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General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Chabazite, Chabasita, Echange ion, Ion exchange, Cambio iónico, Etat solide, Solid state, Estado sólido, Moteur diesel, Diesel engine, Motor diesel, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réaction one pot, One pot reaction, Reacción one pot, Réduction chimique, Chemical reduction, Reducción química, Synthèse, Synthesis, Síntesis, Zéolite, Zeolite, Zeolita, SAPO-34, Cu/SAPO-34, Emission control, NOx, and Selective catalytic reduction

Cu/SAPO-34 catalysts are synthesized using two methods: solid-state ion exchange (SSIE) and one-pot synthesis. SSIE is conducted by calcining SAPO-34/CuO mixtures at elevated temperatures. For the one-pot synthesis method, Cu-containing chemicals (CuO and CuSO4) are added during gel preparation. A high-temperature calcination step is also needed for this latter method. Catalysts are characterized with surface area/pore volume measurements, temperature programmed reduction (TPR), electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopies, and scanning electron microscopy (SEM). Catalytic properties are examined using standard ammonia selective catalytic reduction (NH3-SCR) and ammonia oxidation reactions. For Cu/SAPO-34 samples prepared by SSIE, Cu presents both as isolated Cu2+ ions and unreacted CuO. The former are highly active and selective in NH3-SCR, while the latter catalyzes a side reaction; notably, the non-selective oxidation of NH3 above 350°C. Using the one-pot method followed by a high-temperature aging treatment, it is possible to form Cu/SAPO-34 samples with predominately isolated Cu2+ ions at low Cu loadings. However at much higher Cu loadings, isolated Cu2+ ions that bind weakly with the CHA framework and CuO clusters also form. These Cu moieties are very active in catalyzing non-selective NH3 oxidation above 350°C. At very low reaction temperature temperatures (<155°C), standard NH3-SCR over Cu/SAPO-34 catalysts appears to be kinetically limited. However at higher temperatures, multiple rate limiting factors are possible.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Métal transition, Transition metal, Metal transición, Adsorption, Adsorción, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur mixte, Mixed catalyst, Catalizador mixto, Gaz à l'eau, Water gas, Gas con agua, Glycérol, Glycerol, Glicerol, Hydrogène, Hydrogen, Hidrógeno, Nanotube multifeuillet, Multiwalled nanotube, Nanotubo pared múltiple, Nickel, Niquel, Palladium, Paladio, Platine, Platinum, Platino, Platinoïde, Platinoid, Platinoide, Protection environnement, Environmental protection, Protección medio ambiente, Reformage, Reforming, Reformación, Sorption, Sorción, Support, Soporte, Bimetallic catalyst, CO2 removal, Platinum-nickel, Platinum-palladium, and Water-gas shift

In this study, multi-walled carbon nanotubes supported Pt and Pt-based bimetallic catalysts were prepared and their catalytic activities were investigated to screen effective and economical catalyst for H2 production in catalytic aqueous phase reforming (CAPR) of glycerol. Nickel promoted Pt catalyst with optimized Ni:Pt molar ratio afforded highest glycerol conversion rate (81.21%) and carbon conversion to gas (15.3%) although hydrogen gasification ratio (7.2%) was poorer than that of noble metals promoted Pt-based bimetallic catalysts. Adding CaO significantly enhanced the fraction and selectivity of H2 over Pt-Ni catalyst and those of CH4 were reduced to a negligible level, which was possibly attributed to the facilitated water-gas shift reaction and inhibited methanation through in-situ CO2 sorption via carbonation. Results suggested that Pt-Ni bimetallic catalysts improved dehydrogenation-decarboxylation and dehydration-hydrogenation reactions, leading to high glycerol conversions. Introducing CaO further favored C-C bond cleavage towards high H2 yield. The catalytic performance can be completely recovered after regenerating the catalyst and adding sacrificial CaO. In terms of reduced consumption of precious metal catalyst, excellent catalyst performance and hydrothermal stability, combination of Pt-Ni bimetallic catalyst and CaO additive was identified as an effective catalytic system for H2 production in CAPR of glycerol.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Atmosphère, Atmosphere, Atmósfera, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Combustion, Combustión, Monoxyde de carbone, Carbon monoxide, Carbono monóxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Zéolite ZSM5, Catalytic activity, Cu-Ce/ZSM-5, and Self-sustained combustion

