to obtain a primary ethylene crude product. Wherein the temperatures of the first rectifying tower and the second rectifying tower are-83 ℃ and-100 ℃ respectively. The pressures were 0.5MPa and 0.1MPa, respectively. The mass flow of liquid nitrogen is 0.01m3/s、0.15m3The reflux ratios were all 50. At this time, the first rectifying tower of the two-stage cryogenic rectification removes light components, and the second rectifying tower removes heavy components. In this embodiment, the mass flow rate N1 of the first rectifying tower is smaller than the mass flow rate N2 of the second rectifying tower, the first rectifying tower of the two-stage low-temperature rectification removes light components, and the second rectifying tower removes heavy components. In other embodiments, the mass flow rate N1 of the first rectifying tower is greater than the mass flow rate N2 of the second rectifying tower, and the first rectifying tower for cryogenic rectification removes heavy components and the second rectifying tower removes light components. It is within the scope of the present embodiment as long as the effect of jointly removing the light components and the heavy components by the first rectifying column and the second rectifying column can be achieved.
And step S2: carrying out pressure swing adsorption on the primary ethylene crude product at 300 ℃ to prepare a secondary ethylene crude product; the adsorbent adopted by the pressure swing adsorption is a carbon molecular sieve modified by acetone impregnation. The pressure swing adsorption adopts the transformation of low pressure 0.12 MPa and high pressure 0.64MPa, and the transformation frequency is 36 s.
And step S3:
s301: adopting 0.01 percent SO by volume fraction at the high temperature of 300 DEG C2(the remainder being N)2) The gas is passivation gas for carrying out passivation treatment on the special zeolite molecular sieve for 30 min; the mass ratio of the sulfur content in the passivation gas to the special zeolite molecular sieve is 0.05: 1. the particular zeolitic molecular sieve in this example is a mixture of 5A molecular sieve and 4A molecular sieve. In other embodiments, other molecular sieves are also possible, and are within the scope of the present embodiment as long as they can achieve the dehydration and do not react with ethylene.
S302, step: after the nitrogen is blown and activated at high temperature, the special zeolite molecular sieve is vacuumized and replaced.
The special zeolite molecular sieve after passivation treatment in the steps dehydrates the secondary ethylene crude product under the conditions that the pressure is 0.1MPa, the temperature is room temperature and the airspeed is 200/h.
Test example 1
The composition of the industrial grade ethylene feed is as follows:
TABLE 1 feed composition of technical grade ethylene and target content of high purity electronic grade ethylene
Technical grade ethylene feedstock composition
Boiling point (. degree.C.)
Content of raw materials
Target content of high purity electronic grade ethylene
Unit of
C2H4
-104
99.5
99.9995
%
N2
-196
80
<1
10-6(ppmv)
CO
-191
10
<1
10-6(ppmv)
O2+Ar
-183
20
<1
10-6(ppmv)
CH4
-161
500
<1
10-6(ppmv)
C2H6
-89
1000
<1
10-6(ppmv)
C2H2
-84
5
<1
10-6(ppmv)
CO2
-78
50
<1
10-6(ppmv)
Other hydrocarbons (e.g. propylene having a carbon number greater than 3)
<4000
<4
10-6(ppmv)
H2O
5
<1
10-6(ppmv)
Total impurities
<5000 ppm
<5
10-6(ppmv)
This test example is intended to explain the method of evaluating the purity of ethylene. In the experimental example, the device Agilent 7820 is used for measuring the hydrocarbon impurities in the ethylene for GB/T3391-2002 industry, the ethylene and the trace water in the propylene for GB/T3727-2003 industry, the ethylene and the trace carbon monoxide, the carbon dioxide and the acetylene for GB/T3394-2009 industry and the ethylene and the trace hydrogen in the propylene for GB/T3393-2009 are used for measuring the gas chromatography of the H in the high-purity electronic grade ethylene purified in the embodiments 1 to 32O、N2、CO、O2、Ar、CH4、C2H6、C2H2、CO2And a content of hydrocarbons having a carbon number greater than 3.
Pre-separation column: a 316L stainless steel column having a length of about 5m and an inner diameter of 2mm, and loaded with Porapak Q (high molecular polymer) having a particle size of 0.18mm to 0.25 mm.
A chromatographic column I: the analysis device comprises a 316L stainless steel column with the length of about 2m and the inner diameter of 2mm, and a 5A molecular sieve with the particle size of 0.18 mm-0.25 mm is filled in the column and is used for analyzing water, oxygen, argon and nitrogen.
And (2) chromatographic column II: the analysis device comprises a 316L stainless steel column which is about 2m long and 2mm in inner diameter, wherein HayeSep DB (high molecular polymer) with the grain diameter of 0.18 mm-0.25 mm is filled in the column and is used for analyzing the content of carbon monoxide, methane, carbon dioxide, ethane, acetylene and hydrocarbons with the carbon number more than 3.
Standard samples: the volume fraction of the component content is 2 x 10-6The balance gas is helium.
Ethylene purity calculation formula:
A=100-（A1+ A2+ A3+ A4+ A5+ A6+ A7）*10-4
in the formula:
a: content of Nitrogen (volume fraction), 10-2；
A1: carbon monoxide content (volume fraction), 10-6；
A2: oxygen + argon content (volume fraction), 10-6；
A3: content of methane (volume fraction), 10-6；
A4: ethane content (volume fraction), 10-6；
A5: carbon dioxide content (volume fraction), 10-6；
A6: content of hydrocarbons having carbon number of more than 3 (volume fraction), 10-6；
A7: water content (volume fraction), 10-6；
The results of test example 1 are shown in Table 2 below
TABLE 2 purity of high purity electronic grade ethylene purified in examples 1-3
Purity of ethylene (%)
Example 1
99.9998%
Example 2
99.9996%
Example 3
99.9995%
In conclusion, the purification method of high-purity electronic grade ethylene provided by the invention realizes the purification of industrial grade ethylene by two-stage low-temperature rectification, pressure swing adsorption and dehydration with liquid nitrogen as a refrigerant, and the purity of the prepared ethylene reaches 5N5 (99.9995%). As can be seen from Table 2, the purity of the ethylene obtained in examples 1-3 all reached 5N5, and the purity of the ethylene obtained in example 1 was the highest, and the above purification process solved the technical problem of difficulty in purifying ethylene in actual production. The invention adopts two-stage low-temperature rectification with liquid nitrogen as a refrigerant to separate ethane, thereby reducing equipment investment and improving separation effect. The pressure swing adsorption system is adopted to separate the azeotropic substance, so that the effective separation of acetylene and carbon dioxide is realized. The special zeolite molecular sieve for passivation treatment is adopted for dehydration, and the technical effect that trace water is removed to be within 1ppm is realized.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
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