Abstract This thesis examines temporal and spatial variations in the status of different rivers and streams of western Finland in terms of acidity and sources of acid load derived from the catchment area. It also examines the monitoring of acid runoff water derived from maintenance drainage in peatland forestry and suggests potential mitigation methods. A total of 17 river basins of different sizes in western Finland were selected for study, including rivers affected by both drainage of agricultural AS soils and forested peatlands. Old data from 1911–1931 were available, but most data were from the 1960s onwards and were taken from the HERTTA database. During 2009–2011, pH and conductivity measurements and water sampling were conducted. Biological monitoring for ecological classification was conducted in the Sanginjoki river system during 2008 and 2009. Three peatland forestry sites were selected to study acid leaching via pH and EC measurements and water sampling. Fluctuations in groundwater level in different drainage conditions were simulated and acid leaching was investigated in laboratory experiments in order to replicate a situation where the groundwater level drops and allows oxidation of sulphidic materials. It was found that river pH decreased and metal concentrations increased with runoff. The highest acidity observed coincided with periods of intense drainage in the 1970s and after dry summers in the past decade. Together with pH, electric conductivity and sulphate in river water were identified as suitable indicators of AS soils in a catchment, because they directly respond to acid leaching derived from AS soils. Acidity derived from organic acids was clearly observed in catchments dominated by forested peatlands and wetlands. Temporal and spatial variations in ecological status were observed, but monitoring at whole-catchment scale and during consecutive years is needed to increase the reliability of the results. Simulations on the potential effects of maintenance drainage in peatland forestry on runoff water quality showed a clear risk of oxidation of sulphidic materials during dry summers. This can be prevented mainly by avoiding too deep drainage. Knowledge of the hydrochemical impacts of acidic load derived from AS soils and drained peatlands is necessary for land use planning and sustainable water management of river basins affected by these soils. / Tiivistelmä Tutkimuksessa tarkastellaan Suomen länsirannikon happamuudesta kärsivien jokivesistöjen tilan ajallista ja paikallista vaihtelua. Tutkimuskohteena on sekä happamien sulfaattimaiden että ojitettujen turvemaiden jokivesistöjä. Tutkimuksessa tarkastellaan myös sulfidipitoisilta metsäojitetuilta turvemailta valuvaa happamuutta sekä ehdotetaan tällaisille kohteille soveltuvia keinoja huuhtouman ehkäisemiseksi. Tutkimukseen valittiin 17 erikokoista jokivesistöä, joiden valuma-alueella on sekä happamia sulfaattimaita että metsäojitettuja turvemaita. Varhaisin väitöskirjaan sisällytetty aineisto on vuosilta 1911–1931. HERTTA-tietokannasta poimittiin aineistoa happamuusmuuttujista 1960-luvulta alkaen. Vuosina 2009–2011 suoritettiin pH- ja sähkönjohtavuusmittauksia sekä otettiin vesinäytteitä Siika- ja Pyhäjoen valuma-alueen joista sekä näiden välissä sijaitsevien pienempien valuma-alueiden joista. Ekologisen tilan selvittämiseksi otettiin biologiset näytteet Sanginjoen valuma-alueen joista ja puroista vuosien 2008 ja 2009 aikana. Kunnostusojituskohteilla seurattiin pH:n ja sähkönjohtavuuden muutoksia kokoojaojissa sekä otettiin vesinäytteitä. Pohjaveden pinnan vaihtelua selvitettiin sekä kenttämittauksilla että mallinnuksen avulla. Laboratoriokokeen avulla selvitettiin sulfidien hapettumista. Metallipitoisuudet nousivat ja pH laski valumien kasvaessa. 1970-luvulla toteutetut salaojitukset heijastuivat jokien happamuuden kasvuna. Myös viime vuosikymmenen kuivat kesät näkyivät veden happamuuden lisääntymisenä syksyn ylivirtaamatilanteissa. Veden pH, sähkönjohtavuus sekä sulfaatti ilmensivät happamien sulfaattimaiden esiintymistä valuma-alueella. Orgaanisista hapoista peräisin olevaa happamuutta havaittiin valuma-alueilla, joilla on runsaasti ojitettuja turvemaita. Ekologisen tilan ajallisen ja paikallisen vaihtelun vuoksi seurantaa tulisi toteuttaa peräkkäisinä vuosina sisällyttäen tarkasteluun valuma-alueen eri jokia ja puroja. Kunnostusojitukset voivat aiheuttaa happamuutta, jos ojitus ulottuu sulfidikerrokseen. Riski on olemassa poikkeuksellisen kuivina kesinä. Sulfidien hapettumista voidaan ehkäistä välttämällä liian syvien ojien kaivamista. Maatalouskäytössä olevilta happamilta sulfaattimailta ja ojitetuilta turvemailta peräisin olevan huuhtouman vaikutukset tulee tuntea, jotta valuma-alueiden maankäyttöä ja vesiensuojelua voidaan toteuttaa tehokkaasti.

