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No. of bitstreams: 1 florencepereiranovaisantunes.pdf: 6342982 bytes, checksum: b846018e0b6dd62bd5ea051a6710659a (MD5) Previous issue date: 2015-06-03 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Associada à redução das emissões veiculares, o principal processo de interesse no hidrotratamento é a hidrodessulfurização, HDS, na qual o átomo de enxofre presente nas moléculas organosulfuradas é adsorvido no catalisador e reage com hidrogênio, formando sulfeto de hidrogênio (H2S) e os hidrocarbonetos livres de heteroátomos. As reações de HDS são exotérmicas e irreversíveis, sendo que seu mecanismo envolve reações de hidrogenólise – quebra da ligação CS – e de hidrogenação – saturação das duplas ligações. Existem divergências na literatura sobre o mecanismo dessas reações. O interesse pela área de materiais relacionados às reações deste tipo e à catálise heterogênea está em constante expansão devido à possibilidade de produzir diversos tipos de materiais de grande aplicabilidade e custos menos onerosos. Os estudos sobre HDS buscam o desenvolvimento de catalisadores com maior capacidade para promover uma remoção mais efetiva do enxofre, além de esclarecimentos referentes ao seu mecanismo. Os catalisadores mais comumente usados são compostos que possuem estruturas de MoS2 como fase ativa. Apesar de possuir atividade catalítica na forma mássica, o MoS2 geralmente é suportado em uma superfície com extensa área como suporte, geralmente óxidos, sendo a γalumina a mais utilizada. Existem diversos estudos recentes reportando uso de outros tipos de óxidos, como TiO2, sílica, zeólitas, ZrO2, MgO e óxidos mistos. No presente trabalho, é feita a proposta de dois tipos de estruturas de catalisadores de sulfeto de molibdênio suportados em MgO, através de cálculos ab initio. É de aceitação geral, hoje em dia, que a atividade dos catalisadores de HDS está fundamentalmente ligada à existência de vacâncias aniônicas de enxofre, situadas, predominantemente, nas bordas dos cristalitos da fase ativa, já que o enxofre dos planos basais está muito fortemente ligado para permitir a formação destas vacâncias. Levandose em conta que a formação de vacâncias é uma etapa crucial para HDS, procuramos obter informações estruturais mais precisas que auxiliem no entendimento dessa etapa da reação. Para isso mostramos o estudo da formação de sítios coordenativamente insaturados na borda do sulfeto de molibdênio suportado em MgO. Além disso, discutimos a interação do sulfeto com o suporte, variando o número de camadas de sulfeto e a presença de átomo promotor de cobalto na borda. Com isso, procuramos fornecer informações estruturais de modelos teóricos de MoS2 suportado em MgO utilizando DFT a fim de contribuir com estudos nesse contexto. Para isso, foi calculada a energia de formação de vacâncias, diferença da densidade de cargas eletrônicas, pDOS e análise das cargas de Bader. Concluímos que tanto o suporte quanto o átomo promotor influenciam na formação de vacâncias na borda do sulfeto de molibdênio suportado em MgO. A influência dessas variáveis está em dependência com o tamanho da lamela, proporções de átomos de enxofre de borda e tipo de interação do sulfeto com o suporte. Em geral podemos afirmar que os dois agem de modo a diminuir a energia de formação de vacâncias, contribuindo para a melhora dessa etapa. / With respect to the reduction of pollutant emission of vehicles, the main process of hydrotreatment is the hydrodesulfurization, HDS, in which the sulfur atom of the organosulfur molecules is adsorved on the catalyst and reacts with hydrogen forming hydrogen sulfide (H2S) and heteroatomfree hydrocarbons. The HDS reactions are exothermic and irreversible and their mechanisms involve hydrogenolysis reactions – the break of CS bond – and the hydrogenation – saturation of double bonds. There are many divergences in the literature about the mechanism of these reactions. The interest about these types of reactions and the heterogenous catalysis in the material field is in constant expansion due to the possibility of producing several types of materials with great applicabilities and inferior costs. The studies about HDS seek the development of catalysts with a higher capacity to promote a more effective removal of sulfur besides the elucidation of their mechanisms. The catalysts more commonly used are compounds which possess MoS2 structures as the active phase. Even though it has catalytic activity in the bulk structure, the MoS2 is generally supported on a surface with an extended area, usually oxides such as alumina, which is the most utilized. There are many recent studies γ reporting the use of other types of oxides such as TiO2, silica, zeolites, ZrO2, MgO and mixed oxides. In this present work, a proposition of two types of catalyst structures of molybdenum sulfides supported on MgO is done by means of ab initio calculations. It is commonly accepted nowadays that the activity of HDS catalysts is greatly related to the existence of anionic vacancies of sulfur located majorly on the edges of the active phase, since the sulfurs of the basal planes are strongly bonded to permit the formation of these vacancies. Taking into account that the vacancy formation is a crucial step for HDS, we sought to obtain more precise structural information to assist the understanding of this reaction step. Thereby, we presented the study of the formation of the coordenative unsaturated sites on the edge of the