Ni₁₂P₅/P-N-C Derived from Natural Single-Celled Chlorella for Catalytic Depolymerization of Lignin into Monophenols

Lignin is exceptionally abundant in nature and is regarded as a renewable, cheap, and environmentally friendly resource for the manufacture of aromatic chemicals. A novel Ni₁₂P₅/P-N-C catalyst for catalytic hydrogenolysis of lignin was synthesized. The catalysts were prepared by simple impregnation and carbonization using the nonprecious metal Ni taken up by the cell wall of Chlorella in Ni(NO₃)₂ solution. There were only two steps in this process, making the whole process very simple, efficient, and economical. Ni₁₂P₅ was uniformly distributed in the catalyst. During the hydrogenolysis of lignin, after 4 h reaction at 270 °C, the yield of bio-oil reached 65.26%, the yield of monomer reached 9.60%, and the selectivity to alkylphenol reached 76.15%. The mixed solvent of ethanol/isopropanol (1:1, v/v) is used as the solvent for the hydrogenolysis of lignin, which not only had excellent hydrogen transferability but also improved the yield of bio-oil, inhibiting the generation of char. No external hydrogen was used, thus avoiding safety issues in hydrogen transport and storage.