The Cu/ZSM-5, Ce/ZSM-5 and Cu-Ce/ZSM-5 catalysts were prepared and characterized in this investigation and the catalytic activity of carbon monoxide (CO) combustion under these catalysts was determined by temperature-programmed oxidation. The activity for the CO combustion follows the decreasing order: Cu-Ce/ZSM-5 > Cu/ZSM-5 > Ce/ZSM-5, indicated by lower ignition, light-off, extinction temperature and broader hysteresis determined via both heating and cooling feeding process. The CO adsorbed on the copper sites to form Cu+-CO complexes, monodentate and bidentate carbonates was considered to be the crucial step for CO catalytic combustion. At the CO concentration ≥5 vol.%, the CO self-sustained combustion was achieved over the Cu-Ce/ZSM-5 catalyst. One reason is due to formation of Cu2+ ions incorporated into cerium oxides, which are more reducible than the copper clusters, minicrystals and bulk CuO particles. Another reason is attributable to the formation of Ce4+/Ce3+ redox couple, which facilitates oxygen transport on the catalyst surface.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Composé éthylénique, Ethylenic compound, Compuesto etilénico, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cellulose, Celulosa, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Oléfine, Olefin, Olefina, Protection environnement, Environmental protection, Protección medio ambiente, Pyrolyse, Pyrolysis, Pirólisis, Réaction catalytique, Catalytic reaction, Reacción catalítica, Zéolite ZSM5, Aromatic, Catalytic fast pyrolysis, Isotopic labeling, and Reaction mechanisms

Catalytic pyrolysis over HZSM-5 is an effective method for the conversion of biomass to aromatic hydrocarbons, albeit with low yield and short catalyst lifetimes. Addition of co-reactants rich in carbon and hydrogen can enhance yield and possibly increase catalyst lifetimes by reducing coke formation. Particularly, the catalytic co-pyrolysis of plastic and biomass has been shown to enhance conversion to aromatic hydrocarbons, and also offers a method for productive disposal of waste agricultural plastics. In an effort to determine the origin of the carbon (plastic or biomass) in the products from this catalytic co-pyrolysis, mixtures of uniformly labeled 13C cellulose and non-labeled plastic including polyethylene terephthalate, polypropylene, high density polyethylene, low density polyethylene and polystyrene were subjected to catalytic fast pyrolysis (CFP) at 650°C in the presence of HZSM-5. A micro pyrolyzer coupled with GC/MS (py-GC/MS) advised product distributions and mass spectral data was used to determine the distribution of biogenic carbon and plastic derived carbon in the products. The results demonstrate that aromatic hydrocarbon products formed from the CFP of mixtures of cellulose and plastic are composed mostly of molecules containing carbon of mixed origin. Data on the distribution of 13Cx 12Cy from the products followed in this study show that polyolefin mixtures with cellulose favor the formation of alkyl benzenes that incorporate carbon from both sources. Utilization of aromatic polymers (polystyrene or polyethylene terephthalate) is more selective for formation of naphthalenes with carbon derived from both products. The distribution of various13Cx 12Cy products is used to suggest active mechanisms that result in the formation of the observed products.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Matériaux adsorbants, Adsorbents, Etat colloïdal et états dispersés, Colloidal state and disperse state, Matériaux poreux, Porous materials, Matériau poreux, Porous material, Material poroso, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Charbon actif, Activated carbon, Carbón activado, Conversion, Conversión, Etat transition, Transition state, Estado transitorio, Microporosité, Microporosity, Microporosidad, Oxydation, Oxidation, Oxidación, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Structure pores, Pore structure, Estructura poros, Zéolite, Zeolite, Zeolita, Catalysis, NO oxidation, and Transition states

