Plastic materials are widely used throughout the world due to their low prices and easy processing methods. A serious problem of environmental pollution is brought with the widespread use of these materials due to their non-biodegradabilty. For this reason, plastic materials are degraded into lower molecular weight liquid and gaseous products which are potential raw materials and fuels for petrochemical industry. The use of catalysts enhances the formation of more valuable hydrocarbons at lower reaction temperatures and residence times. In this study, aluminum containing MCM-41 and tungstophosphoric acid (TPA) loaded SBA-15 materials were synthesized by impregnation of Al and TPA into hydrothermally synthesized MCM-41 and SBA-15, respectively to be used in catalytic degradation of polyethylene. Al was incorporated into MCM-41 framework with different Al/Si ratios using aluminum triisopropylate as the aluminum source and TPA was incorporated to the porous framework of SBA-15 with different W/Si ratios, using tungstophosphoric acid hydrate as the acid source. From XRD analysis, it was observed that introducing acidic compounds did not cause deformations in the regularity and by EDS analysis, it was found out that at lower loadings, acidic compounds were introduced more effectively for MCM-41 materials. Nitrogen adsorption-desorption isotherms showed that the synthesized materials exhibited type IV isotherms. SEM and TEM pictures showed the hexagonal regularly ordered structure of SBA-15 and MCM-41 materials. FTIR analysis of the pyridine adsorbed synthesized materials revealed the existence of Lewis and Br&oslash / nsted acid sites in the synthesized materials. From TGA analysis it was observed that aluminum impregnated MCM-41 samples reduced the temperature of the degradation reaction significantly and TPA loaded SBA-15 samples reduced activation energy of the reaction effectively. In the degradation reaction system, non-catalytic and catalytic degradation experiments of polyethylene were performed. In non-catalytic degradation and catalytic degradation reactions carried out using aluminum containing MCM-41 materials, selectivity of C3 and C4 hydrocarbon gases was high and in catalytic degradation reactions carried out using TPA impregnated SBA-15 materials, selectivity of ethylene was high. In the liquid analysis of non-catalytic degradation reactions, it was observed that the product distribution was mainly composed of hydrocarbons greater than C18. The use of aluminum loaded MCM-41 and TPA loaded SBA-15 materials resulted in a liquid product distribution in the range of C5-C14, which is the hydrocarbon range of gasoline fuel.

There are several studies in order to control drug delivery, decrease the toxicity of drugs and also for novel biomedical applications. It is necessary to be able to control the release of the drug within the body by using drug delivery systems. Mesoporous silica compounds have only been discovered twenty years ago and they have already attracted many researchers to study these materials for several applications. SBA-15 particles have a highly ordered regular structure and are a good matrix for guest-host applications. The aim of this study is to be able to address whether the surface functionalization of SBA-15 samples would improve the loading of a drug into these particles. The synthesized SBA-15 particles were surface functionalized by post - grafting synthesis method in order to be used as carrier materials for drug delivery. Amoxicillin was used as a model drug. These mesoporous materials have been characterized using X-ray diffraction (XRD), small-angle X-ray spectroscopy (SAXS), fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), N2 adsorption/ desorption, solid-state silicon nuclear magnetic resonance (Si-NMR), high-performance liquid chromatography (HPLC), ultra-violet (UV) spectroscopy, elemental and thermo gravimetric analysis (TGA). The effect of concentration difference and the type of alkoxysilanes used for the functionalization have been discussed in terms of loading amoxicillin and controlling the delivery. Drug delivery systems have many further applications that still need to be investigated in areas such as neurosciences, cancer and biomedical engineering.

