FR3096984A1 - High purity 1,1,1,2,3,3-hexafluoropropane, its manufacturing process and use - Google Patents

Abstract

The present invention relates to a process for the manufacture of high purity 1,1,1,2,3,3-hexafluoropropane and a composition mainly comprising 1,1,1,2,3,3-hexafluoropropane, suitable for use as cleaning agent in the semiconductor industry.

Description

High purity 1,1,1,2,3,3-hexafluoropropane, process for its manufacture and use thereof

The present invention relates to a process for the manufacture of high purity 1,1,1,2,3,3-hexafluoropropane and a composition containing mainly 1,1,1,2,3,3-hexafluoropropane, suitable for use as cleaning agent in the semiconductor industry.

1,1,1,2,3,3-hexafluoropropane (HFC-236ea) is a hydrofluorocarbon and has been described as a raw material to manufacture 1,1,1,2,3-pentafluoropropene or as an intermediate in the manufacture of 1,1,1,2,3-pentafluoropropane and/or 1,1,1,2-tetrafluoropropene. Mention may in particular be made of documents US 5679875, US 539600, US 8359964 and US 8389779).

1,1,1,2,3,3-hexafluoropropane can in particular be prepared by catalytic hydrogenation of hexafluoropropene.

It can also be prepared by high temperature pyrolysis of chlorodifluoromethane (CHClF ₂ ) in the presence of 1,1,1,2-tetrafluoroethane. Mention may be made, for example, of document WO 1996029296.

1,1,1,2,3,3-hexafluoropropane can also be prepared according to a process during which at least one tetrafluorochloropropene is obtained from the dechlorofluorination of 1,1,1,2,2-pentafluoro-3, 3-dichloropropane (HCFC-225ca) and/or 1,1,2,2,3-pentafluoro-1,3-dichloropropane (HCFC-225cb) with hydrogen in the presence of an oxide catalyst metallic. Then the product(s) tetrafluorochloropropene(s) (1,1,1,2-tetrafluoro-3-chloro-2-propene (HCFO-1224yd), 1,1,2,3-tetrafluoro-1-chloro -2-propene (HCFO-1224ye) and 1,1,2,3-tetrafluoro-3-chloro-1-propene (HCFO-1224yc)) is or are then fluorinated in the presence of a catalyst to lead to the HFC-236ea. Mention may be made, for example, of documents US 5532418.

Finally, according to US 5563304, 1,1,1,2,3,3-hexafluoropropane can be prepared by reacting 1,2,3,3,3-pentafluoropropene (HFO-1225ye) with hydrogen fluoride at a elevated temperature, over a catalyst selected from the group consisting of aluminum fluoride, fluorinated aluminum oxide, aluminum fluoride supported metals, fluoridated aluminum oxide supported metals and catalysts comprising trivalent chromium .

The present application relates first to a process for the manufacture of high purity 1,1,1,2,3,3-hexafluoropropane.

The process according to the present invention comprises supplying a flux comprising at most 99% by weight of the 1,1,1,2,3,3-hexafluoropropane and then treating said flux to give a composition comprising at least 99.4% by weight of HFC-236ea, and at most 0.6% by weight of at least one compound chosen from hexafluoropropene, cis/trans-1,2,3,3,3-pentafluoropropene (HFO-1225ye(Z /E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,2,3,3-pentafluoropropene (HFO-1225yc), 2,3,3,3- tetrafluoropropene (HFO-1234yf), cis/trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z/E)), 3,3,3-trifluoropropene (HFO-1243zf), 1,1 ,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,1,1,3-tetrafluoropropane (HFC-254fb), 1,1,1-trifluoropropane (HFC-263fb), 1,1,2-trifluoroethane (HFC-143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane (cyclo- C ₄ F ₈ ), cis/trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO-356mff(Z/E)), water, hydrogen, nitrogen, oxygen, CO ₂ , CO and HF. This treatment comprises at least one separation and/or purification step.

The stream comprising at most 99% by weight of the 1,1,1,2,3,3-hexafluoropropane can be obtained from any method for preparing 1,1,1,2,3,3-hexafluoropropane. However, the method of catalytic hydrogenation of hexafluoropropene is preferred.

As separation, we can cite condensation, evaporation, settling, absorption, washing, liquid-liquid extraction.

