1

Ionic and Organic Species in PM

Emissions from Advanced Technology

Heavy-Duty Diesel Vehicles

Alberto Ayala, Shaohua Hu, Jorn Herner, M.-C. Oliver Chang, William Robertson, John Collins, Tao Huai,

and Paul Rieger

California Air Resources BoardOctober 23, 2008

27th AAAR Annual ConferenceOct 20-24, 2008, Orlando, Florida, USA

Courtesy of D. Su, Fritz-Haber Institute

2

Acknowledgements:

2005-01-3800

CO-Investigators: CARB’s Monitoring and Laboratory Division, CARB’s Mobile Source Control Division, University of Southern California, UC Davis, U of Wisc.

Co-Sponsors:

In Kind Contributors:

3

NOX and PM Retrofits Investigated 1

Heavy-Duty Vehicles

Diesel Particle Filter

NOX Catalyst+ +

Catalyzed Filter

DOC

UncatalyzedFilter

UncatalyzedFilter

DOC

Catalyzed Filter

Urea

OxidCat

VanadiumSCR

1. Herner et al. 2007. Towards 2010 NOx and PM emission Levels: Overview of CARB's Investigation of Advanced Heavy-duty On-road Vehicle Retrofits and Other Technologies. 26th AAAR Annual Conference, September 24-28, 2007, Reno, NV

Baseline vehicle = no retrofit

Urea

OxidCat

Zeolite SCR

• One vehicle tested with DPF + SCR

• DPF + SCR is of special interest as it represents most advanced technology for meeting 2010 standards

• SCRT® systems used in this project are development prototypes not commercial units

4

Particle filter is game-changing technology. It ach ieves significant PM emission reductions from diesel engi nes

PM Mass Emissions [mg/mi]

Veh#1, Baseline

Veh#1, CRT

Veh#1, V-SCRT

Veh#1, Z-SCRT

Veh#2, DPX

Veh#3, Horizo

n

Veh#4, CCRT

mg/

mi

-5

0

5

10

15

20

25

30

150300450600750

Cruise at 50mphUDDS

Not

Mea

sure

d

PM retrofits yield greater than 90% reduction in PM emissions

Baseline Diesel Sample DPF+SCR SampleAgglomerates Clean as Blank

SEM images courtesy of D. Su, Fritz-Haber Institute

5

Experimental Setup @ CARB’s Emissions Lab

Exhaust from Testing Vehicles

Dilution Air

Filters

(+ vapor traps)

PM, PAHS,Nitro-PAHs,Ions, Trace elements,EC/OC,

Mutagenicity

NanoMOUDI

PM, organics and Ions

HiVolSampler

Organics, Ions, Redox

activity

ThermaldenudedSample

Metals, Ions, Redoxactivity, CPC

Cartridges

Carbonyls

Particle Characterization

EEPS, DMS, multiple CPCs,

PAS, EAD

FTIRN2O, NH3

BagsGases, VOCs

Sioutas Impactor @

V2O5

CVS TunnelQ=2600 or 1600 cfm

Sample Types Filter MediaFlow RateRange (lpm) Method Instrument

organic and elemental carbon Quartz fiber 38-40

IMPROVE_A, DRI Model 2001

Ionic species PTFE filter 40-45 IC Dionex

PAH TX60 75-80 GC-MSASE-

GC/MS

6

• EC (i.e., diesel soot) is not dominant emission. Mo re OC than EC

• All retrofits yield significant reductions of EC an d OC

• Elevated sulfate and ammonium are observed for retr ofits that also exhibit high particle nucleation

T ra n s ie n t U D D S

Io n s

Nitrate

Sulfate

Sodium

Am monium

PotassiumOC EC

mg/

mile

0 .0 1

0 .1

1

1 0

1 0 0

1 0 0 0

1 0 0 0 0

B a se lin eC R TV -S C R TZ -S C R TD P XH o rizo nC C R T

Z-SCRT shows comparable sulfate and ammonium as baseline

Reduction

Bel

ow d

etec

tion

Bel

ow d

etec

tion

Bel

ow d

etec

tion

Bel

ow d

etec

tion

Ions and Carbon Emissions

7

Relative Fraction of Ions and Carbon Emissions

• EC/OC about equal fractions of PM emissions for bas eline vehicle

• Sulfate is dominant for most retrofits during cruis e operation. 40-50% of PM is sulfate for retrofits with significant nucleation events (e .g. CRT, SCRTs and DPX)

• OC dominates PM emissions from most retrofits when vehicle operates over transient cycle

