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Mesoestruturas porosas a partir de materiais naturais / Porous mesostructures from natural materialsSchwanke, Anderson Joel 17 December 2012 (has links)
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Previous issue date: 2012-12-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The MCM-41 mesoporous synthesis was done using rice hulls ash and chrysotile as
natural alternative silica sources. For the using of these sources, chemical and thermic
treatments were done in both materials. After chemical and thermic treatments, these
materials were employed on the MCM-41 mesoctructures synthesis. The natural materials
treated and employed in the synthesis were characterized by several techniques such as X-ray
diffraction, N2 adsorption and desorption, scanning electronic microscopy and
thermogravimetric analysis. MCM-41 standart samples synthetized with aerosil 200
commercial s?lica were used to evaluation. The formed material from rice hulls ash showed
values from BET specific area about 468 m?.g-1, N2 adsorption and desorption isotherms and
loss mass similar to reference materials. The silica from chrysotile calcined and leached was
employed to mesoporous materials synthesis. The BET specific area showed values about 700
m?.g-1, N2 adsorption and desorption isotherms type IV and loss mass similar to mesoporous
materials. The formed material from calcined and leached chrysotile, without calcination,
applied to phenol remotion carried high performance liquid chromatography and evaluated
with organophilic clays with different treatments. By the characterization techniques were
proved that mesoporous materials with lesser order that reference samples. The material
formed from rice hulls ash without the calcination step achieved better adsorption results than
organophilic clays / A s?ntese dos mesoporosos do tipo MCM-41 foram realizadas empregando materiais
naturais como cinza da casca de arroz e crisotila como fontes alternativas de s?lica. Para a
utiliza??o destas fontes, tratamentos t?rmicos e qu?micos foram realizados em ambos os
materiais. Os materiais naturais, ap?s tratamento t?rmico e qu?mico, foram empregados na
forma??o de mesoestruturas do tipo MCM-41. Os materiais naturais, tratados e empregados
na s?ntese foram caracterizados por diversas t?cnicas, como difra??o de raios-X, adsor??o e
dessor??o de N2, microscopia eletr?nica de varredura e an?lise termogravim?trica. Amostras
padr?es de MCM-41 sintetizadas com s?lica comercial pirolisada aerosil 200 foram utilizadas
como crit?rio de compara??o. O material formado a partir da cinza da casca de arroz
calcinada e lixiviada apresentou ?rea espec?fica de 468 m?.g-1, isotermas de adsor??o e
dessor??o de N2 t?picas de materiais mesoporosos e eventos de perda de massa semelhantes a
amostra de refer?ncia. A s?lica derivada da crisotila calcinada e lixiviada foram utilizadas
para a s?ntese de materiais mesoporosos. O material apresentou valores de ?rea espec?fica
BET de 700 m?.g-1, isotermas de adsor??o e dessor??o de N2 do tipo IV e perdas de massa
caracter?sticas de materiais mesoporosos. O material formado a partir da cinza da casca de
arroz, sem a etapa de calcina??o foi aplicado na adsor??o de fenol acompanhado por
cromatografia l?quida de alta efici?ncia (CLAE) e comparado com argilas organof?licas com
diversos tratamentos. Pelas t?cnicas de caracteriza??o comprova-se que os materiais s?o do
possuem menor ordena??o que a amostra de refer?ncia. O material formado a partir da cinza
da casca de arroz, e sem a etapa de calcina??o, obteve melhores resultados de adsor??o de
fenol, se comparado ?s argilas organof?licas
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Prepara??o e caracteriza??o de catalisadores ? base de tit?nio suportado em MCM-41 para produ??o de compostos oxigenados atrav?s da pir?lise catal?tica do capim elefanteFontes, Maria do Socorro Braga 17 May 2013 (has links)
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Previous issue date: 2013-05-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In recent years, the area of advanced materials has been considerably, especially when it comes to materials for industrial use, such as is the case with structured porosity of catalysts suitable for catalytic processes.
The use of catalysts combined with the fast pyrolysis process is an alternative to the oxygenate production of high added value, because, in addition to increasing the yield and quality of products, allows you to manipulate the selectivity to a product of interest, and therefore allows greater control over the characteristics of the final product.
Based on these arguments, in this work were prepared titanium catalysts supported on MCM-41 for use in catalytic pyrolysis of biomass, called elephant grass.
