METHOD FOR PRODUCING FLUORINATED COMPOUNDS
5 FIELD OF THE INVENTION
The present invention relates to a process for producing fluoro
compounds, such as hydrofluoroolefins or fluorohydrocarbons, for
example, and to an installation adapted to the implementation of this
process.
10
TECHNICAL BACKGROUND
It is known practice to produce hydrofluoroolefins or
fluorohydrocarbons by fluorination of hydrochloroolefins or
chlorohydrocarbons, especially. This fluorination is generally a catalytic
15 fluorination using hydrofluoric acid as fluorinating agent.
The fluorination reaction must generally be performed- at a high
temperature (above 300°C) in the gas phase. Consequently, it is known
practice to heat, vaporize and superheat the reagents before the
fluorination reaction, using heat exchangers.
20 However, this preliminary step of heating, vaporization and
superheating of the reagents has a tendency to lead to the production of
coke in the heat exchangers.
There is thus a need to develop a process for producing fluoro
compounds that limits or avoids the problem of coking of the installation.
25
SUIMMARY OF THE INVENTION
The &ention relates firstly to a process for producing a fluoro
compound, involving:
- supplying a gas stream comprising hydrofluoric acid;
30 - supplying at least one liquid stream of chloro compound and
vaporizing said compound by mixing with said gas stream, the
resulting mixture being a gaseous mixture;
- catalytically reacting the chloro compound with the hydrofluoric
acid in the gas phase and collecting a product stream.
35 According to one embodiment:
- the chloro compound is a chlorocarbon, a chlorohydrocarbon, a
chlorofluorocarbon, a hydrochlorofluorocarbon, a chloroolefin, a
hydrochloroolefin, a chlorofluoroolefin or a
hydrochlorofluoroolefin; and the fluoro compound is a
fluorocarbon, a fluorohydrocarbon, a chlorofluorocarbon, a
hydrochlorofluorocarbon, a fluoroolefin, a hydrofluoroolefin, a
chlorofluoroolefin or a hydrochlorofluoroolefin; and
- preferably, the chloro compound is chosen from 1,1,2-
trichloroethane, 1 ,I ,I ,2,3-pentachloropropane, I ,I ,I ,3,3-
pentachloropropane, 1,1,2,2,3-pentachloropropane, 2,3-
dichloro-I ,II,-t rifluoropropane, perchloroethylene, 1,2-
dichloroethylene, 1 ,I ,2,3-tetrachloropropene, 2,3,3,3-
tetrachloropropene, 1,1,3,3-tetrachloropropene, 1,3,3,3-
tetrachloropropene, 2-chloro-3,3,3-trifluoropropene and l-chloro-
15 3,3,3-trifluoropropene, and mixtures thereof;
-- preferably, the fluoro compound is chosen from
pentafluoroethane, I-chloro-2,2-difluoroethane, 1,3,3,3-
tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 2-chloro-3,3,3-
trifluoropropene and 1-chloro-3,3,3-trifluoropropene, and
20 mixtures thereof;
- more particularly preferably, the chloro compound is
perchloroethylene and the fluoro compound is
pentafluoroethane, or the chloro compound is 1,1,1,2,3-
pentachloropropane and the fluoro compound is 2,3,3,3-
25 tetrafluoropropene.
According to another embodiment, the chloro compound is 1,1,3,3-
tetrachloropropene and the fluoro compound is 1-chloro-3,3,3-
trifluoropropene; or the chloro compound is 1-chloro-3,3,3-trifluoropropene
and the fluoro compound is 1,3,3,3-tetrafluoropropene; or the chloro
30 compound is 1 ,I ,2-trichloroethane and the fluoro compound is l-chloro-
2,2-difluoroethane.
According to one embodiment, the mixing of the liquid stream of
chloro compound with the gas stream comprising hydrofluoric acid is
performed in a static mixer.
35 According to one embodiment, the process comprises one or more
steps of separating the product stream, making it possible to collect, on the
one hand, a stream of fluoro compound and, on the other hand, a recycling
stream.
According to one embodiment, the recycling stream provides the gas
stream comprising hydrofluoric acid, optionally after supplying hydrofluoric
5 acid.
According to one embodiment, the process comprises a step of
catalytic fluorination of the recycling stream, where appropriate with a
supply of hydrofluoric acid, the gas stream comprising hydrofluoric acid
being collected on conclusion of this fluorination step.
10 According to one embodiment, the process comprises a step of
heating the liquid stream of chloro compound to a temperature below its
vaporization temperature.
According to one embodiment, the process comprises, after the step
of mixing the liquid stream of chloro compound with the gas stream
15 comprising hydrofluoric acid, and before the step of catalytic reaction of the
- chloro compound with the hydrofluoric acid: -
- a step of heating the mixture; or
- a step of cooling the mixture.
The invention also relates to an installation for producing a fluoro
20 compound, comprising:
- a pipe for supplying a liquid stream of chloro compound;
- a pipe for supplying a gas stream comprising hydrofluoric acid;
- a mixing and vaporizing unit fed by the pipe for supplying the
liquid stream of chloro compound and the pipe for supplying the
gas stream comprising hydrofluoric acid;
- a pipe for collecting a gas mixture at the outlet of the mixing and
vaporizing unit;
- a catalytic fluorination reactor fed by the pipe for collecting the
gas mixture; and
30 - a pipe for collecting the product stream at the outlet of the
catalytic fluorination reactor.
