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Structural, acidic and catalytic features of transition metal-containing molecular sieves in the transformation of C4 hydrocarbon

Paper ID Volume ID Publish Year Pages File Format Full-Text
42058 45909 2010 11 PDF Available
Title
Structural, acidic and catalytic features of transition metal-containing molecular sieves in the transformation of C4 hydrocarbon
Abstract

MCM-41 mesoporous materials and silicoaluminophosphates (SAPO-5) were prepared by gel hydrothermal crystallization. Both series of materials were modified by transition metals (chromium or iron close to 1 wt%). The synthesized solids were characterized by chemical analysis, XRD, nitrogen adsorption–desorption isotherms, SEM, EPR, XPS, IR of ammonia or pyridine adsorption studies, and 29Si, 27Al and 31P NMR. The catalysts were evaluated in the n-butane isomerization in order to assess their properties with regard to alkane transformations. The properties of the solids were modified by adding metals that altered the morphology, structural features and acidic character of the solids and result in an efficient performance in the transformation of n-butane in comparison with the pure counterparts. The introduction of Cr or Fe enhanced the catalytic ability of silicoaluminophosphates to produce isobutane. Fe and Cr modified silicoaluminophosphates were shown to be more efficient in the transformation of n-butane in comparison with the MCM-41 analogues. However, the activity of these iron-containing molecular sieves was considered too low in comparison with performances of iron-modified modernite. This was ascribed to an initial redox C4 activation step occurring in synergy with Brønsted sites with sufficient acid strength which is indeed higher than that provided by MCM-41 and SAPO molecular sieves.

Graphical abstract27Al NMR spectra show that silicoaluminophosphates have a large amount of EFAL species that provide Lewis acid sites on hydrothermally synthesized molecular sieves, when combined with EFW Cr2O3 and Fe2O3. These species, mainly Fe2O3, are able to catalyze the transformation of n-butane, in contrast to their analogues, the pure MCM-41 materials.Figure optionsDownload full-size imageDownload high-quality image (51 K)Download as PowerPoint slide

Keywords
Alkane activation; Acidic measurements; Molecular sieves; Isobutane; NMR; SEM
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Structural, acidic and catalytic features of transition metal-containing molecular sieves in the transformation of C4 hydrocarbon
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 382, Issue 1, 30 June 2010, Pages 10–20
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