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Selective oxidation of gas phase ammonia over copper chromites catalysts prepared by the sol–gel process

Paper ID Volume ID Publish Year Pages File Format Full-Text
50744 46812 2011 5 PDF Available
Title
Selective oxidation of gas phase ammonia over copper chromites catalysts prepared by the sol–gel process
Abstract

Selective gas phase oxidation of ammonia at atmospheric pressure was studied over a series of undoped and doped (Mn, Ag) copper chromites prepared by sol–gel process (SG). The catalysts were characterized by elemental analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and by adsorption microcalorimetry (AMC). A comparative study was made with a commercial copper chromite catalyst.The surface of the sol–gel undoped catalyst was found to be enriched in high valence chromium species with respect to the commercial one (Cr6+/Cr3+ = 0.56 versus 0.39 for commercial catalyst). From XPS, the Cu2+/(Cu° + Cu+) ratio was the same (ca. 5) in both catalysts but the sol–gel sample, contained twice more surface copper species (8.3 at.%) than the commercial one (17.6 at.%). Ammonia AMC experiments showed both a higher ammonia uptake and a wider strength distribution of adsorption sites on the sol–gel-prepared sample than on the commercial one. Improved catalytic performance in selective oxidation of ammonia at low temperature was obtained by simultaneous addition of silver and manganese to the sol–gel-prepared copper chromite.

Graphical abstractCopper chromites catalysts have been prepared by the sol–gel process. Their catalytic activity is superior to that of the corresponding commercial catalysts. The simultaneous addition of silver and manganese to the reference catalyst has profound influence both on ammonia conversion and selectivity to nitrogen.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Generation of acid sites in copper chromites by using Sol Gel process. ► Enrichment of catalysts surface with high valence chromium species (Cr6+). ► Crucial role of catalysts phase composition on NH3 conversion and N2 selectivity.

Keywords
Selective ammonia oxidation; Copper chromites; Sol–gel processing
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Selective oxidation of gas phase ammonia over copper chromites catalysts prepared by the sol–gel process
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Communications - Volume 15, Issue 1, 15 November 2011, Pages 32–36
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