DESC:FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

A PROCESS FOR PURIFICATION POLYHALOPROPENES

SRF LIMITED, AN INDIAN COMPANY,
SECTOR 45, BLOCK-C, UNICREST BUILDING,
GURGAON – 122003,
HARYANA (INDIA)

The following specification particularly describes the invention and the manner in which it is to be performed.
FIELD OF THE INVENTION
The present invention provides a process for purification of polyhalopropenes.

BACKGROUND OF THE INVENTION
Polyhalopropenes, particularly, tetrafluoropropenes have found widespread use in many commercial and industrial applications including as refrigerants, aerosol propellants, blowing agents, heat transfer media, gaseous dielectrics and as working fluids in air conditioning, heat pump and refrigeration systems.
The manufacturing processes of polyhalopropenes commonly results in one or more undesired alkyne compounds, such as preparation of tetrafluoropropene results in one or more undesired (hydro)fluoroalkyne compounds, such as 3,3,3-trifluoropropene alongside a desired tetrafluoropropene, therefore necessitating purification.
US Patent No. 9309176 provides a process for removing one or more undesired (hydro)halocarbon compounds from a (hydro)fluoroalkene, the process comprising contacting a composition comprising the (hydro)fluoroalkene and one or more undesired (hydro)halocarbon compounds with an aluminum-containing absorbent, activated carbon, or a mixture thereof.
US patent No. 9272968 provides a process for removing 3,3,3-trifluoropropyne using water and sulphuric acid.
European patent No. 3412647 provides a process for removing 3,3,3-trifluoropropyne using zeolite having pore size of at least 4 Angstroms and no more than 5 Angstroms.
US patent No. 10633312 provides a process for removing 3,3,3-trifluoropropyne using zeolite having pore size of at least 4 Angstroms and no more than 6 Angstroms.
US patent No. 11358919 provides a process for reducing 3,3,3-trifluoropropyne using a basic solution comprising a hydroxide, an alkoxide and/or an amide.
The present invention provides an alternative process for purification of polyhalopropenes to obtain polyhalopropenes of very high purity.

OBJECT OF THE INVENTION
The object of the present invention is to provide a simple, cost effective and commercially viable process for purification of polyhalopropenes.

SUMMARY OF THE INVENTION
In an aspect, the present invention provides a process for purification of polyhalopropene, comprising the steps of:
a) providing a composition comprising polyhalopropene and one or more undesired (hydro)fluoroalkyne compounds, in a distillation column;
b) maintaining a high reflux ratio in the range of 5 to 100 at the head of the distillation column;
c) allowing removal of a fraction of low boiling components from the top of distillation column; or allowing low boiling components to get enriched at the top and ensuring no low boiling components remain at the bottom.
d) repeating step b) and c) till the low boiling component become substantially nil; and/or the material at the bottom can be taken to another distillation column from where product free of these impurities can be removed from the top.
e) distilling the remaining composition in distillation column to separate pure polyhalopropene from the top of distillation column by maintaining a reflux ratio in the range of 5 to 100.

BRIEF DESCRIPTION OF DRAWING
Figure 1 and Figure 2 describes the flow of the process.
Figure 1: A stream ‘1’ is charged in a distillation column ‘D1’ and allowed venting of non-condensable components ‘2’ through metering valve ‘V1’. After removal of ‘2’, total reflux is maintained for 2 hours in ‘D1’ and allowed removal of a fraction of low boiling components ‘3’ from the top through condenser ‘C1’ and metering valve ‘V1’. The draw rate of ‘3’ is maintained using the mass flow meters ‘MFM-1 and MFM-3’, so that the reflux ratio is 10. The total reflux is maintained again for 2 hours in ‘D1’ and allowed removal of another fraction of ‘3’ from the top. The total reflux is maintained again for 2 hours in ‘D1’ and allowed removal of remaining fraction of ‘3’ from the top. The remaining mixture in ‘D1’ is distilled to obtain polyhalopropene ‘4’ from the top and high boiling components ‘5’ are removed from the bottom re-boiler ‘RB1’ passing from ‘MFM-2’.
Figure 2: A stream ‘1’ is charged in a distillation column ‘D1’ and allowed venting of non-condensable components ‘2’ through metering valve ‘V1’. After removal of ‘2’, total reflux is maintained for 2 hours in ‘D1’ and allowed removal of a fraction of low boiling components ‘3’ from the top through ‘C1’ and ‘V1’. The draw rate of ‘3’ is maintained using the mass flow meters ‘MFM-1 and MFM-3’ respectively, so that the reflux ratio is 10. The total reflux is maintained again for 2 hours in ‘D1’ and allowed removal of another fraction of ‘3’ from the top. The total reflux is maintained again for 2 hours in ‘D1’ and allowed removal of remaining fraction of ‘3’ from the top. The Bottom material of the column is made free of low boiling components which comes from top of column D-1. The remaining mixture in re-boiler ‘RB1’ of distillation column ‘D1’ is charged into re-boiler ‘RB2’ of distillation column ‘D2’ controlled via ‘MFM-2’ and distilled to obtain pure polyhalopropene ‘4’ from the top of ‘D2’ through condenser ‘C2’ and metering valve ‘V2’ and mass flow meter ‘MFM-5’. The reflux ratio in “D2’ is maintained using MFM-4 and high boiling components ‘5’ are removed from the bottom of ‘D2’ through ‘MFM-6’.

DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term polyhalopropenes include 1,1,1,3-tetrafuoropropene (1234ze-E and 1234ze-Z); 2,3,3,3-tetrafluoropropene (1234yf); 3,3,3-Trifluoropropene (1243zf); 2-chloro-3,3,3-trifluoropropene (1233xf), 1-chloro-3,3,3-trifluoropropene (1233zd-Z and 1233zd-E), 1-chloro-1,3,3,3-tetrafluoropropene, 1,1,3,3,3-pentafluoropropene (1225zc), 2-chloro-1,3,3,3-tetrafluoropropene, 1,2,3,3,3-pentfluoropropene (1225ye), 1,1-dichloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3-trifluoropropene, 1-chloro-2,3,3,3-tetrafluoropropene (1224yd), 1,1,2,3,3-pentafluoropropene, 1-chloro-2,3,3-trifluoropropene (1233yd) or the like.
As used herein, the term undesired (hydro)fluoroalkyne compounds refers to 3,3,3-trifluoropropyne (CF3C=CH).
In an embodiment, the purity of polyhalopropene ranges from at least 99.95%. The various terms used in Figures 1 & 2 are as described below.
As used herein, stream ‘1’ refers to a crude mixture of polyhalopropene, non-condensable, low boiling and high boiling components.
As used herein, ‘2’ refers to non-condensable components.
As used herein, ‘3’ refers to low boiling components.
As used herein, ‘4’ refers to pure polyhalopropene.
As used herein, ‘5’ refers to high boiling components.
As used herein, ‘D1’ refers to first distillation column and ‘D2’ refers to second distillation column.
As used herein, ‘C1’ refers to first condenser and ‘C2’ refers to second condenser.
As used herein, ‘V1’ refers to first metering valve and ‘V2’ refers to second metering valve.
As used herein, ‘RB1’ refers to first re-boiler and ‘RB2’ refers to second re-boiler.
As used herein, ‘MFM-1’, ‘MFM-2’, ‘MFM-3’, ‘MFM-4’, ‘MFM-5’ and ‘MFM-6’ refers to first, second, third, fourth, fifth and sixth mass flow meters respectively.
As used herein, the substantially nil amount refers 5-100 ppm of that component, when analyzed by GC-MS analysis.
As used herein, the low boiling component refers to a component having boiling point, ranging from about -70 to -35°C. The low boiling component may refer to 3,3,3-trifluoropropyne and may also include the components selected from a group consisting of pentafluoroethane(-48?) and chlorodifluoromethane (-40?).
As used hereinabove, the high boiling component refers to a component having boiling point in the range from about -30 to 80°C. The high boiling component is selected from a group consisting of 1,1,1,3,3,3-hexafluoro propane (HFC-236fa); 1,3,3,3-tetrafluoroprop-1-ene (1234ze-E and 1234ze-Z); 3,3,3-trifluoropropene; 1,2,3,3,3-pentafluoropropene (Z and E); 1,1-dichloro-1,2,2,2-tetrafluoroethane (CFC-114a); 1,2-dichloro-1,1,2,2-tetrafluoroethane (CFC-114); 1-chloro-1,1,2,2-tetrafluoroethane (CFC-124a); 2-chloro-1,1,1,2-tetrafluoroethane (CFC-124); vinyl chloride (VCM); 1-chloro-3,3,3-trifluoropropene (E and Z); methylene chloride (HCC-30); 1,1-dichloroethane; carbontetrachloride; 1,2-dichloroethane (HCC 150).
In an embodiment, the preferred polyhalopropene is selected from 1,1,1,3-tetrafuoropropene (1234ze); 2,3,3,3-tetrafluoropropene (1234yf); 1-chloro-1,3,3,3-tetrafluoropropene, 1,1,3,3,3-pentafluoropropene (1225ye), 1,2,3,3,3-pentfluoroprope (1225ye), 1,1-dichloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3-trifluoropropene, 1-chloro-2,3,3,3-tetrafluoropropene (1224yd).
The composition of polyhalopropene to be purified may additionally contains one or more of non-condensable components.
As used herein, the non-condensable components have very low boiling point of less than -80°C or range from -170 to -80°C and are selected from a group consisting of acetylene, nitrogen, air or the like.
In an embodiment, the non-condensable impurities having very low boiling point are removed at the top of distillation column before high reflux is maintained. After removal of non-condensable impurities, the high reflux is maintained to enrich low boiling components at the top of distillation column and thus removed from the top. After the complete removal of low boiling component, the remaining mixture is distilled to enrich pure polyhalopropene at the top and thus is isolated from the top of distillation column. The remaining high boiling component is separated from the bottom of distillation column.
As used herein, the reflux ratio refers to L/V ratio, wherein L is the flow rate of the liquid in Kg/hour and V is the flow rate of the vapor in Kg/hour. In other words, the reflux ratio is the ratio of amount of liquid returning in distillation column to the liquid removed from the column.
As used herein, the total reflux ratio refers reflux ratio when nothing is withdrawn from the column. In other words, the total reflux ratio refers to L/V ratio = 8, wherein L is the flow rate of the liquid in Kg/hour and V is the flow rate of the vapor in Kg/hour.
