JP3853397B2 - Process for producing pentafluoroethane and composition suitable for conversion to pentafluoroethane - Google Patents

Description

【００６１】
生成物ガス中にはクロロペンタラフルオロエタンは認められず、従ってこの実施例はCFC 114/114aがHCFC 124出発原料中に存在しない場合にはクロロペンタフルオロエタンの生成が排除されることを例示している。
【００６２】
実施例２
クロミア触媒(1g)をインコネル製反応器（直径1/4インチ）に充填した。HF(60ml/分)を340℃で16時間、触媒上に通送したあ。塩素流とHCFC 133a流を以下に示す流率で導入した。反応器からのオフガス組成をガスクロマトグラフィーにより監視した。その結果を表２に示す。
【００６３】

【００６４】
実施例３ 124、114 及び114aを含有する混合物からのHCFC 124の精製
本実施例はHFA 125からCFC 115を分離する場合と比較した、蒸留によるHCFC124からのCFC 114/114aの分離の容易性を例示する。
この実施例では組成は全てモル％で示されている。
容量250mlのフラスコ、５理論棚段真空ジャケット付充填塔(5 theoreticalstage vacuum jacketed packed column)（ラシッヒリングを充填）、コンデンサー及び取出し制御器(take-off controller)からなる反応装置(still)に90モル％の124、4.5モル％の114/114a及び5.5モル％の133aの混合物150gを導入した。充 填塔を大気圧下での全還流(total reflux)下で約-12Cに安定化した。平衡化した後、蒸気サンプルを塔頂から採取した；ガスクロマトグラフィー分析の結果はこのサンプルは下記の組成を有することを示した：
124-99.4
133a-0.15
114/114a-0.08
【００６５】
当初の原料混合物の約半分が蒸留されるまで5:1の還流比で蒸留を継続した。 蒸留塔の頂部から蒸気のサンプルを採取した；ガスクロマトグラフィー分析の結果はこのサンプルは下記の組成を有することを示した：
HCFC 124-99.88
CFC 114/114a-検出されない
HCFC 133a-検出されない
【００６６】
比較例１
実施例３で使用したものと同一の装置を使用してかつHFA 125-98.2％とCFC 115-1.8％との混合物を使用して、実施例３を繰返した。全還流下で約-50Cに平 衡化した後、蒸気サンプルを採取した；この蒸気サンプルは下記の組成を有していた：
HFA 125-98.0
CFC 115-2.0
原料混合物の約半分が蒸留されるまで5:1の還流比で蒸留を継続した後には、 蒸留物は下記の組成を有していた：
HFA 125-98.3
CFC 115-1.7
【図面の簡単な説明】
【図１】２個の反応器を使用する本発明の態様であって、工程(i)が1,1,1,2-テトラフ ロロエタンの塩素化であり、２個の反応器が直列に配置されている場合の概略フローダイグラムである。
【図２】２個の反応器を使用する本発明の態様であって、工程(i)が1,1,1,2-テトラフ ロロエタンの塩素化であり、２個の反応器が並列に配置されている場合の概略フローダイグラムである。
【図３】工程(i)がパークロロエチレンの弗化水素処理であり、工程(i)及び(iii)が単 一の反応器で行われそして水性スクラビングを使用して塩化水素を除去する場合の本発明の態様を示す概略フローダイグラムである。
【図４】２個の反応器を使用する本発明の態様であって、工程(i)がパークロロエチレ ンの弗化水素処理であり、２個の反応器が並列に配置されている場合を示す概略フローダイグラムである。
【図５】２個の反応器を使用する本発明の態様であって、工程(i)がパークロロエチレ ンの弗化水素処理であり、２個の反応器が直列に配置されている場合の概略フローダイグラムである。
【図６】２個の反応器を使用する本発明の態様であって、工程(i)がパークロロエチレ ンの弗化水素処理であり、２個の反応器が直列に配置されている場合の概略フローダイグラムである。
【図７】工程(i)がパークロロエチレンの弗化水素処理であり、工程(i)及び(iii)が単 一の反応器で行われる場合の本発明の態様を示す概略フローダイグラムである。[0001]
[Industrial application fields]
The present invention relates to a method for producing pentafluoroethane.
[0002]
[Prior art and problems to be solved]
Pentafluoroethane (HFA 125) has been proposed as a component of non-ozone-depleting refrigerant formulations in a number of applications where chlorofluorocarbons and fluorofluorocarbons are used, particularly low temperature cooling; Pentafluoroethane is a suitable substitute for various chlorofluorocarbons and hydrochlorofluorocarbons, difluoromethane HFA 32, 1,1,1-trifluoroethane HFA 143a and / or 1,1,1,2-tetrafluoro It has been proposed as a component of blends with other hydrofluoroalkanes such as ethane HFA 134a, in particular the blend of refrigerant blends R502 and chlorodifluoromethane HCFC 22.
[0003]
Recently, a number of methods for the production of pentafluoroethane have been proposed, including the hydrogenation of chloropentafluoroethane CFC 115 and the hydrofluorination of perchloroethylene, for example. it can .
[0004]
The hydrogenation of chloropentafluoroethane is typically carried out under conditions such that the conversion of chloropentafluoroethane is incomplete and therefore pentafluoroethane contaminated with chloropentafluoroethane is produced. Chloropentafluoroethane and pentafluoroethane have very close boiling points, i.e., boiling points of -38 ° C and -48 ° C, respectively, and form a minimum boiling azeotrope, and therefore It is difficult to separate by conventional methods such as distillation, so that the resulting pentafluoroethane is acceptable because of the presence of significant amounts of CFC 115, for example as much as 5% CFC 115. May have less low purity.
[0005]
In the hydrofluoric treatment of perchlorethylene, it is necessary to carry out a large number of halogen exchange reactions in order to obtain pentafluoroethane, so that productivity is significantly limited. In addition, the catalysts typically used in hydrochlorination of perchlorethylene are highly coke and are thus deactivated by the successive halogen exchange reactions that occur.
[0006]
In addition to the continuous halogen exchange reaction that produces pentafluoroethane via tetrachlorofluoroethane HCFC 121, trichlorodifluoroethane HCFC 122, dichlorotrifluoroethane HCFC 123, and chlorotetrafluoroethane HCFC 124, under certain conditions and In the presence of certain catalysts, chloropentafluoroethane is converted via pentachlorofluoroethane CFC 111, tetrachlorodifluoroethane CFC 112, trichlorotrifluoroethane (CFC 113 and 113a) and dichlorotetrafluoroethane (CFC 114 and 114a). The continuous reaction that occurs occurs, resulting in a significant amount of chloropentafluoroethane contaminating the pentafluoroethane.
[0007]
Recently, much attention has been directed to the satisfactory separation of chloropentafluoroethane from pentafluoroethane. That is, for example, U.S. Pat. However, both of these methods are directed to removing chloropentafluoroethane from pentafluoroethane.
[0008]
In contrast, now the inventor can substantially reduce or even eliminate the production of chloropentafluoroethane, thus reducing the problem in separating chloropentafluoroethane from pentafluoroethane? Alternatively, a process for producing pentafluoroethane has been developed that can even be completely eliminated.
[0009]
Configuration and effect of the invention
Thus, according to the present invention, the formula C₂Cl_{x + 1}F_yOf formula C₂HCl_xF_y(I) producing a composition comprising a compound of the formula: wherein x = 1,2 or 3 and y = 2,3 or 4 provided that x + y is 5 , Formula C₂HCl_xF_yA compound of formula C₂Cl_{x + 1}F_yStep (ii) and separation from the compound of formula C₂HCl_xF_yThere is provided a process for producing pentafluoroethane, which comprises the step (iii) of producing a pentafluoroethane by contacting the compound with hydrogen fluoride in the presence of a fluorination catalyst.
[0010]
In many embodiments of the present invention, steps (i), (ii) and (iii) are performed in the order described above, which comprises pentafluoroethane containing low levels of chloropentafluoroethane (described below). Steps (i), (ii) and (iii) may be performed in a different order; for example, in particular, step (iii) may be of formula C₂Cl_{x + 1}F_yIs carried out under conditions where the conversion of the compound to chloropentafluoroethane is low, such as about 50% or less, preferably 25% or less, step (ii) is replaced by step (i) And after (iii).
[0011]
In step (i) of the process of the invention, the composition is chlorinated or fluorinated with haloethene such as perfluoroethylene, trifluoroethylene, chlorodifluoroethylene or dichlorofluoroethylene or hydrohaloethane such as tetrafluoroethane or chlorotrifluoroethane. It can be produced by hydrogenation treatment.
[0012]
In another preferred embodiment of the present invention ((A) and (B)) (described in detail later), step (i) of the process of the present invention comprises (A) trichlorethylene or formula C₂H₂X_FourChlorinating compounds such as tetrachloroethane, tetrafluoroethane or chlorotrifluoroethane (wherein X is fluorine or chlorine) or (B) perhaloethylene or pentahaloethane in liquid or gas phase And contacting with hydrogen fluoride in the presence of a fluorination catalyst.
[0013]
The process of the present invention is advantageously carried out as a continuous process in which the product stream from step (iii) is conveniently treated by distillation to give unconverted Formula C₂HCl_xF_yThe compound of formula C is isolated from pentafluoroethane and unconverted.₂HCl_xF_yIs recycled to step (i) or step (iii), preferably step (i). Further, the product stream from step (iii) is of formula C₂Cl_{x + 1}F_yIn which case the recycle stream is present in the recycle stream₂HCl_xF_yCompound of formula C₂Cl_{x + 1}F_y15% by weight or less, more preferably 10% by weight or less, in particular 5% by weight or less, based on the total weight of the compounds of formula C₂Cl_{x + 1}F_yIt is preferable that the compound is contained.
[0014]
The composition formed in step (i) of the method of the invention has a single formula C₂Cl_{x + 1}F_yA single formula C contaminated with₂HCl_xF_yFor example, chlorotetrafluoroethane mixed with dichlorotetrafluoroethane, dichlorotrifluoroethane mixed with trichlorotrifluoroethane, or trichlorodifluoroethane mixed with tetrachlorodifluoroethane. Usually, the raw material composition is used in particular when the raw material composition is produced by one of the alternative preferred embodiments (A) or (B) in step (i) of the method of the present invention. It can consist of more composition, or it can be formula C₂Cl_{x + 1}F_yA compound of formula C in which two or more of the compounds are mixed, or even if all of them are mixed₂HCl_xF_yThe composition may consist of all of the compounds. However, the composition usually consists of at least chlorotetrafluoroethane and dichlorotetrafluoroethane, and a particularly preferred operation to be performed in step (ii) of the method of the present invention is to separate dichlorotetrafluoroethane from chlorotetrafluoroethane. It is to be.
[0015]
The composition which is the product of step (i) of the method of the present invention is produced by the formula C₂Cl_{x + 1}F_yCompound of formula C₂HCl_xF_yTypically from about 0.1 to about 20 weight percent, more typically from about 0.5 to about 15 weight percent of formula C, based on the total weight of the compounds of₂Cl_{x + 1}F_yContaining the compound. The process of step (i) is a compound of formula C wherein the composition that is the product formed in step (i) is produced.₂Cl_{x + 1}F_yCompound of formula C₂HCl_xF_yAbout 0.5 to about 10% by weight of formula C, based on the total weight of the compound of₂Cl_{x + 1}F_yIt is preferable to carry out so that this compound may be contained. The composition which is the product of step (i) also contains unconverted starting material, by-product hydrogen chloride and a small amount of other by-products depending on the particular process used in step (i). .