Anthropogenic NOx emissions from stationary sources to the atmosphere continue to be of concern because of their adverse effects on public health and the environment. An alternative method to conventional selective catalytic reduction to reduce the amount of NOx emissions is oxidation of NO to more soluble NO2 upstream of an absorption device. Zeolites and activated carbon are effective NO oxidation catalysts, but their oxidation mechanisms are not fully understood. Here, zeolites were evaluated as NO oxidation catalysts experimentally and theoretically to identify preferred pore structures for NO conversion to NO2 and to show mechanistic similarities to activated carbon fiber-catalyzed NO oxidation. For the 17 zeolites tested here, steady-state NO conversion is not related to their chemical composition (i.e., Si, Al, or P). However, similar to carbonaceous catalysts, steady-state NO conversion mainly depend on the zeolite's physical properties, including the zeolite's cage size, pore width, and pore volume. Zeolites with maximum free sphere diameter (Dmax) between 4.70 and 6.45 Å, or zeolites with maximum included sphere diameter (Di) between 5.71 and 7.37 Å, derived from experimental results, are most effective for NO oxidation to NO2 regardless of the zeolites' channel-to-cage ratio. A mechanism for NO oxidation proceeding through the [ONOONO] transition state (TS) is described here, challenging the reported mechanism that adsorbed C*-NO3 species are the precursors of NO2 formation. Void spaces with dimensions similar to or slightly larger (i.e., 7 Å width) than the size of the TS (4.46 Å × 4.67 Å × 6.94 Å, derived from TS calculations) are the most effective spaces for NO oxidation due to strengthened van der Waals interaction between the confined TS and pore walls of the zeolite. Criteria for screening effective zeolites for NO oxidation are proposed based on results for the 17 tested zeolites, and 82 of the 206 available zeolite codes are predicted to be effective with high steady-state NO conversion. Consistent physical geometries of zeolite pore sizes (Di = 4.70-6.45 Å or Dmax = 5.71-7.37 A) and activated carbon fiber pore widths (5-7 A) provide convincing evidence that such pore sizes are needed to provide efficient steady-state NO conversion. These results may be extended to other categories of microporous materials to choose the most appropriate material for catalytic NO conversion to NO2.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Composé binaire, Binary compound, Compuesto binario, Composé de métal de transition, Transition element compounds, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Ether, Eter, Hydrogénation, Hydrogenation, Hidrogenación, Oxyde de zirconium, Zirconium oxide, Zirconio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Zéolite, Zeolite, Zeolita, O Zn, ZnO, ZrO2, CO2 hydrogenation, Cu-ZnO-ZrO2 catalysts, Dimethyl ether, and Zeolites

A series of Cu-ZnO-Zr02/H-ZSM5 multifunctional catalysts for the one-step CO2-to-DME hydrogenation reaction was prepared via coprecipitation of methanol catalyst precursors by means of different precipitating agents (i.e., sodium bicarbonate, ammonium carbonate, oxalic acid and urea) in a slurry containing dispersed zeolite particles. The samples were characterized by XRF, XRD, N2 adsorption/desorption isotherms, SEM, N2O-titration, TPR and NH3/CO2 TPD techniques, while the catalytic testing was carried out in a fixed-bed reactor operating at 3.0 MPa, in the TR range 473-513 K and space velocity of 10,000 h-1 (CO2/H2/N2, 3/9/1). The experiments revealed that the preparation methodology significantly affects catalyst properties and hence catalyst activity. The multifunctional catalyst prepared via ammonium carbonate precipitation resulted to be the most active in CO2 conversion, also accomplishing high DME selectivity, with a maximum space-time yield of 0.225 kgDME/kgcat/h. Catalyst characterization disclosed that the strength of basic sites, the ratio between acid and basic sites along with the Cu particle sizes are crucial to achieve maximum catalytic performance, keeping CO selectivity to a minimum value.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Catalyseur, Catalyst, Catalizador, Cinétique, Kinetics, Cinética, Fer, Iron, Hierro, Oxydation, Oxidation, Oxidación, Oxyde d'azote, Nitrogen oxide, Nitrógeno óxido, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réduction chimique, Chemical reduction, Reducción química, Zéolite, Zeolite, Zeolita, Ammonia oxidation, Iron zeolite, Nitrogen oxides, and Selective catalytic reduction

The steady-state kinetics of the selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with ammonia over a commercial iron zeolite catalyst were studied in the temperature range of 250 to 450°C using an integral tubular reactor. Special attention was paid to the stoichiometric ratio of the conversion of ammonia and nitrogen oxides. For this purpose, both systematic SCR measurements at different feed gas compositions and independent studies of the catalytic oxidation of ammonia in the absence of NO and NO2 were carried out. Under all reaction conditions, a considerable deviation from the expected 1:1 stoichiometry was observed. The steady-state kinetics of the reacting system could be described by global Langmuir-Hinshelwood-type rate equations for standard SCR, fast SCR, NO/NO2 equilibrium and NH3 oxidation. For the correct calculation of the ammonia oxidation it was necessary to include two terms. A first one describing the reaction of NH3 with O2, which becomes important at temperatures above 400°C, and a second rate equation which is not only proportional to NH3 and O2 but also to the NO concentration and which is of particular relevance at low reaction temperatures. Additional measurements with different catalyst particle sizes including industrial extrudates could be successfully described with the aid of a reactor model which took film and pore diffusion phenomena into account.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur sur support, Supported catalyst, Catalizador sobre soporte, Cinétique, Kinetics, Cinética, Modélisation, Modeling, Modelización, Protection environnement, Environmental protection, Protección medio ambiente, Répartition spatiale, Spatial distribution, Distribución espacial, Zéolite, Zeolite, Zeolita, Cu zeolites, Kinetic modeling, NH3 SCR, Spaci-MS, and Spatial distribution measurements

