Transcript Slide 1

UNIVERSITY OF PATRAS
D. Kouzoudis
http://www.icmmm.net/
ICMMM2011 , 8-10 Dec
2011, Beijing
Zhengzhou, China
2012.9.21-23
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
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 Letters
University of Patras, Greece
b
FORTH, Patra Greece
ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China
http://www.icmmm.net/
2012.9.21-23 Beijing
UNIVERSITY OF PATRAS
D. Kouzoudis
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Zeolite thin films as new materials for chemically active layers
in magneto-elastic sensors
VOC
Outline
• Zeolite films – excellent active sensing layers Review
Zeolite film
• Magnetoelastic (ME) resonance sensors
ME sensor
• Volatile Organic Compounds (VOC)
• Detection of VOCs with Zeolite/ME sensors
ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China
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Zeolites
(Review on Sensing Applications)
ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China
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Zeolites
• 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
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Zeolites
+
+
Na+
=
• 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 !!!)
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Zeolite Building blocks
FORTH-ICEHT
SiO2 tetrahedra
Chemical formula SiO2?
Tetrahedra connected at corners
Each Oxygen is shared by 2
tetrahedra
All corners are connected
4 × ½ = 2 O atoms →
Si
O Si O
O O
Si
Si
Si
Schematically, oxygen are
shown as straight lines
(bonds) and Si at the
corners
All corners are connected
→ 4 lines from each Si
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Zeolite - Silicalite (MFI)
1-D channels
Si
Si
O
All bonds are homopolar →
no polarity in the crystal →
Extremely hydrophobic
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Zeolite - Silicalite (MFI)
Simplified
planar view
(SiO2)
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Broken
Bond
Two Different
Building blocks
SiO2
AlO2
The Al cannot form heteropolar
bond with one O =>
Local electronegativity =>
Extra cation Na+, Ca++ trapped =>
Polarity in the crystal
Na+
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Zeolite LTA, Si/Al = 1
Simplified
planar view
+
Na
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Na+ [(SiO2) (AlO2)- ]. zH
2O
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Zeolite LTA, Si/Al = 1
+
+
+
Simplified
planar view
+
+
+
+
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Na+ [(SiO2) (AlO2)- ]. zH
2O
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Na
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Zeolite LTA, Si/Al = 1
+
LTA
+
Cations cause polarity → attract
polar molecules (water, CO2)
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Zeolite FAU, Si/Al ≠1
FAU
+
+
+
(Na+, Ca++)
+
Xm+y/m [(SiO2)x (AlO2)-yhttp://www.icmmm.net/
]. zH2O
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LTA
MFI
FAU
D. Kouzoudis
Si 50% - Al 50%
Cations Na, Ca
Polar
3-D straight
channels
Si 100%
non-polar
Hydrophobic
1-D channels
Si x% - Al y%
Cations Na, Ca
Polar
3-D entangled
channels
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Ring 8
Ring 10
Ring 12
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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
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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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Basically there are 5 different ways on how to use
Zeolites for Sensing Applications:
Mass Load
Film Properties
Filter
Guest/Host
Composite
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Mass Load: Selective adsorption of
certain molecules → Microbalance
senses mass load
zeolite
microbalance
QCM, SAW,
Magneto-elastic,
Microcantilever
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Film: Selective adsorption of certain
molecules → Redox interactions with
cations → Change of film property