As purification, mention may be made of photochlorination, distillation, for example extractive distillation, azeotropic distillation, adsorption on solid and more particularly adsorption on molecular sieve, alumina or activated carbon and membrane separation

The subject of the present invention is more particularly a process for the manufacture of 1,1,1,2,3,3-hexafluoropropane comprising (i) at least one stage of hydrogenation of hexafluoropropene (HFP) to give a stream comprising 1,1,1,2,3,3-hexafluoropropane, optionally unreacted hexafluoropropene, unreacted hydrogen, cis/trans-1,2,3,3,3-pentafluoropropene (HFO-1225ye (Z/E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,2,3,3-pentafluoropropene (HFO-1225yc), 2,3,3, 3-tetrafluoropropene (HFO-1234yf), cis/trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z/E)), 3,3,3-trifluoropropene (HFO-1243zf), 1 ,1,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,3,3 -pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,1,1,3 -tetrafluoropropane (HFC-254fb), 1,1,1-trifluoropropane (HFC-263fb), 1,1,2-trifluoroethane (HFC-143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane ( cyclo-C ₄ F ₈ ), cis/trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO-356mff(Z/E)), water and HF (ii) at least one separation and/or purification step to give a composition comprising at least 99.4% by weight of HFC-236ea, and at most 0.6% by weight of at least one compound chosen from hexafluoropropene, cis/trans-1,2,3,3,3-pentafluoropropene (HFO-1225ye(Z/E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,2,3,3-pentafluoropropene (HFO-1225yc), 2,3,3,3-tetrafluoropropene (HFO-1234yf), cis/trans-1,3,3,3-tetrafluoropropene (HFO- 1234ze(Z/E)), 3,3,3-trifluoropropene (HFO-1243zf), 1,1,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1,1 ,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,1,1,3-tetrafluoropropane (HFC-254fb), 1,1,1-trifluoropropane (HFC-263fb), 1,1 ,2-trifluoroethane (HFC-143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane (cyclo-C ₄ F ₈ ), cis/trans-1,1,1,4,4,4-hexafluoro -2-butene (HFO-356mff(Z/E)), water, hydrogen, nitrogen, oxygen, CO ₂ , CO and HF.

The separation and/or purification steps can be chosen from the following:

• Adsorption, for example on activated alumina and/or molecular sieve
• Distillation,
• Membrane Separation,
• Water wash,
• Photochlorination.

The separation and/or purification steps can comprise at least one adsorption step, preferably on activated alumina and/or molecular sieve, and at least one distillation step.

Preferably, the separation and/or purification steps may comprise (a) at least one step for eliminating HF by adsorption on activated alumina or by membrane separation, and/or (b) at least one step for eliminating water by adsorption on a molecular sieve whose pore size is between 3Å and 5Å, and/or (c) at least one distillation step.

Advantageously, the separation and/or purification steps successively comprise (a) at least one HF removal step, (b) at least one water removal step and (c) at least one distillation step.

The distillation step (c) can be carried out by a distillation column which makes it possible to obtain the purified HFC-236ea at the top of the column and to recover heavy compounds at the bottom of the column or by a distillation column which makes it possible to recover light compounds at the top of the column, the purified HFC-236ea in side withdrawal from this column and heavy compounds at the bottom of this column.

At the end of the distillation step, the HFC-236ea can undergo a final purification (d) on a molecular sieve with a pore size greater than or equal to 4Å.

Distillation step (c) can be carried out at a pressure of between 1 and 15 bar absolute, advantageously between 3 and 10 bar absolute.

Distillation step (c) can also be carried out using two distillation columns. The first distillation column can be used to remove light compounds such as for example HFP, HFO-1234yf, HFO-1243zf, HFO-1225ye(Z/E), HFO-1234ze(Z/E), HFO-1225zc, HFC -227ea, HFC-236fa, HFC-254eb, cyclo-HFP while the second distillation column can be used to remove heavy compounds such as for example HFC-245fa, HFC-245eb, HFO-356mff(Z/E) , HFC-254fb. The purified HFC-236ea is thus obtained at the top of the second distillation column. Optionally, these two distillation columns or the distillation column with side withdrawal can be advantageously replaced by a single wall distillation column (divided wall column) which offers both capital and energy savings.

According to another preferred embodiment, the HF removal step (a) can be carried out by washing with water optionally followed by washing with a solution of soda or potash to neutralize the traces of residual acidity.

According to another preferred embodiment, the HF removal step (a) can be preceded by a step (a0) of photochlorination of the olefins present in the HFC-236ea. In this case, the HF elimination step (a) will very preferably be washing with an aqueous solution making it possible to absorb not only the HF but also the HCl formed and the residual Cl ₂ during the photochlorination step.

