ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China
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Transcript of ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China
UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
ICMMM2011 , 8-10 Dec 2011, Zhengzhou, Chinahttp://www.icmmm.net/ 2012.9.21-23 Beijing
UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
Zeolite thin films as new materials for chemically active layers in
magneto-elastic sensors
D. Kouzoudisa, V. Nikolakisb, Th. Baimposb
a Editor-in-chief, Sensor LettersUniversity of Patras, Greece
b FORTH, Patra Greece
ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China
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Outline• Zeolite films – excellent active sensing layers - Review• Magnetoelastic (ME) resonance sensors• Volatile Organic Compounds (VOC)• Detection of VOCs with Zeolite/ME sensors
Zeolite thin films as new materials for chemically active layers in magneto-elastic sensors
ME sensorZeolite film
VOC
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Zeolites
(Review on Sensing Applications)
ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China
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• Inorganic, crystalline, aluminosilicate materials• Chemically and thermally stable • Industry: Excellent catalysts, molecular sieves, ion-exchangers, water softeners •170 different types, about 17 of them commercial interest
Zeolites
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• Consist of interconnected SiO2 and AlO2 tetrahedra & Cations+
• Tetrahedra form 3D frameworks with linked channels down to molecular level• High porosity, pores fixed down to nm sizes -> gas sensing• Exceptionally high specific-surface-area
400 m2/gr (two large apartments in one gram !!!)
Zeolites
+ Na++ =
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Zeolite Building blocks SiO2 tetrahedra
Chemical formula SiO2?Tetrahedra connected at cornersEach Oxygen is shared by 2 tetrahedra All corners are connected4 × ½ = 2 O atoms →
Schematically, oxygen are shown as straight lines (bonds) and Si at the cornersAll corners are connected → 4 lines from each Si
O SiSi
O Si
Si
O O
Sihttp://www.icmmm.net/
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Si
SiO
Zeolite - Silicalite (MFI)
1-D channels
All bonds are homopolar → no polarity in the crystal →Extremely hydrophobic
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Zeolite - Silicalite (MFI)
(SiO2)
Simplifiedplanar view
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Two DifferentBuilding blocks
SiO2
The Al cannot form heteropolar bond with one O =>Local electronegativity =>Extra cation Na+, Ca++ trapped =>Polarity in the crystal
AlO2
BrokenBond
Na+
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Zeolite LTA, Si/Al = 1
Na+ [(SiO2) (AlO2)- ]. zH2O
Na
Simplifiedplanar view
+
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Zeolite LTA, Si/Al = 1
Na+ [(SiO2) (AlO2)- ]. zH2O
Na
Simplifiedplanar view
+
+
+
+
+
++
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Zeolite LTA, Si/Al = 1
LTA
Cations cause polarity → attract polar molecules (water, CO2)
+
+
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Xm+y/m [(SiO2)x (AlO2)-
y ]. zH2O
(Na+, Ca++)
Zeolite FAU, Si/Al ≠1
FAU
++
+
+
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Si x% - Al y%Cations Na, CaPolar3-D entangled channels
FAURing 12
MFISi 100%non-polarHydrophobic1-D channels
Ring 10
LTASi 50% - Al 50%Cations Na, CaPolar3-D straight channels
Ring 8
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Useful Zeolite properties for sensing
• Trap selectively gas molecules of the right size• Trap selectively gas molecules of the right
shape• Trap selectively gas molecules of the right
polarity• Highly polar materials, ion conductors and ion
exchangers• Al+3 acidic site: catalyze a number of chemical
reactions • Room temperature operation• High specific surface
Molecular Sieving for octane-isomers LTA
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Main Disadvantages:
• Polar Zeolites adsorb humidity, need initial degassing• Slow Diffusion (gas out)
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Mass LoadFilm PropertiesFilterGuest/HostComposite
Basically there are 5 different ways on how to use Zeolites for Sensing Applications:
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microbalancezeolite
