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Mechanochemical synthesis of Sb2S3 and Bi2S3 nanoparticles

Dutkova, E; Takacs, L; Sayagues, MJ; Balaz, P; Kovac, J; Satka, A
Chemical Engineering Science, 85 (2013) 25-29


The mechanochemical synthesis of Sb2S3 and Bi2S3 nanoparticles has been studied, starting from the corresponding metals and sulfur and using high-energy mechanochemical processing in a planetary laboratory mill. XRD, specific surface area measurement, SEM and TEM (HRTEM) with ED were used for the characterization of the nanoparticles. The XRD patterns confirmed the production of Sb2S3 (JCPDS 42–1393, orthorhombic) and Bi2S3 (JCPDS 17–320, orthorhombic) nanopowders. The transformation is about three times faster in the Bi–S than in the Sb–S system. The kinetics of the reaction has been determined from XRD line intensities. The grain size is about 30 nm for Sb2S3 and 24 nm for Bi2S3. The particles are highly agglomerated due to their nanometer size consequent large specific surface area. Unlike more conventional methods, mechanochemical synthesis is a simple and fast alternative for the preparation of these nanopowders that can be carried out at ambient temperature and atmospheric pressure.

January, 2013 | DOI: 10.1016/j.ces.2012.02.028

Strong quantum confinement effects in SnS nanocrystals produced by ultrasound-assisted method

Azizian-Kalandaragh, Y; Khodayari, A; Zeng, ZP; Garoufalis, CS; Baskoutas, S; Gontard, LC
Journal of Nanoparticle Research, 15 (2013) 1388


Nanocrystalline SnS powder has been prepared using tin chloride (SnCl2) as a tin ion source and sodium sulfide (Na2S) as a sulfur ion source with the help of ultrasound irradiation at room temperature. The as-synthesized SnS nanoparticles were quantitatively analyzed and characterized in terms of their morphological, structural, and optical properties. The detailed structural and optical properties confirmed the orthorhombic SnS structure and a strongly blue shifted direct band gap (1.74 eV), for synthesized nanoparticles. The measured band gap energy of SnS nanoparticles is in a fairly good agreement with the results of theoretical calculations of exciton energy based on the potential morphing method in the Hartree–Fock approximation.

January, 2013 | DOI: 10.1007/s11051-012-1388-1

Influence of the milling parameters on the mechanical work intensity in planetary mills

Gotor, FJ; Achimovicova, M; Real, C; Balaz, P
Powder Technology, 233 (2013) 1-7


The formation of ZnSe via a mechanically-induced self-sustaining reaction (MSR) from a Zn/Se mixture showed that only size reduction and mixing of the reactants without product formation occurred during the induction period prior to ignition. Therefore, all mechanical energy supplied by the planetary mill during this time, called the ignition time (tig), was used exclusively in the activation of the reactants. This system was chosen to study the dependence of tig on the main parameters characterising the milling intensity of planetary mills. The variation of the ignition time with the process conditions reflected changes in the mechanical dose rate of the planetary mill. A direct relationship between the inverse of the ignition time and the power of the planetary mill was established, which allows the validation of theoretical models proposed in the literature for the energy transfer in milling devices and the comparison of milling equipment efficiencies.

January, 2013 | DOI: 10.1016/j.powtec.2012.08.031

Synthesis and functionalization of biocompatible Tb:CePO4 nanophosphors with spindle-like shape

Rodriguez-Liviano, S; Aparicio, FJ; Becerro, AI; Garcia-Sevillano, J; Cantelar, E; Rivera, S; Hernandez, Y; de la Fuente, JM; Ocana, M
Journal of Nanoparticle Research 15 (2013) 15:1402