zeolite
V
Impedance Spectroscopy
Resistive Sensors
Capacitive
Optical
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Filter : Selective adsorption of certain
molecules → make it to the sensitive layer
(+ catalysis )
zeolite
sens. layer
sensor
MOS silicon sensors
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Guest/Host: Certain molecular complexes
pinned at zeolite sites act as sensing centers
such as fluorophores, dyes
complex
Fluorescent
Optical sensors
zeolite
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Composite: Zeolite placed inside a matrix in
order to improve its sensing properties
zeolite
matrix
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Conductive
Polymer sensors
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Type
Mass load
Sensor
QCM
SAW
microcantilever
Sensed Gas
NO, SO2, DMMPS. acetone
pentane, hexane, H2O, NH3
freon
Film
proton conductive
zeolites
Na+ ion conducting
zeolites
Ru(II) complex/zeolite
methylene blue/zeolite
LiCl/zeolites
magnetoelastic
optical fiber
surface plasmon
resonance
NH3
hydrocarbons
methanol, 2-propanol and 3-pentanol
Guest/host
Filter
Composites
polyaniline/zeolite
zirconia/zeolite
platinum/Y-zeolites
SrTi1-xFexO3/zeolite
TiO2/zeolite
SnO2/zeolite
O2, H2O
O2, CO, CO2, organics, butylamine
CO
NO
C4H10, CO and H2
hydrocarbons
alkanes
hydrocarbons
methane, propane, and ethanol
Xiaowen Xu, Jing Wang, and Yingcai Long, Sensors 2006, 6, 1751-1764
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Zeolite based gas sensors
Detection of
Sensor type
Zeolit
e
Detection principle
Freon-12
PZT m-balance
MFI
Adsorption mass load
Acetone
QCM
MFI
Adsorption mass load
Humidity
Water 500 °C
Ammonia
Ohmic
HEU
H MFI
H BEA
Ionic conductivity
Hydrocarbons
Electroch. cell
NaMF
I
Ionic conductivity
Nitric oxide
Electroch. cell
NaFA
U
Catalysis
Pentanoic
acid
Optical fiber
MFI
adsorption induced
reflectivity changes
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Electrical resistance of chromium titanium oxide (CTO) sensors
overlaid with zeolites
Detection ethanol / isopropanol in dry air operated at 4000C
zeolite
ethanol
CTO
isopropanol
V
BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011
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Typically ethanol / isopropanol react with O-- ions, producing CO2
and releasing electrons => Change of resistance
They give similar signal because of same functional group
Bare
Sensor
O--
ethanol
CTO
isopropanol
V
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
zeolite
ethanol
CTO
isopropanol
V
BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011
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+LTA zeolite
Sensor Signal
Bare
Sensor
ethanol
Bare
Sensor
+LTA
isopropanol
Time
BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011
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Hydrocarbon C3H8 Gas Detection – Impedance sensor
The ionic conductivity is measured by
impedance spectroscopy
Z
Gunter Hagen and Ralf Moos, SENSOR
LETTERS 9, 110–113, 2011
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Humidity Detection – Optical Sensor
methylene
blue
mordenite zeolite
UV–VIS diffuse reflectance spectra
change in color upon protonation
/deprotonation of dye molecules
intercalated into the zeolite
http://www.icmmm.net/
S. Sohrabnezhad et al. / Materials Letters
61 (2007)Beijing
2311–2314
2012.9.21-23
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QCM (Quartz crystal microbalance )
left: Top electrode, right: back
electrode
WWW.wikipedia.com
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Sensing of SO2 , FAU zeolite
When SO2 is adsorbed on FAU, the mass increase reduces QCM frequency
M. Osada, I. Sasaki, M. Nishioka, M. Sadakata, T.Okubo,
Microporous and Mesoporous Materials 23 (1998) 287–294
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Micro-Cantilevers
Micro-Cantilevers: rectangularshaped bars of Si, less than 1 μm
thick. Adsorption results in
bending of the cantilever
Mass Loads as small as ~ 5 ng.
