CN113105303A - Refining method of hexafluorobutadiene - Google Patents
Refining method of hexafluorobutadiene Download PDFInfo
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- C07—ORGANIC CHEMISTRY
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Abstract
The invention relates to a refining method of hexafluorobutadiene, which comprises the steps of raw material pretreatment and purification of pretreated materials; the raw material pretreatment comprises an adsorption process of a hexafluorobutadiene raw material; the purification of the pretreated material is as follows: introducing the pretreated material into a secondary light component removal tower after primary light component removal and primary heavy component removal, and extracting a refined hexafluorobutadiene product from the lateral line of the secondary light component removal tower; in the purification process of the pretreated material, the first-stage light component removal is carried out in a first-stage light component removal tower, the first-stage heavy component removal is carried out in a heavy component removal tower, a cluster rectifying column is arranged in the heavy component removal tower, and the tower kettle extract of the second-stage light component removal tower is circularly introduced into the heavy component removal tower to remove heavy components. Compared with the prior art, the method can efficiently remove impurities in the raw material of the hexafluorobutadiene by combining multiple process methods such as cluster rectification (common rectification can be added in the raw material pretreatment process), side line extraction, adsorption and the like, so that the purity of the hexafluorobutadiene product can reach more than 99.995 percent, even 99.999 percent.
Description
Technical Field
The invention belongs to the technical field of purification of hexafluorobutadiene, and relates to a refining method of hexafluorobutadiene.
Background
Hexafluoro-1, 3-butadiene (C)4F6Hexafluorobutadiene for short) is a perfluorinated compound with a boiling point at atmospheric pressure of about 6 ℃, which was first used in the synthesis of fluorine-containing high molecular compounds. At present, the electron etching gas is mainly used in etching SiO and high-end process with a thickness of less than 7 nm. Since hexafluorobutadiene has the largest C/F ratio among all the electron etching gases and contains no H, it has a very high selectivity to Si or SiN on the substrate during SiO etching, and thus almost vertical etching can be achieved. At the same time, the atmospheric lifetime of hexafluorobutadiene is less than 2 days, GWP100The value of 290 is a new etching gas that has been found to meet the development requirements of etching techniques and minimize the environmental impact.
The hexafluorobutadiene containing an excessive amount of impurities may cause problems such as generation of wider lines during formation of fine patterns, increase of defects in integrated circuit products having high density, and the like in a semiconductor process, and selectivity of etching SiO is greatly reduced, so that development of a separation technique of the hexafluorobutadiene is very important for development of electronic information industry in China.
Chinese patent CN104529696A discloses a method for synthesizing and purifying hexafluorobutadiene, which comprises the steps of adding zinc powder, zinc chloride and an organic solvent into a reaction kettle, reacting with 1,2,3, 4-tetrachlorohexafluorobutane at 60-100 ℃ to generate hexafluorobutadiene, collecting a crude product through reflux condensation, and then obtaining a hexafluorobutadiene product with the purity of more than 95% by using batch rectification equipment.
Chinese patent CN106349008A discloses a method for purifying hexafluorobutadiene, which comprises the steps of firstly carrying out extraction separation on a solvent and adsorption dehydration by a molecular sieve, then using a high-efficiency adsorbent for adsorption, and finally carrying out reduced pressure rectification to obtain a hexafluorobutadiene product with the purity of more than 99.99%.
Chinese patent CN109180424A discloses a method and a device for purifying hexafluorobutadiene, which comprises the steps of firstly performing initial purification of hexafluorobutadiene by continuous rectification in two towers, then adsorbing impurities of a carbon halogen compound by an adsorption tower, then further purifying by a third rectification tower, and finally purifying by a filter, wherein the purity of the obtained hexafluorobutadiene is more than 99.99%.
Chinese patent CN107032949A discloses a method for purifying hexafluorobutadiene, which comprises adsorption and rectification steps, wherein in the adsorption step, at least one of ion exchange method, ball milling method or impregnation method is used to modify the adsorbent, so as to improve the purity of hexafluorobutadiene to more than 99.99%, even more than 99.999%.