[0016]
According to the method of the present invention, the formula C₂HCl_xF_yCompounds, especially chlorotetrafluoroethane (HCFC 124 and 124a, boiling point; 11.0 ° C. ± 1.0 ° C. depending on the type of isomer) and dichlorotrifluoroethane (HCFC 123, 123a and 123b, boiling point; isomer) From 27.5 ° C ± 1.0 ° C depending on the type of₂Cl_{x + 1}F_yIn particular, dichlorotetrafluoroethane (CFC 114 and 114a, boiling point; 3.3 ° C ± 0.3 ° C depending on the type of isomer) and trichlorotrifluoroethane (CFC 113 and 113a, boiling point; type of isomer) (46.6 ° C ± 1.0 ° C) is effectively separated accordingly, so there is a substantial advantage. Separation step (ii) is a compound of formula C present in the composition produced in step (i).₂Cl_{x + 1}F_yAt least 50%, more preferably at least 75%, in particular at least 95% by weight of the compound of formula C₂HCl_xF_yIt is preferable to be carried out so as to be separated from the compound.
[0017]
Thus, according to the method of the present invention, the chlorofluorocarbon producing chloropentafluoroethane is removed or substantially removed before the reaction step in which chloropentafluoroethane is produced unless the chlorofluorocarbon is removed. To decrease. Separation step (ii) comprises formula C recovered by separation and fed to step (iii) of the process of the invention.₂HCl_xF_yIs less than 10% by weight, preferably less than 5% by weight, more preferably less than 2% by weight, in particular less than 1% by weight of formula C₂Cl_{x + 1}F_yIt can be carried out to contain In the embodiment of the present invention in which step (i) of the method of the present invention comprises one of the preferred embodiments (A) or (B) for step (i), step (i) is particularly preferred (B ) Or consisting of chlorination of 1,1,1,2-tetrafluoroethane, the separation of dichlorotetrafluoroethane from chlorotetrafluoroethane should be essentially achieved, and this separation operation The chlorotetrafluoroethane recovered and fed to step (iii) of the process of the present invention is 2 wt% or less of dichlorotetrafluoroethane, more preferably 1.0 wt% or less, especially 0.5 wt% or less of dichlorotetrafluoroethane. It preferably contains ethane. CFCs, especially trichlorotrifluoroethane and dichlorotetrafluoroethane, are effectively removed from the process of the present invention before a substantial amount of chloropentafluoroethane is produced, resulting in the production of the process of the present invention. The amount of chloropentafluoroethane in the pentafluoroethane prior to the special purification step performed to remove chloropentafluoroethane from the pentafluoroethane is the amount of chloropentafluoroethane produced. Based on the total weight of ethane and pentafluoroethane, it can be as low as 5 wt% or less, preferably 3 wt% or less, more preferably 2 wt% or less, especially 1 wt% or less.
[0018]
Step (i) is trichlorethylene or formula C₂H₂X_FourIn a preferred embodiment (A) of the invention consisting of chlorination of a compound of the formula (wherein X is fluorine or chlorine), the starting material is tetrachloroethane, tetrafluoroethane or chlorotrifluoroethane, in particular The starting material is preferably 1,1,1,2-tetrafluoroethane.
[0019]
Chlorination techniques are well known to those skilled in the art, and any such chlorination technique may be used in step (i) of the process of the present invention. For example, chlorination can be carried out in the liquid phase or in the gas phase, and chlorination can be activated photochemically, catalytically or thermally.
[0020]
When the starting material is 1,1,1,2-tetrafluoroethane, preferably 1,1,1,2-tetrafluoroethane and chlorine are used to reduce the amount of dichlorotetrafluoroethane produced. It is preferred to carry out the chlorination using a molar ratio of about 10: 1 to about 1: 1, more preferably about 6: 1 to about 1: 1, especially about 5: 1 to about 2: 1.
[0021]
The chlorination step (i) and the hydrofluorination step (iii) can be carried out in the same reactor, in which case this process is chlorofluorination and the product from the reactor is for example Processed by distillation, formula C₂HCl_xF_yUnreacted compound of formula C₂H₂X_FourA pentafluoroethane stream and a formula C to recover one or more recycle streams comprising₂Cl_{x + 1}F_yFrom a waste stream containing
[0022]
Appropriate temperature and pressure conditions for chlorofluorination of 1,1,1,2-tetrafluoroethane are well known to those skilled in the art and are described, for example, in U.S. Pat. It is preferable to use 1,1,2-tetrafluoroethane in the ratio as described above rather than the ratio described in the above US patent specification.
[0023]
Alternatively, in a preferred embodiment (A) of the present invention, step (i) and step (iii) can be carried out in separate reactors, and the chlorination reactor of step (i) and step (iii) These hydrofluoric treatment reactors are preferably arranged in series or in parallel.
[0024]
In the reactor system arranged in series, tetrafluoroethane is chlorinated in the gas phase in the reactor of step (i) and the product stream is fed to a separator where hydrogen chloride is fed, for example, with an aqueous scrubber. Used or removed by distillation, unconverted tetrafluoroethane is separated, for example, by distillation and then fed to a chlorination reactor, leaving a product stream consisting of chlorotetrafluoroethane and dichlorotetrafluoroethane. A chlorotetrafluoroethane / dichlorotetrafluoroethane mixture is fed to a distillation apparatus where chlorotetrafluoroethane is separated from dichlorotetrafluoroethane and the chlorotetrafluoroethane is then fluorinated in step (iii) containing a fluorination catalyst. Feed to hydrotreating reactor.
[0025]
In a reactor system arranged in parallel, the chlorination reactor and the hydrofluorination reactor are arranged in parallel so that the product streams from each reactor are combined and / or a common purification device, for example Can be supplied to a series of distillation equipment, which separates pentafluoroethane, tetrafluoroethane, chlorotetrafluoroethane and dichlorotetrafluoroethane, and feeds chlorotetrafluoroethane to the hydrofluorination reactor And tetrafluoroethane is recycled to the chlorination reactor. In this parallel operation, the product stream from the hydrofluorination reactor is first treated, for example, by phase separation and distillation, before being combined with the product stream from the chlorination reactor, to a large extent. Is preferably removed and recycled.
[0026]
In a second preferred embodiment (B) of the invention wherein step (i) comprises contacting perhaloethylene or pentahaloethane with hydrogen fluoride in the liquid phase or in the gas phase and in the presence of a fluorination catalyst. In this case, the starting material is preferably perhaloethylene, and the method of step (i) is preferably carried out in the gas phase at a high temperature.
