Gas treating (FLEXSORB™)

Selective H₂S removal (FLEXSORB™)  

ExxonMobil’s FLEXSORB technology enables customers to process increasingly sour gas streams while helping to meet stringent emission regulations and sulfur recovery objectives. The highly selective H2S removal process has been used in tail gas treating (TGT), acid gas enrichment (AGE) and high-pressure acid gas removal (AGR) units. The technology provides a cost-effective way to meet low H2S specifications while minimizing CO2 co-absorption.

The FLEXSORB SE technology is designed for the selective removal of H2S in the presence of CO2 and utilizes proprietary severely sterically hindered amines. The unique characteristics of the amine allow it to achieve high H2S cleanup selectively at low solvent circulation rates. This gas treating technology has been proven in over 100 commercial units worldwide and is considered the best available technology in many regions, enabling facilities to meet stringent emissions standards. FLEXSORB SE Plus can help to meet or exceed the World Bank Standard (WBS) SO2 emission limit of 150 mg/Nm3, equivalent to approximately 99.98% sulfur recovery efficiency (SRE).

Two variations:  

  • FLEXSORB SE is used for selective removal of H2S
  • FLEXSORB SE Plus is used to meet ultra low H2S specifications (< 10 vppm) even at the low pressures.

Key benefits

  • gas treating low operating costs

    • Low circulation rate
    • Low energy consumption
    • Long solvent life and resistant to performance deterioration overtime
    • Simple to operate

  • gas treating low capital costs

    • Smaller pumps and heat exchangers
    • Smaller columns
    • Uses standard gas treating equipment

  • gas treating environmental benefits

    • Meets stringent H2S emissions targets to improve environmental performance
    • Meets H2S standards even at low pressure or higher lean temperature

Tail Gas Treating Unit (TGTU)  

In sulfur plant TGTU applications, FLEXSORB™ SE and SE Plus solvents require about half of the circulation rate and regeneration energy of other solvents based on methyldiethanolamine (MDEA). CO2 rejection is very high, typically above 90%. Lower circulation rate translates into smaller heat exchangers and a smaller regenerator tower, thereby reducing investments for grassroots projects. For existing units, FLEXSORB SE and SE Plus solvents allow the unit to be debottlenecked with few or no equipment modifications.

gas treating tail gas treating unit process

High Pressure natural gas treating  

In natural gas treating, selective H2S removal from natural gas can be advantageous whenever a portion of the CO2 can remain in the treated gas. In one natural gas treating facility, conversion to FLEXSORB SE solvent allowed the unit to increase gas production by 27% without modification of the existing hardware. At the same time, the circulation rate and reboiler duty was lowered to 65% and 78% of the design, respectively. FLEXSORB SE also improved the CO2 slip and the operability of the unit by reducing the co-absorption of heavy hydrocarbons.

Onshore treating facility  

gas treating onshore treating facility table

Acid gas enrichment  

ExxonMobil’s FLEXSORB SE or SE Plus solvents are in use in a wide variety of Acid Gas Enrichment (AGE) designs around the world, enabling reserves that contain more CO2 than H2S to be economically developed. As the name implies, an AGE unit enriches the H2S content of the acid gas stream, making it practical to recover sulfur in a conventional Claus unit. In applications where acid gas injection instead of Claus is used, FLEXSORB technology can be used to minimize the volume of acid gas for re-injection.

Featured resources

View highlighted news, events, technical papers and case studies below. To see our full collection of resources, browse our Library.
  • ExxonMobil Chemical Library icon

    Comparison of Amine-based TGTU Technologies Article from Hydrocarbon Engineering with Flexsorb reference

    Article: Comparison of Amine-based TGTU Technologies

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  • ExxonMobil Chemical Library icon

    ExxonMobil Catalysts and Licensing LLC and BASF Corporation to demonstrate the next generation of high performance selective solvent to decrease sulfur emissions

    Innovative technology improves selective removal of H₂S and minimizes absorption of CO₂ from gas streams.

    Read more
  • ExxonMobil Chemical Library icon

    ExxonMobil Catalysts and Licensing LLC, BASF Corporation form gas treating alliance for natural gas processing and petroleum refining

    The alliance leverages ExxonMobil and BASF’s collective expertise to meet customer needs.

    Learn more
  • ExxonMobil Chemical play button icon

    A Particle of Difference

    How ExxonMobil Catalysts and Technology Licensing solves shared challenges through expertise, specialty catalysts, technology licensing and collaboration.

    Watch the video
  • ExxonMobil Chemical Library icon

    ExxonMobil Catalysts and Technology Licensing – summary of technologies offered

    Learn about the cutting-edge, proprietary catalysts and advantaged process technologies that ExxonMobil provides for refining, gas and chemical needs.

    Read more
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