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University of Leeds Department of Chemistry. Gas phase MCM development. Andrew Rickard, Claire Bloss, Mike Jenkin, Sam Saunders and Mike Pilling. Overview. Update to MCMv3.1 Aromatic chemistry New schemes (MBO) Development of new schemes (MOST) Ethylene glycol di-vinyl ether (DVE-1) - PowerPoint PPT Presentation
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Andrew Rickard, Claire Bloss, Mike Jenkin, Sam Saunders and Mike Pilling
Gas phase MCM development
University of LeedsDepartment of Chemistry
Overview
Update to MCMv3.1
• Aromatic chemistry• New schemes (MBO)
Development of new schemes (MOST)
• Ethylene glycol di-vinyl ether (DVE-1)• Ethylene glycol mono-vinyl ether (MVE-1)• MOST EUPHORE 2005 photo-smog experiments
Future Work
• Update of photolysis rate parameters
Future scheme developments (open for discussion)
• UWA (Hong Kong/ Australian emissions) – Chloro-benzenes• Biogenics (Terpenes)• cyclohexanes/cycloalkenes
Development of MCMv3.1 - Aromatics
• Total aromatics form a significant fraction of anthropogenic VOC – from vehicle emissions and solvent use
• Highly reactive compounds with high emissions – substantial contribution to ozone formation
• Degradation schemes for 4 aromatics (benzene, toluene, p-xylene and 1,3,5-trimenthylbenzene) have been updated on the basis of new kinetic and mechanistic data
• Performance of these mechanisms evaluated using detailed photo smog chamber data from the EU EXACT campaigns
Heavily instrumented 200 m3 teflon foil chamber
Long path FTIR – aromatic parent compound, O3, HCHO, HNO3
UV absorption – O3 ; DOAS – NO2, glyoxal
Chemiluminescence – NO ; LIF – OH, HO2
Filter radiometer – J(NO2) GC techniques, HPLC, CO monitor
• EXACT database contains photochemical smog chamber studies on all four mono-aromatics.
• Other experiments on specific key areas of aromatic oxidation, focusing on subsets of the toluene system.
• Where appropriate, results from EXACT have been used to refine the mechanisms.
• This development work on mono-aromatics has been extended to update the degradation schemes of the 12 other mono-aromatics with saturated alkyl side chains in MCMv3.1.
Development of MCMv3.1 - EXACT
• Key areas in which the aromatic mechanisms have changed are:
Lower benzaldehyde yield in the toluene system.
Updated photolysis rates of unsaturated γ–dicarbonyls (ring opening products).
Breakdown of (5H)-furan-2-one (photolysis product of butenedial) has been updated and β–angelica lactone has been replaced by α–angelica lactone to reduce secondary glyoxal formation.
New phenol-type chemistry has been implemented reflecting lower yield for ring opening channel and need for reduced ozone formation from evaluation against EXACT/EUPHORE cresol smog chamber experiments.
Primary aromatic oxidation branching ratios have been adjusted to reflect new reported yields of glyoxal and phenol type compounds (under atmospheric conditions).
MCMv3.1 – Update of Aromatics
MCMv3.1 – Toluene Oxidation
OH
O
OO O O
O O
O O
OH
NO2O O
OH
O O
O O
O OO
O OO O
O
O
O
OH
25% 33%
PHENOL EPOXY PEROXY-BICYCLICRING-OPENING
22% 10%
95% 5%
H-ABSTRACTION
10%
1,4 - ADDITION
p-Methyl-benzoquinone
Benzaldehyde
4-oxo-2-pentenal Butenedial -Angelicalactone
(5H)-Furan-2-one
2,3-epoxy-6-oxo-4-heptenal
OH
O
OO O O
O O
O OO O
O OO
O OO O
OH
NO2
O O
OH
O O
OH
OH O
O
18% 65%
PHENOL EPOXY PEROXY-BICYCLICRING-OPENING
10% 7%
H-ABSTRACTION
7% 73% 20%
MCMv3
MCMv3.1
MCMv3.1 – EXACT Cresol Oxidation • Peak O3 is well simulated with MCMv3.1
• Representation of NO and NO2 profiles is improved
• However, radical yield is too low as rate of cresol oxidation is underestimated
• Results from comparison with EXACT cresol experiments used to adjust hydroxyarene degradation in MCMv3.1
• In MCM3.1a first generation ring retained products are treated in the same way as the original cresol
