CORREIA, L. M. Fe2O3 ou Co3O4 suportados em sílicas mesoporosas modificadas com NH4F e Ti para adsorção de benzotiofeno e reação de oxidação catalítica seletiva parcial de H2S a S. 2017. 233 f. Tese (Doutorado em Engenharia Química)-Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2017. / Submitted by Hohana Sanders (hohanasanders@hotmail.com) on 2017-10-03T18:25:12Z No. of bitstreams: 1 2017_tese_lmcorreia.pdf: 3519700 bytes, checksum: 80fb75064a529c39bee1587404389fd8 (MD5) / Approved for entry into archive by Marlene Sousa (mmarlene@ufc.br) on 2017-11-08T14:44:39Z (GMT) No. of bitstreams: 1 2017_tese_lmcorreia.pdf: 3519700 bytes, checksum: 80fb75064a529c39bee1587404389fd8 (MD5) / Made available in DSpace on 2017-11-08T14:44:39Z (GMT). No. of bitstreams: 1 2017_tese_lmcorreia.pdf: 3519700 bytes, checksum: 80fb75064a529c39bee1587404389fd8 (MD5) Previous issue date: 2017-07-31 / The presence of sulfur (S) in automotive fuels must be retrain, once it generates air pollution and promotes damage to the motor (corrosion), affecting the health of living beings. The conventional process of hydrodesulfurization (HDS) for sulfuric compounds removal, used by petrochemical industries, generates large amount of H2S, which can be used in selective partial oxidation reaction of H2S to S. The HDS treatment process is not effective to remove refractory compounds at low concentrations of S, making polish techniques, such as adsorption, necessary due to environmental constraints increase. This situation has led to a need of deeper research in the area of sulfur compounds removal in fossil fuels (gas and diesel). Thus, the development of methodologies to prepare and characterize new adsorbents with high sulfur removal are necessary. The adsorption of BT (standard organic molecule contained in gas and diesel) was investigated using a regular mesoporous silica SBA-15 type and modified with NH4F, and impregnated with Fe and Co respectively. The experiments were done in batch, with different initial BT concentrations (3-15 mmol.L-1) at different temperatures (30 °C, 40 °C and 50 °C). In the second part of the research, the H2S was partially oxidized to S and SO2 using a tubular fixed bed catalytic reactor, containing mesoporous silica HMS, SBA-15, and MCM-41 modified with NH4F and Ti, and respectively Fe2O3 and Co3O4. The catalytic tests were conducted at 180 °C and 170 oC. Reactional conditions were a catalyst mass of 100 mg (40-60 mesh), operating with a 125 mL.min-1 total flow, with molar ratio H2S/Air/He (1/5/94). The brackets, adsorbents and active phases of mesoporous catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), adsorption and desorption isotherms at -196°C, x-ray photoeletronic spectroscopy (XPS), Fourier transform infrared (FTIR), Elemental analysis (CHNS) and spectroscopy of UV-visible region. The results show that mycotoxin adsorbents are promising for the hydrodesulfurization process for BT removal, especially, the sample (15Co/SBA-15/NH4F). All the prepared catalysts are active and promising for the elementary S production. The most stable catalyst was 15Fe/MCM-41, obtaining conversion values of H2S (89.72%), selectivity of S (96.19%), and selectivity of SO2 (3.81%) at 180 °C and 360 min of reaction time in the H2S to S selective oxidation partial reaction in gas phase / A presença de enxofre (S) nos combustíveis automotivos deve ser combatida, uma vez que gera a poluição atmosférica e traz prejuízos ao motor (corrosão), afetando também à saúde dos seres vivos. O processo convencional de hidrodessulfurização (HDS) para remoção dos compostos de S, utilizado pelas indústrias petroquímicas, gera elevada quantidade de H2S, o qual pode ser utilizado na reação de oxidação seletiva parcial de H2S a S. O processo de tratamento por HDS não é eficaz para remoção de compostos refratários em baixas concentrações de S, o que torna necessário a técnicas de acabamento como a adsorção, devido a um aumento nas restrições ambientais. Essa situação tem levado a