Separation of Co2 From Flue Gases by Carbon-Multiwall Carbon Nanotube Membranes

Canonical Monte Carlo (CMC) simulations were carried out to investigate the behavior of CO(2) and N(2) mixtures upon adsorption on single walled carbon nanotubes (CNTs). In the simulation, all the particle-particle interactions between CO(2), N and C were modeled using Lennard-Jones (LJ) potential. To provide deep insight into the effect of pore width, temperature, pressure and bulk composition on the adsorption behavior of CO(2) /N(2) mixtures, five different CNTs [(6,6), (7,7), (8,8) (9,9) and (10,10) CNT] with diameters ranging from 0.807 to 1.35 nm, three temperatures (300 323 and 343 K), six pressures (0.15, 2, 4, 6, 8 and 10 MPa), and three bulk mole compositions of carbon dioxide (0.3 0.5 and 0.7) were tested. The results from all the simulation conditions investigated in this work show that CNTs preferentially adsorb carbon dioxide relative to nitrogen in a binary mixture. The results are consistent with the hypothesis that stronger interaction of one component with the nanotube surface results in a higher adsorption capacity compared to the other component. An optimized pore size of D = 8.07 nm corresponding to (6, 6) CNT, at T = 300 K and P = 0.15 MPa at a bulk mole composition of y(CO2) =0.3 was identified in which carbon nanotubes demonstrate the greatest selectivity for separation of carbon dioxide relative to nitrogen. In addition, it is worth pointing out that, under similar simulation conditions, CNTs exhibit higher selectivity compared to other carbon-based materials [carbon membrane polyimide (PI) and PI/multi-wall carbon nanotubes (MWCNTs)] for CO(2) adsorption. As a prototype, the selectivity of an equimolar mixture of CO(2) /N(2) for adsorption on (6, 6) CNTs at 300 K and 0.15 MPa reaches 9.68, which is considerably larger than that reported in carbon membrane. Therefore, it can be concluded that carbon nanotubes can act as a capable adsorbent for adsorption/desorption of CO(2) in comparison with other carbon-based materials in the literature.

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Separation and Capture of CO₂from Large Stationary Sources and Sequestration in Geological Formations—Coalbeds and Deep Saline Aquifers

White

Strazisar

Granite

et al. 2003

Journal of the Air & Waste Management Association

691

479

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The topic of global warming as a result of increased atmospheric CO2 concentration is arguably the most important environmental issue that the world faces today. It is a global problem that will need to be solved on a global level. The link between anthropogenic emissions of CO2 with increased atmospheric CO2 levels and, in turn, with increased global temperatures has been well established and accepted by the world. International organizations such as the United Nations Framework Convention on Climate Change (UNFCCC) and the Intergovernmental Panel on Climate Change (IPCC) have been formed to address this issue. Three options are being explored to stabilize atmospheric levels of greenhouse gases (GHGs) and global temperatures without severely and negatively impacting standard of living: (1) increasing energy efficiency, (2) switching to less carbon-intensive sources of energy, and (3) carbon sequestration. To be successful, all three options must be used in concert. The third option is the subject of this review. Specifically, this review will cover the capture and geologic sequestration of CO2 generated from large point sources, namely fossil-fuel-fired power gasification plants. Sequestration of CO2 in geological formations is necessary to meet the President's Global Climate Change Initiative target of an 18% reduction in GHG intensity by 2012. Further, the best strategy to stabilize the atmospheric concentration of CO2 results from a multifaceted approach where sequestration of CO2 into geological formations is combined with increased efficiency in electric power generation and utilization, increased conservation, increased use of lower carbon-intensity fuels, and increased use of nuclear energy and renewables. This review covers the separation and capture of CO2 from both flue gas and fuel gas using wet scrubbing technologies, dry regenerable sorbents, membranes, cryogenics, pressure and temperature swing adsorption, and other advanced concepts. Existing commercial CO2 capture facilities at electric power-generating stations based on the use of monoethanolamine are described, as is the Rectisol process used by Dakota Gasification to separate and capture CO2 from a coal gasifier. Two technologies for storage of the captured CO2 are reviewed--sequestration in deep unmineable coalbeds with concomitant recovery of CH4 and sequestration in deep saline aquifers. Key issues for both of these techniques include estimating the potential storage capacity, the storage integrity, and the physical and chemical processes that are initiated by injecting CO2 underground. Recent studies using computer modeling as well as laboratory and field experimentation are presented here. In addition, several projects have been initiated in which CO2 is injected into a deep coal seam or saline aquifer. The current status of several such projects is discussed. Included is a commercial-scale project in which a million tons of CO2 are injected annually into an aquifer under the North Sea in Norway. The review makes the case that this can al...

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Separation of Co2 From Flue Gases by Carbon-Multiwall Carbon Nanotube Membranes

Cited by 4 publications

References 9 publications

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Modeling the adsorptive selectivity of carbon nanotubes for effective separation of CO2/N2 mixtures

Separation and Capture of CO₂from Large Stationary Sources and Sequestration in Geological Formations—Coalbeds and Deep Saline Aquifers

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Separation of Co2 From Flue Gases by Carbon-Multiwall Carbon Nanotube Membranes

Cited by 4 publications

References 9 publications

Bibliography

Bibliography

Modeling the adsorptive selectivity of carbon nanotubes for effective separation of CO2/N2 mixtures

Separation and Capture of CO2from Large Stationary Sources and Sequestration in Geological Formations—Coalbeds and Deep Saline Aquifers

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Product

Resources

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Separation and Capture of CO₂from Large Stationary Sources and Sequestration in Geological Formations—Coalbeds and Deep Saline Aquifers