Catalytic conversion of lignin to aromatic monomers via heterostructured N-doped carbon encapsulated highly dispersed and ultrasmall MoC nanoparticles

The selective cleavage of C-O is facing a challenge in lignin depolymerization for producing aromatic monomers. Hence, N-doped carbon supported highly dispersed and ultrasmall MoC nanoparticles were prepared via a two-stage pyrolysis process using a mixture of glucose, ammonium molybdate and melamine for the conversion of lignin into aromatic monomers. A series of MoC/NC-x catalysts were prepared by varying the Mo:C weight ration among which the optimal MoC/NC catalyst showed the best hydrogenolysis performance. The real birch lignin could be completely converted at 280 ℃ after 4 h with 26.1 wt% aromatic monomers. The N-doped carbon was not only used as support to immobilized MoC nanoparticles, but also affecting the pore properties and metal-support interaction. Experimental and theoretical results reveal N can modulate the orbital structure of Mo to promote H₂ activation. Moreover, the pyridinic N contributes to the highest adsorption energy for 2-phenoxy-1-phenethanol and the disassociation of C_alkyl-O bond is significantly reduced on MoC/NC. This work provides a promising approach for the conversion of lignin to produce aromatic monomers with general applicability.