Alessandra Primavera

Bio: Alessandra Primavera is an academic researcher from University of Udine. The author has contributed to research in topics: Catalysis & Cubic zirconia. The author has an hindex of 7, co-authored 10 publications receiving 508 citations.

Catalytic combustion of hydrocarbons with Mn and Cu-doped ceria–zirconia solid solutions

Abstract: The catalytic activity of a series of CeO2–ZrO2 mixed oxides in the total oxidation of methane and light hydrocarbons has been investigated. The influence of dopants like Mn and Cu has also been studied. It is shown that both MnOx and CuO at low loading dissolve within the ceria–zirconia lattice. This strongly influences the redox behaviour of the catalysts by promoting low-temperature reduction of Ce4+. In addition, the ternary oxides show better stability to repeated redox cycles, which is attributed to the presence of ZrO2. The catalytic activity of pure CeO2 is also enhanced in the presence of ZrO2, reaching a maximum with Ce0.92Zr0.08O2; a further promotion of activity is observed with the introduction of MnOx and CuO dissolved into CeO2–ZrO2 lattice.

The effect of water in the low-temperature catalytic oxidation of hydrogen sulfide to sulfur over activated carbon

Abstract: This study investigates the use of low-temperature catalytic oxidation for the removal of H 2 S from tail gases originating from geothermal plants, with special focus on the effect of water on the overall performance of the activated carbon catalyst. It is shown that water strongly influences the reaction rate and the total amount of sulfur that can be adsorbed on the catalyst prior to regeneration. It is suggested that the reaction takes place in a thin water layer, inside the carbon pores, from the reaction of dissolved H 2 S with chemisorbed oxygen.

Wet oxidation of acetic acid catalyzed by doped ceria

Abstract: A series of ceria-containing mixed oxides has been prepared and utilized as catalysts in the oxidation of acetic acid in water. The incorporation of even relatively small amounts of ZrO 2 and MnO x or CuO into the fluorite lattice of CeO 2 strongly enhances the redox properties of the material with a consequent promotion of the oxidation activity. The best results are obtained with the ternary mixed-oxides CeO 2 -ZrO 2 -CuO and CeO 2 -ZrO 2 -MnO x which benefit from a synergetic interaction between CeO 2 (whose properties are already modified by the presence of Zr) and CuO or MnO x . Analysis of metal ion concentration in the effluents after reaction indicates also a high stability of the mixed-oxide catalysts under the conditions employed.

Acid–base properties and catalytic activity of nanophase ceria–zirconia catalysts for 4-methylpentan-2-ol dehydration

Abstract: The room-temperature high energy ball-milling technique was used to prepare nanophase Ce1-xZrxO2 (x=0; 0.2; 0.5; 0.8; 1) catalysts. The acid–base properties of these catalysts were investigated by means of adsorption microcalorimetry, using NH3 and CO2 as probe molecules. The catalytic activity for 4-methylpentan-2-ol dehydration was tested at atmospheric pressure in a fixed-bed flow microreactor. The inclusion of increasingly high contents of zirconium into the ceria lattice has a complex influence on the acidity and basicity of the pure parent oxide, in terms of both number and strength of the sites. A maximum in 1-alkene selectivity is observed for the ceria-rich catalyst and a minimum for the zirconia-rich sample. Catalytic results are correlated with the acid–base properties and can be interpreted in the light of the mechanism formerly proposed for zirconia, ceria and lanthania. Surface conditioning of the zirconia-rich catalyst occurs during the run, resulting in a remarkable variation of selectivity.

Structural Characterization of Ceria–zirconia Powder Catalysts Prepared by High-energy Mechanical Milling: A Neutron Diffraction Study

Abstract: Neutron diffraction measurements were carried out on samples of CeO2–ZrO2 powder catalysts prepared by high-energy mechanical milling. The formation of solid solution was evidenced across the entire composition range examined. Quantitative phase evaluation by the Rietveld method indicated formation of tetragonal structure for low CeO2 content, whereas cubic solid solutions were the stable form at high CeO2 loading. In addition, a pseudocubic or tetragonal t″ cell with axial ratio of unity and with internal deformation of the oxygen sublattice was observed at intermediate composition (50 mol% CeO2). Thermal annealing up to 1000 °C showed expansion of the unit cell parameters; an increase in the degree of tetragonality at the expense of cubic and monoclinic phase was observed for composition CexZr1−xO2 (x < 0.5).

