Integration of Ru/C and base for reductive catalytic fractionation of triploid poplar

Lignin, which is the most recalcitrant component of lignocellulosic biomass, is also the most abundant renewable aromatic resource. Herein, reductive treatment of triploid poplar sawdust by the integration of catalytic Ru/C and a base, which afforded high yields of phenolic monomers from the lignin component and a solid carbohydrate pulp, is reported. The introduction of Cs2CO3 led to the generation of C2 side-chained phenols through the cleavage of Cβ–O and Cβ–Cγ bonds in β–O–4 units in addition to C3 side-chained phenols; the relationship between C2 and C3 was dependent on the base dosage. The reaction conditions, including base species, temperature, time, and H2 pressure, were optimized in terms of phenolic product distribution, delignification degree, and carbohydrate retention. The carbohydrate pulps generated from reductive catalytic fractionation in the presence of Cs2CO3 were more amenable to enzymatic hydrolysis, indicating that this treatment of biomass constituted the fractionation of biomass components together with the breakdown of biomass recalcitrance.