Abstract
The gas-phase chemistry of the hypergolic system CH3NHNH2 - monomethylhydrazine (MMH), with oxidizers NO2/N2O4 at room temperature and 1atm N2 was investigated experimentally using a gold-coated chamber reactor, coupled with a Fourier transform infrared (FTIR) spectrometer. The IR-active species identified in the early reactions include HONO, monomethylhydrazinium nitrite (MMH·HONO), methyl diazene (CH3NNH), methyl nitrate (CH3ONO2), methyl nitrite (CH3ONO), nitromethane (CH3NO2), methyl azide (CH3N3), H2O, N2O and NO. In order to elucidate the mechanisms by which these observed products are formed, we carried out quantum mechanics calculations [CCSD(T)/M06-2X] for the possible reaction pathways. Based on these studies, we propose that the oxidation of MMH in an atmosphere of NO2 occurs via two mechanisms: (1) sequential H-abstraction and HONO formation, and (2) reaction of MMH with asymmetric ONONO2, leading to formation of methyl nitrate. These mechanisms successfully explain all intermediates observed experimentally. We conclude that the formation of asymmetric ONONO2 is assisted by an aerosol formed by HONO and MMH that provides a large surface area for ONONO2 to condense, leading to the generation of methyl nitrate. Thus we propose that the overall pre-ignition process involves both gas-phase and aerosol-phase reactions.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 970-981 |
| Number of pages | 12 |
| Journal | Combustion and Flame |
| Volume | 160 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1 2013 |
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All Science Journal Classification (ASJC) codes
- Chemistry(all)
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy(all)
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Experimental and quantum mechanics investigations of early reactions of monomethylhydrazine with mixtures of NO2 and N2O4. / Liu, Wei Guang; Wang, Shiqing; Dasgupta, Siddharth; Thynell, Stefan; Goddard, William A.; Zybin, Sergey; Yetter, Richard A.
In: Combustion and Flame, Vol. 160, No. 5, 01.05.2013, p. 970-981.Research output: Contribution to journal › Article
TY - JOUR
T1 - Experimental and quantum mechanics investigations of early reactions of monomethylhydrazine with mixtures of NO2 and N2O4
AU - Liu, Wei Guang
AU - Wang, Shiqing
AU - Dasgupta, Siddharth
AU - Thynell, Stefan
AU - Goddard, William A.
AU - Zybin, Sergey
AU - Yetter, Richard A.
PY - 2013/5/1
Y1 - 2013/5/1
N2 - The gas-phase chemistry of the hypergolic system CH3NHNH2 - monomethylhydrazine (MMH), with oxidizers NO2/N2O4 at room temperature and 1atm N2 was investigated experimentally using a gold-coated chamber reactor, coupled with a Fourier transform infrared (FTIR) spectrometer. The IR-active species identified in the early reactions include HONO, monomethylhydrazinium nitrite (MMH·HONO), methyl diazene (CH3NNH), methyl nitrate (CH3ONO2), methyl nitrite (CH3ONO), nitromethane (CH3NO2), methyl azide (CH3N3), H2O, N2O and NO. In order to elucidate the mechanisms by which these observed products are formed, we carried out quantum mechanics calculations [CCSD(T)/M06-2X] for the possible reaction pathways. Based on these studies, we propose that the oxidation of MMH in an atmosphere of NO2 occurs via two mechanisms: (1) sequential H-abstraction and HONO formation, and (2) reaction of MMH with asymmetric ONONO2, leading to formation of methyl nitrate. These mechanisms successfully explain all intermediates observed experimentally. We conclude that the formation of asymmetric ONONO2 is assisted by an aerosol formed by HONO and MMH that provides a large surface area for ONONO2 to condense, leading to the generation of methyl nitrate. Thus we propose that the overall pre-ignition process involves both gas-phase and aerosol-phase reactions.
AB - The gas-phase chemistry of the hypergolic system CH3NHNH2 - monomethylhydrazine (MMH), with oxidizers NO2/N2O4 at room temperature and 1atm N2 was investigated experimentally using a gold-coated chamber reactor, coupled with a Fourier transform infrared (FTIR) spectrometer. The IR-active species identified in the early reactions include HONO, monomethylhydrazinium nitrite (MMH·HONO), methyl diazene (CH3NNH), methyl nitrate (CH3ONO2), methyl nitrite (CH3ONO), nitromethane (CH3NO2), methyl azide (CH3N3), H2O, N2O and NO. In order to elucidate the mechanisms by which these observed products are formed, we carried out quantum mechanics calculations [CCSD(T)/M06-2X] for the possible reaction pathways. Based on these studies, we propose that the oxidation of MMH in an atmosphere of NO2 occurs via two mechanisms: (1) sequential H-abstraction and HONO formation, and (2) reaction of MMH with asymmetric ONONO2, leading to formation of methyl nitrate. These mechanisms successfully explain all intermediates observed experimentally. We conclude that the formation of asymmetric ONONO2 is assisted by an aerosol formed by HONO and MMH that provides a large surface area for ONONO2 to condense, leading to the generation of methyl nitrate. Thus we propose that the overall pre-ignition process involves both gas-phase and aerosol-phase reactions.
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U2 - 10.1016/j.combustflame.2013.01.012
DO - 10.1016/j.combustflame.2013.01.012
M3 - Article
AN - SCOPUS:84875099375
VL - 160
SP - 970
EP - 981
JO - Combustion and Flame
JF - Combustion and Flame
SN - 0010-2180
IS - 5
ER -