Stoichiometric Active Site Modification Observed by Alkali Ion Titrations of Sn-Beta

Samuel Gilbert Elliot, Irene Tosi, Sebastian Meier, Juan S. Martinez-Espin, Søren Tolborg, Esben Taarning*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Sn-Beta zeolite can convert carbohydrate feedstocks through different pathways into a variety of chemical building blocks. Alkali salts influence the selectivity between these pathways, but the details of the alkali ion effect on the catalyst have remained unclear. Here, we combine the systematic variation of tin content in Sn-Beta zeolite with alkali ion titrations and functional assays to assess the stochiometry of alkali binding and the prospect of predicting operation optima from catalyst properties. The approach is used to evaluate the product selectivity of defined catalyst states for the conversion of glucose to methyl lactate formation and to characterise the catalytic behavior of the active site with respect to the degree of titration. The optimum selectivity to methyl lactate was found at similar ratios of alkali and active tin for catalyst of different tin loadings, indicating a stochiometric correlation between added alkali ions and tin content in the Sn-Beta zeolite. The observations also indicate that a double dissociation of the active site occurs and that titration between three states is
possible. The proton form of Sn-Beta has a poor methyl lactate selectivity, whereas a single exchange of a proton by potassium at the active site leads to a catalytic form with a very high selectivity, while double exchange leads to a catalytically inactive state of the active site. Exchange phenomena at the active site were corroborated by FT-IR spectroscopy, which showed that potassium interacts with hydroxyl groups in the vicinity of Sn.
Original languageEnglish
JournalCatalysis Science & Technology
Volume9
Issue number16
Pages (from-to)4339-4346
Number of pages7
ISSN2044-4753
DOIs
Publication statusPublished - 2019

Cite this

Elliot, S. G., Tosi, I., Meier, S., Martinez-Espin, J. S., Tolborg, S., & Taarning, E. (2019). Stoichiometric Active Site Modification Observed by Alkali Ion Titrations of Sn-Beta. Catalysis Science & Technology, 9(16), 4339-4346. https://doi.org/10.1039/C9CY01189G
Elliot, Samuel Gilbert ; Tosi, Irene ; Meier, Sebastian ; Martinez-Espin, Juan S. ; Tolborg, Søren ; Taarning, Esben. / Stoichiometric Active Site Modification Observed by Alkali Ion Titrations of Sn-Beta. In: Catalysis Science & Technology. 2019 ; Vol. 9, No. 16. pp. 4339-4346.
@article{46a9832cbf024ed3b3e2410a4b15d5f3,
title = "Stoichiometric Active Site Modification Observed by Alkali Ion Titrations of Sn-Beta",
abstract = "Sn-Beta zeolite can convert carbohydrate feedstocks through different pathways into a variety of chemical building blocks. Alkali salts influence the selectivity between these pathways, but the details of the alkali ion effect on the catalyst have remained unclear. Here, we combine the systematic variation of tin content in Sn-Beta zeolite with alkali ion titrations and functional assays to assess the stochiometry of alkali binding and the prospect of predicting operation optima from catalyst properties. The approach is used to evaluate the product selectivity of defined catalyst states for the conversion of glucose to methyl lactate formation and to characterise the catalytic behavior of the active site with respect to the degree of titration. The optimum selectivity to methyl lactate was found at similar ratios of alkali and active tin for catalyst of different tin loadings, indicating a stochiometric correlation between added alkali ions and tin content in the Sn-Beta zeolite. The observations also indicate that a double dissociation of the active site occurs and that titration between three states ispossible. The proton form of Sn-Beta has a poor methyl lactate selectivity, whereas a single exchange of a proton by potassium at the active site leads to a catalytic form with a very high selectivity, while double exchange leads to a catalytically inactive state of the active site. Exchange phenomena at the active site were corroborated by FT-IR spectroscopy, which showed that potassium interacts with hydroxyl groups in the vicinity of Sn.",
author = "Elliot, {Samuel Gilbert} and Irene Tosi and Sebastian Meier and Martinez-Espin, {Juan S.} and S{\o}ren Tolborg and Esben Taarning",
year = "2019",
doi = "10.1039/C9CY01189G",
language = "English",
volume = "9",
pages = "4339--4346",
journal = "Catalysis Science & Technology",
issn = "2044-4753",
publisher = "Royal Society of Chemistry",
number = "16",

