Estudo da oxidação preferencial do CO por catalisadores a base de irídio

Detalhes bibliográficos
Autor(a) principal: Silva Júnior, Waldir da
Data de Publicação: 2014
Tipo de documento: Dissertação
Idioma: por
Título da fonte: Repositório Institucional da UFSCAR
Texto Completo: https://repositorio.ufscar.br/handle/ufscar/4152
Resumo: Ir/Al2O3 samples were prepared to evaluate the influence of the particle size of the metal in the preferential oxidation of CO reaction. Initially, samples with different amounts of iridium were prepared in an attempt to get different particle sizes. Samples containing 1, 2, 6 and 10 % Ir/Al2O3 were prepared. The samples were prepared via dry impregnation, from alcoholic solutions of the salt precursor and calcined at a temperature of 400 °C. The -Al2O3 support was calcined at 550 °C. The catalytic tests were carried out using a flow rate of 100 ml/min of a mixture containing 1% O2, 1% CO, 45% H2 and balance in He. The results of XRD of these samples showed no characteristic peaks of iridium and the metal dispersions were very similar, raising the possibility that even with the increased loading of iridium samples showed no significant differences in their structure. After realize catalytic tests using the same density of active sites, it was found that the structure of the samples was very similar and the different results of activity and selectivity were due to the different densities of active sites. In order to obtain samples with different structural properties, was fixed in 4% the iridium concentration on the catalysts and was varied the calcination temperature of the catalysts (400, 550 and 750 °C) and the support (550 and 750 °C) and was studied the influence of calcination temperature of the catalyst as well the support. Results of XRD and hydrogen chemisorption showed large differences in particle size and metal dispersion. The total flow of the catalytic tests was reduced to 50 mL/min, maintaining the concentrations of the gases. DRIFTS spectra confirmed the structural differences due to the increase of calcination temperature of catalysts, showing a large decrease in the interaction between CO/metal. The results of the catalytic tests showed that by increasing the calcination temperature of the catalysts there is a loss of activity but these catalysts were more selective. A strong influence of the calcination temperature of the supports in the activity and selectivity of the catalysts was also observed. The results show that the PROX reaction is very sensitive to catalyst structure.
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spelling Silva Júnior, Waldir daBueno, José Maria Corrêahttp://lattes.cnpq.br/0157452280626031http://lattes.cnpq.br/0950063786043919044d7216-4afb-4b52-bfcb-eb77a80495002016-06-02T19:56:56Z2014-11-112016-06-02T19:56:56Z2014-03-31SILVA JÚNIOR, Waldir da. Estudo da oxidação preferencial do CO por catalisadores a base de irídio. 2014. 70 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014.https://repositorio.ufscar.br/handle/ufscar/4152Ir/Al2O3 samples were prepared to evaluate the influence of the particle size of the metal in the preferential oxidation of CO reaction. Initially, samples with different amounts of iridium were prepared in an attempt to get different particle sizes. Samples containing 1, 2, 6 and 10 % Ir/Al2O3 were prepared. The samples were prepared via dry impregnation, from alcoholic solutions of the salt precursor and calcined at a temperature of 400 °C. The -Al2O3 support was calcined at 550 °C. The catalytic tests were carried out using a flow rate of 100 ml/min of a mixture containing 1% O2, 1% CO, 45% H2 and balance in He. The results of XRD of these samples showed no characteristic peaks of iridium and the metal dispersions were very similar, raising the possibility that even with the increased loading of iridium samples showed no significant differences in their structure. After realize catalytic tests using the same density of active sites, it was found that the structure of the samples was very similar and the different results of activity and selectivity were due to the different densities of active sites. In order to obtain samples with different structural properties, was fixed in 4% the iridium concentration on the catalysts and was varied the calcination temperature of the catalysts (400, 550 and 750 °C) and the support (550 and 750 °C) and was studied