Chinese patent CN108623432A discloses a process for preparing high-purity hexafluoro-1, 3-butadiene by an adsorption-cryogenic rectification method, which comprises the steps of sequentially removing organic and inorganic impurities by utilizing two-stage series adsorption, introducing the material subjected to adsorption treatment into a rectifying tower for cryogenic rectification, removing most of permanent gas and low-boiling organic impurities, and obtaining high-purity hexafluoro-butadiene with the purity of more than 99.99%.
However, in the above patent technology, CN104529696A adopts a batch rectification method to purify hexafluorobutadiene, but the product purity is only 95%, and deep purification is still needed to be used in the electronic industry; the CN106349008A comprises an extraction and rectification method in the purification, and an extracting agent is additionally introduced into the system, which is equivalent to artificially increasing impurities in the hexafluorobutadiene, and increasing the energy consumption and difficulty of the subsequent separation; in CN109180424A, a common rectification process is adopted to remove heavy components, so that the diameter of a rectifying tower is large, the packing efficiency is greatly reduced in practical use, the packing efficiency needs to be compensated by a large reflux ratio or a mode of increasing the height of the tower, the process is relatively backward, and the investment and operation cost is high; CN107032949A and CN108623432A both use the modified adsorbent of special technology, and the preparation process is complicated, and the industrialization cost is high.
Disclosure of Invention
The invention aims to provide a method for refining hexafluorobutadiene. The invention firstly carries out pretreatment on the raw material of the hexafluobutadiene to remove most of impurities, and the impurities of the pretreated material are further removed by purification to obtain the hexafluobutadiene product, wherein the purity of the hexafluobutadiene product can reach more than 99.995 percent, even 99.999 percent.
The purpose of the invention can be realized by the following technical scheme:
a method for refining hexafluorobutadiene, which comprises the steps of raw material pretreatment and purification of pretreated materials;
the raw material pretreatment comprises an adsorption process of a hexafluorobutadiene raw material to obtain a pretreated material;
the purification of the pretreated material comprises the following steps: introducing the pretreated material into a secondary light component removal tower after primary light component removal and primary heavy component removal, and extracting a refined hexafluorobutadiene product from the lateral line of the secondary light component removal tower;
in the purification process of the pretreated material, the first-stage lightness-removing is carried out in a first-stage lightness-removing tower, the first-stage weight-removing is carried out in a weight-removing tower, a cluster rectifying column is arranged in the weight-removing tower, and the tower kettle extract of the second-stage lightness-removing tower is circularly introduced into the weight-removing tower to remove heavy components.
Further, the raw material of the hexafluorobutadiene contains hexafluorobutadiene, a light component and a heavy component, the volume fraction of the hexafluorobutadiene is more than or equal to 60%, the light component is an organic matter which is contained in the raw material of the hexafluorobutadiene and has a lower atmospheric boiling point than that of the hexafluorobutadiene, and the heavy component is an organic matter which is contained in the raw material of the hexafluorobutadiene and has a higher atmospheric boiling point than that of the hexafluorobutadiene.
Further, when the volume fraction of the hexafluorobutadiene in the hexafluorobutadiene raw material is 60-95%, the raw material pretreatment is as follows: and introducing a hexafluorobutadiene raw material into a pre-de-heavy tower to remove heavy component impurities, and introducing a tower top extract of the pre-de-heavy tower into an adsorption device for adsorption to obtain a pretreated material.
Or when the volume fraction of the hexafluorobutadiene in the hexafluorobutadiene raw material is more than or equal to 95%, the raw material pretreatment is as follows: and introducing the hexafluorobutadiene raw material into an adsorption device for adsorption to obtain the pretreated material.
Further, the operating pressure of the adsorption device is 10-110kPaA, the operating temperature is 0-25 ℃, and the operating space velocity is 500--1。
Further, the adsorption device is filled with an adsorbent, and the adsorbent comprises one or more of a molecular sieve adsorbent, an activated alumina adsorbent, an activated carbon adsorbent or a salt adsorbent.
Further, in the purification process of the pretreated material, the pretreated material is firstly subjected to primary light component removal to remove light component impurities, then subjected to primary heavy component removal to remove heavy component impurities, and then introduced into a secondary light component removal tower.
Or in the purification process of the pretreated material, the pretreated material is firstly subjected to primary heavy component impurity removal, then subjected to primary light component impurity removal, and then introduced into a secondary light component removal tower.
Furthermore, in the heavy component removal tower, a liquid phase distributor and a gas phase distributor are respectively arranged at the upper part and the lower part of the cluster rectification column, and a gas-liquid phase distributor is arranged at a feed inlet of the heavy component removal tower.
Further, the overhead pressure of the first-stage lightness-removing tower is 50-250kPaA, and the reflux ratio is 4-50; the overhead pressure of the secondary light component removal tower is 50-250kPaA, the reflux ratio is 50-500, the overhead pressure of the heavy component removal tower is 50-250kPaA, and the reflux ratio is 0.5-5.
Wherein heavy component impurities are extracted from the tower bottom of the pre-heavy component removing tower and the tower bottom of the heavy component removing tower, and light component impurities are extracted from the tower top of the first-stage light component removing tower and the second-stage light component removing tower.
Compared with the prior art, the invention has the following characteristics:
1) the invention can efficiently remove impurities in the hexafluorobutadiene raw material by combining various process methods such as cluster rectification (common rectification can be added in the raw material pretreatment process), side line extraction, adsorption and the like, so that the purity of the hexafluorobutadiene product can reach more than 99.995 percent, even 99.999 percent;
2) the invention solves the problem of reduced filling efficiency in the rectification process, can directly use the commercial adsorbent without special modification, and has the advantages of high separation efficiency, simple process method, high product purity and low operation cost;
3) the de-heavy tower adopts a cluster rectification technology, so that the rectification efficiency is greatly improved;
4) and the material extracted from the tower kettle of the second-stage light component removal tower is introduced into the heavy component removal tower for circulation, so that the overall recovery rate of the hexafluobutadiene is improved.
Drawings
FIG. 1 is a schematic flow diagram of the pretreatment of the raw material in example 1;
FIG. 2 is a schematic diagram of the purification process of the pretreated material in example 1;
FIG. 3 is a schematic diagram of the purification process of the pretreated material in example 2;
the notation in the figure is:
1-pre-heavy component removal tower, 2-adsorption device, 3-first-stage light component removal tower, 4-heavy component removal tower and 5-second-stage light component removal tower.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
According to different preparation processes, the raw material of the hexafluorobutadiene contains halogenated hydrocarbon, ethanol, water, hydrogen fluoride, carbon dioxide, permanent gas and other impurities, wherein the halogenated hydrocarbon is C1-C5 halogenated olefin, halogenated alkane and halogenated alkyne, and the types are various and the separation difficulty is large. Among the above impurities, organic substances having a lower atmospheric boiling point than that of hexafluorobutadiene are light components, and higher organic substances are heavy components.
It has been found that the viscosity of the hexafluorobutadiene feedstock system is very low and that the efficiency of the filler in handling such materials is reduced. Through experimental measurement and calculation, the packing efficiency of the system is about 40% -80% of that of normal organic matters, and the phenomenon is more and more obvious along with the increase of the tower diameter. In the purification technology disclosed at present, the distillation process basically comprises the step of removing heavy components, which means that a distillation tower is needed to extract most of materials from the top of the tower, and a distillation tower with a large diameter is inevitably needed. If the packing efficiency is low, the reflux ratio needs to be increased or the packing height needs to be increased, either of which results in an increase in cost.
In order to solve the problems, the invention provides a method for refining hexafluorobutadiene, which comprises the steps of raw material pretreatment and purification of pretreated materials. In the raw material pretreatment, an appropriate adsorbent is filled through an adsorption device 2 to remove most of impurities, a bundle rectifying column is adopted in a de-weighting tower 4 in the purification process, the efficiency is improved, and finally a hexafluorobutadiene product with the purity of more than 99.995% is obtained.
