Selective Detection of Dialkyl Phthalate by Molecular-sieving Sensor Selective Detection of Dialkyl Phthalate by Molecular-sieving Sensor Naonobu KatadaNaonobu Katada, Ken-ichi Fukuchi, Hideyuki Iwata, and Miki Niwa, Ken-ichi Fukuchi, Hideyuki Iwata, and Miki Niwa

Tottori Univ., Fuji Electric Systems Co. Ltd.Tottori Univ., Fuji Electric Systems Co. Ltd.

Selective deetction

Toluene

SnO2

35 cm35 cm

14 cm14 cm

40 cm40 cm

DAPDAP (dialkyl phthalate) = plasticizer (dialkyl phthalate) = plasticizerSeveral Several g mg m-3-3 of DAP gives damage for device on semiconductor surface of DAP gives damage for device on semiconductor surface

Practical method for analysis of DAPPractical method for analysis of DAP in g mg m-3-3 scale

DOP (Dioctyl phthalate)

DEHP (Bis-2-ethylhexylphthalate)

Selective Detection of Dialkyl Phthalate by Molecular-sieving Sensor Selective Detection of Dialkyl Phthalate by Molecular-sieving Sensor Naonobu KatadaNaonobu Katada, Ken-ichi Fukuchi, Hideyuki Iwata, and Miki Niwa, Ken-ichi Fukuchi, Hideyuki Iwata, and Miki Niwa

Tottori Univ., Fuji Electric Systems Co. Ltd.Tottori Univ., Fuji Electric Systems Co. Ltd.

DBP (Dibutyl phthalate)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

SnSn4+4+

SnOSnO22 semiconductor gas sensor semiconductor gas sensor

OO2-2- SnSn4+4+ OO2-2- SnSn2+2+ OO2-2- SnSn4+4+ OO2-2-

SnSn4+4+ OO2-2- SnSn4+4+ OO2-2- SnSn4+4+ OO2-2- SnSn4+4+ OO2-2-

SnSn4+4+ OO2-2- SnSn4+4+ OO2-2- SnSn4+4+ OO2-2- SnSn4+4+ OO2-2-

OO2-2- OO2-2- OO2-2- OO2-2-

OO2-2- OO2-2- OO2-2- OO2-2-

OO2-2- OO2-2-

SnSn4+4+ OO2-2- SnSn4+4+ OO2-2-

SnSn4+4+ OO2-2- SnSn4+4+ OO2-2-

SnSn4+4+ OO2-2- SnSn4+4+ OO2-2-

OO2-2- OO2-2-

OO2-2- OO2-2-

OO2-2- OO2-2-

OO2-2- OO2-2- OO2-2- OO2-2- OO2-2- OO2-2-

[ ][ ] OO2-2-

CHCH44

COCO22HH22OO

OO2-2-

Electrical response to flammable compoundElectrical response to flammable compoundReactive for any of organic compoundReactive for any of organic compound

ee-- → →

There are other gases [toluene, isopropaThere are other gases [toluene, isopropanol (IPA) and methylethyl ketone (MEK)] nol (IPA) and methylethyl ketone (MEK)] even in clean rooms.even in clean rooms.

SelectiveSelective detection is needed. detection is needed.

SnOSnO22

OO -

Si(OCH3)4Molecular sieving propertyMolecular sieving property

++

SnOSnO22’s’s

Sensing FunctionSensing Function

OO22

CHO

SiOSiO22 layer layer

COCO22, H, H22OO

CVD of SiOCVD of SiO22 in the presence of molecular template in the presence of molecular template

on SnOon SnO22 surface surface J. Chem. Soc., Chem. Commun.,J. Chem. Soc., Chem. Commun., 1995,1995, 623. 623.

Shape-selective adsorptionShape-selective adsorption Bull. Chem. Soc. Jpn.,Bull. Chem. Soc. Jpn., 78,78, 1425 (2005). 1425 (2005).