The photochlorination step (a0) can be carried out in the liquid phase or in the gas phase in a photochlorination reactor equipped with a lamp and a transparent window. A mixture of chlorine and the stream comprising HFC-236ea, containing unsaturated fluorinated products is introduced into the photochlorination reactor. Preferably, the reaction is carried out in the gas phase and the resulting stream, containing the HFC-236ea and the saturated chlorofluorinated products, is sent directly to the next purification step.

Preferably, the hydrogenation step is carried out in the presence of a catalyst.

As catalyst, mention may in particular be made of metals such as Pd, Ru, Pt, Rh, Ir, Fe, Co, Ni, Cu, Ag, Re, Os, Au, Ge, optionally supported Te. As support, mention may in particular be made of carbon, alumina, fluorinated alumina, AlF ₃ , oxides, oxyfluorides and fluorides of Cr, Ti, Zr, Mg, Zn, silica and silicon carbide.

The quantity of metals present in the catalyst, when the latter is supported, can be between 0.001 and 10% by weight, preferably between 0.001 and 0.2% by weight.

The hydrogenation step is advantageously carried out in the presence of Pd supported on alumina, preferably in the alpha polymorphic form.

The hydrogenation step can be carried out both in the liquid phase and in the gas phase. The gas phase is however preferred.

The hydrogenation step is preferably carried out in the presence of hydrogen, advantageously with a hydrogen/HFP molar ratio of between 1 and 50, and most particularly between 2 and 15.

The hydrogenation step is preferably carried out at a temperature between 50 and 200°C, preferably between 80 and 120°C.

Preferably, the temperature at the inlet to the hydrogenation stage reactor is between 30 and 100° C., advantageously between 40 and 80° C.

The contact time of the hydrogenation step, defined as the ratio of the volume of the catalytic bed to the volume flow rate of the total flow under normal temperature and pressure conditions, is preferably between 0.1 s and 20 s and advantageously between 0.5 and 5 s.

The hydrogenation step is preferably carried out at an absolute pressure between 0.5 and 20 bar and advantageously between 1 and 5 bar.

Preferably, the hydrogenation step is carried out in the presence of a diluent which can be co-introduced with the reactants into the reaction medium. The diluent is an inert gas that does not react under the conditions of the hydrogenation step. As a diluent, mention may be made of nitrogen, helium or argon.

The molar ratio of the diluent/reagents at the inlet of the hydrogenation stage reactor can be between 100:1 and 1:1, preferably between 10:1 and 1:1, advantageously between 5:1 and 1 :1.

The diluent can be the hydrogenation product which is HFC-236ea. In this case, part of the gaseous effluent from the reactor comprising HFC-236ea, unreacted hydrogen and possibly unreacted hexafluoropropene, 1,1,1,2,3-pentafluoropropane (HFC- 245eb) and 1,1,1,2-tetrafluoropropane (HFC-254eb) is recycled and the other part of the gaseous effluent from the reactor is subjected to a separation and/or purification stage.

The gas stream comprising the recycling loop and the reactants can be preheated before introduction into the reactor.

According to the process of the invention, an adiabatic reactor is preferably used.

The part of the gaseous effluent recycled to the reactor preferably represents at least 90% by volume of all of the effluent at the outlet of the reactor, advantageously at least 93% by volume. Particularly preferably, the part of the effluent recycled to the reactor represents between 94 and 98% by volume of the total effluent at the outlet of the reactor.

The stream at the end of the hydrogenation stage can be subjected to a condensation stage under conditions such that the unreacted hydrogen is not condensed and that a part of HFC-236ea formed at the step (i) is condensed.

Preferably, the condensation step is implemented at a temperature between 0 and 50° C. and at a pressure between 0.5 and 20 bar absolute, advantageously between 1 and 5 bar absolute.

Preferably, the condensation step is implemented under conditions such that between 1 and 30% of HFC-236ea leaving the reactor is condensed and advantageously between 2 and 10% is condensed.

The non-condensed fraction is then recycled to the hydrogenation step (i) after optional heating.

The condensed fraction is then evaporated before being sent to the separation and/or purification stage described above.

During the hydrogenation reaction, the cleavage of the carbon-fluorine bond can be observed, thus leading to the formation of a small quantity of HF which can be harmful to the use of HFC-236ea in the semi-hydrocarbon industry. drivers.

