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Al-containing MCM-41 type materials prepared by different synthesis methods: hydrothermal stability and catalytic properties
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Advisor(s)
Abstract(s)
Al-containing MCM-41 type materials were prepared by three different synthesis methods
(aluminum grafting on the calcined MCM-41, pH adjustment during the crystallization period
and crystallization in the presence of zeolite seeds). The samples were characterized by
powder XRD, nitrogen adsorption, 27Al MAS NMR and FTIR with pyridine as probe
molecule. All the samples exhibit a high hydrothermal stability at high temperature just with a
minor structural degradation. N2 adsorption data obtained for the sample prepared from a gel
containing zeolite seeds suggest a higher structural resistance to the hydrothermal treatment in
comparison with the samples prepared by other methods. A different type of pyridine
adsorbed, probably interacting simultaneously with a Brönsted and a Lewis acid site, is
observed upon pyridine adsorption. This type of adsorption is stronger for the sample
prepared in the presence of zeolite seeds and is not observed on Al-grafted MCM-41.
2
The catalytic activity towards the isomerization of α-pinene depends mainly on the number of
Brönsted acid sites. The data obtained in this study strongly indicate that for this type of
materials, the Lewis acid sites do not influence the selectivity for the isomerization products.
Description
Keywords
Alpha-pinene MCM-41 Synthesis Hydrothermal stability Catalytic activity
Pedagogical Context
Citation
Lourenço, J. P.; Fernandes, A.; Henriques, C.; Ribeiro, M.F. Al-containing MCM-41 type materials prepared by different synthesis methods: hydrothermal stability and catalytic properties. Microporous and Mesoporous Materials, 94, 56-65, 2006.