The reactions of pyrolysis of biomass were performed in a micro pyrolyzer, Py-5200, coupled to GC / MS, the company CDS Corporation, headquartered in the United States. The catalysts Ti-MCM-41 in different molar ratios were characterized by XRD, TG / DTG, FT-IR, SEM, XRF, UV-visible adsorption of nitrogen and the distribution of particle diameter and specific surface area measurement by the BET method. From the catalytic tests it was observed that the catalysts synthesized showed good results for the pyrolysis reaction.The main products were obtained a higher yield of aldehydes, ketones and furan. It was observed that the best reactivity is a direct function of the ratio Si/Ti, nature and concentration of the active species on mesoporous supports. Among the catalysts Ti-MCM-41 (molar ratio Si / Ti = 25 and 50), the ratio Si / Ti = 25 (400 ? C and 600 ? C) favored the cracking of oxygenates such as acids , aldehydes, ketones, furans and esters. Already the sample ratio Si / Ti = 50 had the highest yield of aromatic oxygenates / Nos ?ltimos anos, a ?rea de materiais tem avan?ado consideravelmente, principalmente, quando se trata de materiais para uso industrial, como ? o caso de catalisadores estruturados com porosidade adequada para os processos catal?ticos.
O uso de catalisadores combinados ao processo de pir?lise r?pida ? uma alternativa para a produ??o de compostos oxigenados de alto valor agregado, pois, al?m de elevar o rendimento e qualidade dos produtos, permite manipular a seletividade para um produto de interesse e, portanto, permite um maior controle sobre as caracter?sticas do produto final.
Com base nesses argumentos, neste trabalho foram preparados catalisadores de tit?nio suportados em MCM-41 para uso em pir?lise catal?tica da biomassa, denominada de capim elefante.
As rea??es de pir?lise da biomassa foram realizadas em um micro pirolisador, Py-5200, acoplado ao GC/MS, da empresa CDS Corporation, sediada nos Estados Unidos. Os catalisadores Ti-MCM-41, em diferentes raz?es molares, foram caracterizados por DRX, TG/DTG, FT-IR, MEV, FRX, UV-Vis?vel, adsor??o de nitrog?nio, distribui??o de di?metro de part?culas e medidas de ?rea espec?fica pelo m?todo BET.
A partir dos testes catal?ticos foi poss?vel observar que os catalisadores sintetizados apresentaram bons resultados para a rea??o de pir?lise. Entre os catalisadores Ti-MCM-41 (raz?es molares Si/Ti = 25 e 50), o de raz?o Si/Ti=25 (temperatura de 400?C e 600?C) favoreceu o craqueamento de compostos oxigenados, tais como, ?cidos, alde?dos, cetonas, furanos e ?steres. J? a amostra de raz?o Si/Ti = 50 apresentou maior rendimento de arom?ticos oxigenados
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Convers?o t?rmica e termocatal?tica ? baixa temperatura do ?leo de girassol para obten??o de bio-?leoAra?jo, Aruzza Mabel de Morais 01 July 2011 (has links)
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Previous issue date: 2011-07-01 / The use of biofuels remotes to the eighteenth century, when Rudolf Diesel made the first trials using peanut oil as fuel in a compression ignition engine. Based on these trials, there was the need for some chemical change to vegetable oil. Among these chemical transformations, we can mention the cracking and transesterification. This work aims at conducting a study using the thermocatalytic and thermal cracking of sunflower oil, using the Al-MCM-41 catalyst. The material type mesoporous Al-MCM-41 was synthesized and characterized by Hydrothermical methods of X-ray diffraction, scanning electron microscopy, nitrogen adsorption, absorption spectroscopy in the infrared and thermal gravimetric analysis (TG / DTG).The study was conducted on the thermogravimetric behavior of sunflower oil on the mesoporous catalyst cited. Activation energy, conversion, and oil degradation as a function of temperature were estimated based on the integral curves of thermogravimetric analysis and the kinetic method of Vyazovkin. The mesoporous material Al-MCM-41 showed one-dimensional hexagonal formation. The study of the kinetic behavior of sunflower oil with the catalyst showed a lower activation energy against the activation energy of pure sunflower oil. Two liquid fractions of sunflower oil were obtained, both in thermal and thermocatalytic pyrolisis. The first fraction obtained was called bio-oil and the second fraction obtained was called acid fraction. The acid fraction collected, in thermal and thermocatalytic pyrolisis, showed very high level of acidity, which is why it was called acid fraction. The first fraction was collected bio-called because it presented results in the range similar to petroleum diesel / O uso dos biocombust?veis remota ao s?culo XVIII, quando Rudolf Diesel realizou os primeiros ensaios utilizando o ?leo de amendoim como combust?vel em um motor de igni??o por compress?o. Com base nesses ensaios, constatou-se a necessidade de realizar algumas transforma??es qu?micas ao ?leo vegetal. Dentre essas transforma??es qu?micas, pode-se citar a transesterifica??o e o craqueamento. Este trabalho tem como objetivo, realizar um estudo utilizando-se o craqueamento t?rmico e termocatal?tico do ?leo de girassol, utilizando o Al-MCM-41 como catalisador. O material mesoporoso tipo Al-MCM-41 foi sintetizado hidrotermicamente e caracterizado pelos m?todos de difra??o de raios-X, microscopia eletr?nica de varredura, adsor??o de nitrog?nio, espectroscopia de absor??o na regi?o do infravermelho e an?lise termogravim?trica (TG/DTG). Ainda foi realizado o estudo do comportamento termogravim?trico do ?leo de girassol sobre o catalisador mesoporoso citado. Com base nas curvas integrais das an?lises termogravim?tricas e o m?todo cin?tico de Vyazovkin, foram estimados a energia de ativa??o, a convers?o e a degrada??o do ?leo em fun??o da temperatura. O material mesoporoso Al-MCM-41 apresentou forma??o hexagonal unidimensional. O estudo do comportamento cin?tico do ?leo de girassol com o catalisador mostrou uma menor energia de ativa??o frente ? energia de ativa??o do ?leo de girassol puro. Na pir?lise t?rmica e termocatal?tica do ?leo de girassol foram obtidas duas fra??es l?quidas. A primeira fra??o obtida foi denominada de bio?leo e a segunda fra??o obtida foi denominada de fra??o ?cida. A fra??o ?cida coletada tanto na pir?lise t?rmica como na termocatal?tica apresentou ?ndice de acidez muito elevado, raz?o pela qual foi denominada fra??o ?cida. A primeira fra??o coletada foi denominada de bio?leo porque apresentou resultados na faixa semelhante ao diesel de petr?leo
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Complexos N?quel-?-diiminas heterogeneizados em MCM-41 e SBA-15: aplica??o em oligomeriza??o de olefinasRossetto, En?derson 31 July 2015 (has links)
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Previous issue date: 2015-07-31 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Os ligantes ?-diiminas 2-(fenil)amino-4-(fenil)imino-2-penteno e o 2-(2,6-dimetilfenil)amino-4-(2,6-dimetilfenil)imino-2-penteno foram combinados com o grupo alcoxisilano cloropropiltrimetoxisilano (CPTMS) e ancorado covalentemente aos suportes mesoporosos MCM-41 e SBA-15, coordenados pela intera??o com os grupos silan?is da matriz das s?licas e complexados com n?quel. Os complexos Ni-?-diimina/mesoporosos foram sintetizados para aplica??o em rea??es de oligomeriza??o do etileno e do propileno e para compara??o dos resultados entre o sistema homog?neo com o sistema heterog?neo. O suporte foi primeiramente sintetizado e calcinado. Ap?s foi realizado o ancoramento dos ligantes e posterior complexac?o do n?quel. Estes materiais foram caracterizados por v?rias t?cnicas, tais como: RMN de 1H, 13C e 29Si, DRX de baixo ?ngulo, Infra-vermelho (IR), an?lise termogravim?trica, an?lise de isotermas de adsor??o-dessor??o de N2, microscopia eletr?nica de transmiss?o (MET) e de varredura (MEV), an?lise elementar e espectroscopia de absor??o at?mica para confirmar o sucesso das s?nteses dos materiais. Ambos os complexos homog?neos e os heterogeneizados s?o ativos e seletivos para as rea??es de oligomeriza??o do etileno e do propileno. Os materiais heterogeneizados foram menos ativos que os complexos an?logos homog?neos nas rea??es de oligomeriza??o do etileno, por?m, foram mais seletivos tanto para fra??es C4 quanto para ?-C4. Nas rea??es com o propileno os complexos homog?neos promoveram ? rea??o de dimeriza??o e os complexos heterogeneizados ? rea??o de alquila??o do tolueno com o propileno. / The ?-diimine ligands 2-(phenyl)amine-4-(phenyl)imine-2-pentene and 2-(2,6-
dimethylphenyl)amine-4-(2,6-dimethylphenyl)imine-2-pentene were combined with the
alkoxysilane group chloropropyltrimethoxysilane (CPTMS) and covalently anchored to
a mesoporous MCM-41, Al-MCM-41 and SBA-15 support, ordered by interaction with
the silanols of the silica matrix and complexed with nickel. The complexes were
synthesized for application in ethylene and propylene oligomerization and for
comparing results between homogeneous and heterogeneous systems. The support is
first synthesized, calcined, anchored to the ligand, and then subsequent complexation of
nickel is realized. These materials were characterized by several techniques such as 1H,
13C and 29Si NMR, small angle XRD, Infra-red, thermogravimetric analysis, nitrogen
adsorption-desorption isotherms, transmission and scanning electron microscopy,
elemental analysis, and flame atomic absorption spectroscopy, to confirm the success of
the synthesis. Both homogeneous and heterogeneous complexes are active and selective
for the reactions of ethylene and propylene oligomerization. The heterogenized
materials were less active than the homogeneous analogous complexes in the reactions
of oligomerization of ethylene, however, were more selective for both C4 fractions and
for ?-C4. In reactions with propylene, the homogeneous complexes promoted the
dimerization reaction and the heterogenized complexes the alkylation reaction of
toluene with propylene complex.Complexes were tested in recycle reactions proved to
be efficient for use in large scale.
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[en] CATALYSTS SUPPORTED IN MICRO AND MESOPOROUS MOLECULAR SIEVES FOR THE FISCHER- TROPSCH SYNTHESIS / [pt] CATALISADORES SUPORTADOS EM PENEIRAS MOLECULARES MICRO E MESOPOROSAS PARA A SÍNTESE DE FISCHER-TROPSCHJAQUELINE FARIAS DA SILVA 06 April 2005 (has links)
[pt] A síntese de Fischer-Tropsch converte o gás de síntese (H2
+ CO), em uma
variedade complexa de hidrocarbonetos na presença de um
catalisador
(principalmente Co/Al2O3). Neste trabalho foram estudados
catalisadores de Co e
o Fe (1 e 5% em massa), incorporados aos suportes: zeólitas
KL, HL 0,1M e HL
1,0 M, além da peneira molecular mesoporosa MCM- 41, pelo
método de
impregnação úmida incipiente, para a reação de Fischer-
Tropsch.
As amostras preparadas foram analisadas pelas técnicas de:
Espectometria
de Emissão Atômica de Plasma Acoplado Induzido, Adsorção
Física de N2 pelo
método BET, Difração de Raios-X, Redução com Temperatura
Programada,
Microscopia Eletrônica de Transmissão (MET), Quimissorção
de Hidrogênio e
Espectroscopia no Infravermelho de piridina adsorvida. Além
disso, as amostras
foram avaliadas em um reator de leito fixo na reação de
Fischer-Tropsch.
Para as amostras de ferro, com mesmo teor e suportes
diferentes, pode-se
observar que a amostra suportada na MCM-41 apresentou um
grau de redução
menor. Entre as amostras de ferro suportadas na KL, a 5%
Fe/KL apresentou
maior grau de redução e foi observado por microscopia
eletrônica de transmissão
(MET) que as partículas de ferro apresentaram diâmetro em
torno de 6 nm.
Para as amostras de cobalto foi observado que a temperatura
de redução da
amostra suportada na MCM-41 foi mais alta. A amostra 5%
Co/KL apresentou
um maior grau de redução. Foi possível observar por MET que
as partículas de
cobalto apresentaram diâmetro variando entre 8 e 20 nm.
Verificou-se que o catalisador com maior teor de ferro
proporcionou uma maior
conversão de CO, tendo sido a distribuição de produtos
deslocada para as frações
mais leves. Comparando os catalisadores de ferro suportados
na zeólita KL e na
MCM-41 pode-se concluir que as conversões são da mesma
ordem de grandeza.
Foi observado que o ferro foi mais ativo que o cobalto em
termos de conversão do CO, sendo que o cobalto promoveu a
formação de uma maior quantidade de
produtos na faixa de diesel, assim como uma menor
quantidade de leves. / [en] The Fischer- Tropsch synthesis converts the synthesis gas
(H2 + CO), in a
complex variety of hydrocarbons, using a catalyst (Co/Al2O3
normally) were
introduced to the used supports by the wetness incipient
impregnation.
The samples were analyzed by several techniques such as:
plasma- emission
spectrometry (ICP- EAS), N2 physical adsorption by BET
method, X-ray
diffraction (XRD), temperature programmed reduction (TPR),
transmission
electronic microscopy (TEM), hydrogen chemisorption and
Infrared Spectroscopy
of adsorbed pyridine. The catalysts were evaluated using a
fixed bed reactor in the
Fischer-Tropsch synthesis. For the iron samples, with the
same metal content and
different supports, it was observed that the MCM-41 sample
presented the lowest
reduction level. Among the iron samples supported in KL
zeolite, the 5% Fe/KL
sample presented the largest reduction level. It was
observed by transmission
electronic microscopy that the iron particles diameter
measured around 6 nm.
For the cobalt samples, it was observed that the reduction
temperature of the
MCM-41 supported was the highest one. The 5% Co/KL sample
presented the
largest reduction level. It was observed by TEM that the
cobalt particles presented
diameters in the range from 8 to 20 nm. It was verified
that the catalyst with the
largest iron percentage promoved the highest CO conversion.
The products
distribuition was shifted to light fractions. It was
observed similar conversions to
iron catalysts supported in the KL zeolite and in the MCM-
41 mesoporous
molecular sieve. The iron catalysts were more active than
the cobalt ones in the
CO conversion, but tha cobalt catalysts promoted a higher
content of diesel
fraction and lesser light fractions.
