Capture of Carbon Dioxide

The overall sequestration process involves four steps  

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Linga, P. Kumar, R. Englezos P. (2007b). The clathrate hydrate process for post and pre combustion capture of carbon dioxide. J Hazardous Materials, revised submitted May 10, 2007... 

Gray ML, Hoffman JS, Hreha DC et al (2009) Parametric study of solid amine sorbents for the capture of carbon dioxide. Energ Fuel 23(10) 4840 1844... 

Dynamic Capture of Carbon Dioxide via Reversible Ammonium Carbamate Formation... 

As a consequence of this, there is now a major focus on the use of coal as a source for fuels and olefins. Coal has a far higher level of carbon than petroleum fuels and natural gas and this inevitably leads to higher emissions of carbon dioxide in the production of fuels and olefins. As a consequence there are research and development projects concerned with the capture of carbon dioxide from coal based operations and the geo-sequestration of the carbon dioxide. 

Capture of CO2 at concentrated sources is easier than capture from the environment, but it requires significant changes in the existing infrastructure. Furthermore, approximately half of all emissions arise from small, distributed sources. Many of these emitters are vehicles, for which capture on board is not practical. For small, mobile emitters, the subsequent capture of carbon dioxide from the air provides another alternative. 

Fig. 1 Capture of carbon dioxide by a 50 g/L solution of absorbent in a 500 ml batch absorber. The gas being treated was ambient air, at a carbon dioxide concentration of 403 pmoles/mole and a flow rate of 0.96 slpm. The fact that this absorbent can reduce CO2 levels to less than that of ambient air shows that a properly designed countercurrent scrubbing unit could use this solution to keep CO2 levels in a combustion gas stream from exceeding the normal levels present in the atmosphere. It should be noted that, under these conditions, the ability of pure water to absorb carbon dioxide was negligible.

The fact that a massive supply of coal still exists in this country argues for technologies that allow for more efficient use of coal and that bum coal with fewer emissions and less carbon dioxide. One of the technologies presently being pursued is to combine anaerobic hydrolysis of coal with the capture of carbon dioxide by calcium oxide. The thermodynamics of these combined processes indicate that coupling these reactions leads to a thermodynamically neutral overall reaction. 

Because of the growing importance of carbon dioxide sequestration, there is currently a lively debate as to whether future coal-fired power stations should be conventional pulverized fuel, oxy-fuel or gasification designs. This is by no means a straightforward choice and involves considerations of overall fuel efficiency, engineering complexity and capital and operating costs. In addition, there are many types of coal (anthracite, bituminous coal, brown coal) with possibly dissimilar impurity contents, each of which may dictate a different plant design. The jury is still out on whether future coal-fired power stations will employ post-combustion or pre-combustion capture of carbon dioxide this is a crucial issue to decide as the plants have a life of 40—50 years. 

The capture of carbon dioxide from streams of mixed gases and its subsequent indefinite storage. 

P.H.M. Feron and A.E. Jansen, Capture of carbon dioxide using membrane gas absorption and reuse in the horticultural industry. Energy Comers. Manage. 36 (1995) 411-414. 

A detailed comparison of the above two schemes is quite a complex exercise and goes beyond the scope of this study. The purpose of this paragraph is to provide a preliminary economic assessment of the use of membrane reactors to improve the IGCC process in terms of production of a fuel for electric generation and the capture of carbon dioxide. 

CCS involves the capture of carbon dioxide emissions from the source, followed by transportation to, and storage in, geological formations. Once the carbon has been captured, there are a number of storage options available. The carbon dioxide can be stored in deep saline aquifers or be used to assist in enhanced oil recovery and subsequent carbon dioxide storage. 

Capture of carbon dioxide from coal gasification is already achieved at low marginal cost in some plants. One (albeit where the high capital cost has been largely written off) is the Great Plains Synfuels Plant in North Dakota, where six million tons of lignite is gasified each year to produce clean synthetic natural gas. 

McDonald TM, Lee WR, Mason JA et ai (2012) Capture of carbon dioxide from air and flue gas in the alkylamine-appended metal-oiganic framework mmen-Mg2(dobpdc). J Am Chem... 

Lu H, Reddy EP, Smimiotis PG (2(X)6) Calcium oxide based sorbents for capture of carbon dioxide at high temperatures. J Ind Eng Chem 45 3944-3949... 

D. R. Paul, Y. P. Yampol skii, Gas Separation Membranes, Boca Raton, CRC Press (1994). C. E. Powell, G. G. Qiao, Polymeric CO2/N2 gas separation membranes for the capture of carbon dioxide from power plant flue gases, J. Membr. ScL, 279, 1 9 (2006). 

Schach, M., Schneider, R., Schramm, H. and Repke, J. (2010) Techno-economic analysis of postcombustion processes for the capture of carbon dioxide from power plant flue gas. Industrial and Engineering Chemistry Research, 49 (5), 2363-2370. 

Davison X, Thambimuthu K. Technologies for capture of carbon dioxide . Proceedings of GHGT-7, Vancouver, Canada, 2004. 

CO2 as a byproduct during the combustion of fuels in industrial plants and automobiles is a major contributor to global warming. Hence, the selective capture of carbon dioxide requires special attention from the scientific community. The principle sources of CO2 that cause harm to the environment are contaminated natural gas, containing a mixture of methane and CO2 (known as pre-combustion), and exhaust gas generated in industiy or from automobiles (post-combustion). Separate physical conditions are needed for CO2 capture from pre- and post-combustion mixtures, and a variety of porous polymer networks, both soluble and insoluble, have been involved in CO2 capture with consideration of their pore dimensions. " ... 

Adeyemo A, Kumar R, Linga P, Ripmeester J, Englezos P (2010) Capture of carbon dioxide from flue or fuel gas mixtures by clathrate crystallizatirai in a silica gel column. Int J Greenhouse Gas Control 4(3) 478-485... 

Babu P, Kumar R, Linga P (2013) Pre-combustion capture of carbon dioxide in a fixed bed reactor using the clathrate hydrate process. Energy 50 364-373... 

Gholinezhad J, Chapoy A, Tohidi B (2011) Separation and capture of carbon dioxide from CO2/H2 syngas mixture using semi-clathrate hydrates. Chem Eng Res Des 89(9) 1747-1751... 

Li X-S, Xia Z-M, Chen Z-Y, Wu H-J (2011) Precombustion capture of carbon dioxide and hydrogen with a one-stage hydrate/membrane process in the presence of tetra-n-butylammonium bromide (TBAB). Energy Fuels 25(3) 1302-1309... 

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