INFORM November/December 2025

18 • inform November/December 2025, Vol. 36 (10)

pound and simplified them into groups with distinct chemical functionality. Woody biomass has higher lignin content that translates into higher phenolic content in the bio-oils compared to corn stover and miscanthus bio-oils. Bio-oils from non-lignocellu losic feedstocks—municipal solid waste, biosolids, and plas tic—have noticeably different compositions compared to the biomass-derived bio-oils. Biosolids contain high nitrogen con tent compared to biomass and as a result its bio-oil contains a higher concentration of nitrogen-containing chemicals like pyr idines, pyrroles, and amines. Plastic pyrolysis bio-oil contains 100 percent hydrocarbons produced from polyethylene and polypropylene thermal decomposition. However, as noted, only 25-50 percent of bio-oil is vol atile enough to be analyzed directly by GC/MS. Therefore, researchers need complementary analytical methods to achieve a comprehensive molecular-level characterization of bio-oils. Fractionating bio-oils using different solvents reduces its chemical complexity by separating components into water soluble and solvent soluble aliquots (https://doi.org/10.1021/ acs.energyfuels.4c01959). Fortunately, a similar approach can be applied to bio-oils. Petroleomics was developed for understanding the molecular composition of petroleum crudes ( https://doi.org/10.1021/acs.energyfuels.3c02599). Advanced instrumentation, such as high field-Fourier trans form-ion cyclotron resonance-mass spectrometry (FT-ICR-MS),

assigns unique chemical formulas to the tens of thousands of mass spectral peaks associated with the volatile components and the ultracomplex, non-distillable components comprised of polyfunctional oxygenates. The FT-ICR-MS technique detects lignin and cellulose thermal decomposition fragments con taining up to 24 oxygen atoms (https://doi.org/10.1021/acs. energyfuels.4c05674). SUMMARY There are numerous pyrolysis technologies for converting biomass into liquid bio-oil intermediates. The feedstock, process, and process conditions impact the physical and chemical properties of bio-oils. The inherent complexity of bio-oils creates a significant challenge for achieving a com prehensive chemical characterization necessary to optimize refining and separation processes and develop commer cially viable applications for bio-oils. A detailed understand ing of bio-oil physical and chemical properties would de-risk their use in existing fuel refining and distribution infrastruc ture, as well as support development of new technologies and applications. David C. Dayton is a Senior Fellow at RTI International with 30 years of experience in biomass thermochemical conversion research and development involving biomass combustion, gasifi cation, and pyrolysis. He can be contacted at ddayton@rti.org.

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