FR3082201A1 - PROCESS FOR PRODUCING 2,3,3,3-TETRAFLUOROPROPENE, REACTOR AND INSTALLATION FOR IMPLEMENTING SAME. - Google Patents

Abstract

The present invention relates to a process for producing 2,3,3,3-tetrafluoropropene in an adiabatic reactor comprising a first fixed bed and a second fixed bed, said process comprising the steps: i) bringing into contact in the gas phase presence or absence of a catalyst, hydrofluoric acid with a stream A comprising at least one chlorine compound selected from the group consisting of 1,1,1,2,3-pentachloropropane, 2,3-dichloro-1,1, 1-trifluoropropane, 2,3,3,3-tetrachloropropene and 1,1,2,3-tetrachloropropene to produce a stream B comprising 2-chloro-3,3,3-trifluoropropene, ii) contacting in the gas phase presence of a catalyst for a stream B comprising 2-chloro-3,3,3-trifluoropropene with hydrofluoric acid to produce a stream D comprising 2,3,3,3-tetrafluoropropene; and iii) recovery at the outlet of the reactor of a stream E comprising 2,3,3,3-tetrafluoropropene, 2-chloro -3,3,3-trifluoropropene, HCI, HF and optionally 1,1,1,2,2 -pentafluoropropane; characterized in that the temperature at the inlet of the first fixed bed is between 300 ° C and 400 ° C and the longitudinal temperature difference between the inlet of the first fixed bed and the outlet of the first fixed bed is less than 20 ° VS ; the temperature at the inlet of the second fixed bed is between 300 ° C and 400 ° C and the longitudinal temperature difference between the inlet of the second fixed bed and the outlet of the second fixed bed is less than 20 ° C.

Description

Process for the production of 2,3,3,3-tetrafluoropropene, reactor and installation for the implementation thereof

Technical field of the invention

The present invention relates to the production of hydrofluoroolefins, in particular the present invention relates to the production of 2,3,3,3-tetrafluoropropene.

Technological background of the invention

Halogenated hydrocarbons, in particular fluorinated hydrocarbons such as hydrofluoroolefins, are compounds which have a useful structure as functional materials, solvents, refrigerants, blowing agents and monomers for functional polymers or starting materials for such monomers. Hydrofluoroolefins such as 2,3,3,3-tetrafluoropropene (HFO-1234yf) attract attention because they offer promising behavior as refrigerants with low global warming potential.

The processes for producing fluoroolefins are usually carried out in the presence of a starting material such as an alkane containing chlorine or an alkene containing chlorine, and in the presence of a fluorinating agent such as hydrogen fluoride. These processes can be carried out in the gas phase or in the liquid phase, with or without the catalyst. For example, US 2009/0240090 discloses a gas phase process for the preparation of 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) from 1,1,1,2,3pentachloropropane (HCC-240db) . The HCFO-1233xf thus produced is converted into 2-chloro-

1.1.1.2- tetrafluoropropane (HCFC-244bb) in the liquid phase then the latter is converted into

2.3.3.3- tetrafluoropropene.

Also known from WO 2013/088195 is a process for the preparation of 2,3,3,3tetrafluoropropene from 1,1,1,2,3-pentachloropropane and / or 1,1,2,2,3pentachloropropane, comprising stages: (a) catalytic reaction of 1,1,1,2,3pentachloropropane and / or 1,1,2,2,3-pentachloropropane with HF to a reaction mixture comprising HCl, 2-chloro-3,3,3- trifluoropropene, 2,3,3,3-tetrafluoropropene, unreacted HF and optionally 1,1,1,2,2-pentafluoropropane; (b) separation of the reaction mixture into a first stream comprising HCl and 2,3,3,3-tetrafluoropropene and a second stream comprising HF, 2-chloro-3,3,3-trifluoropropene and optionally 1,1,1,2 , 2pentafluoropropane; (c) catalytic reaction of said second stream into a reaction mixture comprising 2,3,3,3-tetrafluoropropene, HCl, 2-chloro-3,3,3-trifluoropropene, unreacted HF and optionally 1,1,1, 2,2-pentafluoropropane and (d) feeding the reaction mixture obtained in step c) directly to step a) without separation.

In the processes for producing 2,3,3,3-tetrafluoropropene, the control and control of the reaction temperature is an important parameter which makes it possible to achieve the reaction kinetics, the conversions and the selectivities. This is also particularly recommended to avoid thermal decompositions of thermally sensitive compounds which can impact the activity of the catalyst by the formation of coke and thus considerably reduce the lifetime of the catalyst.

It is known from WO2008 / 054781 that a temperature (300-350 ° C) promotes the formation of 1234yf, 245cb, 1233xf, while a higher temperature (350-450 ° C) promotes the formation of the 1234ze, 245fa, 1233zd isomers.

It is therefore important to control and control the temperature of the gases entering the reactors but also to control and control at any point of the catalytic mass, if there is one.

A multitubular reactor is by definition the ideal isothermal reactor to be able to control the reaction temperature and obtain a reaction temperature as homogeneous as possible since the catalyst is distributed in tubes and a fluid can circulate in the shell around the tubes to either remove reaction heat in the event of an exothermic reaction, or provide heat in the event of an endothermic reaction. On the other hand, when large quantities of catalysts have to be used, the production of a multitubular reactor may prove impossible since it would require too many tubes and a homogeneous distribution of the gases in each of the tubes is therefore very difficult. to achieve. In addition, the maintenance of large multitubular reactors is much more delicate and expensive; in particular, the catalyst change operations require a long immobilization of the reactor both to drain the used catalyst and to fill each tube extremely homogeneously with new catalyst. This negative aspect will be reinforced when the lifetime of the catalyst is short.

Therefore, the use of an adiabatic fixed bed reactor is preferred. However, this type of reactor does not exhibit heat exchange with an external environment by definition. Indeed, the adiabatic reactor is characterized by an inhomogeneous temperature at any point of the fixed bed and thus, by a temperature gradient both radial and longitudinal, due to the reaction heats and heat losses at the external walls of the reactor.

Document US 2016/0347692 describes the implementation of a radical production process in homogeneous gas phase of chlorinated or fluorinated propene in an adiabatic flow reactor controlling the turbulence of the flows entering the reactor.

There is however a need to improve the processes for producing 2,3,3,3tetrafluoropropene in adiabatic reactors.

Summary of the invention

According to a first aspect, the present invention relates to a method for producing

2.3.3.3- tetrafluoropropene in an adiabatic reactor comprising a first fixed bed and a second fixed bed, said process comprising the steps:

i) bringing into contact in the gas phase, in the presence or not of a catalyst, of hydrofluoric acid with a stream A comprising at least one chlorine compound selected from the group consisting of 1,1,1,2,3-pentachloropropane, 2 , 3-dichloro-l, l, l-trifluoropropane,

2.3.3.3- tetrachloropropene and 1,1,2,3-tetrachloropropene to produce a stream B comprising 2-chloro-3,3,3-trifluoropropene, ii) contacting in the gas phase in the presence of a catalyst of a stream C comprising 2-chloro-3,3,3-trifluoropropene with hydrofluoric acid to produce a stream D comprising 2,3,3,3-tetrafluoropropene; and iii) recovery at the outlet of the reactor of a stream E comprising 2,3,3,3tetrafluoropropene, 2-chloro-3,3,3-trifluoropropene, HCl, HF and optionally 1,1,1,2,2pentafluoropropane;

characterized in that the temperature at the inlet of the first fixed bed is between 300 ° C and 400 ° C and the longitudinal temperature difference between the inlet of the first fixed bed and the outlet of the first fixed bed is less than 20 ° VS ;

the temperature at the inlet of the second fixed bed is between 300 ° C and 400 ° C and the longitudinal temperature difference between the inlet of the second fixed bed and the outlet of the second fixed bed is less than 20 ° C.

