(453b) Reaction Mechanism of Catalytic Oxidative Depolymerization of Cellulosic Biomass

While biomass recalcitrance is one of the biggest challenges in biofuel industry, Nature has the key to unlock this puzzle. When a plant grows, the cell wall undergoes re-structuring. Recent biological studies found that hydroxyl radical (•OH), a very short-lived and strongly oxidative radical, is harnessed by the growing plant cells to loosen their cell walls by nonenzymatically cleaving the wall polysaccharides, although the physiological significance of this loosening mechanism is unclear. This nonenzymatic process sheds light on developing chemical oxidation methods for biomass deconstruction under mild reaction conditions. We are developing cost competitive catalytic biomass deconstruction strategies using aqueous phase partial oxidation (APPO) for releasing platform intermediates from solid biomass with a focus on the production of organic acid streams that can be readily upgraded and converted to commodity chemicals or infrastructure compatible liquid hydrocarbon fuels. The reaction mechanism of the APPO process has been investigated. A free radical route is presented to interpret the pathway of cleaving cellulosic biomass via the APPO process and the functionalities of oxidation catalysts are correlated to the reaction mechanism. By understanding the reaction mechanism, we are able to optimizing the catalytic system to realize high yield of the organic acids and to manipulate the selectivity of the APPO process.