JPH08309146A - Separation method for perfluorocarbon from gas current - Google Patents

Abstract

PURPOSE: To provide an effective method for removing perfluorocarbons from a gas stream by adsorption. CONSTITUTION: Prefluorocarbons are recovered from a gas stream by supplying the gas stream to an adsorption process using one or two or more energetically uniform adsorbent beds such as a high silicone adsorbent to FAU structure, a high silicone adsorbent of BEA structure and a high silicone adsorbent of MOR structure. As the adsorption process, a pressure swing adsorption or a temp. swing adsorption is preferable.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to purification of gas streams,
In particular it relates to a method of removing perfluorinated hydrocarbons from a gas stream by adsorption.

[0002]

BACKGROUND OF THE INVENTION Well fluorinated hydrocarbon derivatives (perfluorocarbons) are used worldwide in various domestic and industrial fields. As a result of such use, gaseous perfluorinated hydrocarbons are currently being released into the environment. As an example, low molecular weight perfluorocarbons have been used in the semiconductor manufacturing industry in combination with oxygen for etching silicon chips and cleaning chemical vapor deposition chambers. These steps are typically performed under vacuum. Exhaust gas from the chamber contains, in addition to perfluorocarbons, unreacted vapor deposition compounds and various reaction products such as hydrogen fluoride and nitrogen trifluoride. Since these compounds cannot be safely released into the atmosphere, exhaust gases are generally treated to destroy compounds that are considered harmful or to convert them into compounds that can be released into the atmosphere. According to one procedure, the gas stream is fed into a reactor, for example a gas reactor (manufacturer: Edwards High Vacuum Inte from BOC Group).
rnational Division (trade name: EDWARDS GR
C)), in which the constituents of the gas stream react at high temperatures and are converted into wasteable solid substances. However, perfluorocarbons are highly non-reactive and pass through the reactor unaffected. Since perfluorocarbons are non-toxic and are not considered to be harmful to the ozone layer surrounding the Earth, they are currently released into the atmosphere.

However, perfluorocarbons are believed to be global warmers because of their high degree of stability and thermal properties.
Therefore, industries around the world are currently making efforts to minimize or stop the release of perfluorinated hydrocarbons into the environment. Currently available processes for recovering these compounds from waste gases are costly and not always practical, so methods of destroying them are being considered. One method proposed to destroy is combustion. This is done by heating them to temperatures above 1000 ° C, which temperature is
It is achieved by burning hydrogen and oxygen in the presence of perfluorocarbons.

[0004]

Destruction of perfluorocarbons is not the best solution to the disposal problem.
It is expensive and incomplete combustion produces other harmful by-products. Moreover, perfluorocarbons are high value products and would be beneficially reusable if they could be recovered from the gas stream at a modest cost. The present invention provides a cost effective and efficient way to achieve this end.

[0005]

According to a broad aspect of the present invention, a gas stream is provided with one or more specific energetically homogeneous high silicon (high silicon) microporous adsorbents. And / or by passing through one or more specific energetically homogeneous mesoporous adsorbents, one or more gaseous perfluorocarbons are at least one permanent Separated from the gas stream containing gas. Perfluorocarbons are more strongly adsorbed by these adsorbents than other components of the gas stream. Perfluorocarbons are recovered from the adsorbent by conventional regeneration procedures.

The preferred adsorbent is a dealumination type Y
-Type zeolite, dealuminated beta zeolite, and dealuminated mordenite (mordenite), all of which have a silicon to aluminum ratio of 50 or more. The most preferred adsorbent is
It is a dealumination type Y zeolite having a silicon to aluminum ratio of 100 or more.

The process of the invention can be used to recover any perfluorocarbons in the gaseous or vapor state at adsorption temperatures. The present invention is particularly suitable for the recovery of saturated or ethylenically unsaturated perfluorocarbons, especially perfluorocarbons having up to 8 carbon atoms, such as perfluoromethane, perfluoroethane, perfluoroethylene, perfluorohexane, perfluorooctane. It is suitable for collecting such as.

