Thermal Decomposition Characteristics of Chinese Fir

Chinese fir (Cunninghamia lanceolata) has great potential as a future bio-energy resource in China. Thermogravimetry (TG) was used to investigate the thermal decomposition process of Chinese fir, including heartwood and sapwood. The Flynn-Wall-Ozawa and Coats-Redfern (modified) methods were used to determine the activation energy. A combination of TG and Fourier transform infrared spectrometry (TG-FTIR) was used to analyze the pyrolysis products. The TG curve indicated that the degradation processes of heartwood and sapwood were similar, but the degradation temperature of heartwood was lower than that of sapwood. The main decomposition occurred within the temperature range of 500 K to 660 K, and over 70% of the mass was degraded. The activation energy of Chinese fir with heartwood and sapwood changed slightly with an increase in conversion rate from 10 to 70. That of heartwood and sapwood was 155.38 to 158.37 KJ/mol and 155.93 to 180.04 KJ/mol, respectively, using the Flynn-Wall-Ozawa method. TG-FTIR analysis showed that the main pyrolysis products included absorbed water (H2O), methane gas (CH4), carbon dioxide (CO2), carbon monoxide (CO), acids and aldehydes, nitrogen dioxide (NO2), nitric oxide (NO), and ammonia gas (NH3). The results from this study are helpful for designing a better bio-energy manufacturing process for Chinese fir via gasification and pyrolysis methods.