Liquid crystals as pore template for sulfated zirconia
Autor(a) principal: | |
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Data de Publicação: | 2020 |
Outros Autores: | , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UNESP |
Texto Completo: | http://hdl.handle.net/11449/197827 |
Resumo: | Porous sulfated zirconia was prepared using a sol-gel process associated with liquid crystal templates (LCTs). Evaluation was made of the e ffects of the Zr 4+ :SO 4 2 - molar ratio and aging time on the formation and stability of the lyotropic arrangement of the LCT gel and the features of the resulting mesoporous powders. Polarized light microscopy and small -angle X-ray di ffraction (SAXD) analysis of the LCT gel revealed the prevalence of hex- agonal mesophase ( P6mm ) in the sulfated samples. Thermal treatment of the samples resulted in sulfated ZrO 2 ceramic powders whose infrared spectra exhibited bands characteristic of mono- and bi-dentate SO 4 2 - groups bonded to ZrO 2 . X -Ray di ffractograms of the materials showed a mixture of monoclinic and tetragonal phases of zirconia, with the tetragonal phase increasing from 86 -90% to 100% as the Zr 4+ :SO 4 2 - molar ratio decreases from 15 to 5. Crystallite sizes of about 9.5 and 4.5 nm were observed for the pristine and sulfated zirconia (Zr 4+ :SO 4 2 - = 5), respectively. The lattice fringe distances observed for selected areas in the electron di ffrac- tion patterns and in high -resolution transmission electron micrographs con firmed the mixture of tetragonal and monoclinic crystalline phases. Small -angle X -Ray scattering analysis showed that the gyration radius was around 2 nm and that the particles were organized as a branched network with a fractal surface when sulfate was inserted in the zirconia structure, improving its porous characteristics. The LCT generated pores with greater diameters (up to 4.4 nm) in the sulfated samples, while the surface area increased to 146 m 2 g -1 . The gel aging process led to the reinforcement of the pore wall structure, prevented shrinkage e ffects during calcination, and enabled higher surface areas to be achieved. Scanning and transmission electron microscopy analyses showed that the walls of the pores were composed of platelets of irregular shapes, giving rise to mesopores. The porous structure, combined with the presence of acid sites, improved by sulfate groups at the surface of tetragonal zirconia crystallite, makes these materials promising candidates for application as catalysts in dehydration re- actions. |
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Liquid crystals as pore template for sulfated zirconiaSulfated zirconiaLiquid crystal templatePorous materialsSol-gel processCatalystPorous sulfated zirconia was prepared using a sol-gel process associated with liquid crystal templates (LCTs). Evaluation was made of the e ffects of the Zr 4+ :SO 4 2 - molar ratio and aging time on the formation and stability of the lyotropic arrangement of the LCT gel and the features of the resulting mesoporous powders. Polarized light microscopy and small -angle X-ray di ffraction (SAXD) analysis of the LCT gel revealed the prevalence of hex- agonal mesophase ( P6mm ) in the sulfated samples. Thermal treatment of the samples resulted in sulfated ZrO 2 ceramic powders whose infrared spectra exhibited bands characteristic of mono- and bi-dentate SO 4 2 - groups bonded to ZrO 2 . X -Ray di ffractograms of the materials showed a mixture of monoclinic and tetragonal phases of zirconia, with the tetragonal phase increasing from 86 -90% to 100% as the Zr 4+ :SO 4 2 - molar ratio decreases from 15 to 5. Crystallite sizes of about 9.5 and 4.5 nm were observed for the pristine and sulfated zirconia (Zr 4+ :SO 4 2 - = 5), respectively. The lattice fringe distances observed for selected areas in the electron di ffrac- tion patterns and in high -resolution transmission electron micrographs con firmed the mixture