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In this paper, a heteropolyacid catalyst VPO-Cr-PEG/TiO2 was developed and the low temperature de-NOx performance of catalyst was studied. The experimental results showed that the de-NOx efficiency reached over 98% at the low temperature of 150–350 °C. The catalyst exhibited excellent sulfur and water resistance in the presence of 1000 ppm SO2 and 8 vol% H2O. In the presence of polyethylene glycol (PEG), the crystal surface energy of the catalyst decreased, and (VO)2P2O7 was the main active crystal phase of the catalyst. The selective catalytic reduction of NOx by NH3 over VP(1/5)O-Cr-PEG/TiO2 catalyst simultaneously followed the Langmuir-Hinshelwood and Eley-Rideal mechanisms.

Catalysts 11(11), 1325 (1-15) (2021). doi:10.3390/catal11111325, This study presents information about crystal imperfections in the main phase of industrial vanadium phosphorous oxide catalysts that are used to catalyze the oxidation of n-butane to maleic anhydride, being an important intermediate in the chemical industry. The mechanism of this reaction is still debated, and the catalytically active and selective surface centers have not yet been identified. The results presented are based on X-ray diffraction data obtained by both laboratory-scale and synchrotron powder diffraction experiments, as well as laboratory-scale single-crystal diffraction experiments. It has been proven that pronounced Bragg reflection broadening effects found in laboratory-scale powder diffraction patterns of industrial VPO catalysts are real and not due to an insufficient 2-�� resolution of the apparatus. In the framework of this work, a powder diffraction full profile fitting strategy was developed using the TOPAS software, which was applied to analyze the X-ray diffraction data of four differently activated industrial catalyst samples, originating from one batch after they had been catalytically tested. It was found that the reflection broadening is mainly caused by an anisotropic crystal size, which results in platelet-shaped crystallites of vanadyl pyrophosphate. A further contribution to the reflex broadening, especially for (111), was found to be a result of stacking faults perpendicular to the a direction in the crystal structure of vanadyl pyrophosphate. These results were used to elaborate on possible correlations between structural proxies and catalytic performance. A direct correlation between the extension of coherently scattering domains in the z direction and the catalyst���s selectivity could be proven, whereas the activity turned out to be dependent on the crystallite shape. Regarding the phase contents, it could be shown that sample catalysts containing a higher amount of ��-VO(PO$_3$)$_2$ showed increased catalytic activity., Published by MDPI, Basel

62 p., El presente trabajo, consiste en el desarrollo del análisis arquitectónico y audiovisual de distintos videoclips, pertenecientes a una nueva generación de artistas, conocida como género urbano, buscando como objetivo profundizar en la relación entre la arquitectura contemporánea y la producción musical urbana. Para ellos, se seleccionarán distintas obras audiovisuales, situadas concretamente en España, y consideradas las más representativas a la hora de vincular estos dos fenómenos artísticos. Para contextualizar el tema, se realizará un estudio sobre la historia del videoclip, esencialmente su tratamiento espacial, así como de su interesante vinculación con la arquitectura, a lo largo de la evolución del desarrollo tecnológico. También se establecerán las bases y orígenes del género musical urbano, y su estrecha relación política y social, para culminar con la comprensión de distintos casos de estudio. Además, se tratará de generar, a partir de una base teórica lo suficientemente sólida, la relación entre el espacio urbano y la arquitectura mediante esta nueva ola de artistas, que configuran el resultado e un tejido económico, social y político del mundo capitalista postindustrial., The present work will be developed with the objective of analysed the architecture and audiovisual content of diferente videoclips, belonging to a new generation of artista, who belong to the urban genre. The main objective is to go in depth in the relationship between contemporary architecture and urban music production. To achieve this, different audiovisual works are selected, specifically located in Spain, which are considered the most representative when it comes to link the artistic phenomena mentioned. To contextualize the topic, a study of the history of the music video will be developed as well as his vinculation with the architecture along his technological development. Also, there will be stabilized the bases and origins of the music urban genre and his close social and political relationship to reach the understanding of the different studied cases. Furthermore, there will be tried to generate, based on theorical bases sufficiently strong, the relationship between urban space and architecture and this new wave of artista who configure the result of an economic, politic and social fabric of the post-industrial capitalist world., Grado en Fundamentos de Arquitectura y Urbanismo

