Estimation of fuel properties for the heavy fraction of biomass pyrolysis oil consisting of proposed structures for pyrolytic lignin and humins

Authors: Terrell, Evan

Submitted to: Energies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2024
Publication Date: 4/24/2024
Citation: Terrell, E. 2024. Estimation of fuel properties for the heavy fraction of biomass pyrolysis oil consisting of proposed structures for pyrolytic lignin and humins. Energies. 17(9). Article 2011. https://doi.org/10.3390/en17092011.
DOI: https://doi.org/10.3390/en17092011

Interpretive Summary: Creating new products from renewable, biomass-based resources presents several challenges related to their characterization in the laboratory. Many of the technologies that currently exist for the production of fuels and/or chemicals from biomass give us complicated mixtures of products made up of a variety of molecules. Because of this complexity and the general lack of purity resulting from a biomass conversion process, designing experiments to measure interesting properties of these products is very difficult. This paper in particular is interested in the thermodynamic fuel properties of biomass conversion products. A new and improved method to estimate these fuel parameters in a computational way is introduced here. The goal of this work is to allow researchers to adapt this computational approach to their own systems and datasets, allowing for more flexibility in the application of the proposed method. There is also good opportunity to extend the analysis presented here to the computation of other interesting properties, not limited only to fuels. By using computers to understand our systems in a hypothetical way at low cost, more expensive experimental work can be better targeted at the things that are most interesting or show the most promise for further engineering development.

Technical Abstract: The organic component of biomass pyrolysis oils is composed of a light fraction (C2-C4 volatiles, sugar- and lignin-derived monomers) and a less polar heavy fraction (pyrolytic lignin/humins, greater than approximately 200 g/mol). Importantly, this heavy fraction can account for roughly one-third to one-half of the total pyrolysis oil. While the composition and characteristics of the light fraction are generally well understood, research is still needed for characterization of the heavy fraction. Some important thermodynamic fuel properties of this fraction are the heat of combustion, normal boiling point, heat of vaporization, and flash point, which are estimated in this work with regularized regression and empirical correlations. The quantification of these properties has implications on downstream utilization, particularly in the context of co-processing bio-oils with plastic and coal liquefaction products and/or crude petroleum. Finally, challenges and opportunities for (experimental) work are discussed for the advancement of sustainable valorization of biomass pyrolysis oils.