Methods for removal of sulfur dioxide (SO

Inventors: Haluk Kopkalli (Staten Island, NY); Haiyou Wang (Amherst, NY); Terris Yang (East Amherst, NY); Jennifer W. McClaine (Branchburg, NJ); Richard Wilcox (West Caldwell, NJ); Joshua Close (Cheektowaga, NY); Rajendar Mallepally (Charlotte, NC)

Assignee: Solstice Advanced Materials, US Inc.

C07C71/00 B01D3/36 B01D53/02 B01J20/18 C07C51/64 C07C53/48 B01D2253/108

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Quick Facts

Patent No.: US 12679800
App. No.: 18/636,199
Granted: Jul 14, 2026
Kind: B2

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Abstract

Impurities such as sulfur dioxide (SO 2 ) are removed from trifluoroacetyl chloride (TFAC) through distillation, adsorption, or a combination thereof, and/or including the formation of an azeotrope or azeotrope-like composition including effective amounts of sulfur dioxide (SO 2 ) and trifluoroacetyl chloride (TFAC). The trifluoroacetyl chloride (TFAC) thus purified may then be used in the manufacture of trifluoroiodomethane (CF 3 I). Also disclosed are azeotropes and azeotrope like compositions of sulfur dioxide (SO 2 ) and trifluoroacetyl chloride (TFAC).

Claims (31)

1 . A method of removing sulfur dioxide (SO 2 ) as an impurity in a process for producing trifluoroacetyl iodide (TFAI), the method comprising:

reacting a reactant stream comprising trifluoroacetyl chloride (TFAC), hydrogen iodide (HI), and sulfur dioxide (SO 2 ) to produce a stream comprising trifluoroacetyl iodide (TFAI) and hydrogen chloride (HCI), along with unreacted trifluoroacetyl chloride (TFAC) and hydrogen iodide (HI), and sulfur dioxide (SO 2 );

distilling the stream;

recovering a first overhead stream comprising hydrogen chloride (HCl), trifluoroacetyl chloride (TFAC), sulfur dioxide (SO 2 ), and hydrogen iodide (HI);

recovering a first bottoms product comprising TFAI; and

conveying, at least one of before and after the distilling step, the stream through an adsorption column to reduce an amount of the sulfur dioxide (SO 2 ) in the stream.

2 . The method of claim 1 , wherein the conveying step occurs after the reacting step and prior to the distilling step.

3 . The method of claim 1 , wherein the adsorption column comprises one or more of molecular sieves, carbon molecular sieves, zeolite powder, silica gel, activated alumina, activated carbon, and combinations of the foregoing.

4 . The method of claim 3 , wherein the adsorption column comprises carbon molecular sieves.

5 . The method of claim 1 , wherein the conveying step occurs after the distilling step.

6 . The method of claim 1 , further comprising reacting the TFAI to form trifluoroiodomethane (CF 3 I).

7 . The method of claim 1 , further comprising:

distilling the first overhead stream comprising hydrogen chloride (HCl), trifluoroacetyl chloride (TFAC), sulfur dioxide (SO 2 ), and hydrogen iodide (HI) to provide a second overhead stream comprising hydrogen chloride (HCl) and a second bottoms product comprising trifluoroacetyl chloride (TFAC), sulfur dioxide (SO 2 ), and hydrogen iodide (HI).

8 . The method of claim 7 , further comprising feeding trifluoroacetyl chloride (TFAC) to the reacting step via a recycle stream.

9 . The method of claim 8 , wherein a concentration of sulfur dioxide (SO 2 ) in the recycle stream is less than 50 ppm.

10 . The method of claim 8 , wherein a concentration of sulfur dioxide (SO 2 ) in the recycle stream is less than 10 ppm.

11 . The method of claim 7 , further comprising conveying the second bottoms product through an adsorption column to reduce an amount of the sulfur dioxide (SO 2 ) in the second bottoms product.

12 . A method of removing sulfur dioxide (SO 2 ) as an impurity in a process for producing trifluoroacetyl iodide (TFAI), the method comprising:

reacting a reactant stream comprising trifluoroacetyl chloride (TFAC), hydrogen iodide (HI), and sulfur dioxide (SO 2 ) to produce a product stream comprising trifluoroacetyl iodide (TFAI) and hydrogen chloride (HCl), along with unreacted trifluoroacetyl chloride (TFAC) and hydrogen iodide (HI), and sulfur dioxide (SO 2 ); and

conveying the product stream through an adsorption column to reduce an amount of the sulfur dioxide (SO 2 ) in the product stream.

13 . The method of claim 12 , further comprising the additional steps of:

distilling the product stream;

recovering a first overhead stream comprising hydrogen chloride (HCl), trifluoroacetyl chloride (TFAC), sulfur dioxide (SO 2 ), and hydrogen iodide (HI); and

recovering a first bottoms product comprising TFAI; and

14 . The method of claim 13 , wherein the conveying step precedes the distilling step.

15 . The method of claim 13 , wherein the conveying step follows the distilling step.

16 . The method of claim 12 , further comprising feeding trifluoroacetyl chloride (TFAC) to the reacting step via a recycle stream.

17 . The method of claim 16 , wherein a concentration of sulfur dioxide (SO 2 ) in the recycle stream is less than 50 ppm.

18 . The method of claim 16 , wherein a concentration of sulfur dioxide (SO 2 ) in the recycle stream is less than 10 ppm.

19 . The method of claim 13 , further comprising reacting the TFAI to form trifluoroiodomethane (CF 3 I).