# US 11,078,142 B2 · Process and plant for producing methanol from synthesis gases having a high proportion of carbon dioxide

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- Number: US 11,078,142 B2
- Document ID: US11078142B2
- Status: Granted
- Kind: B2
- Application number: 16/996,185
- Filed: 2020-08-18
- Published: 2021-02-25
- Granted: 2021-08-03
- Earliest claimed: 2019-08-19
- Assignees: L'Air Liquide, Societe Anonyme pour I'Etude et I'Exploitation des Procedes Georges Claude
- Applicants: L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude
- Inventors: Bryce Williams; Timm Schuhmann; Veronika Gronemann; Stephane Haag; Frank Castillo-Welter
- Web page: https://patentgrep.com/patent/US11078142B2

## CPC

- C07C 29/1518: {one step being the formation of initial mixture of carbon oxides and hydrogen for synthesis}
- B01J 19/245: {placed in series}
- B01J 19/248: {Reactors comprising multiple separated flow channels}
- B01J 2219/00006: Large-scale industrial plants
- B01J 2219/00033: Continuous processes
- B01J 2219/0004: Processes in series
- C07C 31/04: Methanol
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS

## Abstract

The invention relates to a process for producing methanol and to a plant for producing methanol. A first fresh gas suitable for production of methanol and having a high carbon dioxide content is pre-compressed by a first compressor stage to obtain a second fresh gas. The second fresh gas is merged with a recycle gas stream and further compressed to synthesis pressure in a second compressor stage. Catalytic conversion of the thus obtained synthesis gas stream in a plurality of serially arranged reactor stages with intermediate condensation and separation of the crude methanol reduces the recycle gas amount in the synthesis circuit to such an extent that recycle gas may be directly recycled to the second fresh gas stream, thus ensuring that no recycle gas compressor stage is required and that the total compressor power may be reduced.

## Claims

### Claim 1

A process for producing methanol, comprising:
a) providing an input gas comprising carbon oxides and hydrogen, wherein the proportion of carbon dioxide in the input gas, based on the total amount of the carbon oxides, is at least 80% by volume;
b) introducing the input gas as a first fresh gas stream into a first compressor stage for precompression of the first fresh gas stream to obtain a second fresh gas stream;
c) introducing a recycle gas stream and the second fresh gas stream into a second compressor stage for compression of the recycle gas stream and the second fresh gas stream to synthesis pressure to obtain a synthesis gas stream;
d) catalytically converting the synthesis gas of the synthesis gas stream in a plurality of serially arranged reactor stages at synthesis pressure to obtain a product stream comprising methanol and unreacted synthesis gas per reactor stage;
e) cooling the product stream obtained per reactor stage for condensation and separation of methanol from unreacted synthesis gas and introducing unreacted synthesis gas into a respective subsequent stage of the serially arranged reactor stages;
f) withdrawing unreacted synthesis gas from at least one of the reactor stages as a recycle gas stream for introduction of the recycle gas stream into the second compressor stage according to step c).

### Claim 2 (depends on 1)

The process according to claim 1, wherein after the withdrawing in step f) the recycle gas stream is introduced into the second compressor stage without preceding compression.

### Claim 3 (depends on 1)

The process according to claim 1, wherein according to step e) unreacted synthesis gas is completely introduced into the respective subsequent stage of the serially arranged reactor stages.

### Claim 4 (depends on 1)

The process according to claim 1, wherein according to step f) unreacted synthesis gas is withdrawn as a recycle gas stream from the last of the plurality of serially arranged reactor stages, in particular exclusively withdrawn from the last of the plurality of serially arranged reactor stages.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the recycle gas stream and the second fresh gas stream are merged and introduced into the second compressor stage as a combined gas stream.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the input gas has a stoichiometry number SN of 1.5 to 2.2, wherein
SN
=
n
⁡
(
H
2
)
-
n
⁡
(
CO
2
)
n
⁡
(
CO
)
+
n
⁡
(
CO
2
)
,
with
⁢
⁢
n
⁢
⁢
in
⁢
[
mol
]
.

### Claim 7 (depends on 6)

The process according to claim 6, wherein the input gas has a stoichiometry number SN of 1.5 to 1.9.

### Claim 8 (depends on 1)

The process according to claim 1, wherein a recirculation rate R is defined as
R
=
Volume
⁢
⁢
flow
⁡
(
recycle
⁢
⁢
gas
⁢
⁢
stream
)
Volume
⁢
⁢
flow
⁡
(
second
⁢
⁢
fresh
⁢
⁢
gas
⁢
⁢
stream
)
,
0. 15≤R≤1.25.

### Claim 9 (depends on 8)

process according to claim 8, wherein the recirculation rate R: 0.1≤R ≤0.5.

### Claim 10 (depends on 1)

The process according to claim 1, wherein based on the input gas a carbon dioxide conversion of at least 80 mol % is achieved over the entirety of the plurality of serially arranged reactor stages.

### Claim 11 (depends on 1)

The process according to claim 1, wherein the plurality of serially arranged reactor stages comprises a number of 2 to 8 reactor stages.