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S?ntese e caracteriza??o da peneira molecular MCM-41 contendo terras raras na dessulfuriza??o, utilizando tiofeno como mol?cula sondaAlves, Jos? Ant?nio Barros Leal Reis 27 May 2010 (has links)
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Previous issue date: 2010-05-27 / Mesoporous molecular sieves of MCM-41 type are considered as
promising support for metal in the refining processes of petroleum-based
materials as catalysts and adsorbents for environmental protection. In this work,
mesoporous molecular sieves MCM-41 were modified with different rare earth
ions (La, Eu e Yb) for the obtaining nanostrutured materials with catalytic
properties. The catalysts were synthesized by the hydrothermal method at
100oC for 120 h, presenting, all the samples, in the gel of synthesis molar ratio
Si/Ln = 50. The obtained materials after calcination at 500oC for 2 h were
characterized by XRD, surface area BET, TG/DTG, FTIR, and hydrothermal
stability at 700?C. The XRD analysis of the catalysts indicated that the materials
containing rare earth presented characteristic hexagonal structure of the
mesoporous materials of the type MCM-41. The TG curves showed that the
decomposition of the structural template occurs in the materials at temperatures
lower than 500oC. The samples presented variations as the specific superficial
area, average diameter of pores and thickness of the silica wall, as a function of
the nature of the rare earth impregnated in the mesoporous material.
Hydrotermal stability was evaluated through the exposition of the materials to
water vapour at 700?C. The thiophene adsorptions reach a maximum at 80% of
conversion and incorporation of the rare earths showed influence in the
process. Adsorption capacity followed the sequence: Yb-MCM-41 < La-MCM-41
< Eu-MCM-41 < MCM-41 / As peneiras moleculares mesoporosas do tipo MCM-41 s?o
consideradas promissoras como suporte para metais em processos de refino
de materiais a base de petr?leo, como catalisadores e como adsorventes para
prote??o ambiental. Neste trabalho a peneira molecular mesoporosa tipo
MCM-41 foi modificada com diferentes terras raras (La, Eu e Yb) para a
obten??o de materiais nanoestruturados com propriedades catal?ticas. Os
catalisadores foram sintetizados pelo m?todo hidrot?rmico a 100 oC por 120
horas, apresentando, todas as amostras, no gel de s?ntese raz?o molar Si/Ln =
50. Os materiais resultantes, ap?s calcina??o a 500 oC por 2 horas, foram
caracterizados por: DRX, ?rea superficial pelo m?todo de BET, TG/DTG, FTIR
e testes hidrot?rmicos a 700oC. As an?lises de DRX dos catalisadores
indicaram que os materiais contendo as terras raras apresentaram estrutura
hexagonal caracter?stica do material mesoporoso tipo MCM-41. As curvas TG
mostraram que a decomposi??o do direcionador estrutural ocorre nos materiais
em temperaturas inferiores a 500oC. As amostras apresentaram varia??es
quanto ? ?rea superficial espec?fica, di?metro m?dio de poros e espessura da
parede de s?lica, em fun??o da natureza da terra rara impregnada no material
mesoporoso. A estabilidade hidrot?rmica foi avaliada atrav?s da exposi??o dos
materiais a vapor d ?gua a 700oC. A adsor??o de tiofeno atingiu valores
m?ximos de 80% e a incorpora??o das terras raras influenciaram no processo.
A ordem crescente de capacidade de adsor??o seguiu a seguinte seq??ncia:
Yb-MCM-41 < La-MCM-41 < Eu-MCM-41 < MCM-41
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Craqueamento t?rmico e termocatal?tico do ?leo de girassol (Hellianthus annus L.) sobre materiais micro e mesoporosos / Craqueamento t?rmico e termocatal?tico do ?leo de girassol (Hellianthus annus L.) sobre materiais micro e mesoporososMelo, Ana Cl?udia Rodrigues de 06 December 2010 (has links)
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Previous issue date: 2010-12-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Microporous materials zeolite type Beta and mesoporous type MCM-41 and
AlMCM-41 were synthesized hydrothermally and characterized by methods of X-ray
diffraction, Fourier transform infrared, scanning electron microscopy, surface acidity,
nitrogen adsorption, thermal analysis TG / DTG. Also we performed a kinetic study of
sunflower oil on micro and mesoporous catalysts. The microporous material zeolite beta
showed a lower crystallinity due to the existence of smaller crystals and a larger number
of structural defects. As for the mesoporous materials MCM-41 and AlMCM-41
samples showed formation of hexagonal one-dimensional structure. The study of
kinetic behavior of sunflower oil with zeolite beta catalysts, AlMCM-41 and MCM-41
showed a lower activation energy in front of the energy of pure sunflower oil, mainly
zeolite beta. In the thermal cracking and thermocatalytic of sunflower oil were obtained
two liquid fractions containing an aqueous phase and another organic - organic liquid
fraction (FLO). The FLO first collected in both the thermal cracking as the
thermocatalytic, showed very high level of acidity, performed characterizations of
physicochemical properties of the second fraction in accordance with the specifications
of the ANP. The second FLO thermocatalytic collected in cracking of sunflower oil
presented results in the range of diesel oil, introducing himself as a promising
alternative for use as biofuel liquid similar to diesel, either instead or mixed with it / Os materiais microporosos tipo ze?lita beta e mesoporosos tipo MCM-41 e
AlMCM-41 foram sintetizados hidrotermicamente e caracterizados pelos m?todos de
difra??o de raios X, infravermelho por transformada de Fourier, microscopia eletr?nica
de varredura, acidez superficial, adsor??o de nitrog?nio, an?lise t?rmica via TG/DTG.
