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S?ntese e Caracteriza??o de Titanatos de Cobalto e N?quel, dopados com Praseod?mio, obtidos a partir da decomposi??o de NitrilotriacetatosFonseca, Saulo Gregory Carneiro 28 February 2013 (has links)
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Previous issue date: 2013-02-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In recent years, studies about the physicochemical properties of mixed oxides, call
attention of the scientific community, properties like as piezoelectricity, photoluminescence,
or applications as catalysts, arise in these compounds, when their chemical compositions are
modified, in this context some routes are employed in the synthesis of these materials, among
which can be cited these methods: ceramic, combustion, co-precipitation, Pechini or
polymeric precursor method, hydrothermal, sol-gel; these routes are divided into traditional
routes or chemical routes. In this work were synthesized oxides with variable composition,
from the thermal decomposition of titanium, cobalt, nickel and praseodymium
nitrilotriacetates. The nitrilotriacetates were characterized by IR Spectroscopy (FTIR),
Thermogravimetric (TG/ DTG) and Differential Scanning Calorimetry (DSC), while oxides
have been characterized by X-ray diffraction (XRD), Spectrofluorimetry and IR Spectroscopy
(FTIR). From FTIR data, it was demonstrated that the displacement of the band
corresponding to the carboxylate group (νCOOH) at 1712 cm-1, present in nitrilotriacetic acid
(H3NTA), for 1680-1545 cm-1, these stretches are characteristics of coordinated
nitrilotriacetates, By thermal analysis (TG/DTG /DSC), it was suggested, that in an oxidizing
atmosphere (air) oxides are obtained at lower temperatures than in an inert atmosphere N2(g).
By results from X-ray Diffraction (XRD), it was determinated that the oxides are crystalline
and the predominant phases obtained are summarized titanate phases rutile and ilmenite. By
fluorimetry was observed that the intensity of emission bands are directly proportional to the
concentration of ions Ni2+, Co2+ and Pr3+, and IR spectroscopy (FTIR) from oxides,
demonstrated the disappearance of characteristic bands by nitrilotriacetates, determining the
complete decomposition of the nitrilotriacetates in oxides / Nos ?ltimos anos, os estudos das propriedades f?sico-qu?micas de ?xidos mistos, tem
despertado o interesse da comunidade cient?fica, propriedades como: piezoeletricidade,
fotoluminesc?ncia, ou aplica??es em cat?lise, surgem destes compostos quando se modifica as
composi??es qu?micas destes materiais, neste contexto algumas rotas s?o empregadas na
s?ntese destes materiais, dentre elas pode-se citar os m?todos: cer?mico, combust?o coprecipita??o,
Pechini ou dos precursores polim?ricos, hidrot?rmico, sol-gel; tais rotas
dividem-se em rotas tradicionais ou em rotas qu?micas. No presente trabalho foram
sintetizados ?xidos com composi??o vari?vel, a partir das decomposi??es t?rmicas dos
nitrilotriacetatos de tit?nio, cobalto, n?quel e praseod?mio. Os nitrilotriacetatos obtidos foram
caracterizados por Espectroscopia de Absor??o na Regi?o do Infravermelho (FTIR),
Termogravimetria (TG/DTG) e Calorimetria Explorat?ria Diferencial (DSC), enquanto que os
?xidos sintetizados foram caracterizados por Difra??o de Raios-X (DRX),
Espectrofluorimetria e Espectroscopia de Absor??o na Regi?o do Infravermelho (FTIR). A
partir dos dados de Espectroscopia de Absor??o na Regi?o de Infravermelho (FTIR),
determinou-se o deslocamento da banda correspondente ao grupo carboxilato (νCOOH) de 1712
cm-1, presente no ?cido nitrilotriac?tico (H3NTA), para a faixa de 1680-1545cm-1, em que
ocorre nos nitrilotriacetatos coordenados. Pelos dados de an?lise t?rmica (TG/DTG/DSC)
indicou-se que em atmosfera oxidante (ar) os ?xidos s?o obtidos a menores temperaturas do
que em atmosfera inerte N2(g). Por Difra??o de Raios-X (DRX), determinou-se que os ?xidos
obtidos s?o cristalinos, e que as fases predominantes obtidas nos titanatos sintetizados, s?o as
fases rutilo e ilmenita. Por Espectrofluorimetria observou-se que a intensidade das bandas de
emiss?o s?o diretamente proporcionais ? concentra??o dos ?ons Ni2+, Co2+ e Pr3+. A partir dos
dados fornecidos pela Espectroscopia de Absor??o na Regi?o do Infravermelho (FTIR) dos
?xidos, demonstrou-se a remo??o das bandas caracter?sticas dos estiramentos dos
nitrilotriacetatos, ap?s tratamento t?rmico, indicando a completa decomposi??o dos
nitrilotriacetatos em ?xidos
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Degrada??o do PMMA atrav?s da rea??o despolimeriza??o uitlizando catalisadores de ?xidos mistosClericuzi, Genaro Zenaide 29 May 2009 (has links)
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Previous issue date: 2009-05-29 / In this work, mixed oxides were synthesized by two methods: polymeric precursor and gel-combustion. The oxides, Niquelate of Lanthanum, Cobaltate of Lanthanum and Cuprate of Lanthanum were synthesized by the polymeric precursor
method, and treated at 300 ? C for 2 hours, calcined at 800 ? C for 6h in air atmosphere. In gel-combustion method were produced and oxides using urea and citric acid as fuel, forming for each fuel the following oxides Ferrate of Lanthanum,
Cobaltato of Lanthanum and Ferrato of Cobalt and Lanthanum, which were submitted to the combustion process assisted by microwave power maximum of 10min.
The samples were characterized by: thermogravimetric analysis, X-ray diffraction; fisisor??o of N2 (BET method) and scanning electron microscopy. The reactions catalytic of depolymerization of poly (methyl methacrylate), were performed in a reactor of silica, with catalytic and heating system equipped with a data acquisition system and the gas chromatograph. For the catalysts synthesized using the polymeric precursor method, the cuprate of lanthanum was best for the depolymerization of the recycled polymer,
obtaining 100% conversion in less time 554 (min), and the pure polymer, was the Niquelate of Lanthanum, with 100% conversion in less time 314 (min). By gel-combustion method using urea as fuel which was the best result obtained Ferrate of Lanthanum for the pure polymer with 100% conversion in less time 657 (min), and the recycled polymer was Cobaltate of Lanthanum with 100 % conversion in less time 779 (min). And using citric acid to obtain the best result for the pure polymer, was Ferrate of Lanthanum with 100% conversion in less time 821 (min and) for the recycled polymer, was Ferrate of Lanthanum with 98.28% conversion in less time 635 (min) / Neste trabalho, foram sintetizados ?xidos mistos por dois m?todos: precursores polim?ricos e gel-combust?o. Os ?xidos, Niquelato de Lant?nio, Cobaltato de Lant?nio e Cuprato de Lant?nio, foram sintetizados pelo m?todo dos precursores
polim?ricos, sendo tratados termicamente a 300 ?C por 2h, calcinados a 800 ?C por 6h, em atmosfera de ar. No m?todo gel-combust?o foram produzidos os ?xidos utilizando como combust?vel Ur?ia e ?cido C?trico, formando para cada combust?vel os seguintes ?xidos Ferrato de Lant?nio, Cobaltato de Lant?nio e Ferrato de Cobalto e Lant?nio, que foram submetidos ao processo de combust?o assistida por
microondas ? pot?ncia m?xima por 10min. As amostras foram caracterizadas por: an?lise termogravim?trica; difra??o de raio-X; fisisor??o de N2 (m?todo de B.E.T.) e microscopia eletr?nica de varredura. As rea??es catal?ticas de despolimeriza??o do Poli (metacrilato de metila), foram
realizadas em um reator de s?lica, com sistema catal?tico e aquecimento munido de um sistema de aquisi??o de dados e o cromat?grafo a g?s. Para os catalisadores sintetizados utilizando o m?todo dos precursores polim?ricos, o Cuprato de Lant?nio, foi melhor para a despolimeriza??o do pol?mero reciclado, obtendo 100 % de convers?o em menor tempo 554 (min), e para o pol?mero puro, foi o Niquelato de Lant?nio, com 100 % de convers?o em menor tempo 314 (min).
Pelo m?todo de gel-combust?o utilizando Ur?ia como combust?vel o que obteve melhor resultado foi o Ferrato de Lant?nio, para o pol?mero puro com 100 % de convers?o em menor tempo 657 (min), e para o pol?mero reciclado foi o Cobaltato de Lant?nio com 100 % de convers?o em menor tempo 779 (min). E utilizando ?cido C?trico o que obteve melhor resultado para o pol?mero puro, foi o Ferrato de Lant?nio com 100 % de convers?o em menor tempo 821 (min) e para o pol?mero reciclado, foi o Ferrato de Lant?nio com 98,28 % de convers?o em menor tempo 635 (min)
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Prepara??o de ?xidos mistos de n?quel e zinco nanoparticulados a partir de combust?veis alternativosSilva, Rayssa Rafaelli Nunes Melo da 31 August 2012 (has links)
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Previous issue date: 2012-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The field of "Materials Chemistry" has been developing in recent years and there has
been a great increase of interest in the synthesis and chemical and physical properties of
new inorganic solids. New routes of synthesis and synthesis modified has been
developed with the aim not only to optimize the processes in laboratory scale, but also
on an industrial scale, and make them acceptable by current environmental legislation.
The phenomenology of current solid state chemistry properties coupled with the high
temperature superconductivity, ferromagnetism, porosity molecular and colors are
evidence affected by the synthesis method, which in turn can influence the
technological application of these materials. From this understanding, mixed oxides of
nickel and zinc nanoparticulate were synthesized by microwave-assisted combustion
route using three specific types of organic fuels employing the weight ratios 1:1/2 and
1:1 of cation metallic/fuel, in order to investigate the influence of such proportions to
obtain the solids. The new fuels were chosen to replace, for example, urea or glycine
that are the fuels most commonly preferred in this kind of synthesis. The powders
without heat treatment were studied by Thermogravimetric analysis (TGA), X-Ray
Diffraction (XRD) and then calcined at 900?C. After heat treatment, the samples were
characterized by analysis of X Ray Diffraction (XRD) and Scanning Electron
Microscopy (SEM). The modified synthesis route porposed was effective for obtaining
powders. Both the alternative fuels chosen as the different weight ratios employed,
influenced in the morphology and obtaining oxides / O campo da Qu?mica de Materiais vem se desenvolvendo nos ?ltimos anos, tendo
havido um grande aumento do interesse na s?ntese e nas propriedades qu?micas e f?sicas
de novos s?lidos inorg?nicos. Novas rotas de s?nteses e s?nteses modificadas tem sido
desenvolvidas com o intuito n?o apenas de otimizar os processos em escala
laboratorial, como tamb?m em escala industrial, al?m de torn?-los aceit?veis pela
legisla??o ambiental vigente. A atual fenomelogia da qu?mica do estado s?lido aliada ?s
propriedades de supercondutividade ? alta temperatura, ferromagnetismo, porosidade
molecular e cores s?o evid?ncias afetadas pelo m?todo de s?ntese, que por sua vez,
podem influenciar na aplica??o tecnol?gica desses materiais. Foi a partir desta
compreens?o, que ?xidos mistos de n?quel e zinco nanoparticulados foram sintetizados
atrav?s da rota combust?o por microondas utilizando tr?s tipos espec?ficos de
combust?veis e empregando as raz?es m?ssicas 1:1 e 1:1/2 de c?tions
met?licos/combust?vel, com o intuito de averiguar a influ?ncia de tais propor??es na
obten??o dos s?lidos. Os novos combust?veis foram escolhidos em substitui??o a ur?ia
ou glicina que s?o mais comumente preferidos nesse tipo de s?ntese. Os p?s sem
tratamento t?rmico foram estudados atrav?s da An?lise Termogravim?trica (ATG) e da
Difra??o de Raios-X (DRX), sendo, em seguida, submetidos ao tratamento t?rmico ?
900?C. Ap?s as calcina??es, foram caracterizados atrav?s das an?lises Difra??o de raiosx
(DRX) e Microscopia Eletr?nica de Varredura (MEV). A rota de s?ntese modificada
foi eficaz para obten??o dos p?s. Tanto os combust?veis alternativos escolhidos quanto
as diferentes raz?es m?ssicas empregadas, influenciaram na morfologia e na obten??o
dos ?xidos
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