We conducted nonisothermal fast hydrothermal liquefaction (HTL) of soy protein isolate (SPI) for batch holding times of 10-300 s and at temperatures up to 500 °C. The SPI solids rapidly formed water-soluble products, some of which subsequently formed biocrude. The highest biocrude yields (38-40 wt %) were obtained within 45-120 s, at which times the reactor temperatures had reached 375-435 °C. The highest recovery of nitrogen in the aqueous-phase products (80% of that present in SPI) occurred prior to formation of high biocrude yields. Ammonia formation was significant when the hydrothermal reaction medium reached supercritical conditions; over 50% of the atomic N appeared as ammonia under such conditions. We deduced the reaction pathways and developed a kinetic model from the experimental data. The reaction network includes two types of aqueous-phase products formed during HTL of protein. The first type arises directly from the SPI and the second arise from biocrude. The model accurately correlated the product yields under the fast HTL experimental conditions studied, and it accurately predicted the yields of product fractions from isothermal HTL of SPI at 300 and 350 °C.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Chemical Engineering(all)
- Renewable Energy, Sustainability and the Environment