A síntese de zeólitas a partir de cinzas leves e pesadas de carvão mineral foi realizada por tratamento hidrotérmico alcalino, as quais foram nomeadas ZCL e ZCP, respectivamente. As zeólitas organomodificadas ZML e ZMP foram obtidas a partir da modificação superficial de ZCL e ZCP, respectivamente, utilizando o surfactante catiônico brometo de hexadeciltrimetilamônio. A partir das soluções remanescentes geradas na síntese de ZCL e ZCP foi possível sintetizar duas novas zeólitas. As características físicoquímicas dos nanomateriais zeolíticos sintetizados, bem como de suas respectivas matérias primas, tais como: capacidade de troca catiônica, massa específica, área específica, composição química, mineralógica e morfológica, entre outras, foram determinadas. Os adsorventes ZML e ZMP foram utilizados na remoção dos corantes Azul Direto 71 (DB71) e Rodamina B (RB) de soluções aquosas em sistema de batelada. Desta forma, quatro sistemas DB71/ZML, RB/ZML, DB71/ZMP e RB/ZMP foram investigados. Os modelos de pseudoprimeira ordem e pseudo-segunda ordem foram aplicados aos dados experimentais para o estudo da cinética de adsorção. O modelo de pseudosegunda ordem foi o que melhor descreveu o processo de adsorção de todos os sistemas corante/zeólita organomodificada. O equilíbrio da adsorção foi analisado a partir de quatro modelos de isoterma, sendo eles: Langmuir, Freundlich, Temkin e Dubinin-Radushkevich (D-R). Os resultados mostram que os modelos de Freundlich e Langmuir melhor descreveram os dados experimentais dos sistemas DB71/ZML e DB71/ZMP, respectivamente. Para os sistemas com RB, o modelo de D-R foi o que melhor se ajustou para ambos adsorventes ZML e ZMP. O planejamento fatorial 24 foi aplicado para a análise dos seguintes fatores que influenciam o processo de adsorção: concentração inicial do corante (Co), pH, dose de adsorvente (M) e temperatura (T). De acordo com as condições estudadas concluiu-se, com o intervalo de confiança igual a 95%, que para o sistema DB71/ZML, os fatores e suas interações que mais influenciam foram C0, M, pH, pH*M, pH*C0, M*C0, pH*M*C0, nessa ordem. No sistema DB71/ZMP, a ordem de influência foi: M, C0, pH, pH*M, pH*C0, M*C0, pH*M*C0. Para os sistemas RB/ZML e RB/ZMP, os resultados foram: M, C0, M*C0, pH, pH*M e M, C0, M*C0, respectivamente. O equilíbrio de adsorção foi atingido em cerca de 40 min para todas as amostras. As porcentagens de remoção do DB71 estavam na faixa de 50 80% e 20 50% para ZML e ZMP, respectivamente. A faixa de porcentagens de remoção do RB variou entre 60 80% e 30 50% para ZML e ZMP, respectivamente. / The synthesis of zeolites from mineral coal fly and bottom ash was performed by alkaline hydrothermal treatment, which were named ZFA and ZBA, respectively. Organo-modified zeolites, SMZF and SMZB, were obtained from surface modification of ZFA and ZBA, respectively, using the cationic surfactant hexadecyltrimethylammonium bromide. From the remaining solutions generated in ZFA and ZBA synthesis it was possible to synthesis two new zeolites. The physicochemical characteristics of the synthesized nanomaterials zeolite as well as their respective raw materials, such as cation exchange capacity, density, specific area, chemical composition, mineralogical and morphological, among others, were determined. The adsorbents SMZF and SMZB were used to remove the dyes, Direct Blue 71 (DB71) and Rhodamine B (RB) from aqueous solutions in batch system. Thus, four systems DB71/SMZF, RB/SMZF, DB71/SMZB, RB/SMZB were investigated. The models of pseudo-first order and pseudo-second order were applied to the experimental data for the study the adsorption kinetics. The model of pseudo-second order was the one that best