Ainda foi realizado um estudo do comportamento cin?tico termogravim?trico do ?leo de
girassol sobre os catalisadores micro e mesoporosos citados. Usando curvas integrais da
TG e o m?todo cin?tico de Vyazovkin, foram estimados a energia de ativa??o, as taxas
de convers?o e o tempo degrada??o do ?leo em fun??o da temperatura. O material
microporoso ze?lita beta apresentou menor cristalinidade, devido ? exist?ncia de cristais
menores e um maior n?mero de defeitos estruturais. Quanto aos materiais mesoporosos
MCM-41 e AlMCM-41 apresentaram amostras com forma??o da estrutura hexagonal
unidimensional. O estudo do comportamento cin?tico do ?leo de girassol com os
catalisadores ze?lita beta, AlMCM-41 e MCM-41, mostrou uma menor energia de
ativa??o frente a energia do ?leo de girassol puro, principalmente a ze?lita beta. No
craqueamento t?rmico e termocatal?tico do ?leo de girassol foram obtidas duas fra??es
l?quidas contendo uma fase aquosa e outra org?nica fra??o l?quida org?nica (FLO). A
primeira FLO coletada, tanto no craqueamento t?rmico quanto no termocatal?tico,
apresentou ?ndice de acidez muito elevado, sendo assim foi realizada as caracteriza??es
das propriedades f?sico-qu?micas da segunda fra??o de acordo com as especifica??es da
ANP. As segundas FLOs coletadas no craqueamento termocatal?tico do ?leo de girassol
apresentaram resultados na faixa adequada ao diesel de petr?leo, apresentando-se como
uma alternativa promissora para utiliza??o como biocombust?vel l?quido similar ao
diesel, seja em substitui??o, ou misturado a este
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Estudo cin?tico da degrada??o t?rmica e catal?tica de petr?leo pesado usando Al-MCM-41Oliveira, Aline Ara?jo Alves de 09 August 2013 (has links)
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Previous issue date: 2013-08-09 / The mesoporous nanostructured materials have been studied for application in
the oil industry, in particular Al-MCM-41, due to the surface area around 800 to 1.000
m2 g-1 and, pore diameters ranging from 2 to 10 nm, suitable for catalysis to large
molecules such as heavy oil. The MCM-41 has been synthesized by hydrothermal
method, on which aluminum was added, in the ratio Si/Al equal to 50, to increase the
generation of active acid sites in the nanotubes. The catalyst was characterized by X-ray
diffraction (XRD), surface area by the BET method and, the average pore volume BJH
method using the N2 adsorption, absorption spectroscopy in the infrared Fourier
Transform (FT-IR) and determination of surface acidity with application of a probe
molecule - n-butylamine. The catalyst showed well-defined structural properties and
consistent with the literature. The overall objective was to test the Al-MCM-41 as
catalyst and thermogravimetric perform tests, using two samples of heavy oil with API ?
equal to 14.0 and 18.5. Assays were performed using a temperature range of 30-900 ? C
and heating ratios (β) ranging from 5, 10 and 20 ?C min-1.The aim was to verify the
thermogravimetric profiles of these oils when subjected to the action of the catalyst Al-
MCM-41. Therefore, the percentage ranged catalyst applied 1, 3, 5, 10 and 20 wt%, and
from the TG data were applied two different kinetic models: Ozawa-Flynn-Wall (OFW)
and Kissinger-Akahrira-Sunose (KAS).The apparent activation energies found for both
models had similar values and were lower for the second event of mass loss known as
cracking zone, indicating a more effective performance of Al-MCM-41 in that area.
Furthermore, there was a more pronounced reduction in the value of activation energy
for between 10 and 20% by weight of the oil-catalyst mixture. It was concluded that the
Al-MCM-41 catalyst has applicability in heavy oils to reduce the apparent activation
energy of a catalyst-oil system, and the best result with 20% by weight of Al-MCM-41 / Os materiais mesoporosos nanoestruturados vem sendo estudados para aplica??o
na ind?stria do petr?leo, em especial o Al-MCM-41, devido ? ?rea superficial em torno
de 800-1000 m2g-1 e di?metro de poros variando de 2 a 10 nm, adequado para cat?lise
de mol?culas grandes como petr?leos pesados. O MCM-41 foi sintetizado pelo m?todo
hidrot?rmico, o qual foi adicionado Alum?nio numa propor??o Si/Al igual ? 50, a fim de
aumentar a gera??o de s?tios ?cidos ativos nos nanotubos. O catalisador foi
caracterizado por difra??o de Raios-X (DRX), ?rea superficial pelo m?todo BET e
volume m?dio de poros pelo m?todo BJH atrav?s da adsor??o de N2, espectroscopia de
absor??o na regi?o do infravermelho por Transformada de Fourier (FT-IR) e
determina??o da acidez superficial com aplica??o de uma mol?cula sonda nbutilamina.