In this study, catalytic activity of the Co and/or Pb-SBA-15 mesoporous catalysts in methane partial oxidation reaction was investigated. By using sol-gel, incipient wetness impregnation and post grafting method, SBA-15 samples are incorporated with Co and/or Pb at different weight loadings to provide a controlled geometry in nanometer scale. The characterization of the synthesized samples was done by XRD, N2 adsorption isotherms, FTIR, TEM images, Raman and XPS analysis. In the present study also, gas phase methane partial oxidation modeling and the synthesizing of mesoporous SBA-15 silica with different pore sizes were investigated. For the samples prepared by sol-gel method, XRD analysis showedthat cobalt exists in the form of Co3O4and Pb exist in the form of PbO. BET surface areas of the Co loaded catalysts are in the range of 479.5-640.1 m2/g. However, in Pb loaded samples, higher metal loading decrease the surface area up to 4.63 m2/g. Considering the both Co and Pb containing bi-metallic samples, TEM and BET results revealed that the ordered hexagonal mesostructure was fully destroyed. The samples prepared by incipient wetness impregnation and post grafting method characterized by using BET, TEM, Raman and XPS analysis. According to the BET results all the samples show ordered mesostructure in agreement with TEM results for all Co and/or SBA-15 mesoporous samples. TEM results also revealed that, the Co(5%) Pb(5%)-SBA-15 catalyst prepared by incipient wetness impregnation method possess big cobalt and lead oxide crystallines on the mesoporous structure. Raman analysis results indicated that cobalt exist in Co3O4 form. According to XPS results all samples containing cobalt include Co3O4. The partial oxidation of methane was carried out in a fixed bed flow-type reactor in a temperature range of 50&ndash / 850&deg / C under atmospheric pressure.According to the reaction test results, the 0.5%Rh-Co-SBA15 catalyst shows the highest methane conversion (82%) and H2 selectivity. The non-precious metal show lower reactivities, addition of Pb to the Co-SBA-15 catalyst increases the catalytic activity and decrease the H2 production temperature.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-20T21:00:39Z No. of bitstreams: 1 AlexsandraRodriguesDoNascimento_TESE.pdf: 3128857 bytes, checksum: db683b893d3db23b5af91852c4aed0e3 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-01-21T20:23:04Z (GMT) No. of bitstreams: 1 AlexsandraRodriguesDoNascimento_TESE.pdf: 3128857 bytes, checksum: db683b893d3db23b5af91852c4aed0e3 (MD5) / Made available in DSpace on 2016-01-21T20:23:04Z (GMT). No. of bitstreams: 1 AlexsandraRodriguesDoNascimento_TESE.pdf: 3128857 bytes, checksum: db683b893d3db23b5af91852c4aed0e3 (MD5) Previous issue date: 2014-09-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Diversos materiais est?o atualmente em estudo para o processo de captura de CO2, a exemplo dos ?xidos met?licos e ?xidos met?licos mistos, ze?litas, materiais carbon?ceos, estruturas metal-org?nicas (MOF?s), organos?lica e superf?cies de s?lica modificadas. Neste trabalho, analisou-se a capacidade de adsor??o de CO2 em materiais mesoporosos de diferentes estruturas, como o MCM-48 e SBA-15, sem impregna??o e impregnados com n?quel nas propor??es 5 %, 10 % e 20 % (m/m), denominados como 5Ni-MCM-48, 10NiMCM-48, 20Ni-MCM-48 e 5Ni-SBA-15, 10Ni-SBA-15, 20Ni-SBA-15. Os materiais foram caracterizados atrav?s das an?lises de difra??o de raios X (DRX), an?lise t?rmica (TG e DTG), espectroscopia na regi?o do infravermelho com transformada de Fourier (FT-IR), adsor??o e dessor??o de N2 (BET) e microscopia eletr?nica de varredura (MEV) com EDS. O processo de adsor??o foi realizado variando-se a press?o de 100 - 4000 kPa e mantendo-se a temperatura constante e igual a 298 K. Na press?o de 100 kPa, as maiores concentra??es de adsor??o ocorreram para os materiais 5Ni-MCM-48 (0,795 mmol g-1 ) e SBA-15 (0,914 mmol g -1 ) n?o impregnado, e, na press?o de 4000 kPa, para os materiais MCM-48 (14,89 mmol g-1 ) e SBA-15 (9,97 mmol g-1 ) n?o impregnados. Os resultados mostraram que a capacidade de adsor??o varia positivamente com a ?rea espec?fica, no entanto, apresenta uma