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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

Microspectroscopic analysis of aluminium migration in silicalite‐containing Al2O3‐bound extrudates. a, d) Filtered in situ optical absorption time series spectra during thiophene oligomerisation over Sil80‐Al and Sil20‐Al, respectively. Corresponding 3 D top‐view CFM images of b, c) Sil80‐Al and e, f) Sil20‐Al, excited with b, e) 488 nm laser and c, f) 561 nm laser.
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fig5: Microspectroscopic analysis of aluminium migration in silicalite‐containing Al2O3‐bound extrudates. a, d) Filtered in situ optical absorption time series spectra during thiophene oligomerisation over Sil80‐Al and Sil20‐Al, respectively. Corresponding 3 D top‐view CFM images of b, c) Sil80‐Al and e, f) Sil20‐Al, excited with b, e) 488 nm laser and c, f) 561 nm laser.

Mentions: The optical absorption spectra of Sil80‐Al are illustrated in Figure 5 a. Strikingly, a relatively high reactivity is obtained, clearly demonstrating that Brønsted acid sites have been formed during preparation. As with the ZSM‐5‐based extrudates, bands at 410 and 485 nm are formed. However, the absence of a band at 550 nm (compound E), coupled with the appearance of a band at 440 nm (F2), suggests the favouring of the ring‐opening reaction pathway to the further oligomerisation route. In Figure 5 b and c, the location of such fluorescent oligomer species formed on acid sites in the silicalite structure in 3 D is visualised by using CFM (employing 488 and 561 nm lasers, respectively).


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)

Microspectroscopic analysis of aluminium migration in silicalite‐containing Al2O3‐bound extrudates. a, d) Filtered in situ optical absorption time series spectra during thiophene oligomerisation over Sil80‐Al and Sil20‐Al, respectively. Corresponding 3 D top‐view CFM images of b, c) Sil80‐Al and e, f) Sil20‐Al, excited with b, e) 488 nm laser and c, f) 561 nm laser.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4834610&req=5

fig5: Microspectroscopic analysis of aluminium migration in silicalite‐containing Al2O3‐bound extrudates. a, d) Filtered in situ optical absorption time series spectra during thiophene oligomerisation over Sil80‐Al and Sil20‐Al, respectively. Corresponding 3 D top‐view CFM images of b, c) Sil80‐Al and e, f) Sil20‐Al, excited with b, e) 488 nm laser and c, f) 561 nm laser.
Mentions: The optical absorption spectra of Sil80‐Al are illustrated in Figure 5 a. Strikingly, a relatively high reactivity is obtained, clearly demonstrating that Brønsted acid sites have been formed during preparation. As with the ZSM‐5‐based extrudates, bands at 410 and 485 nm are formed. However, the absence of a band at 550 nm (compound E), coupled with the appearance of a band at 440 nm (F2), suggests the favouring of the ring‐opening reaction pathway to the further oligomerisation route. In Figure 5 b and c, the location of such fluorescent oligomer species formed on acid sites in the silicalite structure in 3 D is visualised by using CFM (employing 488 and 561 nm lasers, respectively).

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