fulltext.study @t Gmail

Oxidative coupling of methane: Influence of the phase composition of silica-based catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
41216 45881 2011 12 PDF Available
Title
Oxidative coupling of methane: Influence of the phase composition of silica-based catalysts
Abstract

A simple solid-phase synthesis technique was applied to prepare a series of silica-based composite materials. Each material contains tungsten, manganese and an alkali oxide. To determine the influence of the alkali nature on the catalytic properties of SiO2-based composites, a W–Mn/SiO2 material without any alkali was prepared. In addition, material containing tungsten, manganese and lithium without SiO2 was synthesized. The composites were studied by XRD, TPR, BET, XPS, SDB/SEM and EDS methods. A thorough analysis of the phase parameters, which were crystallized in alkali-doped W–Mn/SiO2 catalysts and determined by XRD, was performed for the first time. Most synthesized materials demonstrated higher catalytic activity in the oxidative coupling of methane (OCM) in comparison with the analogous materials prepared according the convenient wet impregnation method. The OCM reaction was carried out without any dilution of the methane–oxygen mixture. The results of catalytic tests were interpreted in relation to the catalyst silica-matrix phase composition. It was found that two polymorphic phases of SiO2 coexist in each composite material. These phases are cristobalite and quartz in Li- and Na-containing material or cristobalite and tridymite in K-, Rb- and Cs-containing materials. The hypothetical T–x phase diagrams of Me2O–SiO2 (where Me is an alkali metal) systems were constructed to explain the coexistence of two phases of SiO2 in the studied catalysts.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (204 K)Download as PowerPoint slideHighlights► A solid-phase technique was applied for alkali–W–Mn/SiO2 catalyst preparation. ► The new alkali–W–Mn/SiO2 catalysts are efficient in the OCM reaction. ► A thorough phase analysis of the alkali–W–Mn/SiO2 catalysts was performed. ► The T–x phase diagrams of Me2O–SiO2 (Me = alkali metal) systems were constructed. ► The catalytic results are interpreted in terms of the silica phase composition.

Keywords
Oxidative coupling of methane; Alkali-metal–W–Mn/SiO2 catalysts; Solid-phase synthesis technique; SiO2 phase composition
First Page Preview
Oxidative coupling of methane: Influence of the phase composition of silica-based catalysts
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 406, Issues 1–2, 18 October 2011, Pages 1–12
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