W_B is the weight of lipid before reaction (mg),

Oxidation of biodiesel (BD) obtained from the decomposition of biomass can damage the fuel injection and engine parts during its use as a fuel. The excess heating of vegetable oils can also cause polymerization of the biodiesel. The extent of BD oxidation depends on its fatty acid composition. In this study, an accelerated oxidation test of BDs at 95 °C was investigated according to ASTM D 2274 by applying a long-term storage test for 16 weeks. The density, viscosity, and total acid number (TAN) of BDs increased because of the accelerated oxidation. Furthermore, the contents of unsaturated fatty acid methyl esters (FAMEs), C18:2 ME, and C18:3 ME in BDs decreased due to the accelerated oxidation. The ¹H-nuclear magnetic resonance spectrum of BDs that were obtained from the accelerated high temperature oxidation at 180 °C for 72 h differed from that of fresh BDs. The mass spectrum obtained from the analysis of the model FAME, linoleic acid (C18:2) methyl ester, which was oxidized at high temperature, indicated the formation of dimers and epoxy dimers of linoleic acid (C18:2) methyl ester by a Diels-Alder reaction.

The aviation industry has set ambitious goals for reducing carbon emissions, with the International Civil Aviation Organization targeting net-zero carbon emissions by 2050. Bio-jet fuel is expected to play a crucial role in achieving this target, and the demand for bio-jet fuel is projected to rapidly increase. Bio-oil from fast pyrolysis of lignin, such as waste wood, is considered a promising alternative for production of bio-jet fuel through processes such as hydrodeoxygenation. In this study, the physical properties and compositions of bio-jet fuel produced from wood-derived pyrolysis bio-oil blended with petroleum-based jet fuel as well as their changes during 16 weeks storage were investigated. Consistently, 0%, 10%, 50%, and 100% blended bio-jet fuels were prepared. After 16 weeks of aging, the total acid number of the all-blended bio-jet fuel showed a sharp increase from 12 weeks, reaching over 0.1 mg KOH/g. Additionally, kinematic viscosity showed a steady increase over 16 weeks whereas oxidative stability decreased by approximately 20% at 16 weeks for the 100% bio-jet fuel alone. The final boiling point increased by up to 20% in higher blends of bio-jet fuel and the average molecular weight increased. Bio-jet fuel has a high olefin content, which can further increase during storage, leading to a decrease in the combustion characteristics. This study suggests that using up to 10% the bio-jet fuel in aircraft is safe considering storage stability, but further research is required to confirm this finding.

We can prevent climate change by reducing greenhouse gas (GHG) emissions caused by fossil fuel usage through introducing alternative fuels such as bio-oil. The fast pyrolysis process used for wood materials has recently gained substantial attention as an approach to produce bio-oil worldwide and in Korea as well. Bio-oil from fast pyrolysis contains highly oxygenated compounds and phenolics, thereby requiring upgrading processes, such as deoxygenation and condensation, for high-end use. To determine an efficient upgrading method for fast pyrolysis bio-oil (FPBO), one needs to elucidate its composition and classify it into chemical groups. We analyzed the composition of fractionized FPBO toward high-end use. FPBO was separated into two layers by adding distilled water: (a) the water-soluble phase, and (b) the oil phase, whereas liquid-liquid extraction and multi-step separation were applied for fractionization, respectively. The fractions were obtained, and their chemical groups were analyzed by gas chromatography time-of-flight mass spectrometry (GC×GC-TOF/MS). The water phase was separated into two fractions and classified into the main chemical groups of phenolics (9%) and heterocyclics (31%). The oil phase, which was separated into four fractions, was classified into the main chemical groups of phenolics (32%) and heterocyclics (23%). Our findings can help to upgrade products for high-end use.