Bimetallic ruthenium- and zinc-doped beta zeolite for efficiently depolymerizing Kraft lignin

The efficient depolymerization of Kraft lignin is essential for comprehensive utilization of biomass. Herein, we prepared a bimetallic Ru/Zn@Beta zeolite catalyst using a co-impregnation synthesis approach that combined zeolite and metal. The bimetallic Ru/Zn@Beta catalyst efficiently depolymerized Kraft lignin, which has been credited as the electrostatic interaction of Zn Lewis acid sites and Ru hydrogen binding sites on Beta zeolite. Catalytic hydrodeoxygenation of Ru/Zn(1:2)@Beta catalyst for 9 h at 290 °C produced a maximum ethyl acetate soluble product yield of 96% with G-type selectivity reaching 74.7%. In these circumstances, compared to Kraft lignin, which produces a heating value of 26.0 MJ/kg, liquefied lignin possesses a much superior heating value of 30.39 MJ/kg. This research has established a paradigm for increasing lignin depolymerization efficiency by coupling Lewis acid and hydrogenation catalysts.