Mass Load: Selective adsorption of certain molecules → Microbalance senses mass load
QCM, SAW, Magneto-elastic,Microcantilever
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zeolite
Film: Selective adsorption of certain molecules → Redox interactions with cations → Change of film property
Impedance SpectroscopyResistive SensorsCapacitiveOpticalV
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sensor
zeolite
Filter : Selective adsorption of certain molecules → make it to the sensitive layer (+ catalysis )
sens. layer MOS silicon sensors
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Guest/Host: Certain molecular complexes pinned at zeolite sites act as sensing centers such as fluorophores, dyes
zeolite
complex
FluorescentOptical sensors
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Composite: Zeolite placed inside a matrix in order to improve its sensing properties
matrix
zeolite
Conductive Polymer sensors
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Type Sensor Sensed GasMass load QCM
SAWmicrocantilever
NO, SO2, DMMPS. acetonepentane, hexane, H2O, NH3
freon
Film proton conductive zeolitesNa+ ion conducting zeolites
NH3
hydrocarbonsmethanol, 2-propanol and 3-pentanol
Guest/host Ru(II) complex/zeolitemethylene blue/zeoliteLiCl/zeolites
O2, H2O
Filter magnetoelasticoptical fibersurface plasmonresonance
O2, CO, CO2, organics, butylamine
Composites polyaniline/zeolitezirconia/zeoliteplatinum/Y-zeolitesSrTi1-xFexO3/zeoliteTiO2/zeoliteSnO2/zeolite
CONOC4H10, CO and H2
hydrocarbonsalkaneshydrocarbonsmethane, propane, and ethanolXiaowen Xu, Jing Wang, and Yingcai Long, Sensors 2006, 6, 1751-1764
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Zeolite based gas sensors
Detection of Sensor type Zeolite
Detection principle
Freon-12 PZT balance MFI Adsorption mass load
A cetone QCM MFI Adsorption mass load
Humidity W ater 500 °CAmmonia
Ohmic HEUH MFIH BEA
Ionic conductivity
Hydrocarbons Electroch. cell NaMFI Ionic conductivityNitric oxide Electroch. cell NaFAU Catalysis
Pentanoic acid Optical fiber MFI adsorption induced reflectivity changeshttp://www.icmmm.net/
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Electrical resistance of chromium titanium oxide (CTO) sensors overlaid with zeolitesDetection ethanol / isopropanol in dry air operated at 4000C
CTOzeolite
BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011
V
ethanol
isopropanol
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Typically ethanol / isopropanol react with O-- ions, producing CO2 and releasing electrons => Change of resistanceThey give similar signal because of same functional group
CTO
V
ethanol
isopropanol
BareSensor
O--
BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011
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The zeolite can make the difference acting as both as a shieve and catalyst enhancing the reaction
CTOzeolite
V
ethanol
isopropanol
BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011
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ethanol
isopropanol
BareSensor
+LTA zeolite
Sens
or S
igna
l
Time
BareSensor+LTA
BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011
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Hydrocarbon C3H8 Gas Detection – Impedance sensor
Gunter Hagen and Ralf Moos, SENSOR LETTERS 9, 110–113, 2011Z
The ionic conductivity is measured by impedance spectroscopy
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change in color upon protonation /deprotonation of dye molecules intercalated into the zeolite
S. Sohrabnezhad et al. / Materials Letters 61 (2007) 2311–2314
UV–VIS diffuse reflectance spectra
Humidity Detection – Optical Sensor
mordenite zeolite
methylene blue
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WWW.wikipedia.com
QCM (Quartz crystal microbalance )
left: Top electrode, right: back electrode
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M. Osada, I. Sasaki, M. Nishioka, M. Sadakata, T.Okubo, Microporous and Mesoporous Materials 23 (1998) 287–294
Sensing of SO2 , FAU zeolite
When SO2 is adsorbed on FAU, the mass increase reduces QCM frequency
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Micro-Cantilevers: rectangular-shaped bars of Si, less than 1 μm thick. Adsorption results in bending of the cantilever
Cantilever array sensor by Hans Peter Lang1,2*, Martin Hegner1, and Christoph Gerber1
Micro-Cantilevers
Mass Loads as small as ~ 5 ng.