depend?ncia direta com o tipo e geometria dos canais da estrutura porosa. Os dados obtidos foram ajustados atrav?s dos modelos de Langmuir e Freundlich e os par?metros termodin?micos avaliados foram energia livre de Gibbs e entropia do sistema de adsor??o / Several materials are currently under study for the CO2 capture process, like the metal oxides and mixed metal oxides, zeolites, carbonaceous materials, metal-organic frameworks (MOF's) organosilica and modified silica surfaces. In this work, evaluated the adsorption capacity of CO2 in mesoporous materials of different structures, such as MCM-48 and SBA- 15 without impregnating and impregnated with nickel in the proportions 5 %, 10 % and 20 % (m/m), known as 5Ni-MCM-48, 10Ni-MCM-48, 20Ni-MCM-48 and 5Ni-SBA-15, 10NiSBA-15, 20Ni-SBA-15. The materials were characterized by means of X-ray diffraction (XRD), thermal analysis (TG and DTG), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption and desorption (BET) and scanning electron microscopy (SEM) with EDS. The adsorption process was performed varying the pressure of 100 - 4000 kPa and keeping the temperature constant and equal to 298 K. At a pressure of 100 kPa, higher concentrations of adsorption occurred for the materials 5Ni-MCM-48 (0.795 mmol g-1 ) and SBA-15 (0.914 mmol g-1 ) is not impregnated, and at a pressure of 4000 kPa for MCM-48 materials (14.89 mmol g-1) and SBA-15 (9.97 mmol g-1) not impregnated. The results showed that the adsorption capacity varies positively with the specific area, however, has a direct dependency on the type and geometry of the porous structure of channels. The data were fitted using the Langmuir and Freundlich models and were evaluated thermodynamic parameters Gibbs free energy and entropy of the adsorption system

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T22:35:16Z No. of bitstreams: 1 DanielleDeOliveiraMaia_TESE.pdf: 2480138 bytes, checksum: 11e89b7c4d42403108c704fd453975d5 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T20:04:06Z (GMT) No. of bitstreams: 1 DanielleDeOliveiraMaia_TESE.pdf: 2480138 bytes, checksum: 11e89b7c4d42403108c704fd453975d5 (MD5) / Made available in DSpace on 2016-06-01T20:04:06Z (GMT). No. of bitstreams: 1 DanielleDeOliveiraMaia_TESE.pdf: 2480138 bytes, checksum: 11e89b7c4d42403108c704fd453975d5 (MD5) Previous issue date: 2015-07-23 / SBA-15 s?o materiais mesoporosos, que possuem uma rede de canais e poros de tamanho bem definido na escala nanom?trica, al?m de outras caracter?sticas, tais como, elevada estabilidade t?rmica e ?rea superficial. Essa arquitetura particular de poros torna esses materiais promissores na ?rea de ancoramento de uma variedade de compostos na matriz da s?lica resultando em aplica??es nas diversas ?reas, dentre elas, na cat?lise. Nesse trabalho, foram sintetizados complexos de Base de Schiff com n?quel (II) para serem ancorados na SBA-15 funcionalizada com 3-cloropropiltrimet?xisilano realizando um estudo da estabilidade t?rmica desses compostos. Ap?s a s?ntese dos complexos, estes foram caracterizados por an?lise elementar (CHN), ponto de fus?o, condutividade, susceptibilidade magn?tica, espectroscopia de absor??o na regi?o do UV-vis?vel, espectroscopia de absor??o na regi?o do infravermelho e an?lises t?rmicas (TG/DTG). A an?lise elementar sugere que os complexos apresentam as seguintes f?rmulas qu?micas gerais: [Ni(C18H19N3O2)].2CH3COO.H2O, [Ni(C20H23N3O2)(2Cl)].2H2O, [Ni(C19H20N3O2)(2Cl)].3H2O, sendo L1= C18H19N3O2, L2= C20H23N3O2, L3 = C19H20N3O2. Na espectroscopia de absor??o na regi?o do UV - vis?vel e infravermelho dos complexos foi evidenciada a coordena??o metal - ligante. Ap?s caracteriza??o dos complexos, estes foram ancorados no material mesoporoso. A caracteriza??o desses materiais foi realizada por difra??o de raios - X, fluoresc?ncia de raios - X, adsor??o e dessor??o de N2, espectroscopia de absor??o na regi?o do infravermelho e an?lises t?rmicas (TG/DTG). No DRX foram observados tr?s picos principais de difra??o, cujos ?ndices de Miller s?o (100), (110) e (200), mostrando que mesmo ap?s a ancoragem, os materiais mesoporosos n?o perderam suas caracter?sticas estruturais. As porcentagens dos elementos (n?quel, cloro