[0027]
The temperature at which step (i) is carried out can be from about 150 ° C to about 400 ° C, preferably from about 180 ° C to about 380 ° C, in particular from about 200 ° C to about 370 ° C. Atmospheric pressure or superatmospheric pressure may be used, but pressures above atmospheric pressure, for example pressures up to 30 barg, in particular from about 5 barg to about 20 barg are used. It is preferable.
[0028]
The relative ratio of hydrogen fluoride to perchlorethylene can be varied within a very wide range, but it is preferred to use a stoichiometric excess of hydrogen fluoride. The molar ratio of hydrogen fluoride to perchlorethylene is usually greater than about 3: 1 and preferably greater than 5: 1. Use a molar ratio of hydrogen fluoride to perchlorethylene in the range of about 5: 1 to about 20: 1, preferably about 7: 1 to about 15: 1, especially about 7: 1 to about 12: 1. Is preferred.
[0029]
The catalyst used in the preferred embodiment (B) of the process of the invention is any known fluorination catalyst, in particular a fluorination catalyst having a high activity for the conversion of perchloroethylene to hydrochlorofluoroethane, such as chromia, It may be a catalyst based on chromium oxyfluoride, alumina or aluminum fluoride and which may also contain one or more metals such as nickel, cobalt, iron, zinc and the like. It is preferred to use chromia or zinc-supported chromia catalysts, since these catalysts have a particularly high per pass conversion of perchloroethylene to hydrochlorofluoroethane.
[0030]
In this preferred embodiment (B) of the present invention in which step (i) comprises a hydrofluoric treatment, both step (i) and step (iii) are hydrofluoric treatment processes, and step (i) and step (i) The catalyst used in iii) can be the same or different, so if desired, the two steps (i) and (iii) can be carried out from the fluorination catalyst in a single reactor. On a single catalyst bed, whereby pentafluoroethane can be produced. In this case, the product stream from a single reactor is fed to a refiner system, for example a series of distillation columns, where the formula C₂HCl_xF_yOne or more recycle streams consisting of the above compounds and unreacted starting material, eg perchlorethylene, are recovered with a pentafluoroethane stream and a formula C₂Cl_{x + 1}F_yFrom the waste stream containing the compound. In this embodiment using a single reactor, the catalyst can be a catalyst as described for step (i) or step (iii), if desired.
[0031]
However, in this preferred embodiment (B) of the process of the invention it may be preferred in some cases to use a different catalyst for step (i) or step (iii) of the process of the invention. Admitted. For example, for the conversion of perchlorethylene in step (i) of the method of the present invention, it is preferable to use a catalyst having a high activity (single-flow conversion), while from hydrochlorofluoroethane in step (iii). For the production of pentafluoroethane, it is preferable to use a catalyst having a high selectivity.
[0032]
The catalysts used in step (i) and step (iii) of the process of the present invention can be in different reaction zones of the same reactor or each catalyst can be in a separate reactor.
[0033]
If the catalyst for step (i) and the catalyst for step (iii) are present in separate reactors, the two reactors can be arranged in parallel or in series.
[0034]
In the embodiment in which the two reactors of step (i) and step (iii) are arranged in series, the product stream from one reactor of step (i) or step (iii) is transferred to the other reactor. The product stream from this other reactor can be fed to the purification system where step (ii) is carried out. For example, the product stream from the reactor of step (i) is passed to the reactor of step (iii) and the product stream from the reactor of step (iii) is fed to the purification system where step (ii) is performed. You can. Alternatively, the product stream from the reactor of step (i) is passed to the purifier system where step (ii) is carried out and unreacted starting material, with formula C₂Cl_{x + 1}F_yThe compound of formula C was isolated₂HCl_xF_yOne or more of the effluents from the purifier comprising the above compounds may be passed to the reactor of step (iii). The product stream from the reactor of step (iii) can be passed to the reactor of step (i).
[0035]
However, it is preferred to substantially remove hydrogen chloride prior to performing step (iii) of the method of the present invention. Hydrogen chloride is produced as a substantial by-product from step (i) of the process of the present invention, thus supplying the product stream from the reactor of step (i) to the purifier system where step (ii) is conducted. The product stream from the reactor of step (iii) is preferably sent to the reactor of step (i).
[0036]
According to another preferred embodiment of the present invention, (i) perchlorethylene is contacted with hydrogen fluoride in the presence of a fluorination catalyst to give a compound of formula C₂Cl_{x + 1}F_yOf formula C₂HCl_xF_y(Ii) wherein x = 1,2 or 3 and y = 2,3 or 4 provided that x + y is 5. Formula C₂HCl_xF_yA compound of formula C₂Cl_{x + 1}F_y(Iii) Formula C₂HCl_xF_yContacting said compound with hydrogen fluoride in the presence of a fluorination catalyst thereby producing pentafluoroethane and recycling the product stream from step (iii) to the reactor of step (i). A featured method for producing pentafluoroethane is provided.
[0037]
In an embodiment in which the reactors of step (i) and step (iii) are arranged in parallel, the product stream from the two reactors is supplied to a common purification unit system in which step (ii) is performed, and this purification unit Pentafluoroethane is recovered from the reactor, unconverted perhaloethylene is recycled to the reactor of step (i), and unconverted Formula C₂HCl_xF_yIt is preferred to recycle the compound of step (iii) to the reactor.
[0038]
In step (ii), the product stream fed from the reactor in the embodiment using a single reactor or from one of the two reactors in the embodiment using two reactors to the purifier system. Is typically the formula C₂HCl_xF_yCompounds of the formula, in particular dichlorotrifluoroethane and chlorotetrafluoroethane, of formula C₂Cl_{x + 1}F_yCompounds, especially trifluorotrifluoroethane and dichlorotetrafluoroethane, pentafluoroethane, chloropentafluoroethane, unreacted hydrogen fluoride and perchloroethylene, by-product hydrogen chloride and small amounts of other by-products such as 1, It consists of 1,1-trifluoro-2-chloroethane and 1,1,1,2-tetrafluoroethane.