Une nouvelle famille de catalyseurs a été développée pour la déshydratation des alcools en C2-C4. Ces catalyseurs qui correspondent à des phosphates de terres rares, sont plus actifs et au moins aussi sélectifs que les catalyseurs traditionnels de déshydratation et ils ne montrent que des désactivations limitées en fonction du temps par dépôt de coke à leur surface. Plusieurs méthodes de préparation de ces catalyseurs ont été développées et les catalyseurs ont été caractérisés par DRX, spectroscopie IR, Raman, MET, EDX, XPS. L’acido-basicité des catalyseurs a été étudiée par TPD de NH3 et CO2 et adsorption de pyridine et de lutidine suivie par IR. Les études catalytiques ont permis de montrer que le mécanisme principal de déshydratation est de type E1 et que les principaux sites catalytiques sont des sites acides de Bronsted ou de Lewis. Les sites acides de Bronsted correspondent à des d’espèces (H2PO4)2- dont la présence est liée à un excès de phosphore en surface, les sites acides de Lewis correspondent aux ions terre rare. L’implication des deux types de sites a été étudiée en fonction de plusieurs paramètres. Les performances des catalyseurs ont été attribuées à une quantité importante de sites acides moyennement forts et à une très faible quantité de sites basiques faibles. Dans la déshydratation du 1-butanol, il apparaît clairement que les sites les plus actifs et les plus sélectifs en 2-butene sont des sites acides de Bronsted. Sur un plan plus appliqué la thèse a permis de mettre au point de nouveaux procédés de préparation de propène soit direct soit passant par une étape de métathèse (éthylène + 2-butène), de 1 et 2- butène et de butadiène (déshydratation du 3-butène-1-ol et du 2, 3-butanediol) / A new family of catalysts has been developed for the dehydration of C2-C5 alcohols. These performing catalysts, which correspond to lanthanides phosphates, are more active and at least as selective when compared to traditional efficient dehydration and show very limited deactivation under reaction flow due to coke deposition. Different methods of preparation of the catalysts have been developed and the catalysts have been characterized by various techniques like XRD, Raman spectroscopy, TEM with EDX analyses and XPS. The acid base properties of the solids have been studied by NH3 and CO2 TPD and by adsorption of lutidine and pyridine followed by IR. The catalytic studies allow showing that the main reaction mechanism on the solids was E1-type and the active sites are both Bronsted and Lewis sites. The Bronsted acid sites correspond to (H2PO4)2- species which presence is related to an excess of P at the surface and the Lewis acid sites correspond to the rare earth cations. The implication of both types of sites as a function of different parameters has been studied. The high efficiency has been attributed to a high amount of acid sites with a moderated acid strength and to a very low amount of basic sites with weak strength. In the dehydration of 1-butanol it appears clearly that the more active and selective sites are Brosnted acid sites. On an industrial point of view the, the thesis work allowed to design new processes of production of propene either direct or through a metathesis reaction (ethylene+ 2-butene), of 1 and 2-butene and of butadiene (dehydration of 3-butene-1-ol and 2, 3-butanediol

Abstract The aim of the thesis is to expand the knowledge of the catalytic properties of platinum-loaded zeolite catalysts in the reduction of NOx by hydrocarbons. The work is divided into three parts. First the recent literature of zeolite catalysts has been introduced, secondly the adsorption capacity, activity, and acidity of the catalysts have been studied by TPD and IR techniques, and thirdly the derived reaction mechanisms based on the obtained data are presented. Parent and 1 wt-% Pt-loaded ZSM-5, Beta, Y, and Ferrierite zeolite catalysts have been studied in the C3H6-assisted reduction of NO. The Pd/Al2O3-based catalyst was used as a reference material for the reaction mechanistic studies. Several experimental techniques (in situ DRIFT, activity measurements, CO chemisorption, N2 physisorption, TPD, and