Made available in DSpace on 2014-07-29T15:12:42Z (GMT). No. of bitstreams: 1 Dissertacao Karina Vitti Klein.pdf: 68159 bytes, checksum: 393c40f7ec373b1126ad7cc6bebd1e9e (MD5) Previous issue date: 2008-05-14 / The new family mesoporosas molecular sieves, known as M41S, have been very studied since its discovery in 1992, with bigger prominence for MCM-41, that had its mesoporosa structure that allows ample applications in catalytic processes. In this work were studied two reactions conditions of preparation of the MCM-41 and three forms of nickel incorporation. In the synthesis of the MCM-41 the hidrotérmico treatment and in conditions was used surrounding, while in the incorporation, was used to impregnation of ions nickel and nanopartículas of nickel oxide, as well as the direct synthesis where the nickel was introduced in the structure of the MCM-41, during the synthesis. The gotten materials had been characterized by elementary nickel analysis, X-ray diffraction, nitrogen adsorption/desorption, FT-IR spectra, thermogravimetric analysis, thermoprogrammed reduction. The characterizations had indicated that it had the formation of the mesoporosa structure with periodic pore system, typical of the MCM-41, in both methods of synthesis, being able to be evidenced the biggest viability of the synthesis of the MCM-41 in the surrounding conditions. It can also be verified that it had nickel incorporation in all samples, independent of as this element was inserted. The introduced samples that had had nickel during the synthesis had presented greater excessively average diameter of pores in relation. After the characterization, the samples with nickel had been tested as in the reaction of conversion of carbon monoxide the high temperatures catalytic, known as HTS reaction, presenting activity. / As peneiras moleculares mesoporosas da família M41S têm sido muito estudadas desde sua descoberta em 1992, com maior destaque para MCM-41, devido sua estrutura mesoporosa que permite amplas aplicações em processos catalíticos. Neste trabalho estudou-se duas condições reacionais de preparação da MCM-41 e três formas de incorporação de níquel. Na síntese da MCM-41 utilizou-se o tratamento hidrotérmico e em condições ambiente, enquanto na incorporação, utilizou-se a impregnação de íons níquel e nanopartículas de óxido de níquel, assim como a síntese direta onde o níquel foi introduzido na estrutura da MCM-41, durante a síntese. Os materiais obtidos foram caracterizados por análise elementar de níquel, difração de raios X, análise de área superficial específica e porosidade, espectroscopia na região do infravermelho, análise termogravimétrica, redução termoprogramada. As caracterizações indicaram que houve a formação da estrutura mesoporosa com canais hexagonais unidirecionais, típica da MCM-41, em ambos os métodos de síntese, podendo ser constatado a maior viabilidade da síntese da MCM-41 nas condições ambientes. Pode-se verificar também que houve incorporação de níquel em todas as amostras, independente de como foi inserido. As amostras que tiveram níquel introduzido durante a síntese apresentaram maior diâmetro médio de poros em relação às demais. Posteriormente à caracterização, as amostras com níquel foram testadas como catalisadores na reação de conversão de monóxido de carbono com vapor d água para obtenção de gás hidrogênio a altas temperaturas, conhecida como a reação de HTS, apresentando atividade.

