Experimental study and process evaluation of a graded utilization strategy for woody biomass: Integration of reductive catalytic fractionation, hydrodeoxygenation, and catalytic pyrolysis

Complete conversion of lignocellulose into fuels and chemicals is significant yet challenging. This study proposes a novel graded utilization strategy for woody biomass, where reductive catalytic fractionation is followed by mild bio-oil hydrodeoxygenation for hydrocarbons generation and solid residue pyrolysis for alternative fuels and furfural production. Roles of metal-loaded alumina catalysts in H2-free reductive catalytic fractionation were clarified, achieving aromatic monomer yields of ∼39 wt%. Hexane pre-extraction of monomers before mild hydrodeoxygenation over Ru/Nb2O5 increased the hydrocarbon yield by 25 % relative to direct hydrodeoxygenation of crude aromatic bio-oils. Holocellulose-rich residues underwent catalytic pyrolysis using the same NiMo/Al2O3. Consequently, 10 %, 8 %, and 9 % of feedstock carbon are retained as hydrocarbons, furfural compounds, and other alternative fuels, respectively. Increasing ideal products yield and reducing solvent loading can significantly enhance system energy recovery. The estimated minimum fuel selling price aligns with the average retail gasoline price and could drop to $2.10 per gallon with an optimized solvent-to-biomass ratio. Meanwhile, the environmental benefits are substantial, not only reducing GHG emissions but also preventing burden shifting to other categories. This strategy offers a new pathway for co-producing fuels and chemicals from woody biomass, with future efforts needed to drive technological breakthroughs and mitigate commercialization risks.