e s?lica) encontrados nos materiais atrav?s da an?lise de fluoresc?ncia de raios - x mostraram que os complexos foram ancorados nos poros da s?lica. Atrav?s da adsor??o e dessor??o de N2, foram observadas que os materiais apresentaram isoterma do tipo IV e histerese do tipo H1 caracter?sticos dos materiais mesoporos. Na espectroscopia de absor??o na regi?o do infravermelho, os materiais ancorados apresentaram bandas caracter?sticas dos ligantes (Base de Schiff) e da s?lica evidenciando o sucesso da ancoragem. Na an?lise t?rmica, foram observadas a decomposi??o de ?gua adsorvida, ?gua coordenada, aminas, arom?ticos, ligantes, cloropropiltrimet?xisilano e o aumento na estabilidade t?rmica das s?licas ancoradas com complexos comparado ao complexo livre. / SBA-15 are mesoporous materials, having a network of channels and well defined pore size in the nanometer range, as well as, other features such as high thermal stability and surface area. This particular pore architecture makes these promising materials in the anchoring area of a variety of compounds in the silica matrix resulting in applications in various fields, among them, in catalysis. In this work, complexes were synthesized Schiff base with nickel (II) to be anchored in the functionalized SBA-15 3 ? chloropropyltrimethoxysilane and a study of the thermal stability of these compounds. After synthesis of the complexes, they were characterized by elemental analysis (CHN), melting point, conductivity, magnetic susceptibility, absorption spectroscopy in the UV-visible region absorption, spectroscopy in the infrared region and thermal analysis (TG/DTG). Elemental analysis suggests that the complexes have the general formula chemical: [Ni(C18H19N3O2)].2CH3COO.H2O, [Ni(C20H23N3O2)(2Cl)].2H2O, [Ni(C19H20N3O2)(2Cl)].3H2O, and L1= C18H19N3O2, L2= C20H23N3O2, L3 = C19H20N3O2. In absorption spectroscopy in UV - visible and infrared complexes was evidenced the coordination metal - ligand. After characterization of the complexes, confirming the metal - ligand coordination, they have been anchored in the mesoporous material. The characterization of these materials were made by x- ray diffraction, x- ray fluorescence, N2 adsorption and desorption spectroscopy, the infrared spectroscopy and thermal analysis (TG/DTG). XRD analysis revealed three main diffraction peaks, whose Miller indices are (100), (110) and (200), showing that even after the anchoring, the mesoporous materials do not lose their structural characteristics. The percentages of the elements (nickel chloride and silica) found in the anchored materials through the x-ray fluorescence analysis showed that the complexes were anchored in the pores of the silica. Through adsorption and desorption of N2, we observed that the materials presented isotherm type IV and type H1 hysteresis characteristic of mesoporous materials. In the infrared spectroscopy, the materials showed characteristic bands of ligands (Schiff base) and silica demonstrating the success of the anchor. In the thermal analysis (TG/DTG), there were observed the decomposition of adsorbed water, coordinated water, amines, aromatics, ligands, chloropropyltrimethoxysilane and an increase in thermal stability (removal of ligand) of silicas anchored [Ni(L1)]SBA-15, [Ni(L2)SBA-15 and [Ni(L3)SBA-15 compared of free complexes, showing successful anchoring of complex molecular sieve.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T22:35:16Z No. of bitstreams: 1 JoaoPauloDaCostaEvangelista_TESE.pdf: 3170006 bytes, checksum: b1459f824b08153ad43dfbda6bced227 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T20:54:29Z (GMT) No. of bitstreams: 1 JoaoPauloDaCostaEvangelista_TESE.pdf: 3170006 bytes, checksum: b1459f824b08153ad43dfbda6bced227 (MD5) / Made available in DSpace on 2016-06-01T20:54:29Z (GMT). No. of bitstreams: 1 JoaoPauloDaCostaEvangelista_TESE.pdf: 3170006 bytes, checksum: b1459f824b08153ad43dfbda6bced227 (MD5) Previous issue date: 2015-07-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Esse estudo prop?s-se a obter biodiesel a partir da esterifica??o do ?cido oleico com os catalisadores Zr-SBA-15, Nb-SBA-15, SO42-/Zr-SBA-15 e SO42-/Nb-SBA-15 obtidos pela inser??o de Zr e Nb no suporte SBA-15 e sulfata??o do suporte impregnado. O suporte SBA-15 foi sintetizado pelo m?todo hidrot?rmico. O catalisador foi incialmente sintetizado pelo m?todo de impregna??o via ?mida, adicionando 4,2 mL de uma solu??o ? 