Sooting Tendencies of Aromatic Hydrocarbons with Oxygen-Containing Side-Chains [article]

Brian P. Beekley, Charles McEnally, Peter C. St. John, Seonah Kim, Abhishek Jain, Hyunguk Kwon, Yuan Xuan, Lisa D. Pfefferle
2018 Figshare  
Paper presented at the 2018 Spring Technical Meeting of the Eastern States Section of the Combustion Institute, March 4-7 2018, State College PA. Yield Sooting Index (YSI) was determined for 13 oxygen-containing aromatic compounds by measuring line-of-sight spectral radiance (LSSR) in a laminar non-premixed methane/air flame doped with 1000 ppm of each compound. The compounds included anisole (methoxybenzene), other aromatic ethers, and phenols. The presence of oxygen greatly reduced soot
more » ... ion in some cases, but increased it in others. Thus oxygenated aromatics are potentially valuable as fuel components with intrinsically low particulate emissions, but the specific structure is important. Compounds containing an aromatic ring with an adjacent oxygen atom tended to have a lower sooting tendency than did compounds with oxygen atoms elsewhere in the side chain. This observation was quantitatively explored using Density Functional Theory (DFT) calculations. The bond dissociation energies for nine aromatic hydrocarbons and oxygenates were calculated using GGA B3LYP density functions with 6-31G(d) basis sets. When possible, unimolecular dissociation to phenoxy radical was favored and resulted in much lower YSIs than similar compounds where the oxygen atom was not adjacent to the aromatic ring. Structures that dissociated to benzyl radical had much higher sooting tendencies, sometimes by over a factor of two in comparison to phenoxy-forming compounds.
doi:10.6084/m9.figshare.5993527 fatcat:ivmjcrpukzfkfnesjxgyb7a5hy