Hot water flowthrough pretreatment removes hemicellulose as well as lignin from the biomass,  providing a unique opportunity to examine the dynamic deconstruction pattern of various components, including lignin, and hemicellose etc. Efficient hot water flowthrough pretreatment ensures high hemicellulose and lignin removal, and very high yield in sequential enzymatic hydrolysis that are vital to the economic viability of biomass conversion. More importantly, it is believed that solubility of higher molecular weight hemicellulose-lignin oligomers could play an important role in explaining why the performance of flowthrough systems differs from conventional batch approaches.

In the presentation we will show results from a number of studies using  flowthrough pretreatment of corn stover with hot water  under varying  temperature (160-220°C), time (0-120min), and flowrates (1-50mL/min) to understand the influence on lignin and hemicellulose removal into the hydrolyzate on further processing of the resulting pretreated biomass material. The dynamic characteristics of hemicellulose, lignin and their complex in the hydrolyzate during pretreatment, including compositions, structural features and solubility will be discussed. Finally we will present a model using kinetic data comparing conventional kinetic behavior versus that by dissolution and solubility limits with reaction and mass transfer effects. In addition, an analog of lignin-hemicellulose complex was also employed in this study to verify the kinetic model developed. Our model was found to be useful for providing insights into the pretreatment mechanism during thermal conversion of biomass.