A catalyst 0.1VP(0.2)O-Cr(0.01)-PEG(1 × 10−4)/Ti for low-temperature SCR de-NOx was developed and the effects of SO2 and water vapor on its catalytic activity were investigated. Cr doping increases the molar ratio of V5+ to V4+ on the VPO catalyst, which promote oxidation of NO to NO2 and catalytic activity of the VPO catalyst. An appropriate amount of redox-coupled V5+/V4+ also promotes catalytic activity of the VPO catalyst. The denitration efficiency over 0.1VP(0.2)O-Cr(0.01)-PEG(1 × 10−4)/Ti was above 98% at 150–350°C. Cr doping also promotes the generation of Lewis acid around V5+ center and Brønsted acid (P-OH) on the VPO catalysts. The strong surface acidity of 0.1VP(0.2)O-Cr(0.01)-PEG(1 × 10−4)/Ti could restrain the adsorption of and oxidation of SO2. Characterization (FT-IR, TG) results indicate that nearly no sulfate was deposited on the surface of 0.1VP(0.2)O-Cr(0.01)-PEG(1 × 10−4)/Ti after activity test. The competitive adsorption of water molecules and nitric oxide on the catalyst surface decreases the catalytic activity of the VPO catalyst. The addition of Cr and PEG could increase the surface area and the exposure of active site of VPO catalyst, which also increase the unoccupied active sites of VPO catalysts in the presence of water vapor. The catalyst 0.1VP(0.2)O-Cr(0.01)-PEG(1 × 10−4)/Ti for low-temperature SCR de-NOx shows high catalytic activity and exhibits high resistance to SO2 and water vapor.

Two VPO materials with fibrillar morphology have been prepared by the aid of electrospinning technique. One is a VPO carbon-supported material (VCF200) with fibrous morphology and very high surface area that is stable under oxidizing conditions up to 350C. The other material is a bulk mixed VPO oxide (VPO500) with fibrous structure obtained after optimizing the calcination of the carbon support in VCF200. Despite it is a bulk oxide material, this material exhibits a high surface area (> 60 m2/g). The redox behavior of both samples was monitored by in situ Raman spectroscopy under oxidation/reduction cycles. For the dehydrated supported sample (VCF200), the pyrophosphate phase (VO)2P2O7 (Raman ~930 cm-1) is detected, which has been described as the active phase (see Figure (a) below). This phase is quite stable since it does not disappear upon subsequent oxidation/reduction cycles. Under reduction conditions at 125C, in consecutive cycles, additional Raman bands appear at ~1090 cm-1 that are characteristic of the αII-VOPO4 phase. On the other hand, the bulk phases show a reversible behavior under redox cycles (Figure (b)). Under reducing conditions, a Raman band appears at ~980 cm-1 (β-VPO phase), whereas under oxidation conditions some segregation to VOx oxides occurs. Nevertheless, this segregation is reversible and the β-VPO phase forms again under reducing conditions. Thus, these results demonstrate that the active VPO phases of these fibrous catalysts are quite stable, and that their structure is reversible under several redox cycles, which make them suitable as oxidation catalysts. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

