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Tra i più studiati poliossometallati (nanoagglomerati di ossigeno con metalli transizionali), figurano gli eteropoliacidi (EPA) che sono degli acidi inorganici forti con ben defin ite strutture molecolari. In funzione della loro geometria, essi vengono classificati come Keggin e Wells-Dawson. Gli (EPA) sono usati in catalisi omogenea ed eterogenea e funzionano anche come fotocatalizzatori, essenzialmente in sistemi omogenei. Questi materiali sono, inoltre, economici e non tossici.

Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/specific, “pin-point”, functionalization of HNTs with polydopamine (HNTs@PDA). This goal was achieved, at pH 6.5, by exploiting the basicity of ZnO nanoparticles anchored on the HNTs external surface (HNTs@ZnO) to induce a punctual polydopamine polymerization and coating. The morphology and the chemical composition of the nanomaterial was demonstrated by several techniques. Turbidimetric analysis showed that PDA coating affected the aqueous stability of HNTs@PDA compared to both HNTs@ZnO and HNTs. Notably, hyperthermia studies revealed that the nanomaterial induced a local thermic rise, up to 50 °C, under near-infrared (NIR) irradiation. Furthermore, secondary functionalization of HNTs@PDA by selective grafting of biotin onto the PDA coating followed by avidin binding was also accomplished.

In this work gold catalysts supported over SBA-15 with different CeO 2 loadings (5-30 wt%) were prepared, characterized by N 2 physisorption analyses, SAXS, XRD, STEM and XPS techniques and their catalytic performances were evaluated in the CO oxidation, chosen as reaction test. Over a selected catalyst, Au/CeO 2(20 wt%)-SBA-15, the effect of CO 2 and of the mixture (CO 2 + H 2O) on the CO conversion to CO 2 was also evaluated. Characterizations by SAXS, XRD, STEM and XPS were carried out on selected spent catalysts after CO oxidation. The results were discussed in terms of relationship between morphological, structural, electronic and catalytic properties as a function of the ceria loading. The CO oxidation activity was strongly affected by gold particle size and gold/ceria interface as well. For gold catalysts supported on ceria-doped SBA-15, the oxygen vacancies in ceria likely act as nucleation sites for gold anchoring and stabilization against sintering. The optimum of the catalytic performances was found for 20 wt% ceria loading, likely due to the optimum synergistic interaction between highly dispersed defective ceria oxide and nanosized gold. © 2012 Elsevier B.V. All rights reserved.

An Au/CeO2 model catalyst was prepared by deposition–precipitation, with the aim of obtaining a sample suitable for a detailed X-ray absorption fine structure (XAFS) analysis of the gold–ceria interface structure. The results demonstrate the existence of a large interface between the gold particle and the support oxide, characterized by well-defined Au–O and Au–Ce interactions extending up to ∼6.4 A. The complex interface structure is retained after CO treatment up to 250 °C and subsequent reoxidation at 400 °C. The analysis of the XANES spectra, and the Au–O distance of 2.21 A, longer than Au–O bond lengths previously reported for Au/ceria catalysts, suggest a low oxidation state for the gold atoms placed at the interface between Au and ceria.

Multilayered, covalently supported ionic liquid phase (mlc-SILP) materials were synthesized by using a new approach based on the grafting of bis-vinylimidazolium salts on different types of silica or polymeric supports. The obtained materials were characterized and tested as catalysts in the reaction of supercritical carbon dioxide with various epoxides to produce cyclic carbonates. The material prepared by supporting a bromide bis-imidazolium salt on the ordered mesoporous silica SBA-15 was identified as the most active catalyst for the synthesis of cyclic carbonates and displayed improved productivity compared with known supported ionic liquid catalysts. The catalyst retained its high activity upon reuse in consecutive catalytic runs. This is the first report of the application of mlc-SILP materials as catalysts in a reaction for the fixation of carbon dioxide. Rapid, parallel screening and comparison of the catalysts was performed by means of high-throughput experimentation.

