In-Situ Reforming of Tar from the Rapid Pyrolysis of a Brown Coal over Char
Reforming of nascent tar from the rapid pyrolysis of a brown coal over char prepared from the same coal was studied at 750−900 °C. The reforming was very rapid and extensive, allowing only benzene (0.02% on a coal C basis), naphthalene (0.001%), and phenanthrene (0.0001%) to escape from the char bed...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
| Published: |
American Chemical Society
2010
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| Subjects: | |
| Online Access: | http://hdl.handle.net/20.500.11937/47733 |
| Summary: | Reforming of nascent tar from the rapid pyrolysis of a brown coal over char prepared from the same coal was studied at 750−900 °C. The reforming was very rapid and extensive, allowing only benzene (0.02% on a coal C basis), naphthalene (0.001%), and phenanthrene (0.0001%) to escape from the char bed at an empty-bed gas residence time of less than 170 ms and 900 °C, respectively. Reforming even at 750 °C converted 96% of heavy tar (boiling point temperature >336 °C) into noncondensable gases and coke deposit over the char. Decreasing conversion of the tar into coke with increasing temperature suggested that the tar was reformed in a sequence of coking and steam gasification of the coke rather than direct steam reforming over the char. The reforming at 900 °C gave a negative coke yield due to progress of coke/char gasification faster than the coke deposition. Results of this work thus showed a possibility of complete tar reforming by intensification of contact between the char and volatiles even in the absence of a catalyst. |
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