Highly efficient hydrogenolysis of lignin into monophenol over an atomically dispersed platinum catalyst

The cleavage of C-O bonds in lignin depolymerization was made great progress, but the cleavage of C-C bonds still face challenges. An atomically dispersed Pt loading of 3.30 wt% catalyst, Pt/Nb2WO8, was prepared by the pyrolysis of ammonium niobate oxalate and sodium tungstate dihydrate with ammonium carbonate as the template. It is found that the decomposition of ammonium carbonate and the doping of W species promoted the orderly growth of niobium tungsten oxide crystals with oxygen vacancy and the formation of a regular porous structure, which was conducive to the dispersion of Pt particles. Pt/Nb2WO8 efficiently cleaved β-O-4, β-1, α-1 and 5–5 bonds. The yield of aromatic monomers for lignin depolymerization reached as high as 49.08% over Pt/Nb2WO8. Experiments combined with density functional theory calculations revealed that the excellent activity of the Pt/Nb2WO8 catalyst was attributed to the cooperation of atomically dispersed Pt sites and support near the interface. The atomically dispersed Pt species enhanced the dissociation of H2, and the Nb2WO8 support with abundant B acid sites provided by W doping and oxygen vacancies activated C-O and C-C bonds of lignin in the reaction. The homogeneous cleavage of C-C bonds dominated the deconstruction of β-1, α-1 and 5–5 bonds. This methodology opens up a facile strategy for the design of atomically dispersed Pt/Nb2WO8 catalyst with higher Pt loading and excellent catalytic activity to the cleavage of both C-O and C-C bonds in lignin.