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

Paper ID Volume ID Publish Year Pages File Format Full-Text
55614 47059 2012 12 PDF Available
Title
Aromatization of alkanes over Pt promoted conventional and mesoporous gallosilicates of MEL zeolite
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 NH3 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.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (112 K)Download as PowerPoint slideHighlights► Conventional and mesoporous Ga-HZSM-11 as catalysts. ► Catalysts for aromatization of C3 and C6. ► Mesoporous Ga-HZSM-11 was obtained by desilication. ► Conversion increase upon desilication.

Keywords
Alkane aromatization; ZSM-11; GaHZSM-11; Desilication; Intracrystalline mesoporosity; Platinum
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Aromatization of alkanes over Pt promoted conventional and mesoporous gallosilicates of MEL zeolite
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 179, Issue 1, 5 January 2012, Pages 61–72
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us