| Pyrolysis of lignocellulosic biomass could become a significant source of renewable chemicals and fuels in the near future. In addition to bio-oil production, fast pyrolysis of biomass produces significant quantities of synthesis gases and char. Decades of classical research on pyrolysis of lignocellulosic biomass has not yet produced a generalized formalism for design and prediction of reactor performance. Plagued by the limitations of experimental techniques such as thermogravimetric analysis (TGA) and extremely fast heating rates and low residence times to achieve high conversion to useful liquid products, researchers are now turning to molecular modeling to gain insights. While there is considerable on-going molecular-scale modeling in the area of lignocellulosic biomass, the majority focuses on discovering specific conversion pathways.;This work, however, endeavors to utilize molecular-scale modeling to enable the development of meso- to micro-scale simulations that connect with relevant micro-structural and kinetic aspects of biomass pyrolysis. Biovia Material Studio 5.5 and 7.0 were used to perform molecular dynamics simulations using the molecular mechanics force field, PCFF. In this study, diffusion coefficients for CO2 in crystalline and amorphous cellulose were estimated at different temperatures. Morphological changes in cellulose and whole biomass were also studied in an effort to discern relevant mechanisms associated with microstructural changes caused by thermal depolymerization. The results from this study illustrates how a new era of molecular-scale modeling-driven inquiry is beginning to shape the diverse research landscape and influence the description of how cellulose and associated hemicellulose and lignin depolymerize to form the many hundreds of potential products of pyrolysis. |
