DESCRIPTION
Polymeric membranes are synthetic materials widely used for gas separation, particularly in CO2 capture applications. They consist of polymer chains with specialized structures that enable the selective permeation of specific gases, such as CO2, over others like N2 or O2. The separation process is pressure-driven and relies on the solution-diffusion mechanism, where CO2 molecules dissolve into the polymer matrix and diffuse through it more readily than other gases. This selectivity depends on the membrane material's chemical and physical properties.
Gas separation using membranes can be done in single or multi-stage processes. Single-stage processes need high selectivity for high CO2 purities and recoveries, but this is challenging due to low CO2 content and the recovery-purity trade-off. Multi-stage processes, as shown in the figure, with gas recycling, achieve higher purity and recovery but require more power and membrane area. The main goal is to minimize energy consumption and membrane area.1
TECHNICAL ASPECTS (all % are volume-based)
Point sources: Natural gas plants, power plants, cement, steel, waste-to-energy, paper & pulp hydrogen production, biogas upgrading, and ammonia production facilities.2
CO2 concentration range: 10-70%2
CO2 capture efficiency: >90%2
CO2 purity: >95% (3-stage)3
Min. feed gas pressure: 13,4 – 65 bar
Max. feed gas temperature: 30-60 °C (post-combustion) and 150-200 °C (pre-combustion)6
Typical scale: Small to Large (modular)
Primary energy source: Electricity
Impurity tolerance: No tolerance.7
FUNCTION IN CCU VALUE CHAIN
- Capture CO2 from flue gases.
- Increase CO2 concentration for a hybrid system.
- Purify CO2 streams.
LIMITATIONS
- Polymeric membranes are susceptible to degradation or fouling when exposed to impurities such as SOx, H2S, or particulates (PM), requiring pretreatment steps.7,8
- Achieving high CO2 purity in the permeate stream typically necessitates multi-stage membrane systems or hybrid approaches.3
- Polymeric membranes generally operate best within a moderate range of temperatures and pressures.7
- Certain polymeric membranes are sensitive to moisture, which can impact their selectivity and permeability over time.7
ENERGY
- Electricity is primarily used by the compressor or blower to pressurize the feed gas and by a vacuum pump, if used on the permeate side.
CONSUMABLES
- Membranes themselves need to be replaced periodically.
- Cooling water is required to cool the feed gas and intermediate streams after compression.
| Parameter | Value |
|---|---|
| Electricity (kWh/tCO2) * | 2075 - 5009 |
|
* Variable depending on number of stages, membrane flux, feed gas, and vacuum pressures. 5 Two-stage polyactive™ membrane system; feed gas: 13.5% CO2; purity 96%; feed pressure – 6 bar; vacuum pressure – 0.2 bar; excluding compression. 9 Three-stage; CO2 conc. – 12% dry; flue gas stream – 5000 t/d; capture efficiency – 90%; CO2 purity – 96%; inlet pressure – 1.6-2.3 bar; includes CO2 compression to 110 bar. |
|
COSTS
CAPEX: 35 – 40 €/tCO2 9
Main CAPEX: compressors, vacuum pumps, and membranes.
(lower range – high flux and upper range – low flux)
OPEX: 35 – 75 €/tCO2 9
Main OPEX: electricity for compressors and vacuum pumps.
(lower range – low flux and upper range – high flux)
CO2 capture cost: 75 - 110 €/tCO2 9
(lower range – low flux and upper range – high flux)
9 Three-stage; CO2 conc. – 12% dry; flue gas stream – 5000 t/d; capture efficiency – 90%; CO2 purity – 96%; inlet pressure – 1.6-2.3 bar; includes CO2 compression to 110 bar; CRF – 0.154; 2019 euros; 8000 hr/yr; membrane price – 45 €/m2; electricity price – 62.5 €/MWh.
CO2 avoidance cost: 84 €/tCO2 avoided 10
10 2-stage membrane system; IGCC plant; CO2 conc. – 38.6%; lifetime – 25 yrs; discount rate – 8%; 2015 euros; includes CO2 compression to 110 bar.