According to one embodiment:
- the chloro compound is a chlorocarbon, a chlorohydrocarbon, a
chlorofluorocarbon, a hydrochlorofluorocarbon, a chloroolefin, a
hydrochloroolefin or a hydrochlorofluoroolefin; and the fluoro
compound is a fluorocarbon, a fluorohydrocarbon, a
chlorofluorocarbon, a hydrochlorofluorocarbon, a fluoroolefin, a
hydrofluoroolefin or a hydrochlorofluoroolefin; and
- preferably, the chloro compound is chosen from 1,1,2-
trichloroethane, 1 ,I ,I ,2,3-pentachloropropane, 1,1,1,3,3-
pentachloropropane, 1 ,I ,2,2,3-pentachloropropane, 2,3-
dichloro-I ,I ,I- trifluoropropane, perchloroethylene, 1,2-
dichloroethylene, 1,1,2,3-tetrachloropropene, 2,3,3,3-
tetrachloropropene, 1, I,3 ,3-tetrachloropropene, 1,3,3,3-
tetrachloropropene, 2-chloro-3,3,3-trifluoropropene and l-chloro-
10 3,3,3-trifluoropropene, and mixtures thereof;
- preferably, the fluoro compound is chosen from
pentafluoroethane, 1 -chloro-2,2-difluoroethane, 1,3,3,3-
tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 2-chloro-3,3,3-
trifluoropropene and I-chloro-3,3,3-trifluoropropene, and
mixtures thereof;
- more particularly preferably, the chloro compound is
perchloroethylene and the fluoro compound is
pentafluoroethane, or the chloro compound is I ,I ,I ,2,3-
pentachloropropane and the fluoro compound is 2,3,3,3-
20 tetrafluoropropene.
According to another embodiment, the chloro compound is 1 ,I ,3,3-
tetrachloropropene and the fluoro compound is 1-chloro-3,3,3-
trifluoropropene; or the chloro compound is I-chloro-3,3,3-trifluoropropene
and the fluoro compound is 1,3,3,3-tetrafluoropropene; or the chloro
25 compound is 1,1,2-trichloroethane and the fluoro compound is l-chloro-
2,2-difluoroethane.
According to one embodiment, the mixing and vaporizing unit is a
static mixer.
According to one embodiment, the installation comprises:
30 - at least one separating unit fed by the product stream collection
pipe; and
- a fluoro compound collection pipe and a recycling stream
collection pipe at the outlet of the separating unit(s).
According to one embodiment, the recycling stream collection pipe
35 and optionally a hydrofluoric acid supply pipe feed the pipe for supplying
the gas stream comprising hydrofluoric acid.
According to one embodiment, the installation comprises a catalytic
fluorination reactor fed at least partly by the recycling stream collection
pipe, where appropriate with a supply of hydrofluoric acid, the pipe for
supplying the gas stream comprising hydrofluoric acid being derived from
5 the catalytic fluorination reactor.
According to one embodiment, the installation comprises heating
means on the pipe for supplying the liquid stream of chloro compound.
According to one embodiment, the installation comprises heating
means or cooling means on the gas mixture collection pipe.
10 The present invention makes it possible to overcome the drawbacks
of the prior art. It more particularly provides a process for producing fluoro
compounds which limits or avoids the problem of coking of the installation.
This is accomplished by vaporizing the main reagent (chloro
compound intended to be fluorinated) by mixing it with a hot gas stream
15 which contains hydrofluoric acid.
Vaporizing and superheating of the main reagent in a heat
exchanger is thus avoided, this heat exchanger having a very high contact
surface and also hotspots, which are two factors that lead to substantial
coking (the hot metal having a tendency to catalyze coking).
20 Moreover, as a result of this mixing step, the partial pressure of the
chloro compound during its vaporization is relatively moderate, and thus
the vaporization temperature is also relatively moderate, and in any case
below the vaporization temperature in the situation in which the chloro
compound is vaporized independently. This makes it possible especially to
25 limit the risks of degradation of the chloro compound.
Preferably, the gas stream comprising hydrofluoric acid is at a
temperature from 100 to 40OoC, more particularly from 130 to 380°C and
advantageously from 250 to 380°C at the time of its mixing with the liquid
stream of chloro compound.
30 In general, the temperature of the gas stream comprising
hydrofluoric acid, at the time of its mixing with the liquid stream of chloro
compound, is chosen:
- less than or equal to the temperature of the catalytic reaction;
- greater than or equal to the vaporization temperature of the gas
stream comprising hydrofluoric acid, which depends on the
pressure and the composition of this stream (especially the HF
content).
For example, in the context of producing HFC-125 (as described in
greater detail hereinbelow), the temperature of the gas stream comprising
5 hydrofluoric acid may be about 165°C. In the context of producing HFO-
1234yf (as described in greater detail hereinbelow), the temperature of the
gas stream comprising hydrofluoric acid may be from about 320 to 380°C.
