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UBC Theses and Dissertations

Multiple reaction solid state kinetic parameter determination and its application to woody biomass Mochulski, David


The economic problem of sustainable and environmentally responsible energy production has prompted research into a number of potential alternatives to fossil fuels. Biomass gasification has been identified as one such alternative, but incomplete characterization of the process has hindered development. This thesis addresses the problem of predicting reaction rate behavior in the case of woody biomass and aids in identifying optimal feedstock composition. Black cottonwood (Populus trichocarpa) and Lodgepole pine (Pinus contorta) samples were characterized in terms of their primary component composition (lignin, cellulose, and hemicellulose) and then subjected to gasification experiments. This consisted of pyrolysis, under a nitrogen atmosphere, and then gasification, under a dry air atmosphere, while undergoing a linear temperature program in a thermogravimetric analyzer (TGA). Inspection of the experimental data indicated the presence of three simultaneous reactions. The data was then analyzed to recover the isoconversional activation energy trend, pre-exponential factors, and reaction mechanisms. Results indicated that the contributions of the three reactions did not correspond directly to lignin, cellulose, and hemicellulose contents, but, in the case of nitrogen pyrolysis, could be predicted by the knowledge of these components. Regarding air gasification, no significant correlations between reaction rate behavior and primary wood component fraction were found. Qualitatively, the work showed that the rate at which pyrolysis occurs is increased by high cellulose and hemicellulose contents, and decreased by large lignin contents. A detailed kinetic model describing both Poplar and Lodgepole pine pyrolysis behavior was also recovered and is reported in the body of the thesis.

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