# US 9,751,768 B2 · Process for extracting phosgene

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- Number: US 9,751,768 B2
- Document ID: US9751768B2
- Status: Granted
- Kind: B2
- Application number: 15/116,252
- Filed: 2015-02-10
- Published: 2017-01-12
- Granted: 2017-09-05
- Earliest claimed: 2014-02-12
- Assignees: Huntsman International LLC
- Applicants: Huntsman International LLC
- Inventors: Rabah Mouazer; Arend-Jan Zeeuw; Robert Henry Carr
- Web page: https://patentgrep.com/patent/US9751768B2

## CPC

- C01B 32/80: Phosgene
- B01D 53/228: {characterised by specific membranes}
- B01D 61/2461: {comprising multiple membrane extraction steps}
- B01D 71/262: {Polypropylene}
- B01D 71/34: Polyvinylidene fluoride
- B01D 71/36: Polytetrafluoroethylene
- C07C 263/10: by reaction of amines with carbonyl halides, e.g. with phosgene
- C07C 263/20: Separation; Purification
- B01D 2257/93: Toxic compounds not provided for in groups B01D2257/00 - B01D2257/708
- B01D 2311/253: Bypassing of feed
- B01D 2315/22: Membrane contactor
- B01D 2325/38: Hydrophobic membranes
- C07C 2601/14: The ring being saturated
- Y02P 20/50: Improvements relating to the production of bulk chemicals
- Y02P 20/582: Recycling of unreacted starting or intermediate materials
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A process for extracting a phosgene compound, comprising providing a membrane extracting unit comprising at least one extracting cell that comprises at least one membrane contactor module having at least two sides, a gas side and a liquid side; letting an initial gas stream comprising a phosgene compound flow on the gas side of the membrane contactor module; and letting an extractant liquid stream, suitable for dissolving a phosgene compound, flow on the liquid side of the membrane contactor module so that the extractant liquid stream absorbs the phosgene compound from the initial gas stream and provides a second extractant liquid stream enriched with the phosgene compound.

## Claims

### Claim 1

A process for extracting a phosgene compound from an initial gas stream, comprising:
providing a membrane contactor module comprising a membrane, which membrane has at least two sides, a gas side and a liquid side;
letting flow an initial gas stream comprising a phosgene compound and a second gas compound selected from the group consisting of hydrogen chloride, carbon monoxide, carbon dioxide, nitrogen, chlorine and a mixture thereof on the gas side of the membrane; and
letting flow an extractant liquid stream, suitable for dissolving the phosgene compound, on the liquid side of the membrane contactor module so that the extractant liquid stream absorbs the phosgene compound from the initial gas stream and provides a second extractant liquid stream enriched with the phosgene compound and wherein a second gas stream depleted in the phosgene compound is provided from the gas side of the membrane and
wherein the phosgene compound is more soluble in the extractant liquid stream than the second gas compound.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the phosgene compound is selected from the group consisting of phosgene (COCl2), bromochlorophosgene (COBrCl), dibromophosgene (COBr2) and a mixture thereof.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the extractant liquid produces a relative volatility α, which is a ratio of K-values [K1/K2], of between 0.02 and 0.08 between the phosgene compound and the second gas compound,
wherein K1 is the concentration of the phosgene compound in the gas phase, divided by the concentration of the phosgene compound in the liquid phase, and
wherein K2 is the concentration of the second gas compound in the gas phase divided by the concentration of the second gas compound in the liquid phase,
when the extractant liquid, the second gas stream and the phosgene compound are in a non dynamic system at 1 bar and at 0° C.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the phosgene compound has a K1 value of between 0.70 and 1.40; and/or
wherein the second gas compound has a K2 value of between 8 and 70; and/or
wherein the extractant liquid has a K3 value of between 0.001 and 0.010, wherein
K
⁢
⁢
3
=
[
extractant
⁢
⁢
liquid
]
⁢
gas
[
extractant
⁢
⁢
liquid
]
⁢
liquid
when the extractant liquid, the second gas stream and the phosgene compound are in a non dynamic system at 1 bar and at 0° C.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the extractant liquid is selected from the group consisting of monochlorobenzene, dichlorobenzene, cyclohexane and toluene.

### Claim 6 (depends on 1)

The process according to claim 1, wherein a pressure is applied across the membrane contractor module such that the pressure at the gas side is higher than the pressure at the liquid side.

### Claim 7 (depends on 6)

The process according to claim 6, wherein the pressure at the gas side is 0.1 to 10 bara more than the pressure at the liquid side.

### Claim 8 (depends on 1)

The process according to claim 1, wherein the membrane contactor module comprises a microporous membrane having a pore size and a thickness such that the phosgene gas goes through the membrane from the gas side to the liquid side, while the extractant remains at the liquid side.

### Claim 9 (depends on 1)

The process according to claim 1, wherein the membrane contactor module comprises a microporous membrane having a pore size and a thickness such that a pressure can be built up at the gas side of the membrane contactor module.

### Claim 10 (depends on 1)

The process according to claim 1, wherein the membrane of the membrane contactor module is polymeric, ceramic, or a composite thereof.

### Claim 11 (depends on 1)

The process according to claim 1, wherein the membrane of the membrane contactor module is hydrophobic and/or is made of polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), silicone rubber, or a combination thereof.

### Claim 12 (depends on 1)

The process according to claim 1, wherein the second gas stream depleted in the phosgene compound is distilled and/or stripped and/or washed with a solvent further reducing the content of the phosgene compound in the second gas stream.

### Claim 13 (depends on 1)

The process according to claim 1, further comprising analyzing the concentrations of the second gas compound, the phosgene compound and/or extractant liquid in the second extractant liquid stream enriched with the phosgene compound and/or in the initial gas stream.

### Claim 14 (depends on 1)

A process for the conversion of an amine to the corresponding isocyanate component by phosgenation of the amine, the process comprising the steps of:
providing a reaction mixture comprising an amine and phosgene to a phosgenation reactor;
at least partially converting the amine and phosgene in the reaction mixture into the corresponding isocyanate component and hydrogen chloride, thereby providing a liquid isocyanate stream comprising the isocyanate component, phosgene and hydrogen chloride;
removing at least part of the phosgene and at least part of the hydrogen chloride from the liquid isocyanate stream as a removed gas stream;
optionally, partially condensing the removed gas stream providing a liquid intermediate mixture and a gas stream coming from the partially condensing step;
optionally, distilling and/or stripping and/or washing with a solvent the gas stream coming from the partially condensing step and/or the liquid intermediate mixture to provide a gaseous vent mixture comprising hydrogen chloride and phosgene;
providing an initial gas stream comprising phosgene and hydrogen chloride, which is the removed gas stream or which is the gas stream coming from the partially condensing step or which is the gaseous vent mixture, or a combination thereof;
extracting phosgene from the initial gas stream according to claim 1, wherein the second gas compound is hydrogen chloride, and providing a second gas stream depleted in phosgene and second extractant liquid stream enriched with the phosgene compound.

### Claim 15 (depends on 14)

The process according to claim 14, wherein the reaction mixture of an amine and phosgene further comprises a solvent selected from the group consisting of monochlorobenzene, dichlorobenzene, cyclohexane and toluene.

### Claim 16 (depends on 15)

The process according to claim 15, wherein the second extractant liquid stream enriched with the phosgene compound is used as a part of the phosgene source in the reaction mixture for at least partially converting the amine and the phosgene compound into the corresponding isocyanate component and hydrogen chloride.

### Claim 17 (depends on 14)

The process according to claim 14, wherein the second extractant liquid stream enriched with the phosgene compound is blended with the liquid intermediate mixture.