BRIEF DESCRIPTION OF THE FIGURES
10
Figure 1 schematically represents one embodiment of the
installation according to the invention.
Figure 2 schematically represents another embodiment of the
installation according to the invention.
15 Figure 3 is a graph illustrating the change in temperature of a feed
stream of the main fluorination reactor after vaporization of the chloro
compound (cf. Example 1). The x-axis gives the flow rate of the gas stream
comprising HF, expressed in t/h; the y-axis gives the temperature of the
stream after mixing with the chloro compound and vaporization thereof,
20 expressed in "C. The points represented by A correspond to an initial
temperature of the chloro compound of 25"C, those represented by m
correspond to an initial temperature of the chloro compound of 70°C and
those represented by 0 correspond to an initial temperature of the chloro
compound of 100°C. The three groups of data marked 10, 20 and 30 on
25 the graph correspond to HFIorganics mole ratios respectively equal to 10,
20 and 30.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
30 The invention is now described in greater detail and in a nonlimiting
manner in the description that follows.
The invention relates to the fluorination of a chloro compound with
hydrofluoric acid, to form a fluoro compound.
The term "chloro compound" means an organic compound
35 comprising one or more chlorine atoms, and the term "fluoro compound"
means an organic compound comprising one or more fluorine atoms.
It is understood that the chloro compound may comprise one or
more fluorine atoms, and that the fluoro compound may comprise one or
more chlorine atoms. In general, the number of chlorine atoms in the fluoro
compound is less than the number of chlorine atoms in the chloro
5 compound; and the number of fluorine atoms in the fluoro compound is
greater than the number of fluorine atoms in the chloro compound.
The chloro compound may be an alkane or an alkene optionally
bearing substituents chosen from F, CI, I and Br (preferably from F and CI),
and comprising at least one CI substituent.
10 The fluoro compound may be an alkane or an alkene optionally
bearing substituents chosen from F, CI, I and Br (preferably from F and CI),
and comprising at least one F substituent.
The chloro compound may especially be an alkane with one or more
chlorine substituents (chlorohydrocarbon or chlorocarbon) or an alkane
15 with one or more chlorine and fluorine substituents
(hydrochlorofluorocarbon or chlorofluorocarbon) or an alkene with-one or
more chlorine substituents (chloroolefin or hydrochloroolefin) or an alkene
with one or more chlorine and fluorine substituents (hydrochlorofluoroolefin
or chlorofluoroolefin).
20 The fluoro compound may especially be an alkane with one or more
fluorine substituents (fluorocarbon or hydrofluorocarbon) or an alkane with
one or more chlorine and fluorine substituents (hydrochlorofluorocarbon or
chlorofluorocarbon) or an alkene with one or more fluorine substituents
(fluoroolefin or hydrofluoroolefin) or an alkene with one or more chlorine
25 and fluorine substituents (hydrochlorofluoroolefin or chlorofluoroolefin).
The chloro compound and the fluoro compound may be linear or
branched, preferably linear.
According to one embodiment, the chloro compound and the fluoro
compound comprise only one carbon atom.
30 According to one embodiment, the chloro compound and the fluoro
compound comprise two carbon atoms.
According to one embodiment, the chloro compound and the fluoro
compound comprise three carbon atoms.
According to one embodiment, the chloro compound and the fluoro
35 compound comprise four carbon atoms.
According to one embodiment, the chloro compound and the fluoro
compound comprise five carbon atoms.
The invention is especially to be applied for the following fluorination
reactions:
- fluorination of perchloroethylene (PER) to pentafluoroethane
5 (HFC-125);
- fluorination of 1 ,I ,I ,2,3-pentachloropropane (HCC-240db) to
. 2-chloro-3,3,3-trifluoropropene (HCFO-1233x9;
- fluorination of 1 ,I ,I ,2,3-pentachloropropane (HCC-240db) to
2,3,3,3-tetrafluoropropene (HFO-1234yf);
10 - fluorination of 1, I1,,3 ,3-pentachloropropane (HCC-240fa) to
1,3,3,3-tetrafluoropropene (HFO-1234ze);
- fluorination of 1 ,I ,I ,3,3-pentachloropropane (HCC-240fa) to 1-
chloro-3,3,3-trifluoropropene (HCFO-1233zd);
- fluorination of 2-chloro-3,3,3-trifluoropropene (HCFO-1233x9 to
15 2,3,3,3-tetrafluoropropene (HFO-1234yf);
- fluorination of 1,1,2,2,3-pentachloropropane (HCC-240aa) to
2,3,3,3-tetrafluoropropene (HFO-1234yf);
- fluorination of 1,1,2,2,3-pentachloropropan(eH CC-240aa) to
2-chloro-3,3,3-trifluoropropene (HCFO-1233x9;
20 - fluorination of 2,3-dichloro-l,l,l-trifluoropropane (HCFC-243db)