Monoclinic Tb:CePO4 nanophosphors with a spindle-like morphology and tailored size (in the nanometer and micrometer range) have been prepared through a very simple procedure, which consists of aging, at low temperature (120 °C), ethylene glycol solutions containing only cerium and terbium acetylacetonates and phosphoric acid, not requiring the addition of surfactants or capping agents. The influence of the heating mode (conventional convection oven or microwave oven) and the Tb doping level on the luminescent, structural and morphological features of the precipitated nanoparticles have also been analyzed. This study showed that microwave-assisted heating resulted in an important beneficial effect on the luminescent properties of these nanophosphors. Finally, a procedure for the functionalization of the Tb:CePO4 nanoparticles with aspartic-dextran is also reported. The functionalized nanospindles presented negligible toxicity for Verocells, which along with theirs excellent luminescent properties, make them suitable for biomedical applications.

January, 2013 | DOI: 10.1007/s11051-012-1402-7

Generalized master plots as a straightforward approach for determining the kinetic model: The case of cellulose pyrolysis

Sanchez-Jimenez, PE; Perez-Maqueda, LA; Perejon, A; Criado, JM
Thermochimica Acta, 552 (2013) 54-59


The thermal degradation of cellulose is a complex reaction and, despite the large amount of work by many investigators during the last decades, the actual understanding of the thermal decomposition kinetics is still very limited. Thus, while several mechanisms have been proposed to describe the process, the real model has not yet been clearly identified. In this paper, a set of experimental curves recorded under different heating schedules, i.e., linear heating rate, isothermal and constant rate thermal analysis (CRTA), has been analyzed using isoconversional and master plots methodology to discriminate the kinetic model followed by the reaction.

January, 2013 | DOI: 10.1016/j.tca.2012.11.003

Small Pt nanoparticles on the TiO2 (110)–(1 × 2) surface

Sanchez-Sanchez, C; Martin-Gago, JA; Lopez, MF
Surface Science, 607 (2013) 159-163


Scanning tunnelling microscopy (STM) has been used to study the initial stages of Pt deposition on the TiO2 (110)–(1 × 2) surface. Experimental STM images recorded for Pt coverage of 0.1 and 0.4 ML, suggest a Volmer-Weber growth. For low coverage and RT deposition, small clusters homogeneously distributed on the surface terraces are observed. However, after annealing at 825 K, material agglomeration, with nucleation mainly at the cross-links, is observed as a consequence of Pt diffusion on the surface. Finally, the structure of small clusters has been determined, in good agreement with previous theoretical calculations.

January, 2013 | DOI: 10.1016/j.susc.2012.08.028

Tribological properties of surface-modified Pd nanoparticles for electrical contacts

Abad, MD; Sanchez-Lopez, JC
Wear, 297 (2013) 943-951


A fully comprehensive study of the tribological behavior of palladium nanoparticles (Pd NPs) capped by tetrabutylammonium chains using a ball-on-disk tribometer under different conditions of applied load, concentration, tribometer motion, linear speed and nature of the counterface is revised. A low concentration of NPs (2 wt%) in tetrabutylammonium acetate was found sufficient to improve the tribological properties due to the formation of a protective transfer film (TF) comprised of metallic Pd. The increase of the applied load (up to 20 N, 1.82 GPa of contact pressure) confirmed the excellent extreme-pressure behavior avoiding the counterfaces from severe wear. After a running-in period whose duration depends on the operating conditions, the TF build-up allows to maintain a low contact electrical resistance through the contact (<0.1 kΩ) during the entire test. When the Pd NPs are used with ceramic counterfaces, the nanoparticles increase the load-bearing capabilities and performance of the base without forming TF, likely by mixed or boundary lubrication and healing effects. Finally, the Pd NPs are demonstrated to be useful as a thin solid lubricant film in reciprocating motion yielding a comparable tribological behavior. Hence, the presented surface Pd NPs can be very helpful to extend life of sliding components due to their high strength resistance providing a gateway to electrical conduction as well.

