Self-ignition and mechanisms of interaction of coal with oxygen at low temperatures. 3. Changes in the composition of coal heated in air at 60 °C

✍ Scribed by Vassil N. Marinov

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 661 KB
• Volume: 56
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(77)90138-7

✦ Synopsis

The gradual changes in weight, in elementary composition, in content of oxygen functional groups and in spin concentration have been established for samples of black coal, brown coal and lignite heated in air for a maximum of 1200 h. An intensive oxidative dehydrogenation was found to occur after more than 300 h oxidation. The process was preceded by a decrease in weight and in oxygen content; its start was found to coincide with a sharp increase in the alcoholic content and in coal ability to exchange hydrogen with calcium acetate, and its rate was found to diminish simultaneously with this ability. The acidity ascribed to phenols decreases gradually but it was found to increase at the end of the experiment. A decrease in ignition temperature was established for oxidized black coal, as well as a change in the composition of low-molecular-weight hydrocarbons evolved during the subsequent gradual heating in air. Some of the changes in the composition during coal oxidation may be explained by acid catalysis.