to 2,3,3,3-tetrafluoropropene (HFO-1234~9;
- fluorination of 2,3-dichloro-I ,I,I - trifluoropropane (HCFC-243db)
to 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd);
- fluorination of 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db)
25 to 1,3,3,3-tetrafluoropropene (HFO-1234ze);
- fluorination of 2,3-dichloro-l,l,l-trifluoropropane (HCFC-243db)
to 2-chloro-3,3,3-trifluoropropene (HCFO-1233x9;
- fluorination of 1 ,I ,2,3-tetrachloropropene (HCO-1230xa) to
2,3,3,3-tetrafluoropropene (HFO-1234yf);
30 - fluorination of 1 ,I ,2,3-tetrachloropropene (HCO-1230xa) to
2-chloro-3,3,3-trifluoropropene (HCFO-1233x9;
- fluorination of 2,3,3,3-tetrachloropropene (HCO-1230xf) to
2,3,3,3-tetrafluoropropene (HFO-1234yf);
- fluorination of 2,3,3,3-tetrachloropropene (HCO-1230x9 to
35 2-chloro-3,3,3-trifluoropropene (HCFO-1233x9;
- fluorination of 1,1,3,3-tetrachloropropene (HCO-1230za) to 1-
chloro-3,3,3-trifluoropropene (HCFO-1233zd);
- fluorination of 1,1,3,3-tetrachloropropene (HCO-1230za) to
1,3,3,3-tetrafluoropropene (HFO-1234ze);
5 - fluorination of 1,3,3,3-tetrachloropropene (HCO-1230zd) to 1-
chloro-3,3,3-trifluoropropene (HCFO-1233zd);
- fluorination of 1,3,3,3-tetrachloropropene (HCO-1230zd) to
1,3,3,3-tetrafluoropropene (HFO-1234ze);
- fluorinationof I-chloro-3,3,3-trifluoropropene (HCFO-1233zd) to
10 1,3,3,3-tetrafluoropropene (HFO-I 234ze);
- fluorination of 1,1,2-trichloroethane to 1-chloro-2,2-
difluoroethane (HCFC-142);
- fluorination of 1,2-dichloroethylene to 1-chloro-2,2-
difluoroethane (HCFC-142)
15 The conversion of the chloro compound into a fiuoro compound may
be a direct conversion (with only one reaction step or with only one set of
reaction conditions) or an indirect conversion (with two or more than two
reaction steps or using two or more than two sets of reaction conditions).
The fluorination reaction may be performed:
20 - with an HFIchloro compound mole ratio of from 3:l to 150:1,
preferably from 4:l to 100:l and more particularly preferably from
5:l to 50:l;
- with a contact time of from 1 to 100 s, preferably from 1 to 50 s
and more particularly 2 to 40 s (volume of catalyst divided by the
total entering stream, adjusted to the operating temperature and
pressure);
- at an absolute pressure ranging from 0.1 to 50 bar, preferably
from 0.3 to 15 bar;
- at a temperature (temperature of the catalytic bed) of from 100 to
30 500°C, preferably from 200 to 450°C and more particularly from
300 to 400°C.
In order to avoid rapid deactivation of the catalyst during the
reaction, an oxidizing agent (for example oxygen or chlorine) may be
added, for example in an oxidizing agenuorganic compounds mole ratio of
35 from 0.005 to 2, preferably from 0.01 to 1.5. Use may be made, for
example, of a stream of pure oxygen or of pure chlorine, or an
oxygenlnitrogen or chlorinelnitrogen mixture.
The catalyst used may be based, for example, on a metal
comprising an oxide of a transition metal or a derivative or a halide or an
oxyhalide of such a metal. Examples that may be mentioned include FeC13,
5 chromium oxyfluoride, chromium oxides (optionally subjected to fluorination
treatments), chromium fluorides, and mixtures thereof. Other possible
catalysts are catalysts supported on charcoal, antimony-based catalysts
and aluminum-based catalysts (for example AIF3 and AI2O3, alumina
oxyfluoride and alumina fluoride).
10 Use may generally be made of a chromium oxyfluoride, an
aluminum fluoride or oxyfluoride, or an optionally supported catalyst
containing a metal such as Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge, Sn, Pb, Mg or
Sb.
Reference may be made in this respect to WO 20071079 431 (on
15 page 7, lines 1-5 and 28-32), to EP 939 071 (paragraph [0022]), to WO
20081054 781 (on page 9, line 22 to page 10, line 34) and to WO 20081040
969 (claim I), to which reference is expressly made.
Before its use, the catalyst is preferably subjected to activation with
air, oxygen or chlorine andlor with HF.
20 Before its use, the catalyst is preferably subjected to activation with
air or oxygen and HF at a temperature of from 100 to 500"C, preferably
from 250 to 500°C and more particularly from 300 to 400°C. The activation
time is preferably from 1 to 200 hours and more particularly from 1 to 50
hours.
25 This activation may be followed by a final fluorination activation step
in the presence of an oxidizing agent, HF and organic compounds.
The HFlorganic compounds mole ratio is preferably from 2 to 40 and
the oxidizing agentlorganic compounds mole ratio is preferably from 0.04 to
25. The final activation temperature is preferably from 300 to 400°C and its
30 duration is preferably from'6 to 100 hours.
The catalyst is preferably based on chromium and it is more
particularly a mixed catalyst comprising chromium.
