# US 2023/0264145 A1 · Improving the purity of a CO2-rich stream

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- Number: US 2023/0264145 A1
- Document ID: US20230264145A1
- Status: Published application
- Kind: A1
- Application number: 18/006,929
- Filed: 2021-09-20
- Published: 2023-08-24
- Earliest claimed: 2020-09-21
- Assignees: Topsoe A/S
- Applicants: Topsoe A/S
- Inventors: Per Juul DAHL; Morten GHILADI; Arunabh SAHAI; Johannes SKOTTE
- Web page: https://patentgrep.com/patent/US20230264145A1

## CPC

- B01D 53/75: Multi-step processes
- B01D 53/82: with stationary reactants
- B01D 53/1425: {Regeneration of liquid absorbents}
- B01D 53/1475: {Removing carbon dioxide}
- B01D 53/265: {by refrigeration (condensation)}
- B01D 53/864: {Removing carbon monoxide or hydrocarbons}
- C01B 3/36: using oxygen; using mixtures containing oxygen as gasifying agents
- C01B 3/48: followed by reaction of water vapour with carbon monoxide
- C01B 3/52: by contacting with liquids; Regeneration of used liquids
- C01B 32/50: Carbon dioxide
- B01D 2251/102: Oxygen
- B01D 2256/16: Hydrogen
- B01D 2256/22: Carbon dioxide
- B01D 2257/502: Carbon monoxide
- B01D 2257/702: Hydrocarbons
- B01D 2257/80: Water
- C01B 2203/0244: the reforming step being an autothermal reforming step, e.g. secondary reforming processes
- C01B 2203/0283: containing a CO-shift step, i.e. a water gas shift step
- C01B 2203/0294: containing three or more CO-shift steps
- C01B 2203/0415: Purification by absorption in liquids
- C01B 2203/0475: the impurity being carbon dioxide
- C01B 2203/0495: the impurity being water
- C01B 2203/0811: by combustion of fuel
- C01B 2203/0883: by indirect heat exchange
- C01B 2203/143: Three or more reforming, decomposition or partial oxidation steps in series
- C01B 2210/0021: Temperature swing adsorption
- C01B 2210/0062: Water
- Y02C 20/20: of methane
- Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2
- Y02P 30/00: Technologies relating to oil refining and petrochemical industry
- 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)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A process and plant for producing a high purity CO2 product, comprising: providing a CO2-rich stream containing hydrocarbons, hydrogen and/or CO, combining it with a stream rich in methane (CH4), and mixing it with oxygen, thereby forming a CO2/O2- mixture; subjecting the CO2/O2- mixture to a catalytic oxidation step, thereby producing a purified stream having a higher CO2 and/or H2O concentration; removing H2O from said purified stream, for producing said high purity CO2 product stream. The CO2-rich stream is for instance derived from the CO2-removal section of a plant for producing hydrogen.

## Claims

### Claim 1

A process for producing a high purity CO2 product, comprising the steps of:
i) providing a CO2-rich stream containing hydrocarbons, hydrogen and/or CO; combining it with a stream rich in methane (CH4); and mixing it with oxygen, thereby forming a CO2/O2- mixture;
ii) subjecting the CO2/O2- mixture to a catalytic oxidation step, thereby producing a purified stream having a higher CO2 and/or H2O concentration;
iii) removing H2O from said purified stream, for producing said high purity CO2 product.

### Claim 2 (depends on 1)

The process of claim 1, wherein the catalytic oxidation step is conducted in two or more steps with intermediate addition of oxygen.

### Claim 3 (depends on 1)

The process of claim 1, wherein in step iii) the removing of H2O comprises passing the purified stream to a cooling train including one or more cooling units for thereby producing a cooled purified stream, and subsequently passing the cooled purified stream to a condensing step.

### Claim 4 (depends on 3)

The process of claim 3, wherein the cooling train includes a cooling unit using N2 from an air separation unit (ASU).

### Claim 5 (depends on 1)

The process of claim 1, wherein the oxygen is generated from an air separation unit (ASU) and/or a water/steam electrolysis unit.

### Claim 6 (depends on 1)

The process of claim 1, wherein step iii) further comprises a drying step, preferably after conducting said condensing step.

### Claim 7 (depends on 6)

The process of claim 6, wherein said drying step is conducted in a temperature swing adsorption unit.

### Claim 8 (depends on 1)

The process of claim 1, wherein the CO2-rich stream of step i) is derived from a CO2-removal section, said CO2-removal section being arranged to receive a shifted synthesis gas stream, in which the CO2-removal section is an amine wash unit and comprises a CO2-absorber, a CO2-stripper and a low-pressure flash drum, from which said CO2-rich stream is separated.

### Claim 9 (depends on 8)

The process of claim 8, wherein the CO2-removal section comprises a highpressure flash drum and the process further comprises adding hydrogen to said CO2-rich stream.

### Claim 10 (depends on 1)

The process of claim 1, wherein step i) comprises:
supplying a hydrocarbon feed to a reforming section, and converting it to a stream of synthesis gas;
withdrawing a stream of synthesis gas from the reforming section and supplying it to a shift section, shifting the synthesis gas in a high temperature shift (HTS)-step, and optionally also in a medium temperature shift (MTS) and/or low temperature shift (LTS)-shit step, thereby providing a shifted synthesis gas stream;
supplying the shifted synthesis gas stream from the shift section to a CO2 removal section, suitably said amine wash unit, and separating said CO2-rich stream from said shifted synthesis gas stream, thereby providing a H2-rich stream.

### Claim 11 (depends on 10)

The process of claim 10, wherein the reforming section comprises autothermal reforming (ATR), and optionally also pre-reforming said hydrocarbon feed in one or more prereformer units prior to it being fed to the ATR.

### Claim 12 (depends on 10)

The process of claim 10, further comprising preheating said hydrocarbon feed in one or more fired heaters and feeding at least a part of said H2-rich stream as hydrocarbon fuel to the at least one or more fired heaters.

### Claim 13 (depends on 1)

The process of claim 1, wherein the process is absent of a hydrogen purification step.

### Claim 14

A plant for producing a high purity CO2 product, said plant comprising:
a conduit for mixing an oxygen stream, preferably oxygen generated from an air separation unit (ASU) and/or a water/steam electrolysis unit, with a CO2-rich stream containing hydrocarbons, hydrogen and/or CO; and a conduit for combining a stream rich in methane (CH4), with said CO2-rich stream; thereby forming an inlet gas comprising a mixture of carbon dioxide and oxygen;
a catalytic oxidation (CATOX) unit arranged to receive said inlet gas comprising a mixture of carbon dioxide and oxygen, said CATOX unit comprising an outlet for withdrawing an outlet gas as a purified stream having a higher CO2 and/or H2O concentration;
a cooling train arranged to receive said outlet gas from the CATOX unit, said cooling train comprising one or more cooling units for cooling the outlet gas;
a condensate separator arranged to receive the thus cooled outlet gas and for removing H2O, thereby forming an outlet product comprising said high purity CO2 product.

### Claim 15

Use of a CATOX unit for purifying a CO2-rich stream containing hydrocarbons, hydrogen and/or CO, which is derived from a process or plant for producing hydrogen, in particular from a CO2-removal section thereof, while not increasing the carbon emission of the plant.