Modeling CO Oxidation on Silica-Supported Iron Oxide under Transient Conditions

Randall, Harvey; Doepper, R.; Renken, Albert

doi:10.1021/ie960613d

Cited by 33 publications

(25 citation statements)

References 15 publications

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“…There is no signi®cant effect of temperature on 0 ss , indicating that the values of the activation energies of reduction and oxidation of the catalyst are close to each other. This result is in accordance with previous studies on the reduction of hematite by CO [6] and oxidation of magnetite by N 2 O [5]. As a matter of fact, reduction of hematite was shown to proceed through a three-step mechanism, the energies of activation of which are 75, 73 and 88 kJ/mol.…”

Section: Average Degree Of Reduction Of Catalyst At Steady-statesupporting

confidence: 92%

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Reduction of nitrogen oxides by carbon monoxide over an iron oxide catalyst under dynamic conditions

Randall

Doepper

Renken

1998

Applied Catalysis B: Environmental

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The reduction of NO and N 2 O by CO over a silica-supported iron oxide catalyst was investigated by the transient response method, with different initial oxidation states of the catalyst, i.e. completely reduced (Fe 3 O 4 ), or oxidised (Fe 2 O 3 ). The in¯uence of CO pre-adsorption was also studied. From the material balance on the gas phase species, it was shown that the composition of the catalyst changes during relaxation to steady-state. The degree of reduction of the catalyst at steady-state could thus be estimated. During the transient period, CO was shown to inhibit N 2 O as well as NO reductions by adsorption on reduced sites. The activity of the reduced catalyst was found to be substantially higher as compared to the oxidised catalyst for both reactions. On this basis, it was attempted to keep the catalyst in a reduced state by periodically reducing it with CO. As a result, a signi®cant increase in the performance of the reactor with respect to steady-state operation could be achieved for N 2 O reduction by CO. Finally, the dynamic behaviour of the N 2 O±CO and NO±CO reactions made it possible to evidence reaction steps, the occurrence of which could not be shown during our previous investigations on the separate interactions of the reactants with the catalyst. #

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Section: Average Degree Of Reduction Of Catalyst At Steady-statesupporting

confidence: 92%

“…The catalyst is thus reoxidised to Fe 2 O 3 . (O) stands for oxygen from the lattice of iron oxide [5,6]. The formation of atomic oxygen species adsorbed on Fe 2 O 3 , O(O), according to Eq.…”

Section: Introductionmentioning

confidence: 99%

Reduction of nitrogen oxides by carbon monoxide over an iron oxide catalyst under dynamic conditions

Randall

Doepper

Renken

1998

Applied Catalysis B: Environmental

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“…Oxidation of CO on iron oxides (Fe 2 O 3 ) has been previously studied both experimentally and theoretically [45][46][47][48]. The reaction is typically carried out at temperatures above 500 K in excess of oxygen, although the reaction may occur even in the absence of external oxygen over iron oxide nanoparticles [45].…”

Section: General Discussion and Proposed Mechanismmentioning

confidence: 99%

Monolayer iron oxide film on platinum promotes low temperature CO oxidation

Sun

Qin

Lewandowski

et al. 2009

Journal of Catalysis

221

236

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Abstract. CO oxidation on a clean Pt(111) single crystal and thin iron oxide films grown on Pt(111) was studied at different CO:O 2 ratios (between 1:5 and 5:1) and partial pressures up to 60 mbar at 400 -450 K. Structural characterization of the model catalysts was performed by scanning tunneling microscopy, low energy electron diffraction, Auger electron spectroscopy and temperature programmed desorption. It is found that monolayer FeO (111) films grown on Pt(111) are much more active than clean Pt(111) and nm-thick Fe 3 O 4 (111) films at all reaction conditions studied. Post-characterization of the catalysts revealed that at CO:O 2 >1 the FeO(111) film dewets the Pt surface with time, ultimately resulting in highly dispersed iron oxide particles on Pt(111). The film dewetting was monitored in situ by polarisation-modulated infrared reflection absorption spectroscopy. The reaction rate at 450 K exhibited first order for O 2 and non-monotonously depended on CO pressure. In O 2 -rich ambient the films were enriched with oxygen while maintaining the long range ordering.Based on the structure-reactivity relationships observed for the FeO/Pt films, we propose that the reaction proceeds through the formation of a well-ordered, oxygen-rich FeO x (1 < x < 2) film that reacts with CO through the redox mechanism. The reaction induced dewetting in fact deactivates the catalyst. The results may aid in our deeper understanding of reactivity of metal particles encapsulated by thin oxide films as a result of strong metal support interaction.

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“…Notably, iron or its compounds (alloys, oxides) can be used for the de-NO x process in two types of methods: primary and secondary methods. The application of iron (or/and its alloys/oxides) as a catalyst (secondary measures) in a separate reactor (similar to the concept of selective catalytic reduction, SCR) has been previously proposed [40][41][42][43][44]. For example, Randall et al investigated the reduction of NO and N 2 O by CO over silica-supported iron oxide (Fe 2 O 3 or Fe 3 O 4 ) catalysts.…”

Section: Application Of Iron In the De-nox Process: A Brief Analysismentioning

confidence: 99%

Investigations of the reduction of NO to N2 by reaction with Fe under fuel-rich and oxidative atmosphere

Lasek

2014

Heat Mass Transfer

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The limitation of nitrogen oxides (NO x ) emissions from stationary combustion chambers is still an important issue in the field of the natural environment protection. This paper describes the reduction of NO x in the presence of iron. A few new aspects of research describing the utilization of iron as an additive that influences NO x reduction at high temperatures are presented. In particular, the influence of the excess air number (k) on the NO x removal efficiency in the presence of Armco iron was determined. A [50 % increase in the efficiency was achieved at k = 0.6. The research was conducted using N 2 / NO mixed with a flue gas from carbon monoxide combustion. In addition, a correction factor (Arrhenius-type empirical equation) was determined, which enabled the calculation of the oxygen influence on the inhibition of the de-NO x reaction in the presence of iron. The NO x reduction was also tested using bearing steel samples. Finally, the use of iron in de-NO x processes under different combustion conditions is briefly reviewed and analyzed.

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Modeling CO Oxidation on Silica-Supported Iron Oxide under Transient Conditions

Cited by 33 publications

References 15 publications

Reduction of nitrogen oxides by carbon monoxide over an iron oxide catalyst under dynamic conditions

Reduction of nitrogen oxides by carbon monoxide over an iron oxide catalyst under dynamic conditions

Monolayer iron oxide film on platinum promotes low temperature CO oxidation

Investigations of the reduction of NO to N2 by reaction with Fe under fuel-rich and oxidative atmosphere

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