described the adsorption of all dye/organomodified-zeolites systems. The equilibrium adsorption was analyzed from four models isotherm, namely: Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-B). The results show that the model Freundlich and Langmuir best described the experimental data systems DB71/SMZF and DB71/SMZB, respectively. For systems with RB, the model D-R was the best fit for both adsorbents (SMZF and SMZB). The factorial design 24 was applied to the analysis of the following factors influencing the adsorption process: initial concentration of dye (Co), pH, amount of adsorbent (M) and temperature (T). Under the conditions studied it concludes with the confidence interval of 95%, which for the DB71/SMZF system, the factors and their interactions that influence more were C0, M, pH, pH*M, pH*C0, M*C0, pH*M*C0, in that order. In DB71/SMZB system, the order of influence was: M, C0, pH, pH*M, pH*C0, M*C0, pH*M*C0. For RB/SMZF and RB/SMZB systems, the results were: M, C0, M*C0, pH, pH*M and M, C0, M*C0, respectively. The adsorption equilibrium was attained in about 40 min for all samples. The DB71 removal percentages were in the range of 50 80% and 20 50% for ZML and ZMP, respectively. The range of RB removal percentages varied between 60 80% and 30 50% for ZML and ZMP, respectively.

The alkylation of benzene with ethane was studied at 370 oC over two Pt-containing ZSM-5 catalysts with SiO2/Al2O3 ratios of 30 and 80. While the benzene and ethane conversion decreased with time-on-stream for the PtH-ZSM-5(30) catalyst, the PtH-ZSM-5(80) catalyst demonstrated a stable performance. The deactivation of the PtH-ZSM-5(30) catalyst was found to be more significant, when compared to the PtH-ZSM-5(80) catalyst as a result of differences in the formation of coke. Results from gas sorption and x-ray diffraction experiments showed that coke is preferentially formed within the channel segments of the PtH-ZSM-5(30) catalyst as opposed to coke deposition on the outside surface of the PtH-ZSM-5(80) crystallites, subsequently blocking entrance to the zeolite channels. <br /> The location of the coke deposition was found to affect the product selectivity of the two PtH-ZSM-5 catalysts. The accessibility functions, derived from nitrogen and argon sorption data, suggested that, with prolonged time-on-stream, the coke molecules build up from the middle of the zeolite crystallites outwards towards the surface, as the reaction was carried out over the PtH-ZSM-5(30) catalyst. Partial blockage of the internal pore structure of the PtH-ZSM-5(30) catalyst decreased the diffusion length within the crystallites. In contrast to the typical effect of coking, where the selectivity of para- isomers would be enhanced with coke deposition, the effect of the reduction in the diffusion length of the PtH-ZSM-5(30) crystallites is consistent with the decreasing para-selectivity of the diethylbenzene (DEB) isomers with time-on-stream. <br /> n investigation of the causes of coke locations was conducted, and the results suggested that, the spatial distribution of Pt metal was responsible for the different locations of coke observed. Surface reactions initiated coking in the intercrystalline region of the PtH-ZSM-5(80) catalyst, as the Pt particles on the surface of the PtH-ZSM-5(80) crystallites increased the difficulty of access for reactants to the interior of the crystallites. Within the PtH-ZSM-5(30) catalyst, ethane dehydrogenation and benzene alkylation took place in the micropore network as a result of preferential intracrystalline deposition of Pt metal. Further conversions on the active sites within the PtH-ZSM-5(30) crystallites thus lead intracrystalline coking.

