(390b) Structural and Chemical Changes in Plant Cell Walls during Early Stages of Thermal Deconstruction

Volatile products from lignocellulosic biomass thermal deconstruction processes—combustion, gasification, fast pyrolysis, and solvent liquefaction—have been well characterized, but the solid and liquid phase reactions that occur in the early stages of decomposition are largely unknown. Here we analyze the initial solid phase biomass thermal deconstruction reactions in planta and with high particle heating rates, creating the most accurate investigation to date of how these processes occur. Using a variety of instrumentation, we quantify the extent and relative rates of deconstruction, demonstrating that biopolymers resist the thermally energetic conditions to differing degrees, even when ensconced in biomass cell walls. Hemicellulose and the more frangible lignin components decompose and volatilize more readily than cellulose; this outcome temporarily enriches biomass with cellulose. These chemical changes additionally manifest in larger cell wall structure and mechanical property transformations. In all, our investigation concludes that these solid phase reactions strongly influence the production rates of volatile species and will require additional study before these processes can be modeled precisely or desired product yields potentially improved.