TEM) have been used for the characterisation of the catalysts properties. The IR technique was used as the main technique for the determination of activities, surface species, and the acidic properties of the zeolite-based catalysts. The activity studies carried out by the gaseous FTIR technique provide information on the desired reaction products as well as the undesired by-products. The detection and identification of the surface species as well as the reaction intermediates formed were done by the DRIFT method. The activity experiments indicate the effectiveness of the Pt-loaded zeolite catalysts. The reduction of NO was found to decrease in the order: Pt/Beta > Pt/Y > Pt/Ferrierite > Pt/ZSM-5 in the conditions with excess O2. Platinum can be concluded to have an effect on O2 and NO dissociation. Oxidation reactions of NO to NO2 and propene to CO2 were observed to be more intense over the platinum-loaded zeolites than over the parent zeolites. In this work the reaction mechanisms for the C3H6-SCR of NO were derived over the Pt-loaded zeolite as well as the Pd/alumina catalysts based on the data obtained by DRIFT and activity experiments. The kinetics for the NO reduction by CO over Pd/Al2O3 was also derived. With the methods employed, the mechanistic steps over the Pt-loaded zeolites and Pd/Al2O3-based catalysts could be derived quite precisely and easily for C3H6-SCR of NO. Reaction routes were determined to go via different formations of intermediates over the two catalysts, i.e. via organonitrogen and isocyanate routes, respectively. The IR techniques were discovered to be effective tools in applied engineering studies.

Made available in DSpace on 2016-01-26T18:56:33Z (GMT). No. of bitstreams: 1 Dissertacao.pdf: 190502 bytes, checksum: 5752f80c9f704bcfdb2fab5cb3f0b55c (MD5) Previous issue date: 2008-08-27 / This work evaluated the behavior of phosphorus sources: Arad phosphate, Alvorada phosphorite and Triple Superphosphate in two soils a sandy and a clay 70% basis saturation in the natural acidity condition. The experimental outlining was totally randomized in a factorial scheme (2x2x3x4), being: two soils; three phosphate fertilizer sources; and four doses (0, 100, 200 and 400 Kg ha-1), with four repetitions. The results were submitted to the analysis variation, being taken the retrogression one, adjusting the equations and using as a criterion to the statistical pattern choice the significative F tests from 1 to 5%, and magnitude of determination coefficients. The phosphate fertilizers raised the calcium and the phosphorus proportions in the sand and in the sand-clay soils, both in presence and in absence of liming. The arad, applied in high doses in the acid soils, changed the pH of the sandy and the clay soils were noticed in the treatments that received an Alvorada Phosphorite application, and the highest proportions of the Triple Superphosphate and the Arad showed intermmediate proportions of available phosphorus. / Este trabalho avaliou o comportamento das fontes de fósforo: Arad, Fosforita Alvorada e Superfosfato Triplo em dois solos. - um arenoso e outro argiloso. -, na condição de acidez natural e, após a correção, atingir saturação por bases a 70%. O delineamento experimental utilizado foi inteiramente casualizado, com esquema fatorial (2x2x3x4), sendo: dois solos; três fontes de fertilizantes fosfatados e quatro doses (0, 100, 200 e 400 Kg há -1), com quatro repetições. Os resultados foram submetidos à análise de variância, sendo adotada a análise de regressão, ajustando-se as equações, e tendo-se como critério para escolha do modelo estatístico os testes F significativo a 1 a 5%, e (magnitude dos coeficientes de determinação). Os fertilizantes fosfatados elevaram os teores de cálcio e fósforo nos solos arenoso e argiloso na presença e ausência de calagem. O Arad, aplicado em doses elevadas nos solos ácidos, alterou o pH dos solos arenoso e argiloso. Os menores teores de fósforo disponível no solo foram observados nos tratamentos que receberam a aplicação de Fosforita Alvorada, e os maiores teores para o Superfosfato Triplo e o Arad apresentaram teores intermediários de fósforo disponível.