The reaction between an excess of 1,4-bis(3-vinylimidazolium-1-yl) bromide and a mercaptopropyl-modified amorphous silica gel or ordered mesoporous silica SBA-15 in the presence of azobisisobutyronitrile (AIBN) afforded new materials, which have a high loading of imidazolium moieties. These materials, which contain a highly cross-linked polymeric network, have been denoted as multi-layered, covalently supported ionic liquid phase (mlc-SILP) and have been used as support for palladium catalysts containing a high loading of the metal (10 wt%). Such materials were characterized by several techniques (13C magic angle spinning nuclear magnetic resonance, the Brunauer–Emmett–Teller technique, small-angle X-ray scattering, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy). The presence of a homogeneous distribution of palladium nanoparticles was established. The palladium catalysts displayed good activity allowing the synthesis of several biphenyl compounds in high yields working with only 0.1 mol% of palladium loading at mild temperatures (room temperature or 50 °C) in ethanol/water. Reactions carried out on a 10-mmol scale required only 10 mg of catalysts. Good recyclability was observed.

A structured Pt(1 wt%)/ceria–zirconia/alumina catalyst and the metal-free ceria–zirconia/alumina were prepared, by dip-coating, over a cordierite monolithic support. XRD analyses and Rietveld refinements of the structural data demonstrate that in the Pt supported catalysts ceria–zirconia is present as a Ce 0.6 Zr 0.4 O 2 homogeneous solid solution and that the deposition over the cordierite doesn’t produce any structural modification. Moreover no Pt sintering occurs. By comparing the XRD patterns recorded on Pt/ceria–zirconia/alumina and ceria–zirconia/alumina after three redox cycles, it results that Pt, favouring the structural reorganization of the ceria–zirconia into one cubic solid solution, prevents any CeAlO 3 formation. On the contrary, such phase due to the interaction between Ce 3+ and the alumina present in the washcoat is detected when redox cycles are carried out on the ceria–zirconia metal free. Transmission electron microscopy (TEM) investigations of the redox cycled Pt/ceria–zirconia/alumina catalyst detected ceria–zirconia grains with diameter between 10 and 35 nm along with highly dispersed Pt particles (2–3 nm) strongly interacting with ceria. Scanning electron microscopy (SEM) and EDX analyses, recorded on the redox cycled Pt/ceria–zirconia/alumina washcoated monolith evidence a homogeneous distribution of the active components through the channels even after redox aging. Reduction behaviour and CO oxidation activity are in good agreement with the structural modification of the solid solution induced by the redox cycles and reflect the positive effect of Pt/ceria interaction on the catalytic performances. The effect of redox aging on the NO reduction by C 3 H 6 , in lean conditions, was investigated over the Pt/ceria–zirconia/alumina monolith. The catalyst shows at low temperature (290 °C) good NO removal activity and appreciable selectivity to N 2 .

La1−xSrxCr1−yFeyO3−δ (x = 0, 0.1, 0.15, 0.2; y = 0, 0.3, 0.5) perovskite-type oxide powders were synthesized by solution combustion synthesis and characterized by X-ray diffraction, X-ray photoelectron spectroscopy and H2-temperature programmed reduction. Selected compositions were studied by CH4-temperature programmed reduction in the absence and in the presence of H2S. Temperature programmed oxidation and structural characterizations were performed in order to discriminate the nature of residual deposits on the catalyst surface. The study about reduction in different methane-based mixture revealed that total and partial methane oxidation occurred in the range ∼450–1000 °C independently of methane concentration. The H2S influence on methane oxidation was evaluated and experiments in CH4/H2S gas mixture indicated that La0.9Sr0.1Cr0.7Fe0.3O3−δ oxidized CH4 to CO2 and CO, as well as H2S to SO2. La0.9Sr0.1Cr0.7Fe0.3O3−δ was therefore identified a potential anode material for intermediate temperature solid oxide fuel cells directly fed with CH4 in the presence of H2S.

