secondary organic aerosol formation from gas and particle phase reactions of aromatic hydrocarbons...
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Secondary Organic Aerosol Secondary Organic Aerosol Formation from Gas and Formation from Gas and
Particle Phase Reactions of Particle Phase Reactions of Aromatic HydrocarbonsAromatic Hydrocarbons
Di HuDi HuPhD Committee MeetingPhD Committee Meeting
March 24, 2004March 24, 2004
Outline Outline
Why aromaticsWhy aromatics
SOA formation potential from SOA formation potential from aromaticsaromatics
Overall goal of my researchOverall goal of my research
Sources of AromaticsSources of Aromatics
Anthropogenic SourcesAnthropogenic SourcesTransportationTransportationSolvent useSolvent useFuel combustionFuel combustion
In the US, transportation sources In the US, transportation sources contribute contribute ~67%~67% to the total aromatic to the total aromatic emissions which range from emissions which range from 1.9 x 101.9 x 1066 to to 2.4 x 102.4 x 1066 tons/year. tons/year.
Why aromatics?Why aromatics?Total US VOC Reactivity Budget
Natural Alkanes40%
Natural Isoprene23%
Other Natural Compounds
6%
Anthropogenic Alkanes12%
Anthropogenic Aromatics
10%
Other Anthropogenic Compounds
9%
Why aromatics?Why aromatics?
TolueneToluene 23.5%23.5%
m,p-Xylenem,p-Xylene 12.6%12.6%
1,2,4-Trimetylbenzene1,2,4-Trimetylbenzene8.5%8.5%
BenzeneBenzene 7.4%7.4%
Composition, Chemistry, and Climate of the Atmosphere; New Composition, Chemistry, and Climate of the Atmosphere; New York, 1995York, 1995
Average Composition in 1ppmC Urban Air
Alkenes12%
Alkanes53%
Unspeciated
6%
Aldehydes2%
Aromatics27%
Jenkin et al. show that in their Jenkin et al. show that in their model calculations up to model calculations up to 40%40% of of photochemically produced photochemically produced ozoneozone can be attributed to emissions of can be attributed to emissions of aromatics in urban areas. aromatics in urban areas. (Atmos. Environ. 1996)(Atmos. Environ. 1996)
SOA Formation Potential of SOA Formation Potential of AromaticsAromatics
CH3
O
O
OH
CH3
O
OH
O
CHO CHO
OH
CHO
OH
O2N
CH3
O
O
OH
O
CH3
O
O
O
CH3
O
O
O
H
OO
H3C
H
O O
CH3
O
H
O
O
H
CH3
O
O
H
H
O
O
H
H
O
O
O
H
CH3
O
O
H
H
O
O
O
CH3
CH3
O
H
O
H
O
O
HO
O
H3C
OH
OHO
CH3
O
O
HO
H
O
O
OH
H
O
O
OCH3
O
OH
OOH
CH3
O
O
O
CH3
O
OH
OO
OH
OO
OH
CH3OH O
O
H
O
OH
CH3
O
OHO
H
O
H
OHO
CH3
O
H
OH
CH3 H
O
OH
O
H H
O
OH
O
H
CH3
O
O
H
OOH CH3
O
H
O
OH
OOO
OH
CH3H O
O
Aromatic aldehydes
Ring-retaining carbonyls
Ring-opening carbonyls
Ring-opening oxo-carboxylic acids
Ring-opeining hydoxy-carbonyls
SOA Formation Potential of SOA Formation Potential of AromaticsAromatics
Recent research has provided strong Recent research has provided strong evidence for polymerization evidence for polymerization reactionsreactions on aromatic aerosols. on aromatic aerosols.
This results in a much lower volatility This results in a much lower volatility SOA material and SOA material and higher aerosol higher aerosol yieldsyields than partitioning can predict. than partitioning can predict.