30 % do percursor do metal (Zr e Nb) em cada grama da SBA-15. Ap?s a impregna??o foi realizado o processo de sulfata??o. As condi??es reacionais da s?ntese do biodiesel utilizadas nesse estudo foram: quantidade de catalisador (5% em massa), raz?o molar de metanol:?cido oleico (20:1), tempo reacional (8 h) e temperatura de refluxo (65?C). Os catalisadores foram analisados por: difra??o de raios-X (DRX), an?lise termogravim?trica (TG/DTG), espectroscopia de infravermelho por transformada de Fourier (FTIR), adsor??o/dessor??o de nitrog?nio, microscopia eletr?nica de varredura (MEV), espectroscopia de energia dispersiva (EDS) e teste de acidez para identifica??o da estrutura, composi??o e verifica??o da presen?a de s?tios ?cidos. Os resultados de caracteriza??o indicaram que o suporte SBA-15 preservou a estrutura hexagonal ordenada, ap?s a incorpora??o de Zr e Nb. Observou-se a presen?a de nanopart?culas desses metais dispersas na superf?cie e no interior dos canais microporosos e mesoporosos dos catalisadores Zr-SBA-15 e Nb-SBA-15. Ap?s a sulfata??o, aumentou a quantidade de s?tios ?cidos e a estrutura ordenada foi mantida. Para os catalisadores Zr-SBA-15 e SO42-/Zr-SBA-15 houve a forma??o das estruturas tetragonal e monocl?nica do ZrO2, j? para os demais catalisadores Nb-SBA-15 e SO42-/Nb-SBA-15 formaram-se estruturas amorfas. A atividade catal?tica foi avaliada pela rea??o de esterifica??o do ?cido oleico via rota et?lica, utilizando todos os catalisadores sintetizados. O biodiesel obtido com SO42-/Zr-SBA-15 apresentou propriedades f?sico-qu?micas dentro das normas especificadas pela resolu??o N?7/2008 da ANP e melhor rendimento com 80,7%. Foi verificado que os catalisadores sulfatados, produziram maior rendimento com rela??o aos n?o sulfatados. O suporte SBA-15 n?o apresentou atividade catal?tica. / Fatty acids such as oleic acid, have received particular attention as raw material, due to its abundance, availability and relatively high purity, being considered as potential materials for production of biodiesel. The esterification reaction of oleic acid using heterogeneous catalysts can be a promising alternative for biodiesel production. This study proposes to find a biodiesel through esterification of oleic acid with Zr-SBA-15, Nb-SBA-15, SO42?/Zr-SBA-15 and SO4 2?/Nb-SBA-15 catalysts, obtained by insertion of Zr and Nb in support SBA-15 and sulfation of the impregnated support. SBA-15 support was synthesized by hydrothermal method. Support SBA-15 was synthesized by hydrothermal method. The catalyst was initially synthesized by the wet impregnation method, followed by sulfation process. The catalysts were analyzed: X-ray diffraction (XRD), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption/desorption, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and acidity test to identify the structure, composition and verification the presence acid sites. The characterization results indicated that the SBA-15 support preserved the ordered hexagonal structure after the incorporation of Zr and Nb. It was observed the presence of nanoparticles these metal dispersed on the surface and within the microporous and mesoporous channels of Zr-SBA-15 and Nb-SBA-15 catalysts. After sulfation, increased amount of acid sites and the ordered structure was maintained. For Zr-SBA-15 and SO4 2?/Zr-SBA-15 catalyst was the formation of tetragonal and monoclinic structures of ZrO2, as for the other, Nb-SBA-15 and SO42?/Nb-SBA-15 catalyst were formed amorphous structures. The catalytic activity was evaluated by the esterification reaction of oleic acid via ethyl route, using all the synthesized catalysts. Biodiesel obtained with SO42?/Zr-SBA-15 presented physicochemical properties within the standards specified by the Resolution N? 45/2014 ANP and obtained the best yield with 80.7%. It was found that sulfated catalysts, produced higher yields with respect to nonsulfated. The SBA-15 support showed no catalytic activity.