Resumen comunicación a congreso internacional Vanadium phosphates is one of the most studied heterogeneous catalytic systems due to its properties to activate alkanes. In fact, they are used commercially for the oxidation of n-butane to maleic anhydride and experimental studies have shown that vanadium phosphates are also effective catalysts for propane and pentane partial oxidation. The most active phase of VPO catalysts is made up of a well-crystallized (VO)2P2O7, which is considered to possess unique structural and surface features to allow the activation of alkanes. This phase is generally generated by calcination of the precursor VOHPO4·0.5H2O. A new strategy to obtain this precursor has been analyzed in this study. The proposed methodology is simple and low cost and implies the use of a carbon material as a template to obtain the mixed oxide with a developed porous structure. Several VPO catalysts were prepared by using different activated carbons, which were obtained from lignocellulosic waste, as template. The carbonaceous materials were obtained by chemical activation with phosphoric acid of olive stones and by liquid phase impregnation of zeolite templates with lignin solution. Both porous carbons were impregnated with a solution containing the dissolved vanadium phosphate precursor. This solution was prepared by mixing water with ammonium metavanadate, phosphoric acid and oxalic acid in the precise amounts to obtain a V/P atomic ratio of 1. Finally, in order to remove the carbonaceous matrix and to obtain the active phase (VO)2P2O7, the impregnated samples were calcined in air at 500 ºC for 6 h. The presence of the desired active phase (VO)2P2O7 was confirmed by using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and X-ray diffraction (XRD). The porous structure was characterized by N2 adsorption-desorption at -196 ºC. Catalytic tests were performed in a fixed bed microreactor under a gas flow mixture (W/F = 0,075 g·s·mL-1) containing propane, oxygen and helium (45.7/11.4/42.9 vol. %). The reaction was studied at different temperatures from 500 to 575 ºC. The use of a carbon as a template results in VPO catalysts with relatively high development of the porous structure (apparent surface area of 40 m2/g), compared to those reported in the literature. These catalysts present propane conversions up to 22 % with selectivities to propylene as high as 60 %. It is noteworthy that selectivities to ethylene about 25% were also observed, which is a highly valued product in the chemical industry. These results are comparable to those reported in the literature for supported vanadium oxides at higher space times. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

En las últimas décadas, el estudio y desarrollo de carbones activos como catalizadores o soportes catalíticos se ha incrementado enormemente debido a las ventajas derivadas de su elevada capacidad adsorbente, inercia y estabilidad química, una química superficial versátil y elevada resistencia mecánica. Además, su preparación a partir de residuos biomásicos supone un beneficio no sólo económico, sino también medioambiental, que puede resultar clave en el contexto energético e industrial actual. El objetivo de la tesis doctoral es la preparación y caracterización de catalizadores carbonosos obtenidos mediante activación química de residuos lignocelulósicos. Se ha activado un residuo biomásico como es el hueso de aceituna mediante impregnación con H3PO4 a diferentes relaciones de impregnación y temperaturas de activación. A pesar del proceso de lavado, una cantidad significativa de fósforo, permanece unida de forma estable a la superficie de los carbones obtenidos proporcionando una elevada concentración de grupos superficiales ácidos y una alta resistencia a la oxidación, lo que les confiere una particular química superficial. Este hecho, unido al notable desarrollo de la estructura porosa, con una contribución significativa de la microporosidad ancha y de la mesoporosidad, hace que estos carbones activos sean muy interesantes como sistemas catalíticos. En la presente tesis se ha estudiado la descomposición de alcoholes sobre los carbones activos ácidos. Los resultados mostraron que los carbones preparados son activos para la conversión catalítica de metanol y etanol, en aire, obteniéndose principalmente productos de deshidratación. Además, se han analizado las cinéticas de los resultados experimentales obtenidos, se han planteado modelos mecanísticos basados, inicialmente, en los ya propuestos en la bibliografía y se han formulado nuevos modelos, se ha estudiado la validez de éstos en base a la bondad de los ajustes y, finalmente, se obtuvieron las constantes cinéticas y termodinámicas para cada uno de los procesos. Por otro lado, estos carbones activados con ácido fosfórico se han usado como soporte de especies de óxido de vanadio. De esta manera se ha obtenido un catalizador VPO soportado en carbón activo y se ha estudiado su uso en las reacciones de oxidación parcial de propileno y la oxidación deshidrogenativa de propano (ODH). Además, se obtuvieron catalizadores másicos de VPO con morfología esférica y estructuras huecas tras una etapa de calcinación. Una de las principales características de estos sistemas catalíticos es la elevada área superficial, tanto de los óxidos soportados como másicos lo que los hace muy interesantes para aplicaciones catalíticas. La incorporación de vanadio al soporte de carbón activo disminuye la temperatura de oxidación de éste, pero, en cualquier caso, los catalizadores son estables en las condiciones de operación. Los datos de actividad fueron muy interesantes en el caso de la reacción de ODH de propano, que resultaron muy próximos a los valores más altos reportados para esta reacción, lo cual hace a estos catalizadores prometedores para su uso en reacciones de oxidación parcial de hidrocarburos, a la vez que abre una nueva posibilidad a los carbones activos como sistemas catalíticos en procesos de interés tecnológico., 2018-05-20