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Cantilever array sensor by Hans Peter Lang1,2*, Martin Hegner1, and Christoph Gerber1
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Humidity sensor using ZSM-5 single crystals
Outgased Zeolite Sensor
Non-Outgased Zeolite Sensor
L.Scandella, G. Binder, T. Mezzacasa, J. Gobrecht, R. Berger, H.P. Lang, Microporous & Mesoporous Materials 21 ( 1998) 403
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Detection of dissolved organics in water
Adsorption alters zeolite index of refraction →
altering the optical reflectivity → reducing
reflected signal power.
http://www.icmmm.net/
Jian Zhang and Junhang Dong, Langmuir
2005, 21, 8609-8612
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SEM image of MFI
thin films grown on
endface of
an optical fiber
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Calibration curve of pentanoic
acid
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Typical Zeolite Synthesis Precursors
Commercial Ludox (Si source)
Aluminum foil, Al2O3 (Al source)
NaOH: Sodium hydroxide (Na source)
+ organics (catalysts, need removal)
TEA: Triethanolamine
TPAOH: Tetrapropylamonium hydroxide
(also TEOS:tetraethyl orthosilicate)
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Typical Synthesis on Metglas strip
Create Nucleation site: Dip substrate in solution with
FAU crystals (older solution or commercial batch)
Hydrothermal SynthesisQ: Put in autoclave 6 days
4.17 Na2O/ Al2O3/ 6 TEA/ 1.87 SiO2/ 460 H2O
T=85 oC
(S. Qiu, et al. Microporous Mesoporous Mater., 21, (1998)
245-251)
Remove organics: Heat treat composite at 300 oC
for 12 hrs
Metglas
surface
before
synthesis
Metglas’
cross
section
surface
after
synthesis
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Magnetoelastic Sensors
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Magneto-Elastic materials: Alter their shape under magnetic field H
a) Spontaneous
Magnetostriction
b)Forced Magnetostriction
Magneto-Elastic ribbons Metglas
H=0
Length
increase
Un-magnetized
Magnetized-up
H≠0
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H>>0
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Magneto-Elastic ribbons
An alternating magnetic field
induces vibrations in the sensor
V = V0 sin(ωt)
A pick up coil detects magnetic
flux changes → generates AC
voltage
EMF
V0
Frequency
The amplitude V0 peaks when excitation
frequency equals resonance frequency f0
f0  E / 
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Elastic modulus
density
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The resonance frequency depends on mass m and elastic
(Young) modulus
f0 
1
2L
E


1 E
2L m
a) Mass loads decrease frequency
b) 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
•Change on the mass molecules adsorbed in the zeolite’s crystal reflects to changes
on the sensor’s resonance frequency
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[1]Grimes CA, Mungle CS, Zeng ZF, et al., Sensors 2 (7): 294-313 JUL 2002
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Shift in resonance frequency
CO2
EMF (mV)
zeolite
Frequency (kHz)
Resonance Frequency [kHz]
ME sensor
96,8
N2
96,4
Τ=30οC
96,0
95,6
95,2
94,8
94,4
CO2
94,0
0
20
40
60
80
100
http://www.icmmm.net/ Time [min]
Cyclic gas changes
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120
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Sensor fabrication
Cut of Metglas ribbon (20 mm x 6mm x 30μm)
Metglas cleaning i)CH3CCl3 ii)CH3OH
MFI
sensor
Hydrothermal
syntesis
19.5 SiO2 + 438 H20 +
