Composite SBA-15/MFI Type Materials: Preparation, Characterization and Catalytic Performance

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Composite SBA-15/MFI Type Materials: Preparation, Characterization and Catalytic Performance Veronika Pashkova Æ Ewa Włoch Æ Andrzej Mikołajczyk Æ Marek Łaniecki Æ Bogdan Sulikowski Æ Mirosław Derewin´ski

Received: 30 July 2008 / Accepted: 26 September 2008 / Published online: 11 November 2008 Ó Springer Science+Business Media, LLC 2008

Abstract SBA-15 type mesoporous molecular sieve was prepared and used as a parent material for synthesis of a SBA-15/zeolite composite. Thus, after addition of an aluminum source into the pristine sample, it was subjected to recrystallization in the water-vapor phase to give the SBA15/MFI composites. The samples obtained were characterized by XRD, nitrogen sorption, scanning and transmission electron microscopies, 27Al MAS NMR and FT IR. The materials after recrystallization retained their mesoporous character. Characteristics of the material revealed that all the aluminum added was inserted into the final hybrid. As shown by FT IR and NMR, at least some of aluminum was introduced into the nanoparticles of MFI and adopted fourfold coordination, typical for zeolites. Formation of Brønsted acid centres was directly confirmed by IR studies. The catalytic activity was screened in the liquid-phase isomerization of a-pinene. The main products of a-pinene transformations were camphene, limonene and c-terpinene. The overall selectivity toward camphene ? limonene was ca. 90%. Taking into account the low amount of the MFI phase present in a composite sample, calculated initial reaction rate was comparable with other catalytic systems explored in the isomerization of a-pinene.

The work was presented during the conference ‘Catalysis for Society’, Krakow, May 11–15, 2008. V. Pashkova  E. Włoch  B. Sulikowski  M. Derewin´ski (&) Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krako´w, Poland e-mail: [email protected] A. Mikołajczyk  M. Łaniecki Department of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan´, Poland

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Keywords SBA-15  MFI  Composite materials  Porosity  Acidity  Isomerization of a-pinene

1 Introduction Microporous zeolites (i.e., crystalline aluminosilicates) are a class of materials which focused great attention in the last half century. There are 179 zeolites known, and the list is growing constantly. Their importance stems from the two features: they are characterized by unique architecture of the relatively rigid framework, coupled with the presence of (predominately) Brønsted acid centres. Properly modified zeolites are strong solid acids. However, at variance with other solid-state acids known, for example heteropoly acids [1], the architecture of zeolites gives rise to various pore/cavity systems [2]. These free volumes are occupied by zeolitic water and inorganic and/or organic cations, neutralizing the negative charge of the framework. Upon water removal, the inner space of zeolites becomes available for deposition of species, exerting or modifying catalytic properties. Zeolites are