}

Elliot, SG, Tosi, I, Meier, S, Martinez-Espin, JS, Tolborg, S & Taarning, E 2019, 'Stoichiometric Active Site Modification Observed by Alkali Ion Titrations of Sn-Beta', Catalysis Science & Technology, vol. 9, no. 16, pp. 4339-4346. https://doi.org/10.1039/C9CY01189G

Stoichiometric Active Site Modification Observed by Alkali Ion Titrations of Sn-Beta. / Elliot, Samuel Gilbert; Tosi, Irene; Meier, Sebastian; Martinez-Espin, Juan S.; Tolborg, Søren; Taarning, Esben.

In: Catalysis Science & Technology, Vol. 9, No. 16, 2019, p. 4339-4346.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Stoichiometric Active Site Modification Observed by Alkali Ion Titrations of Sn-Beta

AU - Elliot, Samuel Gilbert

AU - Tosi, Irene

AU - Meier, Sebastian

AU - Martinez-Espin, Juan S.

AU - Tolborg, Søren

AU - Taarning, Esben

PY - 2019

Y1 - 2019

N2 - Sn-Beta zeolite can convert carbohydrate feedstocks through different pathways into a variety of chemical building blocks. Alkali salts influence the selectivity between these pathways, but the details of the alkali ion effect on the catalyst have remained unclear. Here, we combine the systematic variation of tin content in Sn-Beta zeolite with alkali ion titrations and functional assays to assess the stochiometry of alkali binding and the prospect of predicting operation optima from catalyst properties. The approach is used to evaluate the product selectivity of defined catalyst states for the conversion of glucose to methyl lactate formation and to characterise the catalytic behavior of the active site with respect to the degree of titration. The optimum selectivity to methyl lactate was found at similar ratios of alkali and active tin for catalyst of different tin loadings, indicating a stochiometric correlation between added alkali ions and tin content in the Sn-Beta zeolite. The observations also indicate that a double dissociation of the active site occurs and that titration between three states ispossible. The proton form of Sn-Beta has a poor methyl lactate selectivity, whereas a single exchange of a proton by potassium at the active site leads to a catalytic form with a very high selectivity, while double exchange leads to a catalytically inactive state of the active site. Exchange phenomena at the active site were corroborated by FT-IR spectroscopy, which showed that potassium interacts with hydroxyl groups in the vicinity of Sn.

AB - Sn-Beta zeolite can convert carbohydrate feedstocks through different pathways into a variety of chemical building blocks. Alkali salts influence the selectivity between these pathways, but the details of the alkali ion effect on the catalyst have remained unclear. Here, we combine the systematic variation of tin content in Sn-Beta zeolite with alkali ion titrations and functional assays to assess the stochiometry of alkali binding and the prospect of predicting operation optima from catalyst properties. The approach is used to evaluate the product selectivity of defined catalyst states for the conversion of glucose to methyl lactate formation and to characterise the catalytic behavior of the active site with respect to the degree of titration. The optimum selectivity to methyl lactate was found at similar ratios of alkali and active tin for catalyst of different tin loadings, indicating a stochiometric correlation between added alkali ions and tin content in the Sn-Beta zeolite. The observations also indicate that a double dissociation of the active site occurs and that titration between three states ispossible. The proton form of Sn-Beta has a poor methyl lactate selectivity, whereas a single exchange of a proton by potassium at the active site leads to a catalytic form with a very high selectivity, while double exchange leads to a catalytically inactive state of the active site. Exchange phenomena at the active site were corroborated by FT-IR spectroscopy, which showed that potassium interacts with hydroxyl groups in the vicinity of Sn.

U2 - 10.1039/C9CY01189G

DO - 10.1039/C9CY01189G

M3 - Journal article

VL - 9

SP - 4339

EP - 4346

JO - Catalysis Science & Technology

JF - Catalysis Science & Technology

SN - 2044-4753

IS - 16

ER -