organics T=185oC
FAU
sensor
Deposition of FAU crystals on
Metglas strip by dip coating
Autoclave
Ozonication to remove
organics at 2000 C
Hydrothermal syntesis
4.17 Na2O + Al2O3 + 1.87
SiO2 + 460 H2O + organics
T=85 oC
Heat treat 280 oC 12 hrs
to remove organics
Zeolite20-30 mm
2826http://www.icmmm.net/
Metglas 30 mm
Zeolite20-30
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Synthesis details
Temperature
[0C]
Ref
Zeolite
Composition
Time
(hr)
FAU
4.17Na2O:1Al2O3:10TEA:1.87SiO2:460
H2O
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)
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LTA
FAU
IZA
Side B
IZA
Side B
Side A
Side A
10
15
20
2 theta
25
10
30
MFI
060
040
020
IZA
Side B
Side A
10
15
2 theta
20
25
http://www.icmmm.net/
302012.9.21-23 Beijing
15
20
2 theta
25
30
35
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FAU
FORTH-ICEHT
LTA
MFI
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Volatile Organic Compounds
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Volatile Organic Compounds - VOCs
• 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
VOC
Organic
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Some common VOCs
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
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The VOCs of our work
Propylene C3H6
Ethyl-acetate
C4H8O2
Propane C3H8
n-Hexane C6H14
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c-Hexane C6H12
Benzene C6H6
para-Xylene C8H10
ortho-Xylene
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C8H10
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Diameter
Vapor
Pressure
[kPa]
VOC
Formula
Safe <
(ppm)
Propylene
C3H6
-
3.9 Å
1152
Propane
C3H8
1000
4.3 Å
970
n-hexane
C6H14
20
4.3 Å
20
Ethyl-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
6Å
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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Experimental Setup
VOC
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Experimental Setup
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Air
VOC
Zeolite film
103,50
ME sensor
[kHz]
103,25
AIR
f
103,00
102,75
102,50
FORTH-ICEHT
0
50
100
150
200
250
Time [min]
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ME sensor
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Propylene C3H6 – Propane C3H8, only 4% mass difference, 7% size
difference, sensing selectivity problem
C3H6
(d=4 Å)
LTA
d=4.1 Å
C3H8
(d=4.3 Å)
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f [kHz]
Air – C3H6
103,0
102,5
102,0
101,5
101,0
100,5
100,0
99,5
99,0
98,5
98,0
400C
1200C
0
100
200
300
800C
400
0
100
200
300
400
5000
50 100 150 200 250 300 350 400
Time [min]
Time [min]
Time [min]
f [kHz]
Air – C3H8
103,0
102,5
102,0
101,5
101,0
100,5
100,0
99,5
99,0
98,5
98,0
AIR
C3H8
1200C
0
50
100
150
800C
200
0
50
100
150
400C
200
250 0
50
100
150
Time [min]
Time [min]
http://www.icmmm.net/
2012.9.21-23
Beijing Vol. 2, 215–218, 2010
Baimpos T, Nikolakis V, Kouzoudis D: Science of
Advanced Materials
Time [min]
200
250
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
Small Parenthesis:
CO2 detection, with FAU, Si/Al = 1.1
-- ++++ --
No net charge
7.4 Å
2.3 Å
No dipole moment
Size & shape irrelevant,
polar interaction Na+ ion CO2 quadruple moment
Resonance Frequency [kHz]
quadruple moment ≠ 0
96,8
N2
96,4
Τ=30οC
96,0
95,6
95,2
94,8
94,4
CO2
94,0
0
20
40
60
80
100
http://www.icmmm.net/ Time [min]
Cyclic gas changes
2012.9.21-23 Beijing
120
UNIVERSITY OF PATRAS
D. Kouzoudis
o-xylene
o-C6H4(CH3)2
100
Kinetic
Diameter
Å
6.8
c-hexane
(CH2)6
