Materials for Manipulating the Composition of Biomass Pyrolysis Vapors

Upgrading the chemical species generated from the fast pyrolysis of biomass either through post-condensation or in situ catalytic conversions has received a significant amount of attention. Recently, conversion strategies have increasingly focused on ex situ conversion of the pyrolysis vapors prior to their condensation. Many of these studies have concentrated on model compound studies. While this is a reasonable starting point, the compositional complexity of the pyrolysis vapors coupled with relatively low abundance of any single species creates a significant gap between model compounds and realistic vapor streams, which will likely impact what constitutes an effective catalytic material. Within the real streams important targets are: 1) carbon-efficient conversions; 2) significant reduction in acid content and 3) selective removal of oxygen. Presented will be our development and use of modified CaCO₃ to selectively remove organic acid species from real pyrolysis vapors. Specific surface modifications of the CaCO₃ were required to achieve the specificity. Also discussed will be the use of MoO₃ with low pressure hydrogen to effectively remove oxygen from real biomass pyrolysis vapor streams.