Orientador: Gustavo Paim Valença / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T11:37:38Z (GMT). No. of bitstreams: 1 Vesga_PabloMiguelCoha_M.pdf: 3148003 bytes, checksum: e990cb6467a80b515b813438a624fd7d (MD5) Previous issue date: 2013 / Resumo: Reações de desidrogenação e desidratação no etanol são de grande interesse, já que levam à produção de compostos que são utilizados na indústria química, farmacêutica e cosmética. No presente trabalho, catalisadores de magnésio e molibdênio suportados na peneira molecular MCM-41 foram utilizados no estudo das reações de desidrogenação e desidratação de etanol. Os catalisadores foram preparados através da impregnação por umidade incipiente de nitrato de magnésio e heptamolibdato de amônia, com teores de 0,5% a 2,0% em massa para o magnésio e de 3,0% para o molibdênio. O Mg após a impregnação se apresentou como óxido de Mg e o Mo como óxido de Mo ou carbeto de Mo. Os materiais foram secados, calcinados e caracterizados através de Microscopia Eletrônica de Varredura (MEV), Energia Dispersiva de Raios-X (EDS), Difração de Raios X (DRX), Adsorção Física de Nitrogênio, Análise Infravermelho, Análise Termogravimétrica (TGA). Depois de calcinados, os catalisadores foram carregados no reator, pré-tratados e então testados nas reações de conversão de etanol entre 200 °C e 300 °C. Os produtos da reação foram analisados por cromatografia gasosa (CG). Houve produção de metano, propano, propeno, acetaldeído, éter etílico, 1,3-butadieno, acetato de etila, etano e eteno. A pressão parcial do etanol foi mantida fixa em 7870 Pa. A temperatura que mais favoreceu a reação foi 300 °C e o catalisador que apresentou maior conversão foi aquele possuía 0,5% de Mg e 3,0% de Mo, este último metal na forma de carbeto de Mo. Dos catalisadores testados, os que apresentaram maiores atividades catalíticas foram os que possuíam menor porcentagem de Mg devido a algumas propriedades como maior área superficial. Os catalisadores que possuíam carbeto de Mo favoreceram mais as reações que aqueles que tinham óxido de molibdênio, demonstrando mais uma vez que é um excelente composto para ser usado em reações, especialmente de desidrogenação / Abstract: Dehydrogenation and dehydration reactions with ethanol are interesting, because of these processes produce compounds that are highly used in the chemical, pharmaceutical, cosmetic and biological industries. At present, MCM-41 catalysts impregnated with magnesium and molybdenum are used to study ethanol dehydration and dehydrogenation reactions. The catalysts were prepared by impregnating magnesium nitrate and ammonium heptamolibdate in the silica supports, with a theoretical metal content of 0,5% to 2,0% for magnesium and 3,0% for molybdenum; the Mg was used in oxide form while the Mo was in oxide and carbide form. The solids were dried, calcinated and characterized by Scanning Electron Microscopy (SEM), EDS Analysis, X-Ray Diffraction (XRD), Nitrogen Adsorption, Thermo-Gravimetric Analysis (TGA), Infra-red Analysis (FT-IR). After calcination, the catalyst was loaded into the reactor to undergo pretreatment before being tested in ethanol reactions at low temperatures (473 - 573 K). The gases products of reaction were analyzed by Gas Chromatography (GC). The products were methane, propane, propeno, acetaldehyde, ether ethylic, 1,3-butadiene, ethyl acetate, ethane and ethylene. The partial pressure of ethanol was always the same and maintained at 7870 Pa. The optimal temperature for the reaction was found to be 573 K and the catalyst that had the biggest conversion of ethanol was MCM-41 with 0,5% Mg and 3,0% Mo, with the Mo in carbide form. Of the catalysts tested, those which showed higher catalytic activity were those that had the lowest percentage of Mg due to some properties such as a higher surface area. Catalysts impregnated with Mo carbide had more favorable reactions than those with molybdenum oxide, once again showing that it is an excellent compound for use in reactions, especially dehydrogenation reactions / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