11 12 13 14 150
100
200
300
11 12 13 14 15
0
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400
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0
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60
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15
20
25
11 12 13 14 15-5.0x10
6
0.0
5.0x106
1.0x107
1.5x107
11 12 13 14 15
0.0
2.0x106
4.0x106
6.0x106
8.0x106
1.0x107
Cre
so
l [p
pb
]
Time [h]
Cresol (04/10/01)
experiment MCMv3 MCMv3.1 MCMv3.1a
O3 [
pp
b]
Time [h]
NO
2 [
pp
b]
Time [h]
NO
[p
pb
]
Time [h]
OH
[m
ole
cu
le c
m-3]
Time [h]
NO
3 [
mo
lecu
le c
m-3]
Time [h]
OH
OH
NO2
O O
OH
O O
OH
OHO
O
OH
OHOH
OH
OH
NO2
O O
OH
O O
OH
OH
OH
NO2
O O
NO2
OH
NO2
O2N
O O
OH
OH
O O
OH
O O
OH
O O
NO2
OH
O O
OH
O O
NO2
OH
O O
OH
O O
NO2
OH
O ONO2
7% 73% 20%
7% 7%73% 73% 20%20%
MCMv3.1 – EXACT Butenedial Oxidation
10 11 12 13 14 15
0
50
100
150
200
250
10 11 12 13 14 15
0
100
200
300
400
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0
20
40
60
10 11 12 13 14 15
0
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40
60
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100
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140
10 11 12 13 14 15
0.0
2.0x107
4.0x107
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8.0x107
1.0x108
10 11 12 13 14 15
0
50
100
150
200
250
But
ened
ial[p
pb]
Time [h]
experiment MCMv3 MCMv3.1
O3
[ppb
]
Time [h]
NO
2 [p
pb]
Time [h]
NO
[ppb
]
Time [h]
OH
[mol
ecul
e cm
-3]
Time [h]
Butenedial (04/07/02)
HO
2 [p
pt]
Time [h]
• Faster removal due to increased photolysis rate in MCMv3.1
• However, OH and HO2 are much lower than measured
• NOxy chemistry poorly understood
• Secondary peak due to formation of PAN
• Ozone simulated well (coincidence?!)
MCMv3.1 – EXACT Benzene Oxidation
• O3 peak again greatly reduced using MCMv3.1
• Good agreement due to increase in phenol yield
• However, increase in ring-retaining products leads to a decrease in oxidising capacity of the system (OH better simulated using MCMv3)
• This is indicative of the general mechanistic problem:
Over prediction of O3 but under prediction of the
system reactivity.
10 11 12 13 14 15 16 17
1200
1400
1600
1800
2000
10 11 12 13 14 15 16 17
0
50
100
150
200
250
300
10 11 12 13 14 15 16 17
0
5
10
15
20
25
30
35
10 11 12 13 14 15 16 17
0
10
20
30
40
50
Ben
zene
[ppb
]
Time [h]
Benzene, low NOx (08/07/02)
experiment MCMv3 MCMv3.1
O3 [p
pb]
Time [h]
NO
2 [pp
b]
Time [h]
NO
[ppb
]
Time [h]
MCMv3.1 – EXACT Toluene Oxidation
• O3 peak still greatly overestimated using MCMv3.1
• increased branching for ring open products (early)
• increased photolysis of unsat. dicarbonyls (early)
• changes in phenol chemistry decreases O3 formation in middle of experiment
• higher “missing” OH for MCMv3.1
• Reduced oxidative capacity consistent with reduced O3 formation potential
10 11 12 13 14 15 16
200
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600
10 12 14 16
0
200
400
10 11 12 13 14 15 16
0
20
40
60
80
100
10 11 12 13 14 15 16
0
50
100
150
Tol
uene
[ppb
]
Time [h]
experiment MCMv3 MCMv3.1
O3 [p
pb]
Time [h]
Toluene, moderate NOx (27/09/01)
NO
2 [pp
b]
Time [h]
NO
[ppb
]
Time [h]
MCMv3.1 – Update of Aromatics
• In general MCMv3.1 shows improved ability to simulate some of the EXACT observations and represents our current understanding of aromatic degradation.
• However, significant discrepancies remain concerning ozone formation potential and oxidative capacity of aromatic hydrocarbon systems:
Peak O3 is simulated well for benzene but over estimated for the substituted aromatics. OH radical production is too low to account for the OH inferred from the rate of loss of the parent aromatic. For a majority of the systems the NO oxidation rate is under predicted. This parameter is linked to the production of O3 and the oxidative capacity of the system.
