(264g) Multiscale Effects of Lignocellulose Bioconversion and Corresponding Process Intensification: From Nanoscale to System Scale

Zhao, X., Tsinghua University
Liu, D., Tsinghua University
Lignocellulosic biomass has attracted great interest as a renewable feedstock to produce biofuels, materials and chemicals in recent decades, due to the depletion of fossil fuels and increasing environment pollutions. However, because of the hierarchy nano- and ultrastructure of lignocellulose cell wall, as well as the heterogeneity of conversion system, the bioconversion efficiency of lignocellulose to fuel such as ethanol is still not high enough for a commercialization in an economical way. Here, we have analyzed the multiscale effects of lignocellulose bioconversion with regards to the substrate structure and the conversion system. We propose that the key issues related to cell wall structure limiting cellulose bioconversion majorly include the supramolecular structure of cellulose, ultrastructure of cell wall, as well as the inhomogeneity and diversity of the lignocellulosic biomass at the nano-, meso- and macro-scales, respectively. For the bioconversion system, the multiscale effects at least involve the molecular recognition of cellulose by cellulase, the interaction between cellulose surface and cellulase components, the permeation and diffusion of enzymes in the pores of cell wall, the rigorous kinetic modeling of biomass pretreatment and enzymatic saccharification, the high-solid effect of cellulose hydrolysis and the process integration to minimize energy consumption and production cost, from the nano to system scales. Our recent research progress on the understanding the multiscale effects of biomass structure and the corresponding process intensification strategies will be introduced. In more details, we have studied how hemicellulose and lignin limit the accessibility of cellulose, and found that strong interactive effects exited between hemicelluloses and lignin. To accurately determine cellulose accessibility, we developed a novel visualizable fusion protein probe to measure cellulose accessible surface area under wet state. We also proposed a novel kinetic model (potential degree of reaction model) to accurately describe the apparent kinetics of biomass pretreatment. These works can serve as a step for improving the efficiency of the lignocellulose bioconversion.