STUDY OF SOURCE ATTRIBUTION OF UNSATURATED

HYDROCARBONS FOR OZONE PRODUCTION IN THE

HOUSTON-GALVESTON AREA WITH THE EXTENDED

SAPRC99 CHEMICAL MECHANISM

Beata CzaderDaewon W. Byun

Department of Chemistry &Institute for Multidimensional Air Quality Studies (IMAQS)

Propylene (Ton/Day)

MotivationThe metropolitan area of Houston is home to

the largest grouping of petrochemical industrial plants in the United States.

27.6 billion pounds of ethylene produced –

52% of national capacity

10.9 billion pounds of propylene produced –

63% of national capacity

TexAQS 2000 demonstrated the importance of HRVOC for ozone formation especially ethylene, propylene, 1,3-butadiene, and other butenes

OBJECTIVES

Improve the resolution of the chemical mechanism – SAPRC99ext mechanism

Develop emission processing scheme for SAPRC99ext

Study the relationship between measured formaldehyde spikes and alkene

emissions

Study the differences in reactivity obtained with different chemical mechanisms

Compare AQM simulations based on different emissions inventories

APPROACH

SAPRC99 and SAPRC99ext emission lumping

Speciation profiles

Ncpd

nnininpnpi MWreacallocxmfxmol

1,,,, /**

SAPRC99 SAPRC99ext

ETHENE ETHENE

OLE1

OLE2

PROPENE

BUTADIENE13

OLE1

OLE2

Gipson, G. L.: Speciation in Models-3/MEPPS and Models-3/SMOKE. 2001

Reactions implemented in the SAPRC99ext mechanism

PROPENE + OH, O3, NO3, O(3P) BUTADIENE13 + OH, O3, NO3, O(3P)

Source: Carter, W., 2000. Documentation of the SAPRC-99 chemical mechanism for VOC reactivity assessment.

OLE1 → 73.2 (SAPRC99) → 85.0 (SAPRC99ext)

OLE2 → 75.8 (SAPRC99) → 77.0 (SAPRC99ext)

Molecular Weight

Source: Carter, W., 2000, Programs and Files Implementing the SAPRC-99 Mechanism and its Associated Emissions Processing Procedures for Models-3 and Other Regional Models.Carter, W., 2004, Documentation of speciation preprocessor programs for SMOKE.

R1 R2 SAPRC99 SAPRC99ext Propene/Butadiene

OLE1 OH 32.3*10-12 34.65*10-12 26.3*10-12

OLE2 OH 63.1*10-12 63.2*10-12 66.6*10-12

Reaction constant k(T)=A exp(-E/RT) at 298 K (cm3 · molec-1 · s-1)

Modeling Data and Methodology

1. NEI 1999, SAPRC99, 2. NEI 1999, SAPRC99ext3. NEI 1999, CB-44. TEI 2000 (base4a.pto2n2), SAPRC995. TEI 2000 (base4a.pto2n2), SAPRC99ext6. TEI 2000 (base4a.pto2n2), CB-4

Simulated episode: Aug. 23 – Aug. 31, 2000

SMOKE 1.4 CMAQ 4.2.2

The comparison of emissions for SAPRC-99 and SAPRC-99 extended

SAPRC99 SAPRC99 ext SAPRC99 SAPRC99 ext

65

60

55

50

45

40

35

OLE

1+P

RO

PE

NE

_sap

rc99

ext

65605550454035OLE1_saprc99 (kmol/hr)

TEI 120

100

80

60

40OLE

2+B

UT

AD

IEN

E13

_sap

rc99

ext

120100806040OLE2_saprc99 (kmol/hr)

TEI

Emission rates with SAPRC99 and SAPRC99ext

60

50

40

30

20

10

PR

OP

EN

E [

kmo

l/hr]

8/23 8/24 8/25 8/26 8/27 8/28 8/29 8/30 8/31 9/1Date

NEI_SAPRC99ext TEI_SAPRC99ext

160

120

80

40

OLE

1 [k

mol/h

r]

8/23 8/24 8/25 8/26 8/27 8/28 8/29 8/30 8/31 9/1Date

NEI_SAPRC99 NEI_SAPRC99ext TEI_SAPRC99ext TEI_SAPRC99

National Emission Inventory NEI, 1999

Texas Emission Inventory TEI, 2000, base4a.pto2n2 (IMPUTED)

TEI, OLE1

NEI, OLE1

TEI, OLE1-PROPENENEI, OLE1-PROPENE

TEI, PROPENE

NEI, PROPENE

Process Analysis results with SAPRC99ext

TEI

NEI

TEI

20.0 4.0 0.44.0

CMAQ simulation results for ozoneSAPRC99 SAPRC99ext

NEI

TEI

Comparison of simulation results with observed data

(at the surface)

La Porte side

HCHO

O3

Williams Tower

HCHO data for HRM-3 obtained from P. K. Dasgupta

HRM-3

Clinton80

60

40

20

0

Co

nc

[ppb

C]

8/23 8/24 8/25 8/26 8/27 8/28 8/29 8/30 8/31Date

observed NEI TEI

Clinton side Propene

100

80

60

40

20

0

Co

nc

[pp

bC

]

8/23 8/24 8/25 8/26 8/27 8/28 8/29 8/30 8/31Date

observed NEI TEI

Clinton side 1,3 - Butadiene

Preliminary Conclusions

Among the anthropogenic emissions ethene and propene contribute most

to formaldehyde production. The contribution of 1,3-Butadiene and other

olefins is not significant.

With TEI, simulated concentrations of ethylene, propylene and other

olefins are higher than observed values, at the surface.

With NEI, olefin concentrations match observed values for some days of

the episode and are much lower for other (Aug. 23, 24, and 25).

Simulated values of 1,3-Butadiene match measured values at the surface,

with both TEI and NEI.

The differences in ozone production between SAPRC99 and SAPRC99ext

are around 1 ppb, as expected, however extending the SAPRC99

mechanism helps to identify the source-receptor relationship better.