This research aimed at improving p-xylene selectivity in toluene disproportionation over ZSM-5 zeolite by exploring the effect of crystal size and various post synthetic modification methods. A comprehensive study of the effect of different modifications on the physicochemical properties of ZSM-5 was investigated using X-ray diffraction (XRD), pyridine adsorption, Fourier transform infra-red (FTIR), 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR), BET surface area by N2 adsorption, inductively coupled plasma (ICP) and scanning electron microscopy (SEM). The catalytic performance of each catalyst was studied in a fixed bed reactor at a temperature 475 °C, WHSV 3-83 h-1 and two different pressures (1 and 10 bar). ZSM-5 zeolites with different crystal sizes (5, 50 and 100 ÂÂμm) were synthesized in house and compared with the commercially obtained ZSM-5 having a crystal size of 0.5 ÂÂμm. The increase in crystal size improved p-xylene selectivity which was attributed to the diffusion constraints imposed by the longer diffusion path lengths of large crystals. The highest p-xylene selectivity (58 %) was achieved over ZSM-5 with the largest crystal size 100 ÂÂμm at the highest WHSV 83 h-1. However, it was accompanied by a low conversion (2 wt. %). ZSM-5 with crystal size of 5 ÂÂμm delivered the best results in terms of the combination of para-selectivity (40 %) and toluene conversion (15 wt. %). The p-xylene produced in the channels of ZSM-5 can quickly isomerise to o-xylene and m-xylene on the external unselective acid sites. Different post modification methods were applied in this study in attempt to suppress the fast isomerization reaction by deactivating the external acid sites. This was achieved to some extent by depositing an inert silica layer using different silica agents, amounts and number of modification cycles and as a result p-xylene selectivity was significantly improved (84 %), especially over large crystals 5 ÂÂμm. The decrease in Brà̧nsted acidity (FTIR) suggested the success of the silylation method. Furthermore, impregnation of lanthanum and phosphorus on ZSM-5 improved p-xylene selectivity (40 %). FTIR measurements showed a drastic drop in the number of Brà̧nsted and Lewis acid sites after loading phosphorus which led to a large reduction in toluene conversion. Lanthanum impregnation had less effect on conversion and increased selectivity with decreased Brà̧nsted sites and pore volume reduction showed by N2 adsorption suggesting some pore narrowing. There are several approaches that can be considered in future to further improve p-xylene selectivity. Improving the synthesis of large crystals to balance acidity and crystal size can lead to the enhancement of p-xylene selectivity. Also, performing toluene disproportionation on optimised pre-coked ZSM-5 large crystals at high pressure can help to maintain the conversion while increasing p-xylene selectivity. Another approach would be to apply silylation modification to extruded large crystals ZSM-5.

In this work, the steady-state performance of zeolite-based (Cu-ZSM-5) and vanadium-based honeycomb monolith catalysts was investigated in the selective catalytic reduction process (SCR) for NO removal using NH3. The aim was to delineate the effect of various parameters including pretreatment of the catalyst sample with H2, NH3-to-NO ratio, inlet oxygen concentration, and space velocity. The concentrations of the species (e.g. NO, NH3, and others) were determined using a Fourier Transform Infrared (FTIR) spectrometer. The temperature was varied from ambient (25 C) to 500 C. The investigation showed that all of the above parameters (except pre-treatment with H2) significantly affected the peak NO reduction, the temperature at which peak NO reduction occurred, and residual ammonia left at higher temperatures (also known as 'NH3 slip'). Depending upon the particular values of the parameters, a peak NO reduction of around 90% was obtained for both the catalysts. However, an accompanied generation of N2O and NO2 species was observed as well, being much higher for the vanadium-based catalyst than for the Cu-ZSM-5 catalyst. For both catalysts, the peak NO reduction decreased with an increase in space velocity, and did not change significantly with an increase in oxygen concentration. The temperatures at which peak NO reduction and complete NH3 removal occurred increased with an increase in space velocity but decreased with an increase in oxygen concentration. The presence of more ammonia at the inlet (i.e. higher NH3-to-NO ratio) improved the peak NO reduction but simultaneously resulted in an increase in residual ammonia. Pretreatment of the catalyst sample with H2 (performed only for the Cu-ZSM-5 catalyst) did not produce any perceivable difference in any of the results for the conditions of these experiments.

