Ilenia Rossetti

University of Milan, Milano, Lombardy, Italy

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Publications (61)115.79 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work the performance of CaO-doped Ni/ZrO2 catalysts in ethanol steam reforming was studied. The addition of CaO did not affect the morphology or the crystalline structure of the support. On the contrary, Ni reducibility markedly increased. Moreover, the Lewis acidity of zirconia gradually decreased as the CaO content increased, thus inhibiting coke deposition and improving the carbon balance. The addition of a basic oxide helps to prevent some of the side reactions responsible for coke formation and deposition, that can gradually deactivate the catalyst.
    Applied Catalysis B: Environmental. 01/2014; s 150–151:12–20.
  • Applied Catalysis A: General. 01/2014; 477:42–53.
  • International Journal of Hydrogen Energy 01/2014; 39(9):4252–4258. · 3.55 Impact Factor
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    ABSTRACT: Methods and models describing oxygen diffusion and desorption in oxides have been developed for slightly defective and well crystallised bulky materials. Does nanostructuring change the mechanism of oxygen mobility? In such a case, models should be properly checked and adapted to take into account new material properties. In order to do so, temperature programmed oxygen desorption and thermogravimetric analysis, either in isothermal or ramp mode, have been used to investigate some nanostructured La1-xAxMnO3±δ samples (A = Sr and Ce, 20-60 nm particle size) with perovskite-like structure. The experimental data have been elaborated by means of different models to define a set of kinetic parameters able to describe oxygen release properties and oxygen diffusion through the bulk. Different rate-determining steps have been identified, depending on the temperature range and oxygen depletion of the material. In particular, oxygen diffusion was shown to be rate-limiting at low temperature and at low defect concentration, whereas oxygen recombination at the surface seems to be the rate-controlling step at high temperature. However, the oxygen recombination step is characterised by an activation energy much lower than that for diffusion. In the present paper oxygen transport in nanosized materials is quantified by making use of widely diffused experimental techniques and by critically adapting to nanoparticles suitably chosen models developed for bulk materials.
    Physical Chemistry Chemical Physics 09/2013; · 3.83 Impact Factor
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    ABSTRACT: Co- and Cu-based catalysts prepared by means of a flame pyrolysis (FP) technique are proposed as possible substitutes for Ni-based catalysts, very active for the Ethanol Steam Reforming reaction, but showing poor stability towards coke formation when operating at relatively low temperature.The FP method allowed to achieve a partial incorporation of the active phase into the support, leading to high dispersion and lower reducibility, at least in the case of Co. Cu was much more reducible than both Co and Ni, but it was almost completely inactive for the reforming reaction, mainly leading to ethanol dehydrogenation to acetaldehyde. The two different supports chosen, characterized by semiconducting behaviour and different reducibility (SiO2 and TiO2), were able to differently interact with the active phase. The best results, especially at 625 and 750 °C, were achieved with 10 wt% Co/SiO2, which led to higher activity, good C balance and low CO/CO2 ratio. This was ascribed to the high initial dispersion of Co into the silica matrix, which led to available Co particles well dispersed and stable on the catalyst surface.
    International Journal of Hydrogen Energy 03/2013; 38(8):3213–3225. · 3.55 Impact Factor
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    ABSTRACT: Ni-based catalysts supported on TiO2, ZrO2 and SiO2 (in the form of mesoporous Santa Barbara Amorphous 15 (SBA-15) and amorphous dense nanoparticles), were employed in the steam reforming of glycerol. Each sample was prepared by liquid phase synthesis of the support followed by impregnation with the active phase and calcination at 800 °C or by direct synthesis through flame pyrolysis. Many techniques have been used to assess the physical chemical properties of both the fresh and spent catalysts, such as atomic absorption, N2 adsorption/desorption, XRD, SEM, TEM, temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), Micro-Raman and FTIR spectroscopy. The samples showed different textural, structural and morphological properties, as well as different reducibility and thermal resistance depending on the preparation method and support. Some of these properties were tightly bound to catalyst performance, in terms of H2 productivity and stability towards coking and sintering. A key parameter was the metal–support interaction, which strongly depended on the preparation procedure. In particular, the stronger the interaction, the more stable the metallic Ni clusters, which in turn lead to a higher catalytic activity and stability. Surface acidity was also taken into account, in which the nature of the acid sites was differentiated (silanols, titanols or Lewis acid sites). The characterisation of the spent catalysts also allowed us to interpret the deactivation process. The formation of multi-walled nanotubes was observed for every sample, though it was only in some cases that this led to severe deactivation.
