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S. De Rossi

Bio: S. De Rossi is an academic researcher from Sapienza University of Rome. The author has contributed to research in topics: Catalysis & Dehydrogenation. The author has an hindex of 19, co-authored 34 publications receiving 1479 citations.

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TL;DR: In this article, the authors investigated catalytic methane combustion and CO oxidation over AFeO3 (A=La, Nd, Sm) and LaFe1−xMgxO3(x=0.4, 0.5) perovskites prepared by citrate method.
Abstract: Catalytic methane combustion and CO oxidation were investigated over AFeO3 (A=La, Nd, Sm) and LaFe1−xMgxO3 (x=0.1, 0.2, 0.3, 0.4, 0.5) perovskites prepared by citrate method and calcined at 1073 K. The catalysts were characterized by X-ray diffraction (XRD). Redox properties and the content of Fe4+ were derived from temperature programmed reduction (TPR). Specific surface areas (SA) of perovskites were in 2.3–9.7 m2 g−1 range. XRD analysis showed that LaFeO3, NdFeO3, SmFeO3 and LaFe1−xMgxO3 (x·0.3) are single phase perovskite-type oxides. Traces of La2O3, in addition to the perovskite phase, were detected in the LaFe1−xMgxO3 catalysts with x=0.4 and 0.5. TPR gave evidence of the presence in AFeO3 of a very small fraction of Fe4+ which reduces to Fe3+. The fraction of Fe4+ in the LaFe1−xMgxO3 samples increased with increasing magnesium content up to x=0.2, then it remained nearly constant. Catalytic activity tests showed that all samples gave methane and CO complete conversion with 100% selectivity to CO2 below 973 and 773 K, respectively. For the AFeO3 materials the order of activity towards methane combustion is La>Nd>Sm, whereas the activity, per unit SA, of the LaFe1−xMgxO3 catalysts decreases with the amount of Mg at least for the catalysts showing a single perovskite phase (x=0.3). Concerning the CO oxidation, the order of activity for the AFeO3 materials is Nd>La>Sm, while the activity (per unit SA) of the LaFe1−xMgxO3 catalysts decreases at high magnesium content.

221 citations

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TL;DR: In this paper, the role of the adsorbed oxygen has been studied by examining the variations of the electrical conductivity of the catalysts during the processes of oxygen adsorption-desorption.
Abstract: The catalytic combustion of some volatile organic compounds (VOCs) has been investigated over LaMnO3 and LaCoO3 perovskite-type oxides. Redox titration has shown that cobalt is present in LaCoO3 exclusively in the 3+ oxidation state whereas LaMnO3 contains considerable amount of Mn4+ (35%) in addition to Mn3+. VOCs reactivity towards total oxidation follows the trend: acetone > isopropanol > benzene. The oxidation of isopropanol occurs through the formation of acetone in the homogeneous reaction. The increase of the oxygen partial pressure is beneficial for total oxidation of acetone. The adsorptive properties of the catalysts towards the VOCs and H2 have been examined by means of temperature programmed desorption. The LaMnO3 surface is the most reactive to the adsorption of VOCs and H2. The role of the adsorbed oxygen has been studied by examining the variations of the electrical conductivity of the catalysts during the processes of oxygen adsorption–desorption.

197 citations

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TL;DR: In this paper, tetragonal ZrO2-supported La, Mn oxide catalysts with different loading (0.7, 2, 4, 6, 12, and 16 wt% as LaMnO3) were prepared by impregnation of Tetragonal zirconia with equimolar amounts of La and Mn citrate precursors and calcination at 1073 K.