uma necessidade de maiores pesquisas na área de remoção de sulfurados nos combustíveis (gasolina e diesel). Assim, busca-se desenvolver metodologias para preparar e caracterizar novos adsorventes com elevada capacidade de remoção de enxofre. A adsorção de BT (molécula orgânica modelo contida na gasolina e diesel) foi investigada utilizando-se sílicas mesoporosas do tipo SBA-15 e modificadas com NH4F, e impregnadas respectivamente com Fe e Co. Os experimentos foram feitos em batelada, com diferentes concentrações iniciais de BT (3-15 mmol/L) e temperaturas distintas (30 oC, 40 oC e 50 oC). Na segunda parte da pesquisa o H2S foi parcialmente oxidado a S e SO2 utilizando um reator catalítico de leito fixo do tipo tubular, contendo sílica mesoporosa do tipo HMS, SBA-15, e MCM-41 modificadas com NH4F e Ti, e respectivamente Fe2O3 e Co3O4. Os testes catalíticos foram conduzidos a uma temperatura de reação de 180 ºC e 170 oC. As condições reacionais foram massa do catalisador de 100 mg (40-60 mesh), operando com uma vazão total de 125 mL min-1, com razão molar H2S/Ar/He (1/5/94). Os suportes, adsorventes e as fases ativas dos catalisadores mesoporosos foram caracterizados por difração de raios-X (DRX), microscopia eletrônica de transmissão (MET), isotermas de adsorção e dessorção a -196 oC, espetroscopia fotoeletrônica de raios-X (XPS), infravermelho com transformada de Fourier (FTIR), análise elementar (CHNS) e espectroscopia da região do UV-visível. Os resultados demonstram que os adsorventes são promissores para o processo de hidrodessulfurização para a remoção da molécula de BT, especialmente, a amostra (15Co/SBA-15/NH4F). Todos os catalisadores preparados são ativos e promissores para produção de S elementar. O catalisador mais estável foi 15Fe/MCM-41, obtendo-se valores de conversão de H2S (89,72%), seletividade a S (96,19%), e seletividade a SO2 (3,81%) na temperatura de 180 oC e tempo reacional de 360 min na reação parcial de oxidação seletiva de H2S a S em fase gás

Made available in DSpace on 2014-06-11T19:35:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-12Bitstream added on 2014-06-13T18:46:22Z : No. of bitstreams: 1 rocha_la_dr_araiq.pdf: 3758896 bytes, checksum: 8f9b1dddc8f92a0c77915bd317de357f (MD5) / Partículas esféricas de sílica mesoporosa foram obtidas a partir da síntese “template” pelo processo de pirólise de aerossol. O processo foi otimizado para a obtenção de materiais mesoporosos sem resíduos orgânicos e preparados em uma única etapa, eliminando assim, a longa etapa de remoção do surfactante na metodologia tradicional (tratamento térmico ou extração soxhlet, podendo durar dezenas de horas). A otimização do processo de pirólise de aerossol proposta nesta tese reduziu este tempo para apenas alguns minutos. Os materiais apresentaram uma área superficial (BET) de até 1028 m2 .g-1 , com volume de poros (BJH) de 0,58 cm3 .g-1 . Os difratogramas de raios-X indicaram um alto grau de organização com um arranjo hexagonal de poros, confirmado também pela microscopia eletrônica de transmissão. Além disto, bandas características de grupos orgânicos não foram observadas nos espectros de absorção na região do infra-vermelho para as amostras obtidas acima de 600ºC. Amostras dopadas com íons Eu3+ também foram preparadas durante a tese. A análise por espectroscopia de luminescência, para íons Eu3+ , indicou que o íon está encapsulado nos canais mesoporosos sem prévia modificação química da matriz. Posteriormente, moléculas de 1,10- Fenantrolina foram coordenadas ao íon Eu3+ aumentando a faixa espectral de excitação do íon (efeito antena). Além disto, partículas luminescentes também foram obtidas pela incorporação do complexo Eu(fod)3 ou rodamina-B nos poros das matrizes. Finalmente, testes de recobrimento (core shell, SiO2 mesoporoso-SiO2) das partículas luminescentes foram realizados e os resultados indicaram que independentemente da espessura obtida pelo processo de recobrimento, o grau de organização dos poros e a fotoluminescência não