The value of the longitudinal temperature difference is considered in absolute value.

According to a preferred embodiment, said first fixed bed is arranged above said second fixed bed; and the temperature at the outlet of the first fixed bed is greater than the temperature or equal to the inlet of the second fixed bed.

According to a preferred embodiment, step i) is implemented in the first fixed bed, step ii) is implemented in the second fixed bed and the current C is introduced into the reactor between the first and the second fixed bed.

According to a preferred embodiment, the temperature at the inlet of the first fixed bed is between 340 ° C and 380 ° C and the temperature at the inlet of the second fixed bed is between 330 ° C and 360 ° C.

According to a preferred embodiment, step i) is implemented in the second fixed bed, step ii) is implemented in the first fixed bed and the current A is introduced into the reactor between the first and the second fixed bed.

According to a preferred embodiment, the temperature at the inlet of the second fixed bed is between 340 ° C and 380 ° C and the temperature at the inlet of the first fixed bed is between 330 ° C and 360 ° C.

According to a preferred embodiment, the HF / 2-chloro-3,3,3trifluoropropene molar ratio in step ii) or the molar ratio between HF and said chlorinated compound in step i) or both is adjusted so to maintain the longitudinal temperature difference between the inlet and the outlet of the fixed bed considered less than 20 ° C.

According to a preferred embodiment, the HF / 2-chloro-3,3,3trifluoropropene molar ratio, in step ii), is greater than or equal to 5, advantageously greater than or equal to 10, preferably greater than or equal to 12 .

According to a preferred embodiment, the HF / chlorine compound molar ratio, in step i), is greater than or equal to 5, advantageously greater than or equal to 10, preferably greater than or equal to 12.

According to a preferred embodiment, said reactor comprises side walls, these comprising an inner layer, an intermediate layer disposed on said inner layer and an insulating layer disposed on said intermediate layer; and the difference in radial temperature between a point situated in the center of the fixed bed considered and a point situated in the radial plane at the level of the inner layer of the side wall of the reactor is less than 10 ° C. The value of the radial temperature difference is considered as an absolute value.

According to a preferred embodiment, said reactor comprises side walls, these comprising an inner layer, an intermediate layer disposed on said inner layer and an insulating layer disposed on said intermediate layer; said insulating layer being made of an M2 heat-insulating material whose thickness varies between 1 mm and 500 mm.

According to a preferred embodiment, the M2 heat-insulating material is selected from the group consisting of rock wool, glass wool, silicate fibers, calcium magnesium silicates, calcium silicates, microporous insulators, cellular glass , expanded perlite, exfoliated vermiculite.

According to a second aspect, the present invention provides an adiabatic reactor comprising a bottom, a cover and side walls joining between the bottom and the cover, a first fixed bed, a second fixed bed and at least one rod supporting one or more sensors. (s) temperature; said bottom, said cover and said side walls each comprise at least one inner layer, an intermediate layer disposed on said inner layer and an insulating layer disposed around said intermediate layer; characterized in that:

- Said inner layer is made of an Ml material comprising a mass content of nickel of at least 30%;

- Said intermediate layer is made of a material ΜΓ comprising at least 70% by weight of iron;

- said insulating layer is made of an M2 heat-insulating material selected from the group consisting of rock wool, glass wool, silicate fibers, calcium magnesium silicates, calcium silicates, microporous insulators, cellular glass, expanded perlite, exfoliated vermiculite;

- the first fixed bed is arranged above the second fixed bed,

- The length of said at least one rod supporting one or more temperature sensor (s) is at least equal to the distance between the inlet of the first fixed bed and the outlet of the second fixed bed; and

- Said at least one rod comprises at least one temperature sensor arranged in said first fixed bed and at least one temperature sensor arranged in said second fixed bed.

According to a third aspect, the present invention provides an installation for manufacturing 2,3,3,3-tetrafluoropropene, comprising:

- an adiabatic reactor according to the present invention,

- A first reaction flow supply device for said reactor connected to the cover of said reactor;

- a second reaction flow supply device for said reactor connected to the side wall of said reactor and disposed between the first fixed bed and the second fixed bed;

- a device for collecting and purifying the outlet flow from said reactor.

According to a preferred embodiment, the reaction flow supply device connected to the cover of said reactor comprises a line for supplying hydrofluoric acid, a line for supplying current A as defined in the present invention, and a device for mixing hydrofluoric acid and stream A, and the reaction flow supply device connected to the side wall of said reactor of said reactor comprises a line for supplying hydrofluoric acid and a line for supplying current C as defined in the present invention.

According to another preferred embodiment, the reaction flow supply device connected to the cover of said reactor comprises a supply line for hydrofluoric acid and a supply line for stream C as defined in the present invention, and the reaction flow supply device connected to the side wall of said reactor comprises a line for supplying hydrofluoric acid, a line for supplying current A as defined in the present invention, and a device for mixing the hydrofluoric acid and current A.

Brief description of the figures

FIG. 1 schematically represents a reactor according to a particular embodiment of the present invention.

FIG. 2 schematically represents a view in longitudinal section of a reactor according to a particular embodiment of the present invention.

FIG. 3 schematically represents a cross-sectional view of a reactor according to a particular embodiment of the present invention.

Figure 4 schematically shows a sectional view of the side walls of a reactor according to a particular embodiment of the present invention.

FIG. 5 schematically represents an installation for manufacturing 2,3,3,3tetrafluoropropene according to a particular embodiment of the present invention.

Detailed description of the invention

The present invention relates to a method for producing 2,3,3,3tetrafluoropropene (HFO-1234yf). More particularly, the invention relates to a production process implemented in an adiabatic reactor comprising a first fixed bed and a second fixed bed.

Preferably, said process for producing 2,3,3,3-tetrafluoropropene comprises the steps:

i) bringing into contact in the gas phase, in the presence or not of a catalyst, of hydrofluoric acid with a stream A comprising at least one chlorine compound selected from the group consisting of 1,1,1,2,3-pentachloropropane, 2 , 3-dichloro-l, l, l-trifluoropropane,

2,3,3,3-tetrachloropropene and 1,1,2,3-tetrachloropropene to produce a stream B comprising 2-chloro-3,3,3-trifluoropropene, ii) contacting in the gas phase in the presence of a catalyst of a stream C comprising 2-chloro-3,3,3-trifluoropropene with hydrofluoric acid to produce a stream D comprising 2,3,3,3-tetrafluoropropene, iii) recovery at the outlet of the reactor of a stream E comprising 2,3,3,3tetrafluoropropene, 2-chloro-3,3,3-trifluoropropene, HCl, HF and optionally 1,1,1,2,2pentafluoropropane.

