Hydrothermal Treatment of Protein, Polysaccharide, and Lipids Alone and in Mixtures

We subjected a set of model compounds (cornstarch and cellulose as model polysaccharides, soy protein and albumin as model proteins, sunflower oil and castor oil as model lipids) to the processing conditions and product recovery protocol commonly used for hydrothermal liquefaction (HTL) of algal biomass to make crude bio-oil. The model compounds were treated individually and in mixtures at 300 and 350 °C for batch holding time ranging from 10 min to 90 min. The model lipids produced the highest yield (>90 wt %) of biocrude (operationally defined as material soluble in dichloromethane), followed by the model proteins (∼30–35 wt %) and then the model polysaccharides (∼10–15 wt %). The production of biocrude at 350 °C occurred fully within the first 10 min of treatment, and the biocrude yield changed very little at longer times. Liquefaction at 350 °C and 60 min nearly doubled the biocrude yields from polysaccharides, relative to those obtained at 300 °C and 20 min. Otherwise, the yields from the different m...