The present work addresses the issue of the promoter effect produced by group VIB elements added to the basic VPO formulation using different methods and loads in order to obtain information linking the catalytic behavior of the solids with their physicochemical properties. The unpromoted VPO precursor (VOHPO4·1/2H2O) was prepared from V 2O5 reduced with an alcoholic mixture and 100% H 3PO4. Cr, Mo or W were either impregnated on the VPO precursor or co-precipitated during the precursor synthesis. The precursors containing varying loads of the promoter were activated following a standard procedure in the same flow micro-reactor where the catalytic performance was evaluated. The precursors and the catalysts were characterized by X-ray diffraction (XRD) and laser Raman spectroscopy (LRS). Acetonitrile was used as a probe molecule to test the strength of the Lewis acid sites monitored by FTIR. The amount of chemisorbed acetonitrile was measured in a standard high vacuum system. The addition of the promoters invariably increased the catalytic activity but in every case there was an optimum load to achieve the best selectivity. The origin of this maximum could be ascribed to the right balance between the presence of very strong Lewis acid sites and the development of V5+ isolated sites in the matrix of the vanadyl pyrophosphate, by far the major crystalline phase present in the catalyst. The three group VIB promoters affect the balance between acid and redox properties but increase the overall activity in all cases. Fil: Pierini, Beatriz T.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Lombardo, Eduardo Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina

Preparation of 2-Chlorobenzonitrile, and benzonitrile are reported here from the corresponding 2-Chlorobenzaldehyde and benzaldehyde by the reaction of ammonium hydroxide/VPO titania, VPO bulk (ammonium metavanadate) CuCr catalyst/air system in methanol. All these catalysts showed better conversions with reasonable selectivity to aromatic. The results prove that BET surface area results show VPO is present on the catalysts surface which has high surface area, attributed to increase in activity of the catalysts.

International audience; The magnetic properties of [(VO)3(μ-PO4)2(2,2′-bpy)(μ-OH2)]1/3H2O (1) and (VO)2H4P2O9 (2), a tubular and a layered vanadium(IV) phosphates containing triply oxido bridged VIV dimers, are analyzed considering the Bleaney-Bowers S = 1/2 dimer model. In compound 1 the presence of an additional VIV connected with the VIV dimers through μ1,2-PO43− bridges is described with a Curie-Weiss type correction. This model reproduces the magnetic properties of compound 1 with g = 1.956, Jdim = −102.1 cm−1, θ = −0.4 cm−1 and Nα = 278 × 10−6 emu mol−1. In compound 2, the presence of a small percentage of paramagnetic impurity has to be considered to account for the divergence of χm at low temperatures. This simple model reproduces the magnetic data of compound 2 with g = 1.99, J = −62.4 cm−1 and a 1.2% of monomeric impurity. The moderate antiferromagnetic coupling found in the triply oxido bridges VIV dimers is justified from the structural parameters of the bridge. These studies confirm that the coupling through -O-P-O- bridges is antiferromagnetic and relatively weak, as well as previous magneto-structural correlations in this kind of oxido bridges. DFT calculations on a dinuclear fragment model for the two systems gave the following values of Jcalc = −72.4 cm−1 for 1 and Jcalc = −5.2 cm−1 for 2. These values reproduce the antiferromagnetic nature of the superexchange interactions between the VIV centers.

Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica No presente estudo prepararam-se catalisadores do tipo VPO (Vanadium-Phosphorous-Oxygen) impregnando metavanadato de amónio num carvão activado quimicamente com ácido fosfórico. Actualmente estes catalisadores são usados industrialmente na conversão de butano a ácido maleico. Todavia, o interesse, no ponto de vista reaccional, foi o estudo da actividade catalítica de VPO’s na desidrogenação oxidativa do propano (ODH), na medida em que se trata duma reacção de baixo rendimento, e, portanto, é da maior importância optimizar as condições experimentais de modo a poder ser realizada industrialmente. O objectivo desta investigação foi a utilização de esferas de carvão activado como template, permitindo obter catalisadores de forma esférica e oca, utilizando um método de síntese economicamente viável. O catalisador de VPO apresenta forma esférica e oca, devido à eliminação do carvão activado da matriz porosa, utilizando um tratamento térmico. O carvão activado foi preparado de modo a obterem-se partículas esféricas que servissem de template. Optou-se pela eliminação do template, porque as temperaturas da reacção ODH são superiores à temperatura de decomposição térmica do carvão. As amostras foram caracterizadas texturalmente por adsorção de N2 e CO2 a 77K e 273K, respectivamente. Os catalisadores foram ainda caracterizados por Difracção de Raios-X (XRD) e Espectroscopia Fotoelectrónica de Raios-X (XPS). Como análises complementares de caracterização, efectuaram-se ensaios de Termogravimetria (TG) e Microscopia Electrónica de Varrimento (SEM) para avaliar a resistência térmica e obter informação sobre a morfologia macroscópica dos VPO’s. Os resultados do estudo da actividade catalítica na recção de desidrogenação oxidativa do propano mostram, no geral, conversões baixas (inferiores a 10%), contudo as selectividades de propileno são bastante elevadas, atingindo um valor máximo de 87.5%.