200
6
p-xylene
p-C6H4(CH3)2
100
5.8
C 6 H6
1
5.8
CH3COOCH2CH3
50
5.2
C6H14
20
4.3
VOC
benzene
ethylacetate
n-hexane
Chemical
Formula
TLV
(ppm)
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
FAU 7.4 Å
MFI 5.5 Å
LTA 4.1 Å
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
VOC
7.4 Å
FAU
ME sensor
102,4
97,0
AIR
AIR
102,0
f [kHz]
96,5
f [kHz]
30
96,0
ppm
70
520
95,5
95,0
FAU film
6200
100
200
300
400
Time [min]
500
ppm
1000
101,2
2000
100,8
o-xylene
0
510
101,6
600
100,4
c-hexane
0
50
100
150
Time [min]
http://www.icmmm.net/
2012.9.21-23 Beijing
200
250
UNIVERSITY OF PATRAS
FORTH-ICEHT
AIR
Benzene
107,0
D. Kouzoudis
101,5
106,5 AIR
FAU
f [kHz]
f [kHz]
101,0
100,5
106,0
105,5
0
530
ppm
100
400
ppm
100,0
1100
200
300
Time [min]
2300
400
99,5
550
p-xylene
0
100
200
2000
300
400
Time [min]
7700
500 600
97,5
AIR
Ethyl
Acetate
97,0
96,5
AIR
f [kHz]
f [kHz]
97,0
n-hexane
96,5
96,0
800
96,0
95,5 500
ppm
0
100
200
1000
300 400
Time [min]
ppm
1600
6200
2000
95,5
500
0
50
100
150
200
Time [min]
http://www.icmmm.net/
2012.9.21-23 Beijing
250
300
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
FAU
0,000
c-hexane
n-hexane
f/fAIR
-0,005
benzene
-0,010
-0,015
o-xylene
ethyl-acetate
p-xylene
-0,020
0
2000
4000
6000
VOC concentration [ppm]
http://www.icmmm.net/
2012.9.21-23 Beijing
8000
UNIVERSITY OF PATRAS
para-Xylene C8H10
D. Kouzoudis
FORTH-ICEHT
ortho-Xylene C8H10
http://www.icmmm.net/
2012.9.21-23 Beijing
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
VOC
MFI
MFI film
ME sensor
5.5 Å
108,0
f [kHz]
107,5
AIR
107,0
2100 ppm
106,5
106,0
AIR 4100
7500
95000
18000
ppm
o-xylene
c-hexane
105,5
0
100Time
200
[min]
300
0
100
200
300
Time [min]
http://www.icmmm.net/
2012.9.21-23 Beijing
400
500
D. Kouzoudis
108,0
108,0
107,5
107,5 AIR
107,0
AIR
106,5
4100
ppm
12000
95000
benzene
f [kHz]
f [kHz]
UNIVERSITY OF PATRAS
8200
105,5
105,5
200
300
400
2300
106,5
106,0
100
1000
50 440
ppm
107,0
106,0
0
150
FORTH-ICEHT
Time [min]
p-xylene
0
100
200
300
400
Time [min]
108,0
AIR
AIR
28500
107,5
66000
f [kHz]
107,0
106,5
4100
ppm
18000
1300 ppm
95000
106,0
4800
105,5
ethyl
0
100
200
300
acetate Time [min]
400
0
100
n-hexane
200
http://www.icmmm.net/Time [min]
2012.9.21-23 Beijing
300
400
MFI
UNIVERSITY OF PATRAS
MFI
0,006
n-hexane
0,003
f/fAIR
D. Kouzoudis
o-xylene
0,000
benzene
-0,003
c-hexane
p-xylene
-0,006
-0,009
ethyl-acetate
-0,012
0
25000
50000
75000
VOC concentration [ppm]
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
LTA
VOC
LTA film
ME sensor
4.1 Å
104,0
103,5 AIR
f [kHz]
103,0
AIR
80
ppm 270
102,5
1200
4000
ppm
1200
102,0
18000
92000
6200
101,5
c-hexane
o-xylene
101,0
0
100
200
300
400
Time [min]
500
600
0
100
200
300
Time [min]
http://www.icmmm.net/
2012.9.21-23 Beijing
400
D. Kouzoudis
104,0
104,0
103,5 AIR
103,5
103,0
1300 4000
ppm
102,5
19000
102,0
95000
101,5
101,0
f [kHz]
f [kHz]
UNIVERSITY OF PATRAS
0
100
200
300
400
Time [min]
AIR
103,0
110 350
ppm
102,5
1600
LTA
8200
102,0
101,5
benzene
FORTH-ICEHT
101,0
p-xylene
0
100
200
300
400
500
Time [min]
104,0
AIR
f [kHz]
103,5 AIR
103,0
1200
ppm
102,5
142000
28000
18000
102,0
ethyl
acetate
101,5
101,0
1900
6200
ppm
3900
0
100
85000
200
300
Time [min]
400
n-hexane
0
100
200
300
400
Time [min]
http://www.icmmm.net/
2012.9.21-23 Beijing
500
600
UNIVERSITY OF PATRAS
D. Kouzoudis
LTA
0,000
-0,003
f/fAIR
c-hexane
n-hexane
-0,006
benzene
p-xylene
-0,009
o-xylene
-0,012
0
25000
ethyl-acetate
50000
75000
VOC concentration [ppm]
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
Results
Numbers: Measured ppm levels by the three sensors.