• Ideas and strategies for resolving these issues have been suggested and additional laboratory and smog chamber experiments are required in order to investigate them further.
MCMv3.1 – Other updates
• New scheme for biogenic hydrocarbon MBO (2-methyl-3-buten-2-ol) added with 93 new reactions, 30 new species
OH
OH
OOH O
O OH
OO OO2N
OC
OH
O O
OH
O
CH2 O O
+ OH
0.67 0.33 0.65 0.35
+NO3 + O3
0.70.3
HCHO
HO2HCHO HO2
HO2
HCHO NO2
MBO
All major new products already in MCM
• Extended list of chloro- and hydrochlorocarbons and 2 hydrobromocarbons
• MCMv3.1 now contains 135 primary emitted VOCs
c.a. 5600 species and 13500 reactions
Mechanism Development – MOST
Multiphase chemistry of Oxygenated Species in the Troposphere
Mechanism Development – MOST
Multiphase chemistry of Oxygenated Species in the Troposphere
• Organic solvents are used in a large number of industrial processes and due to their volatility many are emitted either directly or indirectly into the atmosphere.
• A number of organic compounds employed as solvents at the present time have been shown to have adverse health effects, carcinogenic, mutagenic and reprotoxic properties
• Solvents also undergo complex chemical reactions in the atmosphere, which lead to the formation of compounds which are environmentally damaging, in particular the formation of photochemical oxidants
• It is now well accepted that the switch from additional solvents to oxygenated compounds is inevitable both in terms of toxicity problems and in order to reduce the levels of oxidant formation in the troposphere
• The solvent industry within Europe has targeted a limited range of ethers, ketones, esters and glycols as replacements for traditional solvents
MOST – Key Oxygenates
O
O
N O
O
O
OO
OH
O
O
OO
O
OO
OO
OO
OH
MEK
MIBK
ODVE
DDVE
MVE-2
CHDVE
DVE-2
DVE-3
NMP
DPM
In McM
MOST EUPHORE 2005 - Proposal
“To Carry out carefully designed chamber experiments involving the measurement of reactants, intermediates and products in the
presence of NOx under conditions which simulate ambient tropospheric conditions (NOx and VOC limited)”
(c.f. EXACT 2001-2002)
These experiments will build upon/bring together what we have learned from the MOST chamber studies 2002/2003
OO
MOST EUPHORE 2005 – Model Compounds
• Experiments to be carried out with model compounds
short chain to suppress isomerisation symmetrical known products (easy to calibrate, can we measure them easily?) simplify chemistry separate experiment(s) focussing on important intermediates
(eg. formates)?
• Chosen models: DVE-1 • (Ethylene glycol di-vinyl ether)• Vinyl ether model• Aerosol formation (OH and O3)
MVE-1• (Ethylene glycol mono-vinyl ether)• Vinyl alcohol model• Aerosol formation (OH and O3)
OOH
Explicit mechanism construction
Approaches:
• Construction “by hand” following MCM protocol.
• MECHGEN automatic generation using expert systems techniques used as an initialisation tool.
Problems:
• MECHGEN does not allow for use of experimental values, only SARs are used.
• Implemented SARs/GRs may not be appropriate for these oxygenated species.SARs: Kwok and Atkinson, Atmos. Env., 29, 1685 (1995).
Peeters et al., Chemosphere, 38, 1189, (1999).
GR: Porter et al., J. Phys. Chem. A., 101, 5770 (1997).