    ChemCatChem 01/2013; 5(1). · 5.18 Impact Factor
  • Olga Buchneva, Alessandro Gallo, Ilenia Rossetti
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    ABSTRACT: LaMnO(3), either pure or doped with 10 mol % Sr, has been prepared by flame pyrolysis in nanostructured form. Such catalysts have been tested for the catalytic flameless combustion of methane, achieving very high catalytic activity. The resistance toward poisoning by some model N-containing impurities has been checked in order to assess the possibility of operating the flameless catalytic combustion with biogas, possibly contaminated by S- or N-based compounds. This would be a significant improvement from the environmental point of view because the application of catalytic combustion to gas turbines would couple improved energy conversion efficiency and negligible noxious emissions, while the use of biogas would open the way to energy production from a renewable source by means of very efficient technologies. A different behavior has been observed for the two catalysts; namely, the undoped sample was more or less heavily poisoned, whereas the Sr-doped sample showed slightly increasing activity upon dosage of N-containing compounds. A possible reaction mechanism has been suggested, based on the initial oxidation of the organic backbone, with the formation of NO. The latter may adsorb more or less strongly depending on the availability of surface oxygen vacancies (i.e., depending on doping). Decomposition of NO may leave additional activated oxygen species on the surface, available for low-temperature methane oxidation and so improving the catalytic performance.
    Inorganic Chemistry 10/2012; · 4.59 Impact Factor
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    ABSTRACT: The physical-chemical properties of some nanostructured perovskite-like catalysts of general formula La(1-x)M(x)MnO(3+δ) (M = Ce, Sr) have been investigated, in particular by using the electron paramagnetic resonance (EPR) technique. We show that the interplay between the -O-Mn(3+)-O-Mn(4+)-O- electron double-exchange and the electron mobility is strictly dependent on the dopant nature and the annealing conditions in air. A relationship between the observed properties of these samples and their activity in the methane flameless catalytic combustion is proposed.
    Inorganic Chemistry 07/2012; 51(15):8433-40. · 4.59 Impact Factor
  • Chimica oggi 05/2012; 30(3):29-32. · 0.54 Impact Factor
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    ABSTRACT: A power unit constituted by a reformer section, a H2 purification section and a fuel cell stack is being tested c/o the Dept. of Physical Chemistry and Electrochemistry of Università degli Studi di Milano, on the basis of a collaboration with HELBIO S.A. Hydrogen and Energy Production Systems, Patras (Greece), supplier of the unit, and some sponsors (Linea Energia S.p.A., Parco Tecnologico Padano and Provincia di Lodi, Italy). The system size allows to co-generate 5 kWe (220 V, 50 Hz a.c.) + 5 kWt (hot water at 65 °C) as peak output. Bioethanol, obtainable by different non-food-competitive biomass, is transformed into syngas by a pre-reforming and reforming reactors couple and the reformate is purified from CO to a concentration below 20 ppmv, suitable to feed a proton exchange membrane fuel cell (PEMFC) stack that will be integrated in the fuel processor in a second step of the experimentation. This result is achieved by feeding the reformate to two water gas shift reactors, connected in series and operating at high and low temperature, respectively. CO concentration in the outcoming gas is ca. 0.4 vol% and the final CO removal to meet the specifications is accomplished by two methanation reactors in series. The second methanation step acts merely as a guard, since ca. 15 ppmv of CO are obtained already after the first reactor.The goals of the present project are to test the integrated fuel processor, to check the effectiveness of the proposed technology and to suggest possible adequate improvements.