[0039]
This product stream is supplied, for example, to a purification system consisting of a first distillation column, from which hydrogen fluoride, dichlorotrifluoroethane [HCFC 123 / 123a] and other heavy products are used as the bottom fraction. The remainder of the product stream is removed as the top fraction. The bottom fraction from this first distillation column can be recycled to the single reactor or one or both of the two reactors.
[0040]
The top fraction from the first distillation column is optionally scrubbed and then dried to remove acidic components, hydrogen chloride and hydrogen fluoride, and then fed to the second distillation column from the second distillation column. Pentafluoroethane [HFA 125] is withdrawn as a top fraction together with chloropentafluoroethane [CFC 115], mainly chlorotetrafluoroethane [HCFC 124 / 124a], chlorotrifluoroethane [HCFC 133 / 133a], tetrafluoroethane [HFA 134 / 134A] and dichlorotetrafluoroethane [CFC 114 / 114a] are taken off as the bottom fraction. The pentafluoroethane containing chloropentafluoroethane, taken as the top fraction, can be further processed to effect purification of the pentafluoroethane.
[0041]
The bottom fraction from the second distillation column is fed to the third distillation column, tetrafluoroethane [HFA 134 / 134A] is withdrawn from the third distillation column as the top fraction, and the remainder of the product stream is withdrawn as the bottom fraction. Chlorotetrafluoroethane [HCFC 124 / 124a] is withdrawn as a top fraction from this fourth distillation column, while dichlorotetrafluoroethane [CFC 114 / 114a] and chlorotrifluoroethane [HCFC 133 / 133a] ] As a bottom fraction. Chlorotetrafluoroethane [HCFC 124 / 124a] can be recycled to the reactor for fluorination to pentafluoroethane [HFA 125]. The bottom fraction from the fourth distillation column can usually be treated, for example, by thermal oxidation.
[0042]
The refiner system used in the preferred embodiment (B) of the present invention comprises unreacted perchloroethylene and unconverted Formula C.₂HCl_xF_yA first distillation column for separating the compound from the other components (as the top stream) from the bottom stream and recycling to the reactor of step (i), and pentafluoroethane from the other components of the top stream It consists of at least one additional (another) distillation column for separating and recovering, separating and recycling chloropentafluoroethane from dichlorotetrafluoroethane.
[0043]
The top stream from the first distillation column is preferably treated to remove at least hydrogen chloride. In particular, the top stream from the first distillation column can be scrubbed with water to remove hydrogen fluoride and hydrogen chloride before feeding it to at least one additional distillation column. However, in this case, the hydrogen fluoride in the top stream is also removed, resulting in a decrease in the efficiency of hydrogen fluoride in the process of the present invention. Alternatively, the top stream from the first distillation column itself can be distilled to separate the top stream consisting of hydrogen chloride, pentafluoroethane and chloropentafluoroethane from the bottom stream consisting of other components. This bottom stream can then be fed to at least one other distillation column, while the top stream can be fed to the distillation column to separate pentafluoroethane from the top stream.
[0044]
When aqueous scrubbing is used to remove hydrogen chloride and hydrogen fluoride, it is preferred that at least one additional distillation column comprises two distillation columns; pentafluoroethane in the first additional distillation column. Is separated from chlorotetrafluoroethane and dichlorotetrafluoroethane, and in a second additional distillation column, dichlorotetrafluoroethane is separated from chlorotetrafluoroethane. When distillation is used to remove hydrogen chloride from the top stream from the first distillation column, at least one additional distillation column is one for separating chlorotetrafluoroethane from dichlorotetrafluoroethane. Only a distillation column is required. If this optional method (ie, distillation to remove hydrogen chloride) is used, the distillation to separate 114 / 114a from 124 / 124a is performed in the presence of hydrogen fluoride, and the separation The top stream from the distillation column carrying out is composed of chlorotetrafluoroethane, dichlorotetrafluoroethane and hydrogen fluoride and treated with hydrofluorination to pentafluoroethane, i.e. fluorination as in step (iii) of the process of the invention. A novel composition particularly suitable for hydroprocessing.
[0045]
According to a second aspect of the invention, (i) at least 50% to about 95% by weight of chlorotetrafluoroethane, (ii) about 0.5% to about 20% by weight of hydrogen fluoride and (iii) 2 Compositions suitable for conversion to pentafluoroethane are provided, consisting of up to% by weight of dichlorotetrafluoroethane (wherein% by weight is based on the total weight of these three components present in the composition). .
[0046]
The above composition may contain other ingredients such as other formula C₂HCl_xF_yAnd other formulas C₂Cl_{x + 1}F_yMay be further included in small amounts, usually up to 10% by weight of the composition, typically up to 5% by weight of the composition. Thus, the above weight percentages for the components of the composition are usually also weight percentages based on the total weight of the composition. Preferably, the amount of dichlorotetrafluoroethane in the composition will be 1% by weight or less, in particular 0.5% by weight or less. The composition preferably also contains from about 1% to about 10% by weight of hydrogen fluoride and will usually contain at least 75% by weight of chlorotetrafluoroethane.
[0047]
Step (iii) of the method of the invention can be carried out in the liquid phase or in the gas phase, but in particular in the gas phase when step (i) is a gas phase hydrofluorination of perhaloethylene or pentahaloethane. Preferably it is done. Gas phase reactions of dichlorotrifluoroethane and chlorotetrafluoroethane with hydrogen fluoride are well known to those skilled in the art, and appropriate temperature and pressure conditions, appropriate fluorination catalysts and relative proportions of reactants are well documented in the literature. Has been.
[0048]
Suitable fluorination catalysts include those based on chromia and chromium oxyfluoride or alumina and aluminum fluoride. Other metals that promote activity may also be present, such as zinc, nickel and iron. Preference is given to using the catalysts described in EP 502605 or WO 93/16798, in particular the catalysts described in EP 502605 in which an activity promoting amount of zinc is supported on chromia or chromium oxyfluoride.
