(383b) Estimation of Biomass Pyrolysis Oil Oligomer Properties through Analysis with High Resolution Mass Spectrometry Coupled with Reaction Modeling

The oligomeric fraction of biomass pyrolysis oil makes up a significant component of pyrolysis products, comprising the majority of the overall liquid product mass. These high molecular weight molecules present an interesting and important engineering challenge regarding the characterization and final valorization of liquid products from biomass pyrolysis. In order to more fully understand the nature of the pyrolysis oil oligomeric fraction, it is necessary to estimate the structures of the molecules comprising this fraction.

In this presentation, we will use results from high-resolution FT-ICR MS analysis of bio-oils coupled with simple combinatoric modeling to simulate pyrolysis fragmentation to propose molecular structures for abundant bio-oil oligomers. The fragmentation modeling is used to build up a library of oligomers to which FT-ICR MS-detected peaks can be matched. Once these molecular structures have been proposed, then their properties can be estimated (via group contribution methods and other possible correlations). Some of these properties include normal boiling point, heat of vaporization, and solubility parameters.

At present, a total of 50 structures have been assigned to detected MS peaks with high abundance among three contrasting bio-oils. Importantly, we show that these structures can be reached beginning from unmodified cellulose-derived oligomers, while at the same time producing H₂O, CO and C2-C3 light volatile organics. Figure 1 depicts a potential fragmentation pathway that yields C₈H₁₄O₇, one of the top-abundance peaks in FT-ICR MS analysis.

Based on the resulting structure, it is then possible to estimate properties of the molecule with the prescribed structure. For example, cellobiosan (another abundant bio-oil product) has been estimated to have normal boiling point of 555 C and total solubility parameter of 41 MPa^1/2. Ongoing work will extend this property prediction analysis to further assigned/proposed oligomeric structures corresponding to high-abundance peaks detected in FT-ICR MS analysis of bio-oil.