Oxygenated biofuels are an alternative to drop-in hydrocarbon fuels sourced from lignocellulosic biomass and a detailed understanding of their combustion properties is essential to identifying their performance in existing and advanced engines. Leaving the oxygen found in plant biopolymers in the resulting biofuels can lead to significant cost reduction that is required to remove these oxygen atoms and in some cases the oxygen functional groups provide superior combustion performance. While oxygenated biofuels may be advantageous, <i>a priori</i> identification of suitable oxygenates can be quite difficult due to the research time required to prepare new biofuels and the amount of material that is often required for testing. With the increasing high throughput and accuracy of computational molecular modeling, this approach can be used to facilitate and accelerate the development of oxygenated biofuels by predicting combustion properties without having to prepare the fuel.<br/>We have been using molecular modeling and kinetic analysis to understand how different oxygenated functional groups affect autoignition, which is a key fuel combustion characteristic that determines the ignition delay and directly impacts research octane number (RON) for spark ignition engines and cetane number (CN) for compression ignition engines. G4 calculations are used to predict reaction barriers and reaction energies, while B3LYP is used to estimate vibrational frequencies and hindered rotor potentials for the critical reactions in the autoignition of common oxygenated biofuels. The low temperature oxidation of a homologous series of oxygenate compounds, including aldehydes, ketones, esters and ethers were investigated and the results will be discussed and compared to experimental measurements of ignition delay.<br/>

Quantum molecular modeling of autoignition of biofuels

256th National Meeting (2018)

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