International audience; The structural properties and oxidation state of vanadium in alumina-supported vanadium-phosphorous oxides at nearly monolayer coverage influence its catalytic performances. The population distribution V-V=O and V-IV=O species in the amorphous VPO phase strongly depends on the sample history. By using alumina-supported VPO instead of conventional bulk catalysts, we facilitate enhanced discrimination between active phase and bulk phase signals in the vanadium-phosphorous oxygen system. This brings light on the speciation of VPO catalysts in general. Our observations were achieved by using mainly in situ EPR & operando Raman-GC spectroscopic techniques at relevant temperatures and gas conditions, showing that the ((VO)-O-iv)(2)P2O7 phase is formed during propane ammoxidation at 753 K. Such transformation is less intense in inert atmosphere at 753 K. Ammonia adsorption on the VPO catalyst surface leads to the formation of VO2+ sites, probably bearing Bronsted and/or Lewis acidity. Propane ammoxidation appears to promote the formation of mixed valence compounds. (c) 2012 Elsevier B.V. All rights reserved.

El estudio de las resinas y los asfaltenos, las fracciones más pesadas del petróleo, se ha convertido en un área de interés, debido a la abundancia de crudos pesados en Colombia y en América Latina. En este trabajo se estudió la composición quómica de las fracciones pesadas del crudo Castilla, se evaluaron algunos de sus parámetros moleculares y se evidenció la interacción entre la resina extraóda del crudo con los asfaltenos del crudo original. Para este propósito, se realizó, la precipitación, a nivel de planta piloto, del agregado resina-asfalteno (R-A), por adición y mezcla a condiciones controladas, de un solvente parafónico, proveniente de la refineróa de Apiay, denominado Apiasol. Mediante extracción Soxhlet con el mismo solvente, se separó la resina I del agregado R-A. La resina II, definida como la fracción soluble que hace parte de los maltenos, se separó del crudo desasfaltado, por cromatografóa de columna abierta, utilizando alúmina como soporte según el método Saturado, Aromáticos, Resinas (SAR). Las fracciones de resinas y los asfaltenos obtenidos, se caracterizaron por: Resonancia Nuclear Magnética (RNM), FT-IR, Difracción de Rayos X (DRX), análisis elemental (C, H, N, S), contenido de metales (Ni y V), distribución del peso molecular por Cromatrografóa de Permeación por Gel (GPC), y peso molecular promedio por Osmometróa de Presión Vapor (VPO). Los resultados obtenidos, evidencian que la resina I que forma parte del agregado es de menor peso molecular promedio que la resina II presente en la fracción de maltenos. Adicionalmente, se encuentran algunos cambios en el análisis elemental entre las resinas. Por otro lado y teniendo en cuenta las teoróas existentes respecto a las interacciones moleculares entre estas fracciones, se encontró que las resinas I separadas del agregado R-A, al adicionarse al crudo estabilizan sus asfaltenos. Esta evaluación se realizó, analizando el punto de floculación del crudo y sus mezclas con 1,9% y 3,8% de resina I, cuando son tituladas con un agente precipitante, en una celda NIR que trabaja a alta presión y temperatura. The study of resins and asphaltenes, the heaviest fractions of oil, has become an area of interest due to the abundance of heavy crude oils in Colombia and Latin America. We studied the chemical composition of the heavy fractions of Castilla crude oil, evaluated some of its molecular parameters and found evidence of the interaction between the resin extracted from the crude with the asphaltenes of the original crude. With this objective, we carried out at the pilot plant level precipitation of the resin-asphaltene (R-A) aggregate by adding and mixing under controlled conditions, a paraffin solvent, from the Apiay refinery, called Apiasol. By extracting Soxhlet with the same solvent, resin I of aggregate R-A was separated. Resin II defined as the soluble fraction that is part of the maltenes, was separated from the deasphalted crude by open column chromatography, using alumina as support, according to the SAR method (Saturated, Aromatcis, Resins). The fractions of resins and the asphaltenes obtained, were characterized by: Nuclear Magnetic Resonance (NMR), FT-IR, DRX, elementary analysis (C, H, N, S), metal content (Ni and V), distribution of molecular weight by GPC, and average molecular weight by VPO. The results obtained show evidence that resin I which is part of the aggregate has less average molecular weight than resin II which is present in the fraction of maltenes. In addition, some changes were found in the elementary analysis of among the resins. On the one hand, and taking into account the existing theories of molecular interactions among these fractions, it was found that the resins I separated from the R-A aggregate, when added to the crude, they stabilize their asphaltenes. This evaluation was carried out by analyzing the flocculation point of the crude and its mixtures with 1,9% and 3,8% of resin I, when they are titrated with a pricipitating agent in an NIR cell that works with high pressure and temperature.

