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Gas phase Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam over mesoporous, microporous and amorphous Nb2O5/silica catalysts: A comparative study

Paper ID Volume ID Publish Year Pages File Format Full-Text
55217 47043 2012 11 PDF Available
Title
Gas phase Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam over mesoporous, microporous and amorphous Nb2O5/silica catalysts: A comparative study
Abstract

The gas phase Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam was investigated over niobium containing mesoporous (Nb-MCM-41, Nb-HMS and Nb-SBA-15), microporous (Nb-Beta zeolite) and amorphous (Nb impregnated on SiO2) catalysts. A relation between catalytic activities, structural and the acidic properties was derived. The catalysts Nb2O5/SiO2, Nb-MCM-41, Nb-SBA-15, and Nb-HMS resulted in higher cyclohexanone oxime conversion and caprolactam selectivity compared with Nb-Beta zeolite. Almost 100% cyclohexanone oxime conversion and up to 98% caprolactam selectivity were achieved over Nb2O5/SiO2 catalyst. Further, the catalytic activity results of Nb-MCM-41 are fairly similar to Nb2O5/SiO2. The high activity of both catalysts is related to vicinal silanol groups and silanol nests with weak acidity and negligible Brønsted acid sites. The physico-chemical properties of the investigated catalysts were characterized by various techniques including X-ray diffraction, N2 physisorption, Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance, atomic emission spectroscopy (ICP-AES), and Raman spectroscopy. Catalyst acidity was measured by NH3-TPD and pyridine adsorbed FTIR spectroscopy. The structural characterization results revealed that Nb was incorporated into the mesoporous and microporous materials framework.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (101 K)Download as PowerPoint slideHighlights► Highly efficient, inexpensive Nb2O5/SiO2 catalyst was developed for the Beckmann rearrangement. ► 100% cyclohexanone oxime conversion and 98% caprolactam selectivity were achieved. ► The superior performance is accompanied by highly dispersed Nb2O5 in silica matrix and negligible Brønsted acid sites. ► The catalysts Nb2O5/SiO2, Nb-MCM-41, Nb-SBA-15, and Nb-HMS resulted in higher activity compared with Nb-Beta zeolite.

Keywords
Nb2O5/SiO2; Mesoporous materials (M41S structure); Microporous material (Beta zeolite); Gas phase Beckmann rearrangement reaction; Cyclohexanone oxime; Caprolactam
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Gas phase Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam over mesoporous, microporous and amorphous Nb2O5/silica catalysts: A comparative study
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 198, Issue 1, 30 December 2012, Pages 289–299
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