The particular adsorption process used is not critical to the invention and in general any adsorption procedure can be used. Circulating adsorption processes are commonly used, with pressure swing adsorption (PSA) and temperature swing adsorption (TSA) cycles, or a combination thereof being preferred. Adsorption is a set of two or more adsorbent beds arranged in parallel and is non-synchronized so that when at least one bed is subjected to adsorption, another bed is regenerated. It is preferable to be operated at

In addition to the mere adsorption process as described above, the present invention can be used to modify a particular recycle process. Specific cycling processes that can incorporate the present invention include vacuum deposition, etching chamber cleaning processes, and perfluoroethylene polymerization processes.

In cleaning the deposition and etching chambers, the chamber containing the deposit or etching chemical deposit is cleaned by introducing perfluorocarbon and oxygen into the chamber under plasma conditions. Perfluorocarbons and oxygen react with the deposits to form various gaseous products. A gas mixture consisting of reaction products, unreacted vapor deposition chemistry, perfluorocarbons, and oxygen is removed from the vapor deposition chamber (preferably by evacuation), optionally diluted with nitrogen or argon, and then passed through the reactor at elevated temperature. . This transforms the vapor deposition chemistry into a harmless solid. Perfluorocarbons are unchanged in the reactor, but are removed from the gas reactor effluent by the adsorption process described above and recycled to the deposition or etching chambers or stored for future use. Perfluorocarbons, if you need to increase their purity,
It can be subjected to further purification steps such as condensation and cryogenic distillation.

In the polymerization of perfluoroethylene,
Perfluoroethylene polymerizes in the reactor, which results in a mixed product of polymer and unreacted monomer. Unreacted monomers are removed from the mixed product by stripping, preferably with an inert gas. The stripped monomer is then subjected to the adsorption step described above, which adsorbs perfluoroethylene. After being desorbed from the adsorption bed, perfluoroethylene is recycled to the polymerization reactor, sent to storage, or disposed of.

[0012]

Preferred Modes for Carrying Out the Invention Perfluorocarbons are separated from one or more permanent gases by the process of the present invention. For purposes of this invention, permanent gases include nitrogen, oxygen, argon, helium, neon, krypton, xenon, hydrogen, and carbon monoxide. The present invention is particularly suitable for separating perfluorocarbons from nitrogen, oxygen, argon, and mixtures thereof.

Adsorbents that can be used in the present invention include:
There are certain energetically homogeneous materials that are microporous and mesoporous materials having a pore size of at least about 4.5 Angstrom units. For purposes of this description, microporous material is defined as a material having an average pore size of less than about 20 Angstrom units, and mesoporous material has an average pore size of about 20 to about. Defined as a substance in the range of 500 Angstrom units. In an energetically homogeneous adsorbent, the adsorption energies at all adsorption sites are substantially equal. This definition means that the experimentally measurable heat of adsorption is substantially constant, even when the concentration of the adsorbed compound changes. As used herein, "substantially constant heat of adsorption" means that the heat of adsorption of the substance does not change above about 10%.

Suitable microporous adsorbents include high silicon modified FAU structural class zeolites, such as dealuminated Y type; high silicon modified BEA structural class zeolites, such as dealuminated type. Beta-type zeolite; and high-silicon modified MOR structural class
Zeolites, for example dealuminated mordenite,
And carbon molecular sieves (CMS) having a pore size of at least about 4.5 Angstrom units.

As used herein, "high silicon (sil
The term "icon-rich)" means that the molecular sieve has a silicon to aluminum ratio of greater than or equal to about 50. In a most preferred embodiment, the molecular sieve has a silicon to aluminum ratio of greater than or equal to about 100: 1. High silicon molecular sieves can be produced, for example, by direct synthesis or by dealumination of the desired class of molecular sieves.High silicon molecular sieves and methods for their preparation are well known, and Structure and method of manufacture does not form any part of the present invention.

