Pyrolysis of dealkaline lignin to phenols by loading grinding beads in a rotary kiln reactor

The pyrolysis of dealkaline lignin to phenols was performed in a rotary kiln reactor using grinding beads as filler. The effects of pyrolysis temperature and the amount and material of grinding beads on the liquid yield and composition were investigated. The results showed that the use of the rotary kiln reactor loaded with grinding beads could improve the efficiency of lignin pyrolysis. Temperature had a considerable influence on the pyrolysis process. The maximum liquid yield of 52.10 % was obtained at 500 degrees C and carrier gas flow rate of 300 mL min-1. Compared with other grinding beads, gamma-alumina spheres could result in higher liquid yield and selectivity for guaiacols and alkylphenols. The liquid yield increased significantly with the use of grinding beads and increased with the increase in the number of grinding beads. However, both liquid yield and selectivity for guaiacol decreased when the volume ratio of grinding beads to reaction chamber increased from 1:2-2:3. The present study confirms the facilitative effect of grinding beads on the pyrolysis reaction, with the maximum increase of 86.87 % liquid yield and 12.58 % selectivity for guaiacol and alkyl phenols.