Abstract:
The catalytic performance of three LaBO
3 perovskites including LaCoO
3, LaFeO
3 and LaNiO
3 in the liquefaction of lignin was investigate through a series of experimental characterization methods such as GC-MS, FT-IR and elemental analysis as well as DFT calculation. The effects of reaction time, temperature, catalyst amount and B cation on the lignin conversion, bio-oil yield and products distribution were considered. The results indicate that all three perovskite catalysts can promote the liquefaction of lignin to produce aromatic compounds; among them, LaCoO
3 shows the highest catalytic performance, following by LaNiO
3 and LaFeO
3. In particular, by using 5% LaCoO
3, the bio-oil yield achieves 67.20% after reaction at 180 °C for 60 min, whilst the relative content of mono-aromatic compounds reaches 89.59%. The adsorption of oxygen atoms on the LaBO
3 crystal surface conduces to the decrease of bond dissociation energy for lignin (LaCoO
3 shows the moderate redox capacity and greatest adsorption energy), whilst the loose and porous morphology can effectively promote the fracture of C−C and C
Ar−OCH
3 of lignin. All these contribute to the macromolecular depolymerization and demethoxylation reaction, producing high value-added compounds such as phenol.