Lignin Deconstruction Understood Through Coupled Structural and Kinetic ModelsPublic Deposited
The use of biomass as a feedstock for fuels and chemicals has been a long-standing challenge and opportunity for the chemical and basic materials industries. In order to unlock the value of biomass, it is necessary to first deconstruct its structural polymers, cellulose, hemicellulose, and lignin, into low molecular weight species that are subsequently upgraded. Of the three constituents, lignin is one of the most promising but also least valorized, in part because of its complex structure, but also because of the complex product distribution arising upon deconstruction. In this dissertation, the two types of deconstruction chemistry studied are dilute acid hydrolysis (acidolysis) and fast pyrolysis. A structural model that incorporates four of the major structural characteristics of lignin is presented. In order to understand the chemistry of lignin acidolysis, a microkinetic model of the major ether linkage type in lignin is constructed. A pathways-level description of fast pyrolysis is developed, and this chemical model is coupled with the structural model to simulate the intrinsic kinetics of lignin fast pyrolysis. For each model described, comparison is made to recent experimental data, and also for each model, novel predictions are made. Finally, key model design decisions are reviewed and discussed in light of the suggested future research efforts.