molybdenum sulfide supported on MgO. Moreover, we discussed about the interaction between the sulfide and the support by varying the amount of the sulfide layers and the presence of the cobalt atom on the edge. Thereby, we sought to provide structural information on the theoretical models of MoS2 supported on MgO using DFT in order to contribute with studies in this context. In order to do that, we calculated the energy of the vacancy formation, the difference of the charge densities, pDOS and Bader charge analysis. We concluded that the support and the promoting atoms influence the formation of the vacancies on the edge of the molybdenum supported on MgO. The influence of these variables depends on the size of the layer, the proportions of the sulfur atoms on the edge and the type of the interaction of the sulfide on the support. In short, we can confirm that both act to decrease the energy of the vacancy formation, thus contributing to the improvement of this step.

This master thesis investigates linkage between personality characteristics and digital records on the Internet. The theoretical part is focused on selected theories of personality traits, brief description of social networks and on current studies connected with relationship between digital records and personality characteristics. Empirical research is dedicated to test interdependences between user profiles at the LinkedIn and Hogan's MVPI and HDS using the research sample (N=238, after reduction N=129 due to limited number of LinkedIn users). Based on LinkedIn data which were reduced to 6 new variables, results describe statistically significant models predicting scores for some scales of MVPI and HDS. However, maximum adjusted R2 was only 15,5% for the best regression model which was predicting Altruistic scale (MVPI).

The pore diameter of a catalyst support controls the diffusion of reactant molecules to the catalytic active sites; thus, affecting the rates and conversions of the hydrotreating reactions. Desirable textural properties of SBA-15 makes it a potential alternative to the conventionally used γ-Al2O3 support due to the fact that its pore size can be manipulated via controlling the synthesis parameters, while maintaining relatively high surface area. Larger pore diameter SBA-15 supports may facilitate the diffusion of bulky molecules as that of the asphaltenes present in the heavy petroleum fractions, making it a potential catalyst support for hydrotreating operations. Considering the very sour nature of Canadas bitumen with high sulfur contents in the range of 2-6 wt %, the appreciably high sulfur contents particularly present in Athabasca derived heavy gas oils (about 4 wt % sulfur), the rising demand for cleaner fuels, and also the increasing stringency on environmental standards, the need for novel and improved hydrotreating catalysts cannot be overemphasized. By varying the molar ratio of hexane to ammonium fluoride, the pore channels of SBA-15 could be varied. Controlling the pore diameter of these supports via micelle swelling facilitated the production of larger pore diameter SBA-15-supported catalysts. In this project, four mesoporous silica SBA-15 catalyst supports with pore diameters in the range of 5-20 nm were synthesized in the preliminary phase using hexane as the micelle swelling agent and subsequently utilized for the loading of 2 wt.% Fe and 15 wt.% W catalyst metals, respectively. The hexagonal mesoscopic structure of these materials were characterized using powder small-angle X-ray scattering (SAXS), N2 adsorption-desorption isotherms, TEM and SEM images. Powder XRD analysis evidenced inhomogeneous metal dispersion on the largest pore diameter catalyst. An optimum pore diameter of 10 nm was found for Cat-B and subsequently used to obtain the optimum Fe and W loadings required to achieve the best hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities. The optimum catalyst was found to be Cat-H with metal loadings of 3 wt.% Fe and 30 wt.% W. At these loadings and temperatures of 375°C, 388°C, and 400°C, HDS activities of 53.4%, 64.1%, and 73.3% with corresponding HDN activities of 21.9%, 26.2%, and 38.3%, respectively, were recorded. Catalytic performance evaluations conducted on equal mass loading using a reference commercial γ-Al2O3-supported FeW catalyst offered HDS activities of 69.3%, 80.4%, and 89.1%, with corresponding HDN activities of 16.4%, 32.4%, and 49.3% at the same temperatures studied. However, no significant changes in HDS and HDN activities were observed for similar evaluations on volume percent metals loading basis. Kinetic studies performed with the optimum FeW/SBA-15 catalyst suggested activation energies of 147.2 and 150.6 kJ/mol for HDS and HDN, respectively, by the Langmuir-Hinshelwoods model. Similar results were predicted by the Power Law and Multi-parameter models for HDS (129.6 and 126.7 kJ/mol, respectively), which does not conclusively make the latter model clearly stand out as the best. Data fitting by the Power Law suggested reaction orders of 2 and 1.5 for HDS and HDN, which seem to be consistent for the hydrotreatment of heavy gas oil. Finally, a long-term deactivation study spanning a period of 60 days time-on-stream showed the optimum catalyst to be stable under hydrotreating experiments conducted in a downward flow micro-trickle bed reactor at temperature, pressure, liquid hourly space velocity (LHSV), and gas/oil ratio of 375400˚C, 8.8 MPa, 1h-1, and 600 mL/mL (at STP), respectively.

The production of clean fuel faces the challenges of high production cost and complying with stricter environmental regulations. In this research, the ability of using a novel technology of upgrading heavy oil to treat Light Gas Oil (LGO) will be investigated. The target of this project is to produce cleaner transportation fuel with much lower cost of production. Recently, a novel process for upgrading of heavy oil has been developed at University of Waterloo. It is combining the two essential processes in bitumen upgrading; emulsion breaking and hydroprocessing into one process. The water in the emulsion is used to generate in situ hydrogen from the Water Gas Shift Reaction (WGSR). This hydrogen can be used for the hydrogenation and hydrotreating reaction which includes sulfur removal instead of the expensive molecular hydrogen. This process can be carried out for the upgrading of the bitumen emulsion which would improve its quality. In this study, the hydrodesulphurization (HDS) of LGO was conducted using in situ hydrogen produced via the Water Gas Shift Reaction (WGSR). The main objective of this experimental study is to evaluate the possibility of producing clean LGO over dispersed molybdenum sulphide catalyst and to evaluate the effect of different promoters and syn-gas on the activity of the dispersed Mo catalyst. Experiments were carried out in a 300 ml Autoclave batch reactor under 600 psi (initially) at 391oC for 1 to 3 hours and different amounts of water. After the hydrotreating reaction, the gas samples were collected and the conversion of carbon monoxide to hydrogen via WGSR was determined using a refinery gas analyzer. The sulphur content in liquid sample was analyzed via X-Ray Fluorescence. Experimental results showed that using more water will enhance WGSR but at the same time inhibits the HDS reaction. It was also shown that the amount of sulfur removed depends on the reaction time. The plan is to investigate the effect of synthesis gas (syngas) molar ratio by varying CO to H2 ratio. It is also planned to use different catalysts promoters and compare them with the un-promoted Mo based catalysts to achieve the optimum reaction conditions for treating LGO. The results of this study showed that Ni and Co have a promoting effect over un-promoted Mo catalysts for both HDS and WGSR. Ni was found to be the best promoter for both reactions. Fe showed no significant effect for both WGSR and HDS. V and K have a good promoting effect in WGSR but they inhibited the HDS reaction. Potassium was found to be the strongest inhibitor for the HDS reaction since no sulfur was removed during the reaction

The production of clean fuel faces the challenges of high production cost and complying with stricter environmental regulations. In this research, the ability of using a novel technology of upgrading heavy oil to treat Light Gas Oil (LGO) will be investigated. The target of this project is to produce cleaner transportation fuel with much lower cost of production. Recently, a novel process for upgrading of heavy oil has been developed at University of Waterloo. It is combining the two essential processes in bitumen upgrading; emulsion breaking and hydroprocessing into one process. The water in the emulsion is used to generate in situ hydrogen from the Water Gas Shift Reaction (WGSR). This hydrogen can be used for the hydrogenation and hydrotreating reaction which includes sulfur removal instead of the expensive molecular hydrogen. This process can be carried out for the upgrading of the bitumen emulsion which would improve its quality. In this study, the hydrodesulphurization (HDS) of LGO was conducted using in situ hydrogen produced via the Water Gas Shift Reaction (WGSR). The main objective of this experimental study is to evaluate the possibility of producing clean LGO over dispersed molybdenum sulphide catalyst and to evaluate the effect of different promoters and syn-gas on the activity of the dispersed Mo catalyst. Experiments were carried out in a 300 ml Autoclave batch reactor under 600 psi (initially) at 391oC for 1 to 3 hours and different amounts of water. After the hydrotreating reaction, the gas samples were collected and the conversion of carbon monoxide to hydrogen via WGSR was determined using a refinery gas analyzer. The sulphur content in liquid sample was analyzed via X-Ray Fluorescence. Experimental results showed that using more water will enhance WGSR but at the same time inhibits the HDS reaction. It was also shown that the amount of sulfur removed depends on the reaction time. The plan is to investigate the effect of synthesis gas (syngas) molar ratio by varying CO to H2 ratio. It is also planned to use different catalysts promoters and compare them with the un-promoted Mo based catalysts to achieve the optimum reaction conditions for treating LGO. The results of this study showed that Ni and Co have a promoting effect over un-promoted Mo catalysts for both HDS and WGSR. Ni was found to be the best promoter for both reactions. Fe showed no significant effect for both WGSR and HDS. V and K have a good promoting effect in WGSR but they inhibited the HDS reaction. Potassium was found to be the strongest inhibitor for the HDS reaction since no sulfur was removed during the reaction

The pore diameter of a catalyst support controls the diffusion of reactant molecules to the catalytic active sites; thus, affecting the rates and conversions of the hydrotreating reactions. Desirable textural properties of SBA-15 makes it a potential alternative to the conventionally used γ-Al2O3 support due to the fact that its pore size can be manipulated via controlling the synthesis parameters, while maintaining relatively high surface area. Larger pore diameter SBA-15 supports may facilitate the diffusion of bulky molecules as that of the asphaltenes present in the heavy petroleum fractions, making it a potential catalyst support for hydrotreating operations. Considering the very sour nature of Canadas bitumen with high sulfur contents in the range of 2-6 wt %, the appreciably high sulfur contents particularly present in Athabasca derived heavy gas oils (about 4 wt % sulfur), the rising demand for cleaner fuels, and also the increasing stringency on environmental standards, the need for novel and improved hydrotreating catalysts cannot be overemphasized. By varying the molar ratio of hexane to ammonium fluoride, the pore channels of SBA-15 could be varied. Controlling the pore diameter of these supports via micelle swelling facilitated the production of larger pore diameter SBA-15-supported catalysts. In this project, four mesoporous silica SBA-15 catalyst supports with pore diameters in the range of 5-20 nm were synthesized in the preliminary phase using hexane as the micelle swelling agent and subsequently utilized for the loading of 2 wt.% Fe and 15 wt.% W catalyst metals, respectively. The hexagonal mesoscopic structure of these materials were characterized using powder small-angle X-ray scattering (SAXS), N2 adsorption-desorption isotherms, TEM and SEM images. Powder XRD analysis evidenced inhomogeneous metal dispersion on the largest pore diameter catalyst. An optimum pore diameter of 10 nm was found for Cat-B and subsequently used to obtain the optimum Fe and W loadings required to achieve the best hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities. The optimum catalyst was found to be Cat-H with metal loadings of 3 wt.% Fe and 30 wt.% W. At these loadings and temperatures of 375°C, 388°C, and 400°C, HDS activities of 53.4%, 64.1%, and 73.3% with corresponding HDN activities of 21.9%, 26.2%, and 38.3%, respectively, were recorded. Catalytic performance evaluations conducted on equal mass loading using a reference commercial γ-Al2O3-supported FeW catalyst offered HDS activities of 69.3%, 80.4%, and 89.1%, with corresponding HDN activities of 16.4%, 32.4%, and 49.3% at the same temperatures studied. However, no significant changes in HDS and HDN activities were observed for similar evaluations on volume percent metals loading basis. Kinetic studies performed with the optimum FeW/SBA-15 catalyst suggested activation energies of 147.2 and 150.6 kJ/mol for HDS and HDN, respectively, by the Langmuir-Hinshelwoods model. Similar results were predicted by the Power Law and Multi-parameter models for HDS (129.6 and 126.7 kJ/mol, respectively), which does not conclusively make the latter model clearly stand out as the best. Data fitting by the Power Law suggested reaction orders of 2 and 1.5 for HDS and HDN, which seem to be consistent for the hydrotreatment of heavy gas oil. Finally, a long-term deactivation study spanning a period of 60 days time-on-stream showed the optimum catalyst to be stable under hydrotreating experiments conducted in a downward flow micro-trickle bed reactor at temperature, pressure, liquid hourly space velocity (LHSV), and gas/oil ratio of 375400˚C, 8.8 MPa, 1h-1, and 600 mL/mL (at STP), respectively.

Submitted by Nayara Passos (nayara.passos@ufpe.br) on 2015-03-11T18:35:40Z No. of bitstreams: 2 TESE Bruno Otavio Piedade Prado.pdf: 9246891 bytes, checksum: c2ec036981695fc08a08b2eea1294846 (MD5) license_rdf: 1370 bytes, checksum: bd343fdf8e4779e91782baad59c34539 (MD5) / Made available in DSpace on 2015-03-11T18:35:40Z (GMT). No. of bitstreams: 2 TESE Bruno Otavio Piedade Prado.pdf: 9246891 bytes, checksum: c2ec036981695fc08a08b2eea1294846 (MD5) license_rdf: 1370 bytes, checksum: bd343fdf8e4779e91782baad59c34539 (MD5) Previous issue date: 2014 / Com os grandes avanços recentes dos sistemas computacionais, houve a possibilidade de ascensão de dispositivos inovadores, como os modernos telefones celulares e tablets com telas sensíveis ao toque. Para gerenciar adequadamente estas diversas interfaces é necessário utilizar o software dependente do hardware (HdS), que é responsável pelo controle e acesso a estes dispositivos. Além deste complexo arranjo de componentes, para atender a crescente demanda por mais funcionalidades integradas, o paradigma de multiprocessamento vem sendo adotado para aumentar o desempenho das plataformas. Devido à lacuna de produtividade de sistemas, tanto a indústria como a academia têm pesquisado processos mais eficientes para construir e simular sistemas cada vez mais complexos. A premissa dos trabalhos do estado da arte está em trabalhar com modelos com alto nível de abstração e de precisão que permitam ao projetista avaliar rapidamente o sistema, sem ter que depender de lentos e complexos modelos baseados em ISS. Neste trabalho é definido um conjunto de construtores para modelagem de plataformas baseadas em processadores, com suporte para desenvolvimento de HdS e reusabilidade dos componentes, técnicas para estimativa estática de tempo simulado em ambiente nativo de simulação e suporte para plataformas multiprocessadas. Foram realizados experimentos com aplicações de entrada e saída intensiva, computação intensiva e multiprocessada, com ganho médio de desempenho da ordem de 1.000 vezes e precisão de estimativas com erro médio inferior a 3%, em comparação com uma plataforma de referência baseada em ISS.

New catalyst development for the hydrotreating process, employing functionalized mesoporous carbon (mC) support is studied. mC support was prepared by the volume templating of alkali modified SBA-15 using sucrose as the carbon source and then functionalized using nitric acid of various concentrations (upto 8M HNO3). A series of NiMo catalysts (12% Mo and 2.4% Ni) were prepared using these functionalized mC supports. The supports and catalysts were characterized by N2 physisorption, SAXS, XRD, FTIR, TGA, SEM, TEM, H2-TPR and HRTEM. SAXS results indicated mild reduction in ordered structure of mesoporous carbons after functionalization. N2 physisorption analysis indicated progressive reduction in surface area and pore volume with the increase in nitric acid concentration. Enhancement of surface functional groups and acidity after functionalization were observed through FTIR spectroscopy and Boehm titration. SEM images showed the retention of needle like morphology in all functionalized carbon supports. TEM images showed that the increase in nitric acid concentration causes excessive etching, resulting in the reduction of ordered structure of functionalized mesoporous carbons. Hydrotreating study of these NiMo/mC catalysts were carried out under industrial operating conditions in a laboratory scale trickle bed reactor using coker light gas oil derived from Athabasca bitumen as feedstock. NiMo catalyst supported on 6M acid treated mC (i.e. NiMo/mC-6M) showed the highest activity due to higher surface functional groups, higher acidity and better textural properties. The HDS and HDN activities of NiMo/mC-6M catalyst were higher than that of NiMo/ã-Al2O3 catalyst owing to lower support metal interaction (SMI), higher surface area and effective functionalization. Using the mC-6M support, NiMo catalysts with different metal loading (12 27% Mo, 2.4 to 5.4% Ni) were prepared and characterized. Hydrotreating activity study of these catalysts indicated that the catalyst with 22% Mo and 2.9% Ni loading was the optimum catalyst on 6M functionalized mC support. Higher metal loading (>22%Mo) led to excessive pore blockage and improper metal dispersion resulting in decreased activity. Kinetic