In this study, a kinetic model is developed for NH3-SCR over a honeycomb-monolith-supported Cu-zeolites using intra-catalyst axial species distribution measurements. An ammonia TPD experiment, together with micro calorimetry data were used for tuning the ammonia adsorption and desorption properties. The spatial distribution for NO oxidation, NH3 oxidation and NH3 Standard SCR were modeled between 200 and 400 °C. Four-step protocol measurements were employed in order to validate the transient functions of the model. The resulting kinetic model provides good spatiotemporal simulation of the SCR reaction and component reactions throughout the monolith catalyst system.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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 des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Physicochimie de surface, Surface physical chemistry, Echange d'ions, Ion-exchange, Zéolites: préparations et propriétés, Zeolites: preparations and properties, Composé de métal de transition, Transition element compounds, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur sur support, Supported catalyst, Catalizador sobre soporte, Dégradation photochimique, Photochemical degradation, Degradación fotoquímica, In situ, Oxyde de titane, Titanium oxide, Titanio óxido, Protection environnement, Environmental protection, Protección medio ambiente, Zéolite, Zeolite, Zeolita, Catalyseur réutilisable, Reusable catalyst, Dichlorvos, Photodegradation, Titanium dioxide, and Zeolites

Materials based on titania supported on zeolitic matrices (HBETA, HY and HZSM5) were synthesized by in situ generation of TiO2. The supported catalysts characterized by XRD indicate the presence of the anatase phase alone. The materials were also characterized by FTIR. SBET, and UV-VIS DRS. A high TiO2 content produced lower degradation, due to the presence of TiO2 particle aggregates of greater size on the zeolite matrix surface, as evidenced by the calculated crystal size. TiO2/HBETA(20%) presented more activity than TiO2 supported on the other matrices due to higher adsorption of dichlorvos on HBETA. It has more surface area and a lower band gap value too, which makes it more effective. The mineralization degree is lower than the degradation percentage due to the formation of organophosphorous intermediates that are less toxic than the starting material. The complete degradation and mineralization of the pollutant was obtained in 360 and 540 min of reaction with TiO2/HBETA(20%), respectively. This catalyst resulted in degradation percentages close to that of commercial TiO2 P25. The main advantage of supported catalysts is their easy separation and reuse, in this case resulting in a very low activity loss during eight cycles. These materials present suitable properties to be used as catalysts in the photocatalytic treatment of wastewater that contains pesticide dichlorvos in water.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Ammoniac, Ammonia, Amoníaco, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Cinétique, Kinetics, Cinética, Condition hydrothermale, Hydrothermal condition, Condición hidrotermal, Modèle cinétique, Kinetic model, Modelo cinético, Modélisation, Modeling, Modelización, Protection environnement, Environmental protection, Protección medio ambiente, Zéolite, Zeolite, Zeolita, Ammonia SCR, Cu zeolites, Cu/BEA, and Hydrothermal aging