Suitable mesoporous adsorbents include polymeric carbonaceous adsorbents such as partially pyrolyzed (carbonized) sulfonated styrene-divinylbenzene copolymers (eg Rohm).
and Haas Company under the trademark Ambersorb); and M41S structural class mesoporous silicates.

The perfluorocarbons which can be separated by the process according to the invention are usually in gaseous form, ie at ambient temperature and atmospheric pressure, or at the temperature and pressure at which the adsorption step is carried out. It is of steam quality. "Perfluorinated hydrocarbons"
The term means an aliphatic hydrocarbon derivative in which all hydrogen atoms have been replaced by fluorine atoms. Included within this class of compounds are saturated and ethylenically unsaturated perfluorocarbons having a boiling point of about 100 ° C. or lower, including perfluorocarbons having 8 or fewer carbon atoms. Representative examples of perfluorocarbons that can be recovered by the process of the present invention include perfluoromethane, perfluoroethane, perfluoropropane, perfluorohexane, perfluorooctane, perfluoroethylene and the like.

For a better understanding of the present invention, reference will be made to the accompanying drawings. In the drawings, the same reference numbers indicate the same or similar components of the device. Auxiliary devices that are not necessary for an understanding of the invention, such as compressors, heat exchangers, valves etc., have been omitted from the drawings to simplify the description of the invention.

Referring to FIG. 1, A is a perfluorocarbon storage container, B is one or a set of vacuum deposition chambers or etching chambers, C is a vacuum means, D is a reactor, and E is an adsorption device. The details of construction and operation of these units are well known and they do not form any part of the present invention.

Perfluorocarbon and oxygen are supplied to chamber B through lines 2 and 4, respectively, and the chamber is evacuated through line 6. Line 6 connects chamber B to the inlet of vacuum means C. The vacuum means C is typically a vacuum pump. The vacuum means C is connected at its terminal end to the reactor D via line 10. Reactor D comprises one or more substances that react with the components of the gaseous process stream and means (not shown) for heating the gas reaction column to the desired reaction temperature. There is. The details of the gas reaction column D do not form any part of the invention and therefore they are not revealed in this description. The gas reaction column D is connected at its outlet end to the unit E by a line 12.

The unit E includes a waste gas discharge line 14
And a perfluorocarbon discharge line 16 is provided. In the illustrated embodiment, the line 16 is connected to a perfluorocarbon recycle line 18 (which is provided to return the purified perfluorocarbon to the vessel A) and a perfluorocarbon discharge line 20.

If desired, various gas treatment units,
For example, a filter or solvent wash scrubber may be placed between units C and D of the device, units D and E, or line 14 to remove particulate matter and soluble components from the device. However, they are not shown because they are not important to the invention.

The main purpose of unit E is to separate perfluorocarbons from the gaseous effluent from gas reaction column D. Unit E is typically a pressure swing adsorber or a temperature swing adsorber, preferably two or more static packed with one or more energetic homogeneous molecular sieve adsorbents of the types described above. It consists of a laid floor. The beds are generally arranged in parallel and arranged to operate in a cyclic process consisting of adsorption and desorption. As is normally done, the device in which the adsorption takes place consists of two or more non-synchronized adsorbent beds, when one or more adsorbent beds are operating during the adsorption phase of the cycle:
One or more other adsorbent beds are regenerated.