Evidences for Polymer Evidences for Polymer Formation in SOA from the Formation in SOA from the
Photo-oxidation of Photo-oxidation of Aromatics/NOx SystemAromatics/NOx System
FTIR Spectra of Toluene and FTIR Spectra of Toluene and Glyoxal AerosolsGlyoxal Aerosols
Slide from Dr. Myoseon Jang Slide from Dr. Myoseon Jang
-0.004
0.000
0.004
0.008
0.012
0.016
0.020
0.024
0.028
0.032
0.036
0.040
8001200160020002400280032003600
wavelength (cm-1)
ab
so
rban
ce (
gly
oxal)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
ab
so
rban
ce (
tolu
en
e)
Glyoxal/Acid-Catalyst
OH & COOH
15
59
, N
O217
25
, C
=O
16
45
, O
NO
2
13
40
, N
O2
12
82
, O
NO
2 s
t
C-O
-C s
tretc
h
Toluene/NOx
(NH
4)2
SO
4, 1
10
0
Toluene/NOx/Acid-Catalyst
Kalberer et al. recently have identified Kalberer et al. recently have identified polymers as the main constituents of polymers as the main constituents of SOA formed from the photo-oxidation SOA formed from the photo-oxidation of 1,3,5-trimethylbezene, which of 1,3,5-trimethylbezene, which account for about account for about 50%50% of the aerosol of the aerosol mass after 30 hours of aging. mass after 30 hours of aging. ((Science, 2004Science, 2004))
LDI-TOFMS Spectrum of SOA from LDI-TOFMS Spectrum of SOA from Photo-oxidation of 1,3,5-Photo-oxidation of 1,3,5-
TrimethylbezeneTrimethylbezene
Time Evolution of Polymer in Time Evolution of Polymer in SOA Measured by LDI-MSSOA Measured by LDI-MS
Overall Goal of This ProjectOverall Goal of This Project
Integrate particle phase Integrate particle phase heterogeneous processes with gas heterogeneous processes with gas phase reaction as a unified, multi-phase reaction as a unified, multi-phase, chemical reaction phase, chemical reaction mechanism, which will ultimately mechanism, which will ultimately permit the prediction of amounts of permit the prediction of amounts of SOA that result from aromatics SOA that result from aromatics reacting in the atmosphere.reacting in the atmosphere.
Overall ApproachOverall Approach
Kinetic mechanism developmentKinetic mechanism development
Outdoor chamber experimentsOutdoor chamber experiments
Simulation of chamber experimentsSimulation of chamber experiments
Gas Phase ReactionsGas Phase Reactions
Toluene react with OHToluene react with OH
OCH3
OHO
.
Recent research from Mario Molina’s Recent research from Mario Molina’s group has shown that the pathway to group has shown that the pathway to form epoxide radicals are neglectable.form epoxide radicals are neglectable.
Existing MechanismsExisting Mechanisms
Carbon BondCarbon Bond
Carter’s MechanismCarter’s Mechanism
Master Chemical MechanismMaster Chemical Mechanism
Toluene react with OHToluene react with OH
'C7H8' + OH ---->'C7H8' + OH ----> 0.720.72*'CH3-C6H5(OH)-OO.' +*'CH3-C6H5(OH)-OO.' +
0.10.1*'C6H5CO-H' +*'C6H5CO-H' + 0.180.18*'CRESOL’*'CRESOL’
++0.280.28*HO2*HO2 ++ 0.10.1*XO2 *XO2
@ @ 1.18E-121.18E-12* EXP(* EXP(338.0338.0/TK)/TK)