According to one embodiment, a mixed catalyst comprising
chromium and nickel is used. The CrINi mole ratio (on the basis of the
35 metal element) is generally from 0.5 to 5, for example from 0.7 to 2, for
example about I. The catalyst may contain from 0.5% to 20% by weight of
chromium, and from 0.5% to 20% by weight of nickel, preferably from 2% to
10% of each.
The metal may be present in metallic form or in the form of a
derivative, for example an oxide, halide or oxyhalide. These derivatives are
5 preferably obtained by activation of the catalytic metal.
The support is preferably constituted with aluminum, for example
alumina, activated alumina or aluminum derivatives, such as aluminum
halides and aluminum oxyhalides, described, for example, in US 4 902
838, or obtained via the activation process described above.
10 The catalyst may comprise chromium and nickel in an optionally
activated form, on a support that has optionally been subjected to
activation.
Reference may be made to WO 2009/118 628 (especially on page
4, line 30 to page 7, line 16), to which reference is expressly made herein.
15 Another preferred embodiment is based on a mixed catalyst
containing chromium and at least-one element chosen from Mg and Zn.
The atomic ratio of Mg or ZnlCr is preferably from 0.01 to 5.
With reference to Figure 1, an embodiment of the invention is now
described in the particular case of a process for producing HFO-1234yf
20 from HCC-240db, it being understood that it is similarly valid for other
couples of chloro compoundslfluoro compounds.
The installation according to the invention comprises a pipe for
supplying the liquid stream of HCC-240db 2 and a pipe for supplying the
gas stream comprising HF 5, which feed a catalytic fluorination reactor 8.
25 The pipe for supplying the liquid stream of HCC-240db 2 originates from a
reserve of liquid HCC-240db 1. The pipe for supplying the gas stream
comprising HF 5 may transport a stream of pure HF (optionally in
combination with an oxidizing agent as described above) or, alternately, a
mixture of HF and of organic compounds, especially of chloro andlor fluoro
30 organic compounds, as is the case in the illustrated example, and as will be
described in greater detail below.
A mixing and vaporizing unit 4 is fed both by the pipe for supplying
the liquid stream of HCC-240db 2 and the pipe for supplying the gas
stream comprising HF 5. This unit is adapted to mix the gas stream and the
35 liquid stream. It is preferably a static mixer so as to allow a process of
continuous type. In this unit, the gas stream comprising HF yields heat to
the liquid stream of HCC-240db, which allows vaporization of the HCC-
240db.
The mixture of HCC-240db, of HF and optionally of additional
compounds is collected in a gas mixture collection pipe 6 at the outlet of
5 the mixing and vaporizing unit 4, which transports the mixture to the
catalytic fluorination reactor 8.
The HCC-240db may undergo a preliminary heating step before
mixing with the gas stream comprising HF. In this case, this preliminary
heating is performed at a temperature below the vaporization temperature
10 of HCC-240db (and at a temperature below the degradation or
decomposition temperature of this compound). To this end, heating means
3 may be provided on the pipe for supplying the liquid stream of HCC-
240db 2.
Between the mixing of HCC-240db with the stream comprising HF
15 and the fluorination reaction, additional heating of the mixture or, on the
contrary, cooling of the mixture may be provided, depending on the case,
by providing either heating means or, as illustrated in the figure, cooling
means 7 on the gas mixture collection pipe 6. The choice of heating or
cooling depends on the desired temperature for the fluorination reaction, in
20 comparison with the temperature of the gas mixture obtained from the
mixing and vaporizing unit 4.
A product stream collection pipe 9 is connected at the outlet of the
catalytic fluorination reactor 8. This collection pipe feeds a separating unit
10 (or several successive separating units) making it possible especially to
25 separate the product of interest (fluoro compound, in this instance HFO-
1234yf) from the rest of the product stream. In this regard, use may be
made especially of one or more distillation columns, or decantation,
extraction or washing units or the like. This product of interest is recovered
in a fluoro compound collection pipe 11 at the outlet of the separating unit
30 10. Moreover, a recycling stream is recovered in a recycling stream
collection pipe 12. Other undesirable products may moreover be removed
at this stage (especially the hydrochloric acid generated during the
fluorination reaction).
The recycling stream may especially contain unreacted reagents,
35 namely HF and chloro compound (in this instance HCC-240db). It may also
contain side products derived from the reaction, i.e. fluoro products
obtained by fluorination of the chloro compound (HCC-240db) and other
than the desired fluoro compound. In the illustrated case, the recycling
stream especially contains HCFO-1233xf, and optionally HFC-245cb
(1, I, I,2 ,2-pentafluoropropane), obtained by fluorination of HCC-240db.
5 According to a possible embodiment, the recycling stream may be
returned directly into the catalytic fluorination reactor 8. According to
another possible embodiment, it may undergo a completely separate
treatment, or even separate upgrading. According to another possible
embodiment, it is partially returned to the catalytic fluorination reactor 8.
10 According to another embodiment, which is the one illustrated here,
the recycling stream undergoes an additional fluorination before being
returned to the main catalytic fluorination reactor 8.
