Detailed compositional analysis and structural investigation of a bio-oil from microwave pyrolysis of kraft lignin

This work investigates composition and structure of a bio-oil produced form microwave pyrolysis of kraft lignin at different conditions. The studied variables were content of microwave-absorber (20-40 wt%) and nominal setting power (1.5-2.7 kW). The measured temperatures after applying the selected conditions for 800s were 900, 980,1065, 1150, and 1240 K. The obtained yields of the aqueous phase, oil phase, non-condensable gas, and solid were 17-21%, 15-20%, 21-27%, and 32-40%, respectively. To investigate the extracted chemicals quantitatively and qualitatively, GC-MS and GC-FID were performed on the liquid samples. In addition, P-31 and C-13 NMR spectroscopy were implemented to provide detailed structure information for the whole oil phase and the raw material. Furthermore, different degradation pathways were suggested to represent the thermal-decompotition of lignin bonds. (C) 2014 Elsevier B.V. All rights reserved.