'CH3-C6H5(OH)-OO.' + NO ---->'CH3-C6H5(OH)-OO.' + NO ----> 0.550.55*'H-CO-CH=CH-CO-H‘*'H-CO-CH=CH-CO-H‘
++ 0.110.11*'CH3-CO-CH=CH-CO-H'*'CH3-CO-CH=CH-CO-H' ++ 0.340.34*'H-CO-C(CH3)=CH-CO-*'H-CO-C(CH3)=CH-CO-
H'H' ++ 0.550.55*'CH3-CO-CO-H' +*'CH3-CO-CO-H' +
0.450.45*'H-CO-CO-H'+ NO2 +HO*'H-CO-CO-H'+ NO2 +HO
@@ 8.1E-128.1E-12
Reaction of 1Reaction of 1stst Generation Generation ProductProduct
'CH3-CO-CH=CH-CO-H' + OH ----> 'CH3-CO-CH=CH-CO-H' + OH ----> 0.20.2*('CH3-CO-CH=CH-CO-O2.‘*('CH3-CO-CH=CH-CO-O2.‘ +H2O) + +H2O) + 0.40.4*'OXOCYL_RAD' + *'OXOCYL_RAD' + 0.20.2*'CH3-CO-CH(OH)-CH(OO.)-CO-H'*'CH3-CO-CH(OH)-CH(OO.)-CO-H' + + 0.20.2*'CH3-CO-CH(OO.)-CH(OH)-CO-H'*'CH3-CO-CH(OO.)-CH(OH)-CO-H' @ @ 5.58E-115.58E-11
'OXOCYL_RAD' + NO -O2-> 'Maleic anhydrid' + 'CH3.' + NO2 'OXOCYL_RAD' + NO -O2-> 'Maleic anhydrid' + 'CH3.' + NO2 @ @ 3.03.0*k_MEO2_NO*k_MEO2_NO
'CH3-CO-CH(OH)-CH(OO.)-CO-H' + NO ---->'CH3-CO-CH(OH)-CH(OO.)-CO-H' + NO ---->0.130.13*C5OHNO3 *C5OHNO3 + + 0.870.87*('CH3-CO-CH(OH)*('CH3-CO-CH(OH)--CH(O.)-CO-H' + CH(O.)-CO-H' +
NO2)NO2) @ @ 0.710.71*k_MEO2_NO*k_MEO2_NO
'CH3-CO-CH(OH)-CH(O.)-CO-H' + O2 ----> 'CH3-CO-CH(OH)-CH(O.)-CO-H' + O2 ----> 0.30.3*(C4OHALD + CO + H2O) *(C4OHALD + CO + H2O) + + 0.50.5*('CH3-CO-CO-H'+ 'H-CO-CO-H'+ HO2)*('CH3-CO-CO-H'+ 'H-CO-CO-H'+ HO2) + + 0.20.2*(C5OHALD+ HO2)*(C5OHALD+ HO2) @ k_DEC@ k_DEC
22ndnd Generation Gas Phase Generation Gas Phase ProductsProducts
33rdrd Generation Gas Phase Generation Gas Phase ProductsProducts
Simulation Results of Gas Simulation Results of Gas Phase ChemistryPhase Chemistry
Particle Formation Particle Formation ProcessesProcesses
G/P PartitioningG/P Partitioning
Particle Phase ReactionsParticle Phase Reactions
G/P PartitioningG/P Partitioning
CH3
O
OH
O
KKpp = =kkonon//kkoffoff = 7.501RTf = 7.501RTfomom/(10/(1099MwMwpp00LL))
kkoffoff=k=kbbT/T/hh exp(-E exp(-Eaa/RT)/RT)
kkbbT/T/h h = 6.21= 6.2110101212 sec sec-1 -1 at 298Kat 298K
Relate ERelate Eaa to log to log ppooLL
kkonon==KKPPkkoffoff
CH3
O
OH
O
To Represent These To Represent These Processes in the MechanismProcesses in the Mechanism
C4OHALDC4OHALDgasgas + SEED ----> C4OHALD + SEED ----> C4OHALDpartpart + SEED+ SEED @ kon@ kon
C4OHALDC4OHALDgasgas + TSP ----> C4OHALD + TSP ----> C4OHALDpartpart + TSP + TSP @ kon@ kon
C4OHALDC4OHALDpartpart ----> C4OHALD ----> C4OHALDgasgas @ koff @ koff
Particle Phase ReactionsParticle Phase Reactions
Particle Phase ReactionsParticle Phase Reactions
Particle Phase ReactionsParticle Phase Reactions
HH
O
O
CH3
O
OH
O
HH
O
O CH3
O
OH
O
GlyP + H2O ----> Gly2OHP @ kpart1 GlyP + H2O ----> Gly2OHP @ kpart1
Gly2OHP + H2O ----> Gly4OHPGly2OHP + H2O ----> Gly4OHP @ kpart2 @ kpart2
Gly4OHP + GlyAcidP ----> pre-Poly1 @ kpart3Gly4OHP + GlyAcidP ----> pre-Poly1 @ kpart3
Pre-Poly1 + C4OHALD ----> Poly1Pre-Poly1 + C4OHALD ----> Poly1 @ @ kpart4kpart4
Do these reactions well represent what Do these reactions well represent what really happens in the particle phase?really happens in the particle phase?
