PROCESS FOR PRODUCING 1-CHLOR0-2,2-DIFLUOROETHANE
The present invention relates to the field of saturated fluorohydrocarbons. The
invention relates more particularly to the manufacture of 1-chloro-2,2-
5 difluoroethane from 1, I ,2-trichloroethane.
1-Chloro-2,2-difluoroethane (HCFC-142) is not only known as an expander in
the manufacture of foams, but also as a starting material in the manufacture of
pharmaceutical or agrochemical compounds.
It is know~ practice to prepare 1-chloro-2,2-difluoroethane by reacting I, I ,2-
10 trichloroethane (HCC-140) with hydrofluoric acid in the liquid· phase, at a
temperature ofbetwl:'en 30 and 180°C and in the pr<>sence of a Lewis acid as catalyst
(FR 2 783 821). The preparation of HCFC-142 may also be performed in the gas
phase at a temperature of between 120 and 400°C, in the presence of a bulk or
supported chromium-based catalyst(FR 2 783 820 and EP I 008 575).
15 Moreover, WO 2013/053800 describes the preparation of catalysts for the
fluorination of HCC-140 and 1,2-dichloroethylene (1130) with hydrofluoric acid,
said catalysts being obtained by co-depositing ferric chloride and magnesium
chloride on chromium oxide and alumina oxide or by co-depositing chromium
nitrate and nickel nitrate on active charcoal or by doping alumina with zinc chloride.
20 It is observed from WO 2013/053800 that all the tests were perfonned over a
very short time (maximum of 6 hours) and that the fluorination ofHCC-140 in the
majority of the cases leads predominantly to 1,2-dichloroethylene (isomers not
specified).
The Applicant has developed a process for manufacturing 1-chloro-2,2-
25 difluoroethane which does not have the drawbacks of the prior art.
The present invention provides a process for manufacturing 1-chloro-2,2-
difluoroethane from 1,1,2-trichloroethane and/or 1,2-dichloroethylene, comprising
(i) at least one step during which 1,1,2-trichloroethane and/or 1,2-dichloroethylene
react(s) with hydrofluoric acid in the gas phase in the presence of an oxidizing agent,
30 of a fluorination catalyst, to give a stream comprising 1-chloro-2,2cdifluoroethane,
hydrochloric acid, hydrofluoric acid and at least one compound C chosen from
1-chloro-2-fluoroethylenes (cis and trans), I ,2-dichloro-2-fluoroethane and
optionally unreacted I, I ,2-trichloroethane and/or I ,2-dichloroethylene.
One subject of the present invention is thus a process for manufacturing
35 1-chloro-2,2-difluoroethane from I, I ,2-trichloroethane, comprising (i) at least one
step during which 1, I ,2-trichloroethane reacts with hydrofluoric acid in the gas
- 2-
phase in the presence of an oxidizing agent, of a fluorination catalyst, to give a
stream comprising I -chloro-2,2-difluoroethane, hydrochloric acid, hydrofluoric acid
and at least one compound C chosen from 1,2-dichloroethylenes (cis and trans),
1-chloro-2-fluoroethylenes (cis and trans), 1 ,2-dichloro-2-fluoroethane and
5 optionally unreacted 1,1,2-trichloroethane; (ii) at least one step of separating the
compounds derived from the reaction step to give a stream A comprising
hydrochloric acid and a stream B comprising hydrofluoric acid, 1-chloro-2,2-
difluoroethane, at least one compound C and optionally 1,1,2-trifluoroethane; (iii) at
least one step ~'f separating the stream B to give an organic phase comprising
10 1-chloro-2,2-difluoroethane, at least one compound C and optionally unreacted
1,1,2-trichloreethane and amm-oFganic phase predominantly comprising HF, (iv) at
least one step of separating the 1-chloro-2,2-difluoroethane from the organic phase
obtained in (iii); (v) optional recycling into step (i) of the organic phase after the
separation of step (iv); and (vi) optional recycling into step (i) of the non-organic
15 phase derived from step (iii).
After separating out the 1-chloro-2,2-difluoroethane, the organic phase
preferably comprises 1-chloro-2-fluoroethylene, I ,2-dichloroethylenes (cis and
trans) and 1,2-dichloro-2-fluoroethane.
According to one embodiment, before recycling into step (i), the non-organic
20 phase is purified such that the HF content is greater than or equal to 90% by weight.
Preferably, this purification comprises at least one distillation, advantageously
performed at a temperature of between -23 and 46°C and an absolute pressure of
between 0.3 and 3 bar.
Preferably, the separation step (ii) comprises at least one distillation,
25 advantageously performed at a temperature of between -60 and 89°C and an absolute
pressure of between 3 and 11 bar.