sofreram alterações / Spherical mesoporous silica particles were obtained using the template synthesis by spray pyrolysis process. The process was optimized for the preparation of the mesoporous materials in one-pot route without organic residues, eliminating thus, the long process of removal of the surfactant, usually used in the available methods (heat treatment or soxhlet extraction, which require several hours or days). The one- pot route proposed in this thesis reduced the extraction process to only a several minutes. These materials presented a surface area value (BET) of 1028m2 .g-1 and pore volume (BJH) was 0,58 cm3 .g-1 . The X-ray diffraction patterns and the transmission electronic micrographs show an ordered typical p6mm 2D hexagonal mesostructure. Characteristics bands of organic groups were not observed in the infra-red absorption spectra for the samples obtained at 600ºC. Moreover, SiO2 mesoporous doped with Eu3+ ions were also prepared. Luminescence data suggest that the Eu3+ ions were successful encapsulated into the channels of mesoporous silica without any preliminary chemical modification of the matrix. Moreover, extra ligands such as 1,10-Phenantroline can be further coordinated, increasing the spectral range excitation (antenna effect). Furthermore, luminescent particles were also prepared by the wet impregnation of Eu(fod)3 complex and rhodamine-B molecules. Finally, tests of coating (core shell, SiO2 mesoporous-SiO2) of luminescent particles had been carried through and the The results obtained show spherical shape and the observation of a highly ordered hexagonal array of mesochannels further confirms the 2D hexagonal p6m structure. Luminescence results reveal that rhodamine-B has been successfully encapsulated into the channels of mesoporous particles. Silica coating has been observed in TEM measurements

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A exigÃncia de um maior controle na emissÃo de poluentes de automÃveis, com uma reduÃÃo na emissÃo de enxofre, tem levado a um intenso esforÃo de pesquisas sobre tÃcnicas de remoÃÃo de sulfurados nos combustÃveis. Nos Ãltimos anos, a adsorÃÃo à vista como uma tÃcnica alternativa adequada para atingir os nÃveis de dessulfurizaÃÃo das correntes das unidades de processo de hidrodessulfurizaÃÃo (HDS). O processo HDS à muito eficiente na remoÃÃo de mercaptanas e dissulfetos, porÃm maior severidade seria necessÃria para converter as molÃculas cÃclicas de enxofre, tais como tiofenos e benzotiofenos. Devido ao tamanho volumoso destes compostos refratÃrios de enxofre, adsorventes mesoporosos sÃo vistos como mais adequado para a adsorÃÃo do que sÃlidos microporosos convencionais, tais como zeÃlitas. A dessulfurizaÃÃo por adsorÃÃo com adsorventes modificados e seletivos à um processo alternativo promissor com relaÃÃo à hidrodessulfurizaÃÃo convencional por se tratar de um processo que nÃo necessita de condiÃÃes severas de operaÃÃo que comprometam a octanagem da gasolina e o custo final de operaÃÃo. Neste trabalho foi realizado um estudo de remoÃÃo de enxofre a partir de soluÃÃes de benzotiofeno em iso-octano, utilizando os adsorventes SBA-15 e SBA-15/PdCl2. Ãrea superficial BET, volume de poros e diÃmetro de poro dos materiais mesoporos, SBA-15 e SBA-15/PdCl2, foram medidos. A adsorÃÃo do benzotiofeno em iso-octano foi avaliada atravÃs do estudo dinÃmico usando uma coluna de leito fixo em escala de laboratÃrio, utilizando os adsorventes SBA-15 e SBA-15/PdCl2. Para a SBA-15/PdCl2 o estudo de adsorÃÃo em leito fixo foi realizado em quatro temperaturas: 25, 35, 45 e 60ÂC. Curvas de breakthrough foram simuladas de acordo com um modelo matemÃtico que considera as seguintes hipÃteses: operaÃÃo isotÃrmica, fluxo com dispersÃo axial, taxa de fluxo constante, resistÃncia à transferÃncia de massa externa Ãs partÃculas (filme) desprezÃvel, transferÃncia de massa descrita por uma aproximaÃÃo de forÃa motriz linear (LDF), isoterma de adsorÃÃo linear e equilÃbrio de adsorÃÃo atingido instantaneamente