Biocrude Production from Fast and Isothermal Hydrothermal Liquefaction of Chitin

We conducted isothermal and fast hydrothermal liquefaction (HTL) of chitin and determined the effects of temperature, holding time, and chitin wt % loading on product fraction yields and biocrude quality. Increasing the chitin loading from 1 to 15 wt % during isothermal HTL at 350 °C decreased the biocrude yield from 22 wt % to 10 wt %, increased the solids yield from 4 wt % to 16 wt %, and increased the nitrogen content in the biocrude. Increasing the chitin loading during fast HTL at a 500 °C set point temperature for 1 min, however, resulted in little variation in the biocrude and solids yields but again increased the nitrogen content. Fast HTL at this condition resulted in higher biocrude yields and higher energy recovery than did isothermal HTL under all tested chitin loadings. Fast HTL provides the opportunity to process chitin at high loadings (15 wt %) and achieve the highest available biocrude yields and energy recovery in the biocrude. Thermogravimetric analysis indicated a higher fraction of heavy components in the biocrude from isothermal HTL of chitin than from fast HTL. Ketones were abundant in the biocrude from isothermal HTL, and the biocrude from fast HTL was rich in nitrogen-containing compounds.