After separation of the stream at the end of step (i), the stream comprising mainly HFC-236ea can be subjected to at least one washing step to reduce the HF content. However, the residual presence of water can also make it unsuitable for use in the semiconductor industry.

A subject of the present invention is also a composition comprising at least 99.4% by weight of HFC-236ea, and at most 0.6% by weight of at least one compound chosen from hexafluoropropene, cis/trans-1 ,2,3,3,3-pentafluoropropene (HFO-1225ye(Z/E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,2,3,3- pentafluoropropene (HFO-1225yc), 2,3,3,3-tetrafluoropropene (HFO-1234yf), cis/trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z/E)), 3 ,3,3-trifluoropropene (HFO-1243zf), 1,1,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1,1,3,3,3-hexafluoropropane (HFC -236fa), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,1,1,3-tetrafluoropropane (HFC-254fb), 1,1,1-trifluoropropane (HFC-263fb), 1,1,2-trifluoroethane (HFC-143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane (cyclo-C ₄ F ₈ ), cis/trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO-356mff(Z /E)), water, hydrogen, nitrogen, oxygen, CO ₂ , CO and HF.

Preferably, the HFC-236ea is present in the composition in an amount greater than or equal to 99.9% by weight, advantageously greater than or equal to 99.99% by weight and even more preferably, greater than or equal to 99.995% by weight. weight.

According to one embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of the HFC-236ea and at most 0.1% by weight of HF, preferably at most 1 ppm of HF and advantageously at most 0.1 ppm of HF.

According to one embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea and at most 190 ppm of water, preferably at most 10 ppm of water and advantageously at most 1 ppm of water.

According to one embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea and at most 5 ppm of hydrogen, preferably at most 1 ppm of hydrogen, more preferably at most 0.3 ppm of hydrogen and advantageously at most 0.1 ppm of hydrogen.

According to one embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea and at most 3500 ppm of nitrogen, preferably at most 150 ppm nitrogen, more preferably at most 70 ppm nitrogen and advantageously at most 5 ppm nitrogen.

According to one embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea and at most 1000 ppm of oxygen, preferably at most 20 ppm oxygen, more preferably at most 10 ppm oxygen and advantageously at most 2 ppm oxygen.

According to one embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea and at most 125 ppm of CO ₂ , preferably at most 20 ppm of CO ₂ , more preferably at most 5 ppm of CO ₂ and advantageously at most 2 ppm of CO ₂ .

According to one embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea and at most 90 ppm of CO , preferably at most 15 ppm of CO, more preferably at most 3 ppm of CO and advantageously at most 1.5 ppm of CO.

According to a preferred embodiment, the composition comprises at least 99.4%, preferably 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea, at most 190 ppm of water and at most 0.1% by weight of HF, preferably at most 10 ppm of water and at most 1 ppm of HF and advantageously at most 1 ppm of water and at most 0.1 ppm of HF.

Whatever the embodiment, the composition according to the invention may also comprise at most 1000 ppm, preferably at most 100 ppm and advantageously at most 10 ppm of at least one compound chosen from hexafluoropropene, cis/ trans-1,2,3,3,3-pentafluoropropene (HFO-1225ye(Z/E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,2,3 ,3-pentafluoropropene (HFO-1225yc) and 3,3,3-trifluoropropene (HFO-1243zf) and at most 5000 ppm, preferably at most 500 ppm and advantageously at most 50 ppm of at least one compound chosen from hexafluorocyclopropane (cyclo-C ₃ F ₆ ) and octafluorocyclobutane (cyclo-C ₄ F ₈ ).

Whatever the embodiment, the composition according to the invention may also comprise at most 6000 ppm, preferably at most 3000 ppm and advantageously at most 1000 ppm of total organic impurities.

EXPERIMENTAL PART

Trial 1

325g of a mixture (previously washed) comprising approximately 97.8% by weight of HFC-236ea and having the following composition:

Table 1 Compound Concentration (% weight) 2,3,3,3-tetrafluoropropene (HFO-1234yf) 0.0984 1,3,3,3-tetrafluoropropene(HFO-1234ze) 0.0013 1,1,1,2,3,3,3-peptafluoropropane (HFC-227ea) 0.0117 1,1,1-trifluoropropane (HFC-263fb) 0.0019 1,1,1,3,3,3-hexafluoropropane (HFC-236fa) 0.0246 1,1,1,2-tetrafluoropropane (HFC-254eb) 0.0581 HFC-236ea: 97.8667 1,1,1,3,3-pentafluoropropane (HFC-245fa) 0.4825 1,1,1,2,3-pentafluoropropane (HFC-245eb) 1.3576 1,1,1,4,4,4-hexafluoro-2-butene (HFO-356mff) 0.0244 1,1,1,3-tetrafluoropropane (HFC-254fb) 0.0728

The distillation is carried out at atmospheric pressure. A total of 12 fractions are withdrawn with a head temperature of 10°C.

