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Titel |
Differences in the reactivity of ammonium salts with methylamine |
VerfasserIn |
Y. Liu, C. Han, C. Liu, J. Ma, Q. Ma, H. He |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 11 ; Nr. 12, no. 11 (2012-06-01), S.4855-4865 |
Datensatznummer |
250011215
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Publikation (Nr.) |
copernicus.org/acp-12-4855-2012.pdf |
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Zusammenfassung |
The heterogeneous uptake of methylamine (MA) onto (NH4)2SO4,
NH4HSO4, NH4NO3 and NH4Cl was investigated using a
Knudsen cell reactor coupled to a quadrupole mass spectrometer, in situ Raman
spectrometer and theoretical calculations. Exchange reactions were observed
between MA and NH4NO3, (NH4)2SO4, and NH4Cl
were observed at 298 K. Simple acid-base reaction for MA was found taking
place on NH4HSO4. CH3NH3NO3 and CH3NH3Cl
are not stable at low pressure and have higher dissociation vapor pressure
than methylammonium sulfate. The observed uptake coefficients of MA on
(NH4)2SO4, NH4HSO4, NH4NO3 and NH4Cl
at 298 K were measured to be 6.30±1.03×10−3,
1.78±0.36×10−2, 8.79±1.99×10−3 and
2.29±0.28×10−3, respectively. A linear free energy
relationship was found for the heterogeneous reactions between MA and
NH4Cl, (NH4)2SO4 and NH4NO3. Namely, the
natural logarithm of uptake coefficients of MA on these ammonium salts is
linearly related to the electrostatic potential of the H atom in the
NH4+ group. |
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