study of the optimum catalyst was carried out by varying temperature (330°C to 370°C), gas-to-oil ratio (400 1000 Nm3/m3), LHSV (1.0 to 2.5 hr-1) and pressure (7.8 to 9.8 MPa) and the data was fitted by non-linear regression method using power law model. The calculated reaction orders and activation energies were 2.8, 1.5 and 189 KJ/mol, 98.9 KJ/mol for HDS and HDN, respectively. The results of HRTEM and H2-TPR indicated lower SMI in mC supported catalyst resulting in the generation of qualitatively Type-II like NiMoS phase on functionalized mC supports, which is considered to be very active for hydrotreating. The hydrotreating activity of the optimum catalyst was higher than that of commercial catalyst (supported on ã-Al2O3). Long term deactivation experiment carried out over a total period of 10 weeks confirmed the durability of NiMo/mC catalyst for the duration of operation. This study reveals the immense capability of functionalized mC supports to become the potential alternative catalyst support to conventional ã-Al2O3 for the hydrotreating of gas oil feedstocks.

New catalyst development for the hydrotreating process, employing functionalized mesoporous carbon (mC) support is studied. mC support was prepared by the volume templating of alkali modified SBA-15 using sucrose as the carbon source and then functionalized using nitric acid of various concentrations (upto 8M HNO3). A series of NiMo catalysts (12% Mo and 2.4% Ni) were prepared using these functionalized mC supports. The supports and catalysts were characterized by N2 physisorption, SAXS, XRD, FTIR, TGA, SEM, TEM, H2-TPR and HRTEM. SAXS results indicated mild reduction in ordered structure of mesoporous carbons after functionalization. N2 physisorption analysis indicated progressive reduction in surface area and pore volume with the increase in nitric acid concentration. Enhancement of surface functional groups and acidity after functionalization were observed through FTIR spectroscopy and Boehm titration. SEM images showed the retention of needle like morphology in all functionalized carbon supports. TEM images showed that the increase in nitric acid concentration causes excessive etching, resulting in the reduction of ordered structure of functionalized mesoporous carbons. Hydrotreating study of these NiMo/mC catalysts were carried out under industrial operating conditions in a laboratory scale trickle bed reactor using coker light gas oil derived from Athabasca bitumen as feedstock. NiMo catalyst supported on 6M acid treated mC (i.e. NiMo/mC-6M) showed the highest activity due to higher surface functional groups, higher acidity and better textural properties. The HDS and HDN activities of NiMo/mC-6M catalyst were higher than that of NiMo/ã-Al2O3 catalyst owing to lower support metal interaction (SMI), higher surface area and effective functionalization. Using the mC-6M support, NiMo catalysts with different metal loading (12 27% Mo, 2.4 to 5.4% Ni) were prepared and characterized. Hydrotreating activity study of these catalysts indicated that the catalyst with 22% Mo and 2.9% Ni loading was the optimum catalyst on 6M functionalized mC support. Higher metal loading (>22%Mo) led to excessive pore blockage and improper metal dispersion resulting in decreased activity. Kinetic study of the optimum catalyst was carried out by varying temperature (330°C to 370°C), gas-to-oil ratio (400 1000 Nm3/m3), LHSV (1.0 to 2.5 hr-1) and pressure (7.8 to 9.8 MPa) and the data was fitted by non-linear regression method using power law model. The calculated reaction orders and activation energies were 2.8, 1.5 and 189 KJ/mol, 98.9 KJ/mol for HDS and HDN, respectively. The results of HRTEM and H2-TPR indicated lower SMI in mC supported catalyst resulting in the generation of qualitatively Type-II like NiMoS phase on functionalized mC supports, which is considered to be very active for hydrotreating. The hydrotreating activity of the optimum catalyst was higher than that of commercial catalyst (supported on ã-Al2O3). Long term deactivation experiment carried out over a total period of 10 weeks confirmed the durability of NiMo/mC catalyst for the duration of operation. This study reveals the immense capability of functionalized mC supports to become the potential alternative catalyst support to conventional ã-Al2O3 for the hydrotreating of gas oil feedstocks.

