(117g) Kinetic Study of the Hydrothermal Liquefaction of Microalgae

Hydrothermal liquefaction can convert wet algal biomass, at elevated temperatures and pressures, into an energy-dense biocrude without the need for dewatering the algae or extracting the lipids. Presently, there has been limited study to determine the global kinetics of the hydrothermal liquefaction of microalgae. We present results from a kinetic study using microalgae feedstocks with varying carbohydrate, lipid, and protein concentrations. We determined reaction pathways and calculated activation energies and frequency factors from empirical data. We analyzed all of the liquefaction products to obtain data for mass and elemental balances. The elemental analyses were used specifically to examine elemental partitioning amongst the products and how they relate to kinetic parameters. We propose that with the global kinetic analysis we are able to model the outcome of hydrothermal liquefaction based on the biochemical and elemental profile of the feedstock. In addition to kinetic studies, we also examined how processing conditions affect the yield and composition of all of the liquefaction products, not just the biocrude. We completed a systematic study of the processing conditions related to microalgae liquefaction. We examined the effects of biomass preservation, reaction atmosphere, and biomass loading. Our results show that varying these effects does not affect the product yield or composition significantly.