Arnal et al - GPT Thermo-Chemical Processes Group

Characterization and reactivity with NO and O2 of diesel engine soot and analogues

Financial support:

• COST Action CM0901, Obra Social CAI through Programa Europa and Valeo Térmico,S.A.

• European Social Fund, MINECO (Project CTQ2012-34423) and Aragón Government

• Ministero dello Sviluppo Economico within the “Accordo di Programma CNR-MSE, Gruppo Tematico Carbone Pulito-Fondo and NIPS-Seed Project 2009-IIT

COST ACTION CM0901. Joint Working Group Meeting “Soot and PAHs”

1. Introduction and objectives

2. Characterization techniques and reactivity experiments

3. Results

3.1 Characterization of the different kinds of soot

3.2 Reactivity of soot towards O2 and NO

4. Conclusions


1.1. Introduction and objectivesIntroduction and objectives


3. Results



4. Conclusions


• Improved quality and reformulation of diesel fuels

• Interaction of soot with gases like oxygen or NOx.


Printex-U PUPUSRM1650b SRMSRM

DS6DS6DS9DS9

Diesel soot DS14DS14DS17DS17DS19DS19

Soot Soot characterizationcharacterization

andandreactivity reactivity

(with O2 and NO)

EGR from an engine

bench

EGR from vehicle

(NIST)


•• Soot characterizationSoot characterization: elemental analysis, BET surface area, FESEM, TEM, FTIR-ATR, TGA, ICP-MS, GS-MS, UV-vis and fluorescence spectroscopy.

• The study of the reactivity of different reactivity of different kinds of soot and analogueskinds of soot and analogues: experiments of oxidation and NO interaction.



2.2. Characterization techniques and reactivity experimentsCharacterization techniques and reactivity experiments

3. Results



4. Conclusions


Characterization techniques:Characterization techniques:PROPERTIESPROPERTIES

Elemental analysis C, H, N assessmentPhysical adsorption Specific surface area

FESEM Morphology and topography of soot surface

TEM Soot internal structureXRD Crystalline structure

Raman spectroscopy Structural order/disorder of soot samples

FT-IR spectroscopy Chemical functionality of soot surface

TGA Thermal resistance studyICP-MS Element trace determination

GC-MS Qualitative analysis on adsorbed species on soot surface

UV-visible spectroscopy Aromatic moietiesFluorescence spectroscopy Aromatic moieties


Experimental setExperimental set--up for reactivity experiments:up for reactivity experiments:


Experiments:Experiments:




3.3. ResultsResults



4. Conclusions


Elemental analysisElemental analysis

– High C content.

– High H content is related to:

• high number of available active sites and to high reactivity of the material

• the presence of functional groups and/or adsorbed molecules

– Samples treated at 1273 K:

• very low H content graphitic structures

• removal of functional groups and adsorbed molecules

ICPICP--MSMS – Major elements found:• Calcium• Iron• Phosphorus• Zinc

0

20

40

60

80

100

1 2 3 4 5 6 7

C

O

H

N

PU SRM DS6 DS9 DS14 DS17 DS19

% wt.


FTIRFTIR--ATRATR TGATGA

300 400 500 600 700 800 900 1000 1100 12000

102030405060708090

100

% W

eigh

t

Temperature (K)


Water evaporation

Hydrocarbondesorption

anddecomposition of oxygenated functionalities

Oxidation of carbonaceous

core

3600 3200 2800 2400 2000 1600 1200 800

Inte

nsity

(a.u

.)

Wavenumber (cm-1)


C O

C C

O-H C-H C -H

C -O

– High quantity of oxygenated functionalities

(mainly C=O from esthers and ketons) and

aliphatic chains

– Weight losses in oxidative environment:• < 473 K water evaporation• 473 – 673 K HC desorption, decomposition of

oxygenated functionalities• 673 – 1173 K oxidation of carbonaceous core


UVUV--visible spectroscopyvisible spectroscopy Fluorescence spectroscopyFluorescence spectroscopy

250 300 350 400 450 500

Nor

mal

ized

abs

orba

nce

(a.u

.)

Wavelength (nm)


250 300 350 400 450 500 550 600

Nor

mal

ized

fluo

resc

ence

inte

nsity

(a.u

.)