Preferably, the temperature at the inlet of the first fixed bed is between 300 ° C and 400 ° C and the longitudinal temperature difference between the inlet of the first fixed bed and the outlet of the first fixed bed is less than 20 ° C .

Preferably, the temperature at the inlet of the second fixed bed is between 300 ° C and 400 ° C and the longitudinal temperature difference between the inlet of the second fixed bed and the outlet of the second fixed bed is less than 20 ° C .

Preferably, said first fixed bed is arranged above said second fixed bed; and the temperature at the outlet of the first fixed bed is greater than or equal to the temperature at the inlet of the second fixed bed.

As mentioned above, in an adiabatic reactor, the temperature within the reactor, and in particular within the fixed bed, varies longitudinally, i.e. the temperature varies between the inlet of the reactor and the outlet of the reactor, in particular between the inlet of the fixed bed and the outlet of the fixed bed. FIG. 2 represents a schematic view in longitudinal section of a reactor 1 according to a particular embodiment of the present invention and comprising a fixed bed 5. The longitudinal temperature difference ATa is defined by the temperature difference between the inlet of the fixed bed 9 considered and the output of the fixed bed 10 considered.

According to a first embodiment, step i) is implemented in the first fixed bed, step ii) is implemented in the second fixed bed and the current C is introduced into the reactor between the first and the second fixed bed. Thus, the temperature at the inlet of the first fixed bed of said reactor is between 330 ° C and 400 ° C, preferably between 330 ° C and 390 ° C, in particular between 340 ° C and 380 ° C. The temperature at the inlet of the second fixed bed of said reactor is between 320 ° C and 400 ° C, preferably between 320 ° C and 375 ° C, more preferably between 320 ° C and 360 ° C, in particular between 330 ° C and 360 ° C. A temperature above 400 ° C can make the catalyst irreversibly inactive while a temperature below 300 ° C prevents the fluorination reaction from being carried out. In this embodiment, preferably, the longitudinal temperature difference between the inlet of the first fixed bed of said reactor and the outlet of the first fixed bed of said reactor is less than 20 ° C, advantageously less than 19 ° C, preferably less at 18 ° C, more preferably less than 17 ° C, in particular less than 16 ° C, more particularly less than 15 ° C, preferably less than 14 ° C, advantageously less than 13 ° C, so preferably preferred less than 12 ° C, more preferably preferred less than 11 ° C, particularly preferred less than 10 ° C. Preferably, the longitudinal temperature difference between the inlet of the second fixed bed of said reactor and the outlet of the second fixed bed of said reactor is less than 20 ° C, advantageously less than 19 ° C, preferably less than 18 ° C, more preferably less than 17 ° C, in particular less than 16 ° C, more particularly less than 15 ° C, preferably less than 14 ° C, advantageously less than 13 ° C, preferably less than 12 ° C, more preferably less than 11 ° C, particularly preferably less than 10 ° C.

According to a second embodiment, step i) is implemented in the second fixed bed, step ii) is implemented in the first fixed bed and the current A is introduced into the reactor between the first and the second fixed bed. Thus, the temperature at the inlet of the first fixed bed of said reactor is between 320 ° C and 400 ° C, preferably between 320 ° C and 375 ° C, more preferably between 320 ° C and 360 ° C, in particular between 330 ° C and 360 ° C. The temperature at the inlet of the second fixed bed of said reactor is between 330 ° C and 400 ° C, preferably between 330 ° C and 390 ° C, in particular between 340 ° C and 380 ° C. A temperature above 400 ° C can make the catalyst irreversibly inactive while a temperature below 300 ° C prevents the fluorination reaction from being carried out. In this embodiment, preferably, the longitudinal temperature difference between the inlet of the first fixed bed of said reactor and the outlet of the first fixed bed of said reactor is less than 20 ° C, advantageously less than 19 ° C, preferably less at 18 ° C, more preferably less than 17 ° C, in particular less than 16 ° C, more particularly less than 15 ° C, preferably less than 14 ° C, advantageously less than 13 ° C, so preferably preferred less than 12 ° C, more preferably preferred less than 11 ° C, particularly preferred less than 10 ° C. Preferably, the longitudinal temperature difference between the inlet of the second fixed bed of said reactor and the outlet of the second fixed bed of said reactor is less than 20 ° C, advantageously less than 19 ° C, preferably less than 18 ° C, more preferably less than 17 ° C, in particular less than 16 ° C, more particularly less than 15 ° C, preferably less than 14 ° C, advantageously less than 13 ° C, preferably less than 12 ° C, more preferably less than 11 ° C, particularly preferably less than 10 ° C.

According to a preferred embodiment, step i) and step ii) are carried out in the presence of a catalyst, preferably a chromium-based catalyst. Preferably, the chromium-based catalyst can be a chromium oxide (for example CrCh, Crûs or CrjOa), a chromium oxyfluoride or a chromium fluoride (for example CrFa) or a mixture of these. The chromium oxyfluoride may contain a fluorine content of between 1 and 60% by weight based on the total weight of the chromium oxyfluoride, advantageously between 5 and 55% by weight, preferably between 10 and 52% by weight, more preferably between 15 and 52% by weight, in particular between 20 and 50% by weight, more particularly between 25 and 45% by weight, preferably between 30 and 45% by weight, more preferably between 35 and 45% by weight of fluorine based on the total weight of chromium oxyfluoride. The catalyst can also comprise a co-catalyst chosen from the group consisting of Ni, Co, Zn, Mg, Mn, Fe, Zn, Ti, V, Zr, Mo, Ge, Sn, Pb, Sb; preferably Ni, Co, Zn, Mg, Mn; in particular Ni, Co, Zn. The content by weight of the cocatalyst is between 1 and 10% by weight based on the total weight of the catalyst. The catalyst may or may not be supported. A support such as alumina, for example in its alpha form, activated alumina, aluminum halides (AIF3 for example), aluminum oxyhalides, activated carbon, magnesium fluoride or graphite can be used.

Preferably, the catalyst can have a specific surface between 1 and 100 m ² / g, preferably between 5 and 80 m ² / g, more preferably between 5 and 70 m ² / g, ideally between 5 and 50 m ² / g, in particular between 10 and 50 m ² / g, more particularly between 15 and 45 m ² / g.

According to a preferred embodiment, step i) and step ii) are carried out at atmospheric pressure or at a pressure greater than this, advantageously at a pressure greater than 1.5 bara, preferably at a pressure greater than 2.0 bara, in particular a pressure greater than 2.5 bara, more particularly a pressure greater than 3.0 bara. Preferably, step i) and step ii) are implemented at a pressure between atmospheric pressure and 20 bara, preferably between 2 and 18 bara, more preferably between 3 and 15 bara. Preferably, step i) and step ii) are implemented with a contact time between 1 and 100 s, preferably between 2 and 75 s, in particular between 3 and 50 s. You can add an oxidant, such as oxygen or chlorine. The molar ratio of the oxidant to the hydrocarbon compound can be between 0.005 and 2, preferably between 0.01 and 1.5. The oxidant can be pure oxygen, air or a mixture of oxygen and nitrogen.

