II. Structure of Perovskites 1982 A. Crystal Structure 1982 B. Nonstoichiometry in Perovskites 1983 1. Oxygen Nonstoichiometry 1983 2. Cation Nonstoichiometry 1984 C. Physical Properties 1985 D. Adsorption Properties 1986 1. CO and NO Adsorption 1986 2. Oxygen Adsorption 1987 E. Specific Surface and Porosity 1987 F. Thermal Stability in a Reducing Atmosphere 1989 III. Acid−Base and Redox Properties 1990 A. Acidity and Basicity 1990 B. Redox Processes 1991 1. Kinetics and Mechanisms 1992 2. Reduction−Oxidation Cycles 1993 C. Ion Mobility 1993 1. Oxygen Transport 1993 2. Cation Transport 1994 IV. Heterogeneous Catalysis 1995 A. Oxidation Reactions 1995 1. CO Oxidation 1995 2. Oxidation of Hydrocarbons 1996 B. Pollution Abatement 2001 1. NOx Decomposition 2001 2. Exhaust Treatment 2002 3. Stability 2004 C. Hydrogenation and Hydrogenolysis Reactions 2004 1. Hydrogenation of Carbon Oxides 2004 2. Hydrogenation and Hydrogenolysis Reactions 2006

Chemical structures and performance of perovskite oxides.

It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.

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Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

Oxidation into CO2 is a major solution to CO abatement in air depollution treatments. The development of catalytic converters led to an extraordinary high number of publications on metal catalysts during the last fifty years. Due to the increasing price of noble metals and to remarkable progresses in oxide syntheses, catalytic oxidation of carbon monoxide over oxide catalysts has recently gained in interest, even if some oxides are known to present remarkable activity since the beginning of the 20th century. In this Review, the kinetics and mechanism of CO oxidation on single and mixed oxides are examined, alongside the catalyst structures

Catalytic Oxidation of Carbon Monoxide over Transition Metal Oxides

An overview is given on the ongoing activities in the area of the decomposition of nitrous oxide, N2O, over solid catalysts. These catalysts include metals, pure and mixed oxides, supported as well as unsupported, and zeolitic systems. The review covers aspects of the reaction mechanism and kinetics, focusing on the role of surface oxygen, the inhibition by molecular oxygen, water and other species, poisoning phenomena and practical developments.

Heterogeneous catalytic decomposition of nitrous oxide

Perovskites as substitutes of noble metals for heterogeneous catalysis: dream or reality.

The catalytic activities of perovskite-type mixed oxides (LnBO3 and Ln0.8Sr0.2CoO3, Ln=rare-earth (lanthanoid) elements, B=3d transition metals) for the oxidation of propane and methanol have been studied comparatively. It has been found that the catalytic activities of LnBO3 were principally determined by the B-site elements and were similar to those of the corresponding oxides of the B-site elements. The roles of the rare-earth ions of the A-site were secondary as long as they were trivalent. Upon the partial replacement of Ln3+ by Sr2+, the catalytic activities of LnCoO3 increased several times, the magnitude of the increase being similar among all the rare-earth ions. These results demonstrate that the kind and the valence of a B-site metal are of primary importance for the control of the catalytic activity for oxidation, almost regardless of the kind of trivalent rare-earth elements at the A-site.

Catalytic Properties of Perovskite-Type Mixed Oxides (ABO3) Consisting of Rare Earth and 3d Transition Metals. The Roles of the A- and B-Site Ions

Catalytic properties of La1 − xA′xFeO3(A′ = Sr,Ce) and La1 − xCexCoO3

Catalytic properties of La1−xA′xMnO3 (A′ = Sr, Ce, Hf)

The direct decomposition of nitrogen monoxide (NO) to N2 and O2 was carried out over valency-controlled La2−xA′xCu1−yB′yO4 (A′ = Sr, Ba, Ca, Ce; B′ = Zr, Al) mixed oxide catalysts with a K2NiF4-type structure. The catalysts were characterized by XRD, XPS, redox titration, and oxygen TPD. It was confirmed by XPS that the surface and bulk compositions generally agreed and by redox titration that the average oxidation number (AON) of copper varied widely from 1.60 to 2.30. XPS showed that the valency of surface copper agreed with AON for AON ≤ 2, while it was in the Cu2+ state for AON > 2.0. The amounts of oxygen desorbed in TPD and the oxygen nonstoichiometry of La2−xSrxCuO4 increased with x in parallel. The catalytic activity for NO decomposition showed a maximum at x = 0.4—0.5, and a good correlation was found between the catalytic activity and AON for all of the catalysts tested. The decomposition of dinitrogen oxide (N2O) was also carried out for La2−xSrxCuO4 for a comparison. Based on the much slower r...

Catalytic Decomposition of Nitrogen Monoxide over Valency-Controlled La2CuO4-Based Mixed Oxides.

A series of La2−xSrxNiO4 catalysts (x=0–1.0) with a K2NiF4-type structure were prepared, and the average oxidation number of the Ni ion and the stoichiometry of the oxygen in the catalysts were measured. We also investigated the relationships between the reactivity of the catalysts and their catalytic activity for oxidation. The average oxidation number of the Ni ion increased monotonously from 2.32 (x=0) to 2.90 (x=1.0) upon the Sr substitution, and the composition changed with the x value from oxygen-excess (x=0–0.2) to oxygen-deficient (x=0.6–1.0), via a stoichiometric composition at x=0.4. In the range of x=0–0.2 (oxygen excess), the desorption peaks of oxygen in TPD (temperature-programmed desorption) were observed at about 300 °C; these results were ascribable to the excess oxygen. In this range, the oxidizing power of the surface, which was measured by the reduction of the catalysts by CO, was comparatively high. For x=0.4–1.0 (stoichiometric to oxygen-deficient), the oxygen desorbed at a higher te...

Taihei Nitadori

Papers

Catalytic Properties of Perovskite-Type Mixed Oxides (ABO3) Consisting of Rare Earth and 3d Transition Metals. The Roles of the A- and B-Site Ions

Catalytic properties of La1 − xA′xFeO3(A′ = Sr,Ce) and La1 − xCexCoO3

Catalytic properties of La1−xA′xMnO3 (A′ = Sr, Ce, Hf)

Catalytic Decomposition of Nitrogen Monoxide over Valency-Controlled La2CuO4-Based Mixed Oxides.

The Valence Control and Catalytic Properties of La2−xSrxNiO4