Tertiary butyl alcohol (TBA) is used as a fuel oxygenate and is the main breakdown component of methyl tert butyl ether (MTBE). As such, TBA is found in water systems through storage leaks and spills, presence of MTBE in the water, and as an impure byproduct of MTBE-blended fuels. It presents several health hazards and is a suspected carcinogen. Studies involving aquatic life, mice and rats indicate that TBA is a concern at low concentrations. Wastewater removal of tert butyl alcohol (TBA) has been limited to methodology used by MTBE or by anaerobic or aerobic methods. Neither set of techniques is applicable to TBA due to its long biological degradation period, its very specific conditions for anerobic or aerobic treatment, and its low Henry's law constant, low transformation rate, and its high mobility. The main goal of this project was to determine the adsorption capabilities of different zeolites for TBA. A comparison to previous work done with powdered zeolites and MTBE is shown in the following Chapters. Batch systems of TBA and several different zeolites were examined to determine the best zeolites for TBA adsorption. As shown in Chapter 3, the best zeolites for TBA adsorption over an equilibrium time of 48 hours were silicalite and HiSiv 3000 pellets. Using the two chosen zeolites, silicalite and HiSiv 3000, adsorption isotherms were created and compared against MTBE data using the same data. The final portion of this project included a continuous system consisting of a zeolite column and a steady flow rate of TBA. The zeolite columns consisted of sole silicalite, sole HiSiv 3000, and different proportions of the two zeolites in the same column. All column experiments were run at similar conditions with variation in the adsorbent bed lengths for easy comparison between the resulting breakthrough curves. At the 3-cm bed length, the zeolite columns outperformed the activated carbon column; however, there was no distinct difference between the zeolite columns. In the 6-cm bed length experiments, there were apparent differences between the two zeolite breakthrough curves. The 9-cm column did not differentiate between the zeolites.

Trichloroethylene (TCE) is one of the most common groundwater pollutants in the United States. The EPA estimated that between 9% and 34% of the drinking water sources in the United States may contain TCE. The United States Environmental Protection Agency set a maximum contaminant level at 5 µg/L of trichloroethylene for drinking water. This study investigated the feasibility of removing TCE from water by sorption to ZSM-5 and advanced oxidation to destroy the TCE on the zeolite. Aqueous oxidation of TCE with Fenton's reagent was shown to be efficient for the destruction of TCE. The quantified by-products were cis-DCE and trans-DCE. ZSM-5 rapidly removed TCE from water. A Freundlich isotherm was created for the uptake of TCE by ZSM-5. Once TCE was sorbed to ZSM-5, preliminary experiments showed that the oxidation was able to destroy the TCE while producing the same by-products.

Sustainable energy management has become a high priority for many countries. A great majority of our energy stocks comes from non-renewable fossil fuels, which are currently dwindling. Biofuels are one of the most promising solutions being researched to address this urgent problem. In particular, using transesterified Jatropha curcas L. oil appears to be a promising method of producing biofuels due to several properties of the plant, such as the high oil yield of its seeds and the fact that it does not compete with food crops. The literature mentions many attempts of using zeolites as solid acid catalysts in transesterification reactions of vegetable oils with high free fatty acid (FFA) content. The acid catalysis prevents soap formation and emulsification, which can be observed in the basic process. The use of a solid catalyst makes the separation and purification of the final products steps easier to implement in comparison to catalysis in homogeneous conditions. However, the efficiency of the zeolite in the heterogeneous transesterification reaction of vegetable oil is not well-known yet and varies on the structure of the catalyst used. This project aims at better understanding the relationship between the type of zeolite used and the yield of this particular reaction using reconstituted Jatropha oil from Sesame seed oil, which has a similar composition. Five different types of zeolites were compared: Y, X, Beta, Mordenite & ZSM-5. Non-catalyzed reactions as well as homogeneously catalyzed - with H2SO4 - reactions were also implemented. Since we take advantage of the catalytic properties of different zeolites, the one that were not already in hydrogen form were ion-exchanged and the ion-exchanged species were then analyzed by Energy-Dispersive X-Ray spectroscopy (EDX). Three alcohol-to-oil ratios were tested at atmospheric pressure and at T=115°C for each catalyst in order to determine the influence of this ratio. All experiments were conducted in an airtight autoclave with butan-1-ol in order to obtain a biofuel whose cetane index is higher than regular petroleum-based diesels.