The objective of this work was to evaluate the fundamentals of the currently available CO2 separation technologies and provide a solution for the efficient capture of carbon dioxide from various point source emitting industries. In order to realize a robust approach to advancing the solution to this global issue, the versatility of the process to the range of compounds contained within the stream(s) to be processed must be maintained. It is clear that adsorption, membrane, and aqueous amine based processes are all capable. However, only aqueous amine scrubbing appears economically viable at the current stage of development. In order to challenge this, and potentially drive the separation costs lower, this work centered on hybridizing aqueous amine chemistry and dry adsorption based separations to produce a novel nano-porous material capable of efficient removal of CO2 from flue gas (5% CO2 balance N2 with moisture). In order to combine aqueous amine scrubbing with dry adsorption, a few approaches were considered and evaluated. These included, amine impregnation within the vast pore volume of PE-MCM-41, surface grafting of various amino silane compounds, and finally, a novel approach of volume based amine functionalization (3D grafting). Application of pore-expanded MCM-41 (PE-MCM-41) mesoporous silica coated with 3-[2-(2-aminoethyl-amino)ethylamino]propyltrimethoxysilane (TRI) has been extensively examined for the adsorption of CO2 from N2. A systematic study of the amine loading as a function of the relative amounts of TRI and water used during the grafting procedure, and the temperature of the grafting reaction was carried out. Extremely high levels of active amine content were achieved using prehydrated silica surfaces at grafting temperatures below reflux in order to facilitate thermally controlled water-aided surface polymerization of the aminosilanes. Abstract iii The CO2 adsorption capacities and rates were determined for all materials as a function of the amount of TRI and water per gram of support added to the grafting mixture. The optimal TRI grafted PE-MCM-41 adsorbent exhibited a 2.65 mmol/g adsorption capacity at 25 °C and 1.0 atm for a dry 5% CO2 in N2 feed mixture, which exceeded all literature reported values, for both meso- and microporous materials under the conditions used in this study. Further, the apparent adsorption and desorption rates with the amine functionalized materials were exceedingly high. When considering the grafted amine quantity, the adsorption capacity and rate were found to be mutually dependent on each other, exhibiting an apparent optimal combination. In comparison to zeolite 13X, the optimally loaded TRI-PE-MCM-41 was far superior in terms of dynamic adsorption and desorption performance. These results were further enhanced when the adsorbents were challenged with a humid stream of 5% CO2/N2. The TRIPE-MCM-41 exhibited a 10% increase in CO2 adsorption capacity, whereas the 13X zeolite did not retain any significant CO2 adsorption capacity. The novel concept of an internally variably staged permeator was introduced. A theoretical model was developed and used as the basis for simulation studies. The advantage of the internal variably staged design was shown to permit a very high extent of separation similar to a two stage permeator for purity, while maintaining similar flux rates as per a single stage permeator. This IVSP concept has also taken existing membrane materials and mechanically translated their process performance to a higher level. As such, the unit should prove effective for front end process stream cleanup requirements prior to an adsorption process with the novel TRI-PE-MCM-41 nano-porous adsorbent.

