Binder Effects in SiO2- and Al2O3-Bound Zeolite ZSM-5-Based Extrudates as Studied by Microspectroscopy.

Autor: Whiting, Gareth T., Meirer, Florian, Mertens, Machteld M., Bons, Anton‐Jan, Weiss, Brian M., Stevens, Paul A., de Smit, Emiel, Weckhuysen, Bert M.
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Zdroj: ChemCatChem; Apr2015, Vol. 7 Issue 8, p1312-1321, 10p
Abstrakt: Microspectroscopic methods were explored to investigate binder effects occurring in ZSM-5-containing SiO2- and Al2O3-bound millimetre-sized extrudates. Using thiophene as a selective probe for Brønsted acidity, coupled with time-resolved in situ UV/Vis and confocal fluorescence microspectroscopy, variations in reactivity and selectivity between the two distinct binder types were established. It was found that aluminium migration occurs in ZSM-5-containing Al2O3-bound extrudates, forming additional Brønsted acid sites. These sites strongly influence the oligomer selectivity, favouring the formation of thiol-like species (i.e., ring-opened species) in contrast to higher oligomers, predominantly formed on SiO2-bound ZSM-5-containing extrudates. Not only were the location and distribution of these oligomers visualised by 3 D analysis, it was also observed that more conjugated species appeared to grow off the surface of the zeolite ZSM-5 crystals (containing less conjugated species) into the surrounding binder material. Furthermore, a higher binder content resulted in an increasing overall reactivity owing to the greater number of stored thiophene monomers available per Brønsted acid site. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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