1. Pretreatment of raw materials
As shown in fig. 1, when the volume fraction of the hexafluorobutadiene in the hexafluorobutadiene raw material is 60% to 95%, the raw material pretreatment is as follows: and (3) introducing a hexafluorobutadiene raw material into the pre-de-weighting tower 1 to remove heavy component impurities, and introducing the tower top extract of the pre-de-weighting tower 1 into an adsorption device 2 to be adsorbed to obtain a pretreated material. In the process for producing hexafluorobutadiene, basically, the step of mixing a solvent and reactants is included. After the reaction is completed, if the solvent and the reactant are excessively present in the hexafluorobutadiene, the removal in the pre-de-heavy column 1 is required before the purification. The separation difficulty of the partial solvent and the reactant is low, so that the pre-de-heavy tower 1 can adopt a common rectifying column. The raw material of the hexafluorobutadiene enters from the middle part of the pre-de-weighting tower 11, the extract at the top of the pre-de-weighting tower 1 enters one side of the adsorption device 2, and the pretreated material is extracted from the other side of the adsorption device 2. Heavy component impurities are extracted from the tower kettle of the pre-de-heavy tower 1. The operating pressure of the predegravimetric column 1 is between 50 and 120kPaA, preferably between 90 and 110 kPaA.
When the volume fraction of the hexafluorobutadiene in the hexafluorobutadiene raw material is more than or equal to 95%, the raw material pretreatment is as follows: and introducing the hexafluorobutadiene raw material into an adsorption device 2 for adsorption to obtain the pretreated material. Namely, the raw material of the hexafluorobutadiene directly enters the adsorption device 2 from one side, and the pretreated material is extracted from the other side of the adsorption device 2.
The operating pressure of the adsorption device 2 is 10-110kPaA, the operating temperature is 0-25 ℃, and the operating space velocity is 500-10000h-1. The adsorption device 2 is filled with an adsorbent, and the adsorbent includes one or more of a molecular sieve adsorbent, an activated alumina adsorbent, an activated carbon adsorbent, or a salt adsorbent.
Researches show that the commercial adsorbent is adopted, and the hexafluorobutadiene raw material is treated without special modification, so that the hexafluorobutadiene raw material can obtain good effects on certain impurities under proper operating conditions. Further research shows that various commercially available adsorbents have different adsorption selectivity for impurities in a hexafluorobutadiene raw material, most of the impurities can be removed under the reasonable collocation of the adsorbents, and the effect is not inferior to that of the adsorbent after special modification.
Different commercial adsorbents have different adsorption effects and different adsorption selectivity. The molecular sieve, especially the A-type molecular sieve, has less isomerization reaction, has particularly outstanding adsorption effect on saturated hydrofluorocarbon and good adsorption effect on water; the X type molecular sieve and the Z type molecular sieve have certain effects on halogenated hydrocarbons, but can generate severe isomerization reaction to generate hexafluoro-2-butyne and hexafluoro-cyclobutene. Sodium fluoride salts are effective in removing hydrogen fluoride. The activated alumina has wide adsorption effect on halogenated hydrocarbon, has less isomerization reaction than A-type molecular sieve, but has decomposition effect on hexafluorobutadiene when the temperature is raised, and the carbon dioxide is obviously raised. Activated carbon has a relatively poor adsorption effect, but adsorbs all impurities outside the permanent gas.
In practical application, the adsorption device 2 can be sequentially filled with 1 part of spherical sodium fluoride, 50 parts of activated carbon, 20 parts of activated alumina and 100 parts of ZSM-5 molecular sieve along the direction of the material.
Alternatively, the adsorption apparatus 2 is sequentially filled with 5 parts of spherical sodium fluoride and 150 parts of 5A molecular sieve in the material direction.
Or the adsorption device 2 is filled with 1 part of spherical sodium fluoride, 100 parts of 3A molecular sieve and 5A molecular sieve which are mixed uniformly according to the mass ratio of 1:5 along the direction of the material.
Preferably, the hexafluorobutadiene entering the adsorption unit 2, after contacting the activated alumina, contacts activated carbon.