A catalyst with 0.7 wt% Pd load supported over Co3O4 oxide was investigated in the methane oxidation by operating under CH4/O2 stoichiometric conditions. The effect of the noble metal addition on the activity of bare Co3O4 was evaluated. Samples were characterized by BET, XRD, TPR and XPS analyses. The SO2 poisoning of Pd catalyst and Co3O4 was studied by performing CH4 oxidation tests under stoichiometric conditions in SO2 (1 ppm or 10 ppm). Experiments evidenced that in our conditions the low amount of SO2 doesn’t influence the Pd behaviour, whereas in presence of 10 ppm of SO2 some deactivation occurs that becomes more evident above 450 °C at which the catalyst doesn’t reach 100% of methane conversion. Catalytic tests performed over Co3O4 and the Pd supported catalyst, after a treatment at 350 °C for 15 h in 10 ppm SO2/He, suggest that Co3O4 is a sulphating support, as confirmed by XPS analysis. Therefore, an important role in lowering the sulphur poisoning of Pd may be played by Co3O4.

Co3O4/CeO2 and Co3O4/CeO2–ZrO2 composite catalysts have been prepared by two different techniques, co-precipitation by citrate method and impregnation with cobalt nitrate of pre-formed ceria and ceria–zirconia oxides. The materials, as prepared and after ageing at 750 °C 7 h, were tested for methane combustion and the catalytic performances were compared with those of a commercial Co3O4, used as reference. A significant improvement of the activity was observed in the composite oxide Co3O4(30 wt%)/CeO2(70 wt%), prepared by citrate method, which exhibits the lowest light-off temperature of methane (T50 = 400 °C) and does not suffer deactivation after calcination at 750 °C 7 h.

Temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPO) have been used to study the various cobalt species formed in a cobalt catalyst (Co 1 wt.%) supported on alumina-baria, with composition Al2O3(80 wt.%)–BaO (20 wt.%). The catalyst was synthesized by incipient-wetness impregnation of the support with a water solution of cobalt acetylacetonate and calcined at 550 °C for 5 h. In order to investigate the structure and morphology of the sample, XRD, BET and SEM analyses were performed. Depending on the temperature and nature of pre-treatment (reductive or oxidative) different Co species (Co3O4, Co3+, surface Co2+, CoAl2O4) were formed. Activity tests in the reduction of NO by CO were carried out in order to investigate the effectiveness of the catalyst depending on the redox pre-treatment. Highly dispersed Co3O4 particles, formed after a TPR up to 1100 °C and successive TPO up to 550 °C are active for the NO reduction at low temperature, N2O being the major product at 250 °C, while N2 formation was favored at temperature higher than 400 °C. The as prepared sample, calcined at 550 °C for 5 h, exhibits significant activity only at temperature > 400 °C, giving selective formation of N2. The nature of the active species in the supported catalyst was confirmed by studying the CO + NO reaction and NO decomposition over Co3O4 and CoO oxides as reference materials. On Co3O4 the NO reduction occurs with different selectivity to N2O/N2, depending on the reaction temperature: at low temperature only N2O was detected, whereas at temperature >350 °C also N2 formation was observed. Then at temperature ≥450 °C only the reaction NO→N2 takes place. Over CoO the reaction starts at ∼400 °C and N2 is the only nitrogen product detected in the whole range of temperature investigated. Hundred percent of NO conversion into N2 is reached at 600 °C.

LaCoO3 perovskites substituted by Sr at the A site and/or by Fe at the B site have been prepared by the citrate method. Characterizations by several techniques, such as specific surface area (BET method), XRD, TPR, SEM, UV–vis in DRS mode, XPS and TGA analyses, have been performed. The so prepared La1−xSrxCo1−yFeyO3−δ perovskites are semiconductor materials showing band gap energy values from 1.9 to 3.2 eV. They displayed solar photocatalytic activity for the 2-propanol degradation in gas–solid regime. The photocatalytic results suggest that the perovskites containing Fe are less active and the activity decreases by increasing the Fe content, however the presence of iron avoids the catalyst deactivation. The best photocatalytic activity in the 2-propanol degradation was found for the sample La0.6Sr0.4CoO3−δ.