Benzene, toluene, and xylene are three basic raw materials for the production of most aromatic derivatives such as polyesters, plastics and detergents. Xylenes (p-, m- and o-) have the greatest market demand with an increasing annual rate of 6%. Owing to the availability of surplus toluene and low value of C9 aromatics, the transalkylation process is aimed at the production of more valued products, such as xylenes. Catalyst deactivation is a key challenge in transalkylation process. Using industrially relevant operating parameters, the transalkylation of 1,2,4-trimethylbenzene (TMB) with toluene was studied. The effect of zeolite structure and acidity, increased reaction pressure and temperature, and very low levels of platinum (Pt) impregnation has been investigated over both H-form and Pt-loaded zeolites: Beta, Mordenite (MOR), and Y. A fixed bed reactor was used at WHSV of 5 h-1, 400 oC, and a 50:50 wt. % toluene:TMB ratio with the order of activity after 50 h time-on-stream (TOS) of Y > Beta >> MOR at 1 bar. At elevated pressure (10 bar), all catalysts showed better performance with significant improvement in MOR as pore blockage was reduced and the order of activity was Beta > MOR > Y. With varying the Si/Al ratio for zeolites Beta (Si/Al = 12.5, 75 and 150) and Y (Si/Al = 2.6, 6, 15 and 30), the highest stability and xylenes yield were achieved over zeolite Beta with lowest Si/Al ratio at 41 wt. % conversion and 25 wt. % xylenes yield. In contrast, zeolites Y with Si/Al ratio of 2.6 showed the highest deactivation rate, whereas over Y zeolites with Si/Al = 6-30, the conversion was between 25-30 wt. % and xylenes yield around 11 wt. % after 50 h TOS. Incorporation of Pt (0.08 wt. %) further improved the activity of all catalysts with the highest conversion after 50 h TOS over Beta (62 wt. %) where Beta and MOR yielded similar levels of xylenes (40 wt. %). All catalysts were further optimized by reducing Pt levels whilst maintaining the desired stability and highest xylenes yield. In order to further develop a cost-effective and eco-friendly catalyst, the addition of alumina binder to Pt-Beta and the possibility of simplified regeneration of Beta/Pt-Beta catalyst were investigated. Firstly, the alumina binder reduced the conversion and xylenes yield, however, this reduction was small up to 40 wt. % added alumina binder (where xylenes yield only dropped to 35 wt. %). Secondly, the regeneration process was carried out using H2 only and up to four cycles (30 h TOS per cycle). The Pt-Beta catalyst found to be stable and the activity was fully restored by a hydrogenation process at 500 oC. However, the activity of Beta dropped gradually after each cycle suggesting that the H2 alone at 500 oC was insufficient in removing coke precursors. The drop in activity was attributed to the disappearance of Brà ̧nsted acid sites over the spent Beta catalyst due to the growth of coke molecules trapped in cavities leading to highly polyaromatic molecules blocking those active sites.

