Chemical Characterization of Biomass Pyrolysis Oil Facilitated by Aerosolization and Size Separation

Abstract Bio-oils are a promising renewable and carbon-neutral hydrocarbon material that can become a new energy source. Bio-oil mixtures have complex multi-component composition consisting of the pyrolysis products of cellulose, hemicellulose, and lignin of various molecular sizes with a range of highly oxygenated functional groups. Chemical characterization of bio-oil components is therefore necessary to inform the upgrading process of bio-oil and improve its commercial viability. We utilize aerosol technology to facilitate characterization of bio-oil components resulting in compositional differences specific to its volatility-separated fractions. We aerosolize bio-oil mixture, followed by size separation and collection of obtained particles using a cascade impactor, where the collected particles are exposed to sequentially reduced pressures at each of the impaction stages. We characterize components of the impactor separated bio-oil fractions using high-resolution mass spectrometry equipped with interchangeable electrospray ionization and dopant-assisted atmospheric pressure photoionization sources. Through examination of the detected chemical species in each of the separated fractions and assessment of their physiochemical properties, we identify a range of fuel-like aliphatic species with low O/C ratio and low viscosity in the most volatile fraction. The less volatile fractions contained progressively higher portions of more viscous species containing lignin and sugars moieties with characteristic high O/C values. We show that the impactor-based separation of bio-oil fractions facilitates comprehensive characterization of its components with varying fuel viability, capable of guiding upgrading processes. Copyright © 2023 American Association for Aerosol Research Graphical Abstract