Enhancing the Production of Phenolic Monomers from Reductive Catalytic Fractionation of Biomass over Catalyst of Ni–N-Doped Carbon

Phenolic monomers and polysaccharides from the reductive catalytic fractionation of biomass are extremely important precursors for producing chemicals and liquid fuels instead of excessive consumption of fossil fuels. In this work, a novel Ni–N-doped catalyst (Ni/Cf) prepared by the metal and bacterial residue carbon was employed for promoting the production of phenolic monomers. The several key parameters such as reaction temperature, pressure, time, gas types, catalyst types, and catalyst carriers were systematically optimized. The experimental results demonstrated that the lignin-derived phenolic monomer (LDPM) yield of 45.2 wt % and holocellulose retention rate of 96.0% were obtained by the birch RCF over Ni/Cf accompanied by the optimal reaction conditions of 220 °C, 3 h, and 2 MPa H2. The LDPM yield of birch over Ni/Cf was about 5.4 times and 3.1 times higher than that of Ni/Cf-u and Cf, respectively, and even better than Ni/AC, Ru/C, and Pd/C. The characterization analyses exhibited that the Ni–N-doped catalyst contained large specific surface areas, small particle sizes, microporous structures, and medium acid sites while increasing the electron transfer and interaction among C–O–N–Ni. These key factors jointly realized the efficient depolymerization of lignin into phenolic monomers and high-retention holocellulose.