Thin nanoporous films are attractive for many potential uses for example gas separation, catalysis, filtration of viruses, ore flotation, or as low-dielectric-constant materials. Zeolite and mesoporous materials are the two important nanoporous material classes. In this thesis, we synthesized and characterized two different thin nanoporous films; (i) mesostructured films at the mica-solution interface; (ii) mechanical exfoliated zeolites. The mesoporous materials are well-defined pore shoe and size, and exhibit various morphologies, such as thin films, etc. In contrast, zeolites are a kind of perfect crystal and the morphologies are strongly related to their structures and are difficult to control. Therefore, first we synthesis mesostructured films at mica-solution interface in acidic solution. In-situ Atomic Force Microscopy (AFM) has been used to reveal the formation process of organic and inorganic mesophase films at the molecular level. Then, we synthesized two-dimensional zeolite structures via mechanical exfoliation process that does not involve any chemical intervention and can be applicable to a wide variety of structures with different chemical makeup. Three different zeolite structure nanosheets related to the structure code MWW, UTL, and MFI have been prepared. AFM and TEM have been used to characterized the exfoliated single nanosheet. In order to broaden the application of the single zeolite nanosheet, platinum nano-clusters are encapsulated within mechanical exfoliated zeolite MFI nanosheets by ion exchange from aqueous solution of [Pt(NH3)4](NO3)2. High-angle annular dark field scanning transmission electron microscopy has been used to indicate the Pt clusters in the zeolite MFI structures. Because of the property of the mechanically as-synthesised exfoliated MFI nanosheets that is the long hydrocarbon chains are essentially intact on both sides of the inorganic layer, and can prevent thickening of the zeolite MFI nanosheets along b-axis, we use the mechanically exfoliated MFI as seeds for further growth to form large scale MFI membrane with uniform nano-thickness. Encapsulating noble metals within the channels or cavities of zeolites has already drawn numerous attentions because the well-defined zeolite structure is able to constrain the metal nanoparticle (NPs) aggregation size and enhance the diversity and activity for catalysis. We use the organic surfactant (C22-6-6Br2) and [Pt(NH3)4](NO3)2 as the structure and metal precursor to form Pt-containing nanowires; and use F- to inhibit the premature precipitation of Pt precursors. After involving F-, the Pt-containing nanowire structures were generated.

A combustão do carvão para a produção de energia elétrica tem como consequência a geração de cinzas, que é um dos maiores resíduos gerados no Brasil, em termos de volume (4.109 dm³/ano). Visando a minimização do impacto ambiental causado pelo mau descarte das cinzas, este trabalho teve como objetivo sintetizar e caracterizar zeólitas obtidas a partir de cinza de carvão e aplicar na agricultura como fertilizante potássico. Para isso a cinza utilizada foi obtida no combustor piloto de leito fluidizado operando com carvão da Mina do Leão/RS e empregada para sintetizar material zeolítico a partir do tratamento hidrotérmico alcalino. Foram realizados ensaios experimentais utilizando razão solução/cinzas constante em 6 L mg-1, variando a concentração de hidróxido de potássio (KOH) entre 3 e 5 M, a temperatura entre 100 e 150 ºC e o tempo de reação entre 24 e 72 h. O material sintetizado e a cinza foram caracterizados quanto a sua composição química, mineralógica, morfologia, área superficial específica e capacidade de troca catiônica. Através da caracterização foi observada a formação de duas fases zeolíticas, a chabazita-K e a merlinoíta. A partir da caracterização do material, foi escolhido um dos produtos zeolíticos obtidos para aplicação em solo, como fertilizante de potássio para o cultivo de trigo (Triticum aestivum L.). A condição experimental escolhida foi de 5 M a concentração da solução de KOH, temperatura de 150 ºC e tempo de reação de 24 h. Nesta condição obteve-se apenas uma