This thesis focus on the analysis of spin-lattice NMRD relaxation profilesmeasured in various complex systems such as proteins, zeolites and ionicliquids. Proton, deuterium and fluoride T1-NMRD relaxation profiles wereobtained from a fast-field cycling (FFC) instrument. It is found that alsopossible to obtain NMRD profiles from the molecular dynamics (MD)simulation trajectories. NMRD Profiles were analyzed by using differentrelaxation models, such as the Solomon-Bloembergen-Morgan (SBM) theoryand the Stochastic Liouville (SL) theory. Paper I described the hydration of protein PrxV obtained from a MDsimulation, and compared with the picture emerges from an analysis byusing a generally accepted relaxation model [appendix C]. The result showsthat the information from NMRD analysis is an averaged picture of watermolecules with similar relaxation times; and the MD simulations containsinformation of all types of interested water molecules with differentresidence times. In paper II NMRD profiles have been used to characterize the hydration ofthe oxygen-evolving complex in state S1 of photosystem II. NMRDexperiments were performed on both intact protein samples and Mndepletedsamples, and characteristic dispersion difference were foundbetween 0.03 MHz to 1 MHz; approximately. Both the SBM theory and theSL theory have been used to explain this dispersion difference, and it isfound that this is due to a paramagnetic enhancement of 1-2 water moleculesnearby ~10 Å from the spin center of the Mn4CaO5 cluster. The result showsthe reorientation of the molecular cluster is in μs time interval. Whencompare these two theories, the SL theory presented a better interpretationbecause parameters obtained from the SBM theory shows they didn’t fulfilthe presupposed perturbation criterion (the Kubo term). Paper III deals with the water dynamics in the restricted/confined spaces inthe zeolite samples (H-ZSM-5 and NH4-ZSM-5) and obtained by proton anddeuterium spin-lattice NMRD profiles. The results show that the spin-latticeNMRD can be used to characterize various zeolites. The temperature has aweak effect on the relaxation rate R1, but the change of different counter ionsmay change the hydration and the translational diffusion pores and givedifferent R1. Proton and fluoride NMRD profiles and MD simulations were both used tostudy the dynamics of BMIM[PF6] in paper IV. Results indicate the reorientation of the molecules are in the ns time regime, and the effectivecorrelation time obtained from 1H and 19F are the same. From the MDsimulation it is found the reorientation of [PF6]- ions is much faster (in ps)compare with BMIM+ ion which moves in the ns time range. With previous results, the FFC NMRD profiles are indeed very informativetools to study the molecular dynamics of complex systems. The MDsimulation can be used as a complementary method to obtain detailedinformation. By combine these two methods, it provide a more colorfulpicture in the study of protein hydration and liquid molecular dynamics.

Made available in DSpace on 2016-06-02T20:36:28Z (GMT). No. of bitstreams: 1 3358.pdf: 2280113 bytes, checksum: 836e1809b57b84adf512d641f8aa3180 (MD5) Previous issue date: 2010-09-27 / Financiadora de Estudos e Projetos / The current market demands make with what Brazilian agribusiness search improvements in processes and new materials to reduce waste, pollution and biological contamination. Mainly materials that more are easily degraded by the action of microorganisms or abiotic factors.It is known that the synthetic plastics are difficult of degrade and one alternative to decrease their use and hence the contamination of the environment is the introduction of biodegradable plastics such as thermoplastic starch (TPS). Thus, this study aimed to develop nanocomposites of TPS, seeking conditions for the incorporation of nanozeólitas (ZSM-5) that could confer properties related to control hydrophilicity. The work started in the construction of hydrothermal reactors for the standardization of zeolite. The synthesis gel was based on a molar ratio has been already studied (Al2O3: 60SiO2: 11TPAOH: 900H2O). The hydrothermal treatment was done in five different ways, varying temperatures (100, 150 and 200oC) and time (24, 48 and 72 hours). The five samples were characterized by X-ray diffraction, nitrogen physisorption, particle size analysis by light scattering and scanning electron microscopy at high resolution. The best condition of formation of zeolite phase was 200oC for 24 hours. This synthesis was repeated and characterized by four times to obtain 27g of nanozeólitas to be used to obtain the composite processing. The compositions of thermoplastic starch and nanozeólita were made in a torque rheometer with mass ratios of 0, 2, 4, 6, 8 and 10% ZSM-5 TPS, keeping fixed the final mass of the mixture, 45 g. Thermogravimetric analysis of films showed that the increased load of nanozeolites in the matrix polymer no caused change in the temperatures of the events that occur in the mass losses. The results of dynamic mechanical thermal analysis showed no significant variations in glass transition temperatures of the glycerol and starch, which were influenced by the increase of ratio