Uma das desvantagens dos bio-óleos precursores do biodiesel é a alta carga de compostos oxigenados que diminuem seu poder de combustão, reduzindo sua eficiência e inviabilizando seu uso em larga escala. Nesse contexto, o processo de hidrodesoxigenação (HDO) é relevante, dado que elimina esses compostos através de uma reação catalítica e, portanto, aumenta o poder calorífico do combustível. Neste trabalho, estudou-se a HDO do guaiacol (2-metoxifenol) como composto modelo dos bio-óleos derivados da biomassa e avaliou-se o desempenho de catalisadores de Ni e Mo no processo. Estudou-se a performance de um catalisador suportado em SBA-15 - um material mesoporoso de sílica de alta área superficial - em comparação a de um catalisador tradicional suportado em gama-alumina. Para tal, utilizou-se um sistema contínuo em fase gasosa e reator de leito fixo. Utilizaram-se técnicas de caracterização de catalisadores, como adsorção de N2, MEV, MET, DRX, TPR-H2, FTIR, TPO-O2, Raman e TGA. Através das análises DRX e MET, comprovou-se que se formaram partículas de NiO e MoO3 de menor tamanho e mais dispersas no caso do catalisador de SBA-15, devido à menor interação com o suporte e maior área superficial, o que resultou em um grau de redução de 91,6 % deste catalisador, em comparação a 73,4 % do outro, analisados por TPR-H2. Os testes catalíticos mostraram que o catalisador de NiMo/SBA-15 supera o de alumina em termos de conversão no intervalo de 200 a 300 °C, com ciclohexeno e ciclohexano como principais produtos, em face à maior seletividade a catecol e fenol no NiMo/?-Al2O3. A 300 °C, o catalisador suportado em sílica alcançou taxas de 66,5 % para a HDO e 35,3 % HDA (hidrodesaromatização), enquanto o de alumina obteve somente 30,8 e 2,7 %, respectivamente. Finalmente, comprovou-se que o SBA-15 teve uma taxa de desativação por coque de 1,14 mgcoque gcat-1 h-1, 31 % menor que a taxa do catalisador de alumina, cujos depósitos foram de carbono grafítico bem estruturado e irreversível. Em vista dos resultados obtidos, esta dissertação apresenta as rotas e mecanismos de reação do guaiacol nos catalisadores estudados, conhecimento que é relevante para o desenvolvimento e aprimoramento de futuros catalisadores da HDO. / A key disadvantage of the bio-oils precursors of biodiesel is the high load of oxygenated compounds that reduce their heat of combustion, dropping their efficiency and making them unfeasible on a large scale. In light of that, the hydrodeoxygenation process (HDO) is relevant, since it eliminates these compounds through a catalytic reaction, thus increasing the calorific value of the fuel. In this work, the HDO of guaiacol (2-methoxyphenol) as a model compound of the bio-oils derived from biomass was studied and the performance of Ni-Mo catalysts was evaluated. A catalyst supported on SBA-15 - a high surface area mesoporous silica material - was compared to a traditional gamma-alumina-supported catalyst. For this purpose, a continuous gas phase setup with fixed bed reactor was employed. The catalysts properties were identified by N2 adsorption, SEM, TEM, XRD, H2-TPR, FTIR, O2-TPO, Raman and TGA techniques. Through XRD and TEM, it was verified that smaller and more dispersed NiO and MoO3 particles were formed in the case of the SBA-15 catalyst, due to the lower interaction with the support and the greater surface area, which resulted in a degree of reduction of 91.6% for this catalyst, as opposed to 73.4% for the other one, both analyzed by H2-TPR. The catalytic tests showed that the NiMo/SBA-15 outperforms the alumina catalyst in terms of conversion in the range of 200 to 300 °C, with cyclohexene and cyclohexane as main products, in contrast with major selectivity to catechol and phenol on NiMo/?-Al2O3. At 300 °C, the silica-supported catalyst achieved rates of 66.5% for HDO and 35.3% for HDA (hydrodearomatization), whereas alumina reached only 30.8 and 2.7%, respectively. Finally, it was shown that the SBA-15 catalyst had a coke deactivation rate of 1.14 mgcoke gcat-1 h-1, 31% lower than the alumina catalyst, whose coke deposits consisted of well-structured irreversible graphitic carbon. In view of the results, this dissertation proposes the routes and reaction mechanisms of guaiacol on the studied catalysts, knowledge that is pertinent for the development and improvement of future HDO catalysts.