[0049]
The temperature of step (iii) of the process of the present invention can be from about 200 ° C to about 500 ° C, preferably from about 250 ° C to about 350 ° C. This step is conveniently performed near atmospheric pressure, but pressures below atmospheric pressure or pressures above atmospheric pressure, for example pressures up to about 20 bar, can be used if desired. In fact, pressures above atmospheric pressure up to about 2 to about 15 bar are used to promote gas throughput and reduce the required reactor size [two reactions In the preferred embodiment (B) of the present invention using a reactor, it is preferable to operate the two reactors at substantially the same pressure, and the slight pressure difference that occurs between the reactors Naturally as a result of gas flow].
[0050]
The molar ratio of hydrogen fluoride to chlorotetrafluoroethane can be from about 1 to about 10; it is preferred to use an excess of moles of hydrogen fluoride.
[0051]
The present invention will be described below with reference to the drawings.
In the apparatus system shown in FIG. 1, a gaseous chlorine feed stream 101 and a gaseous 1,1,1,2-tetrafluoroethane feed stream 102 are fed to a chlorination reactor 103. Product gas stream 124 from the chlorination reactor is fed to aqueous scrubber unit 104 where hydrogen chloride and unreacted chlorine are separated from organic stream 125 as aqueous stream 105. Organic stream 125 is dried and compressed in compressor 106 and fed to distillation column 107 where 1,1,1,2-tetrafluoroethane (HFA 134a) is converted to chlorotetrafluoroethane (HCFC 124) and dichloromethane. Separate from tetrafluoroethane (CFC 114a). The HFA 134a stream 108 is recycled to the chlorination reactor 103. HCFC 124 / CFC 114a stream is fed to distillation column 109, where HCFC 124 stream 110 is separated from CFC 114a stream 111. The HCFC 124 product stream 110 from the distillation column is fed to a hydrofluoric treatment reactor 113 containing a gaseous hydrogen fluoride 112 and a chromia catalyst. Product gas stream 126 from this reactor is fed to distillation column 114, where fluid 115 consisting of unreacted hydrogen fluoride and HCFC 124 are separated from other components of the product stream and recycled to reactor 113. Let The remainder 127 of the product stream from the distillation tower is fed to an aqueous scrubber unit 116 where hydrogen chloride and the remainder of hydrogen fluoride are separated from the organic stream 128 as an aqueous stream 117. Organic stream 128 is fed to compressor 118 and then to distillation column 119, where pentafluoroethane product stream 120 is separated from organic stream 129 composed of other organic components. Organic stream 129 is fed to second distillation column 121 where HCFC 124 stream 122 is separated from heavy byproduct stream 123. HCFC 124 stream 122 is recycled to reactor 113.
[0052]
In the embodiment shown in FIG. 2, a gaseous chlorine feed stream 201 and a gaseous 1,1,1,2-tetrafluoroethane feed stream 202 are fed to a chlorination reactor 203 comprising an Inconel tube.
[0053]
Hydrogen fluoride stream 204 and HCFC 124 recycle stream 216 (discussed below) from distillation column 215 are fed to hydrofluorination reactor 205 containing a chromia catalyst, and product gas stream 220 is fed to distillation column 206. Where the fluid 207 comprising unreacted hydrogen fluoride and HCFC 124 are separated from the fluid 221 comprising the remainder of the product stream and the fluid 207 is recycled to the reactor 205. Fluid 221 from distillation tower 206 is combined with product stream 219 from chlorination reactor 203 and fed to aqueous scrubber device 208 where the remainder of hydrogen chloride, chlorine and hydrogen fluoride is organic stream 222 as aqueous stream 209. Separate from. The organic stream 222 from the scrubber device 208 is dried, compressed in the compressor 210 and fed to the distillation column 211 to separate the pentafluoroethane stream 212 from the organic stream 223 consisting of HFA 134a, HCFC 124 and CFC 114a. Organic stream 223 is fed to distillation column 213 where HFA 134a stream 214 is separated from organic stream 224 consisting of HCFC 124 and CFC 114a. The HFA 134a stream 214 is recycled to the reactor 203. Organic stream 224 is fed to distillation column 215 where HCFC 124 stream 216 is separated from CFC 114a stream 217 and HCFC 124 stream 216 is recycled to reactor 205.
[0054]
In the embodiment shown in FIG. 3, a gaseous feed stream 318 comprising a feed hydrogen fluoride stream 301, a feed perchlorethylene stream 302, a recycle hydrogen fluoride and organic stream 307 (described below), and an HCFC 124 recycle stream 316. Is fed to a hydrofluoric treatment reactor 303 containing a chromia catalyst. Product gas stream 304 is fed to distillation column 305, which contains unreacted hydrogen fluoride, perchlorethylene and incomplete (or partially) underfluorinated organic intermediates such as HCFC 121, 122 and 123. Fluid 307 is separated from products HFA 125, HCFC 124, CFC 114 / 114a and fluid 306 consisting of hydrogen chloride and HF. Fluid 306 is fed to an aqueous scrubber device 309 where hydrogen chloride and residual HF are separated from the organic stream 310 as an aqueous stream 308. Organic stream 310 is dried, compressed in compressor 311 and fed to distillation column 312 to separate HFA 125 stream 313 from fluid 314 containing HCFC 124 and CFC 114 / 114a. Fluid 314 is fed to distillation column 325 where HCFC 124 stream 316 is separated from fluid 317 enriched in CFC 114 / 114a.
[0055]
In the embodiment shown in FIG. 4, a gaseous form comprising raw hydrogen fluoride 401, raw perchlorethylene stream 402 and incompletely fluorinated intermediate 407 to recycled hydrogen fluoride / perchloroethylene / HFA 125. Fluid 403 is fed to a hydrofluoric treatment reactor 404 containing a chromia catalyst. Product gas stream 405 is mixed with fluid 413 containing product gas from parallel hydrofluoric reactor 412 and fed to distillation column 406 where HF and perchlorethylene (and some incomplete fluorine). Fluid 407 containing HCFCs 121, 122, etc.) is removed from the bottom of the distillation column and recycled to the reactor 404. Fluid 408 containing HF and (primarily) HCFC 123 is withdrawn from the side of distillation column 406 as a side stream and mixed with fluid 422 containing recirculated HCFC 124 and optionally fluid 410 providing feed HF; The combined stream 411 is supplied as a gas to a hydrogen fluoride treatment reactor 412 containing a chromia catalyst. The product gas from this reactor, ie, fluid 413 is fed to distillation column 406 as described above. Product HFA 125, HCFC 124, CFC 114 and 114a, light fluid 409 containing hydrogen chloride and some HF is removed from the top of distillation column 406 and fed to aqueous scrubber unit 414 where HF and hydrogen chloride are aqueous Separate from organic stream 416 as 415. Organic stream 416 is dried, compressed in compressor 417 and fed to distillation column 418, where HFA 125 stream 419 is separated from fluid 420 containing HCFC 124 and CFC 114 / 114a. Fluid 420 is fed to distillation column 421 where HCFC 124 stream 422 is separated from fluid 423 enriched in CFC 114 / 114a.