    International Journal of Hydrogen Energy 05/2012; 37(10):8499–8504. · 3.55 Impact Factor
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    ABSTRACT: Two V-SBA-15 and V-MCF materials (containing about 2.5wt.% vanadium) were prepared by direct synthesis and tested as catalysts in the decomposition of the most stable chlorinated-alkane, dichloromethane (a total oxidation reaction) and in the oxidative dehydrogenation (ODH) of propane (a partial oxidation reaction). Comparison was made with: (i) two V-SBA-15 and V-MCF materials prepared by “traditional” impregnation method and (ii) a non-porous V-SiO2 catalyst prepared by flame pyrolysis. All catalysts tested had a vanadium content of about 2.5wt.%. Samples properties were investigated by means of complementary techniques (TEM, IR and DR UV–vis spectroscopies, N2 sorption at −196°C) in order to find possible correlations between catalytic properties of the studied materials and their different physico-chemical features. It is shown that direct synthesis allows a better vanadium dispersion to be achieved, a feature that positively affects catalytic performances in both total and partial oxidations. The different porous networks of the SBA-15 and MCF supports also play an important role on catalytic activity: both V-SBA-15 samples gave better results in dichloromethane decomposition, whereas both V-MCF samples were more selective in propane ODH. The latter findings are ascribed to different molecules diffusion and residence time inside the channels of either SBA-15 or MCF networks.
    Catalysis Today - CATAL TODAY. 01/2012;
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    ABSTRACT: Site isolation of V active sites has been often correlated to catalytic performance for the oxidative dehydrogenation (ODH) of propane to propylene. In particular, catalyst selectivity seems favored by high V dispersion. The latter property is hardly attainable by traditional preparation methods, especially by impregnation except at very low V loading, which however may lead to a too high surface exposure of the acidic sites of the support. In this paper, the effect of the preparation procedure on catalyst properties has been investigated, particularly considering catalysts prepared by flame pyrolysis, a synthesis method which induced a very high V dispersion also at relatively high vanadium loading. Transmission electron microscopy also allowed us to assess V oxide dispersion depending on both the support type and the preparation method. Furthermore, the local structure of the V active sites has been deeply investigated by X-ray absorption spectroscopy, allowing us to propose a possible structure of the active sites. The average oxidation state of surface V species was then studied by X-ray photoelectron spectroscopy (XPS), showing a role of V oxidation state on catalyst selectivity. The catalytic performance has been interpreted on the basis of V species and catalyst acidity (as measured by IR spectroscopy), another fundamental parameter that in turn results to be correlated with V dispersion on different supports. More selective catalysts were indeed characterized by the presence of weaker Brønsted acidic sites.
    The Journal of Physical Chemistry C 01/2012; 116(42):22386. · 4.84 Impact Factor
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    ABSTRACT: We present here a X-ray absorption spectroscopy (XAS) investigation on the local chemical order and electronic structure of Cs and Ba, promoters of the Ru/C catalysts for ammonia synthesis that attracted interest because of highly increased productivity. The role of the promoters is still largely unclear, although indirect evidence for Cs partial reduction has been obtained by this and other groups. Our XAS analysis with in situ H(2) reduction directly supports the partial Cs reduction in the promoted Ru/C catalysts, depending on the presence of Ru and on the graphitization degree of the support. Higher coordination of Ba was observed with respect to Cs in the reduced samples, without evidence of heavy atoms (Ru, Cs, and Ba) in the surroundings. Because of the strong electropositive nature of Cs, direct experimental evidence of its partial reduction is of outstanding significance also for other applications.
    Inorganic Chemistry 03/2011; 50(8):3757-65. · 4.59 Impact Factor
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    ABSTRACT: Two V-SBA-15 and V-MCF materials (V content ca. 2.5wt.%) were prepared by direct synthesis and tested in the catalytic decomposition of dichloromethane. Their catalytic properties were compared to those of other materials with the same vanadium content, namely two mesoporous materials prepared by impregnation (V-SBA-15-i and V-MCF-i) and a non-porous one prepared by flame pyrolysis (V-SiO2). Both direct synthesis and flame pyrolysis methods allowed a better vanadium dispersion that lead to better catalytic properties above 350°C, due to the presence of well dispersed V species partially incorporated into silica. The higher dichloromethane conversion achieved with both V-SBA-15 and V-SBA-15-i samples, as compared to MCF samples, are ascribed to longer residence times of both reactants and products within SBA-15 mesoporous channels, in contrast to three-dimensional MCF ultra large pores facilitating diffusion. Below 350°C, both V-SBA-15-i and V-MCF-i samples showed higher dichloromethane conversion, basically due to the presence of micro-crystalline V2O5 formed at the external surface of both materials.
