# US 10,246,330 B2 · Systems and processes for removing hydrogen sulfide from gas streams

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- Number: US 10,246,330 B2
- Document ID: US10246330B2
- Status: Granted
- Kind: B2
- Application number: 15/486,553
- Filed: 2017-04-13
- Published: 2018-10-18
- Granted: 2019-04-02
- Earliest claimed: 2017-04-13
- Assignees: Marsulex Environmental Technologies Corporation
- Applicants: Marsulex Environmental Technologies Corporation
- Inventors: Michael Lyn Mengel; Amy Patrice Evans; Eli Gal; Paul Murray Leicht
- Web page: https://patentgrep.com/patent/US10246330B2

## CPC

- C01B 17/64: Thiosulfates; Dithionites; Polythionates
- B01D 53/1468: {Removing hydrogen sulfide}
- B01D 53/1493: {Selection of liquid materials for use as absorbents}
- B01D 53/96: Regeneration, reactivation or recycling of reactants
- C05C 3/00: Fertilisers containing other salts of ammonia or ammonia itself, e.g. gas liquor
- C05G 5/23: Solutions
- B01D 2252/102: Ammonia
- B01D 2257/304: Hydrogen sulfide
- B01D 2257/504: Carbon dioxide
- Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- 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)
- C05C: NITROGENOUS FERTILISERS
- C05G: MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS (organic fertilisers containing added bacterial cultures, mycelia, or the like C05F11/08; organic fertilisers containing plant vitamins or hormones C05F11/10); FERTILISERS CHARACTERISED BY THEIR FORM
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A process and system for hydrogen sulfide capture from gas streams employing an absorber vessel in which the gas stream containing hydrogen sulfide is contacted with an absorbent solution to remove the hydrogen sulfide from the gas stream. The process and system may further employ an oxidation vessel in which sulfides and/or bisulfides in the absorbent solution are oxidized to produce a thiosulfate and/or sulfate, yielding a solution that can be used as fertilizer or other applications.

## Claims

### Claim 1

A process of capturing hydrogen sulfide from a gas stream and oxidizing captured hydrogen sulfide to form a thiosulfate, a sulfate, or a combination thereof, the process comprising:
obtaining a gas stream containing hydrogen sulfide, the gas stream being natural gas, refinery process gas, or syngas from gasification;
contacting the gas stream with a first absorbent solution to form sulfides in the first absorbent solution, wherein the first absorbent solution is an ammoniated aqueous absorbent solution containing ammonia and ammonium thiosulfate and/or ammonium sulfate and the ammonia reacts with the hydrogen sulfide to form the sulfides;
controlling pH of the first absorbent solution during the contacting step;
oxidizing the first absorbent solution to convert at least some of the sulfides thereof to form an additional amount of ammonium thiosulfate and/or ammonium sulfate, thereby producing a second absorbent solution that contains the additional amount of ammonium thiosulfate and/or ammonium sulfate and has a lower sulfide content than the first absorbent solution; and
delivering a first portion of the second absorbent solution for use in the contacting step to capture residual hydrogen sulfide in the gas stream and capture ammonia emitted from the first absorbent solution; and
discharging a second portion of the second absorbent solution from the system.

### Claim 2 (depends on 1)

The process of claim 1, wherein the first absorbent solution consists essentially of the ammonia, the sulfides, the ammonium thiosulfate and/or ammonium sulfate, and water.

### Claim 3 (depends on 2)

The process of claim 2, wherein the sulfides comprise ammonium bisulfide and ammonium sulfide.

### Claim 4 (depends on 1)

The process of claim 1, wherein the first absorbent solution consists of the ammonia, the sulfides, the ammonium thiosulfate and/or ammonium sulfate, and water.

### Claim 5 (depends on 4)

The process of claim 4, wherein the sulfides comprise ammonium bisulfide and ammonium sulfide.

### Claim 6 (depends on 1)

The process of claim 1, wherein the ammoniated aqueous absorbent solution contains ammonium thiosulfate and the oxidizing of the ammoniated aqueous absorbent solution converts at least some of the sulfides thereof to additional ammonium thiosulfate.

### Claim 7 (depends on 1)

The process of claim 1, wherein the pH of the ammoniated aqueous absorbent solution is controlled during the contacting step by adding ammonia to the ammoniated aqueous absorbent solution.

### Claim 8 (depends on 1)

The process of claim 1, wherein the contacting step is performed at an elevated pressure.

### Claim 9 (depends on 8)

The process of claim 8, wherein the oxidizing step is performed at a second elevated pressure that is less than the elevated pressure of the contacting step.

### Claim 10

A process of capturing hydrogen sulfide from a gas stream and oxidizing captured hydrogen sulfide to form a thiosulfate, a sulfate, or a combination thereof, the process comprising:
obtaining a gas stream containing hydrogen sulfide, the gas stream being natural gas, refinery process gas, or syngas from gasification;
contacting the gas stream with an ammoniated aqueous absorbent solution containing ammonia and ammonium thiosulfate and/or ammonium sulfate, the ammonia reacting with the hydrogen sulfide to form sulfides in the ammoniated aqueous absorbent solution;
controlling pH of the ammoniated aqueous absorbent solution during the contacting step by adding ammonia to the ammoniated aqueous absorbent solution;
oxidizing the ammoniated aqueous absorbent solution to convert at least some of the sulfides thereof to form an additional amount of ammonium thiosulfate and/or ammonium sulfate, thereby producing a second absorbent solution that contains the additional amount of ammonium thiosulfate and/or ammonium sulfate and has a lower sulfide content than the ammoniated aqueous absorbent solution; and
delivering a first portion of the second absorbent solution for use in the contacting step to capture residual hydrogen sulfide in the gas stream and capture ammonia emitted from the first absorbent solution; and
discharging a second portion of the second absorbent solution from the system.

### Claim 11 (depends on 10)

The process of claim 10, wherein the ammoniated aqueous absorbent solution contains ammonium thiosulfate and the oxidizing of the ammoniated aqueous absorbent solution converts at least some of the sulfides thereof to additional ammonium thiosulfate.

### Claim 12 (depends on 10)

The process of claim 10, wherein the pH of the ammoniated aqueous absorbent solution is about 5 to about 10.

### Claim 13 (depends on 10)

The process of claim 10, further comprising using water to wash the gas stream following the contacting step to reduce ammonia concentration therein.

### Claim 14 (depends on 10)

The process of claim 10, wherein the sulfides in the ammoniated aqueous absorbent solution are maintained at a concentration of about 100 to about 50,000 mg/liter by adjusting the concentration of the ammonium sulfate solution used in the contacting step.

### Claim 15 (depends on 10)

The process of claim 10, wherein the contacting step is performed at a pressure of about 1 to about 100 bar.

### Claim 16 (depends on 10)

The process of claim 10, further comprising using a catalyst to enhance the oxidation of the sulfides to the ammonium thiosulfate and/or the ammonium sulfate during the oxidation step.

### Claim 17 (depends on 16)

The process of claim 16, wherein the catalyst is iron in ferric or ferrous state.

### Claim 18 (depends on 10)

The process of claim 10, wherein the oxidizing step is performed with an oxygen-containing gas chosen from the group consisting of air, oxygen, oxygen-enriched air, hydrogen peroxide, or combinations thereof.

### Claim 19 (depends on 18)

The process of claim 18, further comprising using water to wash the oxygen-containing gas following the oxidation step to reduce ammonia concentration therein.