Kinetic Modeling of Dilute Acid Flowthrough Pretreatment of Poplar Wood

Dilute acid flowthrough pretreatment has been proven as effective approach to dissolve biomass with high sugar and lignin recovery. However, low sugar concentration resulted from the relatively low solid to liquid ratio employed still retards its application compared with conventional batch system. In this study, removal of xylan, lignin, and cellulose from poplar by dilute acid (0.05% (w/w) H₂SO₄) flowthrough pretreatment were found significantly enhanced when operation temperature was raised from 200°C to 240°C. The observed increases in whole biomass removal correlated with temperature, flow rate, biomass particle size, and solid loading are inconsistent with predictions by widely used first order kinetic models. Thus, a new model was established to investigate whether incorporation of mass transfer into the kinetic models could explain hydrolysis of whole biomass and individual components, including hemicellulose, lignin, and cellulose, on a more consistent basis. New findings provide more in-depth understanding on the dilute acid flowthrough pretreatment and new perspective of the reaction design for higher sugars concentration and low molecular weight lignin recovery.