Quantification of the Keto-Hydroperoxide (HOOCH2OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

This work provides new temperature-dependent mole fractions of elusive intermediates relevant to the low-temperature oxidation of dimethyl ether (DME). It extends the previous study of Moshammer et al. [ J. Phys. Chem. A 2015, 119, 7361–7374] in which a combination of a jet-stirred reactor and molecular beam mass spectrometry with single-photon ionization via tunable synchrotron-generated vacuum-ultraviolet radiation was used to identify (but not quantify) several highly oxygenated species. Here, temperature-dependent concentration profiles of 17 components were determined in the range of 450–1000 K and compared to up-to-date kinetic modeling results. Special emphasis is paid toward the validation and application of a theoretical method for predicting photoionization cross sections that are hard to obtain experimentally but essential to turn mass spectral data into mole fraction profiles. The presented approach enabled the quantification of the hydroperoxymethyl formate (HOOCH2OCH2O), which is a key intermediate in the low-temperature oxidation of DME. The quantification of this keto-hydroperoxide together with the temperature-dependent concentration profiles of other intermediates including H2O2, HCOOH, CH3OCHO, and CH3OOH reveals new opportunities for the development of a next-generation DME combustion chemistry mechanism.

Citation

Moshammer K, Jasper AW, Popolan-Vaida DM, Wang Z, Bhavani Shankar VS, et al. (2016) Quantification of the Keto-Hydroperoxide (HOOCH2OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether. The Journal of Physical Chemistry A 120: 7890–7901. Available: http://dx.doi.org/10.1021/acs.jpca.6b06634.

Sponsors

This material is based upon work supported by the U.S.Department of Energy (DOE), Office of Science, Office ofBasic Energy Sciences. D.M.P.-V. is supported by the DOE Gas Phase Chemical Physics Program at Lawrence Berkeley National Laboratory, under Contract DEAC02-05CH11231. We thank Paul Fugazzi for technical assistance and Profs.Leone, Sarathy, and Kohse-Hoinghaus for continuing support of this project, and Prof. Lucchese for providing his code. P.D. received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement 291049-2G-CSafe. Z.W. and V.S.B.S. acknowledge competitive research funding given to the Clean Combustion Research Center from the King Abdullah University of Science and Technology. The Advance Light Source is supported by the Director, Office of Science,Office of Basic Energy Sciences, of the U.S. DOE under Contract DEAC02-05CH11231. Sandia is a multimission laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the National Nuclear Security Administration under Contract DE-AC04-94-AL85000.