Thus, the recycling stream collection pipe 12 feeds an additional
catalytic fluorination reactor 16. An HF supply pipe 13 may, where
15 appropriate, as illustrated, be connected thereto so as to supply fresh HF.
An oxidizing agent supply pipe 14 may also, where appropriate, as
illustrated, be connected to the recycling stream collection pipe 12 so as to
provide a supply of oxidizing agent capable of maintaining the catalytic
activity of the catalyst.
20 Heating and vaporizing means 15 may be provided on the recycling
stream collection pipe 12 so as to bring the stream to the desired
temperature for the additional fluorination reaction, which is performed in
the additional catalytic fluorination reactor 16.
In the illustrated example, the pipe for supplying the gas stream
25 comprising HF 5 (described previously) is derived directly from the
additional catalytic fluorination reactor 16. Thus, the gas stream comprising
HF contains, besides HF (and, where appropriate, oxidizing agent), fluoro
products derived from the additional fluorination reaction.
A supply of fresh HF andlor a supply of oxidizing agent may be
30 added into the pipe for supplying the gas stream comprising HF 5, if need
be.
The principle of a production process comprising two distinct
catalytic fluorination steps, the feeding with chloro reagent (HCC-240db)
being performed between these two steps, is described in detail in WO
35 20131088 195, to which it is referred by way of reference.
In the preceding description, the gas stream comprising HF (which is
used to vaporize the liquid stream of chloro compound) corresponds to a
stream derived from an additional fluorination reaction of a recycling
stream. Other variants are possible:
- the gas stream comprising HF may be a stream derived from an
5 additional fluorination reaction of a recycling stream,
supplemented with additional HF andlor additional oxidizing
agent;
- the gas stream comprising HF may be directly a recycling stream
or a partial recycling stream (without the additional fluorination
10 reaction step);
- the gas stream comprising HF may be directly a recycling stream
(without the additional fluorination reaction step), supplemented
with additional HF andlor additional oxidizing agent;
- the gas stream comprising HF may be a stream of fresh HF
15 optionally comprising fresh oxidizing agent.
In the latter case, if a recycling stream is present; it may be
introduced after the step of mixing the gas stream comprising HF with the
liquid stream of chloro compound; and if an additional fluorination reaction
of a recycling stream is performed, the stream derived from this reaction
20 may be introduced after the step of mixing the gas stream comprising HF
with the liquid stream of chloro compound.
Another embodiment is now described with reference to Figure 2: it
is a process for producing HFC-125 from PER (and also the installation for
implementing said process).
25 The installation comprises a pipe for supplying the gas stream
comprising HF 25 and a pipe for supplying the liquid stream of PER 21,
which both feed a mixing and vaporizing unit 22, which is a static mixer. A
gas mixture collection pipe 23 is connected at the outlet of said unit, and
feeds one or a series of several fluorination reactors (not shown).
3 0 Heating means 26a, 26b, 26c are provided on the pipe for supplying
the gas stream comprising HF 25. Heating means 24a, 24b are provided
on the gas mixture collection pipe 23.
According to one embodiment, the gas stream comprising HF is
obtained by heating and, where appropriate, vaporizing a recycling stream
35 collected after treatment and separation of a product stream derived from
the catalytic fluorination reaction.
Some of the heating means 26a, 24a used may be heat-saving
exchangers.
The important parameters to be taken into account generally in the
implementation of the process of the invention are the following:
5 - the flow rate of gas stream comprising HF must be higher than
the flow rate of chloro compound, and sufficiently high relative to
the latter so as to allow total vaporization of the chloro compound
and to avoid partial condensation of the gas stream comprising
HF; thus, preferably, the ratio of mass flows between the gas
stream comprising HF and the stream of chloro compound is
from I to 30, preferably from 2.2 to 25 and more particularly
preferably from 1.5 to 20;
- the temperature of the gas stream comprising HF must be
sufficiently high, for the same reasons (it must in any event be
higher than the vaporization temperature of the chloro
compound, at the pressure under consideration);
- the differential between the temperature of the gas stream
comprising HF and the temperature of the gas mixture after
vaporization of the chloro compound must remain relatively low,
20 preferably less than or equal to 50°C, or less than or equal to
30°C or 25°C.
When the temperature of the gas stream comprising HF is relatively
low (for example of the order of 150 or 20OoC), a relatively high mass flow
rate (gas streamlliquid stream) ratio is necessary so as to ensure total
25 vaporization of the chloro compound. However, the resulting temperature
differential is relatively low. In this regime, the heat generated by
oligomerization of the HF is used to vaporize the chloro compound.
When the temperature of the gas stream comprising HF is relatively
high (for example of the order of 250 or 300°C), a lower mass flow rate
30 ratio is necessary, but the temperature differential obtained is relatively
high. In this regime, the HF vapor is not in oligomeric form, and the heat of
vaporization of the chloro compound is provided by the cooling of the
superheated HF.
35 EXAMPLES
The examples that follow illustrate the invention without limiting it.
Example 1 - studv of the lowerina of the temperature of the HF stream
associated with mixinq with the chloro compound
For this study, a fluorination reaction of HCC-240db to HFO-1234yf
is considered, according to the scheme of Figure 1.