Both thermodynamics and kinetics studies were systematically investigated on the liquid-liquid extraction of the nickel(II) by 2-ethylhexanal oxime (EHO) and its mixture with di-(2-ethylhexyl) phosphoric acid (D2EHPA) in dodecane.Various aggregations of the EHO and D2EHPA were characterized by vapour pressure osmometry technique VPO. While EHO and D2EHPA multimers were shown to be monomers (namely HOx and HA), dimers and trimers, no mixed complex between EHO and D2EHPA is evidenced.The study of the extraction of the nickel by the oxime was carried out in various aqueous media. If kinetics was relatively slow, only chloride favoured the extraction from acidic media. The organic extracted complexes were identified by means of the slope method. In the presence of NH4NO3 or without any salt, the complexes were Ni(Ox)2(HOx)n. In chloride medium, the organic complex were NiCl2(HOx)n for quite acidic media (pHThe kinetic study, conducted in a highly stirred homothetic cell of Rushton type, showed that the extraction process undergone interfacial limitations. For the chloride media, the limiting step is the solvation reaction of the neutral complex NiCl2(H2O) for pHThe addition of D2EHPA co-extractant led to a significant kinetics enhancement. The organic extracted complex was identified as NiA2(Hox) through slope method and iso-molecular study. The limiting step was an interfacial reaction of cationic exchange type between the adsorbed Ni(A)(H2O)5+ and the HA monomer. For comparison, kinetic study was equally achieved in a constant interfacial area cell of Armollex type. Chemical results were exhaustively confirmed and the interfacial specific area value deduced for the Rushton cell.; Une étude thermodynamique et cinétique systématique a été entreprise sur l'extraction liquide-liquide du nickel(II) par la 2-ethylhexanal oxime (EHO) seule ou en mélange avec l'acide di-(2-éthylhexyl) phosphorique (D2EHPA) en solution dans le dodécane.La caractérisation des différentes agrégations de la EHO et du D2EHPA par osmométrie VPO a montré l'existence de monomères (notés respectivement HOx et HA), de dimères et de trimères ainsi que l'absence d'espèce mixte EHO-D2EHPA.L'étude de l'extraction du nickel par l'oxime seule à partir de différents milieux aqueux a montré que la cinétique est relativement lente et que seuls les chlorure permettent l'extraction en milieu acide. Les différents types de complexes organiques extraits ont été mis en évidence. En l'absence de sel ou avec NH4NO3, les complexes extraits sont respectivement Ni(Ox)2(HOx)n où n vaut 3 ou 4 pour de plus fortes concentrations en oxime. En présence de chlorure, les complexes extraits sont NiCl2(HOx)n en milieu acide (pHL'étude cinétique, conduite dans une cellule agitée de type Rushton, a montré que le processus est contrôlé par une étape interfaciale. Elle correspond à la réaction de solvatation du complexe neutre NiCl2(H2O), (pH4), par une molécule d'oxime dans le cas des chlorures ; pour les autres électrolytes, il s'agit de l'échange cationique entre Ni(Ox)(H2O)5+ et HOx.L'ajout d'un co-extractant (D2EHPA) provoque une accélération cinétique significative. Le complexe extrait est NiA2(HOx), confirmé par ailleurs par une étude iso-moléculaire. L'étape limitante est une réaction interfaciale d'échange cationique entre NiA(H2O)5+ adsorbé et HA. Pour comparaison, l'étude cinétique a été également conduite dans une cellule à aire interfaciale constante de type Armollex et a permis une estimation de l'aire interfaciale spécifique développée dans la cellule agitée.