of tetragonal and monoclinic crystalline phases. Small -angle X -Ray scattering analysis showed that the gyration radius was around 2 nm and that the particles were organized as a branched network with a fractal surface when sulfate was inserted in the zirconia structure, improving its porous characteristics. The LCT generated pores with greater diameters (up to 4.4 nm) in the sulfated samples, while the surface area increased to 146 m 2 g -1 . The gel aging process led to the reinforcement of the pore wall structure, prevented shrinkage e ffects during calcination, and enabled higher surface areas to be achieved. Scanning and transmission electron microscopy analyses showed that the walls of the pores were composed of platelets of irregular shapes, giving rise to mesopores. The porous structure, combined with the presence of acid sites, improved by sulfate groups at the surface of tetragonal zirconia crystallite, makes these materials promising candidates for application as catalysts in dehydration re- actions.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)National Institute of Science and Technology on Advanced EcoEfficient Cement-Based Technologies (INCT grant)Sao Paulo State Univ UNESP, Inst Chem, BR-14800060 Araraquara, SP, BrazilSao Paulo State Univ UNESP, Inst Chem, BR-14800060 Araraquara, SP, BrazilCNPq: 304900/2011-7CNPq: 430758/2018-9CNPq: 150427/2015-8CAPES: 001National Institute of Science and Technology on Advanced EcoEfficient Cement-Based Technologies (INCT grant): 14/50948-3National Institute of Science and Technology on Advanced EcoEfficient Cement-Based Technologies (INCT grant): 14/465593-3Elsevier B.V.Universidade Estadual Paulista (Unesp)Moris, Carlos Henrique A. A. [UNESP]Alves-Rosa, Marinalva A. [UNESP]Freitas, Fernanda G. [UNESP]Martins, Leandro [UNESP]Santilli, Celso [UNESP]Pulcinelli, Sandra H. [UNESP]2020-12-11T20:53:15Z2020-12-11T20:53:15Z2020-09-05info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/article10Colloids And Surfaces A-physicochemical And Engineering Aspects. Amsterdam: Elsevier, v. 600, 10 p., 2020.0927-7757http://hdl.handle.net/11449/197827WOS:00054292520000955842986818708650000-0002-8356-8093Web of Sciencereponame:Repositório Institucional da UNESPinstname:Universidade Estadual Paulista (UNESP)instacron:UNESPengColloids And Surfaces A-physicochemical And Engineering Aspectsinfo:eu-repo/semantics/openAccess2021-10-23T15:09:23Zoai:repositorio.unesp.br:11449/197827Repositório InstitucionalPUBhttp://repositorio.unesp.br/oai/requestopendoar:29462024-08-05T23:50:24.583401Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)false |
dc.title.none.fl_str_mv |
Liquid crystals as pore template for sulfated zirconia |
title |
Liquid crystals as pore template for sulfated zirconia |
spellingShingle |
Liquid crystals as pore template for sulfated zirconia Moris, Carlos Henrique A. A. [UNESP] Sulfated zirconia Liquid crystal template Porous materials Sol-gel process Catalyst |
title_short |
Liquid crystals as pore template for sulfated zirconia |
title_full |
Liquid crystals as pore template for sulfated zirconia |
title_fullStr |
Liquid crystals as pore template for sulfated zirconia |
title_full_unstemmed |
Liquid crystals as pore template for sulfated zirconia |
title_sort |
Liquid crystals as pore template for sulfated zirconia |
author |
Moris, Carlos Henrique A. A. [UNESP] |
author_facet |
Moris, Carlos Henrique A. A. [UNESP] Alves-Rosa, Marinalva A. [UNESP] Freitas, Fernanda G. [UNESP] Martins, Leandro [UNESP] Santilli, Celso [UNESP] Pulcinelli, Sandra H. [UNESP] |
author_role |
author |
author2 |
Alves-Rosa, Marinalva A. [UNESP] Freitas, Fernanda G. [UNESP] Martins, Leandro [UNESP] Santilli, Celso [UNESP] Pulcinelli, Sandra H. [UNESP] |
author2_role |
author author author author author |
dc.contributor.none.fl_str_mv |
Universidade Estadual Paulista (Unesp) |
dc.contributor.author.fl_str_mv |
