Multiple steady states in an isothermal, integral reactor: the catalytic oxidation of carbon monoxide over platinum--alumina
TL;DR: In this article, stable isothermal multiplicities were observed during carbon monoxide oxidation in an integral reactor, filled with alumina supported platinum catalysts, in the conversion-temperature, conversion-inlet carbon dioxide concentration and conversion-mass flow rate domains.
Abstract: Stable isothermal multiplicities were observed during carbon monoxide oxidation in an integral reactor, filled with alumina supported platinum catalysts. The multiplicities were investigated in the conversion-temperature, conversion-inlet carbon monoxide concentration and conversion-mass flow rate domains. The region of multiplicities was found to widen significantly upon catalyst aging which enhanced the pellets' diffusive resistances. Several intermediate stable steady states were found between the highest and lowest steady states, both experimentally and theoretically. All the above phenomena could be well interpreted by the interactions of the kinetics of carbon monoxide oxidation with intrapellet diffusion resistances.
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27 Oct 2011
TL;DR: The diesel oxidation catalyst (DOC) has been part of diesel exhaust systems since regulations were introduced to limit the amount of harmful emissions released to the environment from diesel engines as discussed by the authors, while active hydrocarbon oxidation can also be used to generate exotherms required for downstream components.
Abstract: The diesel oxidation catalyst (DOC) has been part of diesel exhaust systems since regulations were introduced to limit the amount of harmful emissions released to the environment from diesel engines. The DOC primary functions are oxidation of CO, unburned hydrocarbons, and NO, while active hydrocarbon oxidation can also be used to generate exotherms required for downstream components. This review will describe work that has attempted to understand the reactions, both desired and undesired, that occur over the catalyst. First, the history, configuration, and components of the DOC will be discussed, followed by in-depth coverage of the fundamental reactions that occur over a DOC, including reaction mechanisms, reaction inhibition, and other reactivity effects. Finally, DOC deactivation mechanisms and their effects on the DOC are described. While there is a lot of research literature regarding Pt- and Pd-based catalysts for many different reaction schemes, this review tries to highlight work most relevant to...
326 citations
Cites background from "Multiple steady states in an isothe..."
...Within the hysteresis boundaries, multiple steady-states can be achieved, as noted by Hegedus and Baron (171), Bar et al. (160), and Salomons et al. (136), in attempts to model the hysteresis effect for CO oxidation over automotive catalysts during temperature and inlet CO concentration ramps....
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...However, when water was added to the reactant mixture, these multiple steady states would not form, which the researchers suggested was caused by a decrease in the equilibrium constant for CO chemisorption (171)....
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...Within the hysteresis boundaries, multiple steady-states can be achieved, as noted by Hegedus and Baron (171), Bar et al....
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TL;DR: In this paper, the authors present a theoretical explanation for carbon monoxide on platinum catalytic catalytic reactions, which poses difficulties and challenges to both the experimentalist and the theoretician, due to the frequent observations of hysteresis, associated with steady-state multiplicity, and self-sustained oscillations in the reaction.
Abstract: Although the oxidation of carbon monoxide on platinum is one of the oldest known catalytic reactions and one of the most thoroughly studied, it continues to pose difficulties and challenges to both the experimentalist and the theoretician. For the most part, these are due to the frequent observations of hysteresis, associated with steady-state multiplicity, and self-sustained oscillations in the reaction and to the fact that no generally accepted theoretical explanation for them is at hand. even though a large number of studies have addressed the subject.
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TL;DR: In this article, active hydrophobic-supported Pt catalysts were synthesized for VOC deep oxidation at low temperature (less than 200°C) to destroy VOC at lower temperature due to less energy consumption.
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