Preferably, in step ii), the HF / 2-chloro-3,3,3-trifluoropropene molar ratio is greater than or equal to 5, advantageously greater than or equal to 10, preferably greater than or equal to 12. Advantageously, the HF / 2-chloro-3,3,3-trifluoropropene molar ratio is between 12: 1 and 150: 1, preferably between 12: 1 and 125: 1, more preferably between 12: 1 and 100: 1.

Preferably, in step i), the HF / said molar ratio of said at least one chlorinated compound is greater than or equal to 5, advantageously greater than or equal to 10, preferably greater than or equal to 12. Advantageously the HF / said molar ratio at least one chlorinated compound is between 12: 1 and 150: 1, preferably between 12: 1 and 125: 1, more preferably between 12: 1 and 100: 1.

As mentioned above, in an adiabatic reactor, the temperature within the reactor, and in particular within the fixed bed, varies radially, i.e. the temperature varies between the center of the reactor and the side walls of the reactor located in the same plane, in particular between the center of the fixed bed and the side wall of the reactor located in the same plane.

The control of the radial temperature in the fixed bed can be carried out by insulating the side walls of said reactor with an insulating material of a defined thickness. Thus, said side walls each comprise at least one inner layer and an insulating layer disposed around said inner layer.

FIG. 3 represents a transverse view along the section plane (a, a ') of a reactor 1 according to an embodiment of the present invention and comprising a fixed bed 5. The side walls 3 of said reactor comprise an inner layer 21 , an intermediate layer 22 disposed on said inner layer 21 and an insulating layer 23 disposed on said intermediate layer 22 (Figure 4). The difference in radial temperature ATb is defined by the difference between a point located in the center of the fixed bed 5 of one of said first or second reactors and a point 12 located in the radial plane at the level of the inner layer 21 of the side wall 3 of said reactor (Figure 3).

Thus, the difference in radial temperature between a point located in the center of the fixed bed considered and a point situated in the radial plane at the level of the inner layer of the side wall of said reactor is less than 10 ° C, advantageously less than 9 ° C , preferably less than 8 ° C, more preferably less than 7 ° C, in particular less than 6 ° C, more particularly less than 5 ° C.

Thus, the difference in radial temperature between a point located in the center of the first fixed bed of the reactor and a point located in the radial plane at the level of the inner layer of the side wall of the reactor is less than 10 ° C., advantageously less than 9 ° C, preferably less than 8 ° C, more preferably less than 7 ° C, in particular less than 6 ° C, more particularly less than 5 ° C.

In addition, the difference in radial temperature between a point located in the center of the second fixed bed of the reactor and a point situated in the radial plane at the level of the inner layer of the side wall of the reactor is less than 10 ° C., advantageously less than 9 ° C, preferably less than 8 ° C, more preferably less than 7 ° C, in particular less than 6 ° C, more particularly less than 5 ° C.

According to a preferred embodiment, said inner layer has a thickness of between 0.01 and 20 mm. Preferably, said inner layer may have a thickness of between 0.05 and 15 mm, preferably between 0.1 and 10 mm, more preferably between 0.1 and 5 mm.

Said inner layer can be made of an Ml material comprising a mass content of nickel of at least 30%. Advantageously, the material M1 comprises at least 40% by weight of nickel based on the total weight of the material Ml. Preferably, the material M1 comprises at least 45% by weight of nickel, more preferably at least 50% by weight of nickel, in particular at least 55% by weight of nickel, more particularly at least 60% by weight of nickel, preferably at least 65% by weight of nickel, more preferably at least 70% by weight of nickel based on the total weight of the material Ml. The material M1 can also comprise chromium in a content of less than 35% by weight based on the total weight of the material Ml, advantageously less than 30% by weight, preferably less than 20% by weight, more preferably less than 15% by weight. weight, in particular less than 10% by weight, more particularly less than 5% by weight based on the total weight of the material Ml. The material M1 can also comprise molybdenum in a content of less than 35% by weight based on the total weight of the material Ml, advantageously less than 30% by weight, preferably less than 20% by weight, more preferably less than

15% by weight, in particular less than 10% by weight, more particularly less than 5% by weight based on the total weight of the material Ml. Preferably, the material M1 comprises at least 40% by weight of nickel based on the total weight of the material Ml, preferably at least 45% by weight of nickel, more preferably at least 50% by weight of nickel, in particular at least 55% by weight of nickel, more particularly at least 60% by weight of nickel, preferably at least 65% by weight of nickel, more preferably at least 70% by weight of nickel based on the total weight of the material Ml ; and less than 35% by weight of chromium, advantageously less than 30% by weight, preferably less than 20% by weight, more preferably less than 15% by weight, in particular less than 10% by weight, more particularly less than 5 % by weight of chromium based on the total weight of the material Ml; and less than 35% by weight of molybdenum, advantageously less than 30% by weight, preferably less than 20% by weight, more preferably less than 15% by weight, in particular less than 10% by weight, more particularly less than 5 % by weight of molybdenum, based on the total weight of the material Ml. The material M1 can also comprise cobalt in a content of less than 10% by weight based on the total weight of the material Ml, advantageously less than 8% by weight, preferably less than 6% by weight, more preferably less than 4% by weight. weight, in particular less than 3% by weight, more particularly less than 2% by weight based on the total weight of the material Ml. The material Ml can also comprise tungsten in a content of less than 10% by weight based on the total weight of the material Ml, advantageously less than 9% by weight, preferably less than 8% by weight, more preferably less than 7% by weight. weight, in particular less than 6% by weight, more particularly less than 5% by weight based on the total weight of the material Ml. The material M1 can also comprise iron in a content of less than 25% by weight based on the total weight of the material Ml, advantageously less than 20% by weight, preferably less than 15% by weight, more preferably less than 10% by weight. weight, in particular less than 7% by weight, more particularly less than 5% by weight based on the total weight of the material Ml. The material M1 can also comprise manganese in a content of less than 5% by weight based on the total weight of the alloy, advantageously less than 4% by weight, preferably less than 3% by weight, more preferably less than 2% by weight, in particular less than 1% by weight, more particularly less than 0.5% by weight based on the total weight of the material Ml. The material M1 can also comprise copper in a content of less than 50% by weight, advantageously less than 45% by weight, preferably less than 40% by weight, more preferably less than 35% by weight, in particular less than 30%. by weight, more particularly less than 25% by weight of copper based on the total weight of the material Ml.