O catalisador apresentou propriedades estruturais bem definidas e coerentes
com a literatura. O objetivo geral foi testar o Al-MCM-41 como catalisador e realizar
ensaios termogravim?tricos, utilizando duas amostras de petr?leo pesado com ?API
iguais ? 14,0 e 18,5. Os ensaios foram realizados usando uma faixa de temperatura de
30 900?C, e raz?es de aquecimento (β) variando de 5, 10 e 20 ?Cmin-1. O intuito era
verificar os perfis termogravim?tricos destes petr?leos quando submetidos ? a??o do
catalisador Al-MCM-41. Para tanto, variou-se o percentual de catalisador aplicado in
situ: 1, 3, 5, 10 e 20% em massa e, a partir dos dados termogravim?tricos foram
aplicados dois modelos cin?ticos diferentes: Ozawa-Flynn-Wall (OFW) e Kissinger-
Akahrira-Sunose (KAS). As energias de ativa??o aparente encontradas para ambos os
modelos tinham valores semelhantes e eram menores para o segundo evento de perda de
massa conhecido como zona de craqueamento, indicando uma atua??o mais efetiva do
Al-MCM-41 nessa zona. Al?m disso, constatou-se uma diminui??o mais acentuada no
valor das energias de ativa??o para valores entre 10 e 20% em massa da mistura
catalisador-?leo. Concluiu-se que o Al-MCM-41 possui aplicabilidade catal?tica em
petr?leos pesados diminuindo a energia de ativa??o aparente de um sistema catalisador?leo,
sendo o melhor resultado com 20% em massa de Al-MCM-41
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Novel Bimetallic Mesoporous Catalysts For Hydrogen Production Through Steam Reforming Of EthanolSener, Canan 01 September 2012 (has links) (PDF)
Hydrogen is considered as an alternative clean energy source due to the depletion of fossil fuels and related environmental problems. Steam reforming of bio-ethanol, has excellent potential for hydrogen production, with CO2 neutrality. Ni, Pd and Pt are the most active metals for steam reforming of ethanol. Improving catalytic activity of supported Ni catalyst by incorporating small amount of Pd or Pt is a successful method for increasing activity and stability of the catalyst. Development of active and stable catalysts with low coke formation and high hydrogen yield attracted major attention of researchers in recent decades.
MCM-41 supported bimetallic mesoporous catalytic materials containing well dispersed Ni and Pd nanoballs were synthesized following an impregnation procedure. TEM images and XRD analysis of these materials indicated the formation of nickel and palladium nanoballs of 15-25 nm and 5-8 nm respectively, within the synthesized materials. These materials have quite narrow pore-size distributions in the range of 1-5 nm. In the calcined materials, nickel was in Ni+3 and Ni+2 states, however in the reduced sample most of the nickel was in Nio state, together with some NiO. Formation of NiOx crystals takes place after the calcination step. Impregnation of palladium into Ni/MCM-41 caused a decrease in the reduction temperature of NiO for about 50oC. Activity of the catalytic materials were tested in the reaction of steam reforming of ethanol.all the catalysts showed high conversion and quite high hydrogen yield over 400 oC. PdNi impregnated MCM-41 supported catalysts showed higher conversion of ethanol but lower hydrogen yield than Ni impregnated catalysts due to methane formation in the case of Pd incorporation.
However, MCM-41 does not show enough hydrothermal stability for steam reforming of ethanol reaction. SBA-15 has very similar physical properties of MCM-41 with larger pores and high hydrothermal stability. Ceria also has widespread applications in catalysis area with its excellent oxygen buffering capacity. It can be used as catalyst support and also an improving agent for silica supports.
Mesoporous silica SBA-15 with ordered pore structure was synthesized following a hydrothermal procedure and then bimetallic Ni-Ce and Pd-Ni-Ce incorporated mesoporous silica catalysts were prepared and tested in steam reforming of ethanol. On the other hand, ceria enriched silica structures i.e cerium/silicate composites were also synthesized. However the syntheses were unsuccessful due to the thermal sintering of ceria.
