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Cu/Mn-based mixed oxides derived from hydrotalcite-like precursors as catalysts for methane combustion

Paper ID Volume ID Publish Year Pages File Format Full-Text
39928 45840 2014 8 PDF Available
Title
Cu/Mn-based mixed oxides derived from hydrotalcite-like precursors as catalysts for methane combustion
Abstract

•First report on CH4 combustion on hydrotalcite-derived hopcalite-related catalysts.•Advantage of hydrotalcite-like mixed oxide catalyst precursors is demonstrated.•Composition–structure–activity relationship has been identified.

Hydrotalcite-like precursors containing Cu and Mn have been prepared by adding Al as an element promoting the layered structure formation. Materials with (Cu + Mn)/Al equal 3 or 8, and Cu/Mn equal 0.5 or 1, have been investigated and characterized with XRD, ICP OES, BET, SEM/EDS, TPR, FTIR, and XPS. Almost pure hydrotalcite-like phase has been obtained for Cu:Mn:Al ratio = 1.5:1.5:1. In other precursors, next to the hydrotalcite-like phase, a certain amount of poorly crystalline rhodochrosite (MnCO3)-like component (containing also some Cu and Al) was observed. Calcined solids were composed of Al-rich quasi amorphous mixed oxide phase, derived from hydrotalcite-like part of the precursor, and crystalline Cu1.5Mn1.5O4 spinel phase originating from the rhodochrosite-like component. In Al-poor samples, manganese present in excess with respect to the Cu1.5Mn1.5O4 stoichiometry appeared as crystalline Mn2O3. Addition of Ce and/or Zr dopants hindered the evolution of spinel phase. All catalysts derived from hydrotalcite-containing precursors were more active in CH4 combustion than the reference Cu–Mn mixed oxide of hopcalite-like stoichiometry. Catalysts activity depended on the (Cu + Mn)/Al and Cu/Mn ratios, whose proper choice ensured the balance between enhancing the content of highly dispersed mixed oxides derived from the hydrotalcite-like phase, and maximizing the content of the catalytically active transition metals. The latter was ensured by the lower relative Al content, while the lower value of Cu/Mn minimized formation of well crystalline Cu1.5Mn1.5O4. Addition of Ce and Zr improved the dispersion of mixed oxides obtained upon calcination, and helped to maintain the spreading of the active phase in the conditions of catalysis and/or steam ageing.

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Keywords
Hydrotalcite; Cu–Mn mixed oxides; Methane combustion
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Cu/Mn-based mixed oxides derived from hydrotalcite-like precursors as catalysts for methane combustion
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 474, 22 March 2014, Pages 87–94
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