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L.Scandella, G. Binder, T. Mezzacasa, J. Gobrecht, R. Berger, H.P. Lang, Microporous & Mesoporous Materials 21 ( 1998) 403
Outgased Zeolite Sensor
Non-Outgased Zeolite Sensor
Humidity sensor using ZSM-5 single crystals
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Jian Zhang and Junhang Dong, Langmuir 2005, 21, 8609-8612
SEM image of MFI thin films grown on endface ofan optical fiber
Detection of dissolved organics in water
Adsorption alters zeolite index of refraction → altering the optical reflectivity → reducing
reflected signal power.
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Calibration curve of pentanoic acid
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Commercial Ludox (Si source)Aluminum foil, Al2O3 (Al source)NaOH: Sodium hydroxide (Na source)
+ organics (catalysts, need removal)TEA: TriethanolamineTPAOH: Tetrapropylamonium hydroxide
(also TEOS:tetraethyl orthosilicate)
Typical Zeolite Synthesis Precursors
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Hydrothermal SynthesisQ: Put in autoclave 6 days4.17 Na2O/ Al2O3/ 6 TEA/ 1.87 SiO2/ 460 H2O
T=85 oC(S. Qiu, et al. Microporous Mesoporous Mater., 21, (1998)
245-251)
Create Nucleation site: Dip substrate in solution with FAU crystals (older solution or commercial batch)
Remove organics: Heat treat composite at 300 oC for 12 hrs
Metglas surface before
synthesis
Metglas’ cross section surface after synthesis
Typical Synthesis on Metglas strip
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Magnetoelastic Sensors
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b)Forced MagnetostrictionMagneto-Elastic ribbons Metglas
Magneto-Elastic materials: Alter their shape under magnetic field H
a) Spontaneous Magnetostriction
Un-magnetized Magnetized-up
H=0
H≠0
H>>0
Length increase
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An alternating magnetic field induces vibrations in the sensor
Magneto-Elastic ribbons
A pick up coil detects magnetic flux changes → generates AC voltage
Elastic modulus density
Frequency
EMF V0
0 /f E
The amplitude V0 peaks when excitation frequency equals resonance frequency f0
V = V0 sin(ωt)
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[1]Grimes CA, Mungle CS, Zeng ZF, et al., Sensors 2 (7): 294-313 JUL 2002
•Change on the mass molecules adsorbed in the zeolite’s crystal reflects to changes on the sensor’s resonance frequency
mE
LE
Lf
21
21
0
The resonance frequency depends on mass m and elastic (Young) modulus
a) Mass loads decrease frequencyb) E is constant in most solid materials but in magnetoelastic
materials it depends on constant (biasing) fields H and stresses σ
H and σ increase or decrease frequency
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0 20 40 60 80 100 120
94,0
94,4
94,8
95,2
95,6
96,0
96,4
96,8N2
CO2
Reso
nanc
e Fr
eque
ncy
[kH
z]
Time [min]
Τ=30οC
Shift in resonance frequency
Cyclic gas changes
ME sensorzeolite
CO2
Frequency (kHz)
EMF
(mV)
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Autoclave
Cut of Metglas ribbon (20 mm x 6mm x 30μm)Metglas cleaning i)CH3CCl3 ii)CH3OH
Deposition of FAU crystals on Metglas strip by dip coating
Heat treat 280 oC 12 hrs to remove organics
FAU sensor
MFI sensor
Sensor fabrication
Zeolite20-30 mm 2826 Metglas 30 m
Zeolite20-30 mm
Hydrothermal syntesis19.5 SiO2 + 438 H20 + organics T=185oCHydrothermal syntesis
4.17 Na2O + Al2O3 + 1.87 SiO2 + 460 H2O + organics
T=85 oC
Ozonication to remove organics at 2000 C
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Zeolite Composition Time(hr)
Tempe-rature
[0C]Ref
FAU 4.17Na2O:1Al2O3:10TEA:1.87SiO2:460H2O 170 85 [1]
LTA 5SiO2:Al2O3:50Na2O:1000H2O 24 60 [2]
MFI 1.5TPAOH :19.5SiO2 :438H2O 24 185 [3]
[1] S. Qiu, J. Yu, G. Zhu, O. Terasaki, Y. Nozue, W. Pang, R. Xu, Microporous and Mesoporous Mater., 21, 245, (1998)[2] G. J. Myatt, P. M. Budd, C. Price, and S. W. Carr, J. Mater. Chem. 2, 1103, (1992)[3] Tuan, V. A.; Li, S. G.; Falconer, J. L.; Noble, R. D, Journal of Membrane Science, 196, 111, (2002)
Synthesis details
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10 15 20 25 30 35
2 theta
IZA
Side B
Side A
10 15 20 25 30
IZA
Side B
2 theta
Side A
FAU
MFI
LTA
10 15 20 25 30
2 theta
IZA
Side B
Side A
020 040 060
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MFI
FAU LTA
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Volatile Organic Compounds
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• Organic liquids with high vapor pressure
• Common by-products in several industrial processes but are also found in everyday life.