fase zeolítica identificada, a zeólita merlinoíta, com uma área superficial de 23,37 m² g e uma capacidade de troca catiônica (CTC) de 2,62 meq g 1. Para fins de comparação foi utilizado o fertilizante comercial, cloreto de potássio (KCl), que contém em torno de 60 % de K2O. Foram realizados 35 ensaios experimentais em casa de vegetação da EMBRAPA, utilizando 7 tratamentos (3 doses diferentes de KCl e zeólita 50, 100 e 150 % da dose máxima recomendada e o solo não tratado (testemunha)) em 5 blocos aleatórios. Os experimentos na casa de vegetação foram concluídos com 59 dias de cultivo de trigo e submetidos às análises como determinação da produção de matéria seca da parte aérea e raízes das plantas e análise química do solo e tecido foliar. Verificou-se que a zeólita merlinoíta obtida a partir da cinza de carvão pode ser utilizada como fertilizante, pois teve um desempenho similar ao KCl no crescimento do trigo, não inibindo seu crescimento. Utilizando o tratamento com zeólita 100 % a produção de matéria seca da parte aérea foi de 1,07 ± 0,09 g e raízes 1,6 ± 0,23 g e na análise do tecido foliar teve uma absorção de 3,39 ± 0,31. / Coal combustion for electricity production results in the generation of ash, which is one of the main waste generated in Brazil in terms of volume. Intending the minimization of the environmental impact caused by poor disposal of ashes, this study aimed to synthesize and characterize zeolites obtained from coal ash and apply in agriculture as potassium fertilizer. For this purpose, coal fly ash was obtained from a fluidized bed pilot combustor operating with coal from Mina do Leão/RS and used to synthesize zeolitic material through the alkaline hydrothermal treatment. Experimental tests were performed using the ratio volume of solution/mass of coal fly ash constant at 6 mL mg -1, varying the concentration of potassium hydroxide (KOH) between 3 and 5 M, temperature between 100 and 150 °C and reaction time between 24 and 72 h. The synthesized and coal fly ash material was characterized by their chemical composition, mineralogy, morphology, specific surface area and cation exchange capacity. With the characterization, it was observed the formation of two phases zeolite K-chabazite and merlinoite. By the characterization of the material, it was chosen one of the zeolitic products obtained for application to soil as a potassium fertilizer for the cultivation of wheat (Triticum aestivum L.). The chosen experimental condition was 5 M KOH solution, temperature of 150 °C and 24 h time of reaction. At this condition, only one zeolitic phase was identified, zeolite merlinoite, with a surface area of 23.37 m² g a cation exchange capacity (CEC) of 2.62 meq g-1. For purposes of comparison, the tests in the soil were performed using also a commercial fertilizer, potassium chloride (KCl), containing about 60 % of K2O. A total of 35 experimental trials were carried out in a greenhouse at EMBRAPA, using 7 treatments in 5 random blocks: 50, 100 and 150 % of the maximum recommended dose for KCl and for zeolite and untreated soil (witness). The experiments in the greenhouse were concluded with 59 days of wheat cultivation. The plants were submitted to analysis for dry matter in aerial parts and roots determination. Likewise, soil and foliar tissue were submitted to chemical analysis. It was found that the zeolite Merlinoite obtained from the coal fly ash can be used as a fertilizer because it had a similar performance to KCl in the wheat growth. The treatment with 100% zeolite presented a dry matter production of 1.07 ± 0.09 g for aerial parts and 1.6 ± 0.23 g for roots. Also, the leaf tissue analysis showed a potassium absorption of 3.39 ± 0.31 % m/m in this treatment.