A modular approach has been followed for the synthesis of a series of fullerene-ionic-liquid (IL) hybrids in which the number of IL moieties (two or twelve), anion, and cation have been varied. The combination of C60 and IL give rise to new unique properties in the conjugates such as solubility in water, which was higher than 800 mg mL(-1) in several cases. In addition, one of the C60 -IL hybrids has been employed for the immobilization of palladium nanoparticles through ion exchange followed by reduction with sodium borohydride. Surprisingly, during the reduction several carbon nanostructures were formed that comprised nano-onions and nanocages with few-layer graphene sidewalls, which have been characterized by means of thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDAX), and high-resolution transmission electron microscopy (HRTEM). Finally, the material thus obtained was successfully applied as catalyst in Suzuki and Mizoroki-Heck reactions in a concentration of just 0.2 mol %. In the former process it was recyclable for five runs with no loss in activity.

Steam reforming of light hydrocarbons provides a promising method for hydrogen production. Ni-based catalysts are so far the best and the most commonly used catalysts for steam reforming because of their acceptably high activity and significantly lower cost in comparison with alternative precious metal-based catalysts. However, nickel catalysts are susceptible to deactivation from the deposition of carbon, even when operating at steam-to-carbon ratios predicted to be thermodynamically outside of the carbon-forming regime. Reactivity and deactivation by carbon formation can be tuned by modifying Ni surfaces with a second metal, such as Au through alloy formation. In the present review, we summarize the very recent progress in the design, synthesis, and characterization of supported bimetallic Ni-based catalysts for steam reforming. The progress in the modification of Ni with noble metals (such as Au and Ag) is discussed in terms of preparation, characterization and pretreatment methods. Moreover, the comparison with the effects of other metals (such as Sn, Cu, Co, Mo, Fe, Gd and B) is addressed. The differences of catalytic activity, thermal stability and carbon species between bimetallic and monometallic Ni-based catalysts are also briefly shown.

Gold catalysts with loading 1 and 10 wt % were-prepared by deposition precipitation method with urea over mesoporous manganese oxide, obtained through a surfactant-assisted procedure by using cetyltrimethylammonium bromide (CTAB), followed by treatment with sulphuric acid. For comparison, Au(10 wt %) was also deposited over commercial CeO2 and SiO2 supports. The materials were characterized by XRD and EXAFS at the Mn K and Au L-III edges and XPS. Moreover, the analyses were performed on the samples treated under 1%CO/He, at 250 degrees C for 90 min. The structural and surface results of the as prepared manganese oxide confirmed the formation of gamma-MnO2 along with some amorphous Mn3O4 upon treatment of the precursor oxide with sulphuric acid. The CO treatment induces the formation of reduced phases, Mn3O4 (Hausmannite) and Mn2O3 (Bixbyite). Gold particles have a positive effect in promoting the reduction of manganese oxide and this effect is more pronounced in the Au(10 wt %) catalyst, which exhibits an enhanced CO oxidation activity with respect to both the Au(1 wt %) sample and the metal-free manganese oxide. The higher efficiency of Au(10 wt %) catalyst is attributed to a strong metal-support interaction between gold nanoparticles and support, as demonstrated by the presence of a component Au-O at 2.1 angstrom in the Fourier transform of the EXAFS signal of both the fresh and the CO-treated samples.

The present work investigates the effect of ceria loading on silica SBA-15. Five CeO2/SBA-15 samples with CeO2 content equal to 5, 10, 15, 20 and 30 wt% were prepared by wetness-impregnation of the support with cerium nitrate hexahydrate, as precursor, dissolved in ethanol. After drying at room temperature, the resulting samples were calcined at 400 °C for 2h. Characterizations by BET surface area and pore-size distribution, XRD, NH3-TPD and H2-TPR were performed.