Preferably, the separation step (iii) comprises at least one decantation step,
advantageously performed at a temperature of between -20 and 1 0°C.
Preferably, the separation step (iv) comprises at least one distillation,
30 advantageously performed at a temperature of between 35 and 79°C and an absolute
pressure of between 1 and 4 bar.
This separation step may be performed by extractive azeotropic distillation,
liquid/liquid extraction or membrane separation.
The temperature of the reaction step is preferably between 150 and 400°C,
35 advantageously between 200 and 350°C.
The pressure at which the fluorination reaction is performed is preferably
- 3 -
between I and 20 bar absolute, advantageously between 3 and 15 bar absolute.
The amount of hydrofluoric acid used in the reaction is preferably between 5
and 40 mol and advantageously between 10 and 30 mol per mole ofHCC-140 .and/or
I ,2-dichloroethylene.
5 The contact time, defmed as being the volume of catalyst/total gas flow rate
by volume at the reaction temperature and pressure is preferably between 2 and 100
seconds, advantageously between 2 and 50 seconds.
The oxidizing agent, in pure form or mixed with nitrogen, maybe chosen from
oxygen and chl~fine. Chlorine is preferably chosen.
10 The amount of oxidizing agent used is preferably between 0.01 mol% to
0,2 mol% per mole ofHCC-140 and/orl,2-dichloroethylene.
The catalyst used may be in bulk or supported form. The catalyst may be based
on a metal, especially a transition metal or an oxide, halide or oxyhalide derivative
of such a metal. Examples that may be mentioned are especially FeCh, chromium
15 oxyfluoride, NiCh and CrF,, and mixtures thereof.
Supported catalysts that may be mentioned include those supported on
charcoal or based on magnesium, such as magnesium derivatives, especially halides
such as MgF2 or magnesium oxyhalides such as oxyfluorides or based on aluminum
such as alumina, activated alumina or aluminum derivatives, especially halides, such
20 as AIF 3 or aluminum oxyhalides such as oxyfluoride.
25
The catalyst may also comprise co-catalysts chosen from Co, Zn, Mn, Mg, V,
Mo, Te, Nb, Sb, Ta, P, Ni, Zr, Ti, Sn, Cu, Pd, Cd, Bi and rare-earth metals or
mixtures thereof. When the catalyst is based on chromium, Ni, Mg and Zn are
advantageously chosen as co-catalyst.
The co-catalyst/catalyst atomic ratio is preferably between 0.01 and 5.
Chromium-based catalysts are particularly preferred.
The catalyst used in the present invention may be prepared by coprecipitation
of the corresponding salts optionally in the presence ofa support.
The catalyst may also be prepared by co milling of the corresponding oxides.
30 Prior to the fluorination reaction, the catalyst is subjected to a step of activation
with HF at a temperature preferably between 100 and 450°C, advantageously
between 200 and 300°C for a time of between 1 and 50 hours.
Besides the treatment with HF, the activation may be performed in the
presence of the oxidizing agent.
35 The activation steps may be performed at atmospheric pressure or at a pressure
of up to 20 bar.
-4-
According to a preferred mode of the invention, the support may be prepared
using high-porosity alumina. In a first step, the alumina is converted into aluminum
fluoride or a mixture of aluminum fluoride and alumina, by fluorination using air
and hydrofluoric acid, the degree of conversion of the alumina into aluminum
5 fluoride depending essentially on the temperature at which the fluorination of the
alumina is performed (in general between 200°C and 450°C, preferably between
250°C and 400°C). The support is then impregnated using aqueous solutions of salts
of chromium, nickel and optionally a rare-earth metal, or using aqueous solutions of
chromic acid, offiickel or zinc salts, and optionally of rare-earth metal salts or oxides
10 and methanol (serving as chromium-reducing agent). As chromium, nickel or zinc
and rare-earth metal salts, use may be made of chlorides or other salts, for instance
nickel and rare-earth metal oxalates, forrnates, acetates, nitrates and sulfates or
dichromate, provided that these salts are soluble in the amount of water that can be
absorbed by the support.
15 The catalyst may also be prepared by direct impregnation of alumina (which
is generally activated) using solutions of the chromium, nickel or zinc compounds,
and optionally the rare-earth metal compounds, mentioned above. In this case, the
conversion of at least part (for example 70% or more) of the alumina into aluminum
fluoride or aluminum oxyfluoride takes place during the step of activation of the
20 metal of the catalyst.
The activated aluminas that may be used for the preparation of the catalyst are
well-known, commercially available products. They are. generally prepared by
calcination of alumina hydrates (aluminum hydroxides) at a temperature of between
300°C and 800°C. The aluminas (activated or non-activated) may contain large
25 amounts (up to I 000 ppm) of sodium without this harming the catalytic performance.
