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

Whiting GT, Meirer F, Mertens MM, Bons AJ, Weiss BM, Stevens PA, de Smit E, Weckhuysen BM - ChemCatChem (2015)

Bottom Line: It was found that aluminium migration occurs in ZSM-5-containing Al2O3-bound extrudates, forming additional Brønsted acid sites.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.

View Article: PubMed Central - PubMed

Affiliation: Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht (The Netherlands).

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus

3 D CFM images of a) volume of Z80‐Si excited with 488 nm laser, showing fluorescent green oligomers present in ZSM‐5 crystals/agglomerates; b) same volume as in (a), excited simultaneously with 488 and 561 nm laser, showing the growth of larger oligomers off the surface of ZSM‐5 crystals/agglomerates.
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fig6: 3 D CFM images of a) volume of Z80‐Si excited with 488 nm laser, showing fluorescent green oligomers present in ZSM‐5 crystals/agglomerates; b) same volume as in (a), excited simultaneously with 488 and 561 nm laser, showing the growth of larger oligomers off the surface of ZSM‐5 crystals/agglomerates.

Mentions: In contrast, for Z50‐Si and Z20‐Si the band attributed to four‐thiophene ring oligomers (E) bathochromically shifts from 550 to 560 nm. It is highly plausible that these larger molecules grow off the surface of ZSM‐5 crystals/agglomerates into the surrounding binder. Evidence of this is visualised by 3 D images obtained by CFM and thiophene oligomerisation reaction. In Figure 6 a, the 2–6 μm fluorescent green domains are displayed, the locations of which are consistent with the morphology of ZSM‐5 crystals/agglomerates (Figure S1 a), containing oligomer species (compounds F) that absorb light at 488 nm. The additional use of a 561 nm laser (whilst simultaneously employing a 488 nm laser) demonstrates that these larger red fluorescent conjugated/extended species (E) appear to grow off the surface of ZSM‐5 crystals/agglomerates into the SiO2 binder (Figure 6 b).


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

Whiting GT, Meirer F, Mertens MM, Bons AJ, Weiss BM, Stevens PA, de Smit E, Weckhuysen BM - ChemCatChem (2015)

3 D CFM images of a) volume of Z80‐Si excited with 488 nm laser, showing fluorescent green oligomers present in ZSM‐5 crystals/agglomerates; b) same volume as in (a), excited simultaneously with 488 and 561 nm laser, showing the growth of larger oligomers off the surface of ZSM‐5 crystals/agglomerates.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4834610&req=5

fig6: 3 D CFM images of a) volume of Z80‐Si excited with 488 nm laser, showing fluorescent green oligomers present in ZSM‐5 crystals/agglomerates; b) same volume as in (a), excited simultaneously with 488 and 561 nm laser, showing the growth of larger oligomers off the surface of ZSM‐5 crystals/agglomerates.
Mentions: In contrast, for Z50‐Si and Z20‐Si the band attributed to four‐thiophene ring oligomers (E) bathochromically shifts from 550 to 560 nm. It is highly plausible that these larger molecules grow off the surface of ZSM‐5 crystals/agglomerates into the surrounding binder. Evidence of this is visualised by 3 D images obtained by CFM and thiophene oligomerisation reaction. In Figure 6 a, the 2–6 μm fluorescent green domains are displayed, the locations of which are consistent with the morphology of ZSM‐5 crystals/agglomerates (Figure S1 a), containing oligomer species (compounds F) that absorb light at 488 nm. The additional use of a 561 nm laser (whilst simultaneously employing a 488 nm laser) demonstrates that these larger red fluorescent conjugated/extended species (E) appear to grow off the surface of ZSM‐5 crystals/agglomerates into the SiO2 binder (Figure 6 b).

Bottom Line: It was found that aluminium migration occurs in ZSM-5-containing Al2O3-bound extrudates, forming additional Brønsted acid sites.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.

View Article: PubMed Central - PubMed

Affiliation: Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht (The Netherlands).

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus