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Study on the thermal degradation behaviors and kinetics of alkali lignin for production of phenolic-rich bio-oil using TGA–FTIR and Py–GC/MS

2015; Elsevier BV; Volume: 117; Linguagem: Inglês

10.1016/j.jaap.2015.12.007

1873-250X

Zhongqing Ma, Qingfeng Sun, Jiewang Ye, Qiufang Yao, Chao Zhao,

Biochemical and biochemical processes

Alkali lignin, an aromatic polymer extracted from soda pulping black liquor, is considered to be a potential source of phenolic-rich bio-oil using pyrolysis technology. This paper investigated the pyrolysis behaviors and kinetics of alkali lignin using thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TGA–FTIR) and pyrolyzer coupled with gas chromatography/mass spectrometer (Py–GC/MS). Results showed that the pyrolysis process of alkali lignin consisted of the three stages: drying stage, fast degradation stage and slow degradation stage. The weight loss rate reached its maximum value of 0.2448 mass%/°C at the temperature of 327 °C. The aromatics (at 1512 cm−1) and phenols (at 1261 cm−1) were the dominant volatile components according the FTIR spectrum. As the conversion rate increased from 0.05 to 0.9, the activation energy estimated from Flynn-Wall-Ozawa (FWO) method, was raised from 124 to 721 kJ mol−1. The phenolic compounds, namely guaiacol type (G-), the phenol type (P-), the syringol type (S-), and the catechol type (C-) were the main products from Py–GC/MS experiment. The total phenols and the G-type phenols reached their maximum contents of 78% and 63.43% at 500 °C, respectively. The content of S-type phenols decreased from 17.63% to 10.2% as the temperature increasing from 400 °C to 700 °C, while the contents of P-type and C-type phenols increased from 0.81% to 8.16% and 0.12% to 3.11%, respectively.