Alternatively, the adsorption unit 2 was operated at a pressure of 10kPaA, an operating temperature of 20 ℃ and a space velocity of 500h-1。
Alternatively, in the case of using an activated alumina adsorbent, the operating temperature is 10 ℃ and the operating space velocity is 10000h-1。
When the method is used, a segmented temperature control mode can be adopted, the operating temperature of the spherical sodium fluoride is 20-25 ℃, the operating temperature of the activated carbon is 15-25 ℃, the operating temperature of the activated alumina is 5-10 ℃, and the operating temperature of the A-type molecular sieve is 15-25 ℃.
In addition, the adsorbent needs to be activated before use, otherwise the using effect and the using time of the adsorbent are reduced. And continuously heating the A-type molecular sieve for 3-6 hours in a nitrogen atmosphere at 300-400 ℃. The spherical sodium fluoride and the activated alumina are continuously heated for 1 to 4 hours in a nitrogen atmosphere at 200 to 250 ℃.
The adsorbents loaded in the adsorption apparatus 2 have fixed particle diameters for each type, and the particle diameters of different adsorbents may be the same or different.
The adsorption effect of the adsorption device 2 has obvious characteristics. The hexafluobutadiene raw material to be treated stably enters the adsorption device 2 according to a certain amount, the purity of the hexafluobutadiene at the outlet of the adsorption device 2 can reach more than 99.99 percent at first, and after the hexafluobutadiene is continuously used for a short time, the hexafluobutadiene can be quickly reduced to about 99 percent and be stable. When the adsorption is saturated, a significant increase in the impurity content is observed, at which point a regeneration treatment is required.
The regeneration of the adsorption apparatus 2 can be performed by continuously purging with dry nitrogen gas at 200 ℃ or higher for 4 hours or more. The nitrogen purging direction can be opposite to the material, and the flow of the nitrogen is not lower than 20% of the flow in normal operation.
If the purity of the hexafluorobutadiene at the outlet of the adsorption device 2 is less than 99.99%, regardless of the cost of the treatment and the stability of the process, the collection can be stopped and the adsorption device 2 can be regenerated, and then the adsorption operation can be performed in the same manner, and the cycle can also be repeated to obtain the hexafluorobutadiene with the purity of more than 99.99%. And during stable operation, the purity of the hexafluorobutadiene in the pretreated material is about 99%.
Preferably, the pretreated material is filtered before purification, and the filtering precision is 100-5000 meshes.
2. Purification of pretreated material
The purification of the pretreated material is as follows: introducing the pretreated material into a secondary light component removal tower 5 after primary light component removal and primary heavy component removal, and extracting a refined hexafluorobutadiene product from the lateral line of the secondary light component removal tower 5;
the first-stage lightness-removing is carried out in a first-stage lightness-removing tower 3, the first-stage weight-removing is carried out in a weight-removing tower 4, a cluster rectifying column is arranged in the weight-removing tower 4, and the tower kettle extract of a second-stage lightness-removing tower 5 is circularly led into the weight-removing tower 4 to remove heavy components. In the purification process, a two-stage light component removal tower is adopted to remove light components, particularly hexafluorocyclobutene and hexafluoro-2-butyne; heavy components are removed by a heavy component removing tower 4 adopting a cluster rectification technology.
As shown in fig. 2, in the purification process of the pretreated material, the pretreated material is first subjected to primary light component removal to remove light component impurities, then subjected to primary heavy component removal to remove heavy component impurities, and finally introduced into a secondary light component removal tower. The pretreated material enters from a feed inlet of a first-stage lightness-removing tower 3, the tower kettle extract of the first-stage lightness-removing tower 3 enters a feed inlet of a heavy-removing tower 4, and light component impurities are extracted from the tower top; the tower top extract of the heavy component removal tower 4 enters a feed inlet of a secondary light component removal tower 5, and the tower kettle extract of the secondary light component removal tower 5 enters a feed inlet of the heavy component removal tower 4; heavy component impurities are extracted from the tower kettle of the heavy component removal tower 4, light component impurities are extracted from the tower top of the second-stage light component removal tower 5, and a hexafluorobutadiene product is extracted from a side line extraction outlet.