Made available in DSpace on 2016-07-18T17:51:15Z (GMT). No. of bitstreams: 1 Dissertacao.pdf: 190502 bytes, checksum: 5752f80c9f704bcfdb2fab5cb3f0b55c (MD5) Previous issue date: 2008-08-27 / This work evaluated the behavior of phosphorus sources: Arad phosphate, Alvorada phosphorite and Triple Superphosphate in two soils a sandy and a clay 70% basis saturation in the natural acidity condition. The experimental outlining was totally randomized in a factorial scheme (2x2x3x4), being: two soils; three phosphate fertilizer sources; and four doses (0, 100, 200 and 400 Kg ha-1), with four repetitions. The results were submitted to the analysis variation, being taken the retrogression one, adjusting the equations and using as a criterion to the statistical pattern choice the significative F tests from 1 to 5%, and magnitude of determination coefficients. The phosphate fertilizers raised the calcium and the phosphorus proportions in the sand and in the sand-clay soils, both in presence and in absence of liming. The arad, applied in high doses in the acid soils, changed the pH of the sandy and the clay soils were noticed in the treatments that received an Alvorada Phosphorite application, and the highest proportions of the Triple Superphosphate and the Arad showed intermmediate proportions of available phosphorus. / Este trabalho avaliou o comportamento das fontes de fósforo: Arad, Fosforita Alvorada e Superfosfato Triplo em dois solos. - um arenoso e outro argiloso. -, na condição de acidez natural e, após a correção, atingir saturação por bases a 70%. O delineamento experimental utilizado foi inteiramente casualizado, com esquema fatorial (2x2x3x4), sendo: dois solos; três fontes de fertilizantes fosfatados e quatro doses (0, 100, 200 e 400 Kg há -1), com quatro repetições. Os resultados foram submetidos à análise de variância, sendo adotada a análise de regressão, ajustando-se as equações, e tendo-se como critério para escolha do modelo estatístico os testes F significativo a 1 a 5%, e (magnitude dos coeficientes de determinação). Os fertilizantes fosfatados elevaram os teores de cálcio e fósforo nos solos arenoso e argiloso na presença e ausência de calagem. O Arad, aplicado em doses elevadas nos solos ácidos, alterou o pH dos solos arenoso e argiloso. Os menores teores de fósforo disponível no solo foram observados nos tratamentos que receberam a aplicação de Fosforita Alvorada, e os maiores teores para o Superfosfato Triplo e o Arad apresentaram teores intermediários de fósforo disponível.

Many proteins are unstable in solution and must be formulated in the solid state. This has led to an increase in the use of lyophilized dosage forms. Lyophilization is a complicated processing method consisting of three major steps: freezing, primary drying, and secondary drying. This can lead to several formulation stability challenges including changes in ionization within the matrix, phase separation of the protein drug from added stabilizers, sufficient mobility within the system for movement of reactive species and protein side chains, and crystallization of excipients upon storage. Solid-State Nuclear Magnetic Resonance Spectroscopy (SSNMR) is used to characterize many important properties of lyophilized formulations including crystalline vs. amorphous content, polymorphic form, ionization profile, interaction between formulation components with domain sizes, and mobility within the cake matrix. In order to study ionization changes in lyophilized solids, SSNMR and UV/Vis Diffuse Reflectance spectroscopy were used. 13C-labeled fumaric, succinic, and butyric acids were added to formulations at various pH levels, and were used to quantify change in the ionization of the matrix by monitoring the ionization ratios of the carboxylic acid peaks using SSNMR. pH indicators were also added to the formulations and their ionization ratio was determined using UV/Visible Diffuse Reflectance Spectroscopy. The ionization profile in the solid state was compared with that in solution before lyophilization. A rank ordering of ionization shift was made in pharmaceutically relevant buffers. SSNMR proton relaxation times (1H T1 and 1H T1rho) for each formulation component can be compared to determine homogeneity within the lyophilized matrix. The concept of spin diffusion is used in order to determine the length scale on which the components are either homogeneous or phase separated. The domain size is typically 20-50 nm or 2-10 nm for 1H T1 and 1H T1rho, respectively. PVP and dextran polymers were phase separated on both domains for physical mixtures and lyophilized mixtures. BSA and lysozyme were both lyophilized with formulations containing sucrose, trehalose, or mannitol as the stabilizer. Mannitol