# US 9,006,476 B2 · Process for the production of high-purity dimethyl carbonate

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- Number: US 9,006,476 B2
- Document ID: US9006476B2
- Status: Granted
- Kind: B2
- Application number: 13/508,171
- Filed: 2010-10-29
- Published: 2012-11-08
- Granted: 2015-04-14
- Earliest claimed: 2009-11-04
- Assignees: Versalis S.P.A.
- Applicants: Maurizio Ghirardini; Laura De Nardo; Elena Novello
- Inventors: Maurizio Ghirardini; Laura De Nardo; Elena Novello
- Web page: https://patentgrep.com/patent/US9006476B2

## CPC

- C07C 68/08: Purification; Separation; Stabilisation
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

A process for producing a high-purity dimethyl carbonate, which includes: (I) cooling a commercial grade dimethyl carbonate containing 1 ppm or more of chlorine to a temperature from +6° C. to −5° C. at a rate from 0.5-2° C./hour, to obtain a first solid dimethyl carbonate; (II) heating the first solid dimethyl carbonate to a temperature from −5° C. to +6° C. at a rate of 1-5° C./hour, to obtain a mixture comprising a second solid dimethyl carbonate and a predetermined amount of a first liquid dimethyl carbonate; (III) separating the first liquid dimethyl carbonate from the mixture, to obtain the second solid dimethyl carbonate; (IV) heating the second solid dimethyl carbonate to a temperature from 20° C. to 40° C., to obtain a second liquid dimethyl carbonate, wherein the second liquid dimethyl carbonate has a purity degree higher than 99.99% and a chlorine content lower than or equal to 1 ppm.

## Claims

### Claim 1

A process for producing a high-purity dimethyl carbonate, the process comprising:
(I) cooling a commercial grade dimethyl carbonate comprising more than 1 ppm of chlorine by operating a cooling fluid at a cooling temperature ranging from +6° C. to −5° C. at a cooling rate ranging from 0.5° C./hour to 2° C./hour, to obtain a first dimethyl carbonate in solid form;
(II) heating the dimethyl carbonate in solid form, in a first heating, by operating the cooling fluid at a heating temperature ranging from −5° C. to +6° C. at a heating rate ranging from 1° C./hour to 5° C./hour, to obtain a mixture comprising a second dimethyl carbonate in solid form and a predetermined amount of a first dimethyl carbonate in liquid form, wherein the first dimethyl carbonate in liquid form is present in the mixture in an amount ranging from 15% to 30% by weight with respect to a total weight of the commercial grade dimethyl carbonate;
(III) separating the first dimethyl carbonate in liquid form from the mixture, to obtain the second dimethyl carbonate in solid form; and
(IV) heating the second dimethyl carbonate in solid form, in a second heating, by operating the cooling fluid at a heating temperature ranging from 20° C. to 40° C., to obtain a second dimethyl carbonate in liquid form, wherein the second dimethyl carbonate in liquid form has a purity degree higher than 99.99% and a chlorine content lower than or equal to 1 ppm.

### Claim 2 (depends on 1)

The process of claim 1, wherein the commercial grade dimethyl carbonate has a chlorine content in a range from 10 ppm to 100 ppm.

### Claim 3 (depends on 1)

The process of claim 1, wherein the cooling (I) is carried out at a temperature in a range from +5° C. to −3° C. and wherein the heating (II) is carried out at a temperature in a range from −3 C to +5 C.

### Claim 4 (depends on 1)

The process of claim 1, wherein the cooling (I) is carried out at a cooling rate in a range from 0.8° C./hour to 1.5° C./hour.

### Claim 5 (depends on 1)

The process of claim 1, wherein the heating (II) is carried out at a heating rate in a range from 1.5° C./hour to 4° C./hour.

### Claim 6 (depends on 1)

The process of claim 1, wherein the heating (IV) is carried out at a temperature in a range from 25° C. to 35° C.

### Claim 7 (depends on 1)

The process of claim 1, wherein cooling (I) is carried out for a time in a range from 1 hour to 20 hours.

### Claim 8 (depends on 7)

The process of claim 7, wherein the cooling (I) is carried out for a time in a range from 5 hours to 15 hours.

### Claim 9 (depends on 1)

The process of claim 1, wherein the heating (II) is carried out for a time in a range from 2 hours to 10 hours.

### Claim 10 (depends on 9)

The process of claim 9, wherein the heating (II) is carried out for a time in a range from 3 hours to 8 hours.

### Claim 11 (depends on 1)

The process of claim 1, wherein the heating (II) starts before the commercial grade dimethyl carbonate in the cooling (I) has reached a temperature lower than −2° C.

### Claim 12 (depends on 11)

The process of claim 11, wherein the heating (II) starts when the commercial grade dimethyl carbonate in the cooling (I) has reached a temperature in a range from −1.8° C. to −1° C.

### Claim 13 (depends on 1)

The process of claim 1, wherein the first dimethyl carbonate in liquid form is present in the mixture obtained after the heating (II) in an amount in a range from 18% to 25% by weight, with respect to a total weight of the commercial grade dimethyl carbonate.

### Claim 14 (depends on 1)

The process of claim 1, wherein the first dimethyl carbonate in liquid form present in the mixture obtained after the heating (II) has a chlorine content higher than or equal to 4 ppm.

### Claim 15 (depends on 14)

The process of claim 14, wherein the first dimethyl carbonate in liquid form present in the mixture obtained after the heating (II) has a chlorine content in a range from 40 ppm to 500 ppm.