Influence of functional groups on the oxidation of aromatic structures
Energy Process Engineering
Final Report Abstract
In regards of a permanent increase in the global energy demand, a major challenge of the century is the reduction in fossil fuel combustion. Improving combustion systems and replacing conventional fuels by sustainable energy carriers can help in achieving this goal. In this context bio-based octane improvers, i.e. oxygenated aromatics, can play an important role. These compounds can be produced from uneatable lignin and their physico-chemical properties make them ideal fuel blending components with improved anti-knock behavior. In addition, oxygenated aromatics play also an important role in the combustion of solid biomass, e.g., during energy production but also wild fires and safety applications. Motivated by this need for an understanding of the combustion behaviour of lignin-based oxygenated structures, this project investigated the oxidation of representative molecules by means of experimental investigation of ignition delay times (IDT) in shock tube (ST) and rapid compression machine (RCM), quantum mechanical calculations of critical thermodynamic data and reactions, and kinetic modelling. In particular, the oxygenated aromatics anisole, phenol, the three methylanisole isomers, benzaldehyde and benzylalcohol have been investigated experimentally in a pressure range of 10 - 40 bar, at equivalence ratios within 0.5 - 2.0 and at temperatures ranging from approximately 800 - 1200 K. All these components show an Arrhenius type ignition behaviour and are therefore candidates for improving the octane rating of conventional fuels with phenol being the least reactive and benzyl alcohol the most reactive component. The analysis of the developed kinetic models revealed that the reactivity of the investigated molecules is dictated by the functional side groups. Thereby the relevant reaction pathways are strongly interlinked by the shared phenoxy submechanism. Overall, the project provided important insights into the combustion chemistry of oxygenated aromatics which will help to understand the combustion behaviour of lignin-based fuels or the combustion of wooden biomass in bio-reactors or even wild fires in future.
Publications
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Characterization of oxygenated aromatics in a rapid compression machine, Bunsentagung 2018, 10th - 12th May 2018, Hannover, Germany
R.D. Büttgen & K.A. Heufer
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Combustion of oxygenated aromatic hydrocarbons - A RCM study of Benzene, Toluene, Phenol and Anisole -, 9th European Combustion Meeting, 14th – 17th April 2019, Lisboa, Portugal
R.D. Büttgen, L. Pratali Maffei, M. Pelucchi, T. Faravellil, A. Frassoldati & K.A. Heufer
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An experimental, theoretical and kinetic modelling study on the reactivity of a lignin model compound anisole under engine-relevant conditions. Fuel, 269, 117190.
Büttgen, R.D.; Tian, M.; Fenard, Y.; Minwegen, H.; Boot, M.D. & Heufer, K.A.
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Rate constants for H-atom abstraction reactions from mono-aromatic hydrocarbons by H, CH3, OH and 3O2: A systematic theoretical investigation. Combustion and Flame, 257, 112421.
Pratali, Maffei Luna; Pelucchi, Matteo; Büttgen, René D.; Heufer, Karl A.; Faravelli, Tiziano & Cavallotti, Carlo
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Auto-ignition characteristics of oxygenated aromatic compounds: Benzyl alcohol, benzaldehyde, and phenol. Proceedings of the Combustion Institute, 40(1-4), 105252.
Heufer, Karl Alexander; Büttgen, Rene Daniel; Pratali, Maffei Luna & Pelucchi, Matteo
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Relative reactivity of methyl anisole isomers: An experimental and kinetic modelling study. Combustion and Flame, 266, 113533.
Heufer, Karl Alexander; Büttgen, Rene Daniel; Pratali, Maffei Luna & Pelucchi, Matteo