In this study, a kinetic model describing the effect of hydrothermal aging (at 500, 600, 700, 800 and 900 °C) on Cu-zeolites is developed. The model accounts for the impact of hydrothermal aging on key reactions such as ammonia adsorption/desorption, NH3 oxidation, NO oxidation, standard SCR, rapid SCR, and NO2 SCR. In addition, a mechanism for the complex N2O formation were developed. The effect of aging on ammonia adsorption and desorption were established using micro-calorimeter data. Thereafter, an aging factor model was developed containing two aging factors, one related to over-exchanged copper sites and the other to under-exchanged copper sites. This approach worked well for ammonia and NO oxidation up to an aging temperature of 800 °C, whereas for the SCR reactions only to 700 °C. According to UV-vis, fresh and mildly aged catalysts are dominated by copper hydroxyls, while after aging at high temperature copper oxides are observed. We therefore introduce one SCR reaction associated with copper oxides, simultaneously with one SCR reaction associated with ion-exchanged Cu sites and the updated model could describe the experimental findings well. The results from the model also suggest that the standard SCR reaction is more deactivated during aging compared to SCR with NO2 present in the feed. After the 900 °C aging the BEA structure had collapsed, resulting in that several parameters in the model needed to be retuned. The results from this modeling study clearly show how complex the hydro thermal aging is over copper zeolites.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Etat colloïdal et états dispersés, Colloidal state and disperse state, Matériaux poreux, Porous materials, Acide, Acids, Acido, Acidité, Acidity, Acidez, Biomasse, Biomass, Biomasa, Caractérisation, Characterization, Caracterización, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Conversion, Conversión, Glucose, Glucosa, Porosité, Porosity, Porosidad, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Zéolite, Zeolite, Zeolita, Biomass conversion, Fe/HY zeolite catalyst, and Levulinic acid

A series of Fe/HY zeolite catalysts with different FeCl3 weight percent (5, 10 and 15%) on HY zeolite have been synthesized in this study. All the catalysts were characterized by XRD, FESEM, N2 physisorption, FTIR, TGA, NH3-TPD and IR-pyridine. The performance of the Fe/HY catalysts was tested in glucose to levulinic acid transformation. The amount and type of acid sites together with surface area and porosity influenced the catalytic activity. The catalyst with a large surface area, high concentration of active acid sites and appropriate ratio of Brønsted to Lewis acids seemed suitable for levulinic acid production. However, catalyst with excess Lewis acidity converted glucose into humins, but samples with high relative mesopority and low relative microporosity gave a decent levulinic acid yield. Among the catalysts tested, 10% Fe/HY catalyst exhibited the highest catalytic performance with 62% yield at 180 °C in 180 min. The reused catalyst exhibited constant activity for five successive runs. The experimental results demonstrated the potential of Fe/HY catalyst for biomass conversion to levulinic acid under mild process conditions.

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, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Physicochimie de surface, Surface physical chemistry, Propriété physicochimique, Physicochemical properties, Propiedad fisicoquímica, Acide, Acids, Acido, Dégradation, Degradation, Degradación, Ion, Ions, Ión, Sonochimie, Sonochemistry, Sonoquímica, Sulfate, Sulfates, Sulfato, Tension superficielle, Surface tension, Tensión superficial, Ultrason, Ultrasound, Ultrasonido, Defluorination, Perfluorooctanoic acid, Sonochemical, Sulfate ion, and Ultrasonic

This study investigated the effects of sulfate ions on the decomposition of perfluorooctanoic acid (PFOA) by ultrasonic (US) irradiation at various pHs, sulfate doses, powers and temperatures. The removal of PFOA was augmented with an increased sulfate ion concentration, with PFOA being almost completely decomposed in 90 min at 25 °C with a sulfate dose of 117 mM. The two major mechanisms in the sulfate-assisted sonochemical system are the direct destruction of PFOA by cavitation and the indirect destruction of PFOA by sulfate free radicals. The decomposition of PFOA followed pseudo-first-order kinetics and was not influenced by pH. The reaction rate constants decreased with increases in temperature due to decreases in the surface tension of the solution.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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, Aldéhyde, Aldehyde, Aldehído, Adsorption, Adsorción, Aluminium, Aluminio, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Décomposition, Decomposition, Descomposición, Formaldéhyde, Formaldehyde, Formaldehído, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Température ambiante, Room temperature, Temperatura ambiente, Nanoflocon, Nanoflake, Aluminum oxyhydroxide, Catalytic decomposition, Formaldehyde removal, and Pt/AlOOH

