Separation of hydrogen sulfide from natural gas
AssigneeExxonMobil Research and Engineering Company
InventorsPavel Kortunov, Michael Siskin, Robert B. Fedich
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Abstract
A process for increasing the selectivity of an alkanolamine absorption process for selectively removing hydrogen sulfide (H2S) from a gas mixture which also contains carbon dioxide (CO2) and possibly other acidic gases such as COS, HCN, CS2 and sulfur derivatives of C1 to C4 hydrocarbons, comprises contacting the gas mixture with a liquid absorbent which is a severely sterically hindered capped alkanolamine or more basic sterically hindered secondary and tertiary amine. The improvement in selectivity is achieved at the high(er) pressures, typically least about 10 bara at conditions nearing the H2S/CO2 equilibrium at which CO2 begins to displace absorbed hydrosulfide species from the absorbent solution.
Claims35
A cyclic separation process for selectively separating hydrogen sulfide (H2S) from a gas mixture which also comprises carbon dioxide (CO2), which process comprises:
- contacting a stream of the gas mixture with a solution of a capped alkanolamine H2S absorbent at a pressure of at least 1 bara.
A method of increasing the selectivity of an alkanolamine absorption process for H2S absorption from a gas mixture which also comprises carbon dioxide (CO2), which comprises contacting a stream of the gas mixture with a solution of a capped alkanolamine H2S absorbent having at least one capped hydroxyl group at a pressure of at least 1 bara.
An alkanolamine separation process for a natural gas stream containing H2S and CO2 with improved selectivity for H2S separation relative to CO2 separation at high pressures under conditions approaching absorbed H2S/CO2 equilibrium, which comprises:
- (i) contacting a natural gas stream containing H2S and CO2 in an absorption zone with a liquid solution of a sterically hindered capped alkanolamine to absorb H2S preferentially over CO2 and form a rich stream of the absorbed H2S in the alkanolamine solution;
- (ii) passing the rich stream from the absorption zone to at least one regeneration zone and desorbing the absorbed H2S as gas from the alkanolamine solution to form a lean solution containing a reduced concentration of absorbed H2S relative to the rich stream and
- (iii) returning the lean stream to the absorption zone.
A cyclic separation process for selectively separating hydrogen sulfide (H2S) from a gas mixture which also comprises carbon dioxide (CO2), which process comprises:
- contacting a stream of the gas mixture with a solution of a sterically hindered secondary or tertiary amine H2S absorbent at a pressure of at least 1 bara.
A cyclic separation process for a natural gas stream containing H2S and CO2 with improved selectivity for H2S separation relative to CO2 separation at high pressures under conditions approaching absorbed H2S/CO2 equilibrium, which comprises:
- (i) contacting a natural gas stream containing H2S and CO2 in an absorption zone with a non-aqueous liquid solution of a sterically hindered secondary or tertiary amine to absorb H2S preferentially over CO2 and form a rich stream of the absorbed H2S in the alkanolamine solution;
- (ii) passing the rich stream from the absorption zone to at least one regeneration zone and desorbing the absorbed H2S as gas from the amine solution to form a lean solution containing a reduced concentration of absorbed H2S relative to the rich stream and
- (iii) returning the lean stream to the absorption zone.
Dependencies are inferred from the claim text.