Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction

Olefins are one of the most important chemicals and raw materials in the petrochemical industry. However, because of the rapid increase in the price of crude oil and the oil shortage in the foreseeable future, alternative routes for production of light olefins from non-oil sources are desired. Catal...

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Main Author:	Jamian, Siti Fatimah
Format:	Thesis
Language:	English
Published:	2018
Subjects:	Q Science (General)
Online Access:	http://eprints.utm.my/id/eprint/81417/1/SitiFatimahJamianMFS2018.pdf
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spelling	my-utm-ep.814172019-08-23T04:07:15Z Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction 2018 Jamian, Siti Fatimah Q Science (General) Olefins are one of the most important chemicals and raw materials in the petrochemical industry. However, because of the rapid increase in the price of crude oil and the oil shortage in the foreseeable future, alternative routes for production of light olefins from non-oil sources are desired. Catalytic conversion of methanol to light olefins (MTO) provides an alternative route for production of light olefins from a non- petroleum source. Protonated commercial ZSM-5 (HZSM-5) zeolite has been widely used in the MTO reaction. However, fast deactivation of HZSM-5 due to coke deposition has always been one of the key problems in MTO reaction. A novel ZSM- 5 catalyst with silica fibrous morphology (HSi@ZSM-5) was successfully prepared using a microemulsion system with ZSM-5 seed assisted crystallization followed by protonation for MTO reaction. X-ray diffraction and field emission scanning electron microscopy analyses showed that the HSi@ZSM-5 possesses ZSM-5 structure and a spherical morphology with evenly distributed dendrimeric silica fibers. In addition, HSi@ZSM-5 exhibited intrinsic mesopores at 3-5 and 10-20 nm, which led to an increase in the surface area up to 22% compared with HZSM-5. Ammonia Fourier transform infrared spectroscopy result showed a remarkable reduction of Brønsted acid sites in HSi@ZSM-5. This reduction of Brønsted acid sites suppressed side reactions which led to increased olefin selectivity. These were proven in the catalytic activity as the propylene selectivity of HSi@ZSM-5 was almost two-fold higher than that of HZSM-5. Besides, the catalytic lifetime was improved significantly up to 80 hours for HSi@ZSM-5 compared to about 30 hours for HZSM-5. The high selectivity towards propylene and long catalyst lifetime of HSi@ZSM-5 could be attributed to the unique morphology of HSi@ZSM-5 which facilitates the diffusion of reactant and product into and out of the catalyst. Lowering diffusion limitation reduces the possibility of coke accumulation on the catalyst that lead to the deactivation of the catalyst. This new protonated silica fibrous ZSM-5 catalyst opens a big potential in general heterogeneous catalytic reaction. 2018 Thesis http://eprints.utm.my/id/eprint/81417/ http://eprints.utm.my/id/eprint/81417/1/SitiFatimahJamianMFS2018.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:125165 masters Universiti Teknologi Malaysia Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	Q Science (General)
spellingShingle	Q Science (General) Jamian, Siti Fatimah Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction
description	Olefins are one of the most important chemicals and raw materials in the petrochemical industry. However, because of the rapid increase in the price of crude oil and the oil shortage in the foreseeable future, alternative routes for production of light olefins from non-oil sources are desired. Catalytic conversion of methanol to light olefins (MTO) provides an alternative route for production of light olefins from a non- petroleum source. Protonated commercial ZSM-5 (HZSM-5) zeolite has been widely used in the MTO reaction. However, fast deactivation of HZSM-5 due to coke deposition has always been one of the key problems in MTO reaction. A novel ZSM- 5 catalyst with silica fibrous morphology (HSi@ZSM-5) was successfully prepared using a microemulsion system with ZSM-5 seed assisted crystallization followed by protonation for MTO reaction. X-ray diffraction and field emission scanning electron microscopy analyses showed that the HSi@ZSM-5 possesses ZSM-5 structure and a spherical morphology with evenly distributed dendrimeric silica fibers. In addition, HSi@ZSM-5 exhibited intrinsic mesopores at 3-5 and 10-20 nm, which led to an increase in the surface area up to 22% compared with HZSM-5. Ammonia Fourier transform infrared spectroscopy result showed a remarkable reduction of Brønsted acid sites in HSi@ZSM-5. This reduction of Brønsted acid sites suppressed side reactions which led to increased olefin selectivity. These were proven in the catalytic activity as the propylene selectivity of HSi@ZSM-5 was almost two-fold higher than that of HZSM-5. Besides, the catalytic lifetime was improved significantly up to 80 hours for HSi@ZSM-5 compared to about 30 hours for HZSM-5. The high selectivity towards propylene and long catalyst lifetime of HSi@ZSM-5 could be attributed to the unique morphology of HSi@ZSM-5 which facilitates the diffusion of reactant and product into and out of the catalyst. Lowering diffusion limitation reduces the possibility of coke accumulation on the catalyst that lead to the deactivation of the catalyst. This new protonated silica fibrous ZSM-5 catalyst opens a big potential in general heterogeneous catalytic reaction.
format	Thesis
qualification_level	Master's degree
author	Jamian, Siti Fatimah
author_facet	Jamian, Siti Fatimah
author_sort	Jamian, Siti Fatimah
title	Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction
title_short	Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction
title_full	Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction
title_fullStr	Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction
title_full_unstemmed	Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction
title_sort	synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction
granting_institution	Universiti Teknologi Malaysia
granting_department	Science
publishDate	2018
url	http://eprints.utm.my/id/eprint/81417/1/SitiFatimahJamianMFS2018.pdf
_version_	1747818326895099904

Synthesis and characterization of fibrous silica zsm-5 for methanol to olefin reaction

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