Reductive Catalytic Fractionation of Abies Wood into Bioliquids and Cellulose with Hydrogen in an Ethanol Medium over NiCuMo/SiO2 Catalyst

Abstract

Noble metal-based catalysts are widely used to intensify the processes of reductive fractionation of lignocellulose biomass. In the present investigation, we proposed for the first time using the inexpensive NiCuMo/SiO2 catalyst to replace Ru-, Pt-, and Pd-containing catalysts in the process of reductive fractionation of abies wood into bioliquids and cellulose products. The optimal conditions of abies wood hydrogenation were selected to provide the effective depolymerization of wood lignin (250 °C, 3 h, initial H2 pressure 4 MPa). The composition and structure of the liquid and solid products of wood hydrogenation were established. The NiCuMo/SiO2 catalyst increases the yield of bioliquids (from 36 to 42 wt%) and the content of alkyl derivatives of methoxyphenols, predominantly 4-propylguaiacol and 4-propanolguaiacol. A decrease in the molecular mass and polydispersity (from 1870 and 3.01 to 1370 Da and 2.66, respectively) of the liquid products and a threefold increase (from 9.7 to 36.8 wt%) in the contents of monomer and dimer phenol compounds were observed in the presence of the catalyst. The solid product of catalytic hydrogenation of abies wood contains up to 73.2 wt% of cellulose. The composition and structure of the solid product were established using IRS, XRD, elemental and chemical analysis. The data obtained show that the catalyst NiCuMo/SiO2 can successfully replace noble metal catalysts in the process of abies wood reductive fractionation into bioliquids and cellulose.