H2 and CO2 coadsorption effects in CO adsorption over nanosized Au/γ-Al2O3 catalysts

Georgaka, A.; Gavril, Dimitrios; Loukopoulos, V. C.; Karaiskakis, George; Nieuwenhuys, B.E.

doi:10.1016/j.chroma.2008.07.092

Cited by 12 publications

(5 citation statements)

References 32 publications

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“…On the other hand, the assumption of zero CO surface coverage (Models A3 and B3) deteriorated the results significantly when H 2 is present in the reaction feed demonstrating that more CO adsorbed on the surface, which was in complete agreement with the previous findings [30].…”

Section: Preferential Co Oxidationsupporting

confidence: 88%

Analysis of reaction mechanisms and kinetics of preferential CO oxidation over Au/γ-Al2O3

Davran-Candan

Demir

Yıldırım

2011

Reac Kinet Mech Cat

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In this work, the mechanism and kinetics of the preferential CO oxidation over 0.5 wt. % Au/Al 2 O 3 catalyst was investigated. For CO oxidation, the reaction was found to follow a two-step Eley-Rideal-type mechanism, in which the formation and decomposition of the reaction intermediate took place at the gold-support interface. For the PROX case, on the other hand, Langmuir-Hinshelwood-type mechanisms seem to be also significant.

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Section: Preferential Co Oxidationsupporting

confidence: 88%

Analysis of reaction mechanisms and kinetics of preferential CO oxidation over Au/γ-Al2O3

Davran-Candan

Demir

Yıldırım

2011

Reac Kinet Mech Cat

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“…The performance of the Au/γ-Al 2 O 3 catalyst both under normal preferential oxidation (PROX)-type operation as well as for normal CO oxidation has been studied in detail in previous publications [48,53,54,55]. The findings of these studies are summarized in Figure 1, in which temperature variation plots of CO to CO 2 conversion, measured by the temperature programmed surface reaction (TPSR) technique, over the studied Au/γ-Al 2 O 3 catalyst both in the absence as well as in excess of H 2 , are shown.…”

Section: Resultsmentioning

confidence: 99%

“…The effects of H 2 and CO 2 on the rates related to the elementary steps of CO sorption over Au/γ-Al 2 O 3 have also been studied [54]. The experimental findings obtained both by TPSR, as well as by RF-IGC, indicated the “decomposition” of CO to CO 2 on the studied catalyst, in the absence of H 2 .…”

Section: Resultsmentioning

confidence: 99%

Kinetic Study of Oxygen Adsorption over Nanosized Au/γ-Al2O3 Supported Catalysts under Selective CO Oxidation Conditions

2012

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O 2 adsorption is a key process for further understanding the mechanism of selective CO oxidation (SCO) on gold catalysts. Rate constants related to the elementary steps of O 2 adsorption, desorption and surface bonding, as well as the respective activation energies, over a nanosized Au/γ-Al 2 O 3 catalyst, were determined by Reversed-Flow Inverse Gas Chromatography (RF-IGC). The present study, carried-out in a wide temperature range (50-300 C), both in excess as well as in the absence of H 2 , resulted in mechanistic insights and kinetic as well as energetic comparisons, on the sorption processes of SCO reactants. In the absence of H 2 , the rate of O 2 binding, over Au/γ-Al 2 O 3 , drastically changes with rising temperature, indicating possible O 2 dissociation at elevated temperatures. H 2 facilitates stronger O 2 bonding at higher temperatures, while low temperature binding remains practically unaffected. The lower energy barriers observed, under H 2 rich conditions, can be correlated to O 2 dissociation after hydrogenation. Although, H 2 enhances both selective CO reactant's desorption, O 2 desorption is more favored than that of CO, in agreement with the well-known mild bonding of SCO reactant's at lower temperatures. The experimentally observed drastic change in the strength of CO and O 2 binding is consistent both with well-known high activity of SCO at ambient temperatures, as well as with the loss of selectivity at higher temperatures.

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“…Georgaka et al also reported that oxygen concentrations higher than the stoichiometric amount were necessary in order to obtain high CO conversion rates over particulate Au catalysts within the temperature range where PEM fuel cells operate. 24 Mozer et al also studied the effect of O 2 concentration on selective CO oxidation over Cu promoted particulate Au/Al 2 O 3 catalysts. For this purpose, they investigated the variation in CO conversion and selectivity for CO oxidation using 0.5%, 1% and 1.5% O 2 in feed streams containing 1% CO and concluded that CO conversion increases with increasing O 2 concentration; however, there was a small decrease in CO oxidation selectivity at ratios well above stoichiometric, e.g.…”

Section: Effect Of O 2 Concentrationmentioning

confidence: 97%

Selective CO oxidation over monolithic AuMgO/Al₂O₃ catalysts

Özdemir

Önsan

Yıldırım

2011

J of Chemical Tech & Biotech

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H2 and CO2 coadsorption effects in CO adsorption over nanosized Au/γ-Al2O3 catalysts

Cited by 12 publications

References 32 publications

Analysis of reaction mechanisms and kinetics of preferential CO oxidation over Au/γ-Al2O3

Analysis of reaction mechanisms and kinetics of preferential CO oxidation over Au/γ-Al2O3

Kinetic Study of Oxygen Adsorption over Nanosized Au/γ-Al2O3 Supported Catalysts under Selective CO Oxidation Conditions

Selective CO oxidation over monolithic AuMgO/Al₂O₃ catalysts

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H2 and CO2 coadsorption effects in CO adsorption over nanosized Au/γ-Al2O3 catalysts

Cited by 12 publications

References 32 publications

Analysis of reaction mechanisms and kinetics of preferential CO oxidation over Au/γ-Al2O3

Analysis of reaction mechanisms and kinetics of preferential CO oxidation over Au/γ-Al2O3

Kinetic Study of Oxygen Adsorption over Nanosized Au/γ-Al2O3 Supported Catalysts under Selective CO Oxidation Conditions

Selective CO oxidation over monolithic AuMgO/Al2O3 catalysts

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Selective CO oxidation over monolithic AuMgO/Al₂O₃ catalysts