In an embodiment, the process is carried out while maintaining a total reflux ratio for some time prior to maintaining high reflux ratio.
In an embodiment, the high reflux is achieved by maintaining reflux ratio in the range of from 5-100. In a preferred embodiment, the high reflux is achieved by maintaining reflux ratio in the range of from 10-50. In other words, the high reflux ratio means that more liquid that has returned to the distillation column compared to the amount of liquid removed. The reflux ratio is measured through mass flow metres which is placed in reflux line and another in product removal line.
In an embodiment, the total reflux, the high reflux, and distillation steps are carried out in a single distillation column or sequential distillation columns.
In another embodiment, the high reflux and distillation steps are carried out in a separate distillation column connected to each other.
In an embodiment, the distillation may be carried out in a continuous distillation column or a batch distillation column.
In an embodiment, the distillation is carried out in a batch mode as shown in Figure 1.
In an embodiment, the distillation is carried out continuously in two distillation columns connected to each other in series for sequential separation of non-condensable components, low boiling components and high boiling components as given in Figure 2.
In another embodiment, the distillation may also be carried out continuously in multiple distillation column connected to each other in series for sequential separation of non-condensable components, low boiling components and high boiling components.
The composition feed which is subjected to purification in the present invention comprises the following composition. The analysis was carried out in GCMS.
In an embodiment, polyhalopropene is obtained with a purity greater than 99.99%, having low boiling component less than 100 ppm preferably between 10 to 100 ppm and high boiling components less than 100 ppm, preferably between 10 to 100 ppm.
In an embodiment, tetrafluoropropene is obtained with a purity greater than 99.99%, having low boiling component less than 100 ppm preferably between 10 to 100 ppm and high boiling components less than 100 ppm, preferably between 10 to 100 ppm.
In another embodiment, tetrafluoropropene obtained by the process of present invention has purity of 99.99% to 99.999% having total content of low and high boiling components of less than 100 ppm, preferably 10 to 100 ppm.
In an embodiment, the pure polyhalopropene contains substantially nil amount of non-condensable components.
In an embodiment, the pure tetrafluoropropene contains substantially nil amount of non-condensable components.
In an embodiment, the pure polyhalopropene contains substantially nil amount of any other impurity component.
In another embodiment, the low boiling components are removed at a rate of 10g/hr to 500g/hr from the top of distillation column through metered valve.
In a specific embodiment, the low boiling components are removed at a rate of 15g/hr to 300g/hr from the top of distillation column through metered valve.
In another embodiment, the reflux ratio is measured at the head of the distillation column. The high reflux ratio enables enrichment of low boiling components, which can be later withdrawn in small portions. In a smaller scale, the low boilers can be enriched by maintaining total reflux for certain specific time and then withdrawing a small portion.
In another embodiment of the present invention, the distillation column is maintained at a temperature gradient of 1 to 5°C. The temperature gradient is the difference in the temperature of the top and the bottom of the distillation column.
In another embodiment of the present invention the process is carried out as illustrated in Figure 1.
In another embodiment of the present invention, the process is carried out as illustrated in Figure 2.
The pure product i.e., polyhalopropene is monitored by gas chromatography (GC).
Unless stated to the contrary, any of the words “comprising”, “comprises” and includes mean “including without limitation” and shall not be construed to limit any general statement that it follows to the specific or similar items or matters immediately following it.
Embodiments of the invention are not mutually exclusive but may be implemented in various combinations. The described embodiments of the invention and the disclosed examples are given for the purpose of illustration rather than limitation of the invention as set forth in the appended claims.
The crude trans-1,3,3,3-tetrafluoropropene as used herein as composition feed can be prepared by any of the methods known in the art.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.