Automotive catalytic converters: current status and some perspectives

Abstract: Automotive three-way catalysts (TWCs) have represented over the last 25 years one of the most successful stories in the development of catalysts. The aim of this paper is to illustrate the technology for abatement of exhaust emissions by analysing the current understanding of TWCs, the specific role of the various components, the achievements and the limitations. The challenges in the development of new automotive catalysts, which can meet future highly demanding pollution abatement requirements, are also discussed.

The utilization of ceria in industrial catalysis

Abstract: The main applications of cerium dioxide in industrial catalysis are reviewed, with particular attention to the role played by ceria. The main uses of CeO2 are connected to depollution of noxious compounds from gaseous streams originating from industrial productions and from automobiles (de-SOx in FCC processes; treatment of emissions from spark-ignited and diesel engines), although ceria is also a key component of catalyst formulation for the dehydrogenation of ethylbenzene to styrene. Recent advances in the application of ceria for the removal of organic compound from wastewater through oxidation (catalytic wet oxidation CWO) are also reviewed. # 1999 Elsevier Science B.V. All rights reserved.

Catalysts for combustion of methane and lower alkanes

Abstract: The important greenhouse effect of methane (more than an order of magnitude greater than CO2) makes it essential to eliminate/control the methane emission from natural gas engines/power plants and petroleum industries. Catalytic combustion of methane is favored over homogeneous combustion, because the former greatly facilitates the oxidative destruction of methane. Moreover, use of catalysts for methane combustion in gas-turbines affords lower working temperatures (as compared to gas-fired turbines) and thermodynamically limits NOx (which is an extremely harmful environmental pollutant) emission. A large amount of work has been undertaken to develop catalysts both for controlling methane emission as well as for generating power in high temperature natural gas-turbines. This review will address the different issues related to the variety of catalysts which have been employed for methane/lower alkane combustion. Although all the related important aspects of the combustion catalysts will be addressed, greater emphasis will be placed on recent work in this field.

Heterogeneous catalytic wet air oxidation of refractory organic pollutants in industrial wastewaters: a review.

Abstract: Catalytic wet air oxidation (CWAO) is one of the most economical and environmental-friendly advanced oxidation process. It makes a promising technology for the treatment of refractory organic pollutants in industrial wastewaters. Various heterogeneous catalysts including noble metals and metal oxides have been extensively studied to enhance the efficiency of CWAO. The present review is concerned about the literatures published in this regard. Phenolics, carboxylic acids, and nitrogen-containing compounds were taken as model pollutants in most cases, and noble metals such as Ru, Rh, Pd, Ir, and Pt as well as oxides of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, and Ce were applied as heterogeneous catalysts. Reports on their characterization and catalytic performances for the CWAO of aqueous pollutants are reviewed. Discussions are also made on the reaction mechanisms and kinetics proposed for heterogeneous CWAO and also on the typical catalyst deactivations in heterogeneous CWAO, i.e. carbonaceous deposits and metal leaching.

Wet Oxidation and Catalytic Wet Oxidation

Abstract: This review article explores three major aspects of the wet oxidation (WO) and catalytic wet oxidation (CWO) processes (with the major focus being on WO and CWO, using air or oxygen as an oxidant). These aspects are (a) the fundamental chemistry of WO/CWO; (b) important aspects of catalysts, with regard to the CWO process; and (c) engineering aspects of the WO/CWO process. The applications of WO and CWO technology to treat industrial wastewater clearly illustrate the potential of these processes for treating wastewater from a wide number of industries. WO/CWO is a fertile area of research with significant scope for further research and innovation, particularly in the areas of catalyst development, the understanding of catalytic mechanisms, and the fundamental chemistry that occurs during WO/CWO. Selected examples of findings to date are discussed in this review.