Particle phase reaction rate coefficientsParticle phase reaction rate coefficients
Outdoor Chamber Outdoor Chamber ExperimentsExperiments
The Outdoor Chamber Reactor The Outdoor Chamber Reactor SystemSystem
Hanging TeflonHanging Teflon
Dual 270mDual 270m33 chamber chamber fine particle t fine particle t 1/21/2 >17 h >17 h
Product AnalysisProduct Analysis
Toluene/propylene/NOx/sunlight Toluene/propylene/NOx/sunlight chamber experiments were carried chamber experiments were carried out with neutral seed and acidic out with neutral seed and acidic seed. seed.
Analytical MethodsAnalytical Methods
DerivatizationDerivatization methods to identify methods to identify the the precursors of polymersprecursors of polymers..
LC-ESIMS/MSLC-ESIMS/MS to identify to identify structure of structure of polymers. polymers.
PFBHA PFBHA O-(2,3,4,5,6-O-(2,3,4,5,6-pentafluorobenzyl) -hydroxylamine for pentafluorobenzyl) -hydroxylamine for
carbonyl groupscarbonyl groups
FF
F
F F
CH2 O NH2
H2O
PFBHA
R1
C
O
R2
CH2
F F
F
FF
ONC
R1
R2
acetone or ketone
PFBBrPFBBr, Pentafluorobenzyl bromide , Pentafluorobenzyl bromide derivatization for carboxylic and aromatic-OHderivatization for carboxylic and aromatic-OH
CH2 C
O
OH
H3C CH3
C
O
H O
FF
F
F F
CH2Br
C CH2
O
HO C O CH2
F F
F
FF
OH3C CH3
HBr
PFBBr
C CH2
O
O C O CH2
F F
F
FF
OCH3 CH3
CH2
FF
F
F F
2 HBr
The three slides are from Prof. Rich KamensThe three slides are from Prof. Rich Kamens
BSTFA BSTFA for hydroxyl, and/or carboxylic for hydroxyl, and/or carboxylic groupsgroups
BSTFA
R OH
carboxylic acid or alcohol
C N
Si(CH3)3
CF3
O(CH3)3Si
R
O(CH3)3Si
BFBF33-CH-CH33OH + BSTFA OH + BSTFA Derivatization MethodDerivatization Method
C
O
HO CH2 C
OH
C
CH3
O
OH + CH3 OHBF3
excess
C
O
CH3O CH2 C
OH
C
CH3
O
OCH3
C
O
CH3O CH2 C
O
C
CH3
O
OCH3
Si(CH3)3
C NSi(CH3)3F3C
O
Si(CH3)3
C
O
CH3O CH2 C
OH
C
CH3
O
OCH3 +
excess
+
C NHSi(CH3)3F3C
O
C NH2F3C
O
TMCS
GC-ITMS analysisGC-ITMS analysis
- electron impact ionization (EI)- electron impact ionization (EI)
- methane chemical ionization (CI-methane)- methane chemical ionization (CI-methane)
- tandem mass spectrometry (MS/MS)- tandem mass spectrometry (MS/MS)Slide from Dr. Mohammed JaouiSlide from Dr. Mohammed Jaoui
Citramalic acid
Particle Phase Reaction Rate Particle Phase Reaction Rate CoefficientsCoefficients
Too ambitious to measure the rate Too ambitious to measure the rate coefficient of each single particle phase coefficient of each single particle phase reaction.reaction.
Cross reaction of the multi-functional Cross reaction of the multi-functional aldehydesaldehydes
Many products are not commercially Many products are not commercially available.available.
Simple methyglyoxal experiments (daytime/NOx, Simple methyglyoxal experiments (daytime/NOx, nighttime)nighttime)
Do chamber experiment with different toluene and Do chamber experiment with different toluene and NOx concentrations at different RH and NOx concentrations at different RH and temperature.temperature.
Measure particle mass, acidity and HNO3 in particle Measure particle mass, acidity and HNO3 in particle phase.phase.
Explore relationships that influence rates of Explore relationships that influence rates of particle formationparticle formation– particle HNO3particle HNO3– RH and temperatureRH and temperature
Overall ApproachOverall Approach
Kinetic mechanism developmentKinetic mechanism development
Outdoor chamber experimentsOutdoor chamber experiments
Simulation of chamber experimentsSimulation of chamber experiments
Future PlanFuture Plan
Methylglyoxal experiments in this summerMethylglyoxal experiments in this summer
Some of the toluene/NOSome of the toluene/NOx x chamber chamber
experimentsexperiments
Proposal at the end of this summerProposal at the end of this summer
Thank you for your Thank you for your timetime