Steady-state and dynamic hysteresis effects during lean co-oxidation of CO and C3H6 over Pt/Al2O3 monolithic catalyst

Raj, Richa; Harold, Michael P.; Balakotaiah, Vemuri

doi:10.1016/j.cej.2015.06.057

Cited by 47 publications

(47 citation statements)

References 30 publications

(97 reference statements)

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“…As they are validated in a previous publication [6], we do not modify them here (except for adjusting the rates for different amounts of Pt loading).…”

Section: Kinetic Modelmentioning

confidence: 97%

“…Raj et al [6] showed that the second inhibition term is needed in the rate expressions of CO and ‫ܥ‬ ଷ ‫ܪ‬ oxidations to account for mutual inhibition. These global rate expressions are empirical and are based on fitting the experimental light-off curves at different concentrations.…”

Section: Kinetic Modelmentioning

confidence: 99%

“…During co-oxidation of CO and ‫ܥ‬ ଷ ‫ܪ‬ , mutual inhibiting terms are also present and the corresponding rate expressions are [6] …”

Section: Kinetic Modelmentioning

confidence: 99%

“…Khosravi et al [5] investigated the oxidation of carbon monoxide, nitrogen monoxide and propene and the reduction of nitrogen monoxide by propene over two diesel oxidation catalysts. A more recent study by Raj et al [6] examined steady-state and dynamic hysteresis effects during co-oxidation of CO and C 3 H 6 on Pt/Al 2 O 3 .…”

Section: Introduction and Literature Reviewmentioning

confidence: 98%

“…In section 6 we determine bifurcation features when all the three species are present in the 6 feed. The last section summarizes the main results and their possible application to the design and operation of DOCs.…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

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Bifurcation features of mixtures containing CO and hydrocarbons in diesel oxidation catalyst

Dadi

Luss

Balakotaiah

2016

Chemical Engineering Journal

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A model of a monolith reactor with radial gradients in the washcoat is used to study the ignition-extinction of pure CO, C 2 H 6 and C 3 H 6 and of their mixtures on a Pt/Al 2 O 3 diesel oxidation catalyst. The ignition temperature of the individual species oxidation increases upon an increase in feed concentration of either CO or C 3 H 6 and decreases upon an increase in feed concentration of C 2 H 6 . This is because CO, C 3 H 6 have negative order kinetics and C 2 H 6 has positive order kinetics. We determine the steady-state hysteresis behavior of conversion versus feed temperature during co-oxidation of CO and hydrocarbons (C 3 H 6 , C 2 H 6 ). A single S-shaped bifurcation diagram of conversion versus inlet temperature is obtained during the co-oxidation of all feed mixtures of CO and C 3 H 6 because the activation energies of CO and C 3 H 6 are close to each other. The presence of CO in the feed inhibits the oxidation of propylene during the cooxidation of CO and C 3 H 6 . In contrast, the ignition temperatures of pure CO and pure C 2 H 6 are much different and CO ignites at a much lower temperature than C 2 H 6 A double-S shaped 2 bifurcation diagram is obtained when hysteresis exists for both CO and C 2 H 6 during the cooxidation. The oxidation of CO present in the feed increases the catalyst temperature and this reduces the C 2 H 6 ignition temperature. The separated ignition is transformed to a simultaneous ignition when the CO concentration in the feed is sufficiently high. We determine the boundary in the parameter space of feed compositions and other operating conditions that separate the simultaneous and separate ignition. The application of this result for the design of DOCs for treating exhaust gases at lower inlet temperatures is discussed.

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“…As they are validated in a previous publication [6], we do not modify them here (except for adjusting the rates for different amounts of Pt loading).…”

Section: Kinetic Modelmentioning

confidence: 97%

Section: Kinetic Modelmentioning

confidence: 99%

“…During co-oxidation of CO and ‫ܥ‬ ଷ ‫ܪ‬ , mutual inhibiting terms are also present and the corresponding rate expressions are [6] …”

Section: Kinetic Modelmentioning

confidence: 99%

Section: Introduction and Literature Reviewmentioning

confidence: 98%

Section: Introduction and Literature Reviewmentioning

confidence: 99%

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Bifurcation features of mixtures containing CO and hydrocarbons in diesel oxidation catalyst

Dadi

Luss

Balakotaiah

2016

Chemical Engineering Journal

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PdCu Alloy Catalyst for Inhibition‐free, Low‐temperature CO Oxidation

Song,

Svadlenak,

Bathena

et al. 2023

ChemCatChem

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Designing robust catalysts for low‐temperature oxidation is pertinent to the development of advanced combustion engines to meet increasingly stringent emissions limitations. Oxidation of CO, hydrocarbon and NO pollutants over platinum‐group catalysts suffer from strong inhibition due to their competitive adsorption, while coinage metals are generally slow at activating O2. Through computational screening we discovered a PdCu alloy catalyst that completely oxidizes CO below 150 °C without inhibition by NO, propylene or water. This is attributed primarily to geometric effects and the presence of CO bound to Pd sites within the Cu‐rich surface of the PdCu alloy. We demonstrate that the novel PdCu catalyst can be used in tandem with a PtPd catalyst to achieve sequential, inhibition‐free, complete oxidation of CO in a two‐bed system, while also achieving 50% NO conversion below 120 °C. Moreover, neither water nor propylene adversely affect the low temperature CO oxidation activity.

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Self‐sustained oscillations within the temperature hysteresis in CO oxidation over Pd: Mathematical model of a cascade of continuous stirred‐tank reactors

Lashina

Slavinskaya

Чумакова

et al. 2019

Int J of Chemical Kinetics

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The results of temperature‐programmed reaction experimental studies and mathematical modeling of self‐sustained oscillations within an inverse temperature hysteresis in CO oxidation over Pd catalyst are presented. The experimental data demonstrate the influence of the reaction medium on the catalyst activity under reaction conditions. Under oxygen excess in the feeding gas mixture and high temperature, the defects appeared on the initially flat surface of metallic palladium due to deep oxidation of palladium (three‐dimensional PdO nanoparticles were observed). The palladium oxide reduced under cooling of the catalytic system, and the catalyst surface became flat again. To take into account these variations of the palladium surface structure, we consider the piecewise‐constant dependence of the rate constant of some reaction step on the concentrations of oxygen species, namely, the dissolved oxygen or oxide in the palladium bulk. The proposed model of the process in the cascade of continuous stirred‐tank reactors that account for these dependences qualitatively describes the inverse temperature hysteresis as well as the oscillatory dynamics within the hysteresis loop which were obtained experimentally.

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Steady-state and dynamic hysteresis effects during lean co-oxidation of CO and C3H6 over Pt/Al2O3 monolithic catalyst

Cited by 47 publications

References 30 publications

Bifurcation features of mixtures containing CO and hydrocarbons in diesel oxidation catalyst

Bifurcation features of mixtures containing CO and hydrocarbons in diesel oxidation catalyst

PdCu Alloy Catalyst for Inhibition‐free, Low‐temperature CO Oxidation

Self‐sustained oscillations within the temperature hysteresis in CO oxidation over Pd: Mathematical model of a cascade of continuous stirred‐tank reactors

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