Preferably, the catalyst is conditioned or activated, i.e. converted into
constituents that are active and stable (with respect to the reaction conditions) via a
preliminary "activation" operation. This treatment may be performed either "in situ"
(in the fluorination reactor) or in suitable apparatus designed to withstand the
30 activation conditions.
After impregnation of the support, the catalyst is dried at a temperature of
between 1 00°C and 350°C, preferably 220°C to 280°C, in the presence of air or
nitrogen.
The dried catalyst is then activated in one or two steps with hydrofluoric acid,
35 optionally in the presence of an oxidizing agent. The duration of this fluorinationmediated
activation step may be between 6 and I 00 hours and the temperature
- 5-
between 200 and 400°C.
A subject of the present invention is also a composition of the azeotropic or
quasi-azeotropic type comprising 1-chloro-2,2-difluoroethane and trans-! ,2-
dichloroethylene.
5 Preferably, the azeotropic or quasi-azeotropic composition comprises
80 mol% to 95 mol% of 1-chloro-2,2-difluoroethane and from 5 mol% to 20 mol%
of trans-! ,2-dichloroethylene.
Advantageously, the azeotropic or quasi-azeotr?pic composition has a boiling
point of betwee~'·32 and I f9°C at a pressure of between 1 and I 0 bar abs.
I 0 The azeotropic composition may be obtained by extractive azeotropic
distillation, liquid/liquid extraction or membrane separation.
EXAMPLES
Experimental procedure:
15 HCC-140 and optionally I ,2-dichloroethylene and HF are fed separately into
a monotubular Inconel reactor, heated by means of a fluidized alumina bath.
The pressure is regulated by means of a regulation valve located at the reactor
outlet. The gases derived from the reaction are analyzed by gas chromatography.
The catalyst is first dried under a stream of nitrogen at 250°C and the nitrogen
20 is then gradually replaced with HF to terminate the activation with pure HF (0.5
mol/hour) at 350°C for 8 hours.
Example 1:
The catalyst used is a chromium oxide (Cr20 3). 35 g are activated as described
above. HCC-140 and HF are then fed in at a mole ratio of 1:8 (10 g/hour ofHF), at
25 230°C, 11 bar abs, with a contact time of 65 seconds.
The yield ofFI42 is 70% after 5 hours. After 30 hours, the yield is less than
30%.
Example2:
The catalyst used is a chromium oxide (Cr203) as in Example 1. 55 g are
30 activated as described above. HCC-140, HF and chlorine are then fed in at an HCC-
140/HF/chlorine mole ratio of 1:9:0.08 (17 g/hour ofHF), at 230°C, II bar abs, with
a contact time of 54 seconds.
The yield ofF142 is 60% after 5 hours. After 100 hours, the yield is 62%.
Example3:
35 The catalyst used is a chromium oxide (Cr203) as in Example 1. 35 g are
activated as described above. HCC-140, HF and chlorine are then fed in at an HCC-
6-
140/HF/ch!orine mole ratio of I :20:0.08 (30 g/hour ofHF), at 225°C, 3 bar abs, with
a contact time of 4 seconds.
The yield ofF 142 is 50% stable over a period of 500 hours.
Example 4:
5 The catalyst used is a chromium oxide (Cr203) supported on alumina. 27 g are
activated as described above. HCC-140 and HF are then fed in at an HCC-140/HF
mole ratio of 1:8 (10 g/hour ofHF), at 235°C, II bar abs, with a contact time of 45
seconds.
The yield i'lf F142 is '70% after 5 hours. After 30 hours, the yield is less than
10 30%.
Example 1 2 3 4
Catalyst
Bulk Cr Bulk Cr Bulk Cr Cr oxide on
oxide oxide oxide alumina
Amount (g) 35 55 35 27
HF/T112 mole ratio 8 9 20 8
HF (g/hour) 10 17.5 30 10
Chlorine/T112 mole ratio 0 0.08 0.08 0
T (°C) 230 230 225 235
P (bar abs) 11 II 3 II
Contact time (seconds) 65 54 4 45
Yield (%) after 5 hours 70 60 53 70
Yield(%) after 30 hours <30 61 <30
Yield (%) after 100 hours <10 62
Yield(%) after 500 hours 50
- 7-

CLAIMS
1. A process for manufacturing 1-ch1oro-2,2-difluoroethane from.1, 1,2-
trichloroethane and/or I ,2-dichloroethylene, comprising at least one step during
5 which 1,1,2-trichloroethane and/or 1,2-dichloroethylene react(s) with hydrofluoric
acid in the gas phase in the presence of an oxidizing agent, of a fluorination catalyst,
to give a stream comprising 1-chloro-2,2-difluoroethane, hydrochloric acid,
hydrofluoric acid and at least one compound C chosen from 1-chloro-2-
fluoroethylenes •:· (cis and' trans), 1 ,2-dichloro-2-fluoroethane and optionally
10 unreacted 1,1,2-trichloroethane and/or 1,2-dichloroethylene.
