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General chemistry, physical chemistry, Chimie générale, chimie physique, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Méthodes électrochimiques, Electrochemical methods, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Matériaux composites, Composites, Activité catalytique, Catalyst activity, Actividad catalítica, Allylique amine polymère, Allylic amine polymer, Alílica amina polímero, Autoassemblage, Self assembly, Autoensamble, Couche autoassemblée, Self-assembled layer, Capa autoensamblada, Détecteur électrochimique, Electrochemical detector, Detector electroquímico, Electrocatalyse, Electrocatalysis, Electrocatálisis, Ethylèneimine polymère, Polyethylene imine, Etilenoimina polímero, Etude comparative, Comparative study, Estudio comparativo, Etude expérimentale, Experimental study, Estudio experimental, Fabrication, Manufacturing, Fabricación, Hexacyanoferrate, Hexacyanoferrates, Hexacianoferrato, Multicouche, Multiple layer, Capa múltiple, Nanocomposite, Nanocompuesto, Peroxyde d'hydrogène, Hydrogen peroxide, Peróxido de hydrogeno, Polymère conducteur, Conducting polymers, Polymère dopé, Doped polymer, Polímero dopado, Polymère ramifié, Branched polymer, Polímero ramificado, Polyélectrolyte, Polyelectrolyte, Polielectrolito, Propriété électrochimique, Electrochemical properties, Propiedad electroquímica, Réduction chimique, Chemical reduction, Reducción química, Styrènesulfonate polymère, Styrenesulfonate polymer, Estireno sulfonato polímero, Thiophène dérivé polymère, Thiophene derivative polymer, Tiofeno derivado polímero, Voltammétrie cyclique, Cyclic voltammetry, Voltametría cíclica, Ethylènedioxythiophène polymère, Conductive polymer, Electrochemical sensors, Nanocomposite films, and Prussian blue nanoparticles

Prussian blue (PB) nanoparticles were immobilized in polyelectrolyte (PE) multilayers of various compositions and thickness. Films containing nanoparticles and poly(allylamine hydrochloride) (PAH) were formed using the layer-by-layer adsorption method. A layer of branched poly(ethyleneimine) (PEI) was used to anchor the multilayer structure at the surface of a gold electrode. The films exhibited electroactive properties, increasing with the number of deposited PB layers. The properties of PEI/(PB/PAH)n multilayers were then compared with the ones containing additionally the conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). We found that the addition of the conductive, water-soluble polymer enhances the electroactive properties of the multilayer films. It also increased sensitivity of the multilayer-covered electrodes for electrochemical detection of hydrogen peroxide.

General chemistry, physical chemistry, Chimie générale, chimie physique, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Cristallisation, Crystallization, Caprolactone polymère, Polycaprolactone, Caprolactona polímero, Cinétique, Kinetics, Cinética, Condition non isotherme, Non isothermal condition, Condición no isoterma, Cristallisation isotherme, Isothermal crystallization, Cristalización isotérmica, Cristallisation état fondu, Melt crystallization, Cristalización estado fundido, Effet composition, Composition effect, Efecto composición, Ethylène oxyde polymère, Ethylene oxide polymer, Etileno óxido polímero, Etude expérimentale, Experimental study, Estudio experimental, Mécanisme, Mechanism, Mecanismo, Mélange polymère, Polymer blends, Nucléation, Nucleation, Nucleación, Séparation phase, Phase separation, Separación fase, Fluctuation-assisted crystallization, Interface-assisted crystallization, Liquid-liquid phase separation, and PEO/PCL blend

The nucleation and crystallization of poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL) in the PEO/ PCL blends have been investigated by means of optical microscopy (OM) and differential scanning calorimetry (DSC). During the isothermal or nonisothermal crystallization process, when the adjacent PEO is in the molten state, PCL nucleation preferentially occurs at the PEO and PCL interface; after the crystallization of the adjacent PEO, much more PCL nuclei form on the surface of the PEO crystal. However, PEO crystallizes normally and no interfacial nucleation occurs in the blend. The concentration fluctuation caused by liquid-liquid phase separation (LLPS) induces the motion of PEO and PCL chains through interdiffusion and possible orientation of chain segments. The oriented PEO chain segments can assist PCL nucleation, and the heterogeneous nucleation ability of PEO increases with the orientation of PEO chains. Oriented PCL chain segments have no heterogeneous nucleation ability on PEO. It is postulated that the interfacial nucleation of PCL in the PEO/PCL blend follows the combination offluctuation-assisted crystallization and interface-assisted crystallization mechanisms.