This thesis deals with the study of several catalysts for the Fischer-Tropsch synthesis in the Biomass-To-Liquid process. In this work two groups of catalysts were tested. On the one hand, two series of catalysts with cobalt loadings of 6 and 12 wt% over SiO2 and some of them containing 5wt% of TiO2 were tested. One the other hand, other two series of mesoporous short channel SBA-15, all of them with cobalt loadings of 12wt% and some with 5wt% of titania. The first series was supported on SBA-15 DeWitte and the second one on SBA-15 Martinez. On the one hand, the influence of water addition to the feed, titania content and cobalt loading to the catalyst and was studied, as well as the consequences of a GHSV. The FT reaction was carried out along 5 periods of 24 hours each, in which conditions such as feed and water content were modified, enabling the study of these parameters. It was found that water provokes an increase of the CO conversion and has a positive kinetic effect on the rate to hydrocarbons. However, this fact reaction is followed by a quick deactivation, enhanced by high water partial pressures. Most of that deactivation is irreversible since it is not completely recovered after water removal. On the other hand, differences between the supports were studied. Some SBA-15 supported catalysts show CO diffusion limitations at longer channel lengths than what applies for conventional 3D porous supports. Titania grafting increases the rate to hydrocarbons, showing positive results for FT catalysts development.

Over the past decades, there have been worldwide efforts to synthesize new types of ordered porous materials for catalysis, separations, etc. Among those, mesoporous material with microporous walls are promising in a sense that while mesopores act as channels for the reactant transport with little diffusion limitation, micropores in the wall act as active sites for reactions or storage of the molecules. In this study, we focused on the SBA-15 material, which is a highly ordered mesoporous silica material with micropores present in the wall. We have studied the synthesis of the material by manipulating various factors that are known to have influence on the porous characteristic of the material. We have aimed our studies particularly on the micropores present in the material. Unlike zeolite materials, which have regular, well characterized pore structures, micropores in the SBA-15 are not ordered, thus may have a very broad pore size distribution. We have synthesized sets of mesoporous silica materials that have characteristics similar to those reported in the literature. Using microwave heating, we were able to synthesize the target material within a short period of time, about 10 to 12-fold reduction of the conventionally known synthesis time. The synthesized materials were initially characterized using XRD and SEM. Adsorption studies were then undertaken on the materials to determine the surface area and pore structure. The interpretation of micropores has heretofore been problematic and the models are ambiguous. Relatively simply ordered, 1-dimensional channel type, zeolite materials were also studied; MTW, MTT, TON, ATS, VET frameworks. Adsorption isotherms of these materials were obtained and simple empirical models were developed to determine the pore size distribution. Further, a sequential adsorption technique, using n-nonane as a preadsorbate, was used to evaluate the realistic external surface areas of zeolite materials and mesopore surface areas of micro-mesoporous materials. Applying this technique to “multidimensional pore system” will provide another way to obtain the realistic surface area and mesopore size distribution.

No description available.