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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

Pore‐volume distributions, determined by the Barrett–Joyner–Halenda adsorption method with N2, for: a) a series of ZSM‐5‐containing SiO2‐bound extrudates and b) a series of ZSM‐5‐containing Al2O3‐bound extrudates.
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fig1: Pore‐volume distributions, determined by the Barrett–Joyner–Halenda adsorption method with N2, for: a) a series of ZSM‐5‐containing SiO2‐bound extrudates and b) a series of ZSM‐5‐containing Al2O3‐bound extrudates.

Mentions: Evidently, the increase in content of both binder types corresponds with an increase in overall pore volume (i.e., the pore volume of Z80‐Si, 0.35 cm3 g−1, is smaller than that of Z20‐Si, 0.70 cm3 g−1, Table 1). However, the predicted pore volumes (calculation based on those of the pure components) of the ZSM‐5:binder‐bound extrudates are significantly higher than the experimentally determined ones. Particularly in the case of the SiO2‐bound samples, as much as a 21 % decrease was measured for Z20‐Si, with the Al2O3‐bound samples observing the same trend but to a lower extent (Z20‐Al, 11 % decrease). This exemplifies the changes induced upon combining both the active zeolite phase and the binder material in extrudates, with the decrease in pore volume attributed to blockage/coverage of the binder pores with ZSM‐5 crystals/agglomerates and/or morphological changes in the binder. Corresponding pore‐size distributions are illustrated in Figure 1. Noticeably, the ZSM‐5‐based SiO2‐bound extrudates express a far wider pore‐size distribution than their Al2O3‐bound counterparts. An increase in active‐phase content creates a narrower pore‐size distribution in both cases, owing to the lower contribution of mesopores from the decreased binder content.


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)

Pore‐volume distributions, determined by the Barrett–Joyner–Halenda adsorption method with N2, for: a) a series of ZSM‐5‐containing SiO2‐bound extrudates and b) a series of ZSM‐5‐containing Al2O3‐bound extrudates.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: Pore‐volume distributions, determined by the Barrett–Joyner–Halenda adsorption method with N2, for: a) a series of ZSM‐5‐containing SiO2‐bound extrudates and b) a series of ZSM‐5‐containing Al2O3‐bound extrudates.
Mentions: Evidently, the increase in content of both binder types corresponds with an increase in overall pore volume (i.e., the pore volume of Z80‐Si, 0.35 cm3 g−1, is smaller than that of Z20‐Si, 0.70 cm3 g−1, Table 1). However, the predicted pore volumes (calculation based on those of the pure components) of the ZSM‐5:binder‐bound extrudates are significantly higher than the experimentally determined ones. Particularly in the case of the SiO2‐bound samples, as much as a 21 % decrease was measured for Z20‐Si, with the Al2O3‐bound samples observing the same trend but to a lower extent (Z20‐Al, 11 % decrease). This exemplifies the changes induced upon combining both the active zeolite phase and the binder material in extrudates, with the decrease in pore volume attributed to blockage/coverage of the binder pores with ZSM‐5 crystals/agglomerates and/or morphological changes in the binder. Corresponding pore‐size distributions are illustrated in Figure 1. Noticeably, the ZSM‐5‐based SiO2‐bound extrudates express a far wider pore‐size distribution than their Al2O3‐bound counterparts. An increase in active‐phase content creates a narrower pore‐size distribution in both cases, owing to the lower contribution of mesopores from the decreased binder content.

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