Mesoporous AlOOH with deposited Pt (Pt/AlOOH) catalyst was prepared by combining the microemulsion-assisted synthesis of AlOOH nanoflakes with NaBH4-reduction of Pt precursor, and exhibited a remarkable catalytic activity as well as stability for elimination of formaldehyde (HCHO) vapor at room temperature. As compared to Pt deposited on calcined AlOOH (Pt/AlOOH-c), Pt on a commercial Al2O3 (Pt/c-Al2O3) and Pt on P25 (Pt/TiO2), the Pt/AlOOH nanoflakes showed the highest catalytic activity toward decomposition of HCHO at room temperature. The excellent performance of Pt/AlOOH nanoflakes could be attributed to the abundance of surface hydroxyls, high dispersion of Pt nanoparticles, excellent adsorption performance of AlOOH, and its high specific surface area and large pore volume. The mechanism of HCHO decomposition was investigated with respect to the behavior of adsorbed intermediates on Pt/AlOOH surface at room temperature using in situ DRIFTS. The result suggests that surface formate is the main reaction intermediate during the HCHO oxidation and it could be directly oxidized to CO2 in the presence of O2. By taking advantage of high adsorption affinity of AlOOH nanoflakes and excellent catalytic activity of Pt nanoparticles toward HCHO it was possible to design a superior nanostructured catalyst for room temperature decomposition of HCHO. This strategy can be also used to fabricate novel nanostructured catalysts for advanced applications such as environmental remediation.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, 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 des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Physicochimie de surface, Surface physical chemistry, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Colorant, Dyes, Colorante, Interface, Interfase, Minéralisation, Mineralization, Mineralización, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Semiconducteur, Semiconductor materials, Semiconductor(material), Structure, Estructura, CuxS/MOx, Interface control, Optoelectric properties, and Tandem structures

Four mono-component and three tandem structures were prepared by robotic spray pyrolysis deposition using different precursor compositions and deposition temperatures. The structures of the electronic bands and the light generation/injection of the charge carriers trough the tandem layers (CuxS, CuO, SnO2, ZnO, TiO2) were studied using electrical (J-V, photocurrent) and optical (UV-vis transmittance) measurements. The crystalline structures and crystallite sizes were evaluated by X-ray diffraction and the morphologies were studied via atomic force microscopy. The wettability properties and the surface energy were calculated based on contact angle measurements using two liquids with different polarities (glycerol and ethylene glycol). The photocatalytic investigations show that the sample containing TiO2-CuO-CuxS-SnO2 has the highest photo-mineralization efficiency (78% removal of total organic carbon). It was found that copper sulfide compounds increase the photosensitivity properties of the tandem structure especially in vis region of the spectra. The efficiency and kinetics data of the photocatalytic processes were in agreement with the electronic bands alignment, which shows that tandem structures with suitable band energy values and at least one active interface allow high charge carrier mobility and the generation of oxidative species during photocatalysis.

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, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Physicochimie de surface, Surface physical chemistry, Composé binaire, Binary compound, Compuesto binario, Alumine, Alumina, Alúmina, Basse température, Low temperature, Baja temperatura, Interface, Interfase, Métal liquide, Liquid metal, Metal líquido, Oxydation, Oxidation, Oxidación, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Al2O3, Interfacial oxidation, Nano-crystalline layer, and Ultrasonic

Transitional layers at the metal/ceramic interface play an very important role in ceramic joining. In this study, sapphire blocks were ultrasonically dipped in liquid Sn-Zn-Al alloy. It is found that the ultrasound promoted rapid oxidation reaction of aluminum at the Sn-Zn-Al/sapphire interface at 230 °C in the ambient atmosphere, resulting in the formation of a nano-crystalline α-Al2O3 layer (NCAL). In a ~2 nm boundary layer of the NCAL, the lattice matches the sapphire substrate well. Thus, a smooth transition of the lattice from sapphire to metal was formed through the NCAL Ultrasonically soldered sapphire joints were made with Sn-Zn-Al as the filler alloy. Compressive shear strength of the joints reached 43-48 MPa, which is relatively high comparing to other Al2O3 joints made of Sn alloys doped with Ti or Rear Earth elements. Thus, a new mechanism of ultrasonic soldering, i.e. building an oxide transitional layer on the surface of the solid, was revealed. We expect this sonochemical process to be applicable to other metal/oxide systems.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, 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 des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Physicochimie de surface, Surface physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Composé de métal de transition, Transition element compounds, Anatase, Anatasa, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Diffusion, Difusión, Interface, Interfase, Ion, Ions, Ión, Nanoparticule, Nanoparticle, Nanopartícula, Oxydation, Oxidation, Oxidación, Oxyde de titane, Titanium oxide, Titanio óxido, Peroxyde d'hydrogène, Hydrogen peroxide, Peróxido de hydrogeno, Photocatalyse, Photocatalysis, Fotocatálisis, Interface ion diffusion-redox reaction, Ti3+ self-doped TiO2, TiH2, and Visible light photocatalytic

