Lanthanum Lead Manganite Catalyst for Carbon Monoxide and Propylene Oxidation

Katz, Seymour; Croat, J. J.; Laukonis, Joseph V.

doi:10.1021/i360056a010

Cited by 17 publications

(5 citation statements)

References 11 publications

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“…3 Given what we have discussed about electropositive cations promoting the oxidation and stabilization of precious metals, it is not surprising that small amounts of platinum were found to be present on these LaMnO 3 -and LaCoO 3 -based samples. 118 The influence of platinum in dilute amounts on the catalytic activity of the bulk oxides of interest was noted to be quite significant, with as little as 200 ppm Pt substantially improving their tolerance to sulfur poisoning, 7 but the nature of contaminant Pt was not immediately clear. X-ray photoelectron studies of Pt-containing La 0.7 Pb 0.3 MnO 3 , reported by researchers at Bell Laboratories, revealed the presence of Pt 4+ , and motivated the comparison of a bulk oxide containing Pt 4+ ions with a conventional supported metal.…”

Section: Perspectivementioning

confidence: 99%

Chemistry of precious metal oxides relevant to heterogeneous catalysis

2013

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The platinum group metals (PGMs) are widely employed as catalysts, especially for the mitigation of automotive exhaust pollutants. The low natural abundance of PGMs and increasing demand from the expanding automotive sector necessitates strategies to improve the efficiency of PGM use. Conventional catalysts typically consist of PGM nanoparticles dispersed on high surface area oxide supports. However, high PGM loadings must be used to counter sintering, ablation, and deactivation of the catalyst such that sufficient activity is maintained over the operating lifetime. An appealing strategy for reducing metal loading is the substitution of PGM ions into oxide hosts: the use of single atoms (ions) as catalytic active sites represents a highly atom-efficient alternative to the use of nanoparticles. This review addresses the crystal chemistry and reactivity of oxide compounds of precious metals that are, or could be relevant to developing an understanding of the role of precious metal ions in heterogeneous catalysis. We review the chemical conditions that facilitate stabilization of the notoriously oxophobic precious metals in oxide environments, and survey complex oxide hosts that have proven to be amenable to reversible redox cycling of PGMs.

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Section: Perspectivementioning

confidence: 99%

Chemistry of precious metal oxides relevant to heterogeneous catalysis

2013

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“…studies have revealed that co&4 is a more active catalyst for these reactions than are the other 3-d metal oxides (Yao, 1975;Dwyer, 1972;Shelef et al, 1968; Hofer et al, 1M, Katz et al, 1975;Krylov, 1970;Boreskov, 1973). Its activity h a been found to be comparable to that of the noble metals, such as Pt and Pd.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of CO oxidation over Co₃O₄/γ‐Al₂O₃. Part I: Steady state

Perti¹,

Kabel²

1985

AIChE Journal

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Steady state experiments and their interpretation were performed to explore the kinetics of CO oxidation over a supported c0@4 catalyst. The rate of reaction was found to depend on temperature and the partial pressure of oxygen but not on the partial pressure of carbon monoxide. It is shown that catalyst dynamics must be accounted for to achieve real understanding. SCOPEAmong the transition metal oxides, cobalt oxide (Co304) is one of the most active catalysts for carbon monoxide oxidation. The catalytic surface is known to play an important role, yet there is no consensus in the literature regarding the reaction mechanism. The only previous extensive study of this reaction system was by Yao (1974), who emphasized the comparison of activities of cobalt oxide catalysts prepared by various methods. She showed that the catalytic activity of C0304 for CO oxidation could even compare favorably with the noble metals, but her rate data were not sufficiently definitive to attempt any mechanistic interpretations. The broad goal of the three papers that comprise this series is to elucidate the mechanistic character of oxidation-reduction catalysis by metal oxides. This first paper deals with conventional steady state experimentation. A fixed-bed reactor was used to study the dependence of conversion (and thence reaction rate) on flow rate, temperature, CO and 0 2 partial pressures, and catalyst characteristics. The interpretation of the steady state results enhances understanding, but more importantly it establishes a basis for comparison of the results of the dynamic studies described in Parts I1 and 111.

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“…However, microwave irradiation enhances the diffusion of some species (Fe 3+ , in this case) selectively. There remain serious discussions about enhancement of solidstate diffusion by microwave irradiation, including whether it exists 12,13 or does not exist, 14 but from the result of this study, it seems to exist.…”

Section: Discussionmentioning

confidence: 75%

Microwave Synthesis of Yttrium Iron Garnet Powder

Kimura

Takizawa

Uheda

et al. 1998

Journal of the American Ceramic Society

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A 28 GHz microwave heating method was used to react an Fe2O3+ Y2O3 powder mixture to form yttrium iron garnet (YIG, Y3Fe5O12) powder. The minimum temperature to form YIG was lower than the conventional (external) heating method. YIG began to form after only 70 s of irradiation, which means that the solid‐state reaction proceeded very rapidly. The amounts of byproducts were controlled by the starting composition and by the Y2O3 particle size. The resultant YIG particle size also was controlled by the Y2O3 particle size.

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Lanthanum Lead Manganite Catalyst for Carbon Monoxide and Propylene Oxidation

Cited by 17 publications

References 11 publications

Chemistry of precious metal oxides relevant to heterogeneous catalysis

Chemistry of precious metal oxides relevant to heterogeneous catalysis

Kinetics of CO oxidation over Co₃O₄/γ‐Al₂O₃. Part I: Steady state

Microwave Synthesis of Yttrium Iron Garnet Powder

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Lanthanum Lead Manganite Catalyst for Carbon Monoxide and Propylene Oxidation

Cited by 17 publications

References 11 publications

Chemistry of precious metal oxides relevant to heterogeneous catalysis

Chemistry of precious metal oxides relevant to heterogeneous catalysis

Kinetics of CO oxidation over Co3O4/γ‐Al2O3. Part I: Steady state

Microwave Synthesis of Yttrium Iron Garnet Powder

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Kinetics of CO oxidation over Co₃O₄/γ‐Al₂O₃. Part I: Steady state