fulltext.study @t Gmail

Iron-catalyzed gas-phase epoxidation of propylene by N2O via halide-assisted oxygen transfer

Paper ID Volume ID Publish Year Pages File Format Full-Text
42894 45945 2008 9 PDF Available
Title
Iron-catalyzed gas-phase epoxidation of propylene by N2O via halide-assisted oxygen transfer
Abstract

The gas-phase epoxidation of propylene using nitrous oxide as an oxidant over bulk and supported iron-containing catalysts was studied. The presence of silica and an alkaline metal in both types of catalysts was found to be indispensable. Bulk catalysts formed in potassium–iron mixed silicates were studied, with respect to their crystalline structure, oxidation state and performance in propylene epoxidation. Over these catalysts a 69% selectivity to propylene oxide at 1.6% propylene conversion was reached. The presence of separated iron oxide phase was shown to promote the undesired allylic oxidation of propylene. Supported, halide-modified Fe-containing catalysts exhibit a superposition of two epoxidation routes. One, independent of air-pretreatment, shows similarity with that observed at bulky potassium–iron silicates; and the second, more selective, induced by air-pretreatment. The second mechanism, dominant in the first 30 min on stream, results in a maximum of 45.7% propylene conversion at 70% selectivity to propylene oxide. An improvement of the epoxidation activity was obtained, comprising reaction–reactivation switching steps. A reaction mechanism involving KCl as an oxygen transmitter and a metastable form of iron moieties is suggested.

Graphical abstractThe epoxidation of propylene using N2O over Fe-containing catalysts was studied. Silicate catalysts showed 69% selectivity to epoxide at 1.6% conversion. Supported, halide-modified catalysts exhibit two epoxidation routes: one, similar to that of silicates; and a second, more selective, air-induced, with a 45.7% conversion. A mechanism involving KCl as an oxygen transmitter is suggested.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Epoxidation; Propylene oxide; Nitrous oxide; Iron catalyst; Chlorohydrine
First Page Preview
Iron-catalyzed gas-phase epoxidation of propylene by N2O via halide-assisted oxygen transfer
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 347, Issue 1, 1 September 2008, Pages 72–80
Authors
, ,
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