According to a preferred embodiment, said intermediate layer has a thickness of between 0.1 and 50 mm. Preferably, said intermediate layer may have a thickness of between 0.5 and 40 mm, preferably between 1 and 30 mm, more preferably between 1 and 25 mm. According to a preferred embodiment, said intermediate layer 22 is disposed between said inner layer 21, in contact with the reagents, and said insulating layer 23 (Figure 4). Said intermediate layer 22 can be made of a material ΜΓ. According to a preferred embodiment, the material ΜΓ comprises at least 70% by weight of iron, advantageously at least 75% by weight, preferably at least 80% by weight, more preferably at least 85% by weight, in particular at least 90% by weight, more particularly at least 95% by weight of iron based on the total weight of the material ΜΓ. The material ΜΓ can also comprise less than 2% by weight of carbon, advantageously less than 1.5% by weight, preferably less than 1% by weight, more preferably less than 0.75% by weight, in particular less than 0 , 5% by weight, more particularly less than 0.2% by weight, preferably less than 0.1% by weight based on the total weight of the material ΜΓ. More particularly, the material ΜΓ can comprise between 0.01 and 0.2% by weight of carbon based on the total weight of the material ΜΓ. The material ΜΓ can also comprise less than 2% by weight of molybdenum, advantageously less than 1.5% by weight, preferably less than 1.25% by weight, more preferably less than 1% by weight of molybdenum based on the weight total material ΜΓ. More particularly, the material ΜΓ can comprise between 0.1 and 1% by weight of molybdenum based on the total weight of the material ΜΓ. The material ΜΓ can also comprise less than 5% by weight of chromium, advantageously less than 4% by weight, preferably less than 3% by weight, more preferably less than 2% by weight, in particular less than 1% by weight of chromium based on the total weight of the material ΜΓ. More particularly, the material ΜΓ can comprise between 0.5 and 2% by weight of chromium based on the total weight of the material ΜΓ. The material ΜΓ can also comprise less than 2% by weight of silicon, advantageously less than 1.5% by weight, preferably less than 1.25% by weight, more preferably less than 1% by weight of silicon based on the weight total material ΜΓ. More particularly, the material ΜΓ can comprise between 0.1 and 1.5% by weight of silicon based on the total weight of the material ΜΓ. The material ΜΓ can also comprise less than 2% by weight of manganese, advantageously less than 1.5% by weight, preferably less than 1.25% by weight, more preferably less than 1% by weight of manganese based on the weight total material ΜΓ. More particularly, the material ΜΓ can comprise between 0.1 and 1% by weight of manganese based on the total weight of the material M1 '.

Preferably, said insulating layer is made of an M2 heat-insulating material. Said M2 heat-insulating material is selected from the group consisting of rock wool, glass wool, silicate fibers, calcium-magnesium silicates, calcium silicates, microporous insulators, cellular glass, expanded perlite, vermiculite exfoliated. Silicate fibers include, for example, aluminosilicate fibers.

In particular, the side walls of said first reactor comprise a layer made of an M2 heat-insulating material whose thickness varies between 1 mm and 500 mm, preferably between 5 mm and 400 mm.

In particular, the side walls of said second reactor comprise a layer made of an M2 heat-insulating material whose thickness varies between 1 mm and 500 mm, preferably between 5 mm and 400 mm.

According to a preferred embodiment, hydrofluoric acid and said at least one chlorinated compound are brought into contact before entering them into said reactor. The resulting mixture is mixture F. Preferably, said at least one chlorinated compound is in the liquid state before its contact with hydrofluoric acid. This is vaporized by mixing with hydrofluoric acid. The resulting mixture F is then in gaseous form. In particular, the mixing between hydrofluoric acid and said at least one chlorinated compound is carried out in a static mixer. Preferably, said at least one chlorinated compound is introduced into the static mixer via one or more spray nozzles. Said at least one chlorinated compound is thus sprayed in the form of droplets before being vaporized by mixing with hydrofluoric acid; thus forming a mixture F in gaseous form. Spraying said at least one chlorinated compound in the form of fine droplets makes it possible to ensure a more efficient vaporization of the latter. For example, the average diameter of the droplets thus produced can be less than 500 μm. Said mixture F can optionally be heated or cooled before its introduction into the reactor. This step can be carried out via a heat exchanger to control the temperature at the inlet of the reactor.

As mentioned above, said stream E recovered at the outlet of the reactor comprises 2,3,3,3-tetrafluoropropene, HF, HCl, unreacted 2-chloro-3,3,3-trifluoropropene and optionally 1, 1,1,2,2-pentafluoropropane. Preferably, the stream E is purified, preferably by distillation, to form a stream G comprising 2,3,3,3-tetrafluoropropene,

HCl and optionally 1,1,1,2,2-pentafluoropropane, and an H stream comprising HF and 2-chloro-3,3,3-trifluoropropene.

Preferably, said stream E is distilled under conditions sufficient to form said stream G comprising 2,3,3,3-tetrafluoropropene, HCl and optionally 1,1,1,2,2pentafluoropropane, and said stream H comprising HF and 2- chloro-3,3,3-trifluoropropene. In particular, the distillation can be carried out at a pressure of 2 to 6 bara, more particularly at a pressure of 3 to 5 bara. In particular, the temperature at the top of the distillation column is from -35 ° C to 10 ° C, preferably from -20 ° C to 0 ° C.

According to a preferred embodiment, said stream H is recycled upstream of the first fixed bed or upstream of the second fixed bed or upstream of the two catalytic beds. Said stream H can optionally be purified, in particular by distillation, before being recycled.

According to a preferred embodiment, said stream E recovered in step iii) is cooled before the purification mentioned above. In particular, said stream E recovered in step iii) is cooled to a temperature below 100 ° C., then distilled to form said stream G comprising 2,3,3,3-tetrafluoropropene, HCl and optionally 1,1,1 , 2,2pentafluoropropane, and said stream H comprising HF and 2-chloro-3,3,3-trifluoropropene; the temperature at the top of the distillation column is from -35 ° C to 10 ° C and the distillation is carried out at a pressure of 2 to 6 bara; said stream H obtained at the bottom of the distillation column is recycled in step i) or in step ii), preferably in step ii). Said stream E can be cooled, before distillation, to a temperature below 95 ° C, advantageously below 90 ° C, preferably below 85 ° C, more preferably below 80 ° C, in particular below 70 ° C, more particularly less than 60 ° C, preferably less than 55 ° C, advantageously less than 50 ° C, preferably less than 40 ° C, more preferably less than 30 ° C, so particularly preferred less than 25 ° C, more particularly preferred less than 20 ° C. The cooling of the product stream obtained at such temperatures facilitates subsequent distillation. The cooling of said current E can be carried out by means of one or a plurality of heat exchangers. The cooling of said current E can be carried out by passing it through one, two, three, four, five, six, seven, eight, nine or ten heat exchangers, preferably the number of heat exchangers is between 2 and 8, in particular between 3 and 7.

Preferably, the method according to the present invention is implemented continuously.

Preferably, the process is carried out continuously and in the gas phase.

Preferably, said recycled stream H, upstream of the first fixed bed or upstream of the second fixed bed or upstream of the two catalytic beds, has an electrical conductivity of less than 15 mS / cm, advantageously less than 14 mS / cm, preferably less at 13 mS / cm, more preferably less than 12 mS / cm, in particular less than 11 mS / cm, more particularly less than 10 mS / cm, preferably less than 9 mS / cm, advantageously less than 8 mS / cm, preferably preferably less than 7 mS / cm, more preferably preferred less than 6 mS / cm, particularly preferably less than 5 mS / cm. The electrical conductivity of said current H is measured prior to its introduction into the reactor. Preferably, the electrical conductivity is measured when the latter is in liquid form. Preferably, step i) and / or step ii) is carried out in the presence of hydrofluoric acid having an electrical conductivity of less than 10 mS / cm, preferably less than 5 mS / cm.