EXAMPLES 1:
Inlet feed (10 Kg) was taken for distillation and feed composition is given below:
S.No. Compound Composition %
1 R-1234ze 99.7897
2 Trifluoropropyne 0.0011
3 R-152a 0.1526

After charging the material, non-condensable was vented out and then the column was under reflux for two hours. Then we took sample (100g) with below composition:
S.No. Compound Composition %
1 R-1234ze 96.5530
2 Trifluoropropyne 0.0825
3 R-152a 2.1450

The light components got enriched in this cut.
After removing top cut material (500 g) while maintain reflux ratio of 10, and analysed, the composition is given below:
S.No. Compound Composition %
1 R-1234ze 99.9321
2 Trifluoropropyne Not detected
3 R-152a 0.0484

Example 2-5: Result are given in below table.
Ex. No Composition Initial Conc. Conc. after non-condensable removal Final conc.
2 R-1234yf 99.7897 96.5530 99.9321
Trifluoropropyne 0.0011 0.0825 Not detected
R-152a 0.1526 2.1450 0.0484
3 R-1225zc 99.7907 96.5630 99.9409
Trifluoropropyne 0.0013 0.0821 Not detected
R-152a 0.1520 2.1450 0.0475
4 R-1225ye 99.7301 96.8610 99.9328
Trifluoropropyne 0.0014 0.0828 Not detected
R-152a 0.1519 2.1560 0.0445
5 R-1224yd 99.7813 96.5330 99.9421
Trifluoropropyne 0.0014 0.0835 Not detected
R-152a 0.1526 2.1450 0.0484

Dated this 18th Day of December 2024.

,CLAIMS:1. A process for purifying polyhalopropene, comprising the steps of:
a) providing a composition comprising polyhalopropene and one or more undesired (hydro)fluoroalkyne compounds, in a distillation column;
b) maintaining a high reflux ratio in the range of 5 to 100 at the head of the distillation column;
c) allowing removal of a fraction of low boiling components from the top of distillation column; or allowing this low boiling components to get enriched at the top and ensuring no low boiling components remain at the bottom;
d) repeating step b) and c) till the low boiling component become substantially nil; and/or the material at the bottom can be taken to another distillation column from where product free of these impurities can be removed from the top;
e) distilling the remaining composition in distillation column to separate pure polyhalopropene from the top of distillation column by maintaining a reflux ratio in the range of 5 to 100.
3. The process as claimed in claim 1, wherein the undesired (hydro)fluoroalkyne is 3,3,3-trifluoropropyne (CF3C=CH).
4. The process as claimed in claim 1, wherein the step b) of maintaining a high reflux ratio in the range of 5 to 100 at the head of the distillation column and step c) of allowing removal of a fraction of low boiling components from the top of distillation column are repeated at least twice.
5. The process as claimed in claim 1, wherein the distillation column is maintained at a temperature gradient of 1 to 5°C.
6. The process as claimed in claim 1, wherein the low boiling components are removed at a rate of 10g/hr to 500g/hr from the top of distillation column through metered valve.
7. The process as claimed in claim 1, wherein the distillation is carried out in a continuous distillation column or batch distillation column.
8. The process as claimed in claim 7, wherein the continuous distillation is carried out continuously in multiple distillation columns connected to each other for sequential separation of non-condensable components, low boiling components and high boiling components.
9. The process as claimed in claim 1, wherein the polyhalopropene is obtained with a purity greater than 99.99% and having low boiling component less than 100 and high boiling components less than 100 ppm.
10. The process as claimed in claim 1, wherein the flow of the process is as illustrated in Figure 1 and Figure 2.
Dated this 18th Day of December 2024.

SRF LIMITED NO. OF SHEETS: 02
APPLICATION NO. IN202311086660A SHEET NO. 01

Figure 1

Dated this 18th Day of December 2024.

SRF LIMITED NO. OF SHEETS: 02
APPLICATION NO: IN202311086660A SHEET NO. 02

Figure 2

Dated this 18th Day of December 2023.