fulltext.study @t Gmail

On the nature of active sites and catalytic activity for OCM reaction of alkaline-earth oxides-neodymia catalytic systems

Paper ID Volume ID Publish Year Pages File Format Full-Text
42125 45911 2010 7 PDF Available
Title
On the nature of active sites and catalytic activity for OCM reaction of alkaline-earth oxides-neodymia catalytic systems
Abstract

The work investigates the relationship between the surface basicity and catalytic activity for C2+ formation over equimolecular mixtures of alkaline-earth oxides (BeO, MgO, CaO and SrO) with Nd2O3. The concentration as well as the evolution of surface carbonate species with temperature, reflecting the basic properties of mixed oxides, was analyzed by TPD, XPS and IR methods to obtain information on the reaction mechanism. The concentration of surface basic sites contributing to the formation of C2+ was determined by measuring the amount of evolved CO2 in the 300–820 °C temperature range. The experimental data showed that the higher was the catalyst basicity the better was the efficiency for selectively converting methane to C2+. The turnover frequency (TOF) values were calculated by quantitatively determining the total number basic sites retaining CO2. The experimental results led to the idea that methane is converted to products on two types of active sites by independent pathways. The alkaline active sites are responsible for C2+ formation whereas the acidic sites with low affinity for carbonate formation are responsible for methane combustion. The synergetic effect between a selected alkaline-earth oxide (MgO) and a series of rare-oxide on the OCM catalytic activity has been also investigated.

Graphical abstractThe study investigates the relationship between the surface basicity and catalytic activity for C2+ formation over equimolecular mixtures of alkaline-earth oxides with Nd2O3. The experimental results led to the idea that methane is converted to products on two distinct types of active sites by independent pathways. The synergetic effect between alkaline-earth oxide and a series of rare-oxide on the OCM catalytic activity have been also studied.Figure optionsDownload full-size imageDownload high-quality image (82 K)Download as PowerPoint slide

Keywords
Oxidative coupling of methane; Methane oxidative conversion; Basicity of oxide surface; Lanthanide-alkaline-earth oxide catalysts
First Page Preview
On the nature of active sites and catalytic activity for OCM reaction of alkaline-earth oxides-neodymia catalytic systems
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 375, Issue 1, 26 February 2010, Pages 172–178
Authors
, , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis