Solvent-thermal degradation of waste lignin over Ni-based catalysts in the presence of homogeneous acids.

Lignin was degraded to monomers and oligomers by thermochemical method. The yield and quality of degraded oil were different under different amount of solvents,homogeneous acids,and Ni-based catalysts. The results showed that the co-solvent of methanol and water promote the degradation of lignin. The residue yield decreased to 14. 9% with the oil product yield increased to 44. 1% in water / methanol / formic acid solvent. The addition of homogeneous acids( HCl and H3PO4) and heterogeneous catalysts( Ni and Ni / SiA l) not only improves the degradation of raw material,but also inhibits the condensation of degraded products. The obtained oils mainly contain monomers and oligomers. Ni / SiA l catalyzes the reforming of unsaturated aliphatic hydrocarbons and reduces oxygenic functional groups at the same time. This significantly decreases the yield of oil. Good oil quality with considerable oil yield( 41. 7%) was obtained under Ni catalyst.