    Catalysis Today - CATAL TODAY. 01/2011; 176(1):458-464.
  • Ilenia Rossetti, Cesare Biffi, Lucio Forni
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    ABSTRACT: Perovskite-like LaBO3 catalysts (B=Co, Mn, Fe), prepared by flame pyrolysis, and doped with Ce, Sr or with small amounts of Pd or Pt were used for the flameless combustion of methane. The effect of the dopants on the reducibility of the B metal ion has been analysed comparatively, trying to correlate this parameter with catalytic activity. The higher the B3+ ion reducibility, the lower was the light off temperature of the reaction. However, the correlation with the temperature of half conversion revealed that a too high reducibility of the catalyst depressed the second step of the Mars–van Krevelen reaction mechanism, i.e. the reoxidation of active site.The quantitative elaboration of the TPR pattern allowed to determine oxygen non-stoichiometry, at least for the LaCoO3 based samples. Furthermore, the available oxygen amount was correlated to catalytic activity.
    Chemical Engineering Journal - CHEM ENG J. 01/2010; 162(2):768-775.
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    ABSTRACT: Perovskite-like structured catalysts showed satisfactory activity for the low temperature flameless combustion of methane. This process reduces the emission of CO, NOx and unburnt hydrocarbons. Partial metal ion substitution in the composition of perovskites may improve catalytic activity and it can modulate their resistance to sulfur poisoning. Silver is an interesting dopant due to its limited solubility in the perovskite structure and suitable activity both in extra- and intra-framework positions. The amount of lattice silver tightly depends on the preparation procedure. Samples with nominal composition La1 � xAgxMnO3 � d with x ¼ 0; 0.05; 0.10 were prepared by flame spray pyrolysis (FP) and by the so-called sol–gel citrate method (SG). Temperature-programmed analysis, X-ray powder diffraction (XRPD) and Electron Paramagnetic Resonance (EPR) spectroscopy were used as the main characterisation tools. Almost all of the catalysts were very active for the flameless combustion of methane. The activity of the FP-prepared catalysts was always higher than that of the SG-prepared ones with identical nominal composition. Furthermore, partial substitution of Ag for La led to substantially higher activity both for SG- and FP-prepared catalysts and the catalytic activity increased with increasing Ag substitution. The residual activity after poisoning with tetrahydrothiophene, a common odoriser used in the natural gas grid, is also presented, together with the transient response of the samples upon poisoning.
    Journal of Materials Chemistry 01/2010; 20:10021. · 5.97 Impact Factor
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    ABSTRACT: Here, we investigated the properties of Au nanoparticles prepared via three different techniques and supported on three different MgAl2O4 spinels. After careful characterization of bare and gold-loaded supports (XPS, BET, XRD, STEM) and catalytic test for the selective oxidation of glycerol, we concluded that the surface composition and area of the spinel play an important role in determining the selectivity of the catalyst as well as gold particle size. When supported on surface characterized by a similar Al/Mg ratio, gold clusters selectivity is not mediated by particle dimension. For example, large gold particles on MgAl2O4, which typically produce high selectivity to glycerate when supported on aluminum-rich surfaces instead, enhance the C–C bond cleavage reaction. Accordingly, the selectivity of similarly sized AuNPs on MgAl2O4 spinels with the same surface Al/Mg ratio is similar but we demonstrate that the activity depends on gold surface exposure (at.% Au by XPS) and on support surface area.
