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Neodymium doped alkaline-earth oxide catalysts for propane oxidative dehydrogenation. Part I. Catalyst characterisation

Paper ID Volume ID Publish Year Pages File Format Full-Text
42518 45929 2009 8 PDF Available
Title
Neodymium doped alkaline-earth oxide catalysts for propane oxidative dehydrogenation. Part I. Catalyst characterisation
Abstract

Two series of alkaline earth oxides (AEO) of Mg, Ca, and Sr doped with 5 mol% Nd2O3 have been synthesised by two procedures: (i) evaporation of nitrate solutions with subsequent nitrate decomposition (designated Ev) and (ii) sol–gel method (designated SG). The catalysts samples characterisation was performed by ICP chemical analysis, BET specific surface area measurement, FTIR spectroscopy, CO2 TPD, powder XRD, and XPS. The XRD data have shown presence of solid solutions of both Nd in AEO and of alkaline earth elements in Nd2O3. The structural defects that appeared under Nd incorporation into AEO lattice were studied by detailed XRD peak profiles analysis. They were agglomerated or dispersed, their relative amounts depending on the preparation procedure and on the alkaline-earth ion size match with Nd3+. The dispersed local defects were favored by the sol–gel method and by close cation radii dimensions, whereas Nd3+ agglomerates formed mainly on Mg-containing samples and were favored by evaporation. The catalyst basicity has been observed to follow the expected order Mg < Ca < Sr and to increase under Nd3+ incorporation into AEO lattice, being stronger for SG samples than for Ev ones. The created cationic vacancies under neodymium incorporation increased the basic character of nearby oxygen anions by rendering them coordinatevely unsaturated. XPS results have shown presence of carbonate species and small enrichment in Nd on the surface.

Graphical abstractTwo series of 5 mol% Nd2O3–AEO (AEO = MgO, CaO, SrO) were synthesised by (i) evaporation of nitrate solutions followed by nitrate decomposition and (ii) sol–gel technique. The samples were characterised by different methods. The structural defects that appeared under Nd incorporation into AEO lattice were studied by detailed XRD peak profiles analysis and estimation of structural parameters. Structural parameters calculated from XRD patterns for the predominant crystalline phases: (a) average grain dimension (〈D〉), (b) unit cell mass modification Δm, (c) lattice microstrain factor (〈S〉) and (d) lattice profile anisotropy factor (ΔΦ).Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Nd–alkaline-earth oxide catalysts; Sol–gel preparation; Basicity; Lattice defects
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Neodymium doped alkaline-earth oxide catalysts for propane oxidative dehydrogenation. Part I. Catalyst characterisation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 359, Issues 1–2, 15 May 2009, Pages 47–54
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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