@misc{12823,
  abstract     = {{The energy crisis and dependence on fossil fuels forces societies to develop alternative pathways to secure energy supplies. Therefore, non‐fossil fuels such as biofuels and e‐fuels can help counteract the resulting demand for existing combustion engines. However, biofuels, like biodiesel, have disadvantages in terms of oxidation stability. In general, aging of biodiesel is a complex mechanism due to interaction of various components. In order to develop an ideal fuel, the mechanism must be understood in full detail. In this work, an attempt is made to simplify the system by using methyl oleate as a biodiesel model component. In addition, other fuel components of interest such as alcohols and their respective acids help to clarify the aging mechanism. This work used isopropylidene glycerol (solketal) as the main alcohol, 1‐octanol and octanoic acid. A holistic biodiesel aging scheme was developed by using generated data and evaluating the role of acids. They epoxidize unsaturated fatty acid via Prileschajev reactions. In addition, the role of epoxides in oligomerization reactions is confirmed. Moreover, the alcohols show that the suppression of oligomerization can be achieved by the reaction with methyl oleate. The alcohol‐dependent aging products were determined by quadrupole time‐of‐flight (Q‐TOF) mass spectrometry.}},
  author       = {{Türck, Julian and Schmitt, Fabian and Anthofer, Lukas and Türck, Ralf and Ruck, Wolfgang and Krahl, Jürgen}},
  booktitle    = {{  ChemSusChem : chemistry & sustainability, energy & materials}},
  issn         = {{1864-564X}},
  keywords     = {{biodiesel aging, epoxide-dependent oligomerization, solketal, Prileschajew reaction}},
  number       = {{17}},
  publisher    = {{Wiley}},
  title        = {{{Extension of Biodiesel Aging Mechanism–the Role and Influence of Methyl Oleate and the Contribution of Alcohols Through the Use of Solketal}}},
  doi          = {{10.1002/cssc.202300263}},
  volume       = {{16}},
  year         = {{2023}},
}

@misc{12836,
  abstract     = {{The complexity of biodiesel aging has shown that the mechanism needs further research. The rate of aging product formation and associated interactions can help improve fuel quality. Since biodiesel is a multicomponent system and constant changes occur in the chemical environment, which interactions yield which products must be shown in more detail. Particularly under observation was the correlation between peroxides and epoxides. In addition, it is critical that the influence and interactions of new drop-in fuel candidates be investigated. In this work, the kinetics of the formation of aging products of methyl oleate (C18:1) are studied. The aim was to reduce the complexity in order to be able to make more precise and detailed statements about the mechanism. Ketones, acids, peroxide, and epoxide values were recorded. A distinction is made between pure methyl oleate and mixtures with 3 wt% isopropylidene glycerine (solketal). After solketal decomposed in the blends, the aging process showed changes. The influence of solketal resulted in a higher number of acids and epoxides over time. It implied that peroxides are not necessarily the precursor of epoxides. In summary, correlation and solketal’s influence showed that a sequence of aging products could be detected.}},
  author       = {{Türck, Julian and Schmitt, Fabian and Anthofer, Lukas and Lichtinger, Anne and Türck, Ralf and Ruck, Wolfgang and Krahl, Jürgen}},
  booktitle    = {{Energies : open-access journal of related scientific research, technology development and studies in policy and management}},
  issn         = {{1996-1073}},
  keywords     = {{oxidation kinetics, biodiesel aging, methyl oleate, solketal, alcohol influence, sequence of aging products}},
  number       = {{7}},
  publisher    = {{MDPI AG}},
  title        = {{{Oxidation Kinetics of Neat Methyl Oleate and as a Blend with Solketal}}},
  doi          = {{10.3390/en16073253}},
  volume       = {{16}},
  year         = {{2023}},
}

@misc{12829,
  abstract     = {{Due to the fact that modern diesel engines require very well-defined fuel properties to ensure high efficiency, low emissions and a long durability, the fuel properties and their determination methods have to be standardized. Most diesel fuel standards allow a certain volume fraction of biodiesel that can be blended to fossil diesel fuel. Biodiesel consists of saturated and unsaturated fatty acid methyl esters (FAME) which are more susceptible to oxidation compared to fossil diesel fuel. Oxidation products formed by autoxidative processes can lead to higher emissions, a higher corrosiveness, fuel filter blocking, clogging of fuel injectors, the formation of deposits in the entire fuel system and a decreasing lubricity [1]. Therefore, oxidation needs to be prevented by the addition of oxidation inhibitors. These antioxidants are consumed during storage, resulting in partial loss of their efficiency against oxidative stress. After this induction period all antioxidants have been consumed and harmful oxidation products can be formed. For the determination of the long-term storage stability of diesel fuels rapid oxidation stability test methods were developed and defined by standards. In Europe, the most important determination methods are the Rancimat method and the rapid small scale oxidation test (RSSOT). Both methods differ in the construction of the measurement device and various parameters. However, it is not clear whether the results of both methods can be correlated in general. Due to the importance of the oxidation stability, we here describe the results of a literature research that was carried out using 17 literature sources. Possible correlation factors between the Rancimat and the RSSOT method were analyzed, showing that a universal correlation cannot be found. In contrast, a comparison of individual series of measurement, e.g. with the same antioxidant at various concentrations, can show a good correlation between the methods.}},
  author       = {{Bär, Ferdinand and Knorr, Markus and Schröder, Olaf and Hopf, Henning and Garbe, Thomas and Krahl, Jürgen}},
  booktitle    = {{Fuel : the science and technology of fuel and energy}},
  issn         = {{1873-7153}},
  keywords     = {{Rancimat, PetroOxy, RSSOT, Biodiesel, Diesel, Fuel, Oxidation stability}},
  publisher    = {{Elsevier BV}},
  title        = {{{Rancimat vs. rapid small scale oxidation test (RSSOT) correlation analysis, based on a comprehensive study of literature}}},
  doi          = {{10.1016/j.fuel.2021.120160}},
  volume       = {{291}},
  year         = {{2021}},
}

@misc{12838,
  abstract     = {{The need for new bio based drop-in components for combustion engine fuels and the availability of sustainable glycerol from biodiesel production has focused attention on isopropylidene glycerol (solketal). The present study investigates the physical and chemical behavior of solketal in ternary blends with diesel fuel/biodiesel. Hydrotreated vegetable oil (HVO) was used as renewable non-polar aliphatic diesel fuel substitute in biodiesel/ solketal blends. HVO can be considered a prototype for other non-polar fuel components such as paraffinic fuel streams from Fischer-Tropsch or BtL processes. Surface tension, permittivity and aging behavior were analyzed. Furthermore, the cetane number (CN) and the viscosity was determined. Permittivity reflects the polarity of blends and their components with its change being an indicator of loss of physical and chemical stability. The antioxidant triphenyl phosphorothioate (TPPT) was also tested in some blends. The biodiesel blends B20, B30 and B40 enables single phased diesel fuel or HVO with varied solketal content (2 and 10%) at a constant biodiesel amount. No effect of solketal on fuel aging was observed. However, HVO-containing blends tend to lower the thermo-chemical stability relative to diesel fuel.}},
  author       = {{Türck, Julian and Singer, Anja and Lichtinger, Anne and Almaddad, Mohammad and Türck, Ralf and Jakob, Markus and Garbe, Thomas and Ruck, Wolfgang and Krahl, Jürgen}},
  booktitle    = {{Fuel : the science and technology of fuel and energy}},
  issn         = {{1873-7153}},
  keywords     = {{Solketal, Biodiesel, HVO, Diesel fuel, Miscibility, Fuel aging, Cetane Number}},
  publisher    = {{Elsevier BV}},
  title        = {{{Solketal as a renewable fuel component in ternary blends with biodiesel and diesel fuel or HVO and the impact on physical and chemical properties}}},
  doi          = {{10.1016/j.fuel.2021.122463}},
  volume       = {{310}},
  year         = {{2021}},
}