effects of low- and high-oxidation dpfs - nanoparticles · effects of low- and high-oxidation dpfs....

Effects of low- and high-oxidation DPFson genotoxic exhaust constituents

13th ETH-Conference on Combustion Generated NanoparticlesZürich, June 22. - 24. 2009

Trojan horse, Harbour of Canakkale, Turkey

What are the products of soot combustion and what are their health effects?


Diesel nanoparticles –Trojan horses for genotoxic compounds

Diesel exhaust contains dozens of carcinogenic, mutagenic, and hormone-like compounds

Nanoparticles penetrate cell membranes (alveoli, blood cells) acting as Trojan horses

Toxic nitrogen oxide emissions

Do DPFs detoxify diesel exhaust?

Problems:


Secondary pollutants of catalytic converter systems

Toxic secondary pollutants - relevant examples

What else can a converter produce besides CO2 , H2 O, and N2 ?


Formation of PAHs in diesel particulate filters?Carcinogenic PAHs from soot combustion?

Nitration of PAHs in particulate traps?From harmless precursors to mutagenic Nitro-PAHs?

TWC-induced formation of ammonia TWCs – the most efficient DeNOx systems on road

Formation of PCDD/Fs in particulate traps?The DPF- an ideal reactor


Formation of NO2 in diesel oxidation catalysts From a reducing to an oxidizing exhaust


The VERT approach

One engine, one test cycle, 14 DPFs, 4 years of work

Do DPFs affect nitrogen oxide emissions?

Nitrogen oxides (NOx , NO, NO2 )

The NOx problem

No effects with respect to engine and vehicle legislation!

The NOx problem


With respect to nitric oxide?

The NOx problem


The NOx problem

With respect to nitric oxide?


The NOx problem

With respect to nitrogen dioxide?


We have 2 filter families, one converts NO2 the other forms NO2 !

The NOx problem


We have 2 filter families, one converts CO the other doesn’t!

Low- / high-oxidation potential DPFs

Carbon monoxide, hydrocarbons, fuel

Both filter families convert HCs



No significant effects on fuel consumption



High-ox filters, convert CO and NO forming NO2 , lox-DPFs don’t!









Formation of NO2 in diesel oxidation catalysts From a reducing exhaust to an oxidizing exhaust


Genotoxic polycyclic aromatic hydrocarbons

Genotoxic PAHs in diesel exhaust

Carcinogenic PAH

1 2

5 6 7 8

1 1

111

1

3 4

11

Pyrene Fluoranthene Chrysene Benz(a)anthracene

Benzo[b]-fluoranthene

Benzo[k]-fluoranthene

Benzo[a]-pyrene

Indeno(1,2,3-cd)-pyrene

Six PAHs are carcinogenic according to the WHO

Carcinogenic PAH

1 2

5 6 7 8

1 1

111

1

3 4

11





Benzo[a]-pyrene


Two are precursors for mutagenic nitro-PAHs

Carcinogenic PAH

1 2

5 6 7 8

1 1

111

1

3 4

11





Benzo[a]-pyrene


Carcinogenesis from benzo(a)pyrene

Oxidative metabolic activation of benzo(a)pyrene by cytochrome P450 enzymes

Benzo(a)pyrene (BP) (+/-) 7,8 BP-oxide

O 78

(+/-) 7,8 BP-dihydrodiol

7

8HO

OH

(+) anti 7R,8S,9S,10R-BP- dihydrodiol-epoxide

78HO

OH

O

9

10

Stereoselective formation of benzo(a)pyrene-DNA-adducts

(+) anti 7R,8S,9S,10R-BP- dihydrodiol-epoxide

78HO

OH

O

9

10

(-) 10R trans-anti-[BP]-triol-N2-deoxy-guanosine-adduct

78HO

OH

9

10NHN

HO

NH

O

N

N

DNA

10NHN

HO

NH

O

N

N

DNA2


Carcinogenic PAHs

For example benzo(a)pyrene?

Genotoxic PAHs

Carcinogenic PAHs

Efficient conversion of benzo(a)pyrene

Genotoxic PAHs

Carcinogenic PAHs

Conversion of all carcinogenic PAHs!

Genotoxic PAHs

Compound specific conversion?

Genotoxic PAHs

6.0 x 10-4 Pa

Carcinogenic PAHs

Compound specific conversion?