Or, as shown in fig. 3, in the purification process of the pretreated material, the pretreated material is firstly subjected to primary heavy component removal to remove impurities of heavy components, then subjected to primary light component removal to remove impurities of light components, and finally introduced into a secondary light component removal tower. The pretreated material enters from a feed inlet of a heavy component removal tower 4, heavy component impurities are extracted from a tower kettle of the heavy component removal tower 4, and the extracted material at the tower top enters a feed inlet of a first-stage light component removal tower 3; the light components are extracted from the top of the first-stage lightness-removing tower 3, and the light components are extracted from the bottom of the tower and enter a feed inlet of a second-stage lightness-removing tower 5; the tower kettle extracted material of the second-stage light component removal tower 5 enters a feed inlet of the heavy component removal tower 4, the tower top of the second-stage light component removal tower 5 extracts light components, and a lateral line extraction outlet extracts a hexafluorobutadiene product.
Preferably, the height of the side draw of the secondary lightness-removing column 5 is lower than the feed inlet thereof.
The cluster rectifying column in the de-heavy tower 4 is composed of two or more sub-rectifying columns with the same diameter which are vertically arranged in parallel, each sub-rectifying column is pairwise parallel, the length is the same, and the top ends of the sub-rectifying columns are in the same horizontal plane. Preferably, the sub-rectification columns use the same packing, preferably structured packing. When the diameter of the heavy component removal column 4 exceeds 250mm, the gas-liquid distribution in the column will greatly affect the efficiency of the heavy component removal column 4.
In the heavy component removal tower 4, the upper part and the lower part of the cluster rectification column are respectively provided with a liquid phase distributor and a gas phase distributor suitable for cluster rectification, and the feed inlet of the heavy component removal tower is provided with a gas-liquid phase distributor suitable for cluster rectification.
The top pressure of the first-stage lightness-removing tower 3 is 50-250kPaA, and the reflux ratio is 4-50; the overhead pressure of the secondary light component removal tower 5 is 50-250kPaA, the reflux ratio is 50-500, the overhead pressure of the heavy component removal tower 4 is 50-250kPaA, and the reflux ratio is 0.5-5.
The column top pressure of the first-stage light ends removal column 3, the second-stage light ends removal column 5 and the heavy ends removal column 4 is preferably 70 to 200kPaA, more preferably 90 to 150kPaA, and still more preferably 95 to 120 kPaA.
In the following examples, the composition of the hexafluorobutadiene feedstock to be treated is shown in Table 1 on a volume basis.
TABLE 1 raw material composition (volume fraction)
Example 1:
pretreatment of raw materials:
the hexafluorobutadiene feed R-1 in Table 1 was processed using the scheme shown in FIG. 1. The hexafluorobutadiene raw material is sequentially treated by a pre-de-weighting tower 1 and an adsorption device 2 to obtain a pre-treated material.
The rectification column of the pre-de-weighting tower 1 is filled with SULZER CY packing. The operation pressure of the pre-de-weighting tower 1 is normal pressure, and the reflux ratio is 1. The raw material of the hexafluorobutadiene enters from the rectifying column of the pre-de-weighting tower 1 from the position 1/2 from top to bottom.
The adsorption device 2 adopts gas phase adsorption, the tower top material of the pre-de-weighting tower 1 enters from the top of the adsorption device 2, and the pretreated material is extracted from the bottom of the adsorption device 2. The adsorption device 2 is vertically arranged, and a 500-mesh filter screen is arranged at a bottom extraction port of the adsorption device.
The diameter of the adsorption device 2 is 150mm, and 50 parts of phi 5mm spherical active carbon, 10 parts of phi 4mm spherical sodium fluoride and 200 parts of phi 1mm 5A molecular sieve are sequentially filled in the adsorption device from bottom to top. The adsorbent is supported by a sieve plate with the aperture of phi 3mm, a sintered stainless steel filter screen with the thickness of 5mm is arranged between the adsorbent and the sieve plate, and the filtering precision is 100 meshes. Before use, the above adsorbents were all continuously purged with nitrogen at 350 ℃ for 3 hours.