na superfÃcie externa das partÃculas adsorventes. Os resultados confirmaram a eficiÃncia da SBA-15/PdCl2 para a utilizaÃÃo em processos de adsorÃÃo de compostos sulfurados. / The demand of a larger control in the emission of pollutants from automobiles, with a reduction in the emission of sulfur, has led to an intense research effort on techniques of sulfur removal from fuels. In the last few years, adsorption is thought to be a suitable polishing technique to achieve a deep desulfurization of streams from hydrodesulfurization (HDS) units. The HDS process is very efficient in the removal of mercaptans and disulfides but higher severity would be required to convert cyclic sulfur molecules, such as tiophenes and benzotiophenes. Due to the bulky size of these refractory sulfur compounds, mesoporous adsorbents are thought to be best suited for adsorption than conventional microporous solids, such as zeolites. The desulfurization by adsorption with modified and selective sorbents is a promising alternative process when compared to the conventional hydrodesulfurization once that process does not need severe conditions of operation which compromise the octane of the gasoline and the final cost of operation. In this present work, a study was coducted to remove sulfur from benzothiophene solutions in isooctante, using the adsorbent SBA-15 and SBA-15/PdCl2. BET surface area, pore volume and pore diameter of SBA-15 and SBA-15/PdCl2 mesoporous materials were measured. Adsorptive desulfurization in benzothiophene/isooctane mixture was carried trough dynamic study using a column of fixed bed in laboratory scale, using sorbents SBA-15 and SBA-15/PdCl2. The adsorption study using SBA-15/PdCl2 was carried on four temperatures: 25, 35, 45 and 60ÂC. Breakthrough curves were simulated according to a mathematical model that assumes the following hypotheses: isothermal operation; flow with axial dispersion; constant fluid flow rate; negligible external film resistance to mass transfer; internal mass transfer described by LDF approximation; linear adsorption isotherm and equilibrium reached instantaneously at the external surface of adsorbent particles. The results confirmed the efficiency of SBA-15/PdCl2 for use in adsorption process of sulfur compounds.

The objective of this work was to synthesize functionalized mesoporous silsesquioxanes with high concentrations of amine groups. During typical sol-gel syntheses, these materials are obtained by co-condensation of organic precursors with suitable linkers, such as tetraethoxysilane, necessary to prevent the mesoporous structure from collapsing. Thus, concentrations of amine groups in organosilicas usually do not exceed 2.7-3.4 mmol g -1. The use of bridged bis-trimethoxysilanes, however, allowed formation of mesoporous materials with no linker. Polycondensation of bis-trimethoxysilanes containing amine groups was conducted in acidic, neutral and basic media, resulting in high yields of solid bridged silsesquioxanes. Gelation occurred quickly if no acid or base was added to the reaction mixture. The hybrid organic/ inorganic nature of obtained materials was confirmed by FT-IR and MAS CP NMR spectroscopy. Elemental analysis showed that amino group concentration in the products was 3.3-4.1 mmol g -1. Measurement of particle size distribution confirmed that choice of reaction media significantly affects particle sizes and agglomeration degrees, with the largest agglomerates (up to 50 μm) formed in basic media. A morphology study, using smallangle X-Ray scattering, displayed two-level fractal structures composed of aggregated 6.5-10.5 nm particles. Reactions in the presence of a surfactant resulted in formation of mesoporous structures. Furthermore, the obtained bridged silsesquioxanes were thermally stable down to 260 °C, but could reversibly absorb water and CO 2 at temperatures below 120 °C. Thus, condensation of the bridged precursor without a linker resulted in formation of a highly functionalized mesoporous material.

