Chemicals from Coking Metallurgical Coal
Most of the chemicals derived from coal come from by-products produced during the coking process. Coal is used to make coke to make steel. Coke gas (also called foul gas) contains coke tars, ammonia, and light oils. Tars are recovered and used to make tar derivatives. Ammonia is recovered as an aqueous solution or as an ammonium sulfate salt. Napthalene, an important poly-cyclic aromatic chemical is also distilled from coke gas and tars. Light oils from the coke gas may be processed to recover benzene, tolulene, xylene, and solvent naptha (e.g., RTI, 2008). A wide array of chemicals and materials are made from these coke by-products.
Coal-tar pitch is the residue left from coal tar distillation. One of the products derived from coal-tar pitch is activated carbons. Activated carbons are man-made carbons produced to have high internal surface areas so that they have very high micro-porosity. Because of their large pore volumes, they are useful materials in commercial and industrial adsorbents. Activated carbons are mostly produced from charcoal, but can also be produced from coal-tar pitch.
Another product, which can be derived from coal-tar pitch are carbon fibers. These fibers are used in the aerospace industry and in a variety of electronic applications. There are many different types of carbon fibers and many sources for carbon in carbon fibers, but a minor source is coal-tar pitch.
For more information about activated carbon and carbon fiber research at the University of Kentucky go to the CAER webpage.
Another interesting material that can be made from coking byproducts is carbon nanotubes. Carbon nanotubes are cylindrical carbon molecules, which are only a single carbon-atom thick. Although incredibly thin, they can be made with very large length-to-diameter ratios. Carbon nanotubes have exceptional strength, thermal, and electronic properties, which makes them very valuable in the nano-technological, electronical, and optical industries, as well as being used as strengthening fibers in an increasing number of products. Most nanotubes are generated from graphites and other high-purity carbon sources, but fullerenes produced from coal coking tars can also be used. Fullerenes are clusters of 60 carbon atoms (C60), arranged in essentially a ball shape, like a soccer ball. The Center for Applied Energy at the University of Kentucky has been actively involved in the research of carbon nanotubes from coal and coal byproducts. For more information see the CAER website.
Other Uses of Coal:
- Coal for Electricity Generation
- Coal to Make Coke and Steel
- Coal for Industry and Residential Markets
- Rare Earth Elements from Coal
References for Chemicals from Coking
- Batchelder, H.R., 1970, Chemicals from coal: Industrial and Engineering Chemical Product Research and Development, v. 9, no. 3, p. 341-343.
- Derbyshire, F., Jagtoyen, M., Fei, Y.Q. and Kimber, G., 1994, The production of materials and chemicals from coal: Preprints Of Papers-American Chemical Society Division Fuel Chemistry, v. 39, p.113-113.
- Derbyshire, F.J., Jagtoyen, M., McEnaney, B., Sethuraman, A.R., Stencel, J.M., Taulbee, D. and Thwaites, M.W., 1991. The production of activated carbons from coals by chemical activation: American Chemical Society, Division Fuel Chemistry v. 36, no. 3, p.1072-1080.
- Gibson, J., and Gregory, D.H., 1971, Carbonisation of coal: Mills and Boon Limited, London, Monograph Chemical Engineering, v. 4, 71 p.
- Granda, M., Blanco, C., Alvarez, P., Patrick, J.W., and Menendez, R., 2013, Chemicals from coal coking: Chemical Reviews, v. 114, p. 1608-1636.
- Mahler, B.J., and Van Metre, P.C., 2011, Coal-tar-based pavement sealcoat, polycyclic aromatic hydrocarbons (PAHs), and environmental health: U.S. Geological Survey, Fact sheet, http://pubs.usgs.gov/fs/2011/3010/pdf/fs2011-3010.pdf
- McEnaney, B., 1999, Structure and bonding in carbon materials, in Burchell, T.D. (ed.), Carbon materials for advanced technologies: Pergamon Press, New York, p. 1-34.
- Moothi, K., Iyuke, S.E., Meyyappan, M. and Falcon, R., 2012, Coal as a carbon source for carbon nanotube synthesis: Carbon, v. 50, no. 8, p. 2679-2690.
- Pang, L.S.K., Vassallo, A.M., and Wilson, M.A., 1991, Fullerenes from coal: Nature, v. 352, p. 480.
- Pang, L.S., Vassallo, A.M. and Wilson, M.A., 1992. Coal as a feedstock for fullerene production and purification: American Chemical Society, Division of Fuel Chemistry, Proceedings, v. 37, p.564-567.
- Research Triangle Institute (RTI), 1998, Coke ovens: Industry profile: Draft report prepared for the U.S. Environmental Protection Agency, Contract No. 68-D4-0099, varied pagination, https://www3.epa.gov/ttnecas1/regdata/IPs/Coke_IP.pdf.
Schobert, H.H., and Song, C., 2002, Chemicals and materials from coal in the 21st century: Fuel, v. 81, p. 15-32.
- Song, C. and Schobert, H.H., 1996, Non-fuel uses of coals and synthesis of chemicals and materials: Fuel, v. 75, no. 6, p.724-736.
- Stansberry, P.G., Zondlo, J.W., and Stiller, A.H., 1999, Coal-derived carbons, in Burchell, T.D. (ed.), Carbon materials for advanced technologies: Pergamon Press, New York, p. 205-234.
- Sun, J., Rood, M.J., Rostam-Abadi, M. and Lizzio, A.A., 1996, Natural gas storage with activated carbon from a bituminous coal: Gas separation and purification, v. 10, no. 2, p.91-96.
- RTI International, 2008, Emission factor documentation for AP-42, Section 12.2, Coke Production, Final Report: Report prepared for U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. May 2008, EPA Contract No. EP-D-06-118, varied pagination.
- U.S. Department of Health and Human Services, 2016, Household product database; USDHHS website, https://hpd.nlm.nih.gov/cgi-bin/household/search?tbl=TblChemicals&queryx=50-00-0, accessed 2016.
- U.S. National Energy Technology Laboratory, 2016, Types of coal-derived chemicals: U.S. Department of Energy, NETL website, http://www.netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/coal-derived-chem, accessed 2016.
- Weisenberger, M., no date, Activated carbons: University of Kentucky, Center for Applied Energy Research, Tech Facts, 2 p, http://www.caer.uky.edu/techfacts/TechFacts-CM-Activated-Carbons.pdf
- Yu, J., Lucas, J., Strezov, V. and Wall, T., 2003, Coal and carbon nanotube production: Fuel, v. 82, no. 15, p. 2025-2032
- Zoeller, J.R., 2009, Eastman Chemical Company’s “Chemicals from Coal” program: the first quarter century: Catalysis Today, v. 140, nos. 3-4, p. 118-126.