The operating temperature of the adsorption device 2 is 10 ℃, the operating pressure is 50kPaA, and the operating space velocity is 8000h-1. The outer side of the adsorption device 2 is provided with a jacket, and the operating temperature is controlled by heat exchange of the jacket.
The material pretreated by the pretreatment module is P-1 in Table 2.
And (3) purifying the pretreated material:
the pretreated material was processed using the flow shown in FIG. 2. The material sequentially passes through a first-stage light component removal tower 3, a heavy component removal tower 4 and a second-stage light component removal tower 5 to obtain a hexafluorobutadiene product.
The feed inlet of the first-stage lightness-removing column 3 is positioned at 1/3 from top to bottom of the rectification column of the first-stage lightness-removing column 3; an upper feed port of the de-heavy column 4 is positioned at 3/4 from top to bottom of a rectification column of the de-heavy column 4, and a lower feed port is positioned at 1/2 from top to bottom of the rectification column of the de-heavy column 4; the feed inlet of the second-stage light component removing tower 5 is positioned at 1/2 from top to bottom of the rectification column of the second-stage light component removing tower 5, and the discharge outlet is positioned at 1/4 from top to bottom of the rectification column of the second-stage light component removing tower.
The de-heavy column 4 uses a cluster rectification column and is composed of 19 sub-rectification columns with the diameter of 80mm which are vertically arranged in parallel, and the distance between the centers of the cross sections of the sub-rectification columns in the radial direction is 100 mm. The upper part and the lower part of the cluster rectification column of the de-heavy tower 4 are respectively provided with a liquid phase distributor and a gas phase distributor suitable for cluster rectification, and the upper feed inlet and the lower feed inlet are both provided with a gas-liquid phase distributor suitable for cluster rectification. The rectification column of the first-stage light component removal tower 3, each sub-rectification column of the heavy component removal tower 4 and the rectification column of the second-stage light component removal tower 5 are all filled with SULZER CY filler.
The operation pressure of the first-stage light component removal tower 3, the heavy component removal tower 4 and the second-stage light component removal tower 5 is 120kPaA, 105kPaA and 95kPaA respectively, and the operation reflux ratio is 25, 2 and 100 respectively.
After purification, the resulting hexafluorobutadiene product was P-2 in Table 2.
Example 2:
pretreatment of raw materials:
the diameter of the adsorption device 2 is 200mm, and 50 parts of phi 5mm spherical active carbon, 10 parts of phi 4mm spherical sodium fluoride, 50 parts of phi 2mm 4A molecular sieve and 300 parts of phi 0.8mm 5A molecular sieve are sequentially filled in the adsorption device from bottom to top. The rest is the same as example 1.
And (3) purifying the pretreated material:
the operation pressure of the first-stage lightness-removing column 3, the second-stage lightness-removing column 4 and the second-stage lightness-removing column 5 are respectively 105kPaA, 100kPaA and 90kPaA, and the operation reflux ratio is respectively 50, 5 and 300, and the rest is the same as that of the example 1.
After purification, the resulting hexafluorobutadiene product was P-3 in Table 2.
Comparative example 1:
in the purification process, the dephlegmator 4 adopts a common rectifying column, the rest is the same as the example 1, and the obtained hexafluorobutadiene product is P-4 in the table 2.
Comparative example 2:
in the purification process, the dephlegmator 4 adopts a common rectifying column, the operation reflux ratio is 40, and the obtained hexafluorobutadiene product is P-5 in the table 2 in the same way as in the example 1.
