Hydrothermal liquefaction of polysaccharide feedstocks with heterogeneous catalysts

Hydrothermal liquefaction (HTL) of starch, cellulose, pectin, and chitin with Pd/C, Co-Mo/γ-Al₂O₃, and zeolite was investigated at 320 °C for 30 min. Using Co-Mo/γ-Al₂O₃ at 5 wt% loading led to the highest biocrude yields from starch (25 wt%) and cellulose (23 wt%). The yields from cellulose are more than twice those from noncatalytic HTL (11 wt%). Co-Mo/γ-Al₂O₃ was also the only catalyst (25 wt% loading) to increase biocrude yields (by 1.6 – 2.6 wt%) from HTL of chitin and pectin. The biocrudes were characterized by elemental analysis, TGA, FT-IR and GC–MS. Catalytic HTL with Co-Mo/γ-Al₂O₃ had little effect on the elemental composition of the biocrudes. The presence of Co-Mo/γ-Al₂O₃ increased the low-boiling portion of biocrude from<30% to over 50% for HTL of starch. Finally, a component additivity model that accurately predicts biocrude yields from catalytic HTL of a mixture is presented.