Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/243616
Type: Artigo
Title: Post-synthesis incorporation of Al into germanosilicate ITH zeolites: the influence of treatment conditions on the acidic properties and catalytic behavior in tetrahydropyranylation
Author: Shamzhy, Mariya V.
Opanasenko, Maksym V.
Ramos, Francisca S. de O.
Brabec, Libor
Horáček, Michal
Navarro-Rojas, Marta
Morris, Russell E.
Pastore, Heloise de O.
Čejka, Jiří
Abstract: Post-synthesis alumination of germanosilicate medium-pore ITH zeolites was shown to be an effective procedure for tuning their acidity. Treatment of ITH zeolites synthesized with different chemical compositions (i.e. Si/Ge = 2.5, 4.4 and 5.8) with aqueous Al(NO3)(3) solution led to the formation of strong Bronsted and Lewis acid sites and an increasing fraction of ultramicro- and meso-pores in Ge-rich ITH samples (Si/Ge = 2.5 and 4.4). The concentration of Al incorporated into the framework increases with decreasing Si/Ge ratio of the parent ITH. The increasing temperature of alumination from 80 to 175 degrees C (HT conditions) resulted in (1) a 1.5-2-fold increase in the concentration of Bronsted acid sites formed and (2) a decreasing fraction of framework Al atoms detectable with base probe molecules (i.e. pyridine, 2,6-di-tert-butylpyridine), i.e. an increased concentration of the "inner" acid sites. The activity of prepared Al-substituted ITH zeolites in tetrahydropyranylation of alcohols is enhanced with increasing amount of accessible acid sites in bulky crystals (e.g. alumination at lower temperature) or with increasing total concentration of acid centres within tiny ITH crystals (e.g. alumination under HT conditions). This trend became more prominent with increasing kinetic diameter of the substrate molecules under investigation (methanol < 1-propanol < 1-hexanol).
Post-synthesis alumination of germanosilicate medium-pore ITH zeolites was shown to be an effective procedure for tuning their acidity. Treatment of ITH zeolites synthesized with different chemical compositions (i.e.Si/Ge = 2.5, 4.4 and 5.8) with aqueous
Subject: Alumínio
Zeolitos
Acidez
Catálise
Country: Reino Unido
Editor: Royal Society of Chemistry
Citation: Post-synthesis Incorporation Of Al Into Germanosilicate Ith Zeolites: The Influence Of Treatment Conditions On The Acidic Properties And Catalytic Behavior In Tetrahydropyranylation. Royal Soc Chemistry, v. 5, p. 2973-2984 2015.
Rights: aberto
Identifier DOI: 10.1039/C4CY01594K
Address: https://pubs.rsc.org/en/content/articlelanding/2015/cy/c4cy01594k
Date Issue: 2015
Appears in Collections:IQ - Artigos e Outros Documentos

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