Dashes: no detection
Marks √ and × : whether a VOC molecule fits in pore or not.
VOC
oxylene
chexane
benzene
pxylene
ethylacetate
nhexane
FAU
6
*
150
30
20
MFI
√
√
√
√
LTA
×
-
×
-
×
-
×
-
√
15
200
*
230
√
770
√
90
190
×
×
×
×
×
*
http://www.icmmm.net/
2012.9.21-23 Beijing
√
700
×
UNIVERSITY OF PATRAS
FORTH-ICEHT
Why signal
reversal? Stress
MFI
0,006
n-hexane
0,003
f/fAIR
D. Kouzoudis
o-xylene
0,000
benzene
-0,003
c-hexane
p-xylene
-0,006
-0,009
ethyl-acetate
-0,012
0
25000
50000
75000
VOC concentration [ppm]
http://www.icmmm.net/
2012.9.21-23 Beijing
UNIVERSITY OF PATRAS
D. Kouzoudis
MFI one side film
(a)
air
Metglas 30 mm
MFI 30 mm
(b)
n-hexane
(d)
(c)
benzene
c-hexane
(f)
(e)
o-xylene
FORTH-ICEHT
p-xylene
http://www.icmmm.net/
2012.9.21-23 Beijing
Video
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
Stress calculations based on beam theory
Metglas 30 mm
MFI 30 mm
Strain
Stress
n-hexane
4,4
131
p-xylane
2,4
73
benzene
1,2
37
e‰
http://www.icmmm.net/
2012.9.21-23 Beijing
s (Mpa)
UNIVERSITY OF PATRAS
D. Kouzoudis
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
Slow recovery times - Diffusion
AIR
p-xylene
101,5
f [kHz]
101,0
100,5
400
ppm
100,0
99,5
http://www.icmmm.net/
2012.9.21-23 Beijing
550
2000
0
100
200
300
400
Time [min]
7700
500 600
UNIVERSITY OF PATRAS
f
D. Kouzoudis
FORTH-ICEHT
101.2
101.0
Theory + data
100.8
100.6
100.4
100.2
20
40
60
80
100
120
140
t
Solution a) Thinner zeolite films than 20 mm
b) Derivative of Response curve.
http://www.icmmm.net/
2012.9.21-23 Beijing
UNIVERSITY OF PATRAS
MFI
0,006
n-hexane
0,003
f/fAIR
D. Kouzoudis
o-xylene
0,000
benzene
-0,003
c-hexane
p-xylene
-0,006
-0,009
ethyl-acetate
-0,012
0
25000
50000
75000
VOC concentration [ppm]
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
Effects of stress MFI
Metglas 30 mm
MFI 30 mm
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
Effects of stress MFI
Metglas 30 mm
MFI 30 mm
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
Stress calculations based on beam theory
Metglas 30 mm
MFI 30 mm
Strain
Stress
n-hexane
4,4
131
p-xylane
2,4
73
benzene
1,2
37
e‰
http://www.icmmm.net/
2012.9.21-23 Beijing
s (Mpa)
UNIVERSITY OF PATRAS
D. Kouzoudis
MFI one side film
(a)
air
(b)
n-hexane
(d)
(c)
benzene
c-hexane
(f)
(e)
o-xylene
p-xylene
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. 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
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
http://www.icmmm.net/
2012.9.21-23 Beijing
FORTH-ICEHT
UNIVERSITY OF PATRAS
D. Kouzoudis
FORTH-ICEHT
nd
2
the
International Conference
on Management, Manufacturing
and Materials Engineering ICMMM 2012
Beijing, China Sept. 21-23 2012
http://www.icmmm.net/
http://www.icmmm.net/
2012.9.21-23 Beijing