crystallized, and the relaxation times showed phase separation. Sucrose and trehalose both formed homogeneous systems at both length scales when formulated in a 1:1 ratio with BSA or lysozyme. Aspartame was shown to be phase separated from trehalose. The SSNMR proton relaxation times were also used to measure the local mobility in the lyophilized matrix, as a timescale of picoseconds to nanoseconds is associated with the 1H T1 relaxation time. Mobility was monitored in formulations containing a fixed amount of sucrose and mannitol, but with a variable amount of an IgG2 protein. The 1H T1 relaxation times decreased as protein content increased. The formulations with the highest relaxation time (lowest mobility), was the most stable in accelerated temperature conditions as monitored by size exclusion chromatography and capillary isoelectric focusing. This method can be used to rank order the most stable formulations at time-zero. Anti-plasticization was also studied by formulating sorbitol in various ratios with trehalose. The 1H T1 relaxation times increased with increasing sorbitol content, while the glass transition temperature decreased. Sorbitol and trehalose glasses were also exposed to different temperature storage conditions. Sorbitol appears to promote aging, as the formulations with higher sorbitol content showed larger increases in proton relaxation time.

[ES] Las zeolitas son catalizadores ampliamente utilizados en una gran variedad de procesos químicos, por lo que la optimización de sus propiedades físico-químicas es fundamental para mejorar su aplicación en procesos de interés industrial y medioambiental. En la presente tesis doctoral se proponen diversas metodologías de síntesis directa y post-sintéticas con el fin de controlar aspectos importantes de estos materiales desde la escala microscópica hasta la molecular y atómica, así como su implicación directa en su aplicación como catalizadores y/o materiales conductores. En un primer objetivo, se estudia la influencia del tamaño de cristal y la estructura zeolítica en la transformación selectiva de CO2 hacia productos de interés como olefinas y aromáticos cuando se combina con un catalizador de hierro dopado con potasio. Por un lado, la estructura zeolítica tipo MFI (poro medio) permite maximizar la formación de productos aromáticos, mientras que las zeolitas tipo CHA (poro pequeño) y beta (poro grande) favorecen la formación de olefinas ligeras en distinta proporción. La utilización de las zeolitas ácidas nanocristalinas permite incrementar la formación de olefinas ligeras y aumentar el tiempo de vida de los catalizadores bifuncionales. Asimismo, se estudia el efecto del confinamiento a nivel molecular de diferentes estructuras zeolíticas de poro pequeño con distinto tipo de cavidad para la reacción de metanol a olefinas (MTO), pudiéndose correlacionar la selectividad hacia distintas olefinas ligeras con un parámetro teórico que depende de las dimensiones y la forma de las cavidades de los materiales microporosos. En segundo lugar, se estudia la estabilización de distintas especies metálicas en posiciones extra-red de los materiales zeolíticos, controlando su formación desde átomos individuales a clústeres y/o nanopartículas. La estructura de la zeolita CHA permite encapsular nanopartículas de Pt en el interior de sus cavidades, que son activas y estables para la reacción de oxidación de CO incluso tras tratamientos de envejecimiento a elevadas temperaturas. Por otro lado, se racionaliza la formación de nanopartículas de germanio dispersas en distintas matrices zeolíticas híbridas aprovechando la labilidad del germanio en la red cristalina de las mismas para su aplicación como materiales conductores. Se realiza una optimización de dichos materiales híbridos orgánicos-inorgánicos basados en nanopartículas de Ge mediante diversos tratamientos post-sintéticos, maximizando la dispersión de las nanopartículas y la formación de especies carbonosas para, finalmente, evaluar sus propiedades como materiales conductores. En último lugar, se utiliza esa labilidad del Ge en posiciones cristalinas de las zeolitas como estrategia para controlar a escala atómica la incorporación selectiva de distintos heteroátomos (Si y Sn). La síntesis de la estructura ITT con poros extra-grandes está limitada a bajas relaciones de Si/Ge, presentando por tanto una limitada estabilidad hidrotermal. Por ello, se lleva a cabo una sustitución isomórfica de átomos de Ge por átomos de Si, mejorando la estabilidad hidrotermal de dicho material para su aplicación en la reacción de craqueo catalítico de un gasoil de vacío, posibilitando su regeneración, y obteniendo similar selectividad a diésel y más propileno que con la muestra de origen. Por otro lado, se