Dimethyl ether (DME) is found to be an alternative diesel fuel because of: low NO emission ...

Laboratory preparation of modified ZSM- 5 nano catalyst

with aluminophosphate (AlPO) for methanol to Dimethyl Ether

reaction

BY:YADOLLAH TAVAN

SUPERVISORS:Dr. A. Shariati

Dr. M.R. Khosravi Nikou

OCTOBER 2011

3

Petroleum University of Technology

MTD process and their Catalysts

Catalyst Synthesize

Catalyst Characterization

Results

Conclusion

Contents

4


Dimethyl ether (DME) is found to be an alternative diesel fuel because of:

low NO emission near-zero smoke amounts less engine noise

and replace chlorofluorocarbons (CFCs) used as an aerosol propellant

• At present DME is commercially produced by the dehydration of methanol

Importance of DME

5


• The general reaction path of the methanol conversion:

First methanol dehydration to dimethylether (DME).

Then converted to light olefins.

MTD process and its Catalysts

6


The reaction takes place on:

different solid–acid catalysts such as γ-alumina H-ZSM-5

o temperature range of 250–400 °С

o pressures up to 18 bar

MTD process and its Catalysts

7


HZSM-5: Interesting feature:

Drawback Hydrocarbons formation at 270 C

MTP process and its Catalysts

Higher Catalytic activity

Higher Stability

Higher Performance

Existence of strong acid-sites

8


Generally adopted methods for acidity modification of ZSM-5 are:

Exchange of protons with Na ions

Modification with P containing compounds and Promoters

o Using Binder materials

Other modifications

Catalyst Modification

9


• Chemicals

Aluminium nitrate nano-hydrate [ANN; Al (NO3)3.9H2 O, extra pure, Merck]

Ortho-phosphoric acid [H3PO4, 85wt%, analysis grade, Merck]

o HZSM-5(SiO2 /Al2O3=67.6, ZEOCHEM, Switzerland)

Synthesize

10

Petroleum University of TechnologyCatalyst Preparation Steps

ANN Dilution

Homogenization

Phosphoric Acid addition

HZSM-5 Addition

Filtration and Washing

Drying

Synthesize

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Characterization

Catalyst characterization

XRD

BET

NH3-TPD

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Vertical fixed bed micro-reactor 316 stainless steel tubing I.D = 0.75 inch length=19 cm Nearby atmospheric pressure. Methanol (Grade AA, 99.9% purity, Fanavaran petrochemical)

was supplied by the HPLC pump, vaporized through the heater and fed to the reactor.

The reaction temperature from 155 to 460°C. All the experiments were performed with 3gr of catalysts. Weight Hourly Space Velocity (WHSV) of 15 to 90 grams of

methanol per grams of catalyst per hour (g g-1h-1) by changing methanol rate

Product analysis was performed using gas chromatography (Young Lin, ACME 6100).

Experimental

13


Results

14


Scherrer Equation:

HZSM-5: B=0.0218 (1.25°*π/180) maximum peak was occurred in 23.235° the crystal size derived by Scherrer equation is 10.79 nm

Synthesized Catalysts: crystal sizes were 13-15nm for synthesized catalysts and are

well nano sized.

Results

Bθ

KλD=

Bcos

15


Results

CatalystSpecific surface

area (m2/gr)

HZSM-5 401.52

ZALPO(P/Al=0.3) , A 401.02

ZALPO(P/Al=0.8), B 398.80

ZALPO(P/Al=1.2), C 387.90

ZALPO(P/Al=1.5), D 382.50

The HZSM-5 exhibits higher surface area. By addition of phosphorus to the binder, the surface area

decreased Attributed to the formation of AlPO

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The nature of N2 adsorption-desorption isotherms

Type IV curve using IUPAC classification for hysteresis loops

The predominance of mesopores for HZSM-5 Mesopores: pore diameter=2-50nm due to capillary

condensation taking place in mesopores. Hysteresis loops may exhibit a wide variety of shapes. In present work pore shape might be ink-bottle form.

Results

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Pore diameter was varied from 18 to 963nm for HZSM-5.

the prominent distribution was observed at range of 25-47nm mainly includes mesopore size.

Well-developed mesopore structure of the catalyst would help mass and heat transfer easy in reaction.

Results

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Results

Catalyst, Sample

name

Low

temperature

(C)

Quantity at low

temperature

(mmol/gr NH3)

High

temperature

(C)

Quantity at

high

temperature

(mmol/gr

NH3)

Total quantity

(mmol/gr NH3)

HZSM-5 196 0.673 398 0.492 1.165

ZAlPO(P/Al=0.3), A 184 0.519 397 0.413 0.932

ZAlPO(P/Al=0.8), B 184 0.523 393 0.473 0.996

ZAlPO(P/Al=1.2), C 179 0.473 364 0.27 0.743

ZAlPO(P/Al=1.5), D 176 0.453 360 0.263 0.716

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A B

C D

Results

The ammonia TPD plots of the calcined sampleso low temperature peak around 190°C high temperature peak around 390°C.

The former from the weakly acidic that cover the external surface of the catalysts.

The latter peak arises from the Bronsted acid sites

o The intensity of high temperature peak decreases with the increase of phosphorous

o Effective interaction of phosphorous with the binder and zeolite framework.

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Results The effect of Temperature on HZSM-5:

21


Results

The effect of WHSV: The influence of WHSV within wide range of 15-90 gr/

(hr.gr-cat) was investigated

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Design of Experiments (DOE):

Results.

Control Factors Levels

1 2 3

Temperature(C) 212 230 252

WHSV 15 30 60

L9 orthogonal array

Optimum Temperature was 252 C

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Results

30 35 40 45 50 55 60 650.700000000000001

0.720000000000001

0.740000000000001

0.760000000000001

0.780000000000001

0.800000000000001

0.820000000000001

0.840000000000001

0.860000000000001

0.880000000000001

HZSM-5ZALPO(P/Al=0.3)ZALPO(P/Al=0.8)ZALPO(P/Al=1.2)ZALPO(P/Al=1.5)

WHSV(1/hr)

Met

hano

l Con

vers

ion

0 0.2 0.4 0.6 0.8 1 1.2 1.40.670000000000005

0.720000000000005

0.770000000000005

0.820000000000005

0.870000000000005

0.920000000000005

WHSV=30

WHSV=45

WHSV=60

P/Al molar ratio

Met

hano

l Con

vers

ion

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In the present research: Synthesized catalysts showed better conversion than

HZSM-5.

It was found that P/Al molar ratio of 0.8 has better conversion than other.

For optimum catalyst, reactor temperature was raised to 315°C and no comparable by-product was detected in GC spectra.

Conclusion

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I would like to thank Dr. Ahmad Shariati and Dr. Mohammad Reza Khosravi Nikou, for their supervision throughout my research project.

I would like to thank ZEOCHEM,AG company for supplying zeolites.

I would like to thank Abadan Refinery Company and Iranian nanotechnology initiative council for their financial support of my thesis.

Finally, I would like to thank lab mates.

Acknowledgments:

Thanks for Your Attention

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Dimethyl ether (DME) is found to be an alternative diesel fuel because of: low NO emission ...

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