# US 2017/0282115 A1 · Removal of hydrogen sulphide and carbon dioxide from a stream of fluid

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- Number: US 2017/0282115 A1
- Document ID: US20170282115A1
- Status: Published application
- Kind: A1
- Application number: 15/506,635
- Filed: 2015-08-20
- Published: 2017-10-05
- Earliest claimed: 2014-08-25
- Assignees: BASF SE
- Applicants: BASF SE
- Inventors: Thomas INGRAM; Ralf NOTZ; Gerald VORBERG; Georg SIEDER
- Web page: https://patentgrep.com/patent/US20170282115A1

## CPC

- B01D 53/1462: {Removing mixtures of hydrogen sulfide and carbon dioxide}
- B01D 53/1493: {Selection of liquid materials for use as absorbents}
- C07C 217/08: the oxygen atom of the etherified hydroxy group being further bound to an acyclic carbon atom
- B01D 2252/2026: Polyethylene glycol, ethers or esters thereof, e.g. Selexol
- B01D 2252/20405: Monoamines
- B01D 2252/2041: Diamines
- B01D 2252/20426: Secondary amines
- B01D 2252/20431: Tertiary amines
- B01D 2252/20484: with one hydroxyl group
- B01D 2252/502: having two or more functionalities in the same molecule other than alkanolamine
- B01D 2252/504: Mixtures of two or more absorbents
- Y02C 20/40: of CO2
- 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)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

A process for removing hydrogen sulfide and carbon dioxide from a fluid stream comprises a) an absorption step in which the fluid stream is contacted with an absorbent comprising an aqueous solution (i) of an amine of the general formula (I) in which R1, R2 and R3 are each independently selected from C1-4-alkyl and C1-4-hydroxyalkyl; each R4 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; each R5 is independently selected from hydrogen, C1-4-alkyl and C1-4-hydroxyalkyl; X is OH or NH(CR1R2R3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1; and optionally (ii) at least one tertiary amine, where the molar ratio of (i) to (ii) is greater than 0.05; wherein at least 90% of the hydrogen sulfide is removed from the fluid stream and selectivity for hydrogen sulfide over carbon dioxide is not greater than 8, wherein a CO2- and H2S-laden absorbent is obtained; b) a regeneration step in which at least a substream of the CO2- and H2S-laden absorbent is regenerated and a regenerated absorbent is obtained; and c) a recycling step in which at least a substream of the regenerated absorbent is recycled into the absorption step a). The process allows a high level of hydrogen sulfide removal with a simultaneously high coabsorption of carbon dioxide.

## Claims

### Claim 1

A process for removing hydrogen sulfide and carbon dioxide from a fluid stream, the process comprising
a) contacting the fluid stream with an absorbent comprising an aqueous solution of
(i) an amine of formula (I)
in which R1, R2 and R3 are each independently C1-4-alkyl or C1-4-hydroxyalkyl; each R4 is independently hydrogen, C1-4-alkyl or C1-4-hydroxyalkyl; each R5 is independently hydrogen, C1-4-alkyl or C1-4-hydroxyalkyl, X is OH or NH(CR1R2R3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1;
and optionally (ii) at least one tertiary amine, where a molar ratio of (i) to (ii) is greater than 0.05;
wherein there is a partial hydrogen sulfide pressure of at least 0.1 bar and a partial carbon dioxide pressure of at least 1 bar in the fluid stream;
wherein the fluid stream has a total pressure of at least 20 bar,
wherein at least 90% of the hydrogen sulfide is removed from the fluid stream;
wherein a CO2- and H2S-laden absorbent and a treated fluid stream are obtained; and
wherein a selectivity S for hydrogen sulfide over carbon dioxide calculated as follows is not greater than 8;
S
=
y

(
H
2

S
)
feed
-
y

(
H
2

S
)
treat
y

(
H
2

S
)
feed
y

(
CO
2
)
feed
-
y

(
CO
2
)
treat
y

(
CO
2
)
feed
,
in which y(H2S)feed is a molar proportion of H2S in the fluid stream, y(H2S)treat is a molar proportion in the treated fluid stream, y(CO2)feed is a molar proportion of CO2 in the fluid stream and y(CO2)treat is a molar proportion of CO2 in the treated fluid stream;
b) regenerating at least a substream of the CO2- and H2S-laden absorbent to obtain a regenerated absorbent; and
c) recycling at least a substream of the regenerated absorbent into a).