General chemistry, physical chemistry, Chimie générale, chimie physique, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Propriétés de surface, Surface properties, Adipate copolymère, Adipate copolymer, Adipato copolímero, Caprolactone copolymère, Caprolactone copolymer, Caprolactona copolímero, Caprolactone polymère, Polycaprolactone, Caprolactona polímero, Copolymère aliphatique, Aliphatic copolymer, Copolímero alifático, Copolymère biséquencé, Diblock copolymer, Copolímero bisecuencia, Copolymère greffé, Graft copolymer, Copolímero injertado, Copolymère linéaire, Linear copolymer, Copolímero lineal, Couche Langmuir Blodgett, Langmuir Blodgett layer, Capa Langmuir Blodgett, Cristallisation isotherme, Isothermal crystallization, Cristalización isotérmica, Ethylène oxyde copolymère, Ethylene oxide copolymer, Etileno óxido copolímero, Etude comparative, Comparative study, Estudio comparativo, Etude expérimentale, Experimental study, Estudio experimental, Interface air eau, Air water interface, Interfase aire agua, Terpolymère, Terpolymer, Terpolímero, Topographie surface, Surface topography, Greffon biséquencé, Isotherme compression, Amphiphilic graft copolymer, Crystallization, Langmuir trough, Langmuir-Blodgett films, and PCL

The behavior of crystallizable poly(ε-caprolactone) (PCL) and poly(ε-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) is studied at the air/water interface prior and after grafting to an amorphous poly(glycerol adipate) (PGA) backbone (PGA-g-PCL, PGA-g-(PCL-b-PEO)). Langmuir isotherms are measured and the structure formation in the monolayers on the water surface is followed by Brewster angle microscopy (BAM) and in Langmuir-Blodgett films after a transfer to silicon substrates by atomic force microscopy (AFM). It is observed that PGA-g-PCL forms significantly smaller crystals on the water surface and has smaller crystallization rate compared to PCL homopolymers of identical molar masses as the grafted chains. In contrast to crystals formed by linear PCL, the crystals formed by grafted PCL in PGA-g-PCL do not melt (readsorb at the water surface) in an expansion cycle on the Langmuir trough. Additionally, increasing the subphase temperature at constant surface area significantly above the melting point of linear PCL in bulk results in the formation of a mesophase, and it does lead to the disappearance of crystals. The isotherms of PGA-g-(PCL-b-PEO) show a transition at the surface pressure of ~ 10 mN/m. This is related to the fact that PEO chains leave the water surface and submerge into the subphase and/or the crystallization of PCL chains. The monolayer collapse appears in an extended plateau region starting at π values of ~30 mN/m. AFM images of Langmuir-Blodgett films reveal that PCL chains in PGA-g-PCL and PGA-g-(PCL-b-PEO) form lamellar crystals with a disk-shape and interconnected platelets, respectively.

General chemistry, physical chemistry, Chimie générale, chimie physique, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Gels colloïdaux. Sols colloïdaux, Colloidal gels. Colloidal sols, Composé de métal de transition, Transition element compounds, Adhérence, Adhesion, Adherencia, Bactéricidie, Bactericidal effect, Bactericidia, Caractérisation, Characterization, Caracterización, Couche mince, Thin film, Capa fina, Effet solvant, Solvent effect, Efecto solvente, Film, Película, Nanostructure, Nanoestructura, Oxyde de nickel, Nickel oxide, Níquel óxido, Procédé sol gel, Sol gel process, Procedimiento sol gel, Préparation, Preparation, Preparación, Anitibacterial activity, NiO, Sol-gel preparation, and Structural characterization