Anatase phase Ti3+ self-doped TiO2-x nanoparticles (NPs) has been successfully synthesized by a simple interface ion diffusion-redox reaction using TiH2 and H2O2 as precursors. The structure, crystallinity, morphology and other properties of the samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The chemical states of Ti in the samples were confirmed by X-ray photoelectron spectra (XPS). Electron spin resonance (ESR) spectra confirm the presence of high concentration of Ti3+ in the bulk and surface of the as-prepared substoichiometric TiO2-x NPs. Composition of the samples was also analyzed by energy dispersive X-ray spectra (EDX) and the results indicate the exist of oxygen vacancies. UV-vis diffuse reflectance spectroscopy (UV-vis DRS) showed that Ti3+ self-doped TiO2-x NPs have a strong absorption between 400 and 800 nm. The formation mechanism of the Ti3+ self-doped TiO2-x NPs was also discussed. Methylene blue (MB) solutions were used as model wastewater to evaluate the visible-light photocatalytic activity of the samples. Under visible light radiation, the samples exhibit excellent ability in the photocatalytic degradation of MB and splitting of water to produce H2. The most active Ti3+ self-doped TiO2-x NPs obtained at 500 C exhibits 68-fold enhancement for the visible light decomposition of MB in comparison to commercial P25 TiO2. The samples also show an excellent cyclic stability of the photocatalytic activity of degrading MB.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, 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, Etat colloïdal et états dispersés, Colloidal state and disperse state, Matériaux poreux, Porous materials, Matériau poreux, Porous material, Material poroso, Adsorbant, Adsorbent, Adsorbente, Adsorption, Adsorción, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Mésoporosité, Mesoporosity, Mesoporosidad, Protection environnement, Environmental protection, Protección medio ambiente, Sorption, Sorción, Structure pores, Pore structure, Estructura poros, Support, Soporte, Tamis moléculaire, Molecular sieve, Tamiz molecular, Technologie bas carbone, 3-D support, CO2 capture, Mesoporous molecular sieve, Molecular basket sorbent, and Polyethylenimine

Three-dimensional (3-D) mesoporous materials including mesocellular siliceous foam (MCF), MSU-J and hexagonal mesoporous silica (HMS) were examined as supports of molecular basket sorbents (3-D MBS) by loading CO2-philic polyethylenimine (PEI). The CO2 sorption performance of the 3-D MBS was evaluated in comparison with the MBS by using MCM-41, SBA-15 and carbon black (CB) as the supports. The effect of PEI loading on the sorption capacity is associated with the sorption temperature and pore structure of the support. At 30 wt% PEI loading, the increase in temperature from 30 to 75 C has a slight and even negative effect on the sorption capacity; while at 65 wt% PEI loading, it has a significant, positive effect. Superior CO2 sorption capacity and sorption rate of 3-D MBS over 2-D and 1-D MBS were observed. MCF-based MBS with 65 wt% PEI loading (PEI(65)/MCF) gave the highest CO2 sorption capacity of 201 mg-CP2/g-sorb. The maximum PEI loading for MCF was up to 80 wt%, which is the largest among the support materials studied in this work, and is related to its largest pore volume. The highest sorption capacity and sorption rate of PEI(65)/MCF are ascribed to its largest pore size and unique 3-D pore structure, which facilitate the CO2 diffusion, promote mass transfer and offer more accessible sorption sites. The present work demonstrates that the 3-D mesoporous solid amine sorbents are more effective for CO2 capture in comparison with 1-D and 2-D materials in terms of higher sorption capacity and faster sorption rate. The pore structure (pore dimension, pore size, pore volume) of the support, PEI loading and temperature are the three key factors that determine the sorption capacity and sorption rate.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, 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, Etat colloïdal et états dispersés, Colloidal state and disperse state, Matériaux poreux, Porous materials, Composé binaire, Binary compound, Compuesto binario, Alumine, Alumina, Alúmina, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur sur support, Supported catalyst, Catalizador sobre soporte, Condition hydrothermale, Hydrothermal condition, Condición hidrotermal, Diffraction RX, X ray diffraction, Difracción RX, Dimension pore, Pore size, Dimensión poro, Effet dimensionnel, Size effect, Efecto dimensional, Epuration effluent gazeux, Flue gas purification, Depuración efluente gaseoso, Gaz échappement, Exhaust gas, Gas escape, In situ, Oxyde d'aluminium, Aluminium oxide, Aluminio óxido, Stabilité thermique, Thermal stability, Estabilidad térmica, Zéolite, Zeolite, Zeolita, Al2O3, Cu/Al2O3 interaction, Cu/zeolite SCR catalysts, Hydrothermal stability, In situ XRD, and Zeolite pore size effect

