Crystallite size effects in the low-temperature oxidation of ammonia over supported platinum

Ostermaier, J.J.; Katzer, J.R.; Manogue, W.H.

doi:10.1016/0021-9517(74)90292-9

Cited by 89 publications

(40 citation statements)

References 31 publications

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“…Recent studies reveal that at low temperatures Ir-based catalysts are more active and selective to N 2 than Pt-based catalysts [5,15]. Moreover, the influence of the catalyst support and catalyst size effects on the reaction have been found [21,22]. In this work, ammonia oxidation by oxygen was investigated via temperature programmed desorption (TPD) under UHV conditions (\1 9 10 -9 Torr) on clean planar Ir(210) and clean faceted Ir(210) with a focus on structural and size effects in the reaction.…”

Section: Introductionmentioning

confidence: 99%

Selective Oxidation of Ammonia by Co-adsorbed Oxygen on Iridium Surfaces: Formation of N2O

2014

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Temperature programmed desorption is used to investigate ammonia oxidation by pre-adsorbed oxygen on planar Ir(210) and faceted Ir(210) with different facet sizes. Evidence is found for formation of N 2 O from both surfaces, which is the first observation of N 2 O production in catalytic ammonia oxidation under UHV conditions (\1 9 10 -9 Torr). The selectivity of the reaction to N 2 , N 2 O and NO can be tuned by oxygen pre-coverage, surface structure, and facet size. The reaction exhibits strong structure sensitivity on faceted Ir(210) versus planar Ir(210) and moderate size effects on faceted Ir(210) for average facet sizes of 5-14 nm. Graphical Abstract

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Section: Introductionmentioning

confidence: 99%

Selective Oxidation of Ammonia by Co-adsorbed Oxygen on Iridium Surfaces: Formation of N2O

2014

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“…Previous studies show that noble metals such as Pt is active for this reaction at low temperature but deactivate rapidly with time [7]. Silver based catalysts have a high activity for ammonia conversion, but the N 2 selectivity is relatively low at the temperature range investigated [8].…”

Section: Introductionmentioning

confidence: 99%

Selective catalytic oxidation of ammonia from MAP decomposition

Zhang

Yang

et al. 2007

Separation and Purification Technology

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The Cu/TiO 2 catalysts with different Cu loadings were prepared, and their performance in the selective catalytic oxidation of ammonia (SCO of NH 3 ) was compared with 10% Cu/Al 2 O 3 . The 10% Cu/TiO 2 has the best performance among its series for NH 3 conversion and N 2 selectivity. At 250• C, the 100% conversion of ammonia was achieved and the selectivity to N 2 came to 95%. The 10% Cu/TiO 2 catalyst has a much higher activity for the SCO of ammonia and a slightly lower N 2 selectivity than 10% Cu/Al 2 O 3 because of the higher oxygen mobility and lower oxygen bonding strength, which demonstrated that TiO 2 is a more suitable support than Al 2 O 3 for copper-based catalyst in the SCO of NH 3 . The mechanisms involved in the SCO of NH 3 reaction on the 10% Cu/TiO 2 catalyst have also been investigated using TPD, TPR as well as in situ DRIFTS methods.

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“…(b) The second approach for solving the problem of temperature control in the catalytic ammonia oxidation is a decrease of reaction temperature while keeping partial pressures in the kPa range; hereby reaction rates are reduced, and hence also the heat generation on the catalyst surface. Respective studies were limited to temperatures below 300 • C [1,[11][12][13], and therefore no [1,13]; Pt wire: [11,12]). (c) Rebrov et al extended the range of temperaturecontrolled ammonia oxidation near atmospheric pressure to 360 • C applying micro-structured reactors ( [14][15][16]), which are known for their inherently good heat removal.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of ammonia oxidation over Pt foil studied in a micro-structured quartz-reactor

Kraehnert

Baerns

2008

Chemical Engineering Journal

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The kinetics of Pt-catalyzed ammonia oxidation on polycrystalline Pt were investigated at partial pressures of ammonia and oxygen up to 6 kPa and temperatures between 286 and 385• C, applying a micro-structured reactor that ascertained temperature control of the exothermic reaction. Using literature-based mechanistic models, a micro-kinetic model was derived based on parameter optimization and a model discrimination procedure. The model described the rates of formation of all nitrogen-containing products, i.e. N 2 , N 2 O and NO. Catalyst characterization of platinum samples by electron microscopy indicated that reaction-induced restructuring of the Pt surface limited the accuracy of derived kinetic parameters already at the low temperature applied in this work. Despite of necessary simplifications, the best-fitting kinetic model predicted reasonable product selectivities for the reaction conditions of an industrial ammonia burner.

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Crystallite size effects in the low-temperature oxidation of ammonia over supported platinum

Cited by 89 publications

References 31 publications

Selective Oxidation of Ammonia by Co-adsorbed Oxygen on Iridium Surfaces: Formation of N2O

Selective Oxidation of Ammonia by Co-adsorbed Oxygen on Iridium Surfaces: Formation of N2O

Selective catalytic oxidation of ammonia from MAP decomposition

Kinetics of ammonia oxidation over Pt foil studied in a micro-structured quartz-reactor

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