In this study, the surface acidity of Co and/or Pb doped SBA15 mesoporous catalysts were investigated by both diffuse reflectance fourier transform (DRIFT) infrared spectroscopy and transmission mode fourier transform infrared spectroscopy. Pyridine was used to identify the Br&oslash / nsted and Lewis acid sites of the surface, at room temperature. From the DRIFT spectrum typical stretching vibrations of isolated terminal silanol (Si-OH) groups were observed for all the catalysts. These silanol group bands dissappeared after pyridine adsorption, indicating that these silanol groups are acidic and serve as chemical adsorption sites for pyridine. Pyridine adsorption on these catalysts revealed that while monometallic additions did not influence the overall acidity of SBA15, in the bimetallic system, characteristic bands due to pyridine adsorption on Co2+ ions were observed.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T22:35:16Z No. of bitstreams: 1 EnedersonRossetto_TESE.pdf: 3942346 bytes, checksum: 4f772d5bb76c7fedad3ac6471650a54d (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T20:17:58Z (GMT) No. of bitstreams: 1 EnedersonRossetto_TESE.pdf: 3942346 bytes, checksum: 4f772d5bb76c7fedad3ac6471650a54d (MD5) / Made available in DSpace on 2016-06-01T20:17:58Z (GMT). No. of bitstreams: 1 EnedersonRossetto_TESE.pdf: 3942346 bytes, checksum: 4f772d5bb76c7fedad3ac6471650a54d (MD5) Previous issue date: 2015-07-31 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Os ligantes ?-diiminas 2-(fenil)amino-4-(fenil)imino-2-penteno e o 2-(2,6-dimetilfenil)amino-4-(2,6-dimetilfenil)imino-2-penteno foram combinados com o grupo alcoxisilano cloropropiltrimetoxisilano (CPTMS) e ancorado covalentemente aos suportes mesoporosos MCM-41 e SBA-15, coordenados pela intera??o com os grupos silan?is da matriz das s?licas e complexados com n?quel. Os complexos Ni-?-diimina/mesoporosos foram sintetizados para aplica??o em rea??es de oligomeriza??o do etileno e do propileno e para compara??o dos resultados entre o sistema homog?neo com o sistema heterog?neo. O suporte foi primeiramente sintetizado e calcinado. Ap?s foi realizado o ancoramento dos ligantes e posterior complexac?o do n?quel. Estes materiais foram caracterizados por v?rias t?cnicas, tais como: RMN de 1H, 13C e 29Si, DRX de baixo ?ngulo, Infra-vermelho (IR), an?lise termogravim?trica, an?lise de isotermas de adsor??o-dessor??o de N2, microscopia eletr?nica de transmiss?o (MET) e de varredura (MEV), an?lise elementar e espectroscopia de absor??o at?mica para confirmar o sucesso das s?nteses dos materiais. Ambos os complexos homog?neos e os heterogeneizados s?o ativos e seletivos para as rea??es de oligomeriza??o do etileno e do propileno. Os materiais heterogeneizados foram menos ativos que os complexos an?logos homog?neos nas rea??es de oligomeriza??o do etileno, por?m, foram mais seletivos tanto para fra??es C4 quanto para ?-C4. Nas rea??es com o propileno os complexos homog?neos promoveram ? rea??o de dimeriza??o e os complexos heterogeneizados ? rea??o de alquila??o do tolueno com o propileno. / The ?-diimine ligands 2-(phenyl)amine-4-(phenyl)imine-2-pentene and 2-(2,6- dimethylphenyl)amine-4-(2,6-dimethylphenyl)imine-2-pentene were combined with the alkoxysilane group chloropropyltrimethoxysilane (CPTMS) and covalently anchored to a mesoporous MCM-41, Al-MCM-41 and SBA-15 support, ordered by interaction with the silanols of the silica matrix and complexed with nickel. The complexes were synthesized for application in ethylene and propylene oligomerization and for comparing results between homogeneous and heterogeneous systems. The support is first synthesized, calcined, anchored to the ligand, and then subsequent complexation of nickel is realized. These materials were characterized by several techniques such as 1H, 13C and 29Si NMR, small angle XRD, Infra-red, thermogravimetric analysis, nitrogen adsorption-desorption isotherms, transmission and scanning electron microscopy, elemental analysis, and flame atomic absorption spectroscopy, to confirm the success of the synthesis. Both homogeneous and heterogeneous complexes are active and selective for the reactions of ethylene and propylene oligomerization. The heterogenized materials were less active than the homogeneous analogous complexes in the reactions of oligomerization of ethylene, however, were more selective for both C4 fractions and for ?-C4. In reactions with propylene, the homogeneous complexes promoted the dimerization reaction and the heterogenized complexes the alkylation reaction of toluene with propylene complex.Complexes were tested in recycle reactions proved to be efficient for use in large scale.