Addition of ceria to the support structure decreased coke formation significantly.. According to the thermal gravimetric analysis studies conducted after ethanol steam reformin reaction at 600 oC, coke formation with Ni-SBA-15 (Ni/Si=0.10) catalyst was 40% and it was 10% with NiCe-SBA-15 (Ni/Si=0.10, Ce/Si=0.50) Activity test results obtained with Ni incorporated silica catalysts in steam reforming of ethanol gave high hydrogen yield over 4 (max. 6) and complete conversion of ethanol at 600 oC. SBA-15 found to be more stable catalyst than MCM-41 in the steam reforming of ethanol reaction.
The highest hydrogen yield values were achieved by AlMCM-41 supported Ni-Ce impregnated catalysts. Aluminum in the slica matrix (3% wt.) increased the catalytic activity significantly, by giving acidic properties to the catalyst. Simultaneous and consecutive Ni and Ce impregnation were also examined. AlMCM-41 supported, consecutively Ce and Ni impregnated catalysts with Ce/Si and Ni.Si molar ratio sof 0.10, showed very high catalytic activity (5.8 at the beginning). AlMCM-41 supported catalyst were less stable because of high activity and consequently coke formation.
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Desenvolvimento de Peneiras Moleculares MCM-41 E Al-MCM-41, via processo hidrotermal assistido por micro-ondas. / Development of Molecular Sieves MCM-41 and Al-MCM-41, via microwave assisted hydrothermal process.MEDEIROS, Cláudia Dourado. 30 April 2018 (has links)
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Previous issue date: 2014-04-02 / Capes / As peneiras moleculares mesoporosas possuem um arranjo hexagonal de
mesoporos com diâmetros de poros que variam de 2 a 10 nm, possuindo assim uma
área superficial elevada. A adição de um metal a sua estrutura tem como função
gerar a acidez ao material o tornando mais reativo, aumentado assim a possibilidade
do seu uso como catalisador na indústria do petróleo. Atualmente, um dos
problemas encontrados pelos pesquisadores para obtenção desse tipo de peneira, é
o longo tempo de formação das estruturas. No presente trabalho as peneiras
moleculares mesoporosas MCM-41 e Al-MCM-41 foram sintetizadas utilizando dois
processos hidrotermais, a tradicional e por micro-ondas, com o objetivo principal de
reduzir o tempo de síntese do material. A peneira molecular MCM-41 foi sintetizada
utilizando o processo hidrotermal tradicional, 100 oC por 48 horas , como também
utilizando o processo hidrotermal de micro-ondas através de três metodologias,
adotando diferentes tempos e temperaturas. Tomando como base os resultados
obtidos com as sínteses da peneira molecular MCM-41 por meio do método
hidrotermal de micro-ondas, os mesmos métodos foram aplicados para a peneira
molecular Al-MCM-41 nas mesmas condições de tempo e temperatura. Através dos
difratogramas foi possível perceber que a estrutura hexagonal foi formada. Verificouse
que o melhor tempo de síntese da Al-MCM-41 se deu com 60 minutos a 130 oC.
A partir destes dados, foram realizadas novas sínteses, reduzindo o tempo
gradativamente. Os resultados das análises de DRX, MEV e FTIR comprovam que
as peneiras moleculares mesoporosas foram formadas, sendo possível identificar
sua estrutura e morfologia. Os melhores resultados de síntese para as peneiras
moleculares mesoporosas MCM-41 e Al-MCM-41, foram nos tempos 60 e 40
minutos e temperatura de 130 oC, respectivamente. / The mesoporous molecular sieves have a hexagonal arrangement of
mesopores with pore diameters ranging from 2 to 10 nm, which implies in a high
surface area. The addition of a metal into these structures has the function of
generating acidity in the material making it more reactive, increasing the possibility of
using it as a catalyst into the oil industry. Nowadays, one of the problems found by
researches to obtain these type of molecular sieves is the long time of structure
formation taken by these materials. In this study, the mesoporous molecular sieves
MCM - 41 and Al -MCM -41 were synthesized using two traditional microwave, with
the primary goal of reducing the time of synthesis of the material hydrothermal
processes. The molecular sieve MCM -41 was synthesized using the traditional
hydrothermal process 100 °C for 48 hours , as well as hydrothermal process using
microwave by three methods , adopting different times and temperatures . Based on
the results obtained with the synthesis of molecular sieve MCM -41 by hydrothermal
microwave method, the same methods were applied to the molecular sieve Al -MCM
-41 under the same conditions of time and temperature. Through the DRX patterns
was observed that the hexagonal structure was formed. It was found that the best
time of synthesis of Al- MCM-41 was given 60 minutes at 130 oC. From these data,
new syntheses were carried out by reducing the time gradually. The results of DRX,
MEV and FTIR show that the mesoporous molecular sieves were formed, it is
possible to identify their structure and morphology. The best results for the synthesis
of mesoporous molecular sieves MCM - 41 and Al -MCM -41, were at times 60 and
40 minutes and temperatures of 130 °C, respectively.
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