01459_11_00616

ANALYSIS OF ETHANOL IN THE EXHAUST GAS USING GAS CHROMATOGRAPHY

METHODOLOGY PROPOSAL

2

SUMMARY

• Context

•Testing facilities for alternative method

• Synthetic gas tests- Ethanol sample- Sample without ethanol- Ethanol in hydrocarbon mixture- Sample stability

• Methodology development- Retention time determination- Detector linearity- Limit of detection / quantification

• Vehicle tests- Chromatogram from ECE phase (vehicle with E22)- Round Robin Test results

• Conclusion

3

CONTEXT

UNECE is conducting work on the harmonization of light duty testprocedure for homologation (WLTP-DTP).

The Additional Pollutants subgroup is responsible for the development of test procedures for pollutants not currently regulated includingmeasurement equipment and formulae for the measurement for light duty vehicles.

New gasoline fuels are containing substantial amounts of ethanol which is able to be present in the exhaust gas.

The reference way of collecting ethanol from the exhaust gas is based on the use of impingers (solubilisation in water).

The following approach is to propose an alternative technology using bags.

4TESTING FACILITIES FOR ALTERNATIVE METHOD

Preconcentrator Entech Model

7100A

CVSDilution tunnelDilution air

Bag measurement

GC HP 6890 Series

min0 10 20 30 40 50

pA

0

50

100

150

200

250

300

éthène

éthane

propène

propane

isobutane

isobutène+butène 1

1.3 butadiène

butane

2t butène

2c butène

isopentane

pentène 1

pentane

isoprène

2t pentène

2c pentène

2M pentane

3M pentane

hexène 1

hexane

benzène

iso-octane

heptane

toluène

octane éthyl-benzène

m&p xylènes

o xylène

nonane 135 TMB

124 TMB

décane

123 TMB

undécane

dodécane

Measurement of ethanol from bag

5

SYNTHETIC GAS TESTS

6SYNTHETIC GAS TESTS

• Ethanol sample

ZOOM

ETHANOL in NITROGEN

Ethanol in gas phase can be detected by FID

7SYNTHETIC GAS TESTS• Sample without ethanol

no peak detected at the response time of ethanol

ZOOM

AIR ethanol

ZOOM

NITROGEN ethanol

8SYNTHETIC GAS TESTS

37 HC mixture of 150ppb and ethanol in Nitrogen.No interfering peak in ethanol peak area.The peak of “ethanol” is well separated.

• Ethanol in hydrocarbon mixture

Ethanol peak

ZOOM

9SYNTHETIC GAS TESTS

• Sample stability

Successive analysis on the same sample collected in bag.No significant difference observed � No evolution of the samples.

0

500

1000

1500

2000

2500

T = 0 hour T = 1 hour T = 2 hours T = 3 hours

Are

a

100ppb / N2

500ppb / N2

1000ppb / N2

Gas exhaust

10

METHODOLOGY PERFORMANCE CRITERIA

11METHODOLOGY PERFORMANCE CRITERIA

• Retention time repeatability

0

2

4

6

8

10

12

14

16

18

20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Injection number

Tim

e (m

inu

tes)

Very good repeatability2 σ = 0,05 minutes

Ave. = 16,05 min

15.8

15.85

15.9

15.95

16

16.05

16.1

16.15

16.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Injection number

Tim

e (m

inu

tes)

Experimental conditions : different analysis of samples at different concentrations

12

• Detector linearity

100 ppb

1000 ppb

500 ppb

Calibration curve of ethanol

100 ppb

500 ppb

1 ppm

y = 2294,9x + 13,634R2 = 1

0

500

1000

1500

2000

2500

0 0,2 0,4 0,6 0,8 1 1,2

Concentration (ppm)

Are

a

The graph shows a very good linearity of the FID.

Samples obtained from 1ppm Ethanol in Nitrogen bottle and pure Nitrogen using Horiba type GDC-01 dilutor.

METHODOLOGY PERFORMANCE CRITERIA

13

• Limit of detection / quantification

Limit of Detection : LoD = avg. (noise) + 3 x std. dev. (noise)LoD = 60 + (3 x 60)

LoD = 240 ppb

Limit of Quantification : LoQ = 3 x LoD or LoQ = 10 x std. dev. (noise)

LoQ = 3 x 240 or LoQ = 10 x 60

LoQ = 720 ppb or 600 ppb

Noise = 60 ppb

The determination limits is based on the noise measurement (reference DIN32645).Also see WLTP-DTP-AP-02-01a: Definitions

We assumed that LoD and LoQ are low enough to measure ethanol with accuracy

METHODOLOGY PERFORMANCE CRITERIA

14

VEHICLE TESTS ON CHASSIS DYNO

15VEHICLE TESTS ON CHASSIS DYNO

• Flex Fuel vehicle with E22

Example of emissions during ECE phase of NEDC cycle.

min0 10 20 30 40 50

pA

0

50

100

150

200

250

300

éthène

éthyne

éthane

propène

propane

isobutane

isobutène+butène 1

1.3 butadiène

butane

2t butène

2c butène

isopentane

pentène 1

pentane

isoprène

2t pentène

2c pentène

2M pentane

3M pentane

hexène 1

hexane

benzène

iso-octane

heptane

toluène

octane

éthyl-benzène

m&p xylènes

o xylène

nonane

135 TMB

124 TMB

décane

123 TMB

undécane

dodécane

Ethanol

16

• Round Robin Test results (3 labs / 1 vehicle)

These first results show a quite good correlation between the 2 methods

No significant difference on mean value including variability (σ/√n)

VEHICLE TESTS ON CHASSIS DYNO

Results comparison

0

5

10

15

20

25

30

35

40

45

50

1 2 3 1 meanlab

mg/

km

impinger

bag

Laboratory Samplin g technology Analytical technology Ethan ol mg/Km

impinger GC 31,7

bag GC 26,4

impinger GC 32,0

bag GC 47,1

impinger GC na

bag GC 27,8

impinger GC 34,7

bag GC 34,9

ECE phase

2

1

1

3

17

- Feasability of analysis of diluted ethanol collected in bags using gas chromatography is demonstrated.

- Performance criteria

- Linearity of detector is confirmed.- Ethanol is well separated from other compounds present at the exhaust.

- LoD and LoQ are low enough to measure ethanol with accuracy.

- Ethanol stability in bag has been shown.

- Ethanol emissions can be analyzed and quantified according to the regulation.

- First results from RRT are very promising.

� Even if “impingers / GC” is the reference method, the proposed method could be considered as an alternative.

CONCLUSION