ABSTRACT VANADIUM AND MOLYBDENUM INCORPORATED MCM-41 CATALYSTS FOR SELECTIVE OXIDATION OF ETHANOL G&uuml / &ccedil / bilmez, YeSim Ph.D., Department of Chemical Engineering Supervisor : Prof. Dr. Timur Dogu Co-Supervisor: Prof. Dr. Suna Balci June 2005, 144 pages In this study, V-MCM-41, MCM-41 and Mo-MCM-41 catalysts were synthesized by the one-pot alkaline and acidic synthesis methods. The as-synthesized catalysts were found to have high BET surface areas (430-1450 m2/g), homogeneous pore size distributions (2-4 nm), good crystalline patterns and high metal loading levels (Metal/Si atomic ratio in the solid = 0.01-0.16) as determined by the characterization studies. MCM-41 and Mo-MCM-41 catalysts were highly active in the selective oxidation of ethanol with conversion levels of 56% and 71%, respectively, at 400oC for an O2/EtOH feed ratio of 0.5. Both catalysts had very high selectivities to acetaldehyde at temperatures below 300oC. Conversions exceeded 95% with the V-MCM-41 catalyst having a V/Si molar ratio (in the solid) of 0.04 in the temperature range of 300oC-375oC for the O2/EtOH feed ratios of 0.5-2.0. Acetaldehyde selectivities changed between 0.82-1.00 at the temperature range of 150oC-250oC. Ethylene, which is listed as a minor side product of the selective oxidation of ethanol in literature, was produced with a maximum yield of 0.66 at 400oC at the O2/EtOH feed ratio of 0.5. This yield is higher than the yields obtained in the industrial ethylene production methods such as thermal cracking and oxidative dehydrogenation of ethane. Besides, the feedstock used in this work is a non-petroleum chemical, namely ethanol, which can be produced from sugar and crop wastes by fermentation. Thus, the findings of this study are also proposed as an alternative ethylene production method from a non-petroleum reactant at lower temperatures with higher yields. &Ouml / Z ETANOL&Uuml / N SE&Ccedil / iCi OKSiDASYONUNDA KULLANILMAK &Uuml / ZERE VANADYUM VE MOLiBDEN i&Ccedil / EREN MCM-41 KATALiZ&Ouml / RLERiNiN &Uuml / RETiMi G&uuml / &ccedil / bilmez, YeSim Doktora, Kimya M&uuml / hendisligi B&ouml / l&uuml / m&uuml / Tez Y&ouml / neticisi : Prof. Dr. Timur Dogu Ortak Tez Y&ouml / neticisi: Prof. Dr. Suna Balci Haziran 2005, 144 sayfa Bu &ccedil / aliSma kapsaminda, dogrudan sentez metoduyla, alkali ve asit ortamlarinda, V-MCM-41, MCM-41 ve Mo-MCM-41 kataliz&ouml / rleri sentezlenmiStir. Bu Sekilde sentezlenen kataliz&ouml / rlerin y&uuml / ksek BET y&uuml / zey alanlarina (430-1450 m2/g), homojen g&ouml / zenek boyutu dagilimlarina (2-4 nm), iyi kristal yapilarina ve y&uuml / ksek metal y&uuml / kleme oranlarina (Metal/Si katidaki molar orani =0.01-0.16) sahip olduklari karakterizasyon &ccedil / aliSmalari sonucunda g&ouml / r&uuml / lm&uuml / St&uuml / r. MCM-41 ve Mo-MCM-41 kataliz&ouml / rleri etanol&uuml / n se&ccedil / ici oksidasyonunda, 400oC&amp / #8217 / de ve reakt&ouml / r giriSinde 0.5&amp / #8217 / lik O2/EtOH oraninda, sirasiyla, 56% ve 71% d&ouml / n&uuml / S&uuml / m seviyeleriyle, y&uuml / ksek aktivite g&ouml / stermiSlerdir. Her iki kataliz&ouml / r de 300oC&amp / #8217 / nin altinda &ccedil / ok y&uuml / ksek asetaldehit se&ccedil / iciligi g&ouml / stermiStir. D&ouml / n&uuml / S&uuml / m degerleri, V/Si katidaki molar orani 0.04 olan V-MCM-41 kataliz&ouml / r&uuml / i&ccedil / in / 300oC-375oC araliginda ve 0.5-0.2 O2/EtOH reakt&ouml / r giriSi oranlarinda, 95%&amp / #8217 / i ge&ccedil / miStir. Asetaldehit se&ccedil / icilikleri, 150oC-250oC araliginda, 0.82-1.00 arasinda degiSmiStir. Literat&uuml / rde, etil alkol&uuml / n se&ccedil / ici oksidasyonunda &ouml / nemsiz bir yan &uuml / r&uuml / n olarak s&ouml / z&uuml / ge&ccedil / en etilen, 400oC&amp / #8217 / de ve 0.5&amp / #8217 / lik O2/EtOH reakt&ouml / r giriS oraninda 0.66 maksimum verimle &uuml / retilmiStir. Bu verim degeri isil par&ccedil / alanma ve etanin kismi oksidasyonu gibi end&uuml / striyel etilen &uuml / retim yollariyla elde edilen verimlerden daha y&uuml / ksektir. Ayrica, bu &ccedil / aliSmada kullanilan etanol petrol-bazli olmayan bir hammaddedir ve Seker pancari atiklarindan fermentasyonla &uuml / retilebilmektedir. Bu sebeple, bu &ccedil / aliSmadaki bulgular, petrol-bazli olmayan bir hammaddeden, daha d&uuml / S&uuml / k sicaklikta, daha y&uuml / ksek verimle etilen elde etmek i&ccedil / in alternatif bir &uuml / retim metodu olarak da &ouml / nerilmiStir. Anahtar Kelimeler: Etilen, Etil alkol, Se&ccedil / ici Oksidasyon, MCM-41, V-MCM-41, Mo-MCM-41, Oksidatif Dihidrojenasyon, Kismi Oksidasyon

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-19T16:09:58Z No. of bitstreams: 1 VITÓRIA DE ANDRADE FREIRE - DISSERTAÇÃO PPGEQ 2016..pdf: 2687690 bytes, checksum: 093bc81d91144a15964f2333d08a5c8f (MD5) / Made available in DSpace on 2018-03-19T16:09:58Z (GMT). No. of bitstreams: 1 VITÓRIA DE ANDRADE FREIRE - DISSERTAÇÃO PPGEQ 2016..pdf: 2687690 bytes, checksum: 093bc81d91144a15964f2333d08a5c8f (MD5) Previous issue date: 2016-04-29 / Capes / A pesquisa no desenvolvimento de estruturas do tipo micro-mesoporosas tem por intuito a obtenção de materiais porosos com características superiores, uma vez que busca unir a ácidez elevada da zeólita MCM-22, com o sistema de mesoporos, da peneira molecular MCM-41, consequentemente melhorar a difusão de moléculas volumosas. Nesta pesquisa foram sintetizadas as seguintes estruturas porosas: Inicialmente foi obtido o percussor lamelar MCM22-(P) com razão molar SiO2\Al2O3 = 30 e ativada para obter sua forma zeólítica MCM-22 a 550 0C por 5 horas. Em seguida, foi realizada a síntese do material micro-mesoporoso do tipo MCM-22/MCM-41, tratando 2 g da zeólita MCM-22, com uma solução de 25 mL de brometo de cetiltrimetilamônio (CTABr) a 10 % em massa, onde o material permaneceu em estufa a 1100C por 7 dias. Com o intuito de obter um novo material com melhor organização estrutural, utilizou-se a MCM-22 nas seguintes proporções (5%, 10% e 15%), permanecendo em estufa a 300C por 24 horas, sendo ativado em corrente de ar por 5500C por 5 horas. Os resultados das caracterizações de difratometria de raios-X, evidenciaram a formação do precursor MCM-22 (P) e sua forma zeólítica MCM22, com os picos da topologia MWW. A curvas obtidas por meio da análise termogravimétrica (TG/DrTG), demostraram as perdas de massa da água e demais adsorvatos. As micrografias (MEV), apresentou formato toroidal com depreciamento na região central para a MCM-22. Por meio dos resultados de adsorção física de N2, verifica-se que as zeólitas MCM-22, com isotermas do tipo I e loop de histerese do tipo H4. A partir dos difratogramas de raios - X para os materiais micro-mesoporosos foi possível observar a formação das estruturas porosas, com a identificação dos picos de reflexão pertinentes a fase microporosa da MCM-22 e da peneira molecular MCM-41, coexistindo em uma única fase estrutural. As imagens obtidas por MEV, detectam a formação de aglomerados de partículas da fase mesoporosa sendo constituída em torno da fase microporosa. A análise textural mostraram uma diminuição do volume de microporos e um aumento do volume de mesoporos, com isotermas do tipo IV e histereses 2. Demonstrando assim que as caracterizações foram eficazes na elucidação das estruturas porosas. Foi possível obter os materiais micromesoporosos para ambas as metodologias adotadas, sendo o teor de 5% de zeólita MCM-22 a melhor condição de síntese para obtenção desse novo material. / The research on the development of micro-mesoporous structures has the purpose of obtaining porous materials with superior characteristics, once it seeks to join the high acidity of MCM-22 zeolite with the mesoporous system of MCM41 molecular sieve, consequently improving the diffusion of bulky molecules. In this research, the following porous structures were synthesized: Initially, the MCM-22-(P) lamellar precursor was obtained with molar ratio of SiO2\Al2O3 = 30 and was activated to obtain its MCM-22 zeolite form at 550 °C for 5 hours. Then, MCM-22/MCM-41 micro-mesoporous material was synthesized by treating 2 g of MCM-22 zeolite with a solution of 25 mL of 10% wt cetyltrimethylammonium bromide (CTABr), where the material remained in an incubator at 110 °C for 7 days. In order to obtain a new material with better structural organization, the MCM-22 was used in the following proportions (5%, 10% and 15%), remaining in an incubator at 30 °C for 24 hours, being activated in air stream at 550 °C for 5 hours. The results of the X-ray diffraction characterization demonstrated the MCM-22 (P) precursor formation and its MCM-22 zeolite form, with MWW topology peaks. The curves obtained by means of the thermogravimetric analysis (TG/DrTG), showed the losses of water mass and other adsorbates. The micrographs (SEM) presented toroidal format with depreciation in the central region for MCM-22. By means of the results of physical adsorption of N2, it was verified for MCM-22 zeolites: type I isotherms and hysteresis loops of type-IV. From the X-ray diffractograms for the micro-mesoporous materials, it was possible to observe the formation of the porous structures, with the identification of the reflection peaks pertinent to the microporous phase of MCM-22 and the MCM-41 molecular sieve, coexisting in a single structural phase. The SEM images detected the formation of particle agglomerates of the mesoporous phase being constituted around the microporous phase. The textural analysis showed a decrease in the volume of micropores and an increase in the volume of mesopores, with type IV isotherms and hysteresis loops of type-II. Thus demonstrating that the characterizations were effective in elucidating the porous structures. It was possible to obtain the micro-mesoporous materials for both methodologies, being the 5% content of MCM-22 zeolite the best synthesis condition to obtain this new material.

Made available in DSpace on 2014-12-17T15:41:47Z (GMT). No. of bitstreams: 1 KesiaKV.pdf: 2272602 bytes, checksum: 46f23a52fbc9d4e74dfd9f25d2f58e11 (MD5) Previous issue date: 2009-02-19 / In present work, mesoporous materials of the M41S family were synthesized, which were discovered in the early 90s by researchers from Mobil Oil Corporation, thus allowing new perspectives in the field of catalysis. One of the most important members of this family is the MCM-41, which has a hexagonal array of mesopores with pore diameters ranging from 2 to 10 nm and a high surface area, enabling it to become very promising for the use as a catalyst in the refining of oil in the catalytic cracking process, since the mesopores facilitate the access of large hydrocarbon molecules, thereby increasing the production of light products, that are in high demand in the market. The addition of aluminum in the structure of MCM-41 increases the acidity of the material, making it more beneficial for application in the petrochemical industry. The mesoporous materials MCM-41 and Al-MCM-41 (ratio Si / Al = 50) were synthesized through the hydrothermal method, starting with silica gel, NaOH and distilled water. CTMABr was used as template, for structural guiding. In Al-MCM-41 the same reactants were used, with the adding of pseudoboehmite (as a source of aluminum) in the synthesis gel. The syntheses were carried out over a period of four days with a daily adjustment of pH. The optimum conditions of calcination for the removal of the organic template (CTMABr) were discovered through TG / DTG and also through analysis by XRD, FTIR and Nitrogen Adsorption. It was found that both the method of hydrothermal synthesis and calcination conditions of the studies based on TG were promising for the production of mesoporous materials with a high degree of hexagonal array. The acidic properties of the materials were determined by desorption of n-butylamine via thermogravimetry. One proved that the addition of aluminum in the structure of MCM-41 promoted an increase in the acidity of the catalyst. To check the catalytic activity of these materials, a sample of Atmospheric Residue (RAT) that is derived from atmospheric distillation of oil from the Pole of Guamar?- RN was used. This sample was previously characterized by various techniques such as Thermogravimetry, FTIR and XRF, where through thermal analysis of a comparative study between the thermal degradation of the RAT, the RAT pyrolysis + MCM-41 and RAT + Al- MCM-41. It was found that the Al-MCM-41 was most satisfactory in the promotion of a catalytic effect on the pyrolysis of the RAT, as the cracking of heavy products in the waste occurred at temperatures lower than those observed for the pyrolysis with MCM-41, and thereby also decreasing the energy of activation for the process and increasing the rates of conversion of residue into lighter products / No presente trabalho, foram sintetizados materiais mesoporos da fam?lia M41S que foram descobertos no in?cio dos anos 90 por pesquisadores da Mobil Oil Corporation, possibilitando assim novas perspectivas no ramo da cat?lise. Um dos mais importantes membros desta fam?lia ? o MCM-41, que possui um arranjo hexagonal de mesoporos com di?metros de poros entre 2 a 10 nm e uma alta ?rea superficial, tornando-o bastante promissor para ser utilizado como catalisador no refino do petr?leo para o craqueamento catal?tico, j? que seus mesoporos facilitam o acesso de mol?culas grandes de hidrocarbonetos, aumentando assim a produ??o de produtos leves com uma alta demanda no mercado. A adi??o de alum?nio na estrutura do MCM-41 aumenta a acidez do material, tornando-o mais positivo para aplica??o na ind?stria petroqu?mica. Os materiais mesoporosos do tipo MCM-41 e Al-MCM- 41 (raz?o Si/Al=50) foram sintetizados atrav?s do m?todo hidrot?rmico partindo da S?lica gel, NaOH e ?gua destilada. Como direcionador estrutural foi utilizado CTMABr. Para o Al- MCM-41 utilizaram-se os mesmos reagentes acrescentando a pseudobohemita (fonte de alum?nio) no gel de s?ntese. As s?nteses foram realizadas durante um per?odo de quatro dias com corre??o di?ria de pH. As melhores condi??es de calcina??o para remo??o do direcionador org?nico (CTMABr) foram otimizadas por TG/DTG e atrav?s de an?lises por DRX, FTIR e adsor??o de nitrog?nio verificou-se que tanto o m?todo de s?ntese hidrot?rmica como as condi??es de calcina??o baseado nos estudos por TG foram promissores para produ??o de materiais mesoporosos com alto grau de ordena??o hexagonal. As propriedades ?cidas dos materiais foram determinadas pela dessor??o de n- butilamina via termogravimetria. Comprovou-se que a adi??o de alum?nio na estrutura do MCM-41 promoveu um aumento na acidez deste catalisador. Para verificar a atividade catal?tica desses materiais utilizou-se uma amostra do Res?duo Atmosf?rico (RAT) que ? proveniente da destila??o atmosf?rica do petr?leo proveniente do P?lo de Guamar?- RN previamente caracterizado por v?rias t?cnicas como: Termogravimetria, FTIR e FRX, realizando-se atrav?s da an?lise t?rmica um estudo comparativo entre a degrada??o t?rmica do RAT, pir?lise do RAT+MCM-41 e RAT+Al-MCM-41. Verificou-se que o Al-MCM-41 promoveu um efeito catal?tico mais satisfat?rio na pir?lise do RAT, j? que o craqueamento dos produtos pesados presentes no res?duo ocorreu em temperaturas inferiores ?s observadas para a pir?lise com MCM-41 e com isso diminuindo tamb?m a energia de ativa??o para o processo, bem como aumentando os valores de convers?o do res?duo em produtos leves