Mechanistic Detail – DVE-1 + OH
• Rate constant estimated by analogy
OO
OO
DVE-1CH2=CHOCH2CH2OCH=CH2
Similar reactivity to ether equivalent CH3OCH2CH2OCH3
2.7 × 10-11cm3 molecule-1 s-1
(from Mellouki et al [2004])
O
O
O
Mono-vinyl ether k298 (cm3 molecule-1 s-1)
Methyl vinyl etherMVE
ABSa N/ARRb 4.5 × 10-11
Ethyl vinyl etherEVE
ABSa 6.8 × 10-11
RRb 7.2 × 10-11
AVERAGE 7.0 × 10-11
Propyl vinyl etherPVE
ABSa 1.0 × 10-10
RRb 1.05 × 10-10
AVERAGE 1.025 × 10-10
Technique Reference Estimated kOH (298, cm-3 molecule-1 s-1)
Analogy (see above) 16.7 × 10-11
Group Reactivity (GR) Porter et al. (1997)Peeters et al. (1996)
8.52 × 10-11
Structure Activity (SAR) Kwok and Atkinson (1995) 8.77 × 10-11
DVE-1– degradation scheme 1 (OH)
OO
OHO
O
OO
OO
O
OO
OO
OO
O
OHO
O
OO
O
OO
O
O
OO
OO
O
OO
O
O
OO
OOO
OO
OO
OHO
O
OO
O
OO
O
O
DVE-1
NO2
HO2
+ HCHO
(2*0.053)+(2*0.352) = 0.81
OH Add OH Abs
OH Add
0.095+0.095 = 0.19
DVE1FM
NO2
HO2
DVE1CONE
NO2
HO2
ETHDFM
+ HCHO
NO2
HO2
DVE1CKFM
NO2
HO2
C5O4FMB
OH Abs
OH Abs0.68 0.16
0.16
NO2
HO2
DVE1CKFM
+ HCHO
OH Add
332 OH initiated reactions kOH = 8.77E-11 (SAR)
= 8.52E-11 (GR)
= 16.7E-11 (AN)
DVE-1– degradation scheme 2 (OH)
OO
OO
O
OO
O
O
OO
O
O
OO
OO
O
O O
OO
O O
O
O
O O
OO
O O
O
O
O O
O
O
O
OO
O
O
O
O
O
O O
O
O OO
O O
O
O OO
DVE-1
NO2
HO2
+ HCHO
(2*0.053)+(2*0.352) = 0.81
OH Add OH Abs
OH Add
0.095+0.095 = 0.19
DVE1FM
NO2
NO2
HO2
ETHDFM
+ HCHO
DVE1CKFM
NO2
HO2
C5O4FMB
OH Abs
OH Abs
0.68
0.16
0.16
NO2
HO2
NO2
HO2
OH Abs
NO2
HO2
OH Add
+CHOOCHO
NO2
HO2
OH Abs
NO2
HO2
OH Add
C2DOCHO
+ HCHO
NO2
HO2
OH Abs
+CHOOCHO
CO
NO2
HO2
OH Add
C2DOCHO
+ HCHO
NO2
HO2
OH Abs
+CHOOCHO
CO
NO2
HO2
OH Abs0.14
0.86
+ CO
CCOCHO
+
CCOCHO
CCOCHO
HCHO
NO2
HO2
NO2
HO2
OH Add
+CHOOCHO
HCHO
NO2
HO2
OH Add
+CHOOCHO
HCHO
+CHOOCHO
HCHO
Mechanistic Detail – DVE-1 + O3
• Rate constant estimated by analogy
O
O
Mono-vinyl ether k298 (cm3 molecule-1 s-1)
Ethyl vinyl etherEVE
2.0 × 10-16
Propyl vinyl etherPVE
2.4 × 10-16
• Rate constant measured on 27/5/04 at EUPHORE:
kDVE-1+O3 = [2((2.0 + 2.4)/2)] × 10-16 = 4.4 × 10-16 cm3 molecule-1 s-1
kDVE-1+O3 = 2.5 (± 0.3) × 10-16 cm3 molecule-1 s-1
DVE-1– degradation scheme 1 (O3)
OO
OO
O
OO
O OOO
OO
OO
OH
H
OO OH
O
OO
O OOO
OO
O
OO
OO
DVE-1
*
0.50.5
*+ HCHO +
*
CCOCCHO
+ CO
+ OH+ CO2
HO2
+ CO2
HO2
HO2
0.24 0.20
0.36 0.20
CO
NO
SO2
NO2
H2 O
DVE1FM
DVE1FMMVE-1
CCOCCHO
O3
DVE-1– degradation scheme 2 (O3)
OO
O
OO
O
O OOO
O
OO
O
O
OOH
H
OO
O
OHO
O
OO
O
OO
O
OO
O
O
O OOO
O
OO
O
OO
O
OO
O O
OO
O O
O
O
O
O
O O
DVE1FM
*
0.50.5
*
+ HCHO+
*
+ CO
+ OH
+ CO2
HO2
+ CO2
HO2
HO2
0.24 0.20
0.36 0.20
CO
NO
SO2
NO2
H2O
C2DOCHO
O3
O3
ETHDFM
MOXY2CHO
O3
ETHDFMETOHOCHO
MOXY2CHO
C5O4FMB
CCOCHO CHOOCHO
MVE-1– degradation scheme (OH)
kOH = 1.03E-10 (RR) latest
= 1.20E-10 (RR)
= 6.4E-11 (RR)
= 4.67E-11 (GR)
= 4.80E-11 (SAR)
319 reactions including OH, O3 and NO3
OOH
OHO
OH
OO
OO
OH
OHO
OOH
OO
OOH
OOH
O
OOH
O
O
O OO
OOH
O OO
O
O O
OO
OH
OO
OO
O
O OO
O
O
MVE-1
NO2
HO2
+ HCHO
ETOHOCHO
NO2
HO2
+ HCHO
ETOHOCHO
NO2
HO2
+ HCHO
HO2
0.640.096 0.156
0.105
OH AddOH Add
OH AbsOH Abs
OH Add
NO2
HO2
+CHOOCHO
HCHO
OH Add
NO2
HO2
MOXY2CHO
+ HCHO
j 15
HO2
+ CO
NO2
HO2
Products
HCHO (100%)
ETOHOCHO?