In practicing the method of the invention shown in FIG. 1, perfluorocarbon and oxygen are introduced through lines 2 and 4, respectively, into chamber B of the apparatus where the chemical vapor deposition or etching operation has just been completed. . The chamber contains a variety of chemical waste vapor deposition materials that need to be removed from the chamber so that the chamber can be prepared for subsequent chemical vapor deposition or etching operations. Perfluorocarbons and oxygen come into contact with waste evaporation materials and react with them,
Gaseous waste products are produced. The gaseous product, together with unreacted perfluorocarbon and oxygen, is removed from the deposition chamber by suction created by the vacuum means C. The gaseous product and unreacted oxygen form a flammable mixture, so to prevent premature combustion of the product gas,
An inert gas such as nitrogen, argon, carbon dioxide is introduced into line 6 through line 8. The gas mixture passing through line 10 is then introduced into reactor D,
In which the mixture is heated to above about 600 ° C. The various components of the heated mixture come into contact with the reactants in the tower,
The product can be safely discharged into the environment or can be easily recovered by the subsequent chemical treatment. Line 1
Unreacted perfluorocarbons in 0 pass through unit D unchanged. The effluent gas from the gas reaction column then enters unit E, in which it undergoes gas adsorption.

The adsorption process consists of repeating the adsorption step and the bed regeneration step. In a preferred embodiment, the adsorption process is pressure swing adsorption, temperature swing adsorption, or a combination of the two, with the particular adsorption method being determined by the chemical composition of the process gas. Although the particular conditions under which the adsorption process is carried out determine the efficiency of the adsorption process, they do not form part of the present invention. These conditions are well known to those skilled in the field of gas adsorption processes and any combination of widely varying operating conditions used in adsorption processes can be used in the method of the present invention.

Generally, the adsorption step is usually carried out at a temperature in the range of about -100 ° C or lower to about + 100 ° C and an absolute pressure in the range of about 0.5 to about 20 bar, preferably about 15 ° C. To absolute pressures in the range of about 1 to about 10 bar. The lower the temperature, the better the separation performance of the adsorbent. During the adsorption step of the process, feed gas is introduced into the adsorber,
It flows through each of the beds in the adsorption stage of the cycle. Perfluorocarbons are adsorbed on the adsorbent as the gas flows through the bed. When the adsorption process progresses,
The adsorption front formed at the front end of the adsorbed perfluorocarbon advances in the direction of the unadsorbed gas outlet. The remainder of the gas stream passes through the bed and exits unit E through line 14 as waste gas. Waste gas may be vented to the atmosphere if it contains no components harmful to the environment. Alternatively, it may be sent to downstream equipment for further processing. When the adsorption front reaches the desired position in the adsorption bed, the flow of feed gas into the bed is stopped. This marks the end of the adsorption stage of the separation process.

The bed which has completed the adsorption stage is then subjected to regeneration. The conditions under which the bed regeneration is carried out are likewise not critical for successful results in the practice of the invention. P
Regeneration of the SA bed can be carried out at absolute pressures below about 100 mbar, but it is about 100 to about 100
It is usually done at absolute pressures in the range of 0 mbar. TSA
Bed regeneration is carried out by heating the adsorbent to a temperature above the temperature at which the adsorption step is carried out, which temperature is typically in the range of about 0 to about 200 ° C, preferably about 20 to about The temperature is in the range of 150 ° C. Desorption can be performed by a heater and / or by passing steam or heated inert gas through the bed. During the regeneration step of the TSA cycle, the pressure in the adsorption vessel can be as high as or lower than the pressure maintained in the vessel during the adsorption step. It is often preferred to carry out the temperature swing process at or near atmospheric pressure. When a combination of pressure swing adsorption cycle and temperature swing adsorption cycle is used,
During the bed regeneration process, the temperature is higher and the pressure is lower than when the cycle is in the adsorption process.

During regeneration, the perfluorocarbon is desorbed from unit E through line 16. The recovered perfluorocarbon can be returned to storage vessel A through line 18, if it is of a purity suitable for recycling to the device. Alternatively, it can be discharged from the device through line 20 for further purification.

In the embodiment of the present invention shown in FIG. 2, F is a polymerization reactor, G is a polymer recovery unit, and H is a tetrafluoroethylene adsorption device. All of these units and devices are well known and the specific details of their construction and operation do not form part of the present invention.