A productivity of HFO-1234yf of 1600 kglh, a fluorination reaction
(reactor 8) performed at 4, 5 or 7 bar absolute, depending on the case, an
HFIchloro compound mole ratio of 10, 20 or 30, depending on the case,
and a degree of conversion of HCFO-1233xf of 60% or 70%, depending on
the case, are considered. The feed rate of HCC-240db is 3100 kglh in all
cases.
The preliminary fluorination reaction (reactor 16) is considered to be
performed at a temperature of 350°C, and the gas stream comprising HF
(pipe 5) is thus considered to be at this temperature of 350°C.
Three conditions concerning the temperature of the stream of HCC-
240db are considered: 25°C (absence of preheating of the stream), 70°C or
100°C.
Starting with all of these conditions, the temperature of the stream
after mixing between the stream comprising HF and the liquid stream of
HCC-240db is calculated in each case, from the available data regarding
the vapor pressure as a function of the temperature for HCC-240db. The
results are given in Figure 3.
It is found that the influence of preheating of the stream of HCC-
240db on the final temperature is relatively small (difference of 2.4 at 8°C
on the final temperature of the stream after mixing, depending on whether
the stream of HCC-240db is or is not preheated). The need to provide
additional heating (or, on the contrary, cooling) of the mixture before the
reaction depends on the desired reaction temperature.
It is found, in general, that the decrease in temperature associated
with the mixing with HCC-240db and vaporization thereof is moderate and
compatible with the implementation of the process.
Example 2 - studv of the mass flow rate ratio required between the gas
stream comprising HF and the stream of chloro compound
For this study, the same basic conditions as in Example 1 are used,
taking a pressure of 7 bar absolute. Streams of HF (pure) at various
temperatures, namely 150, 200, 250 or 30OoC, are envisaged here.
Depending on the case, a greater or lesser decrease in temperature
following mixing with HCC-240db (noted AT, as an absolute value) is
accepted, and the corresponding mass flow rate ratio (R) (mass flow rate of
5 gas stream comprising HF to mass flow rate of HCC-240db) is deduced
therefrom.
The limit values of AT and R allowing total vaporization of the HCC-
240db (without leading to condensation of the gas stream comprising HF)
are also calculated. The results are collated in the table below:
10
Example 3 - Pilot test
A gas stream derived from a fluorination reactor comprising HF is
mixed with a preheated liquid stream of 240db. The flow rate of the gas
15 stream comprising HF derived from the fluorination reactor is from 20 to 50
kglh. This gas stream is at a temperature of from 320°C to 350°C and at a
pressure of 3 to 5 bara. The flow rate of the liquid stream of 240db is from
3 to 4 kglh. This liquid stream of 240db is preheated to a temperature of
100°C to 120°C at a pressure of 4 to 6 bara.
20 When the two streams are mixed, the liquid stream of 240db is
instantaneously vaporized by the stream comprising HF and the
temperature of the gas stream resulting from the mixing of these two
streams is from 280°C to 330°C at 3 to 5 bara. This resulting stream may
optionally be reheated to a temperature of 350°C to 380°C before feeding
25 another fluorination reactor in which the fluorination of 240db to 1233xf is
WO 2015/055927
performed.
CLAIMS
1 A process for producing a fluoro compound, involving:
- supplying a gas stream comprising hydrofluoric acid;
- supplying at least one liquid stream of chloro compound
and vaporizing said compound by mixing with said gas
stream, the resulting mixture being a gaseous mixture;
- catalytically reacting the chloro compound with the
hydrofluoric acid in the gas phase and collecting a
product stream.
2. The process as claimed in claim 1, in which:
- the chloro compound is a chlorocarbon, a
chlorohydrocarbon, a chlorofluorocarbon, a
hydrochlorofluorocarbon, a chloroolefin, a
hydrochloroolefin, a chlorofluoroolefin or a
hydrochlorofluoroolefin; and in which the fluoro compound
is a fluorocarbon, a fluorohydrocarbon, a
chlorofluorocarbon, a hydrochlorofluorocarbon, a
fluoroolefin, a hydrofluoroolefin, a chlorofluoroolefin or a
hydrochlorofluoroolefin; and
- preferably, the chloro compound is chosen from 1,1,2-
trichloroethane, 1 ,I ,I ,2(3-pentachloropropane, I ,I , I ,3,3-
pentachloropropane, 1 ,I ,2,2,3-pentachloropropane, 2,3-
dichloro-I ,I ,I-trifluoropropane, perchloroethylene, 1.2-
dichloroethylene, 1, I,2 ,3-tetrachloropropene, 2,3,3,3-
tetrachloropropene, 1 ,I ,3,3-tetrachloropropene, 1,3,3,3-
tetrachloropropene, 2-chloro-3,3,3-trifluoropropene and 1-
chloro-3,3,3-trifluoropropene, and mixtures thereof;
- preferably, the fluoro compound is chosen from
pentafluoroethane, I-chloro-2,2-difluoroethane, 1,3,3,3-
tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 2-chloro-
3,3,3-trifluoropropene and I-chloro-3,3,3-trifluoropropene,
and mixtures thereof:
- more particularly preferably, the chloro compound is
perchloroethylene and the fluoro compound is
pentafluoroethane, or the chloro compound is 1,1,1,2,3-
pentachloropropane and the fluoro compound is 2,3,3,3-
tetrafluoropropene.