A research project was carried out to investigate several aspects of Mobil’s composition of matter #41 (MCM-41) pertaining to its potential application in water treatment technologies. The goal of the work was to lead to a recommendation of whether further work investigating this particular, potential application is warranted at the present time. A dissolution experiment indicated that Pd/MCM-41 is more stable in contact with deionized water at 25±0.1 degrees Celsius than purely siliceous MCM-41. Stability increases with increasing mass percent loading of Pd in the Pd/MCM-41 material. The increased stability was attributed to a reduction in Pd/MCM-41 surface areas relative to the parent MCM-41 material. The reduction in surface area is likely the result of partial or complete blocking of the MCM-41 mesopores by Pd centres. Ni/MCM-41 was less stable in contact with deionized water than MCM-41 and Pd/MCM-41. Both Ni and Pd impregnated MCM-41 exhibited enhanced stability relative to purely siliceous MCM-41 in 0.01 M NaCl solution. The stability enhancement was more pronounced for Pd/MCM-41. A long term dissolution experiment showed that MCM-41 retained its characteristic hexagonal mesopore structure and high surface area after 1,174 days of contact with deionized water. The ability of Pd/MCM-41 to absorb hydrogen was investigated in a series of experiments in pressure cells at 25±0.1 degrees Celsius and approximately 101.3 kPa. The Pd in Pd/MCM-41 was able to absorb 0.85±0.18 moles of hydrogen per mole of Pd present. This was a higher level of absorption than found in most other, published Pd-hydrogen investigations. It is proposed that enhanced uptake of hydrogen by Pd/MCM-41 may be the result of a higher proportion of surface and subsurface sites in the samples relative to other supported Pd materials. Batch and column trichloroethylene (TCE) degradation experiments indicated that Pd/MCM-41 has substantial longevity while degrading at least 91% of inflow TCE concentrations in hydrogen-saturated deionized water over 5,036 pore volumes. The average inflow TCE concentration was 4.94E-2 ± 4.87E-3 mmol/l with maximum and minimum concentrations of 7.24E-2 mmol/l and 2.63E-2 mmol/l, respectively. The dominant breakdown product of TCE degradation in the presence of Pd/MCM-41 was ethane. Minimal concentrations of intermediate degradation products were detected, if at all. This result suggests that TCE completely degrades to ethane before desorbing from the Pd/MCM-41 surface. It was shown that Pd/MCM-41 was more effective and had better longevity at treating inflow TCE compared to a lower cost substitute, Pd/sand. Unlike Pd/MCM-41, Ni/MCM-41 did not induce degradation of TCE. Column experiments using Ni-Pd/MCM-41 materials indicated that while the material does induce degradation of TCE, the Pd cannot be substituted for Ni on a 1:1 basis while still obtaining similar degradation results as Pd/MCM-41. Pd/MCM-41 was not able to substantially reduce initial concentrations of hexamethylphosphoramide (HMPA) in a batch experiment. A small reduction in the initial HMPA concentration was attributed to adsorption onto the Pd/MCM-41 surfaces rather than degradation of the compound. Several of the above-mentioned results suggest that MCM-41 and Pd/MCM-41 show great potential for being incorporated into water treatment technologies. Both the long term stability of the material in contact with deionized water and the longevity of a Pd/MCM-41 column in treating inflow TCE are very promising results with respect to applications in water treatment technologies. It is recommended that future work be pursued with this goal in mind.

Deuteron 1D and 2D NMR spectroscopy was used to study the dynamics of water molecules within the mesoporous material MCM-41. The deuteron spectra show three magnetization components for a sample hydrated to a 0.2 monolayer level. One component was assigned to the pore surface silanol group deuterons that exhibit a broad Gaussian line of 32.6 kHz FWHM and the other components were assigned to the water deuterons. At room temperature one water deuteron component has a powder pattern line shape (splitting of about 4.2 kHz and population of about 61%) and the other has a Lorentzian line shape (about 388 Hz FWHM and population of 39%). Magnetization exchange occurs between these components. An exchange model, based on multi-site exchange, was constructed and used to analyse the results for exchange. For the 0.2 monolayer sample the rate of magnetization exchange out of the hydration site where the water deuterons exhibit a Lorentzian line in the deuteron spectra is 1.3 ms. 2D measurements at 233 K and room temperature confirmed the magnetization exchange scenario for the two water deuteron sites. Combining the deuteron results with proton-silicon cross polarization magic angle spinning experiments together with heat treatment of the sample, definitive hydration site identification for MCM-41 was achieved. This study has shown that the water molecules bound to the hydrogen-bonded silanol groups produce the powder pattern while water molecules bound to the single silanol groups produce the Lorentzian line. This represents a necessary first step toward a meaningful modeling of NMR observables in terms of site-specific water molecule coordination and dynamics in MCM-41.