    Journal of Catalysis 01/2010; 275(1):108-116. · 5.79 Impact Factor
  • Ilenia Rossetti, Chiara Gambaro, Vincenzo Calemma
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    ABSTRACT: The hydrocracking reactivity of two model compounds, namely n-C16H34 (n-C16) and n-C28H58 (n-C28), was investigated on a Pt/SiO2-Al2O3 catalyst. Conversion and products distribution have been determined under a wide range of operating conditions (i.e. pressure: 20–80bar; temperature: 270–330°C; weight hourly space velocity: 0.33–1.0h−1; H2/n-paraffin feeding ratio 0.05–0.15wt/wt). The latter were changed according to a central composite design. The present paper summarises the results obtained on both the model paraffins, depending on the reaction conditions. A first, simple kinetic elaboration is also presented, based on an ideal PFR model and a first order kinetics. The reaction confirmed to be first order with respect to the n-paraffin. Experimental data showed that for both n-C16 and n-C28 conversion was affected by H2/n-paraffin ratio. The change of conversion was explained in terms of vapour liquid equilibrium (VLE), which in turn is affected by the H2/n-paraffin ratio, so leading to a different vaporisation degree of reactant. In agreement with the VLE data, the effect of H2/n-paraffin on conversion was lower for n-C28. VLE calculations have been carried out to estimate the H2 partial pressure and degree of vaporisation of the normal paraffin. The reaction order for hydrogen was −1 and −0.5 for n-C16 an n-C28, respectively. However, in the case of n-C16 the data obtained at the lower bound of the pressure range examined displayed an increase of the reaction order. The apparent activation energy was calculated after correction of the contact time taking into account the liquid-vapour equilibrium: similar values have been estimated for n-C16 and n-C28, ca. 32 and 31kcal/mol, respectively.
    Chemical Engineering Journal 11/2009; 154(1-3):295. · 3.47 Impact Factor
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    ABSTRACT: In the oxidative dehydrogenation (ODH) of propane to propylene VOx-based catalysts prepared by flame pyrolysis (FP) showed more selective than those prepared by impregnation. Furthermore, samples prepared by the same method were less active, but more selective when VOx was supported on SiO2 than on Al2O3. In order to assess V local structure, V4+ ions showed useful labels to characterise these catalysts by EPR spectroscopy. Indeed, the spectrum of a (10 wt%V2O5) FP-prepared VOx/SiO2 catalyst was typical of isolated, tetragonally distorted, paramagnetic complexes of V4+ forming a monolayer on the sample surface with a strong out-of-plane V4+–O bond. In a sample with identical composition, but prepared by impregnation, this bond showed a bit weaker. Furthermore, ferromagnetic domains of clustered V ions formed in the latter sample, hindering at least in part the accessibility to the catalytically active V-based centres. This gives evidence of the higher dispersion of V in the sample bulk provided by the FP preparation method with respect to conventional ones. A by far weaker V4+–O bond was revealed by the EPR spectrum of a (10%V2O5) VOx/Al2O3 sample, accounting for its higher oxygen availability, leading to higher activity, but lower selectivity. However, the same catalyst, when prepared by impregnation, showed a ferromagnetic resonance pattern so intense that no EPR spectrum was detectable at all and no information on the V4+–O bond strength was available in that case.Such semi-quantitative index of the V–O bond strength can be used as an index of oxygen availability, as a tool to assess catalytic activity and selectivity to the desired olefin.
    Chemical Engineering Journal. 11/2009; 154(s 1–3):131–136.
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    ABSTRACT: A flame pyrolysis (FP) procedure has been set up for the preparation of V/Al/O catalysts to be employed for the oxidative dehydrogenation of propane to propylene. The samples have been characterised by means of various techniques (FT-IR, Raman, EPR, ICP-MS, TGA, XRD, SEM) and their catalytic activity has been evaluated in two different operating modes, i.e. under anaerobic conditions and by co-feeding oxygen. The particle size distribution became progressively more homogeneous with increasing V concentration, due to the catalytic effect of the V ions during the FP synthesis. Some V2O5 segregation was observed even at low V loading. However, higher V dispersion was attained with respect to a reference sample prepared by impregnation of the FP-prepared alumina support.The increase of V concentration always led to an improvement of propane conversion, though selectivity showed different trends depending on the operating conditions. The comparison with the sample prepared by impregnation showed similar catalytic activity, with a bit higher selectivity for the FP-prepared sample under anaerobic conditions.
    Catalysis Today 03/2009; 141:271-281. · 2.98 Impact Factor

Publication Stats

147 Citations
115.79 Total Impact Points

Institutions

  • 1999–2014
    • University of Milan
      • • Department of Chemistry
      • • Department of Physical Chemistry and Electrochemistry
      • • Department of Chemistry, Biochemistry and Biotechnologies for Medical Sciences
      Milano, Lombardy, Italy
  • 2004
    • Università degli studi di Cagliari
      • Department of Surgical Science
      Cagliari, Sardinia, Italy