According to a second aspect of the present invention, an adiabatic reactor 1 is provided. Preferably, said reactor 1 comprises a bottom 4, a cover 2 and side walls 3 joining between the bottom 4 and the cover 2, a first fixed bed 5a, a second fixed bed 5b and at least one rod 6 supporting one or more several temperature sensors 7a, 7b, 7b '(Figure 1). Preferably, said bottom 4, said cover 2 and said side walls 3 each comprise at least one inner layer 21, an intermediate layer 22 disposed on said inner layer and an insulating layer 23 disposed around said intermediate layer. Said inner 21, intermediate 22 and insulating 23 layers are made respectively of a material Ml, ΜΓ and M2 as described above. According to a preferred embodiment, said insulating layer 23 can be covered by a base layer 24. Thus, said insulating layer 23 is disposed between said intermediate layer 22 and said base layer 24 (Figure 4). Said base layer 24 can be made of an M3 material. Said M3 material can be a metallic coating made with sheets of aluminum, stainless steel or galvanized steel. Preferably, said base layer has a thickness of between 0.2 mm and 2 mm. Said inner layer 21, said intermediate layer 22, said insulating layer 23 and said base layer 22 can be placed one on the other according to techniques well known to those skilled in the art.

Preferably, the first fixed bed is arranged above the second fixed bed. The reaction flow flows from the reactor cover to the bottom of the reactor. The reactor cover is equipped with at least one inlet capable of allowing the introduction of the reaction flow into the reactor. The bottom of the reactor is equipped with at least one outlet capable of allowing the evacuation of the reaction flow from the reactor.

Preferably, the length of said at least one rod 6 is at least equal to the distance between the inlet of the first fixed bed 5a and the outlet of the second fixed bed 5b. In particular, said at least one rod 6 comprises at least one sensor or at least two sensors or at least 3 temperature sensors, advantageously at least 5 temperature sensors, preferably at least 7 temperature sensors, in particular at least 10 sensors temperature, preferably at least 12 temperature sensors, preferably at least 15 temperature sensors. Preferably, at least one of said one or more temperature sensors, supported by said at least one rod, is arranged in said first fixed bed 5a. In particular, at least two or three or four or five or six or seven temperature sensors, supported by said at least one rod, are arranged in said first fixed bed 5a. Preferably, at least one of said one or more temperature sensors, supported by said at least one rod, is arranged in said second fixed bed 5b. In particular, at least two or three or four or five or six or seven temperature sensors, supported by said at least one rod, are arranged in said second fixed bed 5b. Preferably, each rod 6 can comprise either an identical number or a different number of temperature sensors. In particular, each rod can include a temperature sensor in the sky and / or in the bottom of the reactor and / or between the catalytic beds (Figure 1, Reference 7b). Likewise, the temperature sensors 7a, 7b can be distributed equidistantly or in a more targeted manner according to the needs for controlling the temperature profile in the first or second fixed bed. Preferably, said reactor can comprise at least two canes 6, more preferably at least three canes 6, in particular at least four canes 6. In particular, said reactor can comprise between 1 and 20 canes 6, advantageously between 2 and 15 canes 6 , preferably between 3 and 10 rods 6. Preferably, at least one of said one or more temperature sensors, supported by said at least one rod, is disposed between the first and the second fixed bed (Figure 1, Reference 7b ') .

Preferably, the reactor 1 is supplied with reaction flow 14,14 'by at least two supply lines 13,13' (Figure 1). At least one of the two supply lines (Figure 1, Reference 13 ') is connected to the side wall 3 of said reactor 1 and disposed between the first fixed bed 5a and the second fixed bed 5b. The reactor also includes effluent or outlet lines 15 making it possible to evacuate the reaction flow 16 from the reactor (FIG. 1). Preferably, the reactor inlet or outlet lines are made of material capable of also resisting corrosion, for example made of Ml material covered with a layer of M2 material and with a base layer made of a material M3. The supply lines can be tubular. Alternatively, the supply or exit lines can comprise an inner layer, preferably made of a material M1 as described above, an insulating layer, preferably made of a material M2 as described above, and a base layer, preferably made of an M3 material as described above. The reactor also includes one or more dephlegmator (s), one or more dip tube (s), one or more raw material introduction device (s), one or more support and retaining grid (s) of the catalyst. Said one or more dephlegmator (s) and / or said one or more dip tube (s) and / or said one or more device (s) for introducing the raw materials and / or said one or more grid (s) ) supporting and retaining the catalyst may comprise an inner layer, preferably made of a material M1 as described above.

Preferably, said first or second fixed bed 5a, 5b comprises a catalyst or an inert solid or both. The inert solid can be corundum, silicon carbide, quartz balls or rings, a metal lining with a metal M1 as defined in the present application or nickel balls. Preferably, when the fixed bed 5a or 5b comprises a catalyst, the inert solid is placed respectively in the upper part 17 and the lower part 18 of the fixed bed 5a or 5b, said catalyst 19c being between the layers of inert solid 19a and 19b, in the central part 20 of the fixed bed 5a or 5b. In an alternative embodiment, when the fixed bed 5a or 5b comprises a catalyst, the inert solid is placed in the upper part 17 or in the lower part 18 of the fixed bed 5a or 5b. In an alternative embodiment, when the fixed bed 5a or 5b comprises a catalyst, no layer of inert solid is placed in the fixed bed 5a or 5b. In an alternative embodiment, in which the fixed bed 5a or 5b does not contain catalyst, the lower part 18, the central part 20 and the upper part 17 of the fixed bed 5a or 5b can contain only inert solid. This alternative embodiment can be implemented when, for example, step i) of the process according to the present invention is carried out in the absence of catalyst. In this case, corundum improves the distribution of gases inside the reactor. Preferably, the inert solid is corundum or nickel beads.

Preferably, the fixed bed 5a or 5b contains a layer of catalyst 19c in its central part 20. In a preferred embodiment, the catalyst is distributed homogeneously in the fixed bed. The homogeneous distribution of the catalyst in the fixed bed makes it possible to minimize disturbances in the flow of gases and to avoid hot spots within the catalyst layer. The presence of hot spots can lead to irreversible crystallization of the catalyst resulting in deactivation of the latter. The fixed bed is loaded using the specific method of dense catalyst loading. This method is known to those skilled in the art. It makes it possible to obtain an optimal distribution of the catalyst inside the reactor while avoiding fading (channeling) during the reaction and the attrition of the catalyst. In general, the apparent mass density of the catalyst in the fixed bed is greater than the theoretical mass density of the latter. The apparent mass density is determined according to standard ASTM D1895.

Preferably, said adiabatic reactor is a gas phase fluorination reactor.

The present invention makes it possible to implement a process for producing 2,3,3,3tetrafluoropropene with a larger quantity of catalyst. In addition, controlling and controlling the temperature radially and longitudinally makes it possible to maintain a conversion and a selectivity of the reactions.