The reactor F is provided with a monomer supply line 30 and a polymer discharge line 32. Reactor F is a typical batch or continuous tetrafluoroethylene polymerization reactor, which has all the standard features needed for the polymerization of tetrafluoroethylene monomer, such as catalyst feed line, polymerization. Means for agitating the contents of the reactor during operation, means for heating the contents of the reactor, etc. are provided, none of which are shown.

The polymer discharge line 32 is connected to the inlet of the polymer recovery unit G. Unit G is typically a stripping unit, which is accompanied by a stripping gas inlet line 34, a polymer recovery line 36, and a stripped gas outlet line 38. Line 38 is connected to the inlet of adsorption unit H, which is similar or identical to unit E of FIG.
A waste gas line 40 and a tetrafluoroethylene recovery line 42 are attached to the unit H.

In practicing the invention with the apparatus of FIG. 2, tetrafluoroethylene and other desired additives, such as catalysts and polymer modifiers, are added to reactor F through line 30 or another feed line. Introduced in. The polymerization can be carried out batchwise or continuously in the liquid or gas phase. The mixture of polymer product and unreacted monomer is withdrawn from reactor F via line 32 and introduced into polymer recovery unit G. In unit G, the polymer is stripped with an inert gas such as nitrogen or argon, thereby stripping unreacted monomer from the polymer. The stripped polymer is removed from unit G and sent to a further processing unit downstream of the apparatus of FIG. 2 where the stripped gas stream containing stripping gas and unreacted tetrafluoroethylene is in line 38. Is discharged from the unit G through the and then introduced into the adsorption recovery unit H. In unit H, unreacted tetrafluoroethylene is adsorbed from the feed stream in the manner described above for the apparatus of FIG. The adsorbed tetrafluoroethylene is then desorbed from the adsorbent and recycled to reactor F through line 42 if the polymerization process is continuous, or if the polymerization process is batch type. Delivered to tetrafluoroethylene storage container.

[0033]

The present invention is further described by the following examples, in which parts, percentages, and ratios, unless otherwise indicated, are:
It is expressed on a volume basis.

Example 1 Diameter 1/4 inch (6.35 mm) and length 2 feet (6
A 1 cm) gas chromatographic column was packed with extruded pellets of dealuminated Y-zeolite (commercially available from Degussa AG under the trademark Degussa Wessalith DAY-type zeolite). Helium as a carrier gas was passed through the column at a flow rate of 30 ml / min using the column maintained at a temperature of 0 ° C.
A sample of a gas mixture consisting of nitrogen, 1% tetrafluoromethane (CF ₄ ) and 2% hexafluoroethane (C ₂ F ₆ ) was injected into a carrier gas and passed through a column packed with an adsorbent. did. Table 1 shows the elution time of each component.
The CF ₄ / N ₂ and C ₂ F ₆ / N ₂ separation factors for each test were measured and are also shown in Table 1. The above procedure was repeated at temperatures of 20 ° C and 30 ° C. The results of these tests are also shown in Table 1.

[0035]

[Table 1]

Example 2 In this example, a series of pressure swing adsorption tests were conducted using various nitrogen-hexafluoroethane (C ₂ F ₆ ) gas mixtures as the feed. The feed stream for tests 1, 2, 3, and 5 consisted of nitrogen and C ₂ F ₆ . The feed stream for test 4 was 4% in addition to nitrogen and C ₂ F _6.
Contains oxygen. All tests are 20 inches long (50.
8 cm) and a 1.25 inch (31.8 mm) diameter pair of cylindrical adsorption vessels. In tests 1 to 4, the adsorption beds were packed with Degussa Wessalith DAY type zeolite and in tests 5 the beds were packed with Ambersorb 563 ™ adsorbent. The adsorption vessels were operated asynchronously to each other with a 30 minute adsorption cycle. This cycle consisted of feed pressurization = 3 seconds; adsorption = 447 seconds; bed equalization, decompression = 3 seconds; bed evacuation = 447 seconds; bed equalization, repressurization = 3 seconds; product Backfill = 3 seconds; Floor equalization was forward (top-to-top) in tests 1, 2, and 5 and floor equalization was backward (top-to-botto) in tests 3 and 4.
m) I went. Adsorption was carried out at a pressure of 3.77 bar and at various temperatures and flow rates shown in Table 2. During the evacuation process, the adsorption vessel was evacuated by a vacuum pump to an absolute pressure of 100 mbar. The adsorption temperature, the supply flow rate (liter / minute), the concentration of hexafluoroethane in the supply gas stream and the product gas stream, and the recovery rate of C ₂ F ₆ are shown in Table 2 (Tests 1 to 4).