Application to molecular-sieving sensorApplication to molecular-sieving sensor Sens. Actuators, B: Chem., 124, 398 (2007)

SnOSnO22

SiOSiO22

catalytic oxidationcatalytic oxidation

Electric responseElectric response

MolecularMolecular--sieving Sensorsieving Sensor

Aim of this studyAim of this study

Application of molecular-sieving sensor to detection of DAP Application of molecular-sieving sensor to detection of DAP in the co-presence of toluene, IPA and MEKin the co-presence of toluene, IPA and MEK

1. Selective detection1. Selective detection

2. Detection in 2. Detection in g mg m-3-3 scale scale

3. Prototype analyzer3. Prototype analyzer

ExperimentalExperimental

Pd/SnO2 powder, 20 m2 g-1

Pt wire

OO OO

SnO2

OO

100 nm

5 mm5 mm

He

SampleSampleElectric furnaceElectric furnace

・ 1-Naphthaldehyde (template) was injected at 343 K・ Si(OCH3)4 vapor was fed at 473 K・ O2 was fed at 673 K

[Sens. Actuators, B: Chem., 124, 398 (2007)]

PreparationPreparation

Air (100 cm3 min-1)

Electric resistanceElectric resistance

0.5 mm0.5 mm33 liquid liquid

673 K673 K

Sensor measurementsSensor measurements

DOP / Toluene / AirDOP / Toluene / Air

Very low concentration of DOP / AirVery low concentration of DOP / Air1. Purification of DOP vapor was carried out;1. Purification of DOP vapor was carried out;

DOP liquid was heated at 383 K for 10 h in He flow.DOP liquid was heated at 383 K for 10 h in He flow.He was further flowed at room temperature for 24 h.He was further flowed at room temperature for 24 h.DOP vapor was trapped to confirm the purity.DOP vapor was trapped to confirm the purity.

2. Thus prepared 4.8 mg m2. Thus prepared 4.8 mg m-3-3 DOP / air was diluted with pure air. DOP / air was diluted with pure air.3. Equipment was heated and completely purged before the measurements.3. Equipment was heated and completely purged before the measurements.

-200 0 200 400 6000

10

20

30

40

t / s

Ra/

R-1

-200 0 200 400 6000

10

20

30

40

t / sR

a/R

-1

DOP

DBP

DEHP

Toluene

IPA

MEK

All compounds detectedAll compounds detected

Results and DiscussionResults and Discussion

0.5 mm3 (as liquid) of

Pd/SnOPd/SnO22 (unmodified) sensor (unmodified) sensor

-200 0 200 400 6000

10

20

30

40

Ra/

R-1

t / s-200 0 200 400 600

0

10

20

30

40

Ra/

R-1

t / s

DOP

DBP

DEHP

Toluene

IPA

MEK

DOP, DEHP, DBP --- selectively detectedDOP, DEHP, DBP --- selectively detected

Toluene, MEK, IPA --- not detected Toluene, MEK, IPA --- not detected

SiOSiO22/Pd/SnO/Pd/SnO22 prepared using 1-NA template (molecular-sieving) sensor prepared using 1-NA template (molecular-sieving) sensor

Why?Why?

Detected by molecular-sieving sensorDetected by molecular-sieving sensorDOPDOP, , DEHPDEHP, , DBPDBP, linear alkane, ethanol, linear alkane, ethanol

UndetectedUndetectedTolueneToluene, , IPAIPA, , MEKMEK, benzene, branched alkane, dimethyl phth, benzene, branched alkane, dimethyl phthalate (DMP)alate (DMP)

Detection of Detection of g mg m-3-3 of DOP of DOP

Response of Pd/SnOResponse of Pd/SnO22 to steady flow of DOP/air to steady flow of DOP/air

-600 0 600 1200 1800

0

0.5

1

t / s

Ra/

R-1

0

1680

160320

480

1600 g m-3

800

640

Detection limit = 500 Detection limit = 500 Target = Target = g mg m-3-3

But the target is not far!But the target is not far!

Concentration of DOP using an Concentration of DOP using an adsorbent column is attempted.adsorbent column is attempted.

vent

sample

adsorbent trap (porous polymer beads)

furnace

sensor

6-way valve

O2

N2

flush by heating

300 cm3 min-1×100 min

0 500 10000

1

2

3

4

5

t / s

Ra/

R-1

8.0 g m-3

4.8 g m-3

Response by Pd/SnO2

Air + DOP Air + Toluene (110 mg m-3)

0 500 10000

1

2

3

4

5

t / s

CDOP = 0 ppb

Ra/

R-1

(toluene only)

5 - 8 5 - 8 g mg m-3-3 DOP was detected. DOP was detected.

