Understanding the synergistic effect during co-liquefaction of cellulose and hemicellulose (xylan) in subcritical water

Hydrothermal liquefaction (HTL) is a promising technology for conversion lignocellulosic biomass into bio-oil, however, the interactions between biomass components are not well understood. Microcrystalline cellulose (MCC) and xylan were used as model components for cellulose and hemicellulose in the HTL process considering the influence of temperature, reaction time and solvent to solid ratio. Synergistic interactions occurring between MCC and xylan could enhance both the bio-oil and heavy bio-oil (HBO) yields, and MCC contributed more to the oil yield. In terms of HBO yield, it was in the order of MCC (20.8%) > MCC-xylan (19.4%) > xylan (17.5%). Regarding to the bio-oil chemical compositions, interactions promoted the formation of 5-hydroxymethylfurfural and inhibited some carbonyl groups. Higher temperatures led to lower H/C and O/C of the HBO from MCC-xylan, which also increased the HHV of HBO. The synergies identified in this work provide new insight into potential interactions between biomass components.