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Synthesis and characterization of conventional and mesoporous Ga-MFI for ethane dehydrogenation

Paper ID Volume ID Publish Year Pages File Format Full-Text
43493 45972 2008 9 PDF Available
Title
Synthesis and characterization of conventional and mesoporous Ga-MFI for ethane dehydrogenation
Abstract

Gallium was for the first time incorporated into the crystal structure of a mesoporous MFI zeolite. As a reference material, a well-defined conventional MFI zeolite with gallium incorporated was also synthesized. The materials were characterized by XRPD, NH3-TPD, elemental analysis, N2 physisorption measurements, SEM, FT-IR as well as 29Si and 71Ga MAS NMR spectroscopy. The Ga contents correspond to molar ratios of Si/Ga = 43 and 38 for the conventional and mesoporous Ga-MFI, respectively. The different types of analysis show that two almost identical zeolites were synthesized, the main difference being the morphology of the crystals. The catalytic properties of the samples were tested in ethane dehydrogenation at 823 K and at atmospheric pressure. The two Ga-MFI samples differ greatly in conversion of ethane, as a result of their difference in porosity, and it is found that the conversion is significantly improved by introducing mesopores into the structure. The major product is ethene for the conventional Ga-MFI, but there are significant amounts of benzene and toluene by-products for the mesoporous Ga-MFI. The 71Ga isotropic chemical shift and second-order quadrupolar effect parameter is reported for tetrahedral Ga incorporated in the MFI structure and it is shown that absorbed water molecules have an important impact on the 71Ga electric field gradients and thereby on the quantitative evaluation of the 71Ga MAS NMR intensities.

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Keywords
Ga-MFI zeolites; Mesoporous; Ethane dehydrogenation; Aromatization; 71Ga MAS NMR
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Synthesis and characterization of conventional and mesoporous Ga-MFI for ethane dehydrogenation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 348, Issue 2, 15 October 2008, Pages 257–265
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
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