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Novel bifunctional NiMo/Al-SBA-15 catalysts for deep hydrodesulfurization: Effect of support Si/Al ratio

Paper ID Volume ID Publish Year Pages File Format Full-Text
43676 45982 2008 13 PDF Available
Title
Novel bifunctional NiMo/Al-SBA-15 catalysts for deep hydrodesulfurization: Effect of support Si/Al ratio
Abstract

A series of Al-containing mesoporous molecular sieves SBA-15 with different Si/Al molar ratios (50, 30, 20 and 10) was prepared by chemical grafting method using aluminum(III) chloride as alumina source. Mo and NiMo catalysts prepared using Al-SBA-15 supports were tested in the 4,6-dimethyldibenzothiophene (4,6-DMDBT) hydrodesulfurization (HDS) reaction. The synthesized solids were characterized by N2 physisorption, small- and wide-angle XRD, Py FT-IR, 27Al MAS-NMR, temperature-programmed reduction (TPR), UV–vis diffuse reflectance spectroscopy (DRS), chemical analysis and HRTEM. It was found that post-synthetic alumination of SBA-15 by reacting with AlCl3 has a little influence on the ordered mesoporous structure of the parent SBA-15 and leads to amorphous silicoaluminate materials with moderate Brönsted acidity. For all Si/Al molar ratios studied, tetrahedrally coordinated Al3+ cations predominated over octahedrally coordinated ones. However, as Al loading increases, the proportion of the latter ones was also increased. The dispersion of oxidic and sulfided Mo species increases with the incorporation of aluminum in the SBA-15 support due to the strong interaction of Mo and Ni species with aluminum atoms which serve as anchoring sites on the support surface. Catalytic activity of Mo and NiMo/SBA-15 catalysts increased with Al incorporation in the support reaching a maximum at Si/Al molar ratio of 20. High activity of NiMo/Al-SBA-15 catalysts in 4,6-DMDBT HDS can be attributed to a good dispersion of Ni and Mo active phases and to the bifunctional character of these catalysts. It was shown that both types of sites, coordinatively unsaturated sites of NiMoS active phase and Brönsted acid sites of the support participate in the catalytic transformations of 4,6-DMDBT.

Graphical abstractNiMo catalysts supported on Al-SBA-15 with different Si/Al molar ratios were prepared and tested in the 4,6-dimethyldibenzothiophene HDS. These catalysts were able to isomerize methyl groups of 4,6-DMDBT prior to its desulfurization.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
NiMo catalysts; Al-SBA-15; Deep hydrodesulfurization; 4,6-Dimethyldibenzothiophene; Bifunctional catalysts
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Novel bifunctional NiMo/Al-SBA-15 catalysts for deep hydrodesulfurization: Effect of support Si/Al ratio
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 335, Issue 2, 8 February 2008, Pages 159–171
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