L’électrofilage est actuellement la méthode la plus utilisée pour la production de nanofibres grâce à sa simplicité, sa reproductibilité et la possibilité d’être industrialisée. Grâce à leurs propriétés particulières telles qu’un grand rapport surface-volume, une porosité inter-fibre élevée et une grande capacité d’adsorption, les nanofibres électrofilées sont de bons candidats pour de nombreuses applications telles que la filtration, les masques respiratoires, les matériaux composites, etc. Cependant, certaines applications particulières, telles que les capteurs, les systèmes d'administration contrôlée de médicaments ou les super condensateurs, exigent que les nanofibres doivent présenter des propriétés complémentaires telles que la conductivité électrique, la porosité de surface de nanofibres, l’hydrophobicité, ou d’autres propriétés particulières. Certains nanomatériaux comme les nanotubes de carbone, la silice mésoporeuse ordonnée, les argiles, ont des propriétés particulières comme la conductivité électriques élevée des nanotubes de carbone, la porosité des matériaux de silice mésoporeuse ordonnée ou de l’argile. Ces propriétés des nanomatériaux peuvent être les fonctions complémentaires cherchées. Dans notre étude, des non-tissés composés de nanofibres de polyacrylonitrile chargées par nanotubes de carbone à multi-parois (MWNT), de la montmorillonite sodique (MMT-Na) ou de la silice mésoporeuse ordonnée (de type SBA-15), sont produits par électrofilage. Les résultats montrent que l’insertion de MWNT rend le non-tissé conducteur en augmentant la conductivité électrique volumique par six ordres de grandeur (de ~ 2×10-12 à ~ 3×10-6 S/m) avec un très faible seuil de percolation de 0.5 % massique. Lorsque le non-tissé est soumis à une compression, la conductivité électrique volumique augmente en augmentant la pression (jusqu’à ~ 2 kPa). Ces non-tissés conducteurs sont très intéressants pour le développement des capteurs à faible amplitude. Les résultats montrent aussi que l’accessibilité des pores des particules inorganiques (c’est-à-dire, les mésopores de SBA-15 et l’espace interfoliaire de MMT-Na) insérées dans la structure nano fibreuse est encore possible. Il a été trouvé que plus de 50% des mésopores de SBA-15 insérées sont encore accessibles quelles que soit les conditions de l’électrofilage et la fraction massique de SBA-15. En outre, l’insertion de ces particules inorganiques apporte plus de stabilité thermique aux nanofibres composites. / Electrospinning is the most common method for the production of nanofibres due to its simplicity, repeatability, and the ability to be scaled up. Owing to their advanced properties like the high surface-to-volume ratio, high interfibrous porosity, high adsorption capacity, etc. electrospun nanofibers are good candidates for many applications such as filtration, respiratory masks, composite materials and others. However, some specific applications including sensors, controlled drug delivery systems, supercapacitors, etc. still require complimentary functions that do not exist in pristine nanofibers in their basic structure like the electrical conductivity, surface porosity of the nanofibers, hydrophobicity, and others.Nanomaterials like carbon nanotubes, ordered mesoporous silica, layered silicate, etc. are characterized by particular properties like the high electrical conductivity of carbon nanotubes, the porosity of ordered mesoporous silica or layered silicate. These particular properties of nanomaterials can fulfill of the targeted functions.In our study, nonwovens made from nanofibers of polyacrylonitrile incorporated with multiwalled carbon nanotubes (MWNT), layered silicate type Na-montmorillonite (Na-MMT) or ordered mesoporous silica type SBA-15 are successfully produced by electrospinning.Results reveal that the incorporation of MWNT altered the electrical state of the nonwoven from insolent to conductor where the volume electrical conductivity increased by six order of magnitude (from ~ 2×10-12 to ~ 3×10-6 S/m) with a very low percolation threshold of about 0.5 wt%. The application of mechanical pressure to the conductive nonwoven causes an increase in the volume electrical conductivity with the increase of the applied pressure (up to ~ 2 kPa). Such conductive nonwoven is very interesting for the development of sensor with low amplitude.Results also show that accessibility of the pores of the inorganic particles (i.e. mesopores of SBA-15 and interlayer space of Na-MMT) incorporated into the nanofibers is still possible. It is found that at least 50% of SBA-15 mesopores are still accessible whatever is the electrospinning conditions and SBA-15 mass fraction. In addition, the incorporation of the studied inorganic particles yields higher thermal stability for the composite nanofibers.