incorpora selectivamente Sn en la estructura BEC (polimorfo C de la zeolita beta) mediante tratamientos post-sintéticos en los defectos estructurales generados tras la eliminación de átomos de Ge, favoreciéndose la formación de sitios "abiertos" de Sn, que han demostrado ser más activos para reacciones de moléculas oxigenadas en comparación a los sitios "cerrados" de Sn. Las ventajas catalíticas del material Sn-BEC sintetizado se demuestran en la reacción Meerwein-Ponndorf-Verley-Oppenauer (MPVO), obteniéndose mayores velocidades de reacción por sitio de Sn "abierto" que con la zeolita Sn-beta(F) convencional. / [CA] Les zeolites són catalitzadors àmpliament utilitzats en una gran varietat de processos químics, per la qual cosa l'optimització de les seues propietats fisicoquímiques és fonamental per a millorar la seua aplicació en processos d'interès industrial i mediambiental. En la present tesi doctoral es proposen diverses metodologies de síntesi directa i post-sintètiques amb la finalitat de controlar aspectes importants d'aquests materials des de l'escala microscòpica fins a la molecular i atòmica, així com la seua implicació directa en la seua aplicació com a catalitzadors i/o materials conductors. Com a primer objectiu, s'estudia la influència de la grandària de cristall i l'estructura zeolítica en la transformació selectiva de CO¿ cap a productes d'interès com a olefines i aromàtics quan es combina amb un catalitzador de ferro dopat amb potassi. D'una banda, l'estructura zeolítica tipus MFI (porus mitjà) permet maximitzar la formació de productes aromàtics, mentre que les zeolites tipus CHA (porus xicotet) i beta (porus gran) afavoreixen la formació d'olefines lleugeres en diferent proporció. La utilització de les zeolites àcides nanocristalines permet incrementar la formació d'olefines lleugeres i augmentar el temps de vida dels catalitzadors bifuncionals. Així mateix, s'estudia l'efecte del confinament a nivell molecular de diferents estructures zeolítiques de porus xicotet amb diferent tipus de cavitat per a la reacció de metanol a olefines (MTO), podent-se correlacionar la selectivitat cap a diferents olefines lleugeres amb un paràmetre teòric que depèn de les dimensions i la forma de les cavitats dels materials microporosos. En segon lloc, s'estudia l'estabilització de diferents espècies metàl·liques en posicions extra-xarxa dels materials zeolítics, controlant la seua formació des d'àtoms individuals a clústers i/o nanopartícules. L'estructura de la zeolita CHA permet encapsular nanopartícules de Pt a l'interior de les seues cavitats, actives i estables per a la reacció d'oxidació de CO fins i tot després de tractaments d'envelliment a elevades temperatures. D'altra banda, es racionalitza la formació de nanopartícules de germani disperses en diferents matrius zeolítiques híbrides aprofitant la labilitat del germani en la xarxa cristal·lina de les mateixes per a la seua aplicació com a materials conductors. Es realitza una optimització d'aquests materials híbrids orgànics-inorgànics basats en nanopartícules de Ge mitjançant diversos tractaments post-sintètics, maximitzant la dispersió de les nanopartícules i la formació d'espècies carbonoses per a, finalment, avaluar les seues propietats com a materials conductors. En últim lloc, s'utilitza eixa labilitat del Ge en posicions cristal·lines de les zeolites com a estratègia per a controlar a escala atòmica la incorporació selectiva de diferents heteroàtoms (Si i Sn). La síntesi de l'estructura ITT amb porus extra-grans està limitada a baixes relacions de Si/Ge, presentant per tant una limitada estabilitat hidrotermal. Per això, es du a terme una substitució isomòrfica d'àtoms de Ge per àtoms de Si, millorant l'estabilitat hidrotermal d'aquest material per a la seua aplicació en la reacció de craqueig catalític d'un gasoil de buit, possibilitant la seua regeneració i obtenint una selectivitat similar a dièsel i més propilè que amb la mostra d'origen. D'altra banda, s'incorpora selectivament Sn en l'estructura BEC (polimorf C de la zeolita beta) mitjançant tractaments post-sintètics als defectes estructurals generats després de l'eliminació d'àtoms de Ge, afavorint-se la formació de llocs "oberts" de Sn, que han demostrat ser més actius per a reaccions de molècules oxigenades en comparació als llocs "tancats" de Sn. Els avantatges catalítics del material Sn-BEC sintetitzat es demostren a la reacció Meerwein-Ponndorf-Verley-Oppenauer (MPVO), obtenint-se majors velocitats de reacció per lloc de Sn "obert" que amb la zeolita Sn-beta(F) convencional. / [EN] Zeolites are catalysts used in many chemical processes of industrial and environmental interest. The optimization of the physicochemical properties of these materials