Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization

Bifunctional Pt-HMOR catalysts were prepared by incipient wetness impregnation of various desilicated MOR obtained by alkaline treatment using NaOH concentrations ranging from 0.1 to 0.5 M. The zeolite structural changes upon modification were investigated by several techniques including powder X-ra...

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Autores: Monteiro, R., Ovín Ania, María Concepción, Rocha, J., Carvalho, A.P., Martins, A.
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2014
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/99594
Acceso en línea:http://hdl.handle.net/10261/99594
Access Level:acceso abierto
Palabra clave:MOR
Desilication
Bi-functional catalysts
Acidity
Platinum
n-Hexane hydroisomerization
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spelling Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerizationMonteiro, R.Ovín Ania, María ConcepciónRocha, J.Carvalho, A.P.Martins, A.MORDesilicationBi-functional catalystsAcidityPlatinumn-Hexane hydroisomerizationBifunctional Pt-HMOR catalysts were prepared by incipient wetness impregnation of various desilicated MOR obtained by alkaline treatment using NaOH concentrations ranging from 0.1 to 0.5 M. The zeolite structural changes upon modification were investigated by several techniques including powder X-ray diffraction, 27Al and 29Si MAS-NMR spectroscopy, N2 adsorption, pyridine adsorption followed by infrared spectroscopy and the catalytic model reaction of m-xylene transformation. For low alkaline concentration the zeolite acidity is preserved, along with a slight increase of the volume correspondent to the larger micropores due to the removal of extra-framework debris already existent at the parent zeolite. At higher NaOH concentrations there is a significant loss of crystalinity and acidity as well as the formation of mesoporosity. The characterization of the metal function shows similar patterns for Pt-HMOR and Pt-M/0.1 samples, with Pt particles located mainly inside the inner porosity. In contrast, large Pt particles become visible at the intercrystalline mesoporosity of MOR crystals developed during the desilication treatments at severe alkaline conditions. The catalytic results obtained for n-hexane hydroisomerization showed an improved selectivity for dibranched over monobranched isomers for Pt-M/0.1 sample, likely due to the preservation of the support acidity and the slight enlargement of the micropores. This work is a new example in which the mesoporous development does not improve the catalytic efficiency of the zeolites, whereas mild alkaline desilication might be considered as an effective solution to produce customized catalysts with enhanced performance for a given application.This work was financially supported by FCT (Portugal) through strategic projects PEst- OE/QUI/UI0612/2013 (CQB), and PEst-C/CTM/LA0011/2013, Portuguese NMR Network (RNRMN)Peer reviewedElsevierConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]201420142014info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Postprintinfo:eu-repo/semantics/acceptedVersionhttp://hdl.handle.net/10261/99594reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Españolhttp://dx.doi.org/10.1016/j.apcata.2014.02.026Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/995942026-05-22T06:33:51Z
dc.title.none.fl_str_mv Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
title Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
spellingShingle Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
Monteiro, R.
MOR
Desilication
Bi-functional catalysts
Acidity
Platinum
n-Hexane hydroisomerization
title_short Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
title_full Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
title_fullStr Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
title_full_unstemmed Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
title_sort Catalytic behavior of alkali-treated Pt/HMOR in n-hexane hydroisomerization
dc.creator.none.fl_str_mv Monteiro, R.
Ovín Ania, María Concepción
Rocha, J.
Carvalho, A.P.
Martins, A.
author Monteiro, R.
author_facet Monteiro, R.
Ovín Ania, María Concepción
Rocha, J.
Carvalho, A.P.
Martins, A.
author_role author
author2 Ovín Ania, María Concepción
Rocha, J.
Carvalho, A.P.
Martins, A.
author2_role author
author
author
author
dc.contributor.none.fl_str_mv Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv MOR
Desilication
Bi-functional catalysts
Acidity
Platinum
n-Hexane hydroisomerization
topic MOR
Desilication
Bi-functional catalysts
Acidity
Platinum
n-Hexane hydroisomerization
description Bifunctional Pt-HMOR catalysts were prepared by incipient wetness impregnation of various desilicated MOR obtained by alkaline treatment using NaOH concentrations ranging from 0.1 to 0.5 M. The zeolite structural changes upon modification were investigated by several techniques including powder X-ray diffraction, 27Al and 29Si MAS-NMR spectroscopy, N2 adsorption, pyridine adsorption followed by infrared spectroscopy and the catalytic model reaction of m-xylene transformation. For low alkaline concentration the zeolite acidity is preserved, along with a slight increase of the volume correspondent to the larger micropores due to the removal of extra-framework debris already existent at the parent zeolite. At higher NaOH concentrations there is a significant loss of crystalinity and acidity as well as the formation of mesoporosity. The characterization of the metal function shows similar patterns for Pt-HMOR and Pt-M/0.1 samples, with Pt particles located mainly inside the inner porosity. In contrast, large Pt particles become visible at the intercrystalline mesoporosity of MOR crystals developed during the desilication treatments at severe alkaline conditions. The catalytic results obtained for n-hexane hydroisomerization showed an improved selectivity for dibranched over monobranched isomers for Pt-M/0.1 sample, likely due to the preservation of the support acidity and the slight enlargement of the micropores. This work is a new example in which the mesoporous development does not improve the catalytic efficiency of the zeolites, whereas mild alkaline desilication might be considered as an effective solution to produce customized catalysts with enhanced performance for a given application.
publishDate 2014
dc.date.none.fl_str_mv 2014
2014
2014
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Postprint
info:eu-repo/semantics/acceptedVersion
format article
status_str acceptedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/99594
url http://hdl.handle.net/10261/99594
dc.language.none.fl_str_mv Español
language_invalid_str_mv Español
dc.relation.none.fl_str_mv http://dx.doi.org/10.1016/j.apcata.2014.02.026
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Elsevier
publisher.none.fl_str_mv Elsevier
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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