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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

2 D CFM images of Z80‐Si reacted with thiophene and impregnated with Nile blue chloride. Simultaneous excitation with 488 and 642 nm lasers produced a green fluorescence attributed to ZSM‐5 domains with surrounding binder producing a red fluorescence. Enlargement of the marked area in the left image is shown on the right.
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fig7: 2 D CFM images of Z80‐Si reacted with thiophene and impregnated with Nile blue chloride. Simultaneous excitation with 488 and 642 nm lasers produced a green fluorescence attributed to ZSM‐5 domains with surrounding binder producing a red fluorescence. Enlargement of the marked area in the left image is shown on the right.

Mentions: To confirm that the surrounding area of ZSM‐5 crystals/agglomerates is indeed binder material, a separate experiment using both thiophene and Nile blue chloride43 on Z80‐Si was performed. Owing to the large molecular dimensions of Nile blue chloride, it is unable to fit inside the zeolite pores and therefore only occupies the binder. By exciting Z80‐Si with both 488 and 642 nm lasers, both these compounds can be excited to determine the distribution of active phase and binder. In Figure 7, the location of fluorescent green ZSM‐5 domains is illustrated, which are closely surrounded by SiO2, which emits a red fluorescence. This result confirms the close proximity of the binder material to the ZSM‐5 domains, which can allow the growth of oligomer species off the surface of the ZSM‐5 crystals into the binder, leading to optical absorption band shifts.


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)

2 D CFM images of Z80‐Si reacted with thiophene and impregnated with Nile blue chloride. Simultaneous excitation with 488 and 642 nm lasers produced a green fluorescence attributed to ZSM‐5 domains with surrounding binder producing a red fluorescence. Enlargement of the marked area in the left image is shown on the right.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4834610&req=5

fig7: 2 D CFM images of Z80‐Si reacted with thiophene and impregnated with Nile blue chloride. Simultaneous excitation with 488 and 642 nm lasers produced a green fluorescence attributed to ZSM‐5 domains with surrounding binder producing a red fluorescence. Enlargement of the marked area in the left image is shown on the right.
Mentions: To confirm that the surrounding area of ZSM‐5 crystals/agglomerates is indeed binder material, a separate experiment using both thiophene and Nile blue chloride43 on Z80‐Si was performed. Owing to the large molecular dimensions of Nile blue chloride, it is unable to fit inside the zeolite pores and therefore only occupies the binder. By exciting Z80‐Si with both 488 and 642 nm lasers, both these compounds can be excited to determine the distribution of active phase and binder. In Figure 7, the location of fluorescent green ZSM‐5 domains is illustrated, which are closely surrounded by SiO2, which emits a red fluorescence. This result confirms the close proximity of the binder material to the ZSM‐5 domains, which can allow the growth of oligomer species off the surface of the ZSM‐5 crystals into the binder, leading to optical absorption band shifts.

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