is essential to improve their efficiency and attractiveness to current and future technologies. This doctoral thesis aimed to control relevant aspects of the zeolites at the microscopic, molecular, and atomic scale that have a direct effect on their application as catalysts and conductive materials. With this in mind, several methodologies for the direct synthesis of zeolites and several post-synthetic treatments were proposed. Firstly, the influence of crystal size and zeolitic structure on the selective transformation of CO2 towards products of interest such as olefins and aromatics is studied when combined with an iron catalyst doped with potassium. On the one hand, the MFI-type zeolitic structure (medium pore) allows the formation of aromatic products to be maximized. Meanwhile, the CHA (small pore) and BEA (large pore) zeolites favour the production of light olefins in different proportions. The use of nanocrystalline acid zeolites allows to increase the production of light olefins and increases the lifetime of the bifunctional catalysts. Likewise, the effect of confinement at the molecular level of different small-pore zeolitic structures with different types of cavities for the reaction of methanol to olefins (MTO) is studied. Using a theoretical parameter, it was finally possible to correlate the selectivity towards different light olefins with the type of cavities in the microporous materials. Secondly, the stabilization of different metallic species in extra-framework positions of the zeolitic materials is studied by controlling the formation from the individual atoms towards clusters and/or nanoparticles. The structure of the CHA zeolite allows Pt nanoparticles to be encapsulated inside its cavities, which continues being active and stable for the CO oxidation reaction even after aging treatments at high temperatures. On the other hand, the formation of germanium nanoparticles dispersed in different hybrid zeolitic matrices is rationalized by taking advantage of the lability of germanium in their crystalline framework for their application as conductive materials. The optimization of these hybrid organic-inorganic materials based on Ge nanoparticles is carried out through various post-synthetic treatments by maximizing the dispersion of the nanoparticles and the formation of carbonaceous species to evaluate their properties as conductive materials. Finally, the mentioned lability of Ge in crystalline positions is used as a strategy to control the selective incorporation of different heteroatoms (Si and Sn) at the atomic scale. The fact that the synthesis of the ITT structure with extra-large pores is limited to low Si/Ge ratios leads to reduced hydrothermal stability. Therefore, an isomorphic substitution of Ge atoms with Si atoms is carried out. It improved the hydrothermal stability of the material to be applied in the catalytic cracking of a vacuum gasoil, enabling its regeneration. Moreover, the modified material presents similar selectivity to diesel and yields more propylene as compared to the original sample. Also, Sn is selectively incorporated into the BEC structure (polymorph C of beta zeolite) through post-synthetic treatments in the structural defects generated after the elimination of Ge atoms, favouring the formation of "open" Sn sites. It has been shown that this kind of site is more active for reactions involving oxygenated molecules compared to the "closed" sites of Sn. The catalytic advantages of the synthesized Sn-BEC material are demonstrated in the Meerwein-Ponndorf-Verley-Oppenauer (MPVO) reaction. Higher reaction rates per "open" Sn site than with the conventional Sn-beta(F) zeolite were obtained. / Rodríguez Fernández, A. (2024). Diseño racional de materiales zeolíticos: efectos de confinamiento y control de centros metálicos en posiciones de red y extra-red en aplicaciones de interés [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202870

Analysis of the molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman spectroscopic technique was chosen for this purpose because it allows the identification of compounds in different states and it can give information about the molecular geometry from the analysis of the vibrational spectra. In this research the ionisation steps of relevant pharmaceutical material have been studied by means of potentiometry coupled with Raman spectroscopy; the protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the different species in the Raman spectra of aqueous salicylic acid, paracetamol, citric acid and salicylaldoxime have been identified, characterised and confirmed by numerical treatment of the observed spectral data using a multiwavelength curve-fitting program. The non-destructive nature of