Table 2 summarizes the composition in % by weight of fractions 2 to 11).

Chart 2 Component #2
17.1g #3
35.0g #4
51.2g #5
42.4g #6
26.3g #7
17.1g #8
12.8g #9
16.2g #10
31.3g #11
16.7g HFC-227ea 0.0708 0.0247 0.0063 0.0013 0.0004 0.0001 HFC-263fb 0.0043 0.0032 0.0024 0.0016 0.0015 0.0004 0.0011 0.0009 0.0005 0.0003 HFC-236fa 0.1053 0.0644 0.0319 0.0157 0.0075 0.0093 0.0040 0.0025 0.0011 0.0007 HFC-254eb 0.1394 0.112 0.0852 0.0599 0.0458 0.0417 0.0269 0.0193 0.0113 HFC-236ea 99.6147 99.7282 99.7754 99.7942 99.7760 99.7572 99.7219 99.6821 99.5781 99.1932 HFC-245fa 0.0451 0.0486 0.0681 0.0831 0.1137 0.1216 0.1457 0.1874 0.2538 0.4694 HFC-245eb 0.0188 0.0188 0.0307 0.0441 0.054 0.0698 0.0826 0.0987 0.1433 0.3176 HFC-356mff 0.0004 0.0008 0.0014 0.0026 0.0046

Purity fractions > 99.7% are pooled and dried by passage through a 4Å molecular sieve to form a final batch.

The analysis of this final batch indicates an HFC-236ea purity > 99.7% by weight with a water content of 11ppm. No trace of acidity is detected.

Trial 2

A gas stream comprising 99.8% by weight of HFC-236ea, 217 ppm of HF, 27 ppm of water is passed at room temperature through a bed (length/diameter ratio=10) of alumina spheres HF- 200 BASF (1/8'' spheres) and a bed of siliporite-type molecular sieves with a pore size of 3Å, for 8 hours. The flow at the outlet is almost free of HF (< 1 ppm) and water (<10ppm).

Claims (13)