January, 2013 | DOI: 10.1016/j.wear.2012.11.009

Electrochromism in WOx and WxSiyOz Thin Films Prepared by Magnetron Sputtering at Glancing Angles

Garcia-Garcia, FJ; Gil-Rostra, J; Yubero, F; Gonzalez-Elipe, AR
Nanoscience and Nanotechnology Letters, 5 (2013) 89-93


This work reports the electrochromic evaluation of WxSiyOz and WOx glad thin films deposited by reactive magnetron sputtering at glancing angle. Their electrochemical properties were assessed by the analysis of cyclic voltammetry and chronoamperometry measurements in 0.1 M HClO4, whereas their optical properties were determined by studying their transmission and absorption spectra under operation conditions. Both types of thin films presented outstanding electrochromic properties characterized by a fast response, a high coloration and a complete reversibility after more than one thousand cycles.

January, 2013 | DOI: 10.1166/nnl.2013.1449

Colour and ultrasound propagation speed changes by different ageing of freezing/thawing and cooling/heating in granitic materials

Inigo, AC; Garcia-Talegon, J; Vicente-Tavera, S; Martin-Gonzalez, S; Casado-Marin, S; Vargas-Munoz, M; Perez-Rodriguez, JL
Cold Regions Science and Technology, 85 (2013) 71-78


In the present work we determined the chromatic coordinates (L*, a*, b*) and ultrasound propagation speeds on the three spatial planes (Vx, Vy, Vz) of three ornamental granites (Aqueduct of Segovia, Spain) before, during, and after being subjected to 70 cycles of two types of accelerated ageing (typical of cold regions): a) freezing/thawing and cooling/heating (T1), and b) freezing/thawing and cooling/heating + salt crystallization (T2). A multivariate technique (Canonical Biplot) was applied to the data obtained, with the observation of significant variations between the two types of accelerated artificial ageing as compared with those obtained in quarry rock in the three chromatic coordinates (L*, a*, b*). With regard to the ultrasound propagation speed, we only detected differences in the results of the T2 artificial ageing treatment with respect to those of quarry rock. This fact is confirmed by the estimated data of resistance to compression.

January, 2013 | DOI: 10.1016/j.coldregions.2012.08.004

Gas-phase Photocatalytic Partial Oxidation of Cyclohexane to Cyclohexanol and Cyclohexanone on Au/TiO2 Photocatalysts

Sannino, D; Vaiano, V; Ciambelli, P; Murcia, JJ; Hidalgo, MC; Navio, JA
Journal of Advanced Oxidation Technologies, 16 (2013) 71-82


The heterogeneous photocatalytic partial oxidation of cyclohexane in gas-phase as an alternative green process for fine chemicals synthesis was successfully achieved on Au/TiO2 photocatalysts prepared by photodeposition technique. Different gold loadings ranging between 0.5 and 2 wt.% of photodeposited Au on TiO2 synthesized by sol-gel method were obtained by changing the concentration of gold precursor at fixed illumination intensity and time. The cyclohexane partial photoxidation was conducted in a gas-solid photocatalytic fluidized bed reactor at high illumination efficiency. Main observed reaction products were cyclohexanol, cyclohexanone and CO2. The resulting selectivity was dramatically influenced by the gold content. The reaction temperature was a critical parameter to reach the photocatalysts stability, avoiding deactivation phenomena while the tuning of Au content of the photocatalysts, resulted in the promotion of the formation of cyclohexanol or cyclohexanone with high selectivity. In particular, by increasing Au content, the process selectivity is completely reversed, passing from high cyclohexanol selectivity (75%) to high selectivity to cyclohexanone (80%). These promising results evidenced that Au/TiO2 catalysts in the selected operating conditions, are effective materials for the synthesis of cyclohexanone and cyclohexanol in gas-phase by photocatalysis, at very low reaction temperatures and without the additional step of catalyst recovering needed in the liquid partial oxidation of cyclohexane.

