Aromatization of alkanes over Pt promoted conventional and mesoporous gallosilicates of MEL zeolite

Handle URI:
http://hdl.handle.net/10754/600097
Title:
Aromatization of alkanes over Pt promoted conventional and mesoporous gallosilicates of MEL zeolite
Authors:
Akhtar, M. N.; Al-Yassir, N.; Al-Khattaf, S.; Čejka, Jiří
Abstract:
Aromatization of hexane and propane was investigated over Pt promoted mesoporous gallium-containing HZSM-11 with controlled mesoporosity generated by desilication. Prepared catalysts were characterized by nitrogen adsorption, X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared of chemisorbed pyridine, and NH 3 temperature programmed desorption confirming the development of intracrystalline mesoporosity of Ga-containing HZSM-11. The catalytic activities, which were compared in the aromatization of n-hexane and propane, increased upon desilication. The aromatization of n-hexane decreased in the following order, Pt/mesoporous GaZSM-11 Pt/conventional GaZSM-11 mesoporous GaZSM-11 > conventional GaZSM-11. Hexane conversion reached 70.1% over mesoporous Pt/GaZSM-11 with Si/Ga of 61, as compared with 29.6 and 24.9% for corresponding mesoporous and conventional GaZSM-11 (Si/Ga = 94), respectively, for experiments at liquid hour space velocity of 3.6 h -1, and 540 °C. Comparison of BTX (benzene-toluene-xylene) selectivity at the conversion level of ∼21.0% revealed that Pt/mesoporous GaZSM-11 is more selective than corresponding mesoporous and conventional GaZSM-11. The BTX selectivity over Pt/mesoporous GaZSM-11 (Si/Ga = 94), which showed strong dependence on the conversion, reached 28.2%, whereas over corresponding mesoporous and conventional GaZSM-11catalysts reached 19.1% and 5.5%, respectively. A higher conversion and better selectivity can be attributed to the improved accessibility to the active extra-framework Ga species owing to the generation of mesopores inside the zeolite particles and shortening the contact time. It is worth mentioning that the prepared catalysts exhibited quite low activity in propane aromatization but exhibiting similar trends as for hexane aromatization. © 2011 Elsevier B.V. All rights reserved.
Citation:
Akhtar MN, Al-Yassir N, Al-Khattaf S, Čejka J (2012) Aromatization of alkanes over Pt promoted conventional and mesoporous gallosilicates of MEL zeolite. Catalysis Today 179: 61–72. Available: http://dx.doi.org/10.1016/j.cattod.2011.06.036.
Publisher:
Elsevier BV
Journal:
Catalysis Today
Issue Date:
Jan-2012
DOI:
10.1016/j.cattod.2011.06.036
Type:
Conference Paper
ISSN:
0920-5861
Sponsors:
The authors would like to express their appreciations to King Abdulaziz City for Science and Technology for their financial support under project No. 12-3MT. The financial support made by King Abdullah University of Science and Technology (KAUST) (Award No. K-C1-019-12) is highly appreciated. The authors would like also to extend their appreciation to the support from King Fahd University of Petroleum and Minerals.
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DC FieldValue Language
dc.contributor.authorAkhtar, M. N.en
dc.contributor.authorAl-Yassir, N.en
dc.contributor.authorAl-Khattaf, S.en
dc.contributor.authorČejka, Jiříen
dc.date.accessioned2016-02-28T07:58:45Zen
dc.date.available2016-02-28T07:58:45Zen
dc.date.issued2012-01en
dc.identifier.citationAkhtar MN, Al-Yassir N, Al-Khattaf S, Čejka J (2012) Aromatization of alkanes over Pt promoted conventional and mesoporous gallosilicates of MEL zeolite. Catalysis Today 179: 61–72. Available: http://dx.doi.org/10.1016/j.cattod.2011.06.036.en
dc.identifier.issn0920-5861en
dc.identifier.doi10.1016/j.cattod.2011.06.036en
dc.identifier.urihttp://hdl.handle.net/10754/600097en
dc.description.abstractAromatization of hexane and propane was investigated over Pt promoted mesoporous gallium-containing HZSM-11 with controlled mesoporosity generated by desilication. Prepared catalysts were characterized by nitrogen adsorption, X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared of chemisorbed pyridine, and NH 3 temperature programmed desorption confirming the development of intracrystalline mesoporosity of Ga-containing HZSM-11. The catalytic activities, which were compared in the aromatization of n-hexane and propane, increased upon desilication. The aromatization of n-hexane decreased in the following order, Pt/mesoporous GaZSM-11 Pt/conventional GaZSM-11 mesoporous GaZSM-11 > conventional GaZSM-11. Hexane conversion reached 70.1% over mesoporous Pt/GaZSM-11 with Si/Ga of 61, as compared with 29.6 and 24.9% for corresponding mesoporous and conventional GaZSM-11 (Si/Ga = 94), respectively, for experiments at liquid hour space velocity of 3.6 h -1, and 540 °C. Comparison of BTX (benzene-toluene-xylene) selectivity at the conversion level of ∼21.0% revealed that Pt/mesoporous GaZSM-11 is more selective than corresponding mesoporous and conventional GaZSM-11. The BTX selectivity over Pt/mesoporous GaZSM-11 (Si/Ga = 94), which showed strong dependence on the conversion, reached 28.2%, whereas over corresponding mesoporous and conventional GaZSM-11catalysts reached 19.1% and 5.5%, respectively. A higher conversion and better selectivity can be attributed to the improved accessibility to the active extra-framework Ga species owing to the generation of mesopores inside the zeolite particles and shortening the contact time. It is worth mentioning that the prepared catalysts exhibited quite low activity in propane aromatization but exhibiting similar trends as for hexane aromatization. © 2011 Elsevier B.V. All rights reserved.en
dc.description.sponsorshipThe authors would like to express their appreciations to King Abdulaziz City for Science and Technology for their financial support under project No. 12-3MT. The financial support made by King Abdullah University of Science and Technology (KAUST) (Award No. K-C1-019-12) is highly appreciated. The authors would like also to extend their appreciation to the support from King Fahd University of Petroleum and Minerals.en
dc.publisherElsevier BVen
dc.subjectAlkane aromatizationen
dc.subjectDesilicationen
dc.subjectGaHZSM-11en
dc.subjectIntracrystalline mesoporosityen
dc.subjectPlatinumen
dc.subjectZSM-11en
dc.titleAromatization of alkanes over Pt promoted conventional and mesoporous gallosilicates of MEL zeoliteen
dc.typeConference Paperen
dc.identifier.journalCatalysis Todayen
dc.contributor.institutionJ. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, V.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republicen
dc.contributor.institutionCenter of Research Excellence in Petroleum Refining and Petrochemicals, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabiaen
kaust.authorAkhtar, M.N.en
kaust.authorAl-Yassir, N.en
kaust.authorAl-Khattaf, S.en
kaust.grant.fundedcenterKAUST Center In Development at KFUPMen
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