Less than one percent of the total coal mined in the United States is used to make chemicals from coal gasification, but the technology provides important products that consumers use every day. Gasification is different than combustion of coal to make heat for electric power. Instead of burning the coal, the feed coal is combined with water in a slurry. The slurry is heated into steam, and oxygen is added in a thermal-chemical process which breaks down the matrix molecules in the coal. The produced "syngas" consists mainly of carbon monoxide (CO), hydrogen (H2), water vapor (H2O), and some other minor gases. These gases can then be separated through chemical processes and used as chemical feedstocks or products. Coal gasification can also be used to provide electricity in Integrated Gasification Combined Cycle (IGCC) plants.

A good example of coal gasification used to produce chemicals from coal is the Eastman Chemical plant in Kingsport, Tennessee. At the Kingsport plant, coal or a mixture of coal and pet-coke is gasified and particulate material is removed from the resulting syngas stream. Next, the syngas is purified through the removal of mercury (Hg), sulfuric acids (H2S), and carbon dioxide (CO2). The sulfuric acids are treated to form raw sulfur (S). Next, the cleaned syngas is separated into carbon monoxide (CO) and hydrogen (H2), which by themselves, are chemical products. Further treatment results in methanol (CH3OH), which is the source material for many important chemicals. One of those chemicals is methyl acetate, which is used in the production of acetic acid and acetic anhydride. The main function of the Kingsport plant is the production of acetic anhydride, which is used to make photographic film, synthetic textiles, and other products (Trapp, 2001; Eastman Chemical, 2003).

Schematic diagram showing how various chemicals are produced from coal gasification (based on diagrams in Trapp, 2001).
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Table of products produced from coal gasification (data from Eastman Chemical Co., 2013; National Energy Technology Laboratory, and U.S. Department of Health and Human Services)

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Other Uses of Coal:

References for Chemicals from Coal Gasification

 

 

Last Modified on 2017-03-30
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