2. A process for manufacturing 1-chloro-2,2-difluoroethane from 1,1,2-
trichloroethane, comprising (i) at least one step during which 1, 1 ,2-trichloroethane
reacts with hydrofluoric acid in the gas phase in the presence of an oxidizing agent,
15 of a fluorination catalyst, to give a stream comprising 1-chloro-2,2-difluoroethane,
hydrochloric acid, hydrofluoric acid and at least one compound C chosen from 1 ,2-
dichloroethylenes (cis and trans), 1-chloro-2-fluoroethylenes (cis and trans), 1,2-
dichloro-2-fluoroethane and optionally unreacted 1,1,2-trichloroethane; (ii) at least
one step of separating the compounds derived from the reaction step to give a stream
20 A comprising hydrochloric acid and a stream B comprising hydrofluoric acid, 1-
chloro-2,2-difluoroethane, at least one compound C and optionally 1,1,2-
trifluoroethane; (iii) at least one step of separating the stream B to give an organic
phase comprising 1-chloro-2,2-difluoroethane, at least one compound C and
optionally unreacted 1,1,2-trichloroethane and a non-organic phase predominantly
25 comprising HF; (iv) at least one step of separating the 1-chloro-2,2-difluoroethane
from the organic phase obtained in (iii); (v) optional recycling into step (i) of the
organic phase after the separation of step (iv); and (vi) optional recycling into step
(i) of the non-organic phase derived from step (iii).
30 3. The process as claimed in claim 2, characterized in that, in the
separating step (iv), the organic phase comprises 1-chloro-2-fluoroethylene and 1,2-
dichloro-2-fluoroethane.
4. The process as claimed in claim 2 or 3, characterized in that the non-
3 5 organic phase derived from step (iii) is purified such that the HF content is greater
than or equal to 90% by weight before recycling into step (i).
5
10
- 8-
5. The process as claimed in claim 4, characterized in that the
purification comprises at least one distillation, preferably performed at a temperature
of between -23 and 46°C and an absolute pressure of between 0.3 and 3 bar.
6. The process as claimed in any one of claims 2 to 5, characterized in
that the separation step (ii) comprises at least one distillation, preferably performed
at a temperature of between -60 and 89°C and an absolute pressure of between 3 and
11 bar.
7. The process as claimed in any one of claims 2 to 6, characterized in
that the separation step (iii) comprises at least one decantation step, preferably
performed at a temperature of between -20 and 10°C.
15 8. The process as claimed in any one of claims 2 to 7, characterized in
that the separation step (iv) comprises at least one distillation, preferably performed
at a temperature of between 35 and 79°C and an absolute pressure of between 1 and
4 bar.
20 9. The process as claimed in any one of claims 1 to 8, characterized in
that the temperature of the reaction step is between 150 and 400°C, preferably
between 200 and 350°C.
10. The process as claimed in any one of claims I to 9, characterized in
25 that the pressure at which the fluorination reaction is performed is between 1 and 20
bar absolute, preferably between 3 and 15 bar absolute.
11. The process as claimed in any one of claims I to I 0, characterized in
that the amount of hydrofluoric acid used in the reaction is between 5 and 40 mol
30 and preferably between 10 and 30 mol per mole of HCC-140 and/or 1,2-
dichloroethylene.
12. The process as claimed in any one of claims 1 to 11, characterized in
that the oxidizing agent may be chosen from oxygen and chlorine, preferably
3 5 chlorine.
- 9-
13. The process as claimed in claim 12, characterized in that the amount
of oxidizing agent used is between 0.01 mol% to 0.2 mol% per mole ofHCC-140
and/or 1,2-dichloroethylene.
5 14. A composition oftheazeotropic or quasi-azeotropic type comprising
1-chloro-2,2-difluoroethane and trans-1,2-dichloroethylene.
15. The composition as claimed in claim 14, comprising from 80 mol%
to 95 mol% of i;:chloro-2;2-difluoroethane and from 5 mol% to 20 mol% of trans!
0 I ,2-dichloroethylene.
16. The composition as claimed in claim 14 or 15, characterized in that
the boiling point is between 32 and ll9°C at a pressure of between I and I 0 bar abs.