Pyrolysis of brown coals. 3. Effect of cation content on the gaseous products containing oxygen from Yallourn coal

✍ Scribed by Harry N.S. Schafer

• Publisher: Elsevier Science
• Year: 1980
• Tongue: English
• Weight: 919 KB
• Volume: 59
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(80)90212-4

✦ Synopsis

A study has been made of the evolution of water, carbon dioxide and carbon monoxide during the pyrolysis of Australian Yallourn brown coal, and of the way in which the evolution is influenced by exchange of the carboxyl groups in the coal with magnesium and barium cations, Virtually all the oxygen in the coal can be removed as carbon dioxide, water and carbon monoxide with the greatest rate of loss occurring at 300, 356 and 500 to 600°C respectively. Increasing levels of cation alter the proportion of the volatile constituents but not the total amount of volatile matter evolved. Increased evolution of oxygen as carbon dioxide from a magnesium-form coal over that from acid-form coal is accompanied by a decrease in the amount evolved as water and carbon monoxide. Barium-form coals, however, show an increase in the amount of carbon monoxide evolved as the cation content increases. This is due in part to reactions involving the nitrogen gas used to provide a non-oxidizing atmosphere during pyrolysis. These reactions do not occur with magnesium-form coals. The amount of char formed by pyrolysis is the same for different levels of cation exchanged on the carboxyl groups. The results support conclusions that the carboxyl groups in a brown coal are associated with other oxygen groups, and that the mode of decomposition of the groups in this association (including carboxyl) is altered by the exchange of the carboxyl groups with cation.