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Séminaire Chimie ED459 / Chaire Total

Zeolite-based hierarchical porous materials – controlled partial recrystallization and carbon templated synthesis approaches

Dr. Miroslaw Derewinski, Scientist (Institute of Integrated Catalysis, Pacific Northwest National Laboratory, Richland, WA, USA | Professeur Invité Chaire Total Balard)

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Le Jeudi 05 février 2015 à 13h45
UM Fac des Sciences, salle de cours SC-16.01 (campus Triolet)

High surface area, molecular dimensions of the pores, high sorption capacity, high homogeneity of the active sites impart zeolites with outstanding catalytic properties in huge number of reactions involving acid, base, bifunctional (acid-base, metal-acid, etc) and redox properties. In certain catalytic applications, however, the relatively small size of the microporous channels becomes a serious drawback as they impose steric constraints to the diffusion and/or access of reactants to the active sites, as well as to the formation and/or diffusion of target products. In order to overcome such mass transport limitations, among several strategies : (i) selective partial recrystallization of amorphous porous matrix and (ii) so-called carbon synthesis approach inducing mesoporosity in zeolites, can be employed.

With respect to first approach, the design, preparation and full characterization of composite materials containing dispersed zeolitic nanodomains will be presented. The main advantage of the new materials are : higher accessibility of active sites in obtained composites, shorter synthesis time and replacement of expensive zeolitic material by more available and less costly amorphous aluminosilicate materials. During the lecture results obtained on a standard aluminosilicate as well as on mesoporous solids will be presented and factors influencing formation of desired zeolitic phases (FAU, BEA) will be discussed.

Using carbon templating is an alternative approach inducing mesoporosity into zeolites. It will be shown that nearly uniform intracrystalline meso-voids can be generated by growing zeolite crystallites around carbon nanoparticles. They are mostly located inside the crystallites and are not directly accessible from the external zeolite surface. During the lecture, the improved catalytic performance of metal or metal sulfide loaded zeolites comprising intracrystalline mesopores in hydroconversion of n-octane and methane dehydroaromatization (MDA) will be described.

Contact local ICGM : Dr. François Fajula, D.R. CNRS (équipe MACS)


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