Membrane Separation Technologies
As part of a clean energy research focus, RTI International is developing advanced gas
separation membranes and membrane-based processes for removing contaminants
from industrial process gas streams, including gasification synthesis gas and postcombustion flue gas. RTI has a dedicated team of researchers and state-of-the-art
laboratory facilities to carry out the synthesis, characterization, and evaluation of
membrane materials and processes. RTI has also developed membrane process
simulation software for modeling multicomponent gas separation processes.
Membrane Separation Technologies
Polymer Membranes
For many industrially important applications, membranebased gas separation is a viable, cost-effective, alternative
(or complement) to traditional unit operations such
as distillation, absorption, pressure swing adsorption,
compression-condensation, and cryogenics. Membrane
processes have inherent advantages over conventional
separation operations, including:
RTI membrane research activities are focused in two
areas: development of size-selective and “reverse-selective”
polymeric membrane materials. Unlike size-selective
membranes, reverse-selective polymer membranes are
more permeable to larger, more condensable or more polar
gases (e.g., carbon dioxide, hydrogen sulfide, condensable
hydrocarbons, etc.) than to smaller, less condensable gases
(e.g., hydrogen).
• Separation and concentration of contaminants into a
single process stream
• Continuous processing—does not require thermal or
pressure cycling
• Modular design suitable for scale-up
• Compact design for easy retrofit and integration into
existing and new processes
• Minimal maintenance and operator attention.
RTI, in collaboration with industrial, academic, and
government partners, develops cost-effective membranes
and membrane processes for industrial gas separation
applications, particularly for syngas cleaning and
conditioning and carbon dioxide capture from postcombustion flue gas.
RTI has developed novel reverse-selective polymeric
membranes for cleaning and conditioning syngas streams
to meet contaminant control targets for power generation
and chemical processes. In these applications, the reverseselective membranes selectively separate carbon dioxide,
hydrogen sulfide, and carbonyl sulfide as a low-pressure
waste stream, leaving the hydrogen- and carbon monoxideenriched product stream at high pressure. The chemistry of
these membranes is tailored to give them high permeability
and selectivity for polar and acidic gas species. Process
modeling has shown that reverse-selective membrane
processes can provide significant cost advantages over
industry-standard amine-based acid gas removal systems.
www.rti.org
Membrane Separation Technologies (continued)
RTI and collaborators have developed unique reverse-selective
membranes that achieve step-out separation performance
through targeted harnessing of plasticization by acidic or
polar species.
(Science, Vol. 311, pp. 639-642, February 2006)
RTI has also developed hydrogen-selective polymer
membranes with high thermal stability (decomposition
temperature >500 °C ). These membranes produce purified
hydrogen from syngas and reformate gas and are useful for
direct application to high-temperature gasifier or water-gasshift reactor process streams. They also produce a highpressure, concentrated carbon dioxide stream that is suitable
for sequestration or reuse.
In another U.S. Department of Energy-funded project,
RTI and a team of industrial partners have developed and
integrated a polymer membrane-based process for capturing
carbon dioxide from post-combustion flue gas. This project
is focused on three areas: new high-performance membrane
materials, improved hollow-fiber membrane module design,
and cost- and energy-efficient integration into existing coalfired power plants.
RTI has explored a carbon dioxide capture concept that
combines a gas-selective membrane with a reactive solvent
technology. This hybrid process exploits the advantages of the
individual technologies while mitigating their drawbacks.
Membrane Preparation, Development, and
Characterization
RTI has in-house expertise and fully equipped facilities for
membrane synthesis, characterization, and testing. Membrane
permeation testing facilities at RTI are well-equipped for
determining gas permeances and selectivities of planar
and tubular, polymeric and inorganic membrane materials
and membrane modules over a wide range of pressure and
temperature operating conditions and gas environments
in bench- and pilot-scale systems. RTI’s membrane testing
facilities also allow the determination of the long-term effect
of realistic gas environments on membrane performance. The
range of test conditions include
• Multicomponent gas mixtures at high pressures (up to 1,500
psia) and high temperatures (up to 350 °C)
• Toxic and corrosive gases (CO, H2S, CO2, SO2, etc.)
• Humidified gas mixtures.
Pilot-Plant Operation
RTI has experience with the design and operation of pilotscale membrane process units. RTI’s membrane pilot skids can
be integrated into existing operations to demonstrate longterm performance with actual process gases.
Doing Business with RTI
We work closely with commercial, government, and
academic partners to maintain a portfolio of innovative
energy technologies with a high potential for commercial
success. Strategic alliances with industry partners ensure that
economic and technical feasibility are part of our thinking
from initial concept through to the development stages.
Our focus is on joint development activities, but we also
provide commercial clients with specialized research and
development, testing, and analytical services.
More Information
Markus Lesemann
Energy Technology Division
919.541.6246
mlesemann@rti.org
RTI International
3040 E. Cornwallis Road, PO Box 12194
Research Triangle Park, NC 27709-2194 USA
www.rti.org/energy
RTI 6486 R4 0214
RTI International is one of the world’s leading research institutes, dedicated to improving the human condition by
turning knowledge into practice. Our staff of more than 3,700 provides research and technical services to governments
and businesses in more than 75 countries in the areas of health and pharmaceuticals, education and training,
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environment, and laboratory testing and chemical analysis. For more information, visit www.rti.org.
RTI International is a trade name of Research Triangle Institute.