Effects of Alkali and Counter Ions in Sn-Beta Catalyzed Carbohydrate Conversion

Samuel G. Elliot, Søren Tolborg, Robert Madsen, Esben Taarning, Sebastian Meier*

*Corresponding author for this work

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Abstract

Alkali ions have been shown to strongly influence the catalytic behavior of stannosilicates in the conversion of carbohydrates. An effect of having alkali ions present is a pronounced increase in selectivity towards methyl lactate. Mechanistic details of this effect have remained obscure and are herein addressed experimentally through kinetic experiments and isotope tracking. Alkali ions have a differential effect in competing reaction pathways: they promote the rate of carbon-carbon bond breakage of carbohydrate substrates, but decrease the rates of competing dehydration pathways. Further addition of alkali inhibits activity of Sn-Beta in all major reaction pathways. The alkali effects on product distributions and on rates of product formation are similar, thus pointing to a kinetic reaction control and to irreversible reaction steps in the main pathways. Additionally, an effect of the accompanying basic anions is shown, supposedly facilitating the cation exchange and eliciting a different concentration-dependent effect than neutral alkali salts.
Original languageEnglish
JournalChemSusChem (Print)
Volume11
Issue number7
Pages (from-to)1198-1203
Number of pages6
ISSN1864-5631
DOIs
Publication statusPublished - 2018

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