Abstract: Silica gels containing embedded heteropolyacids were synthesized in acidic media by co-condensation of tetraethoxysilane with phosphotungstic or phosphomolybdic acids using the sol-gel technique. Surfactants dodecylamine, sodium dodecylsulfate, trimethylstearylammonium chloride, and Pluronic P123 were used as templates. The effect of the synthesis conditions on their structure and morphology was studied. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin structures in fourier transform infrared spectroscopy spectra along with absence of X-ray diffraction patterns of crystalline heteropolyacids confirmed their fine incorporation into silica network. Particle sizes of modified materials were 500–1100 nm except for the W-containing sample obtained with trimethylstearylammonium chloride, which was significantly lower. This unusual effect was attributed to stabilization of primary silica nanoparticles by interactions between the surfactant and heteropolyacid. High ratio heteropolyacid/tetraethoxysilane resulted in partial loss of porosity. Obtained results might be used for optimization of synthesis of effective catalysts and adsorbents containing heteropolyacids in mesoporous structure. Graphical Abstract: [InlineMediaObject not available: see fulltext.]

Les nanosciences représentent, actuellement, un domaine de recherche en pleine expansion grâce aux nombreuses applications auxquelles elles peuvent être associées, et en particulier à la course à la miniaturisation des systèmes. De plus, il a rapidement été montré que les propriétés physico-chimiques des matériaux à l’échelle nanométrique sont modifiées parfois de manière drastique, à cause par exemple des effets quantiques apparaissant à des tailles aussi petites, mais aussi en raison des effets de confinement. Le confinement de molécules ou de particules à l’échelle nanoscopique nécessite donc la fabrication de matériaux hôtes possédant ce qu’il convient d’appeler des sites de confinement, c’est-à-dire des sites possédant une taille voisine de celle du système à insérer. Ce type de matériau est désormais relativement connu, et deux familles monopolisent l’intérêt, à savoir la silice mésoporeuse, aussi et récemment utilisé, les verres bioactifs à base de silice ayant des caractéristiques contrôlées qui constituent des matériaux hôtes de confinement qui peuvent être immergés dans des fluides complexes tel que le plasma sanguin synthétique. Pour réaliser ces travaux on a besoins d’appliquer plusieurs techniques de caractérisations telles que la diffusion des Rayons X et des Neutrons, la Microscopie Electronique à Balayage et à Transmission, la spectroscopie Infrarouge à Transformé de Fourier etc...De plus, ces dernières années, des systèmes microfluidiques ont été utilisés pour élaborer des émulsions doubles, des microcapsules ou des microparticules, avec la particularité d’obtenir des populations très monodisperses par rapport à celles obtenues avec des techniques plus traditionnelles et de morphologie contrôlée. Dans le domaine pharmaceutique, ces capacités sont particulièrement intéressantes pour la synthèse de médicaments à libération contrôlée. Elles permettent d’obtenir des particules monodisperses de polymère encapsulantes pour lesquelles l’effet de relargage brutal est diminué et qui possèdent des vitesses de relargage plus lentes que celles observées avec des procédés de fabrication conventionnels. / Nanoscience currently represent a growing area of research through the many applications for which they may be associated, particularly in the race for miniaturization of systems. In addition, it was quickly demonstrated that the physico-chemical properties of nanoscale materials are sometimes changed drastically, for example because of quantum effects occurring at sizes as small, but