117 citations

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TL;DR: In this paper, the surface area determination, X-ray diffraction, XRD, XPS, XAS, diffuse optical reflectance, Raman spectroscopy and chemical analysis of Zirconia supported tungsten oxide catalysts were performed.
Abstract: Zirconia supported tungsten oxide catalysts (tungsten content up to 337 wt%) were prepared by equilibrium adsorption and impregnation in acid (pH 27) and basic (pH 10) conditions using hydrous zirconium oxide After thermal treatment at 1073 K in air, the catalysts were characterized by surface area determination, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), diffuse optical reflectance, Raman spectroscopy and chemical analysis The results show that tungsten is present as a dispersed phase and as monoclinic WO3 crystallites The density of tungsten in a dispersed form was estimated as about 5 atoms nm−2 Leaching treatments with ammonia revealed that only a fraction of the dispersed tungsten interacts directly with the support surface The interacting species, in the form of small clusters, as revealed by EXAFS and Raman spectroscopy, control the ZrO2 surface area and are responsible for the structural changes in the support Subsequent thermal treatment up to 1073 K in air leaves them unchanged

99 citations

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TL;DR: In this paper, structural, redox and catalytic deep oxidation properties of LaAl 1− x Mn x O 3 (x = 0.0, 0.05,0.1, 1.0) solid solutions prepared by the citrate method and calcined at 1073 K were investigated.
Abstract: Structural, redox and catalytic deep oxidation properties of LaAl 1− x Mn x O 3 ( x =0.0, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0) solid solutions prepared by the citrate method and calcined at 1073 K were investigated. XRD analysis showed that all the LaAl 1− x Mn x O 3 samples are single phase perovskite-type solid solutions. Particle sizes and surface areas (SA) are in the 280–1180 A and 4–33 m 2 g −1 ranges, respectively. Redox properties and the content of Mn 4+ were derived from temperature programmed reduction (TPR) with H 2 . Two reduction steps are observed by TPR for pure LaMnO 3 , the first attributed to the reduction of Mn 4+ to Mn 3+ and the second due to complete reduction of Mn 3+ to Mn 2+ . The presence of Al in the LaAl 1− x Mn x O 3 solid solutions produces a strong promoting effect on the Mn 4+ →Mn 3+ reducibility and inhibits the further reduction to Mn 2+ . Both for methane combustion and CO oxidation all Mn-containing perovskites are much more active than LaAlO 3 , so pointing to the essential role of the transition metal ion in developing highly active catalysts. Partial dilution with Al appears to enhance the specific activity of Mn sites for methane combustion.

96 citations


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TL;DR: The study compares different catalysts in terms of the reaction mechanism and deactivation pathways and catalytic performance, as dehydrogenation for the production of light olefins has become extremely relevant.
Abstract: A study is conducted to demonstrate catalytic dehydrogenation of light alkanes on metals and metal oxides. The study provides a complete overview of the materials used to catalyze this reaction, as dehydrogenation for the production of light olefins has become extremely relevant. Relevant factors, such as the specific nature of the active sites, as well as the effect of support, promoters, and reaction feed on catalyst performance and lifetime, are discussed for each catalytic Material. The study compares different catalysts in terms of the reaction mechanism and deactivation pathways and catalytic performance. The duration of the dehydrogenation step depends on the heat content of the catalyst bed, which decreases rapidly due to the endothermic nature of the reaction. Part of the heat required for the reaction is introduced to the reactors by preheating the reaction feed, additional heat being provided by adjacent reactors that are regenerating the coked catalysts.

1,306 citations

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TL;DR: The available technologies for the abatement of phenol from water and gaseous streams are briefly reviewed, and the recent advancements summarized.

1,175 citations

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TL;DR: 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 and addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions.
Abstract: 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.

1,074 citations

Journal ArticleDOI
TL;DR: In this article, the kinetics and mechanism of CO oxidation on single and mixed oxides are examined, alongside the catalyst structures, in a review of the literature on carbon monoxide over oxide catalysts.
Abstract: 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

821 citations

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TL;DR: This work focuses on the surface chemistry and spectroscopy of chromium in inorganic oxides and the mechanics of hydrogenation-dehydrogenation reactions.
Abstract: Focuses on the surface chemistry and spectroscopy of chromium in inorganic oxides. Characterization of the molecular structures of chromium; Mechanics of hydrogenation-dehydrogenation reactions; Mobility and reactivity on oxidic surfaces.

728 citations