This study presents the characterization and antibacterial activity of nanostructure NiO films synthesized by sol-gel dip coating method using solvents of different polarities and viscosities without any catalysts, templates or surfactants. Methanol, 1,4-butanediol, ethanol, and 2-propanol were used as solvent. The antibacterial activity was tested against two common foodborne pathogenic bacteria Staphylococcus aureus (ATCC 25922) and Escherichia coli (ATCC 29213) using the so-called antibacterial drop test. X-ray diffraction, scanning electron microscopy, atomic force microscopy, UV-vis spectroscopy and static contact angles test were used to analysis the structure and morphology character, surface topography, optical property and surface wettability of different coatings, respectively. The characterization results showed different preferred crystallographic orientations, particle sizes, surface properties and optical band gap of NiO films according to the solvent physicochemical properties. The antibacterial efficiencies were affected by the physiological status of the bacterial cells and degree of bacteria adherence, morphologies and crystal growth habits, surface and optical properties of NiO samples.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé éthylénique, Ethylenic compound, Compuesto etilénico, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Conversion, Conversión, Oléfine, Olefin, Olefina, Réaction catalytique, Catalytic reaction, Reacción catalítica, Synthèse, Synthesis, Síntesis, SAPO-34, Cetyltrimethyl ammonium bromide, Chloromethane, Hierarchical SAPO-34, and Light olefins

Hierarchical SAPO-34 molecular sieve was successfully synthesized by hydrothermal crystallization method with cetyltrimethyl ammonium bromide as mesoporous generating agent. The influence of different addition amounts of CTAB on the crystalline structures, morphology features, textural properties and acidity of hierarchical SAPO-34 catalysts were characterized by XRD, SEM, BET and NH3-TPD techniques. The results exhibit that the crystal size, mesoporous structure and the total acid amounts of hierarchical SAPO-34 are affected greatly by the molar ratio of CTAB/Al2O3. The selectivity of light olefins (ethane and propylene) can achieve 80 % for all SAPO-34 samples tested in the conversion of chloromethane to light olefins. Compared with the conventional SAPO-34, the hierarchical SAPO-34 samples show better catalytic stability and less carbon deposit in this conversion due to the reduction in total acid sites and the increasing mesopore volume.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé binaire, Binary compound, Compuesto binario, Métal transition, Transition metal, Metal transición, Alumine, Alumina, Alúmina, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Composé de métal de transition, Transition element compounds, Cuivre, Copper, Cobre, Diffraction RX, X ray diffraction, Difracción RX, In situ, Modélisation, Modeling, Modelización, Monoxyde de carbone, Carbon monoxide, Carbono monóxido, Oxydation, Oxidation, Oxidación, Oxyde d'aluminium, Aluminium oxide, Aluminio óxido, Oxyde de cérium, Cerium oxide, Cerio óxido, Solution solide, Solid solution, Solución sólida, Spectrométrie EXAFS, EXAFS spectrometry, Espectrometría EXAFS, Al2O3, CeO2, CuO, EXAFS modeling, In situ XRD, Solid solution of copper in ceria, Total oxidation, and VOCs

Different types of copper oxide in CuO-CeO2/ Al2O3 were investigated structurally and catalytically. Standard preparation lead to the presence of CuO monocrystals and Ce1-xCuxO2-x as evidenced by XRD, HRTEM and EDX. Washing with nitric acid removed the monocrystals, while leaving the Ce1-xCuxO2-x solid solution. The Fourier transformed Cu K patterns for the HNO3-washed catalyst showed a diminished second Cu shell, characteristic for Ce1-xCuxO2-x as well as for X-ray amorphous nano-sized CuAl2O4 spinel phase. XANES analysis and first shell Cu fitting confirmed this CuAl2O4 like structure outside Ce1-xCuxO2-x. By modeling the Ce K EXAFS signal in the washed sample, the amount of Cu in Ce1-xCuxO2-x was determined to be 18 ± 6 %. Total oxidation of CO and C3H8 as model reactions showed little difference in activity between non-washed and washed CuO-CeO2/Al2O3, indicating that CuO monocrystals were hardly active at temperatures below 450 °C. XRD performed in situ during TPR and TPO showed that CeO2 in Ce1-xCuxO2-x added to the redox capacity of both CuO-CeO2/Al2O3 samples as it was partially reduced at 300 °C. At higher temperatures, the CuO monocrystals also participated in reaction, leading to a higher activity for the oxidation of CH4.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Composé de métal de transition, Transition element compounds, Mécanisme, Mechanism, Mecanismo, Nanotube carbone, Carbon nanotubes, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Oxyde de cuivre, Copper oxide, Cobre óxido, Réduction chimique, Chemical reduction, Reducción química, CuO, Carbon nanotube, and NO reduction