January, 2013 | DOI: ---

Reverse osmosis membranes oxidation by hypochlorite and chlorine dioxide: spectroscopic techniques vs. Fujiwara test

Sandin, R; Ferrero, E; Repolles, C; Navea, S; Bacardit, J; Espinos, JP; Malfeito, JJ
Desalination and water treatment, 51 (2013) 318-327


The aim of this work was the study of degradation of a commercial polyamide membrane by two commonly employed oxidants for disinfection in seawater desalination, hypochlorite, and chlorine dioxide. A conventional reverse osmosis (RO) membrane is a thin film composite membrane composed of three different layers, a polyester support web, a microporous polysulfone interlayer, and a thin cross-linked polyamide barrier layer on the top surface, which is the active layer of the RO membrane. The degree of membrane degradation in seawater was evaluated in terms of decline in membrane performance calculated from permeability and salt rejection. In order to establish a relationship between the hydraulic properties and spectroscopic data, infrared and X-ray photoemission techniques (ATR-FTIR and XPS) were employed. The obtained results were compared with the Fujiwara test which is usually performed in membrane autopsies to check the degradation of polyamides with halogens. The chemical degradation of the surface active layer was analyzed using infrared spectroscopy (ATR-FTIR) by monitoring the changes in the characteristic infrared bands of the polyamide. It is possible to calculate the transmittance bands ratio between peak at 1540 cm(-1) (due to amide II) and peak at 1585 cm(-1) (due to the polysulfone layer) in order to get the comparison of the degraded membranes with a virgin membrane. The amide II band was selected to evaluate the degradation process, because it is the first band that reduces its transmittance value when the degradation process begins. Once the ratio is obtained for the degraded membrane and considering the value obtained from the virgin membrane as the reference point, a new index is calculated named as degradation index. The higher the parameter is, the greater the chemical attacks the polyamide layer. X-ray spectroscopy (XPS) measures the elemental composition and the chemical state of the elements that exist in the surface of a solid. Evaluation of the binding energy is possible to determine if the halogens are attached to the polyamide structure. It was concluded in this work that both spectroscopic techniques ATR-FTIR and XPS could detect the membrane degradation process earlier than Fujiwara test.

January, 2013 | DOI: 10.1080/19443994.2012.700010


Nanoporous silica microparticle interaction with toll-like receptor agonists in macrophages

Cejudo-Guillen, M; Ramiro-Gutierrez, M L; Labrador-Garrido, A; Diaz-Cuenca, A; Pozo, D
Acta Biomaterialia, 8 (2012) 4295-4303


Nanoporous silica microparticles (NSiO2-MP) are considered to be potential drug delivery systems and scaffolding platforms in tissue engineering. However, few biocompatibility studies regarding NSiO2-MP interaction with the immune system have been reported. Toll-like receptors (TLR) are involved in host defence as well as autoimmune and inflammatory diseases. The results show that NSiO2-MP up to 100 μg ml−1 do not affect macrophage cell viability after 24 h cell culture. Moreover, NSiO2-MP do not compromise the cell viability of TLR-activated Raw 264.7 cells, for either cell surface TLR (TLR1/TLR2/TLR4/TLR6) or endocytic compartment TLR (TLR3/TLR7/TLR9). Furthermore, Raw 264.7 cells do not respond to NSiO2-MP exposure in terms of IL-6 or IL-10 secretion. NSiO2-MP co-treatment in the presence of TLR ligands does not impair or enhance the secretion of the pro-inflammatory cytokine IL-6 or the regulatory cytokine IL-10. Thus, NSiO2-MP do not affect macrophage polarization towards a pro-inflammatory or immunosuppressive status, representing added value in terms of biocompatibility compared with other SiO2-based micro- and nanoparticles.