• Most of the VOCs vapors are considered harmful and their sensing is a necessity
Volatile Organic Compounds - VOCs
Organic
VOC
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Typical VOC Appearance
Formaldehyde Plywood, pressed and particle board, fiberboard, adhesives, smoke and fumes
Benzene Gasoline fumes, rubber and plastic solvents, smoke, stains, paints, varnishes
Xylenes Adhesives, smoke, solvents, enamels, non-lead auto fuels, wall compounds, caulking, clothes and shoe dyes, wall paper, floor coverings, grease cleaner, varnish, pesticides and kerosene vapors
Toluene Same as Xylenes, plus vinyl floor and wall coverings and calcium silicate sheets
Styrene Paints, synthetic rubber, plastics and resins
Toluene diisocyante (TDI) Paints, synthetic rubber, plastics and resins
Trichlorethylene Polyurethane foam aerosols
Ethyl benzene Solvents
Methylene chloride Aerosol finishers and paint strippers
Paradichlorobenzene Room deodorizers & mothballs
Benzyl chloride & benzal chloride
Vinyl tiles covered with Butyl Benzyl Phthalate
2-Butanone (MEK) Same as Xylenes and Toluene
Petroleum distillates Cleaning, solvent, paint thinner & stripper materials
4-Phenylcyclohexene Synthetic carpet and pads
Some common VOCs
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n-Hexane C6H14Ethyl-acetate C4H8O2
The VOCs of our work
Propylene C3H6 Propane C3H8
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Benzene C6H6
para-Xylene C8H10 ortho-Xylene C8H10
c-Hexane C6H12
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VOC Formula Safe <(ppm) Diameter
Vapor Pressure
[kPa]
Propylene C3H6 - 3.9 Å 1152
Propane C3H8 1000 4.3 Å 970
n-hexane C6H14 20 4.3 Å 20Ethyl-Acetate CH3COOCH2CH3 50 5.2 Å 12.6
p-xylene p-C6H4(CH3)2 100 5.8 Å 1.16
Benzene C6H6 1 5.8 Å 13.4
c-hexane (CH2)6 200 6 Å 13
o-xylene o-C6H4(CH3)2 100 6.8 Å 0.88
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Detection of VOCs with zeolite/ME sensors
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VOC
Experimental Setup
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Experimental Setup
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0 50 100 150 200 250102,50
102,75
103,00
103,25
103,50
AIR
f [
kHz]
Time [min]
ME sensor
Air
ME sensorZeolite film
VOC
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LTAd=4.1 Å
C3H8 (d=4.3 Å)
C3H6 (d=4 Å)
Propylene C3H6 – Propane C3H8, only 4% mass difference, 7% size difference, sensing selectivity problem
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0 50 100 150 200 250
Time [min]
0 50 100 150 200 250
Time [min]0 50 100 150 200
98,098,599,099,5
100,0100,5101,0101,5102,0102,5103,0
Time [min]
f [k
Hz]
AIRC3H8
1200C 800C 400C
Baimpos T, Nikolakis V, Kouzoudis D: Science of Advanced Materials Vol. 2, 215–218, 2010
Air – C3H8
0 100 200 300 40098,098,599,099,5
100,0100,5101,0101,5102,0102,5103,0
Time [min]
f [k
Hz]
0 100 200 300 400 500
Time [min]0 50 100 150 200 250 300 350 400
Time [min]
1200C 800C
400C
Air – C3H6
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0 20 40 60 80 100 120
94,0
94,4
94,8
95,2
95,6
96,0
96,4
96,8N2
CO2
Reso
nanc
e Fr
eque
ncy
[kH
z]
Time [min]
Τ=30οC
Cyclic gas changes
7.4 Å
Size & shape irrelevant, polar interaction Na+ ion - CO2 quadruple moment
