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

“PROCESS FOR REMOVAL OF WATER FROM FLUOROCARBONS”

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

The following specification particular describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention provides a process for removal of moisture from a gas stream containing fluorocarbons.

BACKGROUND OF THE INVENTION
Fluorocarbons are important compounds that find applications as heat transfer agents, refrigerants, foaming agents, solvents, cleaning agents, propellants, and fire extinguishers.
Generally, fluorocarbons are produced by fluorination that either uses or generates hydrogen fluoride, which is normally removed by passing the product stream through water or aqueous sulfuric acid or alkali solution that results in significant amount of water in fluorocarbon. Various methods are known in the literature for removal of water from the fluorocarbons.
European Patent Publication No. 2566929 discloses a method for isolating trans-1,3,3,3-tetrafluoropropene from an azeotropic mixture containing trans-1,3,3,3-tetrafluoropropene and water by distillation and liquid-liquid separation followed by treatment with drying agents such as molecular sieves, silica, and alumina etc.
US Patent Publication No. 20140256995 discloses a process for removal of water using desiccants that includes silica gel, activated charcoal, calcium sulfate, calcium chloride, montmorillonite clay, and various molecular sieves.
US Patent No. 1,116,8044 discloses a process for drying the composition of fluorocarbon using a solid absorbent such as magnesium sulfate, calcium sulfate, calcium chloride or may be molecular sieves of 3Å , 4Å , 5Å , AW500, XH-7, XH-9 or 13X type, silica gel, and active charcoal or a mixture thereof.
European Patent Publication No. 3325437 discloses a method of drying hydro(chloro)fluoroolefins by contacting it with a source of sulphuric acid.

US Patent No. 1,063,3312 discloses a method of drying hydrofluoroolefin by passing the stream through an adsorbent comprising zeolites of type A having a pore diameter ranging from 3 Å to 6 Å.
US Patent Publication No. 20220169816 discloses a method of removing water from the fluorocarbon using azeotropic distillation followed by a phase separation, further distillation, or fractionation.
PCT Publication No. 2021090071 discloses a method of removing water from the fluorocarbon using azeotropic distillation followed by phase separation, further distillation, or fractionation and treatment with a desiccant.

OBJECT OF THE INVENTION
The main object of the present invention is to provide a cost effective and commercially viable process for removal of water from a gas stream containing fluorocarbons.

SUMMARY OF THE INVENTION
The present invention provides a process for removal of water from a gas stream containing fluorocarbon, comprising a step of contacting the gas stream with polyhydric alcohols.

DETAILED DESCRIPTION OF THE INVENTION
As used herein, fluorocarbon is selected from a group consisting of fluoroalkanes and fluoroolefins, or the like. Examples of fluoroalkanes include difluoromethane (R32), chlorodifluoromethane (R22), monofluoroethane (R161), difluoroethane (R152a), chlorodifluoroethane (R142a, R142b), trifluoroethane (R143a, R143b), tetrafluoroethane (R134, R134a), pentafluoroethane (R125), hexafluoroethane, monofluoropropane, difluoropropane, trifluoropropane, chlorotetrafluroopropane (R244cb, R244bb), tetrafluoropropane (R254cb), pentafluoropropane (R245fa, R245ca), and hexafluoropropane or the like. Examples of fluoroolefins include difluoroethylene, trifluoroethylene, 1,1,1,2-tetrafluroopropene, 1,3,3,3-tetrafluoropropene, 2-chloro-3,3,3-trifluoropropene, 1-chloro-3,3,3-trifluoropropene, tetrafluorobutene, and hexafluorobutene (r1336mzz), or the like.
As used herein, the fluorocarbon may be a mixture of different fluoroalkane and fluoroolefins.
As used herein, the polyhydric alcohol is selected from a group consisting of ethylene glycol, propylene glycol, isopropylene glycol, glycerol, diethylglycol, and triethylglycol or the like.
As used herein, the outlet gas stream refers to the gas stream obtained after passing inlet gas stream through metal salt. The outlet gas stream may contain water in the range from 0.00001 to 1%.
As used herein, the inlet gas stream refers to the product stream containing fluorocarbon and water. The inlet gas stream may contain water in the range from 0.1-10%.
The outlet stream may contain some content of water and can be passed through a series of polyhydric alcohol absorber till the amount of water reaches <0.0010% complete removal of water may require 2-5 absorption cycles.
In an embodiment of the present invention, the inlet gas stream is contacted with polyhydric alcohol at a temperature range of -10 to 50°C and more preferably at a temperature of 0-40°C.
In an embodiment, the present invention provides a process for removing water from a gas stream, comprising the steps of contacting an inlet gas stream comprising water and fluorocarbon with a polyhydric alcohol to obtain an outlet gas stream free of water.
The outlet gas stream is considerably free of moisture and contains water in the range from 0.00001 to 0.005%.
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 following example is given by way of illustration and therefore should not be construed to limit the scope of the present invention.

EXAMPLES
Example 1: Removal of water from a mixture of 1234yf and water
A gas stream comprising 1234yf and 5% of water was contacted with ethylene glycol at 30°C to obtain outlet stream of 1234yf containing 0.0010% of water.
Example 2: Removal of water from a mixture of 1234ze and water
A gas stream comprising 1234ze and 5% of water was contacted with glycerol at 30°C to obtain outlet stream of 1234ze containing 0.0010-0.0015% of water.
Example 3: Removal of water from a mixture of 1233zd and water
A gas stream comprising 1233zd and 5% of water was contacted with isopropylene glycol at 30°C to obtain outlet stream of 1233zd containing 0.001-0.0012% of water.
Example 4: Removal of water from a mixture of R32 and water
A gas stream comprising R32 and 2% of water was contacted with isopropylene glycol at 30°C to obtain outlet stream of R32 containing 0.001-0.0012% of water.

Example 5: Removal of water from a mixture of R134a and water
A gas stream comprising R134a and 3.5% of water was contacted with isopropylene glycol at 30°C to obtain outlet stream of 134a containing 0.001-0.0012% of water.

,CLAIMS:WE CLAIM
1. A process for removal of water from a gas stream containing fluorocarbon, comprising a step of contacting the gas stream with polyhydric alcohols.
2. The process as claimed in claim 1, wherein the fluorocarbon is selected from a group consisting of fluoroalkanes and fluoroolefins or a mixture thereof.
3. The process as claimed in claim 1, wherein the polyhydric alcohol is selected from a group consisting of ethylene glycol, propylene glycol, isopropylene glycol, glycerol, diethylglycol, and triethylglycol.
4. The process as claimed in claim 1, wherein the gas stream includes outlet gas stream and inlet gas stream.
5. The process as claimed in claim 4, wherein the outlet gas stream refers to the gas stream obtained after passing inlet gas stream through metal salt. The outlet gas stream may contain water in the range from 0.00001 to 1%.
6. The process as claimed in claim 4, wherein the inlet gas stream refers to the product stream containing fluorocarbon and water. The inlet gas stream may contain water in the range from 0.1-10%.
7. The process as claimed in claim 6, wherein the inlet gas stream is contacted with polyhydric alcohol at a temperature range of -10 to 50°C.
8. The process as claimed in aforesaid claims, wherein the outlet gas stream is considerably free of moisture or contains water in the range from 0.00001 to 0.005%.

9. The process as claimed in claim 1, wherein the outlet stream is passed through a series of polyhydric alcohol absorber till the amount of water reaches <0.0010% or become considerably nil.

Dated this 05th day of September 2022.