According to a third aspect of the invention, an installation for manufacturing the

2,3,3,3-tetrafluoropropene is provided. Preferably, the installation comprises an adiabatic reactor 101 according to the present invention; a first reaction flow supply device for said reactor connected to the cover of said reactor; a second reaction flow supply device for said reactor connected to the side wall of said reactor and disposed between the first fixed bed and the second fixed bed; a device for collecting and purifying the outlet flow from said reactor.

According to a first embodiment, the reaction flow supply device connected to the cover of said reactor comprises a supply line for hydrofluoric acid 104, a supply line 106 for said stream A, and a mixing device 107 for hydrofluoric acid and stream A. In addition, the reaction flow supply device connected to the side wall of said reactor of said reactor comprises a hydrofluoric acid supply line 104 and a stream supply line C 105.

According to a second embodiment, the reaction flow supply device connected to the cover of said reactor comprises a line for supplying hydrofluoric acid 104 and a line for supplying said stream C 105. In addition, the device for reaction flow supply connected to the side wall of said reactor comprises a hydrofluoric acid supply line 104, a supply line 106 of stream A and a device 107 for mixing hydrofluoric acid and stream A

In the two embodiments described above, said installation also comprises a heat exchanger 108 supplied by the outlet stream 108 ′ and connected to a first distillation column 109. Preferably, said installation also comprises a compressor 113 supplied by the stream from said first distillation column 109. Preferably, said installation comprises a second distillation column 114 supplied with a stream from the compressor 113. Said second distillation column 114 aims to remove all or part of the HCl present in the stream routed to it. Said installation can also include a plurality of other distillation columns for purifying the 2,3,3,3tetrafluoropropene and removing impurities.

An installation according to a particular embodiment of the present invention is illustrated in FIG. 5a and described below. The installation comprises an adiabatic reactor 101 comprises a first fixed bed 102 and a second fixed bed 103. The first fixed bed 102 is arranged above the second fixed bed 103. The reaction flow supply device for the reactor comprises a line of supply of hydrofluoric acid 104 and a line for supplying stream A 106. The installation also comprises a device 107 for mixing hydrofluoric acid and said stream A. The mixing device is preferably a static mixer. Thus, hydrofluoric acid and said stream A are mixed, sprayed and vaporized in said mixing device 104 before being introduced into said reactor 101 between the first fixed bed 102 and the second fixed bed 103. The device for supplying reaction flow of the reactor comprises a line for supplying hydrofluoric acid 104, at least one line for supplying 105 with stream C. Preferably, the flow 108 ′ collected at the outlet of the reactor comprises 2-chloro-3,3, 3trifluoropropene, HF, HCl, 2,3,3,3-tetrafluoropropene and optionally 1,1,1,2,2pentafluoropropane. The heat exchanger 108 is able to cool the outlet stream 108 'to form a cooled stream. The outlet stream 108 ′ is conveyed to a cooling device 108 to be cooled to a temperature from 0 ° C to 70 ° C before being introduced into a distillation column 109 via a pipe 110. The distillation column 109 is configured to allow separation between hydrochloric acid, 2,3,3,3tetrafluoropropene and optionally 1,1,1,2,2-pentafluoropropane, on the one hand, and hydrofluoric acid and 2 on the other hand chloro-3,3,3-trifluoropropene. The stream of HF and 2-chloro-3,3,3trifluoropropene is recovered at the bottom of the distillation column 109 and recycled via line 112 to the reactor 101, preferably the stream is recycled upstream of the first fixed bed. The stream comprising 2,3,3,3-tetrafluoropropene and hydrochloric acid and optionally

1,1,1,2,2-pentafluoropropane is recovered at the top of the distillation column 109 to be conveyed by a line 111 to a compressor 113. The compressor makes it possible to compress the current comprising 2,3,3,3-tetrafluoropropene and hydrochloric acid and optionally 1,1,1,2,2-pentafluoropropane at a pressure between 10 and 25 bara. The stream thus compressed is conveyed to a second distillation column 114. This is configured so as to separate the 2,3,3,3-tetrafluoropropene on one side and optionally

1.1.1.2.2- pentafluoropropane and the other hydrochloric acid. The hydrochloric acid is recovered is at the head of the distillation column 114 to be conveyed to a purification device 117 by the line 115. The hydrochloric acid purification device 117 is a device known from the prior art, for example from WO 2015/079137. 2,3,3,3tetrafluoropropene and optionally 1,1,1,2,2-pentafluoropropane is recovered at the bottom of distillation column 114 to be conveyed by line 116 to a third distillation column 118. The distillation column 118 aims to separate 2,3,3,3-tetrafluoropropene from

1.1.1.2.2- pentafluoropropene possibly present in the outlet stream 108 '. 2,3,3,3tetrafluoropropene is recovered at the top of the distillation column to be conveyed to a purification device 120 via line 119. The 1,1,1,2,2-pentafluoropropene recovered at the bottom of the distillation column is recycled to the first reactor 101 via line 121, preferably the current is recycled upstream of the first fixed bed. The purification device 120 comprises in particular a device for removing HF and one or more distillation columns capable of purifying the stream comprising the 2,3,3,3-tetrafluoropropene of impurities which it could contain, such as for example residual 1,1,1,2,2-pentafluoropropane and / or

1,3,3,3-tetrafluoropropene. The HF removal device removes the residual HF which can be recycled to the first reactor 101 (not shown). The HF elimination device may be able to allow the settling of HF or the absorption of HF. Residual impurities such as for example 1,1,1,2,2-pentafluoropropane and / or 1,3,3,3-tetrafluoropropene can be removed from 2,3,3,3-tetrafluoropropane by distillation, in particular distillation extractive. The two streams from the bottom of the distillation columns 109 and 118 can be mixed before being introduced into the reactor 101. In addition, before being introduced into the reactor 101, the electrical conductivity of the two streams or of the mixture of those this is measured by the conductivity meter 122. These two recycled streams can constitute stream C described in the present application.

An installation according to a particular embodiment of the present invention is illustrated in FIG. 5b and described below. The installation comprises an adiabatic reactor 101 comprises a first fixed bed 102 and a second fixed bed 103. The first fixed bed 102 is arranged above the second fixed bed 103. The reaction flow supply device for the reactor comprises a line d supply of hydrofluoric acid 104 and a line for supplying stream A 106. The installation also comprises a device 107 for mixing hydrofluoric acid and said stream A. The mixing device is preferably a static mixer. Thus, hydrofluoric acid and said stream A are mixed, sprayed and vaporized in said mixing device 104 before being introduced into said reactor 101 upstream of the first fixed bed 102. The reaction flow supply device for the reactor comprises a supply line for hydrofluoric acid 104, and a supply line 105 for stream C, both arranged between the first fixed bed and the second fixed bed. Preferably, the stream 108 'collected at the outlet of the reactor comprises 2-chloro-3,3,3-trifluoropropene, HF, HCl, 2,3,3,3-tetrafluoropropene and optionally 1,1,1,2,2- pentafluoropropane. The heat exchanger 108 is able to cool the outlet stream 108 'to form a cooled stream. The outlet stream 108 ′ is conveyed to a cooling device 108 to be cooled to a temperature from 0 ° C to 70 ° C before being introduced into a distillation column 109 via a pipe 110. The distillation column 109 is configured to allow separation between hydrochloric acid, 2,3,3,3-tetrafluoropropene and optionally 1,1,1,2,2-pentafluoropropane, and hydrofluoric acid on the other hand and 2-chloro-3,3,3-trifluoropropene. The stream of HF and of 2-chloro-3,3,3-trifluoropropene is recovered at the bottom of the distillation column 109 and recycled via line 112 to the reactor 101, preferably the stream is recycled upstream of the first fixed bed and between the first fixed bed and the second fixed bed, in particular between the first catalytic bed and the second catalytic bed. The stream comprising 2,3,3,3-tetrafluoropropene and hydrochloric acid and optionally 1,1,1,2,2-pentafluoropropane is recovered at the head of distillation column 109 to be conveyed by a line 111 to a compressor 113. The compressor makes it possible to compress the stream comprising 2,3,3,3-tetrafluoropropene and hydrochloric acid and optionally 1,1,1,2,2-pentafluoropropane at a pressure between 10 and 25 bara. The stream thus compressed is conveyed to a second distillation column 114. This is configured so as to separate on one side the 2,3,3,3-tetrafluoropropene and optionally 1,1,1,2,2-pentafluoropropane and on the other hydrochloric acid. The hydrochloric acid is recovered and is at the head of the distillation column 115 to be conveyed to a purification device 117 via line 115. The hydrochloric acid purification device 117 is a device known from the prior art, for example from WO 2015/079137. The