Small Parenthesis:CO2 detection, with FAU, Si/Al = 1.1
-- ++++ -- No net charge
2.3 Å
No dipole moment
quadruple moment ≠ 0
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VOC Chemical Formula TLV
(ppm)KineticDiameter
Åo-xylene o-C6H4(CH3)2 100 6.8 c-hexane (CH2)6 200 6 p-xylene p-C6H4(CH3)2 100 5.8 benzene C6H6 1 5.8 ethyl-
acetate CH3COOCH2CH3 50 5.2 n-hexane C6H14 20 4.3
FAU 7.4 Å
MFI 5.5 Å
LTA 4.1 Å
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0 100 200 300 400 500 60095,0
95,5
96,0
96,5
97,0
Time [min]
f [k
Hz]
AIR
620052070
30ppm
o-xylene
FAU ME sensorFAU film
VOC
7.4 Å
0 50 100 150 200 250100,4
100,8
101,2
101,6
102,0
102,4f
[kH
z]
Time [min]
AIR
510ppm 1000
2000
c-hexane
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0 100 200 300 400
105,5
106,0
106,5
107,0
f [k
Hz]
Time [min]
AIR
530ppm
1100 2300
Benzene
0 100 200 300 400 500
95,5
96,0
96,5
97,0
Time [min]
f [k
Hz]
AIR
20001000
500ppm
EthylAcetate
0 100 200 300 400 500 60099,5
100,0
100,5
101,0
101,5
f [k
Hz]Time [min]
AIR
2000 7700
550
400ppm
p-xylene
FAU
0 50 100 150 200 250 30095,5
96,0
96,5
97,0
97,5f
[kH
z]
Time [min]
AIR
1600800ppm
6200
n-hexane
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0 2000 4000 6000 8000
-0,020
-0,015
-0,010
-0,005
0,000
p-xylene
c-hexane
benzeneo-xylene
ethyl-acetate
n-hexane
f/f A
IR
VOC concentration [ppm]
FAU
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para-Xylene C8H10 ortho-Xylene C8H10
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0 100 200 300 400 500
Time [min]
AIR 4100 ppm
1800095000
c-hexane
MFI ME sensorMFI film
VOC
0 100 200 300105,5
106,0
106,5
107,0
107,5
108,0
f [k
Hz]
AIR
2100 ppm 7500
Time [min]
o-xylene
5.5 Å
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UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
0 100 200 300 400105,5
106,0
106,5
107,0
107,5
108,0
f [k
Hz]
Time [min]
AIR
4100 ppm
18000 95000
ethylacetate 0 100 200 300 400
6600028500
4800
Time [min]
AIR
1300 ppm
n-hexane
0 100 200 300 400105,5
106,0
106,5
107,0
107,5
108,0
f [k
Hz]
Time [min]
AIR 4100 ppm
12000 95000
benzene
0 100 200 300 400105,5
106,0
106,5
107,0
107,5
108,0
AIR150 1000
44050 ppm 2300
8200
Time [min]
f [k
Hz]
p-xylene
MFI
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0 25000 50000 75000
-0,012
-0,009
-0,006
-0,003
0,000
0,003
0,006
f/f A
IR
VOC concentration [ppm]
p-xylene
o-xylene
c-hexane
benzene
ethyl-acetate
n-hexane
MFI
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0 100 200 300 400
Time [min]
AIR
1200 ppm 4000 18000 92000
c-hexane
LTA
ME sensorLTA film
VOC
0 100 200 300 400 500 600101,0
101,5
102,0
102,5
103,0
103,5
104,0
f [k
Hz]
Time [min]
AIR
80 ppm 270 1200
6200
o-xylene
4.1 Å
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0 100 200 300 400101,0
101,5
102,0
102,5
103,0
103,5
104,0
85000
f [k
Hz]
Time [min]
AIR
1200 ppm
3900
18000
ethylacetate
0 100 200 300 400 500101,0
101,5
102,0
102,5
103,0
103,5
104,0
f [k
Hz]
AIR
110 ppm
3501600
8200
Time [min]
p-xylene
0 100 200 300 400 500 600
1900 ppm 6200
AIR
28000 142000
Time [min]
n-hexane
LTA
0 100 200 300 400101,0
101,5
102,0
102,5
103,0
103,5
104,0
AIR
1300 ppm
400019000
95000f [k
Hz]
Time [min]
benzene
