# US 9,868,685 B2 · Processing by a separation technique of a gas mixture formed from a product stream of a dimethyl reactor

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- Number: US 9,868,685 B2
- Document ID: US9868685B2
- Status: Granted
- Kind: B2
- Application number: 15/110,037
- Filed: 2015-01-07
- Published: 2016-11-10
- Granted: 2018-01-16
- Earliest claimed: 2014-01-07
- Assignees: Linde Aktiengesellschaft
- Applicants: Linde Aktiengesellschaft
- Inventors: Helmut Fritz; Andreas Peschel
- Web page: https://patentgrep.com/patent/US9868685B2

## CPC

- C07C 41/42: by distillation
- B01D 3/143: {by two or more of a fractionation, separation or rectification step}
- B01D 5/0036: {Multiple-effect condensation; Fractional condensation}
- B01D 53/1431: {Pretreatment by other processes}
- B01D 53/1493: {Selection of liquid materials for use as absorbents}
- C07C 41/01: Preparation of ethers
- C07C 41/38: by liquid-liquid treatment
- B01D 2257/108: Hydrogen
- B01D 2257/502: Carbon monoxide
- B01D 2257/504: Carbon dioxide
- Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2
- Y02P 70/10: Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- 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)
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method for the processing, by separation technology, of a gas mixture (k) which is formed from a product stream (d) of a reactor (4) for synthesizing dimethyl ether from synthesis gas (b), and which contains at least dimethyl ether, carbon dioxide and at least one other component which is lower-boiling than carbon dioxide, is proposed. The gas mixture (k) is cooled at a first pressure level from a first temperature level to a second temperature level and a fraction of the gas mixture (k) that remains in gaseous form at the second temperature level is washed in an absorption column (16) with a reflux (v) predominantly containing carbon dioxide. The reflux (v) predominantly containing carbon dioxide is at least partially formed from a fraction of the gas mixture (k) which is separated in liquid form during the cooling.

## Claims

### Claim 1

Method for the processing, by separation technology, of a gas mixture (k) which is formed from a product stream (d) of a reactor (4) for synthesising dimethyl ether from synthesis gas (b), and which contains at least dimethyl ether, carbon dioxide and at least one other component which is lower-boiling than carbon dioxide, characterised in that the gas mixture (k) at a first pressure level is cooled from a first temperature level to a second temperature level and a fraction of the gas mixture (k) that remains in gaseous form at the second temperature level is washed in an absorption column (16) with a reflux (v) predominantly containing carbon dioxide, the reflux (v) predominantly containing carbon dioxide being at least partially formed from a fraction of the gas mixture (k) which is separated in liquid form during the cooling.

### Claim 2 (depends on 1)

Method according to claim 1, wherein the gas mixture (k) is cooled through several intermediate temperature levels to the second temperature level, in the course of which a plurality of condensates (l, q, r) are separated.

### Claim 3 (depends on 1)

Method according to claim 1, wherein the fraction of the gas mixture (k) remaining in gaseous form at the second temperature level is washed in an absorption column (16) with the reflux (v) predominantly containing carbon dioxide, in the course of which a top product (x) and a sump product (w) are recovered, the reflux (v) which predominantly contains carbon dioxide being formed partially from the sump product (w).

### Claim 4 (depends on 1)

Method according to claim 1, wherein the reflux (v) predominantly containing carbon dioxide is formed using a dimethyl ether/carbon dioxide distillation column (9).

### Claim 5 (depends on 4)

Method according to claim 4, wherein the dimethyl ether/carbon dioxide distillation column (9) is operated such that at its top is formed a top gas (t) predominantly containing carbon dioxide and in its sump is formed a sump liquid rich in dimethyl ether.

### Claim 6 (depends on 5)

Method according to claim 5, wherein part of a condensate which is formed from at least part of the top gas of the dimethyl ether/carbon dioxide distillation column (9) is used as the reflux (v) predominantly containing carbon dioxide.

### Claim 7 (depends on 5)

Method according to claim 5, wherein at least some of the sump liquid of the dimethyl ether/carbon dioxide distillation column (9) is drawn off as a product stream (z) which has a dimethyl ether content of more than 90 mol %.

### Claim 8 (depends on 4)

Method according to claim 4, wherein the dimethyl ether/carbon dioxide distillation column (9) is operated at a second pressure level which is below the first pressure level.

### Claim 9 (depends on 1)

Method according to claim 1, wherein the reflux predominantly containing carbon dioxide has a dimethyl ether content of not more than 10 mol %.

### Claim 10 (depends on 1)

Method according to claim 1, wherein the gas mixture (k) is formed by at least partially removing methanol and/or water from the product stream (d).

### Claim 11 (depends on 1)

Method according to claim 1, wherein the first temperature level is 20 to 50° C., and wherein the second temperature level is between the melting temperature of carbon dioxide at the pressure level used and −15° C.

### Claim 12 (depends on 1)

Method according to claim 1, wherein the first pressure level is 20 to 100 bar.