The Need

Hydrogen sulfide (H₂S) is a highly toxic and corrosive impurity in syngas, natural gas, biogas, and sulfur plant tail gas. Its removal is essential for safety, regulatory compliance, and downstream processing such as carbon capture and sulfur recovery. However, H₂S is typically present with large amounts of CO₂, making selective separation challenging. Existing technologies are energy-intensive, complex, and costly, creating a strong need for simpler, more selective alternatives.

The Technology

OSU engineers have developed a membrane-based gas separation platform that selectively removes H₂S from H₂S/CO₂ mixtures at elevated temperatures. The membranes employ a facilitated transport mechanism using sterically hindered amine carriers embedded in a polymer matrix. By exploiting fundamental differences in how H₂S and CO₂ interact with amines, the membrane preferentially transports H₂S while suppressing CO₂ transport. The result is high H₂S/CO₂ selectivity combined with industrially relevant flux, enabling compact, continuous separation without solvent regeneration.

Commercial Applications

• Syngas desulfurization in IGCC and hydrogen production plants
• CO₂ purification prior to sequestration or enhanced oil recovery
• H₂S removal from natural gas and biogas streams
• Tail gas treatment upstream of Claus sulfur recovery units

Benefits/Advantages

• High selectivity at high temperature: Enables H₂S/CO₂ separation where conventional membranes and solvents struggle.
• Lower energy and process complexity: Eliminates solvent regeneration and reduces parasitic energy demand.
• Compact and modular: Suitable for retrofit or integration into existing gas processing flowsheets.
• Improved economics: Potential to reduce overall cost of electricity or gas treatment compared to absorption-based systems.