Petroleum University of Technology Gas Engineering Department 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

Contents MTD process and their Catalysts Catalyst Characterization Catalyst Synthesize Catalyst Characterization Results Conclusion

Importance of DME 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

MTD process and its Catalysts The general reaction path of the methanol conversion: First methanol dehydration to dimethylether (DME). Then converted to light olefins.

MTD process and its Catalysts The reaction takes place on: different solid–acid catalysts such as γ-alumina H-ZSM-5 temperature range of 250–400 °С pressures up to 18 bar

Higher Catalytic activity Existence of strong acid-sites MTP process and its Catalysts HZSM-5: Interesting feature: Drawback Hydrocarbons formation at 270 C Higher Catalytic activity Higher Stability Higher Performance Existence of strong acid-sites

Catalyst Modification Generally adopted methods for acidity modification of ZSM-5 are: Exchange of protons with Na ions Modification with P containing compounds and Promoters Using Binder materials Other modifications

Synthesize Chemicals Aluminium nitrate nano-hydrate [ANN; Al (NO3)3.9H2 O, extra pure, Merck] Ortho-phosphoric acid [H3PO4, 85wt%, analysis grade, Merck] HZSM-5(SiO2 /Al2O3=67.6, ZEOCHEM, Switzerland)

Catalyst Preparation Steps Synthesize Catalyst Preparation Steps ANN Dilution Homogenization Phosphoric Acid addition HZSM-5 Addition Filtration and Washing Drying

Catalyst characterization XRD BET NH3-TPD

Experimental 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).

Results

Results 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.

Specific surface area (m2/gr) Results Catalyst Specific 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

Results 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 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.

Quantity at low temperature Quantity at high temperature Results Catalyst, Sample name Low temperature (C) Quantity at low temperature (mmol/gr NH3) High temperature Quantity at high temperature (mmol/gr NH3) Total quantity 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 0.523 393 0.473 0.996 ZAlPO(P/Al=1.2), C 179 364 0.27 0.743 ZAlPO(P/Al=1.5), D 176 0.453 360 0.263 0.716

Results The ammonia TPD plots of the calcined samples B C D The ammonia TPD plots of the calcined samples 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 The intensity of high temperature peak decreases with the increase of phosphorous Effective interaction of phosphorous with the binder and zeolite framework.

Results The effect of Temperature on HZSM-5:

Results The effect of WHSV: The influence of WHSV within wide range of 15-90 gr/ (hr.gr-cat) was investigated

Results Design of Experiments (DOE): L9 orthogonal array . Design of Experiments (DOE): Control Factors Levels 1 2 3 Temperature(C) 212 230 252 WHSV 15 30 60 L9 orthogonal array Optimum Temperature was 252 C

Results

Conclusion 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.

Acknowledgments: 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.

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