Carbon nanotube (CNT) supported copper oxide catalysts were prepared, and the morphology and structure of the catalyst were characterized by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and temperature-programmed desorption experiments. The CuO/CNT catalysts demonstrated high catalytic activities during the selective catalytic reduction (SCR) of NO with NH3 over a temperature range of 150-250 °C. The amount of NH3 adsorbed on the catalyst surface was greater than that of NO or NO + O2 adsorbed on the catalyst surface. These results suggest that the SCR reaction might proceed on the surface of the CuO/CNT catalysts and occur between the adsorbed ammonia and gas phase NO or weakly adsorbed NO. The CuO/CNT catalysts exhibited good stability at low temperatures, which makes them suitable for potential applications in industry.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé éthylénique, Ethylenic compound, Compuesto etilénico, Acide, Acids, Acido, Acétal, Acetal, Acétalisation, Acetalization, Acetalización, Catalyse homogène, Homogeneous catalysis, Catálisis homogénea, Chimie verte, Green chemistry, Química verde, Complexe de métal de transition, Transition element complexes, Complexe de rhodium, Rhodium complex, Rodio complejo, Hydroformylation, Hidroformilación, Mécanisme, Mechanism, Mecanismo, Oléfine, Olefin, Olefina, Platinoïde Complexe, Platinoid Complexes, Platinoide Complejo, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, and Reacción catalítica

The acetal formation mechanism under acid-free Rh-catalyzed hydroformylation-acetalization condition has been studied using different rhodium catalyst precursors in MeOH. In the absence of added acidic co-catalyst, the acetalization is catalyzed by the H+ formed in situ under hydroformylation condition, and Rh active site on Rh-phosphine catalyst did not exhibit catalytic activity for acetalization. Whether H+ can be generated in situ is related with the structure of rhodium catalyst precursor. Under hydroformylation condition, added Brønsted acids as co-catalysts can improve acetalization efficiency, but the H+ concentration in the system should not be excessively high to avoid the acid-induced inhibition for hydroformylation.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Métal transition, Transition metal, Metal transición, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dimension particule, Particle size, Dimensión partícula, Effet dimensionnel, Size effect, Efecto dimensional, Forme particule, Particle shape, Forma partícula, Morphologie, Morphology, Morfología, Méthode fonctionnelle densité, Density functional method, Nanoparticule, Nanoparticle, Nanopartícula, Oxygène, Oxygen, Oxígeno, Platine, Platinum, Platino, Réduction chimique, Chemical reduction, Reducción química, Density functional theory, Oxygen reduction reaction, Particle size effect, and Platinum nanoparticle

We present first principle investigation of the influence of platinum nanoparticle shape and size on the oxygen reduction reaction activity. We compare the activities of nanoparticles with specific shapes (tetrahedron, octahedron, cube and truncated octahedron) with that of equilibrium particle shape at 0.9 V. Furthermore, the influence of support is assessed by looking at the particles with and without support interactions. The equilibrium shape is determined by calculating the changes in surface energies with potential for low-index platinum facets; (111), (100) and (110). This has been done by explicitly taking the coverage of oxygenated species into account. A kinetic model derived from counting the number of sites shows that the theoretical activity obtained for equilibrium particle fits well with experimental data. Particles with ∼ 3 nm diameter are found to possess the highest activity.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Métal transition, Transition metal, Metal transición, Platinoïde, Platinoid, Platinoide, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Ruthénium, Ruthenium, Rutenio, Support, Soporte, Synthèse, Synthesis, Síntesis, Ammonia synthesis, Graphitised support, Promoted ruthenium catalyst, and Surface reorientation