6.0 x 10-4 Pa 1.2 x 10-3 Pa

Carcinogenic PAHs

Genotoxic PAHs

1

Volatility and reactivity affect filtration efficiency!

1

6.0 x 10-4 Pa 1.2 x 10-3 Pa 8.5 x 10-7 Pa

Carcinogenic PAHs

2.8 x 10-5 Pa

Genotoxic PAHs







Formation of NO2 in diesel oxidation catalysts From a reducing exhaust to an oxidizing exhaust


Is nitration of PAHs in NOx-rich diesel exhaust an issue?

pyrene

The DPF – a chemical reactor

Nitration of PAHs

pyrene 1-nitropyrene

In one step from a harmless precursor to a mutagen?

The DPF – a chemical reactor

Nitration of PAHs

Genotoxic Nitro-PAHs

DPF-induced nitration of PAHs

Formation of 1-nitronaphthalene

NO O

1



Formation of 1-nitronaphthalene but conversion of 2-nitronaphthalene

NO O

1O

N

O

23.2 x 10-2 Pa



Formation of 1-nitronaphthalene but conversion of 2-nitronaphthalene

NO O

1O

N

O

23.2 x 10-2 Pa

For comparison

1.2 x 10-3 Pa



What about 3-ring Nitro-PAHs?

O

NO3



Formation of 9-nitrophenanthrene but some conversion of 3-nitrophenanthrene

9N

O

O

O

NO3



Nitration is regioselective – peri-positions are more reactive.

NO O

19

NO

O

ON

O

2

O

NO3


What about mutagenic Nitro-PAHs?

3

O

N

O1

ON

ODPF-induced nitration of PAHs


What about less volatile Nitro-PAHs?

NO O

9

4

O

NO

16

3

O

N

O1

ON

ODPF-induced nitration of PAHs

Substantial variation among DPFs, but similar nitration chemistry

NO O

19

NO

O

ON

O

2

O

NO3



Formation and release of 1-nitronaphthalene and 9-nitrophenanthrene is frequent

NO O

19

NO

O

ON

O

2

O

NO3



Do DPFs detoxify diesel exhaust?



Its a long way from diesel soot to CO2 and H2 O!

Results:

Conclusion:

Current DPF technology lowersemissions of genotoxic compoundsSome nitro-PAHs are formed de novo, others areconverted

VERT®-approved DPF are efficient sinks for soot nanoparticles and genotoxic compoundswith moderate risks for secondary poisoning

Some DPFs form NO2, others convert it

DPFs to not abate the NOx problem, some evenenhance it!


Wall-flow DPFs eliminate solid nanoparticles

About 7 m3 exhaust (3 min operation of a 3.0 L Euro-3 engine (100 kW)


Today, wall-flow DPFs are best available technology to detoxify diesel exhaust. Are combined DPF-DeNOx systems the future?


Thanks: VERT team: Andreas Mayer, TTM, NiederrohrdorfJan Czerwinski, Sandro Napoli, Tobias Neubert, Thomas Hilfiker, Jean-Luc Petermann, Yan Zimmerli, Uni. Appl. Sci., Biel.Markus Kasper, Adrian Hess, Thomas Mosimann, Matter Engineering, WohlenHans Jaeckle, Urs Debrunner, Oliver Schumm, Intertek Caleb Brett, Schlieren.

Empa colleagues: Brigitte Buchmann, Thomas Bührer, Anna-Maria Forss, Urs Gfeller,Maria Guecheva, Peter Graf, Roland Graf, Erika Guyer, Regula Haag, Peter Honnegger,Judith Kobler, Martin Kohler, Peter Lienemann, Alfred Mack, Peter Mattrel, Martin Mohr, Joachim Mohn, Christof Moor, Peter Schmid, Cornelia Seiler, Andreas Paul, Heinz Vonmont, Thomas Walter, Max Wolfensberger, Daniela Wenger, Adrian Wichser,Markus Zennegg, Kerstin Zeyer.

Governement: Giovanni D’Urbano, Max Wyser, Gerhard Leutert, Martin Schiess, Swiss Fed. Office for Environment, Bern

Filter- & catalyst manufacturers: >30 different diesel particulate filter systems

Traugott Sandmeyer (1854-1922)


effects of low- and high-oxidation dpfs - nanoparticles · effects of low- and high-oxidation dpfs....

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