the influence of calcination temperature of the catalyst as well the support. Results of XRD and hydrogen chemisorption showed large differences in particle size and metal dispersion. The total flow of the catalytic tests was reduced to 50 mL/min, maintaining the concentrations of the gases. DRIFTS spectra confirmed the structural differences due to the increase of calcination temperature of catalysts, showing a large decrease in the interaction between CO/metal. The results of the catalytic tests showed that by increasing the calcination temperature of the catalysts there is a loss of activity but these catalysts were more selective. A strong influence of the calcination temperature of the supports in the activity and selectivity of the catalysts was also observed. The results show that the PROX reaction is very sensitive to catalyst structure.Foram preparadas amostras de Ir/Al2O3 a fim de avaliar a influência do tamanho de partícula do metal na PROX-CO. Inicialmente foram preparadas amostras com diferentes teores de irídio, na tentativa de se obter diferentes tamanhos de partículas. Foram preparadas amostras com teor de irídio de 1, 2, 6 e 10% Ir/Al2O3. As amostras foram preparadas via impregnação seca, a partir de soluções alcoólicas do sal precursor, e calcinadas em temperatura de 400 °C. O suporte -Al2O3 foi calcinado em 550 °C. Os testes catalíticos foram realizados utilizando um fluxo de 100 mL/min de uma mistura contendo 1% O2, 1% CO, 45% H2 e balanço em He. Os resultados de DRX destas amostras não apresentaram picos característicos de irídio e as dispersões metálicas foram muito semelhantes, levantando a hipótese de que mesmo com o aumento da carga de irídio as amostras não apresentavam diferenças significativas em sua estrutura. Após serem realizados testes catalíticos utilizando a mesma densidade de sítios ativos, foi constatado que a estrutura das amostras era muito semelhante e os diferentes resultados de atividade e seletividade eram devidos as diferentes densidades de sítios ativos. Para que se obtivessem amostras com propriedades estruturais diferentes, foi fixada em 4% a concentração de irídio nos catalisadores e variada a temperatura de calcinação dos catalisadores (400, 550 e 750 °C) e do suporte (550 e 750 °C) e foi estudada a influência da temperatura de calcinação tanto do catalisador quanto do suporte. Resultados de DRX e quimissorção de hidrogênio mostraram grandes diferenças de tamanho de partícula e dispersão metálica. O fluxo total dos testes catalíticos foi reduzido para 50 mL/min, mantendo as concentrações dos gases. Os espectros de DRIFTS comprovaram as diferenças estruturais devidas ao aumento de temperatura de calcinação dos catalisadores, mostrando uma grande queda na interação entre CO/metal. O resultado dos testes catalíticos mostrou que com o aumento da temperatura de calcinação dos catalisadores há uma perda de atividade, porém estes catalisadores se mostraram mais seletivos. Também foi observada uma forte influência da temperatura de calcinação dos suportes na atividade e seletividade dos catalisadores. Os resultados mostram que a reação PROX é muito sensível a estrutura dos catalisadores.Universidade Federal de Sao Carlosapplication/pdfporUniversidade Federal de São CarlosPrograma de Pós-Graduação em Engenharia Química - PPGEQUFSCarBRCatáliseOxidação preferencialIrídioENGENHARIAS::ENGENHARIA QUIMICAEstudo da oxidação preferencial do CO por catalisadores a base de irídioinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesis-1-13b275236-acc5-4218-a33b-8f802e7f5a18info:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSCARinstname:Universidade Federal de São Carlos (UFSCAR)instacron:UFSCARORIGINAL6304.pdfapplication/pdf1044370https://repositorio.ufscar.br/bitstream/ufscar/4152/1/6304.pdf10103e69b174c36a937b69eccfed4a96MD51TEXT6304.pdf.txt6304.pdf.txtExtracted texttext/plain0https://repositorio.ufscar.br/bitstream/ufscar/4152/2/6304.pdf.txtd41d8cd98f00b204e9800998ecf8427eMD52THUMBNAIL6304.pdf.jpg6304.pdf.jpgIM Thumbnailimage/jpeg6529https://repositorio.ufscar.br/bitstream/ufscar/4152/3/6304.pdf.jpga45da5b538781425761633ffa4c305a6MD53ufscar/41522023-09-18 18:31:33.765oai:repositorio.ufscar.br:ufscar/4152Repositório InstitucionalPUBhttps://repositorio.ufscar.br/oai/requestopendoar:43222023-09-18T18:31:33Repositório Institucional da UFSCAR - Universidade Federal de São Carlos (UFSCAR)false