also because of confinement effects .Confinement of molecules or particles at the nanoscale therefore requires the manufacture of host materials with what to call containment sites, that is to say, sites with a size close to that of the system insert. This type of material is now relatively well known, and two families monopolize the interest, ie the mesoporous silica, and also recently used bioactive glasses based on silica having controlled characteristics that are host materials containment can be immersed in complex fluids such as synthetic blood plasma.To do this work several characterization techniques we need to apply, including the spread of X-rays and neutrons, the Scanning Electron Microscopy and Transmission, Infrared spectroscopy Transformed Fourier etc ...Moreover, in recent years, microfluidic systems were used to prepare double emulsions, microcapsules or microparticles, with the particularity to obtain highly monodisperse populations compared to those obtained with more traditional and controlled morphology techniques. In the pharmaceutical field, these capabilities are particularly interesting for the synthesis of controlled release to drugs. They enable polymer monodisperse particles encapsulating why the sudden release effect is decreased and have slower release rates than those observed with conventional manufacturing processes

Yes / The synthesis of metal–organic frameworks with large three-dimensional channels that are permanently porous and chemically stable offers new opportunities in areas such as catalysis and separation. Two linkers (L1=4,4′,4′′,4′′′-([1,1′-biphenyl]-3,3′,5,5′-tetrayltetrakis(ethyne-2,1-diyl)) tetrabenzoic acid, L2=4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid) were used that have equivalent connectivity and dimensions but quite distinct torsional flexibility. With these, a solid solution material, [Zr6O4(OH)4(L1)2.6(L2)0.4]⋅(solvent)x, was formed that has three-dimensional crystalline permanent porosity with a surface area of over 4000 m2 g−1 that persists after immersion in water. These properties are not accessible for the isostructural phases made from the separate single linkers. / Financial support from EPSRC under EP/H000925, access to the HPC service ARCHER via EP/L000202. S.N. thanks the EU for a Marie Curie fellowship (PIEF-GA-2010-274952). C.M.-G. thanks the Spanish MINECO for a Ramón y Cajal Fellowship (RYC-2012-10894).

By replacing the intercalation electrode with a porous electrode and allowing lithium to react directly with O₂ from the air, the new rechargeable Li/O₂ battery system was studied. The porous cathode is comprised of carbon, catalyst and binder. The effect of every component was investigated. The catalyst was believed to play an important role in the performance of the electrode. A number of potential materials have been examined as the catalyst for the O₂ electrode. It suggests that the nature of the catalyst is a key factor controlling the performance of the O₂ electrode. Several catalysts based on first row transition metal oxides each with three different morphologies, bulk, nanoparticulate and mesoporous were studied. The influence of the morphology on the discharge and charge voltage, discharge capacity and cyclability were examined. Among all the catalysts studied, α-MnO₂ nanowires was found to be the best candidate. The reversible capacities of 3000 mAhg⁻¹(normalised by the mass of carbon) or 505 mAhg⁻¹ (based on the total mass of cathode + O₂ ) was obtained. Some of other factors, such as type of carbon, type of binder, type of electrolyte, the construction of cathode and the modification of the catalyst were also investigated, even just in the early stage. Capacity fading during cycling is the main problem in all the cases. A number of experiments