glycerol / starch. The analysis of tensile mechanics showed that up to 6% zeolite added there is no impairment of mechanical properties of films, above this value occurs a lower elastic modulus of the composite and consequently an increase in the deformation of the material also caused by variations in the relationship between ratio glycerol and starch. Statistical analysis of variance for this experiment confirmed the previous supposition. The pervaporation water vapor showed that the increased load of zeolite in the polymer matrix facilitated the passage of water through the polymer matrix due to the presence of the channels characteristic of the zeolite. Statistical analysis of variance showed that the most significant change was the 10% zeolite added. Through these studies we can see that it is possible to incorporation of zeolite in thermoplastic starch using the same equipment used in processing of synthetic plastics. This study also showed that the incorporation of zeolite modified the hydrophilicity of the material facilitating the passage of water vapor by the matrix polymer by channels of zeolite. / As exigências do mercado atual fazem com que a agroindústria brasileira busque melhorias nos processos e novos materiais a fim de diminuir o desperdício, a poluição e a contaminação biológica. Principalmente materiais que sejam mais facilmente degradados por meio da ação de microorganismos ou fatores abióticos. Sabe-se que os plásticos sintéticos atuais são de difícil degradação e uma alternativa para a diminuição do seu uso e por conseqüência a contaminação do meio ambiente é a introdução de plásticos biodegradáveis tal como o amido termoplástico (TPS). Sendo assim, objetivou-se neste trabalho o desenvolvimento de nanocompósitos de TPS, buscando condições para a incorporação de nanozeólitas (ZSM-5) que pudessem conferir propriedades relacionadas ao controle de hidrofilicidade. O trabalho teve início na construção de reatores hidrotérmicos para a padronização da zeólita. O gel de síntese teve como base uma proporção molar já estudada (Al2O3:60SiO2:11TPAOH:900H2O). O tratamento hidrotérmico foi feito de cinco formas diferentes, variando temperatura (100, 150 e 200oC) e tempo (24, 48 e 72 horas). As cinco amostras foram caracterizadas por difração de raios X, fisissorção de nitrogênio, análise de tamanho de partículas por espalhamento de luz e microscopia eletrônica de varredura de alta resolução. A melhor condição de formação da fase zeolítica foi de 200oC por 24 horas. Esta síntese foi repetida e caracterizada por quatro vezes para a obtenção das 27g de nanozeólitas a serem utilizadas na obtenção do compósito polimérico. As composições de amido termoplástico e nanozeólita foram feitas em um reômetro de torque com proporções em massa de 0, 2, 4, 6, 8 e 10% de ZSM-5 em TPS, mantendo fixa a massa final da mistura em 45 g. As análises termogravimétricas dos filmes mostraram que o aumento da carga de nanozeólita na matriz polimérica não houve mudanças nas temperaturas dos eventos em que ocorrem as perdas de massa. Os resultados das análises térmicas dinâmico-mecânica mostraram que não houve variações significativas nas temperaturas de transições vítreas tanto do glicerol como do amido, que foram influenciadas pelo aumento da relação glicerol/amido. As análises de resistência à tração mecânica mostraram que até 6% de zeólita adicionada não há comprometimento das propriedades mecânicas dos filmes, já acima ocorre um abaixamento no modulo elástico do compósito e consequentemente um aumento na deformação do material causado também pela variação na relação entre glicerol e amido. A análise estatística de variância para esse experimento comprovou essa suposição. A pervaporação ao vapor de água mostrou que o aumento da carga de zeólita na matriz polimérica facilitou a passagem de água pela matriz polimérica, isto devido à presença dos canais característicos da zeólita. A análise estatística de variância mostrou que a variação mais significativa foi a de 10% de zeólita adicionada. Por meio desses estudos podese observar que é possível a incorporação de zeólita em amido termoplástico utilizando os mesmos equipamentos utilizados no processamento dos plásticos sintéticos. Esse estudo também mostrou que a incorporação da zeólita modificou a hidrofilicidade do material facilitando a passagem do vapor de água através dos canais da zeólita.

Made available in DSpace on 2016-06-02T19:55:32Z (GMT). No. of bitstreams: 1 4445.pdf: 6135592 bytes, checksum: 9a1ebffa2ca083786400ffa973e8b424 (MD5) Previous issue date: 2012-04-27 / Universidade Federal de Sao Carlos / Due to their potential as acid catalyst and hydrothermal stability, USY, ZSM-5 and modernite zeolites are widely used in several processes of petroleum refining and petrochemical industries. With the discovery of new reserves in Brazil, the petroleum industry must adequate its technology to be able to process heavy oil fractions and satisfy the increased demand for more valuable derivatives (gasoline, diesel and olefins). To achieve this, a better performance of such zeolites needs to be reach by improvement of the active sites accessibility and/or diminishing the diffusion path inside of their microporous system. In this context, the objective of this research was to synthesize ZSM-5 zeolites with hierarchical pore structure and evaluate their potential as acid catalyst in the cracking of hydrocarbons, using cyclohexane as model molecule. In the synthesis of these materials, Black Pearls 2000 carbon and an organosilane surfactant molecule were employed as structure-directing agent for mesopores formation. Zeolites were characterized by X-ray fluorescence, X-ray diffraction, nitrogen physisorption, small-angle X-ray scattering, scanning electron microscopy, nuclear magnetic resonance of 27Al nucleus, Fourier transformed infrared spectroscopy and ammonium temperature programmed desorption. The properties and acid activity of the synthesized zeolites were compared with a ZSM-5 zeolite without mesopores. The results revealed that the used synthesis methodologies were effective in the formation of crystals of ZSM-5 zeolite containing the intrinsic micropores of the MFI structure combined with the presence of intracrystalline mesopores. The Black Pearls 2000 carbon generated mesopores that were an inverse replica of the carbon particles with an average diameter of 12 nm and the amphiphilic surfactant mesopores with diameters of about 4 nm. The cracking of cyclohexane showed that the solids with hierarchical structure of pores preserved the acid potential of ZSM-5 zeolites, with all the micro-mesoporous zeolites presenting similar catalytic behaviour related with the yield and selectivity in the considered reaction. Other hand, the presence of mesopores favoured the formation of products resulting from isomerization and hydrogen transfer reactions. / Devido ao seu potencial como catalisador ácido e estabilidade hidrotérmica, as zeólitas USY, ZSM-5 e mordenita são utilizadas em diversos processos no refino de petróleo e em petroquímica. Com a descoberta de novas jazidas no Brasil, a indústria do petróleo deve se adequar tecnologicamente para ter capacidade de processar frações pesadas e atender o aumento da demanda por derivados de maior valor agregado (gasolina, diesel e olefinas). Para isso, um desempenho mais eficiente no uso dessas zeólitas pode ser alcançado melhorando a acessibilidade aos sítios ativos e/ou reduzindo o caminho difusional no interior do seu sistema microporoso. Nesse contexto, o objetivo do estudo foi sintetizar zeólitas ZSM-5 com estrutura hierárquica de poros e avaliar seu potencial como catalisador ácido por meio do craqueamento de cicloexano, utilizado como molécula modelo. Na síntese desses materiais foram utilizados o carbono Black Pearls 2000 e uma molécula surfactante organossilano, como agentes direcionadores da formação de mesoporos. As zeólitas foram caracterizadas por difração de raios X, fisissorção de nitrogênio, espalhamento de raios X a baixos pequenos, microscopia eletrônica de varredura e transmissão, ressonância magnética nuclear do núcleo 27Al, fluorescência de raios X, espectroscopia na região do infravermelho com transformada de Fourier e dessorção de amônia a temperatura programada. As propriedades e atividade ácida das zeólitas sintetizadas foram comparadas às de uma zeólita ZSM-5 isenta de mesoporosidade. Os resultados revelaram que as metodologias de síntese foram efetivas na formação de cristais de zeólita ZSM-5 contendo a microporosidade intrínseca da estrutura MFI combinada à presença intracristalina de mesoporos. O carbono Black Pearls 2000 gerou mesoporos que foram uma replica inversa das partículas desse material com diâmetro médio de 12 nm e o surfactante anfifílico mesoporos com diâmetros em torno de 4 nm. O craqueamento de cicloexano mostrou que os sólidos com estrutura hierárquica de poros mantiveram o potencial ácido de zeólitas ZSM-5, sendo os rendimentos e seletividades dessa reação similares para todas as zeólitas micro-mesoporosas sintetizadas. A presença de mesoporos favoreceu, entretanto, a formação de produtos resultantes de isomerização e transferência de hidrogênio.

Made available in DSpace on 2016-06-02T19:56:30Z (GMT). No. of bitstreams: 1 1801.pdf: 7196962 bytes, checksum: d8036f105e4f745f6d5cca6487bfd320 (MD5) Previous issue date: 2008-04-04 / Universidade Federal de Minas Gerais / The use of zeolites in the cracking of hydrocarbons is limited because the molecules higher than 0.74 nm do not diffuse in their micropores. In the other hand, molecular sieves as MCM-41, MCM-48 ou SBA-15, whose diameters are up 10 nm for the two formers and up to 30 nm for the last, have low hydrothermal stability and catalytic activity. To overcome those limitations, many studies are devoted to prepare materials, which can combine the high activity of zeolites with the better accessibility of the mesoporous materials. Among the possible methods, the synthesis of zeolites in confined spaces (nanocasting) it is seem as a powerful alternative. In this method: 1) a mesoporous or non-porous silica is impregnated with an organic compound, which act as a carbon precursor, after being carbonized; 2) the porous carbon is subsequently obtained by treatment with hydrofluoric acid or alkaline hydroxides; 3) the porous of the carbon are filled with the zeolite synthesis gel, which is formed after crystallization; 4) finally, the mold of the carbon and the template of the zeolite microstructure are eliminated by calcination. In the present work, it was used the above described method for the synthesis of nanocasting ZSM-5 zeolites using porous carbon, which were prepared from non-porous or mesoporous silica moulds (MCM-41, MCM-48 e SBA-15). The XRD of the prepared zeolites did not show diffraction peaks in the low angle region (< 5°2&#952;), showing that the inverse replica of the mesoporous silicas was not obtained. However, the nitrogen sorption measurements evidenced the presence of mesoporous, which resulted from the carbon nanotubes occluded during the ZSM-5 crystals formation. The mesopores observed in the Znp, nanocast from non-porous silica, were attributed to the inter-crystalline spaces generated by the agglomeration of ZSM-5 nanocrystals. The mesoporous formation in the ZSM-5 zeolites during the crystallization in a confined space (nanocating) was considerately favored by the ageing of the synthesis gel at the laboratory temperature and without stirring. That procedure allows the preparation at 180 °C of ZSM-5 zeolites with high crystallinity and in a lower time. Nevertheless, as verified by 27Al-NMR, the aluminum was incorporated partially in the zeolite microstructure, remaining as alumina in the crystal surface, which leads to a lower activity in the n-decane cracking when compared with a conventional ZSM-5 zeolite with a similar Si/Al ratio. / A utilização de zeólitas no craqueamento de hidrocarbonetos é limitada devido a não permitir a difusão de moléculas de tamanho maior que o diâmetro de seus microporos (< 0,74 nm). Por outro lado, as peneiras moleculares mesoporosas, como a MCM-41, MCM-48 ou SBA-15 com diâmetro de poros de até 10 nm, no caso das duas primeiras, e de até 30 nm no caso da última, possuem baixas estabilidade hidrotérmica e atividade catalítica. Para superar essas restrições, estuda-se a preparação de materiais que combinem a elevada atividade catalítica das zeólitas com a melhor acessibilidade dos materiais mesoporosos. Dentre os métodos possíveis, a síntese de zeóltas em espaço confinado (nanomoldagem), surge como uma potencial alternativa. Nessa técnica: 1) uma silica mesoporosa ou não porosa é impregnada com um composto orgânico precursor de carbono, sendo o sólido posteriormente carbonizado; 2) o carbono poroso é obtido após dissolução da sílica com ácido fluorídrico ou hidróxidos alcalinos; 3) os poros do carbono são preenchidos com o gel de síntese da zeólita, a qual se forma após cristalização; 4) finalmente o molde de carbono e o agente direcionador da microestrutura são eliminados via calcinação. No presente trabalho, utilizou-se a técnica descrita para a síntese de zeólitas ZSM-5 nanomoldadas em carbonos porosos, os que foram obtidos utilizando como molde sílicas não porosas ou mesoporosas (MCM-41, MCM-48 e SBA-15). Os difratogramas de raios X das zeólitas preparadas não apresentaram picos de difração em ângulos menores que 5°(2&#952;), mostrando que o ordenamento das fases mesoporosas não foi replicado, porém, os resultados de fisissorção de nitrogênio indicaram a presença de mesoporos, sugerindo que nanotubos de carbono formados nos mesoporos dos moldes de sílica foram ocluídos nos cristais da ZSM-5. Os mesoporos observados nas zeólitas Znp, nanomoldadas em carbono obtido da sílica não porosa, foram atribuídos aos espaços intercristalinos resultantes do empacotamento de cristais nanométricos da zeólita ZSM-5. A formação de mesoporos nas zeólitas ZSM-5 durante o processo de cristalização em espaço confinado (nanomoldagem) foi consideravelmente favorecida pelo envelhecimento do gel de síntese à temperatura ambiente e sem aplicação de agitação. Esse procedimento permitiu a obtenção a 180 °C de zeólitas com alta cristalinidade e em menor tempo de cristalização. Entretanto, como verificado por 27Al-RMN, o alumínio foi incorporado parcialmente na estrutura da zeólita, permanecendo como alumina na superfície dos cristais, o que provocou menor atividade para o craqueamento de n-decano quando comparado com uma zeólita ZSM-5 convencional com relação Si/Al próxima.

Submitted by Luiz Gustavo Possato null (gustavopossato@gmail.com) on 2017-01-18T15:52:06Z No. of bitstreams: 1 TeseFinal.pdf: 6256513 bytes, checksum: 5dc8457c0e05e4ba946b7acf2ad82ff8 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-01-20T18:01:51Z (GMT) No. of bitstreams: 1 possato_lg_dr_araiq.pdf: 6256513 bytes, checksum: 5dc8457c0e05e4ba946b7acf2ad82ff8 (MD5) / Made available in DSpace on 2017-01-20T18:01:51Z (GMT). No. of bitstreams: 1 possato_lg_dr_araiq.pdf: 6256513 bytes, checksum: 5dc8457c0e05e4ba946b7acf2ad82ff8 (MD5) Previous issue date: 2016-12-12 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O aumento da produção do biodiesel tem levado à formação de grandes quantidades de glicerol, o qual pode ser convertido em compostos de interesse petroquímico, como o ácido acrílico. A primeira parte consiste no estudo do comportamento de catalisadores bifuncionais V2O5/MFI com propriedades ácidas e oxidantes aplicados na desidratação oxidativa do glicerol em fase gasosa. Um dos principais produtos da reação foi o ácido acrílico (17%), produzido pela desidratação do glicerol à acroleína sítio ácido e sua subsequente oxidação em um sítio redox. A comparação da impregnação por via úmida com sulfato de vanadila (VOSO4) e metavanadato de amónio (NH4VO3) mostrou que a impregnação com VOSO4 forneceu o melhor desempenho para a conversão do glicerol e seletividade para o ácido acrílico. Medidas de XPS dos catalisadores frescos e usados auxiliaram a elucidação da dinâmica dos ciclos redox de óxido de vanádio durante a oxidação de acroleína. A presença de vanádio na zeólita aumentou a estabilidade do catalisador devido à capacidade multifuncional das espécies de óxido de vanádio para converter a acroleína e ácido acrílico e como catalisador para a oxidação dos produtos coqueificados da reação. Análises qualitativas e quantitativas do coque depositado nos catalisadores usados foram realizadas utilizando RMN de 13C e termogravimetria. A segunda parte está relacionada com a zeólita ZSM-5 (estrutura MFI, Si/Al = 40) tratada utilizando NaOH e ou ácido oxálico, ou HCI visando a obtenção de materiais com características hierárquicas diferentes, seguida pela impregnação com VOSO4 (precursor de V2O5) para gerar sítios redox. O impacto dos vários tratamentos na eficiência e a estabilidade dos catalisadores para a conversão de glicerol em acroleína e ácido acrílico (25%) foi investigada e correlacionada com porosidade catalisador, acidez e composição química. Os estudos demonstraram que o desempenho catalítico dos materiais dependeu das propriedades ácidas e texturais das zeólitas, que influenciaram tanto a dispersão de V2O5 quanto a sua interação com os sítios ácidos do suporte zeolítico A terceira parte apresenta um estudo in situ das fases cristalinas formadas durante o tratamento térmico de precursores de óxidos de vanádio e molibdénio, medidos por difração de raios X. O interesse na especiação de óxidos mistos MoxVyOz reside no excelente desempenho catalítico desses materiais para a conversão seletiva do glicerol ao ácido acrílico. A estrutura cristalográfica das fases ativas de MoxVyOz influencia diretamente sobre a valência do vanádio e, consequentemente, altera as dinâmicas dos estados de oxidação do vanádio durante a reação catalítica. O tratamento térmico de uma mistura de precursores de Mo e V sob atmosferas oxidante ou inerte revelou a maior formação de MoV2O8 (61%) ou de Mo4V6O25 (29%), respectivamente, a uma temperatura final de 500 °C. A fase mais ativa para a formação do ácido acrílico foi MoV2O8 (3,5 vezes mais ativa do que os óxidos dos metais separados), devido à instabilidade da fase em relação ao oxigênio de rede na temperatura da reação. O ciclo de redução e oxidação do vanádio em MoV2O8 durante a reação auxiliou a dinâmica da criação de vacâncias de oxigênio, resultando em 97% de conversão de glicerol e 32% de seletividade ao ácido acrílico. A quarta e última parte é relacionada à dispersão dos óxidos mistos de vanádio e molibdênio na matriz zeolítica. / The increased production of biodiesel has led to the formation of large amounts of glycerol, which can be converted into compounds of petrochemical interest, such as acrylic acid. The first part consists in the study of catalytic behavior of bifunctional V2O5/MFI catalysts with acid and oxidizing properties investigated for the gas-phase oxidehydration of glycerol. One of the main reaction products was acrylic acid, produced by dehydration of glycerol to acrolein at an acidic site and subsequent oxidation at a redox site. Comparison of wet impregnation with vanadyl sulfate (VOSO4) and ammonium metavanadate (NH4VO3) showed that VOSO4 impregnation provided the best performance for the conversion of glycerol and selectivity towards acrylic acid (17%). XPS measurements of the fresh and spent catalysts enabled elucidation of the dynamic redox cycles of vanadium oxide during oxidation of acrolein. The presence of vanadium in the zeolite improved the catalyst lifetime, because of the multifunctional ability of the vanadium oxide species to convert acrolein to acrylic acid and act as catalyst for the oxidation of coked glycerol products. Qualitative and quantitative analyses of the coke deposited in the spent catalysts were performed using 13C NMR and thermogravimetry, respectively. The second chapter is related to ZSM-5 zeolite (MFI structure, Si/Al = 40) treated using NaOH and either oxalic acid or HCl to obtain hierarchical materials with different characteristics, followed by impregnation with vanadium oxides (V2O5) to generate redox-active sites. The impact of the multiple treatments on the efficiency and stability of the catalysts in the conversion of glycerol to acrolein and acrylic acid (25%) was investigated and correlated with catalyst porosity, acidity, and chemical composition. The studies showed that the catalytic performance of the materials depended on the acidic and textural properties of the zeolites, which influenced both the dispersion of V2O5 and its interaction with the acid sites of the supporting zeolites. The third part presents an in situ study of the crystallographic phases formed during the thermal treatment of precursors of vanadium and molybdenum oxides, measured under synchrotron X-ray diffraction. The interest in the speciation of MoxVyOz mixed oxides lies in the excellent catalytic performance of these materials for the selective conversion of glycerol to acrylic acid employing the oxidehydration reaction. The crystallographic structure of the active phases of MoxVyOz directly influences on the nearby metal valence and, therefore, on the dynamic changes in metal oxidation states during the catalytic reaction. The thermal treatment of a mixture of the precursors of Mo and V under oxidizing or inert atmospheres revealed the major formation of 61 % of MoV2O8 or 29 % of Mo4V6O25, respectively, at a final temperature of 500 ºC. The most active phase for acrylic acid formation was MoV2O8 (3.5 times more active than the separate metal oxides), due to the instability of the phase with respect to framework oxygen at the reaction temperature. The cycle of reduction and oxidation of the vanadium in MoV2O8 during the reaction caused dynamic creation of oxygen vacancies, resulting in 97 % conversion of glycerol and 32 % selectivity towards acrylic acid. The fourth and last part is related to the mixed oxides dispersed on the zeolite support. / FAPESP: 2013/10204-2

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-04-11T19:34:25Z No. of bitstreams: 1 JulianaElionaraBezerraCosta_TESE.pdf: 2543108 bytes, checksum: 556e8d7316f4202efa7113ded946013c (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-04-12T22:40:15Z (GMT) No. of bitstreams: 1 JulianaElionaraBezerraCosta_TESE.pdf: 2543108 bytes, checksum: 556e8d7316f4202efa7113ded946013c (MD5) / Made available in DSpace on 2018-04-12T22:40:16Z (GMT). No. of bitstreams: 1 JulianaElionaraBezerraCosta_TESE.pdf: 2543108 bytes, checksum: 556e8d7316f4202efa7113ded946013c (MD5) Previous issue date: 2017-12-18 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Alguns res?duos, provenientes das mais variadas atividades, podem ser reaproveitados, diminuindo o efeito dos impactos ambientais ocasionados pela m? disposi??o dos mesmos no meio ambiente. Os res?duos classificados com biomassa lignocelul?sica, podem ser convertidos em produtos qu?micos e combust?veis a partir da pir?lise r?pida convencional, gerando como produto principal o bio-?leo com caracter?sticas diretamente ligadas as caracter?sticas da biomassa de origem que podem ser melhoradas a partir do uso de catalisadores. Neste trabalho foram sintetizados catalisadores do tipo ZSM-5 e HZSM-5, utilizando res?duos de p? de granito, p? de vidro, diatomita e cinza da casca do arroz como fontes alternativas e tamb?m um catalisador utilizando fonte convencional de S?lica e Alum?nio. O objetivo da s?ntese desses materiais ? utiliz?-los como catalisador na pir?lise da fibra do coco visando a obten??o de produtos com maior valor agregado, reduzindo a produ??o de compostos oxigenados. A biomassa utilizada foi caracterizada por an?lise imediata, densidade, an?lise elementar, Teor de Celulose, hemicelulose e lignina, Poder calor?fico, TG/DTG, DRX, FT-IR e FRX afim de analisar o potencial energ?tico da mesma. Os precursores de S?lica e Alum?nio foram submetidos a an?lises de FRX, DRX, e os catalisadores foram caracterizados por TG/DTG, DRX, FT-IR, MEV e BET. Nos resultados de pir?lise convencional da fibra do coco observou a grande produ??o de produtos oxigenados, a maior parte deles fen?is e nos resultados das pir?lise catal?tica foi poss?vel observar a diminui??o desses produtos, provando a efici?ncia dos catalisadores utilizados. / Some waste, from the most varied activities, can be reused, reducing the effect of these impacts, usually caused by poor disposal in the environment. The residues classified with lignocellulosic biomass can be converted into chemical products and fuels from the conventional fast pyrolysis, generating as main product the bio-oil. This generally presents some undesirable characteristics directly linked to the characteristics of the source biomass, which decrease its energy efficiency. The use of catalysts allows the reduction of these undesirable products and improves the final quality of the bio oil. As a result, ZSM-5 and HZSM-5 catalysts were synthesized using granite powder, glass powder, diatomite and rice husk ash as alternative sources of silica and aluminum; was also synthesized using a conventional silica and aluminum source, serving as a standard for the others. . The objective of the synthesis of these materials is to use them as a catalyst in the pyrolysis of coconut fiber in order to obtain products with higher added value, reducing the production of oxygenated compounds. The biomass used was characterized by immediate analysis, density, elemental analysis, cellulose content, hemicellulose and lignin, calorific power, TG / DTG, XRD, FT-IR and FRX in order to analyze the energy potential of the same. Silica and Aluminum precursors were subjected to FRX, XRD analyzes, and the catalysts were characterized by TG / DTG, DRX, FT-IR, MEV and BET. In the results of conventional pyrolysis of the coconut fiber, it was observed the great production of oxygenated products, most of them phenols and in the results of the catalytic pyrolysis it was possible to observe the decrease of these products, proving the efficiency of the catalysts used.