2,3,3,3-tetrafluoropropene and optionally 1,1,1,2,2-pentafluoropropane is recovered at the bottom of distillation column 114 to be conveyed by line 116 to a third distillation column 118. The distillation column 118 aims to separate 2,3,3,3tetrafluoropropene from 1,1,1,2,2-pentafluoropropene possibly present in the outlet stream 108 '. 2,3,3,3-tetrafluoropropene is recovered at the top of the distillation column to be conveyed to a purification device 120 via line 119. The 1,1,1,2,2pentafluoropropene recovered at the bottom of the distillation column is recycled to the reactor 101 via line 121, preferably the current is recycled between the first fixed bed and the second fixed bed. The purification device 120 comprises in particular a device for removing HF and one or more distillation columns capable of purifying the stream comprising 2,3,3,3tetrafluoropropene from impurities which it could contain, such as for example 1 , 1,1,2,2pentafluoropropane residual and / or 1,3,3,3-tetrafluoropropene. The HF removal device removes the residual HF which can be recycled to the first reactor 101 (not shown). The HF elimination device may be able to allow the settling of HF or the absorption of HF. Residual impurities such as, for example 1,1,1,2,2-pentafluoropropane and / or 1,3,3,3-tetrafluoropropene can be removed from 2,3,3,3-tetrafluoropropane by distillation, in particular distillation extractive. The two streams from the bottom of the distillation columns 109 and 118 can be mixed before being introduced into the reactor 101. In addition, before being introduced into the reactor 101, the electrical conductivity of the two streams or of the mixture of those -this is measured by the conductivity meter 122.

Claims (12)

claims 1. Method for producing 2,3,3,3-tetrafluoropropene in an adiabatic reactor comprising a first fixed bed and a second fixed bed, said method comprising the steps: 5 i) bringing into contact in the gas phase, in the presence or not of a catalyst, of hydrofluoric acid with a stream A comprising at least one chlorine compound selected from the group consisting of 1,1,1,2,3-pentachloropropane, 2,3-di € hlorO'l _i l, l-trifluoropropain, 2,3,3,3-tetrachloropropene and 1,1,2.,. 3-tetrachloropiOpene to produce a stream B comprising 2-chloro-3,3,3-trifluoropropene, Ii) contacting in the gas phase in the presence of a catalyst of a stream C comprising S-chloro-SAS-tdfluoropropene with hydrofluoric acid to produce a stream D comprising 2,3,3,3-tetrafluoropropene; and iii) recovery at the outlet of the reactor of a stream E comprising 2,3,3,3tetrafluoropropene, 2-chloro-3,3,3-trlfluoropropene, HCl, HF and optionally 1,1,1,2,215 pentafluoropropane; characterized in that the temperature at the inlet of the first fixed bed is between BOO’C and 4OCFC and the longitudinal temperature difference between the inlet of the first fixed bed and the outlet of the first fixed bed is less than 20X; 20 - the temperature at the inlet of the second fixed bed is between 300’C and 400 * C and the longitudinal temperature difference between the inlet of the second fixed bed and the outlet of the second fixed bed is less than 2GX < 2. Method according to claim 1 characterized in that said first fixed bed is arranged au- 25 above said second fixed bed and the temperature at the outlet of the first fixed bed is higher than the temperature at the inlet of the second fixed bed. 3. Method according to any one of the preceding claims, characterized in that step i) is implemented in the first fixed bed, step il) is implemented in the second fixed bed 30 and the current C is introduced into the reactor between the first and the second fixed bed. 4. Method according to the preceding claim characterized in that the temperature at the inlet of the first fixed bed is between 340'C and SSCP'C and the temperature at the inlet of the second fixed bed is between 33 (7'0 and 360 * C. 5 5. Method according to any one of the preceding claims 1 or 2 characterized in that step î) is implemented in the second fixed üt, step ii) is implemented in the first fixed bed and the current A is introduced into the reactor between the first and the second fixed bed. 6. Method according to the preceding claim characterized in that the temperature at the inlet of the second fixed bed is between 340 ° C and 3S0X and the temperature at the inlet of the first fixed bed is between 33Q * C and 3 & TC 7. Method according to any one of the preceding claims, characterized in that the HF / 2-chloro-3,3,3-trifluoropropene molar ratio in step ii) or the molar ratio between HP and said 15 chlorine compound in step i) or both is adjusted so as to keep the longitudinal temperature difference between the inlet and the outlet of the fixed bed considered less than 20 * C> 8. Method according to any one of the preceding claims, characterized in that the HF / 2-chloro-3,3,3'trifluoropropene molar ratio, in step ii), is greater than or equal to S, 20 advantageously greater than or equal to 10, preferably greater than or equal to 12. 9. Method according to any one of the preceding claims, characterized in that the HF / chlorine compound molar ratio, in step i), is greater than or equal to 5, advantageously greater than or equal to 10, preferably greater than or equal to 12. 10. A method according to any one of the preceding claims characterized in that said reactor comprises side walls, these comprising an inner layer, an intermediate layer disposed on said inner layer and an insulating layer disposed on said intermediate layer; and the difference in radial temperature between a point in the center of the 30 fixed bed considered and a point located in the radial plane at the level of the inner layer of the side wall of the reactor is less than 1GX. 11. Method according to any one of the preceding claims, characterized in that said reactor comprises side walls, these comprising an inner layer, an intermediate layer disposed on said inner layer and an insulating layer disposed on said intermediate layer; said insulating layer being made of an M2 heat-insulating material of which 5 the thickness varies between 1 mm and 500 mm. 12. Method according to the preceding claim characterized in that the heat-insulating material M2 is selected from the group consisting of rock wool, glass wool, silicate fibers, calcium-magnesium silicates, calcium silicates, microporous insulators , glass 10 cellular, expanded perlite, exfoliated vermiculite.