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Selective detection of reaction intermediates using concentration-modulation excitation DRIFT spectroscopy

Paper ID Volume ID Publish Year Pages File Format Full-Text
54926 47032 2013 7 PDF Available
Title
Selective detection of reaction intermediates using concentration-modulation excitation DRIFT spectroscopy
Abstract

Concentration-modulation excitation spectroscopy (MES) experiments in combination with phase-sensitive detection (PSD) were used to monitor the gas–solid interface by means of in operando diffuse reflectance infrared spectroscopy (DRIFT). The MES methodology is a powerful technique because it allows sensitive and selective spectroscopic detection and monitoring of the dynamic behavior of species directly involved in a reaction.In this work, c-MES was employed to monitor the adsorption of hydrogen and carbon dioxide and their reaction (reverse water gas shift) on a model Pd(1 wt.%)/γ-Ga2O3 catalyst. Details of the reaction mechanism could be reached: (i) H2 is dissociatively chemisorbed on the gallium oxide surface giving Ga–H species; (ii) CO2 is adsorbed giving rise of carbonate groups; (iii) on the gallia surface, carbonates are hydrogenated by Ga–H to produce formate species with different coordination, e.g. monodentate, bidentate and bridged formates, which in turn are decomposed into CO(g); (iv) the metal phase increases the formate surface concentration onto the gallia because of an efficient supply of atomic hydrogen via a spillover. Results also indicated that monodentate formates are the most reactive intermediate.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (179 K)Download as PowerPoint slideHighlights► Concentration-modulation excitation infrared spectroscopy was used to monitor surface intermediates. ► Reverse water gas shift reaction was investigated on a Pd(Ga)/Ga2O3 catalyst. ► Carbonates, formates and gallium hydride were selectively detected. ► Monodentate is the most reactive formate intermediate.

Keywords
DRIFT; Modulation excitation spectroscopy; Palladium-gallia; Formates; Reverse water gas shift reaction
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Selective detection of reaction intermediates using concentration-modulation excitation DRIFT spectroscopy
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 205, 30 April 2013, Pages 34–40
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