A comparison study on the hydrothermal stability of Cu SCR catalysts supported on an 8-ring small pore chabazite and a 12-ring large pore beta zeolite was performed to understand why small pore zeolite supported Cu catalysts are in general hydrothermally more stable than medium pore or large pore zeolite supported Cu catalysts and how different pore sizes affect the hydrothermal stability of the catalysts. In situ XRD hydrothermal experiments show that, even though the parent chabazite and beta zeolites have comparable hydrothermal stability and both can maintain their zeolite framework structure after a 900 C hydrothermal exposure, the presence of Cu in the Cu/beta catalyst accelerates the collapse of the BEA framework structure at temperatures above 800 °C whereas Cu in the Cu/chabazite catalyst has little effect on the CHA framework structure. The loss of beta zeolite framework structure is due to a detrimental Cu/Al2O3 interaction. It is proposed that the constricting dimensions of the small openings in a small pore zeolite can hinder the destructive Cu/Al2O3 interaction as well as the zeolite dealumination process, hence significantly improving the hydrothermal stability of the small pore zeolite supported Cu catalyst.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie de surface, Surface physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Gels colloïdaux. Sols colloïdaux, Colloidal gels. Colloidal sols, Article synthèse, Review, Artículo síntesis, Eau, Water, Agua, Hydratation, Hydration, Hidratación, Interface, Interfase, Ion, Ions, Ión, Lanthanide, Lantánido, Lipide, Lipids, Lípido, Matière molle, Soft matter, Materia suave, Cation hydration and coordination, Hofmeister series, Lanthanides, Soft matter interfaces, and Specific ion effects

At charged surfaces bound ions reduce the repulsive electrostatic forces, while dissociated ions control the osmotic pressure in colloidal systems. For systems charged through ionic adsorption on the other hand, the adsorbed ions determine the charging boundary condition and colloidal interactions. Soft-matter interfaces have considerable flexibility and compressibility, hence ionic adsorption at such interfaces may generate new phenomena when (a) the ions compete with the lipid or polymeric components for water of hydration, or (b) position themselves at the polar-nonpolar interface and modify its structure. We review some recent advances on the understanding of specific ion effects from this perspective, and provide some unpublished illustrative examples involving soft flexible interfaces. We propose an extension of the chaotropic series to include disruptors of soft matter, which may act as cosurfactants or even as hydrotropes. We also examine the effects of coordinating ligands on specific ion adsorption at soft interfaces, using lanthanides as test cations, and discuss how such effects may be used to change the affinities between ions and interfaces in controlled ways.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Physicochimie de surface, Surface physical chemistry, Interface gaz-liquide et liquide-liquide, Gas-liquid interface and liquid-liquid interface, Interface solide-liquide, Solid-liquid interface, Propriété physicochimique, Physicochemical properties, Propiedad fisicoquímica, Article synthèse, Review, Artículo síntesis, Etalement, Spreading, Escalonamiento, Gel polymère, Polymer gels, Goutte, Drop, Gota, Interface gaz liquide, Gas liquid interface, Interfase gas líquido, Interface liquide liquide, Liquid liquid interface, Interfase líquido líquido, Interface liquide solide, Liquid solid interface, Interfase líquido sólido, Liquide, Liquid, Líquido, Tension superficielle, Surface tension, Tensión superficial, Liquid surfaces, Marangoni flow, and Self-motility

Surface tension gradients are at the origin of the self-motion and deformation of millimeter-sized floating objects. For (quasi-)non-deformable systems, like solids and gels, the motion-mode is mainly controlled by the shape of the object and by the way the surface active propellant is released on the surrounding surface. Two situations are reviewed In the first one, the propellant container is the propelled object itself, while in the second case the propellant is placed in a reservoir embarked on a manufactured float. The properties and efficiency of these solid systems are examined and compared for different geometries. They are also compared with the intriguing properties of self-motile liquid lenses/drops which present several additional abilities (spontaneous deformation to adapt their shape to the selected motion-mode, presence of complex fluid flows outside and inside the drops, partial break-ups...). Three mechanisms leading to spontaneous motility have been identified in the literature. Among them two are more largely exemplified in the following as they involve a contribution of the Marangoni driven spreading effect, leading to velocities on the cm/s scale. The main theoretical tools usually used for describing the motion and deformation of such self-propelled systems are also reviewed.