The process as claimed in claim 1 or 2, in which the mixing of
the liquid stream of chloro .compound with the gas stream
comprising hydrofluoric acid is performed in a static mixer.
The process as claimed in one of claims 1 to 3, comprising
one or more steps for separation of the product stream,
making it possible to collect, on the one hand, a stream of the
fluoro compound and, on the other hand, a recycling stream.
The process as claimed in claim 4, in which the recycling
stream provides the gas stream comprising hydrofluoric acid,
optionally after supplying hydrofluoric acid.
The process as claimed in claim 4, comprising a step of
catalytic fluorination of the recycling stream, where
appropriate with a supply of hydrofluoric acid, the gas stream
comprising hydrofluoric acid being collected on conclusion of
this fluorination step.
The process as claimed in one of claims 1 to 6, comprising a
step of heating the liquid stream of chloro compound to a
temperature below its vaporization temperature.
The process as claimed in one of claims 1 to 7, comprising,
after the step of mixing the liquid stream of chloro compound
with the gas stream comprising hydrofluoric acid, and before
the step of catalytic reaction of the chloro compound with the
hydrofluoric acid:
- a step of heating the mixture; or
- a step of cooling the mixture.
9. An installation for producing a fluoro compound, comprising:
- a pipe for supplying a liquid stream of chloro compound
(2);
- a pipe for supplying a gas stream comprising hydrofluoric
acid (5);
- a mixing and vaporizing unit (4) fed by the pipe for
supplying the liquid stream of chloro compound (2) and
the pipe for supplying the gas stream comprising
hydrofluoric acid (5);
- a pipe for collecting a gas mixture (6) at the outlet of the
mixing and vaporizing unit (4);
- a catalytic fluorination reactor (8) fed by the pipe for
collecting the gas mixture (6); and
- a pipe for collecting the product stream (9) at the outlet of
the catalytic fluorination reactor (8).
10. The installation as claimed in claim 9, in which:
- the chloro compound is a chlorocarbon, a
chlorohydrocarbon, a chlorofluorocarbon, a
hydrochlorofluorocarbon, a chloroolefin, a
hydrochloroolefin or a hydrochlorofluoroolefin; and in
which the fluoro compound is a fluorocarbon, a
fluorohydrocarbon, a chlorofluorocarbon, a
hydrochlorofluorocarbon, a fluoroolefin, a
hydrofluoroolefin or a hydrochlorofluoroolefin; and
- preferably, the chloro compound is chosen from 1,1,2-
trichloroethane, 1 , I, 1,2,3-pentachloropropaneI,, I, I,3 ,3-
pentachloropropane, 1, I, 2,2,3-pentachloropropane,2 ,3-
dichloro-I ,I ,I-trifluoropropane, perchloroethylene, 1,2-
dichloroethylene, 1 , I ,2,3-tetrachloropropene, 2,3,3,3-
tetrachloropropene, 1 ,I ,3,3-tetrachloropropene, 1,3,3,3-
tetrachloropropene, 2-chloro-3,3,3-trifluoropropene and 1-
chloro-3,3,3-trifluoropropene, and mixtures thereof;
- preferably, the fluoro compound is chosen from
pentafluoroethane, I-chloro-2,2-difluoroethane, 1,3,3,3-
tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 2-chloro3,3,3-
trifluoropropene and 1-chloro-3,3,3-trifluoropropene,
and mixtures thereof;
- more particularly preferably, the chloro compound is
perchloroethylene and the fluoro compound is
pentafluoroethane, or the chloro compound is 1,1,1,2,3-
pentachloropropane and the fluoro compound is 2,3,3,3-
tetrafluoropropene.
The installation as claimed in claim 9 or 10, in which the
mixing and vaporizing unit (4) is a static mixer.
The installation as claimed in one of claims 9 to 11,
comprising:
- at least one separating unit (10) fed by the product stream
collection pipe (9); and
- a fluoro compound collection pipe (11) and a recycling
stream collection pipe (12) at the outlet of the separating
unit(s) (lo).
The installation as claimed in claim 12, in which the recycling
stream collection pipe (12) and optionally a hydrofluoric acid
supply pipe (13) feed the pipe for supplying the gas stream
comprising hydrofluoric acid (5).
The installation as claimed in claim 12, comprising a catalytic
fluorination reactor (16) at least partly fed by the recycling
dream collection pipe (12), where appropriate with a supply
of hydrofluoric acid, the pipe for supplying the gas stream
comprising hydrofluoric acid (5) being derived from the
catalytic fluorination reactor (16).
The installation as claimed in one of claims 9 to 14,
comprising heating means (3) on the pipe for supplying the
liquid stream of chloro compound (2).
16. The installation as claimed in one of claims 9 to 15,
comprising heating means or cooling means (9) on the gas
mixture collection pipe (6).