Este trabalho teve como objetivo avaliar a eficiência de um sistema combinado de alagados construídos, localizado no Parque Ecológico do Tietê em São Paulo, na melhoria da qualidade das águas. A estação de estudo é composta por um canal de decantação, um canal de macrófitas flutuantes (Eicchornia crassipes, Pistia stratioides, Salvinia auriculata) e emergentes (Typha angustifolia) de fluxo superficial, e duas células paralelas de solos filtrantes de fluxo vertical descendente cultivados com arroz (Oryza sativa). As coletas de água foram realizadas mensalmente, na entrada e saída de cada etapa do sistema, no período de fevereiro, março, junho e julho de 2004 e de março a setembro de 2005. As variáveis físicas, químicas e biológicas da água foram medidas e taxas de eficiência de remoção parcial e total do sistema foram calculadas. A estação construída de alagados mostrou-se eficiente principalmente na remoção de sulfato (52%), turbidez (86%), 'DBO IND.5' (41 - 64%), fósforo total (51 – 68%), nitrogênio albuminóide (51,7%), nitrito (77,8%) e nitrogênio amoniacal (57 – 84%). Os canais de macrófitas apresentaram um alto desempenho de remoção média para maioria das variáveis analisadas no trabalho, contribuindo com a maior porção na taxa de remoção total do sistema. Durante o período de estudo, provavelmente devido à falta de manejo do sistema, observou-se a volta dos nutrientes assimilados pelas macrófitas para a coluna d`água (N, P, Fe) com a decomposição das plantas e condições de anaerobiose nos solos filtrantes. Esses fatores, juntamente com a presença dos animais do parque atraídos pelo arroz, contribuíram com o baixo desempenho do canal de macrófitas e dos solos filtrantes na remoção de cor, turbidez, ferro total e coliformes em alguns meses de coleta. Para a maioria das variáveis analisadas, a água tratada pelo sistema de alagados construídos alcançou os limites e padrões estabelecidos pela Resolução CONAMA 357/2005 para águas doces de classe 2 (BRASIL, 2005). Contudo, em função dos dados obtidos, não se pode enquadrar totalmente o efluente, embora seja esperado que com a estabilização do sistema e um manejo adequado, a água tratada consiga atingir as características exigidas e possa ser enquadrada em águas doces de classe 2. / The aim of this work was evaluate the efficiency of combined constructed wetlands, located in the Tiete Ecological Park in São Paulo, in water quality improvement. The station consists of a settling channel, one free-floating (Eichhornia crassipes, Salvinia auriculata, Pistia stratiotes) and rooted emergent macrophyte-based system (Typha angustifolia) with surface flow and two cells of vertical flow filter soils in parallel, planted with rice (Oryza sativa). The water samples were collected monthly at the inlet and outlet of each step of the system, in the period of February, March, June and July of 2004 and of March to September of 2005. The physical, chemical and biological variables of the water were measured and efficiency rates of the system were made. The constructed wetlands system mainly showed efficient removal rates in sulphate (52%), turbidity (86%), BDO (41 - 64%), total phosphorus (51 - 68%), organic nitrogen (51,7%), nitrite (77,8%) and ammonia nitrogen (57 - 84%). The settling channel and macrophyte-based system presented a high removal performance for most of the variables analyzed in the work, contributing with the largest portion in the total removal rate of the system. During the study period, probably due to the lack of system management, the return of nutrients previously uptaken (N, P, Fe) by macrophytes for the water column was observed with the decay of aging plants and anaerobic conditions in the HDS system. Those factors, added with the presence of the park´s animals attracted for the rice, contributed with the low performance of macrophyte-based and HDS system in the removal of color, turbidity, total iron and coliforms in some months of collection. For most of the analyzed variables, the water treated by the constructed wetlands system reached the limits and patterns established by the Resolution CONAMA 357/2005 for fresh water of class 2 (BRAZIL, 2005). However, due to the obtained data, the treated water cannot be totally classified as class 2, although it is expected that with the stabilization of the system and appropriate handling, the treated water reach the demanded characteristics and can be classified in fresh water of class 2.