Ceria nanosized oxides with high surface area were synthesized by means of a templating approach, using a porous silica xerogel with surface area as high as 718 m2/g. After impregnation of the silica template with the cerium salt solution and further calcination at 600 °C, the final ceria oxide was recovered by dissolving the silica framework in NaOH solution. The effect of cerium counteranion, nitrate or chloride, on the textural and reduction properties of the ceria oxide was examined. Characterizations by BET and pore size distribution, XRD, TPR and SEM/EDX techniques were performed. The silica xerogel templated approach resulted in the preparation of ceria with surface area of 205 m2/g and very small particle size (∼5 nm), when cerium chloride precursor was used. An enhanced reducibility, at temperature

A structured Co3O4–CeO2 composite oxide, containing 30% by weight of Co3O4, has been prepared over a cordieritic honeycomb support. The bimetallic, Pd–Pt catalyst has been obtained by impregnation of the supported Co3O4–CeO2 with Pd and Pt precursors in order to obtain a total metal loading of 50 g/ft3. CO, CH4 combined oxidation tests were performed over the catalyzed monoliths in realistic conditions, namely GHSV = 100,000 h−1 and reaction feed close to emission from bi-fuel vehicles. The Pd–Pt un-promoted Co3O4–CeO2 is promising for cold-start application, showing massive CO conversion below 100 °C, in lean condition. A strong enhancement of the CH4 oxidation activity, between 400 and 600 °C, has been observed by addition to the Co3O4–CeO2 of a low amount of Pd–Pt metals.

The catalyst Pt(1 wt %)/Ce(0.6)Zr(0.4)O(2) is studied by CO-temperature programmed reduction (CO-TPR), isothermal oxygen storage complete capacity (OSCC), X-ray absorption spectroscopy (XAS) at the Pt L(III) edge, and in situ X-ray diffraction (in situ XRD), with the aim of elucidating the role of supported metal in CO oxidation by ceria-based three-way catalysts (TWC). The redox behavior of Pt(1 wt %)/Ce(0.6)Zr(0.4)O(2) is compared to that of bare ceria-zirconia. OSCC of redox-aged Pt/ceria-zirconia is twice that of bare ceria-zirconia, and the maximum of CO consumption occurs at a temperature about 300 K lower than redox-aged ceria-zirconia. XAS analysis allows one to evidence the formation of a platinum-cerium alloy in redox-aged samples and the stability of the metal particles toward oxidation and sintering during high-temperature treatments. Under CO flux at 773 K, bare ceria-zirconia shows a continuous drift of diffraction peaks toward smaller Bragg angles, due to a progressive increase of Ce(III) content. Under the same treatment, the structural rearrangement of Pt-supported ceria-zirconia starts after an induction time and takes place with an abrupt change of the lattice constant. The experimental evidence points to the role of supported Pt in modifying the redox properties of ceria-zirconia with respect to the bare support. It is proposed that the much faster bulk reduction observed by in situ XRD for redox-aged Pt/ceria-zirconia can be attributed to an easier release of reacted CO(2), producing a more effective turnover of reactants at the catalyst surface.

Nanostructured perovskite-type Sr1−aCeaFeO3−x, (0⩽a

Two structured composite oxides, Co3O4(30wt%)-CeO2(70wt%), have been prepared by washcoating commercial cordierite monoliths with a CeO2-γAl2O3 layer, on which the active phase Co3O4-CeO2 was added through two different methods: dip-coating from a suspension containing the preformed active oxide or impregnation with a solution of the cobalt and cerium precursors. Morphological characterizations of the monoliths have been performed by BET, and SEM-EDAX analyses. Electronic and reduction properties have been evaluated by XPS and H2-TPR, respectively. The effect of the preparation method has been investigated in the catalytic oxidation of CO, whereas the promotion by a low content of Pd-Pt has been evaluated in combined CO-CH4 oxidation tests. Four successive CO oxidation cycles performed over the structured Co3O4-CeO2 indicate that the best performing sample is the monolith prepared by dip-coating, whereas that one obtained by impregnation method manifests a certain deactivation upon two consecutive cycles. Accordingly, XPS spectra are consistent with the presence of the active phase CO3O4 in the former, while Co2+ has been identified as the main species in the latter sample.