Wavelength (nm)


DCM extract:DCM extract:

−Small quantity of PAHs

−Light PAH of 2-4 rings

GCGC--MSMS confirmed the presence of aliphatic chains (confirmed the presence of aliphatic chains (CC1010 -- CC2323) and some PAHs (2) and some PAHs (2--4 rings)4 rings)


FESEMFESEM

-- Inner coreInner core: fine particles and random carbon layers with disordered structures.

- Outer shellOuter shell: microcrystallites with periodic orientation.

TEMTEMPU SRM

DS9 DS17

Mean diameter (nm)Mean diameter (nm)

FESEMFESEM TEMTEM

PU 37 40SRM 32 31DS9 27 24DS17 24 25

PU SRM

DS9 DS17

- Particles joined together to create particle aggregates of different sizes.

Structure of DS17DS17 more typical to char or amorphousamorphous samples (also found by XRDXRD and

Raman spectroscopy), Raman spectroscopy), confirming TG trend (less compact and more defective structure)


SootSoot--OO22 reactivityreactivity

0 1 2 3 4 5 6 7 8 90

100200300400500600700800900

1000

CO

(ppm

)

Wc (mg)


0 1 2 3 4 5 6 7 8 90

50

100

150

200

250

300

350

400

CO

2 (ppm

)

WC (mg)


O2 (g) + bC (s) cCO (g) + dCO2 (g)


SootSoot--OO22 reactivityreactivity

0 1000 2000 3000 4000 5000 6000 70000,00,10,20,30,40,50,60,70,80,91,0

XC

Time (s)


(s)(s)PU 2941

SRM 4545DS6 3413DS9 4425

DS14 8850DS17 2198DS19 4717

Macroscopic Model type I, in regime IIMacroscopic Model type I, in regime II: controlled by chemical reaction and pore diffusion.

3/111 CXt

↓ ↑ reactivity

↑ H content, disordered structure (TEM, XRD, Raman spectroscopy)


0 1 2 3 4 5 6 7 80

100

200

300

400

500

600

700

800

900

CO

(ppm

)

WC (mg)


0 1 2 3 4 5 6 7 80

100

200

300

400

500

600

700

800

900

CO

2 (ppm

)

WC (mg)


NO (g) + b’C (s) c’CO (g) + d’CO2 (g) + e’N2 (g)

SootSoot--NO reactivityNO reactivity


0 1000 2000 3000 4000 5000 6000 70000,00,10,20,30,40,50,60,70,80,91,0

XC

Time (s)


(s)(s)PU 4464

SRM 3861DS6 2639DS9 2049DS14 9434DS17 1988DS19 2793

For a given carbon weight of 3.5 mg:XXNONO

PU 0.1381SRM 0.1670DS6 0.2198DS9 0.2794DS14 0.1032DS17 0.3690DS19 0.2676

0 1 2 3 4 5 6 7 80

100200300400500600700800900

100011001200

NO

red (p

pm)

WC (mg)


SootSoot--NO reactivityNO reactivity

i,NO

o,NOi,NONO C

CCX

NO reduction: Reactivity with NO:

Macroscopic Model type I, in regime IIMacroscopic Model type I, in regime II: controlled by chemical reaction and pore diffusion.




3. Results



4.4. ConclusionsConclusions


Soot characterization:

Chemical composition:o Soot mainly composed by C (similar among PU, DS6 and DS9; and similar among

SRM, DS14, DS17 and DS19), with high H content for DS14, DS17 and DS19

Adsorbed compounds: o All samples presented small quantity of light PAHs (2-4 rings) while SRM, DS14,

DS17 and DS19 shown high quantity of aliphatic chains

Physical properties:o Primary particle diameter range: 24 - 40 nmo DS17 very disordered structure (TEM, XRD, Raman spectroscopy)


Reactivity with O2 and NO:

o DS17 the most reactive material with the lowest , and the highest NO reduction for a given WC.

o DS14 the least reactive material with the highest , and the lowest NO reduction for a given WC.

Similarities between commercial/standard materials and real diesel soot:

o PU similar to DS6 and DS9o SRM similar to DS14, DS17 and DS19

[email protected]

Characterization and reactivity with NO and O2 of diesel engine soot and analogues

Financial support:

• COST Action CM0901 and Obra Social CAI through Programa Europa

• European Social Fund, MINECO (Project CTQ2012-34423) and Aragón Government

• Ministero dello Sviluppo Economico within the “Accordo di Programma CNR-MSE, Gruppo Tematico Carbone Pulito-Fondo and NIPS-Seed Project 2009-IIT

Documents

Arnal et al - GPT Thermo-Chemical Processes Group