In the 1970s BP started developing a new catalyst for ammonia synthesis which in final form comprises ruthenium, two promoters and a graphitised carbon support. This became the first new catalyst for ammonia synthesis to be commercialised since Fritz Haber's promoted iron catalyst. The catalyst is commercialised in the KBR Advanced Ammonia Process (KAAP). We describe the development of the catalyst, starting in the 1960s with studies to elucidate the mechanism of selective hydrogenation catalysts using nickel single crystals and LEED. These identified a phenomenon dubbed surface reorientation, in which an adsorbate such as sulphur causes the structure of the surface monolayer of a metal to change e.g. from fcc [111] to [100]. These ideas led to discovery of an active platinum/alkali metal/carbon catalyst for the dehydrocyclisation of hexane. That catalyst was not commercial, but it led in turn to the identification of highly active ruthenium/alkali metal/carbon catalysts for ammonia synthesis. The best new catalyst is about 20 times more active than a commercial Haber catalyst. The special carbon support is mesoporous and graphitic. Scale up of catalyst production and testing are described briefly, as are some process considerations.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie de surface, Surface physical chemistry, Echange d'ions, Ion-exchange, Zéolites: préparations et propriétés, Zeolites: preparations and properties, Métal transition, Transition metal, Metal transición, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cuivre, Copper, Cobre, Nitrate d'ammonium, Ammonium nitrate, Amonio nitrato, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Protoxyde d'azote, Nitrogen protoxide, Nitrógeno protóxido, Zéolite, Zeolite, Zeolita, Cu-BEA, Fast SCR, N2O, NH3-SCR, NO2-SCR, and NO/NO2 feed ratio

In this study we examine the NO/NO2-NH3-SCR system over Cu-BEA with varying Cu loading. Significantly higher selective catalytic reduction (SCR) activity is observed at low temperature on highly loaded copper samples, whereas the reverse trend is noticed at high temperature. The N2O formation is substantially increased over over-exchanged Cu sites, where Cu co-ordinate to one Al and charge-balanced with one OH-group. This is also the case for NO2 reaction with NH3 to produce NO. Using transient experiments the formation/decomposition of ammonium nitrate species are examined. The decomposition depends on the temperature, the sequence of the feed as well as the type of copper species present.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Sciences appliquees, Applied sciences, Energie, Energy, Combustibles, Fuels, Combustibles de remplacement. Production et utilisation, Alternative fuels. Production and utilization, Hydrogène, Hydrogen, Composé binaire, Binary compound, Compuesto binario, Métal transition, Transition metal, Metal transición, Alumine, Alumina, Alúmina, Argent, Silver, Plata, Baryum, Barium, Bario, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur sur support, Supported catalyst, Catalizador sobre soporte, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Oxyde de baryum, Barium oxide, Bario óxido, Piège, Trap, Trampa, Platine, Platinum, Platino, Stockage hydrogène, Hydrogen storage, Al2O3, H2 effect, Lean NOx adsorber, NO2 formation, Passive NOx trap, Pt/BaO/Al2O3, and Silver/alumina

Addition of hydrogen significantly increases the amount of stored nitrogen oxides (NOx) over Pt/Ba/ Al2O3 at 100°C and Ag/Al2O3 between 100 and 200 °C. This increase is unique for hydrogen as reductant. A higher apparent NOx storage capacity is also observed by simultaneous reduction of NO in a selective catalytic reduction (SCR) reaction, where, however, the conversion in H2-SCR is <10 % in this study.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Composé binaire, Binary compound, Compuesto binario, Métal transition, Transition metal, Metal transición, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Composé de lanthanide, Lanthanide compound, Lantánido compuesto, Composé de métal de transition, Transition element compounds, Cuivre, Copper, Cobre, Dynamique, Dynamics, Dinámica, Hystérésis, Hysteresis, Histéresis, Oxyde de cérium, Cerium oxide, Cerio óxido, CeO2, CuO, Ceria, Copper-ceria interaction, Pd-PdO and CuO-Cu2O hysteresis, and TPO

CuO supported on ceria and alumina is prepared by incipient wetness impregnation and its redox behavior is investigated by means of XRD, XPS and TPO experiments. CuO on ZrO2 and on ceria-zirconia are also synthesized for comparison. The support plays a major role on the dynamics of CuO-Cu2O transformation. On Al2O3 the formation of CuAl2O4 inhibits any oxygen exchange during TPO experiments, while on ceria, zirconia and ceria-zirconia supported catalysts CuO decomposition and re-oxidation take place with a hysteresis similar to that observed for Pd-PdO transformation. On CeO2 the hysteresis is significantly reduced, indicating a strong effect of ceria on CuO-Cu2O redox cycle.