[0056]
In the embodiment shown in FIG. 5, feed hydrogen fluoride stream 501, feed perchlorethylene stream 502, incomplete fluorinated intermediate recycle stream 506 to hydrogen fluoride / perchloroethylene / HFA 125 and hydrogen fluoride treatment. A gaseous fluid 522 consisting of product gas from the reactor 510 is supplied to a hydrofluoric treatment reactor 503 containing a chromia catalyst. Product gas 504 is fed to distillation column 505, where fluid 506 containing HF and perchlorethylene (and some incompletely fluorinated HCFC 121, 122, etc.) is removed from the bottom of the distillation column and recycled to reactor 503. Circulate. Fluid 507 containing HF and (mainly) HCFC 123 is withdrawn as a side stream and mixed with fluid 520 containing recirculated HCFC 124 and, optionally, fluid 508 providing feed HF; The hydrogen fluoride treatment reactor 510 containing the chromia catalyst is supplied. A light organic substance-product HFA 125, HCFC 124, CFC 114, 114a, etc., a fluid 511 containing hydrogen chloride and HF is removed from the top of distillation column 505. Hydrogen chloride and HF in this fluid are separated by aqueous scrubber unit 512 as aqueous acidic stream 513, while organic stream 514 is dried, compressed in compressor 515 and fed to distillation column 516, where HFA 125 stream 517 is separated from fluid body 518 containing HCFC 124 / CFC 114 / 114a. Fluid 518 is fed to distillation column 519 where HCFC 124 recycle stream 520 is separated from bottom fluid 521 enriched in CFC 114 / 114a.
[0057]
In the embodiment shown in FIG. 6, a gas stream 603 comprising raw material HF601, raw material perchlorethylene 602 and incomplete fluorinated intermediate recycle stream 609 to HF / perchlorethylene / HFA 125 is accommodated in a chromia catalyst. The hydrogen fluoride treatment reactor 604 is supplied. Product gas 605 is mixed with a combined fluid of recycle stream 610 containing HF and (mainly) HCFC 123 and HCFC 124 recycle stream 620 to form gas stream 605. This gas stream 605 is fed to another hydrofluorination reactor 606 that also contains a chromia catalyst. Product gas 607 is fed to distillation column 608, where fluid 609 containing HF and perchlorethylene (and some incompletely fluorinated HCFC 121, 122) is withdrawn from the bottom of the column and recycled to reactor 604. Fluid 610 consisting of HF and primarily HCFC 123 is withdrawn as a side stream, combined with recycle stream 620 and then returned to reactor 606; and products HFA 125, HCFC 124, CFC 114, 114a, hydrogen chloride and A light fluid 611 containing some HF is fed to the aqueous scrubber unit 612. In apparatus 612, hydrogen chloride and HF are separated from organic stream 614 as aqueous stream 613. Organic stream 614 is dried and compressed in compressor 615 and fed to distillation column 616 where HFA 125 stream 617 is separated from fluid body 618 containing HCFC 124 / and CFC 114 / 114a. Fluid 618 is fed to distillation column 619 where HCFC 124 recycle stream 620 is separated from bottom fluid 621 enriched in CFC 114 / 114a.
[0058]
In the embodiment shown in FIG. 7, a gaseous feed stream 714 comprising a feed hydrogen fluoride stream 701, a perchlorethylene stream 702, a recycle HF / organic stream 707 and a hydrogen fluoride / tetrafluorochloroethane recycle stream 712 is chromia. The hydrogen fluoride treatment reactor 703 containing the catalyst is supplied. Product gas stream 704 is fed to distillation column 705, where fluid 707 containing unreacted hydrogen fluoride, perchlorethylene and incompletely fluorinated organic intermediates such as HCFC 121, 122, 123 and 1111 is produced as product. Separate from fluid 706 containing HFA 125, HCFC 124, CFC 114 / 114a, hydrogen chloride and hydrogen fluoride. Fluid 706 is fed to distillation column 708, where fluid 709 containing hydrogen chloride, product HFA 125 and a small amount of HF is withdrawn as overhead effluent and final product treatment [eg, aqueous scrubbing, drying, compression and distillation] Meanwhile, tetrafluorochloroethane, HF, CFC 114a, CFC 114 and HCFC 133 are withdrawn as bottom effluent 710. A bottom effluent 710 is fed to a distillation column 711 where a fluid 712 containing HF and tetrafluorochloroethane is withdrawn as a top effluent and recirculated to the reactor 703 while a C713 114 / 114a rich fluid 713 is obtained. Take out from the bottom of the tower.
[0059]
【Example】
Example 1  Treatment of chlorotetrafluoroethane with hydrogen fluoride
By charging 2 g of chromia catalyst with a particle diameter of 1 mm into an Inconel tube reactor with an inner diameter of 1/4 inch, hydrogen fluoride is passed over the catalyst at 300 ° C. for 24 hours at a flow rate of 20 ml / min. Prefluorinated. Subsequently, chlorotetrafluoroethane at a flow rate of 8 ml / min was added to the raw hydrogen fluoride, and the mixture was passed over the catalyst. Samples of reactor offgas were taken at various temperatures and analyzed by gas chromatography. The results are shown in Table 1.
[0060]

[0061]
No chloropentafluoroethane is observed in the product gas, so this example illustrates that the production of chloropentafluoroethane is eliminated when CFC 114 / 114a is not present in the HCFC 124 starting material. is doing.