December, 2012 | DOI: 10.1016/j.actbio.2012.07.026

Quantum-Mechanical Study on the Aquaions and Hydrolyzed Species of Po(IV), Te(IV), and Bi(III) in Water

Ayala, Regla; Manuel Martinez, Jose; Pappalardo, Rafael R.; Sanchez Marcos, Enrique
Journal of Physical Chemistry B, 116 (2012) 14903-14914


A systematic study of [M(H2O)n(OH)m]q+ complexes of Te(IV) and Bi(III) in solution has been undertaken by means of quantum mechanical calculations. The results have been compared with previous information obtained for the same type of Po(IV) complexes ( J. Phys. Chem. B 2009, 113, 487) to get insight into the similarities and differences among them from a theoretical view. The evolution of the coordination number (n + m) with the degree of hydrolysis (m) for the stable species shows a systematic decrease regardless the ion. A general behavior on the M–O distances when passing from the gas phase to solution, represented by the polarizable continuum model (PCM), is also observed: RM–O values corresponding to water molecules decrease, while those of the hydroxyl groups slightly increase. The hydration numbers of aquaions are between 8 and 9 for the three cations, whereas hydrolyzed species behave differently for Te(IV) and Po(IV) than for Bi(III), which shows a stronger trend to dehydrate with the hydrolysis. On the basis of the semicontinuum solvation model, the hydration Gibbs energies are −800 (exptl −834 kcal/mol), −1580 and −1490 kcal/mol for Bi(III), Te(IV), and Po(IV), respectively. Wave function analysis of M–O and O–H bonds along the complexes has been carried out by means of quantum theory of atoms in molecule (QTAIM). Values of electron density and its Laplacian at bond critical points show different behaviors among the cations in aquaions. An interesting conclusion of the QTAIM analysis is that the prospection of the water O–H bond is more sensitive than the M–O bond to the ion interaction. A global comparison of cation properties in solution supplies a picture where the Po(IV) behavior is between those of Te(IV) and Bi(III), but closer to the first one.

December, 2012 | DOI: 10.1021/jp309439f

Hydrogenation of 2,2,2-trifluoroacetophenone: Molecular insight into the role of solvent in enantioselection

Rosa Pereñiguez; Gianluca Santarossa; Tamas Mallat; Alfons Baiker
Journal of Molecular Catalysis A: Chemical, 365 (2012) 39-49


The unique solvent effect in the enantioselective hydrogenation of α-fluorinated ketones has been investigated in ten different solvents using the  hydrogenation of 2,2,2-trifluoroacetophenone (1) on cinchonine (CN)-modified Pt/Al2O3 as a model reaction. Application of strongly basic solvents – but also increasing hydrogen pressure or conversion – inverted the sense of enantiodifferentiation from (S)-alcohol (expected enantiomer based on the stereochemistry of CN) to (R)-alcohol. The known formation of hemiketals was the origin of the inversion in alcohols. Considering only the non-reacting solvents and low conversions at low pressures, the best correlation was established between the enantiomeric excess and the solvent basicity represented by the H-bond acceptor ability (β). In contrast to former proposals, solvent acidity (α) did not play a significant role. The experimental results are validated by theoretical calculations. The docking of 1 to CN has been investigated in the absence of solvent and also in the presence of toluene and dimethyl formamide. Several competing docking complexes have been isolated that can coexist on the metal surface. Detailed analyses of these complexes show that their stabilities depend on the formation of enantiospecific local interactions between 1, CN, and the platinum surface. The presence of solvent interferes with these interactions, affecting the relative stability of the docking complexes. A correlation between the solvent-induced interactions at molecular level and changes in enantioselectivity is suggested.