ENVIRONMENTAL
CO2 footprint: 287 kgCO2e/tCO2 5
5 Two-stage polyactive™ membrane system; feed gas: 13.5% CO2; purity 96%; feed pressure – 6 bar; vacuum pressure – 0.2 bar; including compression; cradle-to-grave.
Spatial footprint: 3900 m2 for 0.2 MtCO2/yr 11
11 Land cost – 25.6 €/m2; estimation includes flue gas cooling, CO2 capture, compression and liquefaction.
418 m2 for 13750 tCO2/d 12 (only membrane system)
Although membrane systems require a significant membrane area, their physical footprint can be more compact compared to other CO2 capture technologies like solvent absorption systems.4
Environmental issues: Membrane disposal due to degradation over time.
ENGINEERING
Maturity: Commercial (TRL 9)2
Most companies offer membrane-based capture systems commercially.
(MTR has been awarded a full-scale FEED project for a 3 MtCO2/yr capture plant)
Retrofittability: Good1
Technology’s modularity makes it versatile, however, gas pretreatment and compression may be needed.
Scalability: High1
Well suited for capturing large amounts of CO2 from industrial point sources, considering its modular nature.
Process type: Solid stationary membrane-based without chemical reactions.
Deployment model: Centralized only.
Each membrane module separates CO2 from the feed gas.
Technology flexibility: Hybridization with other capture technologies is feasible. Membranes can be used to increase CO2 concentration for other technologies for cost-effective capture.
TECHNOLOGY PROVIDERS
- Polaris™ by MTR Carbon Capture, United States
- Separex™ by Honeywell, Belgium
- HISELECT® by Linde Engineering, Ireland
- Optiperm™ by Ardent Technologies, United States
- SEPURAN® by Evonik Industries, Germany
- MEDAL™ by Air Liquide, France
- HyCaps by CO2CRC, Australia (Hybrid with solvent absorption and membrane separation)
- Membrane capture by Cool Planet Technologies, United Kingdom
INNOVATIONS
Mixed Matrix Membranes (MMMs): These membranes combine polymer matrices with inorganic fillers like metal-organic frameworks (MOFs), zeolites, or carbon nanotubes to enhance selectivity and permeability.13
Membrane-cryogenic hybrid systems: This hybrid system combines membranes with cryogenic separation to achieve higher CO2 capture efficiency and low energy consumption. The CO2 concentration is increased by using membranes as a pretreatment step, followed by separation via phase change in a cryogenic unit.14
Surface-modified membranes: Membranes with surface modifications, such as grafted CO2-philic (CO2-attracting) polymer chains, to enhance separation performance.15
CONTACT INFO
Mohammed Khan (mohammednazeer.khan@vito.be)
Miet Van Dael (miet.vandael@vito.be)
ACKNOWLEDGEMENT
This infosheet was prepared as part of the MAP-IT CCU project funded by VLAIO (grant no. HBC.2023.0544).
REFERENCES
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9. Zanco SE, Pérez-Calvo JF, Gasós A, Cordiano B, Becattini V, Mazzotti M. Postcombustion CO2 Capture: A Comparative Techno-Economic Assessment of Three Technologies Using a Solvent, an Adsorbent, and a Membrane. ACS Eng Au. 2021;1(1):50-72.
10. Roussanaly S, Vitvarova M, Anantharaman R, et al. Techno-economic comparison of three technologies for pre-combustion CO2 capture from a lignite-fired IGCC. Front Chem Sci Eng. 2020;14(3):436-452.
11. Menmuir D, Berry K. Next Generation Carbon Capture Technology Technoeconomic Analysis.; 2022.
12. Kulkarni S, Hasse D, Tranier JP, Corson E, Brumback J, Sanders E. CO2 CAPTURE BY SUB-AMBIENT MEMBRANE OPERATION. In: DOE NETLCO2 Capture Technology Meeting. ; 2012.
13. Katare A, Kumar S, Kundu S, Sharma S, Kundu LM, Mandal B. Mixed Matrix Membranes for Carbon Capture and Sequestration: Challenges and Scope. ACS Omega. 2023;8(20):17511-17522.
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15. Qi R, Li Z, Zhang H, et al. CO2 capture performance of ceramic membrane with superhydrophobic modification based on deposited SiO2 particles. Energy. 2023;283:129202.