ChemInform Abstract: THE DUAL STATE BEHAVIOR OF SUPPORTED NOBLE METAL CATALYSTS

Taylor, Kathleen C.; Sinkevitch, Robert M.; Klimisch, Richard L.

doi:10.1002/chin.197452053

Cited by 4 publications

(6 citation statements)

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“…This is different from the severely oxidized (and deactivated) condition which can be induced by heating Rh in an oxidizing environment at temperatures of 800 °C or so Schlatter et al, 1979b). The situation is similar to observations reported for Pt, Pd, and particularly Ru in a previous paper (Taylor et al, 1974), where an oxidizing pretreatment was found to enhance catalytic activity for the water-gas shift. The unique feature of the Rh behavior is that the enhancement is so easily reversed, requiring only 20-30 min in the simulated rich exhaust.…”

Section: Discussionsupporting

confidence: 90%

Three-Way Catalyst Response to Transients

Schlatter¹,

Mitchell²

1980

Ind. Eng. Chem. Prod. Res. Dev.

138

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Because the exhaust composition in closed-loop emission control systems fluctuates about the stoichiometric set point, there is considerable interest in understanding and improving catalyst behavior in this oscillating environment. We have measured adsorption capacities, responses to step changes in feedstream composition, and performance in cycled laboratory feedstreams in order to clarify features of the transient response of three-way catalysts. Our laboratory results are best explained on the basis of a temporary increase in water-gas shift activity rather than the more common oxygen storage explanation. The phenomenon is associated with the presence of rhodium in the catalyst and Is enhanced when cerium is also present. Sulfur dioxide in the feedstream was highly detrimental to the water-gas shift reaction; so the applicability of these results to the exhaust environment remains an open question.

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Section: Discussionsupporting

confidence: 90%

Three-Way Catalyst Response to Transients

Schlatter¹,

Mitchell²

1980

Ind. Eng. Chem. Prod. Res. Dev.

138

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“…It is favored not only for its high activity but also because under exhaust conditions it has been shown to be more selective to the formation of Ng over ammonia (2)(3)(4)(5)(6)(7)(8) than platinum or rhodium.…”

Section: Kinetic Procedures 4lmentioning

confidence: 99%

“…They also fit their data to a power rate law of the following form: Rate^o = 6.6x10^ exp(-19.7 ± 3.6 kcal/mole/RT) P°Q P°Q (5) Their reaction chamber was a closed system and the gas composition was monitored mass spectrometrically after passing through a capillary-type leak. It is interesting that while they reported zero order in both CO and NO proposed mechanism and assuming rapid equilibria establish ment, the rate of carbon dioxide production would be:…”

Section: 81mentioning

confidence: 99%

“…In contrast, Butler and Davis reported that N^O was not involved in any significant role in the NO-CO reaction system and that the order with respect to NO is +1 to 0 and is 0 for CO, Considering the similarities in reaction conditions, the differences in the results are striking; this is an illustration of an apparent weakness in both studies demonstrating the need for surface characterization of the catalyst. Neither study investi In an effort to characterize each state, Taylor, Sinkevitch and Klimisch (5) undertook an effort to distinguish the features of both by investigating the activities of ammonia decomposition, nitric oxide reduction and the CO-Hg and water-gas shift reactions. They found that the oxidized state was more active for each except for the overall removal rate of NO where both were equally effective.…”

Section: Imentioning

confidence: 99%

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Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces

Quick

1980

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Quick, Edward Edwards, "The interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces " (1979 INFORMATION TO USERSThis was produced from a copy of a document sent to us for microfilming. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the material submitted.The following explanation of techniques is provided to help you understand markings or notations which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure you of complete continuity. When an image on the film is obliterated with a round black mark it is anindication that the film inspector noticed either blurred copy because of movement during exposure, or duplicate copy. Unless we meant to delete copyrighted materials that should not have been filmed, you will find a good image of the page in the adjacent frame,.3. When a map, drawing or chart, etc., is part of the material being photo graphed the photographer has followed a definite method in "sectioning" the material. It is customary to begin filming at the upper left hand comer of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued agaun-beginning below the first row and continuing on until complete.

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“…The phenomenon was only eliminated when the catalyst was exposed to sulfur containing materials (Taylor and Klimisch, 1973). The application of physical methods of surface examination to characterize the two states of the catalyst gave no evidence that the so-called oxidized form of the catalyst is an oxide under the reaction conditions for NO reduction (Taylor, et al, 1974).…”

Section: Introductionmentioning

confidence: 99%

Catalytic Reduction of Nitric Oxide on Ruthenium

Klimisch¹,

Taylor²

1975

Product R&D

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The details of nitric oxide catalytic reduction by carbon monoxide and hydrogen over a supported ruthenium catalyst have been investigated. The feed stream used in these studies resembled automotive exhaust. The effect of space velocity and various reactant concentrations on the ammonia/nitrogen product distribution were studied along with the effect of these various parameters on the rate of nitric oxide removal. The pertinent chemical reactions in this system and the limitations imposed by an exhaust gas feed stream are discussed.

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ChemInform Abstract: THE DUAL STATE BEHAVIOR OF SUPPORTED NOBLE METAL CATALYSTS

Abstract: Bei der NO‐Reduktion mit Ru‐Katalysatoren traten Schwierigkeiten bei der Reproduktion der Ergebnisse auf.

Cited by 4 publications

References 1 publication

Three-Way Catalyst Response to Transients

Three-Way Catalyst Response to Transients

Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces

Catalytic Reduction of Nitric Oxide on Ruthenium

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