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On the reducibility of sulfated Pt/CeXZr1−XO2 solids: A coupled thermogravimetric FT-IR study using CO as the reducing agent

Paper ID Volume ID Publish Year Pages File Format Full-Text
46653 46444 2012 10 PDF Available
Title
On the reducibility of sulfated Pt/CeXZr1−XO2 solids: A coupled thermogravimetric FT-IR study using CO as the reducing agent
Abstract

The reducibility of sulfate species by CO was studied over ceria and Ce0.63Zr0.37O2 mixed oxide with or without platinum, using infrared spectroscopy and thermogravimetry. The mechanism for sulfate reduction appeared to be based on three main points. Firstly, the exchange between surface and bulk-like sulfate species is required. The sulfate reduction indeed occurs at the oxide surface and bulk-like species need to migrate toward the surface to be further reduced. Secondly, it was observed that surface sulfate species are more easily reduced by CO on the reduced oxide. Therefore, platinum loading which favors the oxide reduction, also favors the sulfate reduction by CO. Finally, the reduction of sulfated Pt-free samples occurs in only one step, which is linked to the own reducibility of the surface sulfate species, probably through a direct interaction with CO. The amount of sulfur stored from sulfate reduction with CO is markedly more important than the one detected from reduction with H2. Furthermore, the oxygen storage capacity (OSC) for sulfated samples is higher than the one for sulfate-free samples. This is tentatively explained by the partial replacement of oxygen by sulfur atoms in the compound lattice.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We propose a mechanism for sulfate reduction by CO over ceria–zirconia oxides using FTIR and ATG. ► The mechanism involves a migration step between bulk-like and surface sulfate species. ► The platinum promoting effect would be directly linked with the better oxide reducibility. ► The oxide reduction is always concomitant to the sulfates one. ► The higher OSC of sulfated Ce-based catalyst is due to the replacement of some oxygen by sulfur atoms.

Keywords
Three way catalysts; Oxygen storage capacity; Ceria–zirconia; Platinum; Sulfate; Sulfur dioxide; Carbon monoxide; IR spectroscopy; Thermogravimetry
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On the reducibility of sulfated Pt/CeXZr1−XO2 solids: A coupled thermogravimetric FT-IR study using CO as the reducing agent
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 119–120, 30 May 2012, Pages 207–216
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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