General chemistry, physical chemistry, Chimie générale, chimie physique, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Gels colloïdaux. Sols colloïdaux, Colloidal gels. Colloidal sols, Matériaux poreux, Porous materials, Composé binaire, Binary compound, Compuesto binario, Agent surface, Surfactant, Agente superficie, Alumine, Alumina, Alúmina, Matériau poreux, Porous material, Material poroso, Mésoporosité, Mesoporosity, Mesoporosidad, Procédé sol gel, Sol gel process, Procedimiento sol gel, Rétraction, Retraction, Retracción, Structure, Estructura, Agent structurant, Template, Al2O3, Dual soft templates, Gel retraction, Porous alumina structures, Sol-gel, and Surfactants

This work presents a method that enables the synthesis of porous alumina in the presence of different types of surfactant. The method is based on a sol―gel transition, using surfactants and droplets of a nonpolar phase as templates. The main purpose was to establish a relationship between the templates and the resulting pore structure. The results show that depending on the type of surfactant used (ionic or nonionic), materials presenting variations in the pore family distribution, X-ray powder diffraction patterns and sample morphology were formed. During the synthesis of these alumina samples, the drying step caused loss of the porous structures, so the shrinkage due to different types of surfactants was evaluated.

General chemistry, physical chemistry, Chimie générale, chimie physique, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Etat colloïdal et états dispersés, Colloidal state and disperse state, Gels colloïdaux. Sols colloïdaux, Colloidal gels. Colloidal sols, Matériaux poreux, Porous materials, Composé binaire, Binary compound, Compuesto binario, Matériau poreux, Porous material, Material poroso, Acide, Acids, Acido, Aérogel, Aerogel, Aerógel, Carbure, Carbides, Carburo, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Composé de métal de transition, Transition element compounds, Etude comparative, Comparative study, Estudio comparativo, Procédé sol gel, Sol gel process, Procedimiento sol gel, Réaction catalytique, Catalytic reaction, Reacción catalítica, Xérogel, Xerogel, Zircone, Zirconia, Zircona, ZrO2, Carbide, and Heteropolytungstic acid

Zirconia doped by heteropolytungstic acid HPW have been synthesized by sol―gel method using two drying techniques of the solvent evacuation. Samples were analyzed with adsorption―desorption of N2 at 77 K, and the aerogel catalyst was found to exhibit a higher surface area and a higher average pore diameter compared to xerogel. XRD results show that aerogel develops ZrO2 tetragonal phase, whereas xerogel is amorphous. The thermal analysis studies show that the aerogel's thermal stability is better than the xerogel one. The catalytic behavior of the aerogel and xerogel toward the nature of the isomerization products probably depends on the acidity and the presence of carbide species. This has been explained by XPS and isopropanol dehydration reaction. In fact, the deconvolution aerogel's Cls bands reveals the presence of four carbon species assigned to C―C, C=O, C―O and carbide species.

General chemistry, physical chemistry, Chimie générale, chimie physique, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Gels colloïdaux. Sols colloïdaux, Colloidal gels. Colloidal sols, Sciences appliquees, Applied sciences, Energie, Energy, Energie naturelle, Natural energy, Energie solaire, Solar energy, Conversion photovoltaïque, Photovoltaic conversion, Cellules solaires. Cellules photoélectrochimiques, Solar cells. Photoelectrochemical cells, Cellule solaire, Solar cell, Célula solar, Composé de métal de transition, Transition element compounds, Nanofil, Nanowires, Nanotube, Nanotubo, Procédé sol gel, Sol gel process, Procedimiento sol gel, Pyrite, Pirita, Rayonnement solaire, Solar radiation, Radiación solar, Sulfure de fer, Iron sulfide, Hierro sulfuro, Synthèse, Synthesis, Síntesis, Agent structurant, Template, Band gaps, FeS2, and Sol―gel

Highly ordered iron pyrite (FeS2) nanowires and nanotubes arrays have been fabricated by using sol―gel method with AAO templates. The prepared nanowires and nanotubes have uniform lengths and 200 nm diameters. Their crystal phase was identified as cubic FeS2 by using X-ray diffraction, Raman spectroscopy, high-resolution transmission electron microscopy and selected-area electron diffraction pattern. The direct optical band gaps of the as-prepared FeS2 nanowires were 0.98 and 1.23 eV, respectively, indicating their suitability for photovoltaic application.