Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.21/4924
Título: Catalytic behavior of alkali-treated Pt/HMOR n-hexane hydroisomerization
Autor: Monteiro, R.
Ania, Conchi O.
Rocha, J.
Carvalho, A. P.
Martins, Ângela Maria Pereira
Palavras-chave: MOR
Desilication
Bi-functional catalysts
Acidity
Platinum, n-Hexane Hydroisomerization
Data: 22-Abr-2014
Editora: Elsevier Science BV
Citação: MONTEIRO, R.; [et al] – Catalytic behavior of Alkali-Treated Pt/HMOR N-hexane hydroisomerization. Applied Catalysis A: General. ISSN: 0926-860X. Vol. 476 (2014), pp. 148-157
Resumo: 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,Al-27 and Si-29 MAS-NMR spectroscopy, N-2 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. (C) 2014 Elsevier B.V. All rights reserved.
Peer review: yes
URI: http://hdl.handle.net/10400.21/4924
DOI: 10.1016/j.apcata.2014.02.026
ISSN: 0926-860X
1873-3875
Versão do Editor: http://www.sciencedirect.com/science/article/pii/S0926860X1400115X#
Aparece nas colecções:ISEL - Eng. Quim. Biol. - Artigos

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