the Raman spectroscopic technique and the success of the application of the multiwavelength curve-fitting program demonstrated in this work have offered a new dimension for the rapid identification and characterisation of pharmaceuticals in solution and have indicated the direction of further research. The work also covers the formation of novel cocrystal systems with pharmaceutically relevant materials. The existence of new cocrystals of salicylic acid-nicotinic acid, DLphenylalanine , 6-hydroxynicotinic acid, and 3,4-dihydroxybenzoic acid with oxalic acid have been identified from stoichiometric mixtures using combined techniques of Raman spectroscopy (dispersive and transmission TRS), X-ray powder diffraction and thermal analysis. Raman spectroscopy has been used to demonstrate a number of important aspects regarding the nature of the molecular interactions in the cocrystal. Cocrystals of II salicylic acid ¿ benzamide, citric acid-paracetamol and citric acid -benzamide have been identified with similar analytical approaches and structurally characterised in detail with single crystal X-ray diffraction. From these studies the high selectivity and direct micro sampling of Raman spectroscopy make it possible to identify spectral contributions from each chemical constituent by a peak wavenumber comparison of single-component spectra (API and guest individually) and the two- component sample material (API/guest), thus allowing a direct assessment of cocrystal formation to be made. Correlation of information from Raman spectra have been made to the X-ray diffraction and thermal analysis results. Transmission Raman Spectroscopy has been applied to the study cocrystals for the first time. Identification of new phases of analysis of the low wavenumber Raman bands is demonstrated to be a key advantage of the TRS technique. / Libyan government and Misurata University

No / We describe the Δlog P method for the assessment of intramolecular hydrogen bonds (IMHBs), and show that it is not a very general method of distinguishing between molecules in which there is an IMHB and molecules in which there is no IMHB. The ‘double’ Δlog P method of Shalaeva et al. is a much more reliable method for the assessment of IMHB but requires the synthesis of a model compound and the determination of no less than four water-solvent partition coefficients. In addition, it is difficult to apply to compounds that contain more than one hydrogen bond acidic group capable of IMHB. We then describe our NMR method of assessing IMHB, based on 1H NMR chemical shifts in solvents DMSO and CDCl3. We have determined 1H NMR chemical shifts for a number of ortho-substituted anilines and show that the only compound we have studied that forms an IMHB is methyl 2-methylaminobenzoate though there is no IMHB present in methyl 2-aminobenzoate. This apparently anomalous result is supported by both MM and ab initio calculations. The NMR method is much simpler and less time consuming than other methods for the assessment of IMHB. It provides a quantitative assessment of IMHB and can be applied to molecules with more than one hydrogen bond acidic group.

An investigation of the pH, organic matter content, and cation exchange properties of the soil of the 26-year-old rotation and continuously cropped plots at Blacksburg, Virginia was carried out. Individual soil samples were taken of the eight sub-plots which represent each plot. After the chemical work had been completed, the data obtained were analyzed statistically. As a result of this investigation, the following conclusions are considered worthy of mention: Fertilizer and cropping practices which tended to increase crop yields also tended to increase soil organic matter and cation exchange capacity. There was a significant, positive correlation between organic matter content and cation exchange capacity of the soil. The organic fraction seemed to be of greater importance than the mineral fraction in contributing to the cation exchange capacity of this soil. Superphosphate, rock phosphate, muriate of potash and farm manure had or no effect on soil reaction. Ammonium sulphate caused a reduction of the pH and exchangeable calcium and magnesium and an increase in exchangeable hydrogen. The application of this fertilizer decreased exchangeable calcium but had no influence on the pH. Of the total potassium applied as muriate of potash, an average of 15 percent remained as exchangeable potassium in the upper six inches of soil. Where farm manure was applied, exchangeable calcium, magnesium, potassium, and cation exchange capacity were increased significantly. Examination of the samples and crop yield data from the check plots indicated considerable soil variation. / Master of Science