Evaluation of pyrolysis characteristics and product distribution of black liquor using Py-GC/MS and down tube reactor: Comparison with lignin

In this study, the pyrolysis behaviors, kinetics and product distribution of black liquor solid (BLS) and precipitated lignin (PL) were studied by TGA, Py-GC/MS and a homemade down tube reactor. Compared with PL, the pyrolysis process of BLS was more complex and the residue was lower based on TG/DTG analysis. The average activation energy of BLS (440 - 456 KJ/mol) calculated by three model-free methods were higher than that of PL (293 - 339 KJ/mol). Py-GC/MS analysis showed that the total content of aromatic monomers in BLS bio-oil products was 26.02 - 26.50% (750 - 850 ?C), while it was 57.86 - 66.58% in PL bio-oil products. Moreover, BLS obtained a maximum aromatic hydrocarbon content of 90.15% (950 ?C) through down tube reactor pyrolysis, while it was 81.38% for PL. The alkali catalysis of the inorganic salt in BLS promoted the removal of phenolic hydroxyl groups.

Automated summary

In this study, the pyrolysis behaviors, kinetics, and product distribution of black liquor solid (BLS) and precipitated lignin (PL) were investigated. Results showed that BLS exhibited a more complex pyrolysis process with lower residue and higher activation energy compared to PL. BLS also had lower content of aromatic monomers in bio-oil products. Furthermore, alkali catalysis in BLS promoted the removal of phenolic hydroxyl groups, leading to differences in product distribution between BLS and PL.