were carried out to understand and attempt to avoid the fading problem. After successful synthesis of mesoporous α-Fe₂O₃ with unique properties (by Jiao et al.), the application of these materials in conventional Li battery was studied. Mesoporous α-Fe₂O₃ with ordered walls, mesoporous α-Fe₂O₃ with disordered walls and Fe₂O₃ nanoparticles were examined. It was also applied to examine the different factors that influence the rate of conversion electrodes, i.e., Li⁺ and e⁻ transport to and within the particles, as well as the rate of the two-phase reaction, demonstrating that for this conversion reaction electron transport to and within the particles is paramount.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In this thesis the synthesis of a range of model and siloxane functionalized salicylaldimine ligands and [N-(n-propyl)-(2-pyridyl)] diimine ligands are described. The functionalized ligands were obtained by the reaction of salicylaldehyde and 2-pyridinecarboxaldehyde with 3-aminopropyltriethyoxysilane. All ligands were characterized by FT-IR and 1H NMR spectroscopy. The salicylaldimine ligands were reacted with either Cu(II) or Pd(II) salts to form both the model and functionalized Cu(II) and Pd(II) complexes. The Cu(II) complexes were characterized using FT-IR, EPR and UV-VIS spectroscopy while the Pd(II) complexes were characterized using FT-IR, 1H NMR and 13C{1H} NMR spectroscopy. The diimine ligands were reacted with Cu(II) salts to form functionalized pyridinyl complexes which were characterized used FT-IR spectroscopy. Two mesoporous silica supports, MCM-41 and SBA-15 were synthesized. The siloxane functionalized salicylaldimine Cu(II) and Pd(II) complexes were immobilized onto these supports to produce heterogenized catalysts. These catalysts were characterized using a range of solid-state techniques: BET nitrogen adsorption/desorption, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), ICP-AES, and powder X-ray diffraction (XRD) analysis. The powder XRD and SEM analysis showed that the structural integrity of the catalyst supports was kept intact during the immobilization process. BET analysis and ICP-AES showed that the complexes had been attached to the silica supports. Both the model complexes and heterogenized catalyst systems were tested in the oxidation of benzyl alcohol to benzaldehyde. The model copper catalyst showed high activity in this reaction with molecular oxygen used as oxidant and the (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical as co-oxidant. The immobilized copper complexes showed low activity in the same reaction. This was attributed to steric hindrance around the active site dye to its entrapment with the silica matrix thus hindering the formation of a key intermediate in the oxidation cycle due to steric hindrance. The palladium complexes were not active in the oxidation reaction when molecular oxygen was used as oxidant, but showed slight activity when hydrogen peroxide was used. / AFRIKAANSE OPSOMMING: In hierdie tesis word die sintese van ‘n reeks model sowel as gefunksioneerde salisielaldemien ligande en [N-(n-propiel)-(2-piridiel)] di-imien ligande beskryf. Die gefunksioneerde ligande is verkry deur die reaksie van salisielaldehied en en 2-piridienaldehied met 3-aminopropieltriëtoksiesilaan. Al die ligande is gekarakteriseer deur FT-IR en 1H-KMR spektroskopie. Die salisielaldimien ligande is met óf Cu(II) óf Pd(II) soute reageer om beide die model en gefunksioneerde Cu(II) en Pd(II) komplekse te vorm. Die Cu(II) komplekse is gekarakteriseer deur FT-IR, EPR en UV-Vis spektroskopie terwyl die Pd(II) komplekse deur FT-IR, 1H-KMR en 13C{1H}-KMR spektroskopie gekarakteriseer is. Die di-imien ligande is met Cu(II) soute reageer om gefunksioneerde piridinielkompekse te vorm wat deur FT-IR