[0037]

[Table 2]

Although the present invention has been described with reference to particular experiments in particular embodiments, it is believed that the embodiments are merely illustrative of the invention and that various modifications are possible. For example,
The adsorbent bed may consist of a mixture of two or more adsorbents of the type described above, or two or more adsorbents may be used in series. Further, the present invention may be used solely as an adsorption process or as part of a vapor deposition chamber cleaning or etching process.
Alternatively, it can be carried out as part of another process desired to recover perfluorocarbons. For example, the present invention may be used to recover perfluorocarbons formed during aluminum refining operations, to separate perfluorocarbons from a laser gas, or to recover cooling gas. Can be used. The scope of the invention is limited only by the claims.

[Brief description of drawings]

1 is a block diagram illustrating one embodiment of an apparatus for performing the method of the present invention.

FIG. 2 is a block diagram showing another embodiment of the apparatus for carrying out the method of the present invention.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Ramakrishnan Ramachandran New Jersey 07401, Allendale, Hillside Avenue 232 (72) Inventor Martin Bureau New Jersey 07920-3043, Basking Ridge, James Town Road 54 (72) Inventor Theodor Earl Garica, NJ 08826, Glen Gardner, Tall Timber Drive 14

Claims (25)

[Claims] 1. A perfluorinated hydrocarbon and one or two kinds.
A method for separating at least one gaseous perfluorinated hydrocarbon from a gas stream containing one or more permanent gases, the gas stream comprising a high silicon adsorbent of FAU structure, high silicon of BEA structure. An adsorbent, a high silicon adsorbent with a MOR structure, a carbon molecular sieve having a pore size of at least 4.5 Angstrom units,
Pass through an adsorbent selected from carbonized sulfonated styrene-divinylbenzene copolymers, mesoporous silicates of the M41S structural class, and mixtures thereof, thereby adsorbing the at least one perfluorinated hydrocarbon from the gas stream. how to. 2. The method of claim 1, wherein the at least one gaseous perfluorinated hydrocarbon has 1 to 8 carbon atoms. 3. The method of claim 2, wherein the at least one gaseous perfluorinated hydrocarbon is selected from tetrafluoromethane, hexafluoroethane, octofluoropropane, tetrafluoroethylene, and mixtures thereof. Method. 4. The one or more permanent gases are,
The method of claim 1 selected from nitrogen, oxygen, argon, and mixtures thereof. 5. The one or more permanent gases are
The method of claim 3, wherein the method is selected from nitrogen, oxygen, argon, and mixtures thereof. 6. The method of claim 1, wherein the adsorbent is a high silicon adsorbent of FAU structure. 7. The method according to claim 6, wherein the adsorbent is a dealuminated Y-type zeolite. 8. The method of claim 7, wherein the dealuminated Y-zeolite has a silicon to aluminum ratio of at least about 100. 9. A circulating adsorption process for separating one or more gaseous perfluorocarbons from a nitrogen-containing gas stream comprising: (a) said gas stream having a FAU structure; High Silicon Adsorbent, BEA Structure High Silicon Adsorbent, MOR Structure High Silicon Adsorbent, Carbon Molecular Sieve with Pore Diameter of at least 4.5 Angstrom Units, Carbonized Sulfonated Styrene
-Passing through at least one adsorbent bed selected from divinylbenzene copolymers, mesoporous silicates of the M41S structural class, and mixtures thereof, whereby said one or more gaseous perfluorocarbons are A method comprising adsorbing from a gas stream and then (b) desorbing the adsorbed one or more gaseous perfluorocarbons from the adsorbent. 10. The method of claim 9, wherein the circulating adsorption method is selected from a pressure swing adsorption method, a temperature swing adsorption method, and a combination thereof. 11. The adsorption step of the circulating adsorption method comprises: a temperature in the range of about -100 to about 100 ° C .;