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0 25000 50000 75000
-0,012
-0,009
-0,006
-0,003
0,000
f/f A
IR
VOC concentration [ppm]
p-xylene
c-hexane
benzene
o-xyleneethyl-acetate
n-hexane
LTA
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UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
VOC FAU MFI LTA
o-xylene 6 * √ - × 90 * ×
c-hexane 150 √ - × - ×
benzene 30 √ - × - ×
p-xylene 20 √ - × 230 ×
ethyl-acetate 15
√ 770
√ -
×
n-hexane 200 √ 190 * √ 700 ×
Numbers: Measured ppm levels by the three sensors. Dashes: no detection Marks √ and × : whether a VOC molecule fits in pore or not.
Results
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0 25000 50000 75000
-0,012
-0,009
-0,006
-0,003
0,000
0,003
0,006
f/f A
IR
VOC concentration [ppm]
p-xylene
o-xylene
c-hexane
benzene
ethyl-acetate
n-hexane
MFIWhy signal reversal? Stress
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UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
(a) (b)
(c)(d)
(e) (f)
air n-hexane
c-hexane benzene
o-xylene p-xylene
MFI one side film
Video
MFI 30 m Metglas 30 m
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Strain
‰Stress (Mpa)
n-hexane 4,4 131
p-xylane 2,4 73
benzene 1,2 37
Stress calculations based on beam theory
MFI 30 m Metglas 30 m
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Slow recovery times - Diffusion
0 100 200 300 400 500 60099,5
100,0
100,5
101,0
101,5
f [k
Hz]
Time [min]
AIR
2000 7700
550
400ppm
p-xylene
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20 40 60 80 10 0 1 20 14 0
100 .2
100 .4
100 .6
100 .8
101 .0
101 .2f
t
Solution a) Thinner zeolite films than 20 m b) Derivative of Response curve.
Theory + data
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0 25000 50000 75000
-0,012
-0,009
-0,006
-0,003
0,000
0,003
0,006
f/f A
IR
VOC concentration [ppm]
p-xylene
o-xylene
c-hexane
benzene
ethyl-acetate
n-hexane
MFI
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MFI 30 m Metglas 30 m
Effects of stress MFI
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MFI 30 m Metglas 30 m
Effects of stress MFI
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UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
Strain
‰Stress (Mpa)
n-hexane 4,4 131
p-xylane 2,4 73
benzene 1,2 37
Stress calculations based on beam theory
MFI 30 m Metglas 30 m
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UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
(a) (b)
(c)(d)
(e) (f)
air n-hexane
c-hexane benzene
o-xylene p-xylene
MFI one side film
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UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
Conclusions
• Zeolite films excellent sensing active layers with nanopores
• High selectively on gas size, shape, polarity
• Room temperature operation• High specific surface • Adsorption stress plays role
• Drawback: Slow recovery time due to diffusion
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http://www.icmmm.net/ 2012.9.21-23 Beijing
UNIVERSITY OF PATRAS FORTH-ICEHTD. Kouzoudis
the 2nd International Conference on Management, Manufacturing and Materials Engineering -ICMMM 2012
Beijing, China Sept. 21-23 2012http://www.icmmm.net/
http://www.icmmm.net/
2012.9.21-23 Beijing