### Claim 2 (depends on 1)

The process according to claim 1, wherein a total concentration of (i) and (ii) in the aqueous solution is 10% to 60% by weight.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the amine (i) is 2-(2-tert-butylaminoethoxy)ethanol.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the aqueous solution comprises the at least one tertiary amine (ii), which is methyldiethanolamine.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the absorbent does not comprise any sterically unhindered primary or secondary amines.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the absorbent comprises at least one organic solvent.

### Claim 7 (depends on 1)

The process according to claim 1, wherein the fluid stream comprises at least one hydrocarbon.

### Claim at position 8

8-9. (canceled)

### Claim 10 (depends on 1)

The process according to claim 1, wherein the CO2- and H2S-laden absorbent is regenerated b) to an H2S loading corresponding to an equilibrium loading for an H2S content of less than 90% of a H2S content of the treated fluid stream.

### Claim 11 (depends on 1)

The process according to claim 1, wherein a cumulated CO2 and H2S loading of the CO2- and H2S-laden absorbent is at least 0.25 mol/mol and a cumulated CO2 and H2S loading of the regenerated absorbent is less than 0.20 mol/mol.

### Claim 12 (depends on 1)

The process according to claim 1, wherein the regenerating b) comprises at least one measure of heating, decompressing and stripping with an inert fluid.

### Claim 13 (depends on 1)

The process according to claim 1, further comprising:
d) passing at least a substream of the CO2- and H2S-containing gas stream released in b) into a Claus plant to obtain a Claus tail gas, which is hydrogenated to obtain a hydrogenated Claus tail gas;
e) treating the hydrogenated Claus tail gas with the regenerated absorbent to obtain a first H2S-laden absorbent; and
f) passing the first H2S-laden absorbent into b) and/or into a).

### Claim 14 (depends on 13)

The process according to claim 13, wherein the treating e) is effected at a lower pressure than a pressure in a).

### Claim 15 (depends on 1)

The process according to claim 1, further comprising:
d′) treating a sub stream of a CO2- and H2S-containing gas stream released in b) with the regenerated absorbent to obtain a second H2S-laden absorbent; and
e′) passing the second H2S-laden absorbent into b).

### Claim 16 (depends on 15)

The process according to claim 15, wherein the substream of the CO2- and H2S-laden absorbent is passed into d′).

### Claim 17 (depends on 15)

The process according to claim 15, further comprising:
f′) passing the substream of the CO2- and H2S-containing gas stream released in b) into a Claus plant to obtain a Claus tail gas, which is hydrogenated to obtain a hydrogenated Claus tail gas;
g′) treating the hydrogenated Claus tail gas with the regenerated absorbent to obtain a first H2S-laden absorbent; and
h′) passing the first H2S-laden absorbent into b) and/or into a).

### Claim 18 (depends on 1)

The process according to claim 1, further comprising
i″) recycling and passing into a) a substream of the CO2- and H2S-containing gas stream released in b).

### Claim 19 (depends on 1)

The process according to claim 1, wherein b) comprises:
b1) decompressing the CO2- and H2S-laden absorbent is to obtain a CO2-containing gas stream and a partly regenerated absorbent; and
b2) heating and/or stripping the partly regenerated absorbent to obtain the regenerated absorbent;
and wherein the process further comprises:
d″) treating the CO2-containing gas stream with the regenerated absorbent to obtain a third H2S-laden absorbent; and
e″) passing the third H2S-laden absorbent into b).

### Claim 20 (depends on 19)

The process according to claim 19, further comprising:
f″) decompressing the CO2- and H2S-laden absorbent to a pressure between a pressure in a) and a pressure in b1), in order to release essentially dissolved gas constituents other than carbon dioxide and hydrogen sulfide from the CO2- and H2S-laden absorbent.