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / CO2 à o principal GÃs de Efeito Estufa (GEE), que pode causar consequÃncias indesejÃveis ao meio ambiente, como o aquecimento global. Hà muitas opÃÃes para a separaÃÃo de CO2, entre as quais a adsorÃÃo em materiais porosos à destaque neste trabalho. Carbonos ativados e zeÃlitos tÃm sido propostas como potenciais materiais adsorventes, devido à sua afinidade natural com o CO2 e para a possibilidade de adaptar as propriedades texturais e quÃmica de superfÃcie para aumentar a capacidade e seletividade em cenÃrios de captura especÃficos. Esta tese se concentra em modificar a quÃmica da superfÃcie de adsorventes convencionais, por meio de impregnaÃÃo de amina e troca-iÃnica, de modo a avaliar o efeito de tais modificaÃÃes sobre o seu desempenho de captura de CO2. A secÃÃo experimental foi dividida em trÃs estudos distintos. Inicialmente, isotermas de adsorÃÃo de CO2 foram obtidos em zeÃlito X funcionalizado com concentraÃÃes crescentes de 2-aminoetanol (Monoetanolamina, MEA). Subsequentemente, o carbono ativado, foi investigado como um suporte para a impregnaÃÃo de amina para a captura de CO2. Por Ãltimo, um estudo de troca iÃnica em zeÃlito X foi realizada a fim de investigar a influÃncia de diferentes cÃtions de compensaÃÃo na captura de CO2. Em geral, MEA impregnaÃÃo conduziu a uma deterioraÃÃo nas propriedades texturais dos adsorventes estudados, que sÃo essencialmente microporosos. Quanto maior a concentraÃÃo da soluÃÃo de impregnaÃÃo aumenta, maior à o preenchimento dos microporos por aminas. Hà evidÃncias experimentais de que parte da amina carregada liga covalentemente à estrutura zeolÃtica. A capacidade de adsorÃÃo de CO2 à sempre menor para amostras impregnadas do que para o suporte puro a 298 K, contudo em temperatura maiores, 348 K, à possÃvel observar melhorias. ZeÃlito X mantÃm textura e estrutura cristalina intacta nas amostras de troca-iÃnica. AdsorÃÃo de CO2 à reforÃada por cÃtions de compensaÃÃo menores e mais leves, como LÃtio, atingindo 4,82 mmol/g a 348 K e 1 bar. Em termos de capacidade de trabalho (entre 0,1 e 1 bar) a 298 K, o Ba em zeÃlito X tem um desempenho melhor do que os outros sÃlidos. Ele continua a ser estudado em trabalhos futuros a CO2/N2 e CO2/CH4 seletividade de tais materiais em condiÃÃes secas e Ãmidas. / CO2 à o principal GÃs de Efeito Estufa (GEE), que pode causar consequÃncias indesejÃveis ao meio ambiente, como o aquecimento global. Hà muitas opÃÃes para a separaÃÃo de CO2, entre as quais a adsorÃÃo em materiais porosos à destaque neste trabalho. Carbonos ativados e zeÃlitos tÃm sido propostas como potenciais materiais adsorventes, devido à sua afinidade natural com o CO2 e para a possibilidade de adaptar as propriedades texturais e quÃmica de superfÃcie para aumentar a capacidade e seletividade em cenÃrios de captura especÃficos. Esta tese se concentra em modificar a quÃmica da superfÃcie de adsorventes convencionais, por meio de impregnaÃÃo de amina e troca-iÃnica, de modo a avaliar o efeito de tais modificaÃÃes sobre o seu desempenho de captura de CO2. A secÃÃo experimental foi dividida em trÃs estudos distintos. Inicialmente, isotermas de adsorÃÃo de CO2 foram obtidos em zeÃlito X funcionalizado com concentraÃÃes crescentes de 2-aminoetanol (Monoetanolamina, MEA). Subsequentemente, o carbono ativado, foi investigado como um suporte para a impregnaÃÃo de amina para a captura de CO2. Por Ãltimo, um estudo de troca iÃnica em zeÃlito X foi realizada a fim de investigar a influÃncia de diferentes cÃtions de compensaÃÃo na captura de CO2. Em geral, MEA impregnaÃÃo conduziu a uma deterioraÃÃo nas propriedades texturais dos adsorventes estudados, que sÃo essencialmente microporosos. Quanto maior a concentraÃÃo da soluÃÃo de impregnaÃÃo aumenta, maior à o preenchimento dos microporos por aminas. Hà evidÃncias experimentais de que parte da amina carregada liga covalentemente à estrutura zeolÃtica. A capacidade de adsorÃÃo de CO2 à sempre menor para amostras impregnadas do que para o suporte puro a 298 K, contudo em temperatura maiores, 348 K, à possÃvel observar melhorias. ZeÃlito X mantÃm textura e estrutura cristalina intacta nas amostras de troca-iÃnica. AdsorÃÃo de CO2 à reforÃada por cÃtions de compensaÃÃo menores e mais leves, como LÃtio, atingindo 4,82 mmol/g a 348 K e 1 bar. Em termos de capacidade de trabalho (entre 0,1 e 1 bar) a 298 K, o Ba em zeÃlito X tem um desempenho melhor do que os outros sÃlidos. Ele continua a ser estudado em trabalhos futuros a CO2/N2 e CO2/CH4 seletividade de tais materiais em condiÃÃes secas e Ãmidas.