Both thermodynamics and kinetics studies were systematically investigated on the liquid-liquid extraction of the nickel(II) by 2-ethylhexanal oxime (EHO) and its mixture with di-(2-ethylhexyl) phosphoric acid (D2EHPA) in dodecane.Various aggregations of the EHO and D2EHPA were characterized by vapour pressure osmometry technique VPO. While EHO and D2EHPA multimers were shown to be monomers (namely HOx and HA), dimers and trimers, no mixed complex between EHO and D2EHPA is evidenced.The study of the extraction of the nickel by the oxime was carried out in various aqueous media. If kinetics was relatively slow, only chloride favoured the extraction from acidic media. The organic extracted complexes were identified by means of the slope method. In the presence of NH4NO3 or without any salt, the complexes were Ni(Ox)2(HOx)n. In chloride medium, the organic complex were NiCl2(HOx)n for quite acidic media (pHThe kinetic study, conducted in a highly stirred homothetic cell of Rushton type, showed that the extraction process undergone interfacial limitations. For the chloride media, the limiting step is the solvation reaction of the neutral complex NiCl2(H2O) for pHThe addition of D2EHPA co-extractant led to a significant kinetics enhancement. The organic extracted complex was identified as NiA2(Hox) through slope method and iso-molecular study. The limiting step was an interfacial reaction of cationic exchange type between the adsorbed Ni(A)(H2O)5+ and the HA monomer. For comparison, kinetic study was equally achieved in a constant interfacial area cell of Armollex type. Chemical results were exhaustively confirmed and the interfacial specific area value deduced for the Rushton cell., Une étude thermodynamique et cinétique systématique a été entreprise sur l'extraction liquide-liquide du nickel(II) par la 2-ethylhexanal oxime (EHO) seule ou en mélange avec l'acide di-(2-éthylhexyl) phosphorique (D2EHPA) en solution dans le dodécane.La caractérisation des différentes agrégations de la EHO et du D2EHPA par osmométrie VPO a montré l'existence de monomères (notés respectivement HOx et HA), de dimères et de trimères ainsi que l'absence d'espèce mixte EHO-D2EHPA.L'étude de l'extraction du nickel par l'oxime seule à partir de différents milieux aqueux a montré que la cinétique est relativement lente et que seuls les chlorure permettent l'extraction en milieu acide. Les différents types de complexes organiques extraits ont été mis en évidence. En l'absence de sel ou avec NH4NO3, les complexes extraits sont respectivement Ni(Ox)2(HOx)n où n vaut 3 ou 4 pour de plus fortes concentrations en oxime. En présence de chlorure, les complexes extraits sont NiCl2(HOx)n en milieu acide (pHL'étude cinétique, conduite dans une cellule agitée de type Rushton, a montré que le processus est contrôlé par une étape interfaciale. Elle correspond à la réaction de solvatation du complexe neutre NiCl2(H2O), (pH4), par une molécule d'oxime dans le cas des chlorures ; pour les autres électrolytes, il s'agit de l'échange cationique entre Ni(Ox)(H2O)5+ et HOx.L'ajout d'un co-extractant (D2EHPA) provoque une accélération cinétique significative. Le complexe extrait est NiA2(HOx), confirmé par ailleurs par une étude iso-moléculaire. L'étape limitante est une réaction interfaciale d'échange cationique entre NiA(H2O)5+ adsorbé et HA. Pour comparaison, l'étude cinétique a été également conduite dans une cellule à aire interfaciale constante de type Armollex et a permis une estimation de l'aire interfaciale spécifique développée dans la cellule agitée.