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| Titel |
Particle Formation in Photo-oxidation Experiments with 2-Aminoethanol (MEA) |
| VerfasserIn |
Matthias Karl, Barbara D'Anna, Christian George, Stephanie King, Armin Wisthaler, Christian Dye, Claus Jørgen Nielsen |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038798
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| Zusammenfassung |
| 2-Aminoethanol (MEA, NH2CH2CH2OH) is a widely used compound for post combustion
CO2 capture in modern Carbon Capture Systems (CCS). The capture process entails
emissions of substantial amounts of amines to the atmosphere. Quantitative knowledge
about the atmospheric fate of MEA, including partitioning to particles and droplets
and contribution to formation of new particles, is prerequisite to an Environmental
Impact Assessment of amine-based CO2-capture. Despite the need for reliable data
only few studies on the atmospheric photo-oxidation of MEA exist to date. The
atmospheric photo-oxidation of MEA was studied at the European Photochemical
Reactor, EUPHORE, in Valencia (Spain). The photochemical degradation of MEA was
monitored in situ by FT-IR and on-line by PTR-TOF-MS, and the formation of
particles by SMPS and AMS on-line instruments and filter sampling followed by
analysis with LC/HRMS(TOF). The experiments were carried out under varying NOx
conditions and initial MEA gas phase mixing ratios ranged between 100 and 700
ppbv. The photo-oxidation of MEA was found to give raise to ozone and significant
formation of particles. Aerosols were formed immediately after the exposure of the
chamber to sunlight with number concentrations ranging up to 104 particles/cm3.
Monitored particle number size distributions revealed steep growth curves during the
experiments and total aerosol mass concentrations increased up to 230 μg/m3. The aerosol
mass spectrum is found to be quite different from that of the pure (stoichiometric)
ethanolammonium nitrate salt and contains a small fraction of higher molecular weight
organics, consisting of C3 and C4 fragments. The high molecular weight organic fraction
increased throughout the course of the experiment, but contributed only 1.1% of
the total aerosol mass. This is in line with the work of Murphy et al. (2007) who
indicate that the mass yield of non-salt aerosol during photo-oxidation experiments
with aliphatic amines is in general low. The recently developed sectional aerosol
dynamic model MAFOR was applied to investigate the mass closure for MEA during
photo-oxidation experiments. MAFOR has been extended in the frame of this study to
include 1) chamber specific losses of gases and particles, 2) chamber specific sources, 3)
monitored time series, 4) MEA photo-oxidation chemistry, 5) condensation of a
low-volatile MEA oxidation product to existing particles, 6) condensation of a gas
phase acid-base equilibrium reaction product, and 7) nucleation involving MEA and
nitric acid. According to model simulations, MEA is to a large extent degraded
by chemical reaction with the OH radical (30-50%), a substantial amount of the
injected MEA amount (40-60%) is converted into particle mass (gas-to-particle
conversion) during the photo-oxidation experiments, while about 10-30% of the
initial MEA amount is lost to the walls or by dilution through replenishment flow. |
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