Deuteron 1D and 2D NMR spectroscopy was used to study the dynamics of water molecules within the mesoporous material MCM-41. The deuteron spectra show three magnetization components for a sample hydrated to a 0.2 monolayer level. One component was assigned to the pore surface silanol group deuterons that exhibit a broad Gaussian line of 32.6 kHz FWHM and the other components were assigned to the water deuterons. At room temperature one water deuteron component has a powder pattern line shape (splitting of about 4.2 kHz and population of about 61%) and the other has a Lorentzian line shape (about 388 Hz FWHM and population of 39%). Magnetization exchange occurs between these components. An exchange model, based on multi-site exchange, was constructed and used to analyse the results for exchange. For the 0.2 monolayer sample the rate of magnetization exchange out of the hydration site where the water deuterons exhibit a Lorentzian line in the deuteron spectra is 1.3 ms. 2D measurements at 233 K and room temperature confirmed the magnetization exchange scenario for the two water deuteron sites. Combining the deuteron results with proton-silicon cross polarization magic angle spinning experiments together with heat treatment of the sample, definitive hydration site identification for MCM-41 was achieved. This study has shown that the water molecules bound to the hydrogen-bonded silanol groups produce the powder pattern while water molecules bound to the single silanol groups produce the Lorentzian line. This represents a necessary first step toward a meaningful modeling of NMR observables in terms of site-specific water molecule coordination and dynamics in MCM-41.

The discovery of MCM-41 materials have attracted substantial research attention due to the remarkable features of these materials including a narrow pore size distribution, high surface area, high pore volume, and high thermal and hydrothermal stability, as well as, parallel hexagonal arrangement of uniform cylindrical pores without pore channel intersection. These well-defined structural characteristics make them ideal media to study the adsorption, catalysis, ion exchange, and separation. MCM-41 sample used in this study was synthesized in (Chemical Engineering Department, Gazi University). The MCM-41 was synthesized by using sodium silicate (0.0705 mol, 27% Silica) as a source of silica and surfactant cetyltrimethylammoniumbromides (CTMABr) (0.036 mol) as template. A characteristic feature of this direct hydothermal synthesis was relatively long synthesis time (96 hour at 120&deg / C). MCM-41 was characterized by using XRD, and nitrogen physisorption analysis techniques. The characteristic peak in the low-angle region corresponding to 2&amp / #952 / = 2.406&deg / was obtained for MCM-41 sample indicating high structural ordering of the MCM-41sample. The BET, surface area was found as (492.2 m /g), with an average pore diameter (25 &Aring / ). In this study the sorption equilibrium of C aromatics (p-xylene, m-xylene, o-xylene, and ethylbenzene ) on MCM-41 at different temperatures (30&deg / C, 50&deg / C, 65&deg / C, 80&deg / C) was investigated by using an automated gravimetric electrobalance system. It was found that the amounts of each sorbate (p-xylene, m-xylene, o-xylene, and ethylbenzene) adsorbed at a given relative pressure on MCM-41 decreased when the temperature of the adsorption isotherms increases. The adsorption isotherms were type V, according to IUPAC isotherm classification due to the mesoporous nature of the MCM-41 sample. The hysteresis are associated with condensation-evaporation within a narrow distribution of mesopores with each adsorption isotherms. It was shown that as the temperature for the adsorption isotherms increases the size of hysteresis decreases for each sorbate. The volume of sorbates (V ) were obtained from the mass uptake at maximum relative pressure by taking the normal liquid density at the adsorption temperature for all sorbates. These values are significantly lower than that obtained from low-temperature nitrogen isotherm. The reason of this difference is that the density of the adsorbed phase is unlikely to be exactly the same as that of the liquid adsorptive and curvature of some isotherms at high relative pressure leads to uncertainty in the location of the upper limit for pore filling.