0 500 1000-0.1

0

0.1

0.2

0.3

0.4

t / s

Ra/

R-1

CDOP = 0

8.0 g m-3

4.8 mg m-3

Selective response by SiOSelective response by SiO22/Pd/SnO/Pd/SnO22

Air + DOP

4.8 g m-3

8.0 g m-3

0 500 1000-0.1

0

0.1

0.2

0.3

0.4

t / s

CDOP = 0

Ra/R

- 1

Air + Tol. (110 mg m-3)

DOP (5 - 8 DOP (5 - 8 g mg m-3-3), detected), detectedToluene (110,000 Toluene (110,000 g mg m-3-3), not affecting), not affecting

Selective detection of pollutant at a low concentrationSelective detection of pollutant at a low concentration

+ DOP

vent

sample

adsorbent trap (porous polymer beads)

furnace

sensor

6-way valve

O2

N2

flush by heating

300 cm3 min-1×100 min

Complex valvesComplex valvesNN22 and O and O22 supply supply

vent

sample (250 cm3 min-1×40 min)

adsorbent trap(MCM-41, mesoporous silica)

furnace

sensor

Simple systemSimple system

313 313 ～ ～ 423 K ←→ 673 K423 K ←→ 673 K

35 cm35 cm

14 cm14 cm

40 cm40 cm

Prototype analyzerPrototype analyzer

Adsorbent columnAdsorbent column

Electric furnaceElectric furnace

SensorsSensors

PumpPump

Electric Electric testertester

Temperature Temperature controllerscontrollers

Sample airSample air

A signal (noise) was A signal (noise) was observed by heating observed by heating adsorbent.adsorbent.

5 - 8 5 - 8 g mg m-3-3 is safely detected in any case. is safely detected in any case.

-200 0 200 400 600

0

0.5

1

1.5

Ra/

R-1

t / s

120 g m-3

CDOP = 0

2.4 g m-3

4.8 g m-3

24 g m-3

Collected Collected for 40 minfor 40 min-1-1

Response by Pd/SnO2

Air + DOP

-200 0 200 400 600

0

0.5

1

1.5

Ra/

R-1

t / s

120 g m-3

CDOP = 0

2.4 g m-3

4.8 g m-3

24 g m-3

Collected Collected for 40 minfor 40 min-1-1

Response by Pd/SnO2

Air + DOP

-200 0 200 400 600-1

0

1

2

t / sR

0/R

-1

Pd/SnO2

02.4 g m-3

4.8 g m-3

Air + Toluene (110 mg m-3) + DOP

Unmodified sensorUnmodified sensor

Continuous flow of tolueneContinuous flow of toluene--> Complex change--> Complex change

Signal by DOP hiddenSignal by DOP hidden

Air + Toluene (110 mg mAir + Toluene (110 mg m-3-3) + DOP) + DOP

Unmodified sensorUnmodified sensor

Continuous flow of tolueneContinuous flow of toluene--> Complex change--> Complex change

Signal by DOP hiddenSignal by DOP hidden

-200 0 200 400 600-1

0

1

2

t / s

R0/

R-1

1-NA SiO 2/Pd/SnO2

02.4 g m-3

4.8 g m-3

-200 0 200 400 600-1

0

1

2

t / s

R0/

R-1

Pd/SnO2

02.4 g m-3

4.8 g m-3

Molecular-sieving sensorMolecular-sieving sensor

Response to tolueneResponse to toluene--> Suppressed--> Suppressed

3 - 5 3 - 5 g mg m-3-3 of DOP detected of DOP detected

Collected for 40 minCollected for 40 min-1-1

These are tentative results; final tests are now proceeding.These are tentative results; final tests are now proceeding.

ConclusionsConclusions

1. The molecular-sieving sensor (SiO1. The molecular-sieving sensor (SiO22/Pd/SnO/Pd/SnO22) detected) detected

○ ○ DOP, DEHP, DBP (ethanol, linear alkane)DOP, DEHP, DBP (ethanol, linear alkane)× Toluene, IPA, MEK (DMP, branched alkane)× Toluene, IPA, MEK (DMP, branched alkane)

2. About 5 2. About 5 g mg m-3-3 of DOP could be detected when a suitable of DOP could be detected when a suitable adsorption - desorption system was combined. adsorption - desorption system was combined.

3. 5 3. 5 g mg m-3-3 of DOP was detected within 50 min in the co- of DOP was detected within 50 min in the co-presence of 110 mg mpresence of 110 mg m-3-3 of toluene by a prototype analyzer. of toluene by a prototype analyzer.

Thank you for your kind attention!Thank you for your kind attention!