spektroskopie gekarakteriseer is. Twee mesoporeuse silika draers, MCM-41 en SBA-15 is gesintetiseer. Die siloksaan-gefunksioneerde salisielaldemien Cu(II) en Pd(II) komplekse is op hierdie draers geimobiliseer om geheterogeniseerde katalisatore te vorm. Hierdie katalisatore is gekarakteriseer deur van ‘n wye reeks vaste toestand tegnieke gebruik te maak: BET stikstof adsorpsie/desorpsie, skandeer elektron mikroskopie (SEM), termiese gravimetriese analise (TGA), ICP-AES en poeier-XRD analise. Die poeier-XRD en SEM analisies het aangetoon dat die strukturele integriteit van die katalisator draers behoue gebly het tydens die immobiliseringsproses. BET analise en ICP-AES het aangetoon dat die komplekse aan die silika draers geheg is. Beide die model komplekse en geimobiliseerde katalisators is getoets in die oksidasie van bensielalkohol na bensaldehied. Die model Cu(II) katalisator het hoë aktiwiteit in hierdie reaksie getoon met molekulêre suurstof as oksideermiddel en die (2,2,6,6-tetrametielpipiridien-1-iel)oksiel radikaal as ko-oksideermiddel. Die geimobiliseerde Cu(II) komplekse het lae aktiwiteit in dieselfde reaksie getoon. Dit is toegeskryf aan steriese hindernis rondom die aktiewe sentrum as gevolg van die verstrikking binne die silika matrys, wat die vorming van ‘n belangrike tussentoestand in die oksidasie-siklus verhinder. Die Pd(II) komplekse was nie aktief in die oksidasie-reaksie in die geval waar molekulêre suurstof as oksideermiddel gebruik is nie, maar het effense aktiwiteit getoon waneer waterstofperoksied gebruik is. / Sasol

Στην παρούσα μεταπτυχιακή εργασία ειδίκευσης περιγράφεται η σύνθεση και ο χαρακτηρισμός νέων μεσοπορωδών βιοενεργών υλικών. Παρουσιάζονται οι συσχετιζόμενες με τα πορώδη/μεσοπορώδη υλικά έννοιες, οι ιδιότητες τους και διάφοροι τρόποι σύνθεσης τους. Εν συνεχεία, αναλύονται θέματα βιουλικών, δίνοντας έμφαση στις βιοϋάλους και τις ιδιότητες τους, και ειδικότερα στη βιονεργότητα, που αποτελεί την πιο χαρακτηριστική ιδιότητα αυτών, ενώ δίνεται έμφαση, επίσης στις διάφορες μεθόδους που χρησιμοποιούνται για την σύνθεση τους. Στην συνέχεια αναλύονται οι τεχνικές που χρησιμοποιήθηκαν για το χαρακτηρισμό των προαναφερθέντων υλικών καθώς και ο τρόπος λειτουργίας της κάθε τεχνικής. Επίσης, γίνεται αναφορά στα διαφορετικά χαρακτηριστικά των υλικών που μπορούν να μελετηθούν για κάθε τεχνική ξεχωριστά. Στο τελευταίο κεφάλαιο παρουσιάζεται αναλυτικά η διαδικασία διεξαγωγής των πειραμάτων, οι διάφοροι τρόποι σύνθεσης που χρησιμοποιήθηκαν, καθώς και σχολιασμός των αποτελεσμάτων. Τέλος, παρουσιάζονται τα συμπεράσματα που προέκυψαν από τα πειραματικά αποτελέσματα για την παρούσα μεταπτυχιακή εργασία. Επίσης γίνεται αναφορά και σε μελλοντικές κατευθύνσεις που περιλαμβάνουν την χρήση αυτών των υλικών σε σύνθετα υλικά για παλμική εναπόθεση με Laser και τεχνικές εναπόθεσης λεπτού υμενίου. / In this master thesis the synthesis and characterization of novel bioactive mesoporous materials is being reported. The notions related to porous/mesoporous materials, their properties and various synthetic methods are being discussed. Subsequently, the notion of “biomaterials” is further analyzed, focusing on bioglasses and their properties. The meaning of bioactivity is also analyzed as the most characteristic feature of bioglasses while various methods used for the synthesis of these are discussed. Following the techniques used to characterize these materials as well as the operating mode of each technique is discussed. In the last chapter, the experimental processes are reported as well as the results are being discussed. Finally, the conclusions of all the experiments and analysis are reported. Also, future directions include the usage of these materials in composite materials for laser ablation and thin film deposition techniques are mentioned.