Several compositions of palladium-loaded calcium hydroxyapatite Pd(x)/CaHAp were prepared and characterized by XRD, IR, and UV–visible spectroscopy and temperature-programmed reduction (TPR). The acid–base properties of the samples were studied with the use of butan-2-ol conversion and IR spectroscopy coupled with lutidine adsorption/desorption. Calcium hydroxyapatite bears Lewis acid sites of moderate strength and a limited number of Bronsted acid sites, which produce butenes by dehydration. The selectivity of the dehydrogenation reaction (formation of methyl ethyl ketone) is very limited in the absence of oxygen but indicates the existence on the surface of phosphate of basic sites that are as essential as the acid sites in the direct synthesis of methyl isobutyl ketone (MIBK) from acetone and H2. Dispersion of Pd on the hydroxyapatite introduces redox properties and the bifunctionality needed in the hydrogenation of mesityl oxide (MO). Temperature-programmed reduction (TPR) of Pd(x)/CaHAp catalysts shows a sharp peak of H2 consumption between 268 and 276 K, depending on palladium loading, followed by a negative peak at about 338 K, which is associated with the decomposition of β-PdH. Hydrogen chemisorption measurements carried out at 353 K allowed the determination of the size of palladium particles, which varies between 8 and 28 nm. The Pd(x)/CaHAp catalysts showed good performance in the low-pressure one-step synthesis of MIBK. They are stable under the experimental conditions, and they exhibit a MIBK and MIBC selectivity that reaches 92% for a conversion of 22% and an optimal Pd loading of 2 wt%. Other parameters of the reaction (such as temperature of reaction, residence time, H2/acetone ratio) were studied. They all play an important role in acetone conversion and product distribution. However, the reaction temperature has the most significant influence, since a maximum of the global conversion was observed at 423 K.

The steady-state activity of NO reduction by C3H6, in lean conditions, was studied on a Pt(1%)/Ce0.6Zr0.4O2 catalyst, in a plug-flow reactor, in the temperature range 100–500 °C. The influence of reductive pre-treatments on the catalytic performance at low temperature (250 °C) was investigated. Enhancement of the activity was found for the catalyst pre-treated in hydrogen at 350 °C as compared to the sample pre-treated in H2 at 800 and 1050 °C. Moreover, transient reactivity tests of NO reduction by hydrogen were also carried out. As previously observed, the sample reduced at 350 °C was the most active catalyst. In both types of reactions the temperature and the nature of pre-treatments had no effect on the selectivity to N2 at the temperature of maximum NO conversion. Analyses by temperature programmed reduction (TPR), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) supported the occurrence of a strong metal–support interaction (SMSI) effect between platinum and ceria and the important role of the platinum in promoting the ceria-zirconia structural reorganization. Such type of interaction determined a decrease of the platinum and ceria reduction temperature and a stabilization of the platinum oxide even in reducing atmosphere at high temperature. The catalytic behavior of the Pt/ceria-zirconia catalyst was discussed in terms of the structural and electronic modifications induced by the SMSI effect.

The structural evolution of two Pt/ceria–zirconia catalysts, characterized by different amounts of supported Pt, was monitored by in situ X-ray diffraction during the anaerobic oxidation of CO at different temperatures. In a first phase, oxygen coming from the surface layers of the ceria–zirconia mixed oxide is consumed and no structural variation of the support is observed. After this induction time, bulk reduction of Pt/ceria–zirconia takes place as a step-like process, while the CO2 production continues at a nearly constant rate. This behavior is totally different from that of the metal-free support in similar reaction conditions, that show a gradual bulk reduction. In repeated oxidation–reduction cycles, it was observed that the induction time in Pt/ceria–zirconia is a function of the thermal history, of the amount of supported Pt and of the structural evolution of the samples. r 2003 Elsevier Inc. All rights reserved.