Fossil based energy resources are dominating the world’s primary energy consumption for the last century. However, with decreasing crude oil reservoirs and the role they play in global warming by emitting greenhouse gases, the focus has been turned towards improved utilization of renewable resources and the need for new, sustainable fuels and chemicals is more urgent than ever. Biomass is a carbon neutral resource that can be used to produce biofuels and other useful chemicals. One such chemical is 1-butanol (or simply butanol), which has great potential as a gasoline substitute because of its favorable fuel properties. Butanol can be produced from acetone, butanol and ethanol (ABE) fermentation using e.g. Clostridium acetobutylicum. However, the concentration of butanol in fermentation in the resulting broth is limited to ca. 20 g/L due to its toxicity for microorganisms. Butyric acid is a precursor to butanol, which is produced prior to butanol in ABE fermentation. Butyric acid is an important industrial chemical, which can be further converted into a number of commercial compounds e.g. acetate butyrate, butyl acetate and butanol. Arginine is a semi-essential amino acid that has vast applications in the field of pharmaceutical and food industry. In addition, arginine can replace inorganic nitrogen as nitrogen source in fertilizers. It can be produced via fermentation of sugars using engineered microorganism like E. Coli, but like butanol its concentration is restricted to approximately 12 g/L. Due to low concentration of these useful chemicals in the resulting fermentation broths recovery of these chemicals remain challenging with today’s options and therefore  novel recovery process should be developed. In this study, zeolite adsorbents were used to recover butanol, butyric acid and arginine from model and real fermentation broths. Zeolite MFI adsorbent efficiently adsorbed butanol from model solutions with a saturation loading of 0.11 g/g- zeolite. On the other hand, adsorption of butyric acid was found to be strongly pH dependent, with high adsorption below and little adsorption above the pKa value of the acid. A structured adsorbent in the form of steel monolith coated with a silicalite-1 film was also used and performance was evaluated by performing breakthrough experiments at room temperature using model ABE fermentation broths and the results were compared with those obtained using traditional adsorbent sin the form of beads. Desorption studies showed that a high quality butanol product with purity up to 95.2% for butanol-water system and 88.5% for the ABE system can be recovered with the structured silicalite-1 adsorbent. Further, zeolite X adsorbents in the form of powder and extrudates was used to recover arginine from a real fermentation broth and also from aqueous model solutions. To the best of our knowledge, this is the first time recovery of arginine from real fermentation broths using any type of adsorbent is reported. Arginine loading of 0.15 g/g was observed at pH 11 using zeolite X powder. The selectivity for arginine over ammonia and alanine from the fermentation broth at pH 11 was 1.9 and 8.3, respectively, for powder and 1.0 and 4.1, respectively, for extrudates. Synthesis gas (CO + H2) can be produced e.g.by gasification of lignocellulose biomass. This synthesis gas can be used to produce methanol, which subsequently may be converted into gasoline using zeolite ZSM-5 catalyst. However, during Methanol to Gasoline (MTG) process, undesirable carbon residue (coke) is formed that gradually reduces the activity of catalyst. It was hypothesized that intracrystalline defects in the zeolite formed during conventional synthesis may accelerate the deactivation rate by coke formation. In this work, a novel ZSM-5 zeolite catalyst essentially free of intracrystalline defects was synthesized and evaluated in the  MTG reaction,. The novel catalyst showed significantly higher resistance towards deactivation by coke formation as compared to a reference catalyst containing defects.

Zeolites and zeolite membranes are two important advanced chemical materials which are widely used in chemical processes. The manufacture of these materials usually involves the use of expensive chemicals. This study involves the use of Ahoko Nigerian kaolin (ANK) as precursor material for the development of zeolites and zeolite membranes. The synthesis of zeolite A, Y and ZSM-5 was successfully obtained following a sequence, collection of the raw clay from Nigeria, metakaolinization, dealumination and actual hydrothermal synthesis of the zeolites. Raw ANK was refined using sedimentation technique and about 97% kaolin was recovered from the raw sample. A novel metakaolinization technique was developed to convert kaolin into a reactive metastable phase. Amorphous metakaolin was obtained at a temperature of 600°C and exposure time of 10 min. This is a significant result because previous studies use higher temperatures and longer exposure times for the metakaolinization step. The metakaolin was used to prepare a number of different zeolites under various conditions. Highly crystalline zeolite A was obtained at an ageing time of 12 h, crystallization time of 6 h and crystallization temperature of 100oC. Zeolite Y was obtained at an ageing time of 3 h, crystallization time of 9 h and crystallization temperature of 100oC. Zeolite Y was also synthesised by using a dealuminated kaolin and highly crystallized zeolite Y with Si/Al ratio of 1.56 and BET surface area was obtained of 630 m2/g. ZSM-5 was synthesised using an ageing period of 36 h, crystallization time of 48 h and temperature of 140oC. The results obtained from zeolite powder synthesis from ANK were then used as guide to prepare supported zeolite films and membranes by a hydrothermal method. The effect of the support surface (stainless steel) was investigated using two synthesis methods namely modified in-situ and secondary (seeded) growth. Zeolite A, Y and ZSM-5 films were successfully prepared from ANK for the first time and on two modified supports, etched and oxidised. The zeolite films and membranes developed showed complete coverage on the two supports with the oxidised showing better adhesion and intergrowth. The separation performance of the three developed zeolite membrane was tested by pervaporation of water/ethanol mixture. The results of pervaporation of ethanol/water mixture showed that zeolite A membrane is highly selective towards water mainly because of hydrophilic properties occasioned by the high aluminium content. Zeolite Y membrane show a similar response when their separation performance was evaluated but with less selectivity because of reduced aluminium content. ZSM-5 showed selectivity towards ethanol because of it hydrophobicity allowing only ethanol to permeate. In all the zeolite membranes, the flux is lower in comparison to commercial zeolite membranes due mainly to the thickness of the zeolite layer. Oxidised support membranes showed better performance because of their better interaction between the oxide surface and the aluminosilicate gel. The results show that ANK can successfully be used to prepare zeolites and zeolite membrane.