Oxidation of Coal. [100 References]. PDF Download

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Book Description
Certain organic compounds are oxidized more readily than others. The ease with which an organic substance will oxidize depends on the functional groups present in the molecule. Oxidation of coal is affected by incorporation of oxygen functional groups, such as the peroxide, the hydroxyl, the aldehyde, the carbonyl, the carboxyl, the ether linkage, and the methoxyl groups. Once oxygen has been combined with an organic molecule, further oxidation may occur more readily. Compounds with oxygen functional groups attached are more susceptible to further oxidation than their progenitors. For example, alcohol and acetaldehyde oxidize more readily than ethane, phenol and naphthol more easily than benzene and naphthalene, and benzaldehyde more readily than toluene. Saturated and purely aromatic hydrocarbons are more difficult to oxidize than their derivatives containing oxygen functional groups. The formation of peroxide appears to be one of the initial steps of coal oxidation; it can lead then to the formation of other oxygen functional groups. The weathering of coal increases the concentration of the oxygen functional groups, and some reduction of carbon content results, technological quality of coal changes, water content increases, and alkali-soluble products similar to the humic acids form, as well as water-soluble lower molecular weight acids. In the early stages of oxidation oxygen is being added to the coal bulk composition and water is lost, while during the later stages of humification of coal, CO/sub 2/, CO, and H/sub 2/O evolve. The oxidation proceeds along the periphery of the macromolecule clusters in coal and affects the C--C bonds, rupturing the aromatic rings. Further oxidation reactions are described.