December, 2012 | DOI: 10.1016/j.molcata.2012.08.006

Chemical–physical characterization of isolated plant cuticles subjected to low-dose γ-irradiation

Heredia-Guerrero, Jose A; de Lara, Rocio; Dominguez, Eva; Heredia, Antonio; Benavente, Juana; Benitez, Jose J
Chemistry and physics of lipids, 165 (2012) 803-808


Isolated tomato fruit cuticles were subjected to low dose (80 Gy) γ-irradiation, as a potential methodology to prevent harvested fruit and vegetables spoilage. Both irradiated and non-irradiated samples have been morphologically and chemically characterized by scanning electron (SEM), atomic force (AFM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) and X-ray photoelectron (XPS) spectroscopies. Additionally, electrochemical measurements comprising membrane potential and diffusive permeability were carried out to detect modifications in transport properties of the cuticle as the fruit primary protective membrane. It has been found that low dose γ-irradiation causes some textural changes on the surface but no significant chemical modification. Texture modification is found to be due to a partial removal of outermost (epicuticular) waxes which is accompanied by mild changes of electrochemical parameters such as the membrane fixed charge, cation transport number and salt permeability. The modification of such parameters indicates a slight reduction of the barrier properties of the cuticle upon low dose γ-irradiation.

December, 2012 | DOI: 10.1016/j.chemphyslip.2012.10.003

XPS and AES analyses of cerium conversion coatings generated on AA5083 by thermal activation

Sanchez-Amaya, JM; Blanco, G; Garcia-Garcia, FJ; Bethencourt, M; Botana, FJ
Surface and Coatings Technology, 213 (2012) 105-116


This paper describes the deep analysis of cerium conversion coatings developed with thermal activation on AA5083 under optimum processing conditions. Scanning electron microscopy (SEM), electron dispersive spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were employed to study these layers. Ar+ sputtering was also employed to analyse the coatings' core. Although conversion coatings based on Ce salts have been widely characterised in the literature for different aluminium alloys, the coatings developed with thermal activation on Al–Mg alloys have not been previously investigated with these techniques. SEM/EDX studies have demonstrated the existence of a heterogeneous layer formed by a film of aluminium oxide/hydroxide on the matrix as well as a series of dispersed islands of cerium deposited on the cathodic intermetallics. These results have been further confirmed by means of XPS. The XPS and AES results revealed that the outer layer comprises a mixture coating of Ce3 + (70%) and Ce4 + (30%) compounds. Although only Ce3 + compounds were detected at the inner part of the coating, possible reduction of Ce(IV) to Ce(III) due to the Ar+ beam could not be discarded. Obtained results allowed authors to confirm that the cerium conversion coatings developed have a similar structure to those previously reported for other aluminium alloys.

December, 2012 | DOI:

Bulk TiCxN1−x–15%Co cermets obtained by direct spark plasma sintering of mechanochemical synthesized powders

Borrell, A; Salvador, MD; Rocha, VG; Fernandez, A; Aviles, MA; Gotor, FJ
Materials Research Bulletin, 47 (2012) 4487-4490


TiCxN1−x–15 wt.%Co cermets were obtained by a mechanically induced self-sustaining reaction (MSR) and sintered by spark plasma sintering (SPS) technique at different temperatures (1200–1400 °C) for 1 min in vacuum under a uniaxial load of 80 MPa. The evolution of microstructure and mechanical properties was investigated. SPS allowed high densification with limited grain growth at a relatively low temperature. Material sintered at 1300 °C showed a good combination of mechanical properties with Vickers hardness of 17.1 ± 0.5 GPa, fracture toughness of 5.51 ± 0.29 MPa m1/2 and bending strength of 904 ± 12 MPa. Lower sintering temperature resulted in a decrease in bending strength due to poor cohesion between the ceramic and binder phases. An increase in sintering temperature would allow tailoring the cermet microstructure and, therefore, adjusting the Vickers hardness/fracture toughness relation.

