Thermal Response and Emission Breakthrough of Platinum Monolithic Catalytic Converters

Morgan, C. R.; Carlson, David W.; Voltz, Sterling E.

doi:10.4271/730569

Cited by 17 publications

(4 citation statements)

References 8 publications

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“…The effect of geometry will be most pronounced under conditions when complete conversion does not result. Morgan et al (1973) have discussed a phenomenon called emission breakthrough. Even though the converter is fully warmed up, some carbon monoxide can pass through unreacted.…”

Section: A C O M P a R I S O N Of V A R I O U S Cell Shapesmentioning

confidence: 99%

Mathematical models of the monolith catalytic converter: Part II. Application to automobile exhaust

1976

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Calculations are done for a series of mathematical models for a mono-Phenomena studied include axial conduction in the wall, diffusion and conduction in the gas in a transverse direction perpendicular to the flow direction, multiple steady states, and transients giving wall temperatures exceeding the adiabatic temperature.lith catalytic converter to oxidize carbon monoxide in automobile exhaust. SCOPEFor better or for worse, the use of catalytic converters to reduce automobile emissions of carbon monoxide and hydrocarbons has become a reality. Two types of catalytic converters are used for this application: packed beds and monoliths. The present study is concerned with mathematical models for the monolith converter. The simplest model which will give realistic predictions is determined, and the model calculations illustrate the important phenomena occurring in the device.Although conyiderable attention has been devoted to modeling packed-bed converters (Wei, 1975), little published information is available on modeling monolith Larry C. Young is with Amoco Production Company, Tulsa, Oklahoma.converters. Kuo (1973) developed a lumped parameter model for the monolith converter, which has been used by eight automobile and oil companies. Votruba et al. (1975) have also presented a similar model. Both these models include axial conduction in the wall. Hegedus (1974) neglects axial conduction. In a preliminary study, Young and Finlayson (1974) proposed and solved two models for the monolith, which cast some doubt on the validity of the simpler models. The essential question is whether or not to include diffusion and conduction in the fluid in a transverse direction perpendicular to the flow (and duct) axis, as did Young and Finlayson, or whether a simple lumped parameter model of this phenomenon, with specified Nusselt and Sherwood numbers,

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Section: A C O M P a R I S O N Of V A R I O U S Cell Shapesmentioning

confidence: 99%

Mathematical models of the monolith catalytic converter: Part II. Application to automobile exhaust

1976

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“…Mathematical modeling and simulation are useful in identifying the optimal designs and reducing the amount of experimentation needed to achieve this goal. Mathematical models of varying degrees of complexity (in terms of the geometric dimensionality of the model, flow modeling, washcoat diffusion modeling, and chemical kinetics modeling) have been in use over the last 2–3 decades 8–26. In particular, the one‐dimensional two‐phase (gas–solid) model26, 27 which differentiates between the gas and solid phase concentrations and temperatures has been found to describe these processes in a monolith reactor quite satisfactorily 28, 29…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

Racial differences in mammographic breast density

Carmen

Hughes

Halpern

et al. 2003

Cancer

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A one‐dimensional solid–gas model has been used to study the light‐off behavior in a reactor system. Techniques from nonlinear analysis are applied to first arrive at an analytical expression to estimate the light‐off location in the reactor. The model is then extended to estimate the thickening of the light‐off front in the vicinity of the light‐off location due to heat diffusion effects in the solid substrate. Both these results are expressed in terms of all the important operating and design variables of the monolith reactor and also the reaction specific variables such as the kinetic parameters and heats of reaction. A specific case of a three‐way catalyst (TWC) is numerically treated in detail to illustrate the application of this work. Finally, we focus on using the insight obtained from this study to suggest design guidelines to optimize the performance of automotive catalytic monolith reactors. © 2008 American Institute of Chemical Engineers AIChE J, 2008

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“…The one-piece construction offers attrition-free operation in a vibrating and pulsating atmosphere and also offers a great deal of design flexibility due to the variety of geometric configurations which can be conceived (for example, Hegedus, 1973). However, monolithic catalysts in oxidative automotive converters have been frequently plagued by thermal excursions which can deteriorate or even melt these catalysts (for example, Morgan et al, 1973). The aim of this paper is to investigate the generation and distribution of heat in catalytic monoliths during a steady state exothermic chemical reac-tion.…”

Section: Scopementioning

confidence: 99%

Temperature excursions in catalytic monoliths

Hegedus

1975

AIChE Journal

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The application of monolithic catalysts to automotive emission control has frequently been complicated by unexplained thermal degradation phenomena. This paper reports experimental and theoretical studies aimed at the understanding of how heat is generated and distributed in catalytic monoliths during an exothermal, mass transfer limited reaction.Theoretical considerations indicate that under certain operating conditions the steady state solid catalyst temperature can exceed the adiabatic reaction temperature. It is also shown that the catalyst overtemperature is influenced by the nature of the reactive species and by the geometry of the catalyst. These predictions have been verified by experiments in a novel tubular reactor. j L. LOUIS HEGEDUS General Motors Research Laboratories Warren, Michigan 48090 (0, -0,) -2 pivi = 0 or $5.00 for photocopies.

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Thermal Response and Emission Breakthrough of Platinum Monolithic Catalytic Converters

Cited by 17 publications

References 8 publications

Mathematical models of the monolith catalytic converter: Part II. Application to automobile exhaust

Mathematical models of the monolith catalytic converter: Part II. Application to automobile exhaust

Racial differences in mammographic breast density

Temperature excursions in catalytic monoliths

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