Method according to claim 9, carried out at an absolute pressure in the range of 20 bar. 12. The method of claim 9, wherein the one or more gaseous perfluorocarbons are selected from tetrafluoromethane, hexafluoroethane, octofluoropropane, tetrafluoroethylene, and mixtures thereof. The method described. 13. The method according to claim 12, wherein the adsorbent is a dealuminated Y-type zeolite. 14. The method of claim 13, wherein the dealuminated Y-zeolite has a silicon to aluminum ratio of at least about 100. 15. A method of cleaning a chamber containing chemical residues by silicon vapor treatment, comprising: (a) passing a gaseous perfluorocarbon and oxygen through the chamber, thereby producing a reaction product and oxygen. And (b) introducing into the gas mixture an inert gas selected from nitrogen, argon, and mixtures thereof; and (c) adding the gas mixture to the gas mixture. Passing through a reactor containing a compound that reacts with the reaction product, thereby substantially removing the reaction product from the gas mixture, but in this case having no significant effect on the perfluorocarbon And (d) adding the substantially reaction product-free gas mixture to a silicon adsorbent having a FAU structure and a silicon adsorbent having a BEA structure. Agents, high silicon adsorbents of MOR structure, carbon molecular sieves with pore sizes of at least 4.5 Angstrom units, carbonized sulfonated styrene-divinylbenzene copolymers, mesoporous silicates of the M41S structural class, and mixtures thereof. A cyclic adsorption step using at least one selected adsorbent bed, thereby separating said perfluorocarbon from said substantially reaction product-free gas mixture; a method comprising each of these steps. 16. The method of claim 15, further comprising recirculating the separated perfluorocarbon to the chamber. 17. The method further comprising scrubbing the gas mixture with a solvent for at least one reaction product contained in the gas mixture prior to step (c). The method described in. 18. The method according to claim 15, wherein the chamber is a vapor deposition chamber or a silicon chip etching chamber. 19. The method according to claim 15, wherein the adsorbent is a dealuminated Y-zeolite. 20. The method of claim 19, wherein the dealumination-type Y zeolite has a silicon to aluminum ratio of at least about 100. 21. A method of polymerizing tetrafluoroethylene comprising: (a) contacting tetrafluoroethylene with a catalyst in a polymerization reactor, thereby comprising polytetrafluoroethylene and unreacted tetrafluoroethylene. (B) stripping the product mixture with an inert gas, thereby forming a stripped gas mixture comprising stripping gas and unreacted tetrafluoroethylene; and (b) forming a product mixture; c) adding the above stripped gas mixture to FA
U structure high silicon adsorbent, BEA structure high silicon adsorbent, MOR structure high silicon adsorbent, at least 4.
Circular with at least one adsorbent bed selected from carbon molecular sieves having a pore size of 5 Angstrom units, carbonized sulfonated styrene-divinylbenzene copolymers, mesoporous silicates of the M41S structural class, and mixtures thereof. Of the stripped gas mixture to separate unreacted tetrafluoroethylene; a process comprising each of these steps. 22. The method of claim 21, further comprising recycling unreacted tetrafluoroethylene from step (c) to the polymerization reactor. 23. The method of claim 21, wherein the adsorbent is dealuminated Y-zeolite. 24. The method of claim 23, wherein the dealuminated Y-zeolite has a silicon to aluminum ratio of at least about 100. 25. The method of claim 21, wherein the inert gas is selected from nitrogen, argon, and mixtures thereof.