Moris, Carlos Henrique A. A. [UNESP] Alves-Rosa, Marinalva A. [UNESP] Freitas, Fernanda G. [UNESP] Martins, Leandro [UNESP] Santilli, Celso [UNESP] Pulcinelli, Sandra H. [UNESP] |
dc.subject.por.fl_str_mv |
Sulfated zirconia Liquid crystal template Porous materials Sol-gel process Catalyst |
topic |
Sulfated zirconia Liquid crystal template Porous materials Sol-gel process Catalyst |
description |
Porous sulfated zirconia was prepared using a sol-gel process associated with liquid crystal templates (LCTs). Evaluation was made of the e ffects of the Zr 4+ :SO 4 2 - molar ratio and aging time on the formation and stability of the lyotropic arrangement of the LCT gel and the features of the resulting mesoporous powders. Polarized light microscopy and small -angle X-ray di ffraction (SAXD) analysis of the LCT gel revealed the prevalence of hex- agonal mesophase ( P6mm ) in the sulfated samples. Thermal treatment of the samples resulted in sulfated ZrO 2 ceramic powders whose infrared spectra exhibited bands characteristic of mono- and bi-dentate SO 4 2 - groups bonded to ZrO 2 . X -Ray di ffractograms of the materials showed a mixture of monoclinic and tetragonal phases of zirconia, with the tetragonal phase increasing from 86 -90% to 100% as the Zr 4+ :SO 4 2 - molar ratio decreases from 15 to 5. Crystallite sizes of about 9.5 and 4.5 nm were observed for the pristine and sulfated zirconia (Zr 4+ :SO 4 2 - = 5), respectively. The lattice fringe distances observed for selected areas in the electron di ffrac- tion patterns and in high -resolution transmission electron micrographs con firmed the mixture of tetragonal and monoclinic crystalline phases. Small -angle X -Ray scattering analysis showed that the gyration radius was around 2 nm and that the particles were organized as a branched network with a fractal surface when sulfate was inserted in the zirconia structure, improving its porous characteristics. The LCT generated pores with greater diameters (up to 4.4 nm) in the sulfated samples, while the surface area increased to 146 m 2 g -1 . The gel aging process led to the reinforcement of the pore wall structure, prevented shrinkage e ffects during calcination, and enabled higher surface areas to be achieved. Scanning and transmission electron microscopy analyses showed that the walls of the pores were composed of platelets of irregular shapes, giving rise to mesopores. The porous structure, combined with the presence of acid sites, improved by sulfate groups at the surface of tetragonal zirconia crystallite, makes these materials promising candidates for application as catalysts in dehydration re- actions. |
publishDate |
2020 |
dc.date.none.fl_str_mv |
2020-12-11T20:53:15Z 2020-12-11T20:53:15Z 2020-09-05 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
Colloids And Surfaces A-physicochemical And Engineering Aspects. Amsterdam: Elsevier, v. 600, 10 p., 2020. 0927-7757 http://hdl.handle.net/11449/197827 WOS:000542925200009 5584298681870865 0000-0002-8356-8093 |
identifier_str_mv |
Colloids And Surfaces A-physicochemical And Engineering Aspects. Amsterdam: Elsevier, v. 600, 10 p., 2020. 0927-7757 WOS:000542925200009 5584298681870865 0000-0002-8356-8093 |
url |
http://hdl.handle.net/11449/197827 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
Colloids And Surfaces A-physicochemical And Engineering Aspects |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
10 |
dc.publisher.none.fl_str_mv |
Elsevier B.V. |
publisher.none.fl_str_mv |
Elsevier B.V. |
dc.source.none.fl_str_mv |
Web of Science reponame:Repositório Institucional da UNESP instname:Universidade Estadual Paulista (UNESP) instacron:UNESP |
instname_str |
Universidade Estadual Paulista (UNESP) |
instacron_str |
UNESP |
institution |
UNESP |
reponame_str |
Repositório Institucional da UNESP |
collection |
Repositório Institucional da UNESP |
repository.name.fl_str_mv |
Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP) |
repository.mail.fl_str_mv |
|
_version_ |
1808129558030843904 |