TABLE 2 composition of the treated materials (volume fraction)
| Composition of | P-1 | P-2 | P-3 | P-4 | P-5 |
| Hexafluorobutadiene | 99.01％ | 99.996％ | 99.9991％ | 99.879％ | 99.995％ |
| Light component | 0.61％ | 0.002％ | 0.0003％ | 0.002％ | 0.002％ |
| Heavy fraction | 0.23％ | 0.001％ | 0.0005％ | 0.118％ | 0.002％ |
| Others | 0.15％ | 0.001％ | 0.0001％ | 0.001％ | 0.001％ |
As shown in Table 2, the purity of the purified product was still higher than 99.995%, although a commercially available adsorbent without special modification was used. Compared with the example 1, the comparative example 1 shows that under the same operation condition, the heavy component removing efficiency of the heavy component removing tower 4 by using the cluster rectifying column is obviously improved, and the product purity can not even reach 99.9 percent by using the common rectifying column for treatment. Comparative example 2 shows that the de-emphasis column 4 using the conventional rectification column has an extremely high energy consumption when the product purity reaches 99.995% as compared with example 1.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (10)
1. A refining method of hexafluorobutadiene is characterized by comprising the steps of raw material pretreatment and purification of pretreated materials;
the raw material pretreatment comprises an adsorption process of a hexafluorobutadiene raw material to obtain a pretreated material;
the purification of the pretreated material comprises the following steps: introducing the pretreated material into a secondary light component removal tower after primary light component removal and primary heavy component removal, and extracting a refined hexafluorobutadiene product from the lateral line of the secondary light component removal tower;
in the purification process of the pretreated material, the first-stage lightness-removing is carried out in a first-stage lightness-removing tower, the first-stage weight-removing is carried out in a weight-removing tower, a cluster rectifying column is arranged in the weight-removing tower, and the tower kettle extract of the second-stage lightness-removing tower is circularly introduced into the weight-removing tower to remove heavy components.
2. The method of claim 1, wherein the raw material of hexafluorobutadiene contains hexafluorobutadiene, a light component and a heavy component, the volume fraction of the hexafluorobutadiene is not less than 60%, the light component is an organic substance having a lower atmospheric boiling point than that of the hexafluorobutadiene contained in the raw material of the hexafluorobutadiene, and the heavy component is an organic substance having a higher atmospheric boiling point than that of the hexafluorobutadiene contained in the raw material of the hexafluorobutadiene.
3. The method for refining hexafluorobutadiene as claimed in claim 2, wherein when the volume fraction of hexafluorobutadiene in the hexafluorobutadiene raw material is 60% -95%, the raw material pretreatment is: and introducing a hexafluorobutadiene raw material into a pre-de-heavy tower to remove heavy component impurities, and introducing a tower top extract of the pre-de-heavy tower into an adsorption device for adsorption to obtain a pretreated material.
4. The method for refining hexafluorobutadiene as claimed in claim 2, wherein when the volume fraction of hexafluorobutadiene in the hexafluorobutadiene raw material is not less than 95%, the raw material pretreatment is: and introducing the hexafluorobutadiene raw material into an adsorption device for adsorption to obtain the pretreated material.
5. The method according to claim 3 or 4, wherein the adsorption apparatus is operated at a pressure of 10 to 110kPaA and at a temperature of 10 to 110kPaAThe temperature is 0-25 ℃, and the operation space velocity is 500-10000h-1。
6. The method according to claim 3 or 4, wherein the adsorption apparatus is loaded with an adsorbent comprising one or more of a molecular sieve adsorbent, an activated alumina adsorbent, an activated carbon adsorbent, or a salt adsorbent.
7. The method of claim 1, wherein in the purification of the pretreated material, the pretreated material is first subjected to a first light component removal to remove light component impurities, then subjected to a first heavy component removal to remove heavy component impurities, and finally introduced into a second light component removal tower.
8. The refining method of hexafluorobutadiene as claimed in claim 1, wherein in the purification process of the pretreated material, the pretreated material is first subjected to a first-stage heavy component removal to remove impurities of heavy components, then subjected to a first-stage light component removal to remove impurities of light components, and finally introduced into a second-stage light component removal tower.
9. The method according to claim 1, wherein the de-weighting column has a liquid phase distributor and a gas phase distributor at upper and lower portions thereof, respectively, and the de-weighting column has a gas-liquid phase distributor at a feed inlet thereof.
10. The method according to claim 1, wherein the overhead pressure of the first-stage lightness-removing column is 50 to 250kPaA, and the reflux ratio is 4 to 50; the overhead pressure of the secondary light component removal tower is 50-250kPaA, the reflux ratio is 50-500, the overhead pressure of the heavy component removal tower is 50-250kPaA, and the reflux ratio is 0.5-5.
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