# US 11,691,955 B2 · Process for recovering propylene oxide and carbon dioxide in PPC polyol production

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- Number: US 11,691,955 B2
- Document ID: US11691955B2
- Status: Granted
- Kind: B2
- Application number: 17/460,462
- Filed: 2021-08-30
- Published: 2023-03-02
- Granted: 2023-07-04
- Earliest claimed: 2021-08-30
- Assignees: Saudi Arabian Oil Company
- Applicants: Saudi Arabian Oil Company
- Inventors: ASM Obidullah; Omar Mohammed O AlAmoudi
- Web page: https://patentgrep.com/patent/US11691955B2

## CPC

- C07D 301/32: Separation; Purification
- C08G 65/2603: {the other compounds containing oxygen}
- C08G 64/0208: {saturated}
- C08G 64/34: and cyclic ethers
- C08G 64/403: {Recovery of the polymer}
- C08G 65/2609: {containing aliphatic hydroxyl groups}
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS

## Abstract

In accordance with one or more embodiments of the present disclosure, a process includes introducing a mixture comprising polypropylene carbonate (PPC) polyol, carbon dioxide, propylene oxide, and at least one dibasic ester to a quenching vessel to separate the PPC polyol from the carbon dioxide and the propylene oxide; introducing additional dibasic ester to the separation vessel, thereby separating the carbon dioxide from the propylene oxide and the dibasic ester such that a mixture of propylene oxide and the dibasic ester is formed; and introducing the mixture of propylene oxide and the dibasic ester to a recovery vessel, wherein the propylene oxide is separated from the dibasic ester in the recovery vessel.

## Claims

### Claim 1

A process comprising:
introducing a mixture comprising polypropylene carbonate (PPC) polyol, carbon dioxide, propylene oxide, and at least one dibasic ester to a quenching vessel to separate the PPC polyol from the carbon dioxide and the propylene oxide;
introducing additional dibasic ester to the separation vessel, thereby separating the carbon dioxide from the propylene oxide and the dibasic ester such that a mixture of propylene oxide and the dibasic ester is formed; and
introducing the mixture of propylene oxide and the dibasic ester to a recovery vessel, wherein the propylene oxide is separated from the dibasic ester in the recovery vessel.

### Claim 2 (depends on 1)

The process of claim 1, wherein the at least one dibasic ester is selected from the group consisting of di-methyl adipate, di-methyl glutarate, di-methyl succinate, di-ethyl adipate, diethyl glutarate, di-ethyl succinate, and a combination of two or more thereof.

### Claim 3 (depends on 1)

The process of claim 1, wherein the at least one dibasic ester comprises dimethyl succinate.

### Claim 4 (depends on 1)

The process of claim 1, wherein the at least one dibasic ester is dimethyl succinate.

### Claim 5 (depends on 1)

The process of claim 1, wherein the recovery vessel comprises a distillation column.

### Claim 6 (depends on 1)

The process of claim 1, wherein the recovery vessel comprises at least one distillation column from which the propylene oxide evolves as an overhead product and the dibasic ester evolves as a bottoms product.

### Claim 7 (depends on 1)

The process of claim 1, wherein a source of the mixture comprising carbon dioxide, propylene oxide, and at least one dibasic ester is a reactor.

### Claim 8 (depends on 7)

The process of claim 7, wherein the carbon dioxide from the separation vessel is recycled to the reactor.

### Claim 9 (depends on 1)

The process of claim 1, wherein the carbon dioxide from the separation vessel is vented.

### Claim 10 (depends on 7)

The process of claim 7, wherein the at least one dibasic ester from the recovery vessel is recycled to the reactor.

### Claim 11 (depends on 1)

The process of claim 1, wherein the recovery vessel has a top portion and a bottom portion, the top portion operated at a temperature from 50° C. to 60° C. and a pressure from 1 kPaG to 10 kPaG and the bottom portion operated at a temperature from 220° C. to 230° C. and a pressure from 1 kPaG to 10 kPaG.

### Claim 12 (depends on 1)

The process of claim 1, wherein the recovery vessel has a top portion and a bottom portion, the top portion operated at a temperature from 50° C. to 55° C. and a pressure from 1 kPaG to 10 kPaG and the bottom portion operated at a temperature from 224° C. to 228° C. and a pressure from 1 kPaG to 10 kPaG.