Zeólitas tipo Y contendo terras raras, RE,Ca/NaY (RE = La, Ce, Nd, Eu, Gd), foram preparadas a partir da forma NaY (razão Si/Al = 2,4 ) por trocas iônicas sucessivas com soluções de cloreto de cálcio e cloreto de terras raras, -através de refluxo; e subseqüente filtragem a vácuo, secagem e tratamento térmico sob fluxo de nitrogênio. Após o tratamento térmico, os Íons aquosos trivalentes de terras raras sofrem hidrólise, formando hidroxilas catiônicas do tipo [RE. OH]2+ e prótons H+, tornando-se localizados nas cavidades e canais da zeólita. O próton reage com o oxigênio da rede cristalina, originando centros ácidos muito fortes. O tipo específico de terra rara trocado ionicamente influencia a acidez total, força e distribuição dos sítios ativos na zeólita. As composições químicas das celas unitárias das amostras foram determinadas por espectrometria de emissão atômica por plasma de argônio induzido (ICP-AES). A cristalinidade, após troca iônica e tratamento térmico, foi confirmada por espectroscopia na região do infravermelho (FT-IR) e difração de raios-X. A microssimetria do íon európio na zeólita Eu,Ca/NaY foi investigada por espectroscopia eletrônica de emissão na região do visível, sob excitação de radiação ultravioleta (396 nm). As propriedades ácidas das amostras RE, Ca/NaY foram estudadas por termogravimetria (TG) e calorimetria exploratória diferencial (DSC), usando n-butilamina como molécula sonda. Por TG, foi investigada a acidez total das amostras; enquanto que por DSC, utilizando o modelo cinético de Borchardt & Daniels, foi investigada a força ácida relativa das amostras. A presença dos centros ácidos de Brönsted e Lewis foi determinada por espectroscopia na região do infravermelho (1700-1300 cm-1) , usando piridina como molécula sonda. A atividade catalítica e seletividade das amostras foram avaliadas na reação química modelo de alquilação de benzeno com a olefina linear 1-dodeceno para formação de alquilbenzeno linear. A reação foi estudada na fase líquida, em um microrreator de batelada, à temperatura de 80°C. 0s produtos monoalquilados e os isômeros lineares de 1-dodeceno foram determinados por cromatografia em fase gasosa e espectrometria de massa (GC-MS). / The Y zeolites containing calcium and rare earth polivalent cations, RE,Ca/NaY (RE = La, Ce, Nd, Eu, Gd), were prepared by ion exchange, refluxing the NaY zeolite (Si/Al = 2,4) with calcium chloride and rare earth chloride solutions, followed by thermal treatment under nitrogen flow. The trivalent hydrated rare earth ions undergo hydrolysis, forming [RE.OH]2+ cation hydroxyls and protons H+, which react with oxygen in the lattice, generating strong acid sites. The rare earth elements influence the total acidity, strength and distribution of the active sites in the zeolite. The unit cell chemical compositions of the samples were determined by Inductively Coupled Plasma / Atomic Emission spectroscopy (ICP/AES). The crystallinity was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray diffraction. The europium microsimetry in the Eu,Ca/NaY zeolite was investigated by emission electronic spectroscopy in the visible region, under ultra-violet excitation (396 nm). The acid properties of the RE,Ca/NaY samples were studied by Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC), using n-butilamine as molecular probe. From TG curves, the total acidity was calculated, whereas the relative acid strength was determinated by DSC curves, using the Borchardt-Daniels kinetic model. The nature of Brönsted and Lewis acid sites was investigated by FT-IR, in the 1700 - 1300 cm-1 region, using pyridine as molecular probe. The catalytic activity and selectivity of the samples were evaluated on the alkylation of benzene with 1-dodecene model reaction, to form linear alkylbenzenes, in liquid phase, at 80°C using a bath reactor. The reactant conversion, extent of isomerization and product distribution were monitored by Gas Chromatography and Mass Spectrometry techniques (GC-MS).