MVE-1– degradation scheme (O3)
OOH
OO
O
OOH
O OOHO
O
OH
O
OOH
H
O OOHO
OOH
OHOH
OOH
OOH
OOH
OOH
O
OO
O
O
O O
OO
O
O
MVE-1
*
0.50.5
*+ HCHO +
ETOHOCHO
*
HOCH2CH2O
+ CO
+ OH+ CO2
ETHGLY
HO2
HOCH2CH2O
+ CO2
HO2
HOCH2CHO
HO2
HOCH2CHO
0.24 0.20
0.36 0.20
CO
NO
SO2
NO2
H2 O
ETOHOCHO
MOXY2CHO
CHOOCHO
O3
O3
kO3 = 1.8 (± 0.7) E-16 latest
Isopleth Plots
Maximum O3 formation as a function of initial NO and VOC concentrations in simulated chamber experiments.
• Identify initial conditions for VOC limited and NOx limited regimes.
• Used to choose conditions for chamber experiments on aromatic compounds (EXACT).
130
260
390 520
650
780910
10401170
13001430
1560 1690
1820
1950 2080
2210
2340
130200 400 600 800 1000 1200 1400 1600 1800 2000
200
400
600
800
1000
1200
1400
1600
1800
2000
NO
/ pp
bv
DVE1/ ppbv
Future Work
Update of Photolysis Reactions
Update of Photolysis Reactions (1)
• Photolysis rates for a core number of reactions (as a function of SZA) have been determined using a two stream isotropic scattering model (on 1st July at 0.5 km, lat. 45oN).
• Variation of j with SZA is described well by the following expression:
j = l (cosX)mexp(-n.secX)
• Some of these parameters are then used to define the photolysis rate of a large number of related species.
• However, the laboratory measured cross sections and quantum yields for these core reactions have not been updated since 1997 and new measurements have also have become available.
Update of Photolysis Reactions (2)
Update of Photolysis Reactions (3)
1.00E-03
1.50E-03
2.00E-03
2.50E-03
3.00E-03
3.50E-03
4.00E-03
0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4
SZA/ Radians
j-v
alu
e/ s
-1
HCHO_R/NO2 MCM
HCHO_R/NO2 TUV4.2
0.00E+00
4.00E-04
8.00E-04
1.20E-03
1.60E-03
2.00E-03
0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4
SZA/ radians
j-v
alu
e/ s
-1
nC3H7CHO/NO2 MCM
HOCH2CHO/NO2 TUV4.2j-(HOCH2CHO) chamber
cs – Atkinson et al. (2002)qy – Atkinson et al. (2002)
j-(n-C3H7CHO) (j<15>) MCM
cs – Roberts and Fajer (1989)qy – Atkinson et al. (1992)
j-(HCHO_R) chamber
cs – Atkinson et al. (2002)qy – Atkinson et al. (2002)
j-(HCHO_R) (j<15>) MCM
cs – DeMore et al. (1994)qy – DeMore et al. (1994)
Update of Photolysis Reactions (4)
• MCM photolysis rate parameters need to be recalculated using up to date spectroscopic and photochemical information.
• A thorough literature review is currently underway
• New calculations will be carried out using the discrete ordinate
radiative transfer models TUV (www.acd.ucar.edu/TUV) and PHOTOL (Jenkin et al. 1997b).
Future Work
New Reaction Schemes
Future Scheme Development
What to do next?
