Abstract
In order to realize a promissing disposal of solid wastes, especially for biomass and plastics, and the recovery of high value-added products, lignin (LG) and polyethylene (PE) were co-pyrolyzed with the addition of transition metals. Thermal behavior and kinetics of the mixtures affected by the type of transition metals (0.5 mmol/g Ni, Co, Fe and Mn), the concentration of Ni (0-1 mmol/g Ni), the ratio of LG to PE (4:1-1:4) and heating rate (10-40 degrees C/min) were investigated according to thermogravimetric analysis (TGA). It is found that the treatment of LG/PE with 0.5 mmol/g Ni, Co, Fe or Mn results in the decrease of the initial decomposition temperature of LG and PE in the mixture by 10-53 degrees C and 9-18 degrees C, respectively. According to the difference of weight loss (Delta W), the introduction of Fe and Mn has slight influences on the interaction between LG and PE while a negative effect of PE on the devolatilization of LG in LG/PE can be largely diminished with the involvement of Ni and Co. Kinetic analysis reveals that the pyrolysis of LG and PE can be well fitted by a single first order model reaction while two consecutive first order model reactions are needed to exactly describe the co-pyrolysis of LG/PE with or without transition metals. The E value of LG and PE in the mixture is reduced by 6.11-21.62 kJ/mol and 7.67-50.11 kJ/mol, respectively, when 0.5 mmol/g Ni, Co, Fe or Mn was involved. Moreover, the concentration of Ni, the ratio of LG to PE and the heating rate play important roles on the thermal behavior and kinetics of the copyrolysis of LG/PE. (C) 2019 Energy Institute. Published by Elsevier Ltd. All rights reserved.