[0062]
Example 2
Chromia catalyst (1 g) was charged into an Inconel reactor (1/4 inch diameter). HF (60 ml / min) was passed over the catalyst at 340 ° C. for 16 hours. Chlorine flow and HCFC 133a flow were introduced at the following flow rates. The offgas composition from the reactor was monitored by gas chromatography. The results are shown in Table 2.
[0063]

[0064]
Example 3  Purification of HCFC 124 from a mixture containing 124, 114 and 114a
This example illustrates the ease of separation of CFC 114 / 114a from HCFC 124 by distillation compared to separating CFC 115 from HFA 125.
In this example, all compositions are given in mole percent.
90 mol% in a reactor consisting of a 250 ml flask, 5 theoretical stage vacuum jacketed packed column, packed with Raschig ring, condenser and take-off controller 150 g of a mixture of 124, 4.5 mol% 114 / 114a and 5.5 mol% 133a were introduced. The packed tower was stabilized to about -12 C under total reflux at atmospheric pressure. After equilibration, a vapor sample was taken from the top; gas chromatographic analysis showed that the sample had the following composition:
124-99.4
133a-0.15
114 / 114a-0.08
[0065]
Distillation was continued at a reflux ratio of 5: 1 until about half of the original feed mixture was distilled. A sample of the vapor was taken from the top of the distillation column; the results of the gas chromatographic analysis showed that this sample had the following composition:
HCFC 124-99.88
CFC 114 / 114a-not detected
HCFC 133a-not detected
[0066]
Comparative Example 1
Example 3 was repeated using the same equipment as used in Example 3 and using a mixture of HFA 125-98.2% and CFC 115-1.8%. After equilibration to about -50C under total reflux, a vapor sample was taken; the vapor sample had the following composition:
HFA 125-98.0
CFC 115-2.0
After continuing distillation at a reflux ratio of 5: 1 until about half of the raw material mixture was distilled, the distillate had the following composition:
HFA 125-98.3
CFC 115-1.7
[Brief description of the drawings]
FIG. 1 is an embodiment of the invention using two reactors, wherein step (i) is chlorination of 1,1,1,2-tetrafluoroethane and the two reactors are arranged in series It is a schematic flow diagram when
FIG. 2 is an embodiment of the invention using two reactors, wherein step (i) is chlorination of 1,1,1,2-tetrafluoroethane and the two reactors are arranged in parallel It is a schematic flow diagram when
FIG. 3. Step (i) is hydrofluorination of perchlorethylene, steps (i) and (iii) are performed in a single reactor and hydrogen chloride is removed using aqueous scrubbing. 1 is a schematic flow diagram showing an embodiment of the present invention.
FIG. 4 is an embodiment of the present invention using two reactors, wherein step (i) is a hydrofluorination of perchloroethylene, and the two reactors are arranged in parallel. Is a schematic flow diagram showing
FIG. 5 is an embodiment of the present invention using two reactors, wherein step (i) is a hydrofluorination of perchloroethylene and the two reactors are arranged in series. Is a schematic flow diagram of
FIG. 6 is an embodiment of the present invention using two reactors, wherein step (i) is a hydrofluorination of perchloroethylene and the two reactors are arranged in series. Is a schematic flow diagram of
FIG. 7 is a schematic flow diagram showing an embodiment of the present invention when step (i) is hydrofluorination of perchlorethylene and steps (i) and (iii) are carried out in a single reactor. is there.

Claims (8)

(i) In the first reactor, perchlorethylene is reacted with hydrogen fluoride in the gas phase at high temperature in the presence of a fluorination catalyst to mix the compound of formula C ₂ Cl _{x + 1} F _y Containing a compound of formula C ₂ HCl _x F _y where x = 1, 2 or 3 and y = 2, 3 or 4, provided that x + y is 5 Producing a composition;
(ii) subjecting the composition from step (i) to a separation step of separating the compound of formula C ₂ HCl _x F _{y from} the compound of formula C ₂ Cl _{x + 1} F _y , and dichlorotrifluoroethane; and hydrogen fluoride, wherein C ₂ containing a compound of Cl _{x + 1} F _y, wherein C ₂ Cl _{x + 1} F wherein C ₂ content of the compound of _y is present in the composition HCl _x F _y And the compound C ₂ Cl _{x + 1} F _y Obtaining a composition of 1% by weight or less based on the total weight of the compounds of
(iii) In the second reactor, the dichlorotrifluoroethane produced in step (ii) is reacted with hydrogen fluoride at high temperature in the gas phase in the presence of a fluorination catalyst to form chloro Ri Do the step of producing pentafluoroethane composition containing 1% by weight of chloropentafluoroethane, based on the total weight of pentafluoroethane and pentafluoroethane, step (i), (ii) and (iii) Are performed in this order as a continuous process. Step process the product stream from (iii) unconverted formula C ₂ HCl _x F the compound of _y is separated from the pentafluoroethane then a compound of formula C ₂ HCl _x F _y unconverted step (i) or The method of claim 1, further comprising the step of recycling to step (iii). The process according to claim 1 or 2 , wherein step (ii) comprises distilling the composition. Step (i) compositions prepared by, based on the total weight of the formula C ₂ HCl _x compound of F _y and compounds of formula C ₂ Cl _{x + 1} F _y present in the composition, 0.1 % 2 0 containing the weight percent of the compound of formula _{C 2 Cl x + 1 F y} , the method according to any one of claims 1-3. Step (iii) is carried out at a temperature of 200 ℃ ~ 5 00 ℃, method according to any one of claims 1-4. The method according to any one of claims 1 to 5, wherein in step (i) and / or step (iii), the fluorination catalyst is chromia, chromium oxyfluoride, alumina or aluminum oxyfluoride. The process according to claim 6 , wherein in step (iii), the fluorination catalyst comprises one or more metals and chromia, chromium oxyfluoride, alumina or aluminum oxyfluoride. 8. The method of claim 7 , wherein in step (iii), the fluorination catalyst comprises an amount of zinc that promotes activity and chromia, chromium oxyfluoride, alumina, or aluminum oxyfluoride.

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