Dynamic behavior of automotive catalysts. 1. Catalyst oxidation and reduction

Herz, Richard K.

doi:10.1021/i300003a007

Cited by 103 publications

(30 citation statements)

References 13 publications

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“…The function of cerium as oxygen storage component is based on its ability to form both three and four valent oxides (Herz, 1981). Under net oxidizing conditions the following Ce oxide reaction is the most representative for the realization of oxygen storage:…”

Section: Oxygen Storage Submodelmentioning

confidence: 99%

Modeling dynamic phenomena in 3-way catalytic converters

Koltsakis

Stamatelos

1999

Chemical Engineering Science

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Mathematical modeling of 3-way catalytic converter (3WCC) operation is increasingly employed in automotive catalyst and converter systems optimization. The majority of the models employed in this direction employ a &quasi-steady' approach in the reaction kinetics computations. This approach is useful in predicting real-world performance of the catalyst. However, certain improvements, that are produced by the application of specially tuned redox oscillations, can not be predicted. This paper presents an approach embodying certain types of dynamic phenomena into an existing 3-WCC quasi-steady model. The dynamic model developed according to this approach is validated against literature data and results from experimental investigations. It is con"rmed, that the catalyst behavior under dynamic exhaust composition conditions signi"cantly di!ers from what is predicted under the quasi-steady-state assumption. More speci"cally, oxygen storage and the transient character of water gas shift reaction are shown to a!ect dynamic behavior. The results of this investigation encourage further application of mathematical modeling in areas like lambda control strategy optimization, which lied beyond the scope of traditional 3WCC models.

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Section: Oxygen Storage Submodelmentioning

confidence: 99%

Modeling dynamic phenomena in 3-way catalytic converters

Koltsakis

Stamatelos

1999

Chemical Engineering Science

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“…Typical catalytic poisons are sulfur compounds, hydrocyanic acid, mercury, compounds of phosphorous, etc. [6][7][8]. The most common effect of such impurities is to decrease the number of reactive sites on the catalytic surface, thereby greatly reducing the efficiency of the process.…”

mentioning

confidence: 99%

Model for the catalytic oxidation of CO, including gas-phase impurities and CO desorption

Rikvold

2013

Phys. Rev. E

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We present results of kinetic Monte Carlo simulations of a modified Ziff-Gulari-Barshad model for the reaction CO+O → CO2 on a catalytic surface. Our model includes impurities in the gas phase, CO desorption, and a modification known to eliminate the unphysical O poisoned phase. The impurities can adsorb and desorb on the surface, but otherwise remain inert. In a previous work that did not include CO desorption [G. M. Buendía and P. A. Rikvold, Phys. Rev. E, 85 031143 (2012)], we found that the impurities have very distinctive effects on the phase diagram and greatly diminish the reactivity of the system. If the impurities do not desorb, once the system reaches a stationary state, the CO2 production disappears. When the impurities are allowed to desorb, there are regions where the CO2 reaction window reappears, although greatly reduced. Following experimental evidence that indicates that temperature effects are crucial in many catalytic processes, here we further analyze these effects by including a CO desorption rate. We find that the CO desorption has the effect to smooth the transition between the reactive and the CO rich phase, and most importantly it can counteract the negative effects of the presence of impurities by widening the reactive window such that now the system remains catalytically active in the whole range of CO pressures.

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“…In air atmosphere, however, the highest performance is observed for the 1 wt% CeO 2 -doped 40Pt/C catalyst. This is owing to both oxygen storage capacity (OSC) of CeO 2 and its ability to exchange rapidly oxygen with buffer oxygen, that is, partial pressure oscillation [56]. It can be noted that the effect of CeO 2 in the air atmosphere is much pronounced, to an extent of 100% (Fig.…”

Section: Nanophase Pt-ceo 2 /C Electrocatalystsmentioning

confidence: 99%

Highly Dispersed and Nano-sized Pt-based Electrocatalysts for Low-Temperature Fuel Cells

Lim

Lee

2008

Catal Surv Asia

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Among metals, Pt is so far the best material to be used as anode and cathode in low-temperature fuel cells. However, Pt has the drawback of being expensive and easily CO-poisoned. Thus, to produce useful electrocatalysts, significant efforts have been made worldwide on developing Pt-based catalysts with low Pt contents as well as searching for alternative materials with high catalytic activity for anodic and cathodic reactions in low-temperature fuel cells. This article presents the development of highly dispersed and nano-sized Pt-based electrocatalysts synthesized by several new methods based on our experimental results. In the case of anode materials, our proposed new method consists of the synthesis of Pt-based nanoparticles in order to maximize their surface availability, combined with the use of secondary metals that promote the oxidations of methanol and CO. On the other hand, for the cathode materials, the use of the Pt catalysts mixed with metal oxides enhances their oxygen reduction reaction (ORR) activity. We anticipate that the highly dispersed Ptbased nanoparticles introduced in this article will improve the performance of anode and cathode for low-temperature fuel cells.

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Dynamic behavior of automotive catalysts. 1. Catalyst oxidation and reduction

Cited by 103 publications

References 13 publications

Modeling dynamic phenomena in 3-way catalytic converters

Modeling dynamic phenomena in 3-way catalytic converters

Model for the catalytic oxidation of CO, including gas-phase impurities and CO desorption

Highly Dispersed and Nano-sized Pt-based Electrocatalysts for Low-Temperature Fuel Cells

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