0%

25%

50%

75%

100%V

eh#1

, Bas

elin

e

Veh

#1, C

RT

Veh

#1, V

-SC

RT

Veh

#1, Z

-SC

RT

Veh

#2, D

PX

Veh

#3, H

oriz

on

Veh

#4, C

CR

T

Veh

#1, B

asel

ine

Veh

#1, C

RT

Veh

#1, V

-SC

RT

Veh

#1, Z

-SC

RT

Veh

#2, D

PX

Veh

#3, H

oriz

on

Veh

#4, C

CR

T

EC

OC

Potassium

Ammonium

Sodium

Sulfate

Nitrate

Cruise at 50mph UDDS

not

mea

sure

d

8

Charging Balance (Anions/Cations)

Transient-UDDS

Veh#1

, Bas

eline

Veh#1

, CRT

Veh#1

, V-S

CRTVeh

#1, Z

-SCRT

Veh#2

, DPX

Veh#3

, Hor

izon

Veh#4

, CCRT

Ani

on/C

atio

n

0

1

2

3

4

5

6

SulfateBi-sulfate

Cat

ions

=0

a. Anions: sulfate and nitrateb. Cations: ammonium, potassium and sodium

– Particles from some retrofits (e.g., CRT & Horizon) are more acidic (anions/cations > 1)

– Suspect formation of nitric acid and sulfuric acid

– Transient cycle increases acidity

– Emissions from baseline and other retrofits appear to be neutralized

9

Preliminary Results - Particle Phase PAHs 2

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Total PAH vapor phasePAH

SemiVol-PAH P-bound-PAH

Em

issi

on r

ate

in u

g/ho

ur

Baseline/1000 V-SCRT Zeo-SCRTCRT Englehart DPX HybridHorizon

UDDSUDDS

2. Chang et al. 2008. Air Toxic Emissions from HD Diesel Vehicles Equipped with NOx and PM Retrofits. 18th CRC On-Road Emissions Workshop, March 31 - April 2, 2008, San Diego, CA

Baseline divided by

1000

10

IDLE

1,3

Butad

iene

Benze

ne

Toluen

e Eth

ylben

zene

m,p

-xyle

ne

styre

ne

o-xy

lene

mg/

hr

1

10

100

1000

UDDS

1,3

Butad

iene

Benze

ne

Toluen

e Eth

ylben

zene

m,p

-xyle

ne

styre

ne

o-xy

lene

mg/

mile

1e-5

1e-4

1e-3

1e-2

1e-1

1e+0

1e+1

1e+2

BaselineCRTV-SCRTZ-SCRTDPXHorizonCCRT

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Not

Mea

sure

d

Air Toxics (Benzene, Toluene, Ethylbenzene and Xylen e )

Cruise and UDDS Cycles

• Greater than 70% reduction of BTEX by all retrofits

• For some emissions are below background

a. No measurements for CRT and CCRT during idle operationb. Values not displayed are below the levels of filtered ambient air

Idling• Greater than 70% reduction of

BTEX by most aftertreatmentdevices

• But, increased levels of Benzene observed from DPF+SCR retrofits

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Final Remarks• Well-functioning retrofits are performing as designed. They reduce emissions

significantly (EC/OC, PAHs, BTEX).

• No surprises. Just a few remaining questions.

• Some retrofits are prototypes. So there is room for optimization in production-ready systems

• Chemical composition of PM emissions is altered by retrofits

• Elevated sulfate and ammonium correspond to retrofits that also exhibit high particle nucleation

• Study presents significant challenges for analytical analysis due to very low mass emissions from retrofit-equipped vehicles

• Future work:– Complete analysis/publication of results for heavy-duty vehicles– Study passenger cars fueled by diesel, E85, CNG, gasoline, biodiesel

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See Also at AAAR08: • 8D.5 Wednesday 4:15pm: Novel Approaches for Speciation of Platinum and Vanadium in Mobile

Source Emissions.

• 9A.1 Thursday 9:20 am: Chemical Speciation of PM Emissions from Heavy-Duty Diesel Vehicles Equipped with DPF and SCR Retrofits.

• 9A.26 Thursday 9:20 am: Elements Emitted from Advanced Technology Heavy Duty Diesel Vehicles.

• 10A.3 Thursday 11:15am:Toxicity of Particulate Matter from Heavy-Duty Vehicles Retrofitted with Emission Control Technologies.

THANK YOU

Questions?

More about vehicle emissions research program by CARB:

http://www.arb.ca.gov/research/veh-emissions/veh-emissions.htm