| Abstrakt: |
The potential of biomass pyrolysis to mitigate climate change needs to be reconsidered. Thermogravimetric pyrolysis of beech, oak, and spruce wood was carried out to evaluate the course of pyrolysis, the conditions affecting the biochar yield, its fixed carbon content and yield, specific surface area, and gas phase composition. The thermal degradation of the main wood components occurred at the same temperatures with a comparable gas composition (30% H2O, 22% CO, 17% CO2 and 31% VOC + H2) determined by mass spectrometry. Several organic compounds were also confirmed. Lower temperatures, heating rates, and isothermal times favored higher biochar yields while lowering fixed carbon contents. Oak (> 24%) showed higher carbon sequestration potential than beech and spruce (about 21%). To obtain high specific surface area values (> 200 m2 g−1), pyrolysis should be operated in the temperature range of 500–700 °C. The isothermal time is not necessary at temperatures of 600 or 700 °C, but at 500 °C, it is essential that the biochar develops an internal surface. To achieve a high yield of quality biochar with high specific surface area and fixed carbon content, pyrolysis should be carried out at a low heating rate (4 K min−1) and in the temperature range of 500–700 °C, with the necessary isothermal stage at 500 °C. Using pyrolysis instead of combustion, CO2 emissions are reduced by almost half due to carbon sequestration through biochar formation. To obtain the same power output as in the case of combustion, virtually twice the biomass amount must be pyrolyzed. [ABSTRACT FROM AUTHOR] |
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