• Biogenics – Terpenes (sequiterpenes)
• Cyclohexanes
• Cycloalkenes
• Chloro-benzenes (Hong Kong and China emissions)
Cyclohexanes: NAEI Speciationcyclohexane 2.579 cyclopentane 0.181propylcyclohexane 2.473 1,2-dimethyl-3-isopropylcyclopentane 0.178c10-cyclo-paraffin 2.249 (2-methylbutyl)cyclohexane 0.154(1-methylpropyl)cyclohexane 2.072 c11-cyclo-paraffin 0.1541-methyl-4-isopropylcyclohexane 2.002 dimethylcyclohexane 0.148butylcyclohexane 1.901 cycloheptane 0.1301-ethyl-3-methylcyclohexane 1.716 c9-cyclo-paraffin 0.124methylcyclohexane 1.423 ethylcyclopentane 0.123methylcyclopentane 1.399 1,2-dimethylcyclopentane 0.122(1-methylethyl)cyclohexane 1.152 1,3-dimethylcyclopentane 0.122(2-methylpropyl)cyclohexane 1.128 methylcyclodecane 0.1011,2,3-trimethylcyclohexane 0.981 1,2,4,4-tetramethylcyclopentane 0.0862,2,3,3-tetramethylhexane 0.758 cyclo-paraffin 0.0771-ethyl-4-methylcyclohexane 0.734 c12-cyclo-paraffin 0.069ethylcyclohexane 0.700 1,1-dimethylcyclohexane 0.0391-ethyl-2,2,6-trimethylcyclohexane 0.580 1,2-ethylmethylcyclopentane 0.0391,4-dimethylcyclohexane 0.574 trimethylcyclopentanes 0.0361,1,3-trimethylcyclohexane 0.533 1,2,3-trimethylcyclopentane 0.0351,2,3,5-tetramethylcyclohexane 0.525 dimethylcyclohexanes 0.0351,1,2-trimethylcyclohexane 0.464 methyltetralin 0.032pentylcyclohexane 0.464 propylcyclopentane 0.028decalin 0.406 1,2,4-trimethylcyclopentane 0.019tetramethylcyclohexane 0.371 1-ethyl-2-methylcyclopentane 0.019octahydro-indan 0.341 1-ethyl-3-methylcyclopentane 0.019C-7 CYCLOPARAFFINS 0.341 cyclooctane 0.0191,1,4,4-tetramethylcyclohexane 0.332 isopropylcyclopentane 0.0191,2,4-trimethylcyclohexane 0.302 methylcycloheptane 0.0191-methyl-1-propylcyclopentane 0.293 trimethylcyclohexanes 0.0171-ethyl-2,3-dimethylcyclohexane 0.263 1,3-ethylmethylcyclopentane 0.0161,2-dimethylcyclohexane 0.259 1,2,4-trimethlycyclopentane 0.009decalin(trans) 0.251 1-methyl-3-isopropylcyclopentane 0.0091,3-dimethylcyclohexane 0.242 hexylcyclohexane 0.0091-ethyl-2-propylcyclohexane 0.240 tertbutylcyclopropane 0.0091-ethyl-1,4-dimethylcyclohexane 0.231 propylcyclohexanes 0.005dimethylcyclopentanes 0.205 butylcyclohexanes 0.003
Building a Hong Kong (HK) Photochemical model
Hong Kong Data Set• Air monitoring network data available for > 5 years,
includes standard MET, NOx, Ozone, CO, SO2, TEOM PM10 and PM2.5, VOC (>200)
• Beginning analysis of datasets to characterise air masses for high pollutant events e.g. measured O3 on 9th June 2004 in excess of 200 ppb
• Identify significant VOC currently not included in the MCM, to enable construction of a HK photochemical model
• Work initiated 1 Dec 2004, with masters student from HK Polytechnic University
Hong Kong Data Set• Emissions and monitoring
Identified missing VOC species• Current MCM species• 135 VOC
• HK Monitoring data> 100 compounds
• 18 halo-compounds• 10 aromatic• 9 halo-aromatic• 38 HC’s (mostly higher alkanes, alkenes, cyclo-alkanes and cyclo-alkenes)• 2 carbonyl compounds
Suggested VOC for expansion of MCM
• New project initiatives require VOC scheme expansion
• Some expansion work begun– Chlorobenzene– 1,5-pentanedial
• Other species identified– Key VOC for HK model work– Biogenics; 1,8-cineole, d-limonene– DMS, DMDS
Some possible candidates identified from various emissions inventories
• Alkylcyclohexanes• 3-heptanone• Ethyl hexanal• Other chlorobenzenes• 1-methyl 4-isopropyl benzene• 3-methylbenzaldehyde• Propyne• Acrolein, vinyl acetate, crotonaldehyde – to be further
expanded as primary VOC (currently secondary species)