Chromium oxide samples supported over silica and zirconia were prepared by wet impregnation of the supports with aqueous solution of CrO3. In order to investigate the influence of the preparation method on the chromium dispersion and oxidation state, one sample was prepared by sol-gel technique. The materials were structurally characterized by XRD analysis. The oxidation states of chromium species were investigated by XPS, DRS and TPR/TPO techniques. EPR analyses were also carried out for the sample Cr/SiO2, that due to the low crystalline state exhibits broad XPS signals. In this case, particular attention was paid to the presence of Cr(V) and Cr (III) species and their concentration. The oxidizing performances of the chromia supported reagents have been evaluated for the liquid phase oxidation of benzyl alcohol to benzaldeyde, in absence of molecular oxygen. With the aim to investigate the redox behaviour of anchored Cr and to evaluate the amount of regenerable Cr species (upon TPR/TPO process), oxidation tests were carried out on fresh and aged samples (i.e. after 7 redox cycles up to 600degreesC). A correlation was found between the benzyl alcohol conversion and the amount of chromium reduced by TPR of used samples (i.e. after 22 h of reaction). (C) 2004 Elsevier B.V. All rights reserved.

Two Al 2 O 3 (24 wt%)–La 2 O 3 (76 wt%) supported Co–La oxides with Co loading 4 wt% and different La content (1 and 9 wt%) were prepared by co-impregnation of the support, the aluminum–lanthanum oxide, with cobalt and lanthanum nitrates in aqueous solution and successive calcination at 800 °C for 4 h. The alumina–lanthana was synthesized by the sol–gel method. The samples were characterized by X-ray diffraction (XRD) and Rietveld refinement in order to identify the crystalline phases and their relative weight. H 2 -TPR (Temperature Programmed Reduction) experiments were recorded with the aim to identify the different Co phases present. Co 3 O 4 and LaCoO 3 were formed for La loading of 1%, whereas at higher La loading (9%) LaCoO 3 and La 2 O 3 oxide prevailed. In both catalysts LaAlO 3 phase was also detected. As observed by BET and SEM characterizations, the morphology of the two catalysts was somewhat affected by La:Co atomic ratio and differed dramatically from those of the reference bulk oxides, Co 3 O 4 and the mixed phase LaCoO 3 /La 2 O 3 . Activity tests in C 3 H 6 and CH 4 combustion were carried out in order to discriminate the catalytic properties of different phases formed (Co 3 O 4 , LaCoO 3 , La 2 O 3 , LaAlO 3 ).

Catalytic and catalytic photo-assisted hydration of propene to form 2-propanol in gas–solid regime at atmospheric pressure and 85 1C were carried out by using a heteropolyacid (POM) supported on different oxides. Binary materials were prepared by impregnation of H3PW12O40 on different commercial and home prepared supports (TiO2, SiO2, WO3, ZrO2, ZnO, Al2O3). Some of the composites were active both for catalytic and catalytic photo-assisted reactions. The Keggin type POM was completely and partially degraded, when supported on ZnO and Al2O3, respectively, and these binary solids always resulted as inactive for both catalytic and catalytic photo-assisted reactions. The supported Keggin POM species played a key role both for the catalytic and the photo-assisted catalytic reactions, due to their strong acidity and ability to form strong oxidant species under UV irradiation, respectively. The contemporary presence of heat and UV light improved the activity of almost all POM supported materials. All materials were characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM), diffuse reflectance spectroscopy (DRS), determination of the conduction and valence band energy by photovoltage measurements, Fourier transform infrared spectroscopy (FTIR), NH3-TPD experiments and time resolved microwave conductivity (TRMC). Introduction Propene hydration to obtain 2-propanol is a reaction carried out at moderate temperatures (ca. 150–200 1C) and pressure (2MPa) in the presence of an acid catalyst;1 however the realization of this reaction at ambient conditions is of great interest. The use