A method of making high purity 1,1,1,2,3,3-hexafluoropropane comprising (i) providing a stream comprising up to 99% by weight of the 1,1,1,2,3,3- hexafluoropropane and (ii) treating said stream to give a composition comprising at least 99.4% by weight of HFC-236ea, and at most 0.6% by weight of at least one compound selected from hexafluoropropene, cis /trans-1,2,3,3,3-pentafluoropropene (HFO-1225ye(Z/E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,2, 3,3-pentafluoropropene (HFO-1225yc), 2,3,3,3-tetrafluoropropene (HFO-1234yf), cis/trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z/E) ), 3,3,3-trifluoropropene (HFO-1243zf), 1,1,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1,1,3,3,3 -hexafluoropropane (HFC-236fa), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1 ,2-tetrafluoropropane (HFC-254eb), 1,1,1,3-tetrafluoropropane (HFC-254fb), 1,1,1-trifluoropropane (HFC-263fb), 1,1,2-trifluoroethane (HFC -143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane (cyclo-C ₄ F ₈ ), cis/trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO -356mff(Z/E)), water, hydrogen, nitrogen, oxygen, CO ₂ , CO and HF, preferably the treatment comprising at least one step separation and/or purification. Process according to Claim 1, characterized in that it comprises (i) at least one stage of hydrogenation, preferably catalytic, of hexafluoropropene to give a stream comprising 1,1,1,2,3,3-hexafluoropropane , optionally unreacted hexafluoropropene, unreacted hydrogen, cis/trans-1,2,3,3,3-pentafluoropropene (HFO-1225ye(Z/E)), 1,1,3, 3,3-pentafluoropropene (HFO-1225zc), 1,1,2,3,3-pentafluoropropene (HFO-1225yc), 2,3,3,3-tetrafluoropropene (HFO-1234yf), cis/trans- 1,3,3,3-tetrafluoropropene (HFO-1234ze(Z/E)), 3,3,3-trifluoropropene (HFO-1243zf), 1,1,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1 ,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,1,1,3-tetrafluoropropane (HFC-254fb), 1,1,1 -trifluoropropane (HFC-263fb), 1,1,2-trifluoroethane (HFC-143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane (cyclo-C ₄ F ₈ ), cis/trans-1 ,1,1,4,4,4-hexafluoro-2-butene (HFO-356mff(Z/E)), water, nitrogen, oxygen, CO2, CO and l 'HF;(ii) at least one separation and/or purification step to give a composition comprising at least 99.4% by weight of the HFC-236ea, and at most 0.6% by weight of at least one compound selected from hexafluoropropene, cis/trans-1,2,3,3,3-pentafluoropropene (HFO-1225ye(Z/E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc) , 1,1,2,3,3-pentafluoropropene (HFO-1225yc), 2,3,3,3-tetrafluoropropene (HFO-1234yf), cis/trans-1,3,3,3-tetrafluoropropene( HFO-1234ze(Z/E)), 3,3,3-trifluoropropene (HFO-1243zf), 1,1,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1 ,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb ), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,1,1,3-tetrafluoropropane (HFC-254fb), 1,1,1-trifluoropropane (HFC-263fb), 1 ,1,2-trifluoroethane (HFC-143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane (cyclo-C ₄ F ₈ ), cis/trans-1,1,1,4,4,4 -hexafluoro-2-butene (HFO-356mff(Z/E)), water, nitrogen, oxygen, CO2, CO and HF. Process according to Claim 1 or 2, characterized in that the separation step is chosen from condensation, evaporation, settling, absorption, washing and liquid-liquid extraction. Process according to any one of the preceding claims, characterized in that the purification stage is chosen from photochlorination, distillation, preferably extractive distillation and/or azeotropic distillation, adsorption on solid, preferably adsorption on molecular sieve, alumina or activated carbon and on membrane. Process according to any one of the preceding claims, characterized in that the treatment of the said stream comprises at least one step of removing HF, preferably on activated alumina, and/or at least one step of removing water, preferably by adsorption on a sieve and advantageously a 3 to 5 A sieve and/or at least one distillation step. Process according to Claim 4 or 5, characterized in that the distillation step is carried out by using two distillation columns. Process according to Claim 5 or 6, characterized in that it comprises a photochlorination stage before the HF elimination stage. Process according to any one of the preceding claims, characterized in that the hydrogenation stage is carried out in the presence of a diluent. Process according to any one of the preceding claims, characterized in that at the end of stage (i) the stream is subjected to a stage of partial condensation to lead to a condensed fraction and a non-condensed fraction which is recycled to the hydrogenation step. Process according to Claim 9, characterized in that the condensed fraction is evaporated and then subjected to at least one stage of separation and/or purification. Composition comprising at least 99.4% by weight of HFC-236ea, and at most 0.6% by weight of at least one compound chosen from hexafluoropropene, 1,1,1,2-tetrafluoropropane, 1,1 ,1,2,3-pentafluoropropane, water, HF. Composition comprising at least 99.4% by weight of HFC-236ea, and at most 0.6% by weight of at least one compound chosen from hexafluoropropene, cis/trans-1,2,3,3,3 -pentafluoropropene (HFO-1225ye(Z/E)), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,2,3,3-pentafluoropropene (HFO-1225yc), 2,3,3,3-tetrafluoropropene (HFO-1234yf), cis/trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z/E)), 3,3,3-trifluoropropene (HFO -1243zf), 1,1,1,2,3,3,3-peptafluoropropane (HFC-227ea), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1 ,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1 ,1,1,3-tetrafluoropropane (HFC-254fb), 1,1,1-trifluoropropane (HFC-263fb), 1,1,2-trifluoroethane (HFC-143), hexafluorocyclopropane (cyclo-C ₃ F ₆ ), octafluorocyclobutane (cyclo-C ₄ F ₈ ), cis/trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO-356mff(Z/E)), water, nitrogen, oxygen, CO2, CO and HF. Composition according to Claim 11 or 12, characterized in that it comprises 99.9% by weight, advantageously 99.99% by weight, or even 99.995% by weight of HFC-236ea, at most 190 ppm and at most 0.1 % by weight of HF, preferably at most 10 ppm of water and at most 1 ppm of HF and advantageously at most 1 ppm of water and at most 0.1 ppm of HF.