dc.title.por.fl_str_mv Estudo da oxidação preferencial do CO por catalisadores a base de irídio
title Estudo da oxidação preferencial do CO por catalisadores a base de irídio
spellingShingle Estudo da oxidação preferencial do CO por catalisadores a base de irídio
Silva Júnior, Waldir da
Catálise
Oxidação preferencial
Irídio
ENGENHARIAS::ENGENHARIA QUIMICA
title_short Estudo da oxidação preferencial do CO por catalisadores a base de irídio
title_full Estudo da oxidação preferencial do CO por catalisadores a base de irídio
title_fullStr Estudo da oxidação preferencial do CO por catalisadores a base de irídio
title_full_unstemmed Estudo da oxidação preferencial do CO por catalisadores a base de irídio
title_sort Estudo da oxidação preferencial do CO por catalisadores a base de irídio
author Silva Júnior, Waldir da
author_facet Silva Júnior, Waldir da
author_role author
dc.contributor.authorlattes.por.fl_str_mv http://lattes.cnpq.br/0950063786043919
dc.contributor.author.fl_str_mv Silva Júnior, Waldir da
dc.contributor.advisor1.fl_str_mv Bueno, José Maria Corrêa
dc.contributor.advisor1Lattes.fl_str_mv http://lattes.cnpq.br/0157452280626031
dc.contributor.authorID.fl_str_mv 044d7216-4afb-4b52-bfcb-eb77a8049500
contributor_str_mv Bueno, José Maria Corrêa
dc.subject.por.fl_str_mv Catálise
Oxidação preferencial
Irídio
topic Catálise
Oxidação preferencial
Irídio
ENGENHARIAS::ENGENHARIA QUIMICA
dc.subject.cnpq.fl_str_mv ENGENHARIAS::ENGENHARIA QUIMICA
description Ir/Al2O3 samples were prepared to evaluate the influence of the particle size of the metal in the preferential oxidation of CO reaction. Initially, samples with different amounts of iridium were prepared in an attempt to get different particle sizes. Samples containing 1, 2, 6 and 10 % Ir/Al2O3 were prepared. The samples were prepared via dry impregnation, from alcoholic solutions of the salt precursor and calcined at a temperature of 400 °C. The -Al2O3 support was calcined at 550 °C. The catalytic tests were carried out using a flow rate of 100 ml/min of a mixture containing 1% O2, 1% CO, 45% H2 and balance in He. The results of XRD of these samples showed no characteristic peaks of iridium and the metal dispersions were very similar, raising the possibility that even with the increased loading of iridium samples showed no significant differences in their structure. After realize catalytic tests using the same density of active sites, it was found that the structure of the samples was very similar and the different results of activity and selectivity were due to the different densities of active sites. In order to obtain samples with different structural properties, was fixed in 4% the iridium concentration on the catalysts and was varied the calcination temperature of the catalysts (400, 550 and 750 °C) and the support (550 and 750 °C) and was studied the influence of calcination temperature of the catalyst as well the support. Results of XRD and hydrogen chemisorption showed large differences in particle size and metal dispersion. The total flow of the catalytic tests was reduced to 50 mL/min, maintaining the concentrations of the gases. DRIFTS spectra confirmed the structural differences due to the increase of calcination temperature of catalysts, showing a large decrease in the interaction between CO/metal. The results of the catalytic tests showed that by increasing the calcination temperature of the catalysts there is a loss of activity but these catalysts were more selective. A strong influence of the calcination temperature of the supports in the activity and selectivity of the catalysts was also observed. The results show that the PROX reaction is very sensitive to catalyst structure.
publishDate 2014
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2016-06-02T19:56:56Z
dc.date.issued.fl_str_mv 2014-03-31
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dc.identifier.citation.fl_str_mv SILVA JÚNIOR, Waldir da. Estudo da oxidação preferencial do CO por catalisadores a base de irídio. 2014. 70 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014.
dc.identifier.uri.fl_str_mv https://repositorio.ufscar.br/handle/ufscar/4152
identifier_str_mv SILVA JÚNIOR, Waldir da. Estudo da oxidação preferencial do CO por catalisadores a base de irídio. 2014. 70 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014.
url https://repositorio.ufscar.br/handle/ufscar/4152
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