skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Thermal decomposition of CH{sub 3}CHO studied by matrix infrared spectroscopy and photoionization mass spectroscopy

Abstract

A heated SiC microtubular reactor has been used to decompose acetaldehyde and its isotopomers (CH{sub 3}CDO, CD{sub 3}CHO, and CD{sub 3}CDO). The pyrolysis experiments are carried out by passing a dilute mixture of acetaldehyde (roughly 0.1%-1%) entrained in a stream of a buffer gas (either He or Ar) through a heated SiC reactor that is 2-3 cm long and 1 mm in diameter. Typical pressures in the reactor are 50-200 Torr with the SiC tube wall temperature in the range 1200-1900 K. Characteristic residence times in the reactor are 50-200 {mu}s after which the gas mixture emerges as a skimmed molecular beam at a pressure of approximately 10 {mu}Torr. The reactor has been modified so that both pulsed and continuous modes can be studied, and results from both flow regimes are presented. Using various detection methods (Fourier transform infrared spectroscopy and both fixed wavelength and tunable synchrotron radiation photoionization mass spectrometry), a number of products formed at early pyrolysis times (roughly 100-200 {mu}s) are identified: H, H{sub 2}, CH{sub 3}, CO, CH{sub 2}=CHOH, HC{identical_to}CH, H{sub 2}O, and CH{sub 2}=C=O; trace quantities of other species are also observed in some of the experiments. Pyrolysis of rare isotopomers of acetaldehyde produces characteristicmore » isotopic signatures in the reaction products, which offers insight into reaction mechanisms that occur in the reactor. In particular, while the principal unimolecular processes appear to be radical decomposition CH{sub 3}CHO (+M) {yields} CH{sub 3}+ H + CO and isomerization of acetaldehyde to vinyl alcohol, it appears that the CH{sub 2}CO and HCCH are formed (perhaps exclusively) by bimolecular reactions, especially those involving hydrogen atom attacks.« less

Authors:
 [1];  [2]; ; ;  [1];  [3];  [4]; ; ;  [5];  [6];  [7]; ;  [8];  [9]
  1. Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States)
  2. (United States)
  3. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099 (United States)
  4. National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States)
  5. Chemical Sciences Division, LBNL MS 6R-2100, Berkeley, California 94720 (United States)
  6. Combustion Research Facility, Sandia National Laboratories, P.O. Box 969 MS 9055, Livermore, California 94551-0969 (United States)
  7. Integrated Instrument Design Facility, CIRES, University of Colorado, Boulder, Colorado 80309-0216 (United States)
  8. Center for Combustion and Environmental Research, Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0427 (United States)
  9. Institute for Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
22099066
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 137; Journal Issue: 16; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; ACETALDEHYDE; CARBON MONOXIDE; FOURIER TRANSFORM SPECTROMETERS; FOURIER TRANSFORMATION; INFRARED SPECTRA; ISOMERIZATION; MASS SPECTROSCOPY; MOLECULAR BEAMS; PHOTOIONIZATION; PYROLYSIS; REACTION KINETICS; SILICON CARBIDES; SYNCHROTRON RADIATION

Citation Formats

Vasiliou, AnGayle K., National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401, Piech, Krzysztof M., Reed, Beth, Ellison, G. Barney, Zhang Xu, Nimlos, Mark R., Ahmed, Musahid, Golan, Amir, Kostko, Oleg, Osborn, David L., David, Donald E., Urness, Kimberly N., Daily, John W., and Stanton, John F. Thermal decomposition of CH{sub 3}CHO studied by matrix infrared spectroscopy and photoionization mass spectroscopy. United States: N. p., 2012. Web. doi:10.1063/1.4759050.
Vasiliou, AnGayle K., National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401, Piech, Krzysztof M., Reed, Beth, Ellison, G. Barney, Zhang Xu, Nimlos, Mark R., Ahmed, Musahid, Golan, Amir, Kostko, Oleg, Osborn, David L., David, Donald E., Urness, Kimberly N., Daily, John W., & Stanton, John F. Thermal decomposition of CH{sub 3}CHO studied by matrix infrared spectroscopy and photoionization mass spectroscopy. United States. doi:10.1063/1.4759050.
Vasiliou, AnGayle K., National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401, Piech, Krzysztof M., Reed, Beth, Ellison, G. Barney, Zhang Xu, Nimlos, Mark R., Ahmed, Musahid, Golan, Amir, Kostko, Oleg, Osborn, David L., David, Donald E., Urness, Kimberly N., Daily, John W., and Stanton, John F. Sun . "Thermal decomposition of CH{sub 3}CHO studied by matrix infrared spectroscopy and photoionization mass spectroscopy". United States. doi:10.1063/1.4759050.
@article{osti_22099066,
title = {Thermal decomposition of CH{sub 3}CHO studied by matrix infrared spectroscopy and photoionization mass spectroscopy},
author = {Vasiliou, AnGayle K. and National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 and Piech, Krzysztof M. and Reed, Beth and Ellison, G. Barney and Zhang Xu and Nimlos, Mark R. and Ahmed, Musahid and Golan, Amir and Kostko, Oleg and Osborn, David L. and David, Donald E. and Urness, Kimberly N. and Daily, John W. and Stanton, John F.},
abstractNote = {A heated SiC microtubular reactor has been used to decompose acetaldehyde and its isotopomers (CH{sub 3}CDO, CD{sub 3}CHO, and CD{sub 3}CDO). The pyrolysis experiments are carried out by passing a dilute mixture of acetaldehyde (roughly 0.1%-1%) entrained in a stream of a buffer gas (either He or Ar) through a heated SiC reactor that is 2-3 cm long and 1 mm in diameter. Typical pressures in the reactor are 50-200 Torr with the SiC tube wall temperature in the range 1200-1900 K. Characteristic residence times in the reactor are 50-200 {mu}s after which the gas mixture emerges as a skimmed molecular beam at a pressure of approximately 10 {mu}Torr. The reactor has been modified so that both pulsed and continuous modes can be studied, and results from both flow regimes are presented. Using various detection methods (Fourier transform infrared spectroscopy and both fixed wavelength and tunable synchrotron radiation photoionization mass spectrometry), a number of products formed at early pyrolysis times (roughly 100-200 {mu}s) are identified: H, H{sub 2}, CH{sub 3}, CO, CH{sub 2}=CHOH, HC{identical_to}CH, H{sub 2}O, and CH{sub 2}=C=O; trace quantities of other species are also observed in some of the experiments. Pyrolysis of rare isotopomers of acetaldehyde produces characteristic isotopic signatures in the reaction products, which offers insight into reaction mechanisms that occur in the reactor. In particular, while the principal unimolecular processes appear to be radical decomposition CH{sub 3}CHO (+M) {yields} CH{sub 3}+ H + CO and isomerization of acetaldehyde to vinyl alcohol, it appears that the CH{sub 2}CO and HCCH are formed (perhaps exclusively) by bimolecular reactions, especially those involving hydrogen atom attacks.},
doi = {10.1063/1.4759050},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 16,
volume = 137,
place = {United States},
year = {2012},
month = {10}
}