Reversed Flow Gas Chromatography: A Tool for Instantaneous Monitoring of the Concentrations of Reactants and Products in Heterogeneous Catalytic Processes

Gavril, Dimitrios

doi:10.1081/jlc-120013996

Cited by 14 publications

(1 citation statement)

References 27 publications

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“…[60,61,62,63]. During the last decade, a large number of physicochemical quantities related to gas-solid interactions have also been determined by RF-IGC methodologies [64,65,66,67,68,69,70]. The determination of these quantities gives important information for the mechanism of the respective processes and permits the characterization of the studied solids.…”

Section: Methodsmentioning

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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