December, 2012 | DOI: 10.1016/j.materresbull.2012.09.066

Selective photooxidation of alcohols as test reaction for photocatalytic activity

Lopez-Tenllado, F. J.; Marinas, A.; Urbano, F. J.; Colmenares, J. C.; Hidalgo, M. C.; Marinas, J. M.; Moreno, J. M.
Applied Catalysis B-Environmental, 128 (2012) 150-158


Twenty-four different titania-based systems synthesized through the sol–gel process varying the precursor (titanium isopropoxide or tetrachloride) and/or the ageing conditions (magnetic stirring, ultrasounds, microwave or reflux) were tested for liquid-phase selective photooxidation of 2-butenol (crotyl alcohol) to 2-butenal (crotonaldehyde) and gas-phase selective photooxidation of 2-propanol to acetone. To the best of our knowledge, the former process is suggested for the first time as test reaction for photocatalytic activity. Interestingly, both test reactions (despite having very different reactant/catalyst ratio and contact times) showed quite similar results in terms of influence of the precursor (titanium isopropoxide leading to better results than titanium tetrachloride) and the metals (the presence of iron, palladium or zinc being detrimental to activity whereas zirconium and especially gold improved the results as compared to pure titania). To our mind, these results give validity to both processes as test reactions for a fast screening of catalysts for photocatalytic tranformations. Finally, some gold-containing solids even improved photocatalytic activity of Degussa P25.

November, 2012 | DOI: 10.1016/j.apcatb.2012.02.015

New insights into the synergistic effect in bimetallic-boron catalysts for hydrogen generation: The Co–Ru–B system as a case study

Arzac, G. M.; Rojas, T. C.; Fernandez, A.
Applied Catalysis B-Environmental, 128 (2012) 39-47


Catalysed sodium borohydride hydrolysis is a high-potential method to produce hydrogen for portable applications. Co–B catalysts are the most chosen because they are easily prepared, cheap and efficient. The addition of small amounts of Ru produces a significant enhancement in catalytic activity.

In the present work a series of Co–Ru–B catalysts with variable Ru content was prepared, isolated and characterized. The comprehension of the synergistic effect was achieved trough the incorporation of the nanostructural dimension to the study of surface and bulk chemical states of the involved atoms along the series. It was found that up to 70% (of total metal) atomic content of Ru the catalysts can be considered isostructural to the single Co–B catalyst in the nanoscale. A structural transition occurs in the case of the pure Ru–B material to produce a boron deficient material with higher nanoparticle size. This structural transition together with Co segregation and Ru dispersion play a key role when explaining a [OH−] dependent effect.

The inexistence of borate layers in Ru rich catalysts is suggestive in the research for non deactivating catalysts.

November, 2012 | DOI: 10.1016/j.apcatb.2012.02.013

Ethanol partial photoxidation on Pt/TiO2 catalysts as green route for acetaldehyde synthesis

Murcia, JJ; Hidalgo, MC; Navio, JA; Vaiano, V; Ciambelli, P; Sannino, D
Catalysis Today, 196 (2012) 101-109


Heterogeneous photocatalytic partial oxidation of ethanol was studied over different Pt/TiO2 as an alternative green process for acetaldehyde production.

The catalysts were synthesized through the photodeposition of Pt over sol–gel TiO2 with platinum loads of 0.5 and 1 wt.%. The effect of some experimental conditions during photodeposition, such as deposition time and Pt loading, was investigated. A short deposition time at 0.5 wt.% Pt nominal loading led to small average particle size of platinum (2–3 nm) homogeneously distributed all over the TiO2 surface.

Ethanol partial oxidation was tested in a gas–solid photocatalytic fluidized bed reactor at high illumination efficiency, using different reaction temperatures. Activity results have been correlated with characterization results of the different samples. Platinized samples prepared with short deposition times showed high conversion levels and high selectivity to acetaldehyde. Materials prepared at longer times, 120 min, showed selectivities >98%, although with lower ethanol conversion.

Sample with 1 wt.% Pt loading prepared with 15 min deposition time combined a good compromise between a relevant ethanol conversion and a very high selectivity to acetaldehyde at a selected reaction temperature of 80 °C, with an acetaldehyde yield higher than 80%, which make of this catalyst a good candidate for acetaldehyde production by photocatalysis.

November, 2012 | DOI: 10.1016/j.cattod.2012.02.033