Cooperative Catalysis by Surface Lewis Acid/Silanol for Selective Fructose Etherification on Sn-SPP Zeolite

Tyler R. Josephson, Robert F. Dejaco, Swagata Pahari, Limin Ren, Qiang Guo, Michael Tsapatsis, J. Ilja Siepmann, Dionisios G. Vlachos, Stavros Caratzoulas

Research output: Contribution to journalArticlepeer-review

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Abstract

While Lewis-acid zeolites, such as Sn-Beta, catalyze glucose isomerization in an alcoholic medium, mesoporous Sn-SPP catalyzes both glucose isomerization to fructose and fructose etherification (formally ketalization) to ethyl fructoside, enabling fructose yields in excess of the glucose/fructose equilibrium. Using periodic density functional theory calculations and force-field-based Monte Carlo simulations, the ketalization reaction mechanism and adsorption behavior were examined. The silanols on the Sn-SPP mesopore surface facilitate the ketalization reaction through hydrogen bonding interactions at the transition state, only possible via a Sn-O-Si-OH moiety, present in Sn-SPP but not in Sn-Beta. Fructose ketalization is favored over glucose acetalization due to differences in stability of the oxonium intermediates, which are stabilized by the Sn-SPP active site. The open site of hydrophobic Sn-Beta cannot perform these reactions because its active site does not contain an adjacent silanol of the right geometry. In addition to the more favorable activation barrier of the catalytic process, the adsorption at the catalytic site in Sn-SPP is also found to be more favorable than for Sn-Beta, in spite of competitive adsorption between fructose and ethanol in the ethanol-saturated zeolites.

Original languageEnglish (US)
Pages (from-to)9056-9065
Number of pages10
JournalACS Catalysis
Volume8
Issue number10
DOIs
StatePublished - Oct 5 2018

Bibliographical note

Funding Information:
Financial support through the Catalysis Center for Energy Innovation, a U.S. Department of Energy − Energy Frontier Research Center under Grant No. DE-SC0001004, is gratefully acknowledged. Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC02-05CH11231, Information Technologies (IT) at the University of Delaware, and the Minnesota Supercomputing Institute (MSI) at the University of Minnesota.

Funding Information:
Financial support through the Catalysis Center for Energy Innovation, a U.S. Department of Energy Energy Frontier Research Center under Grant No. DE-SC0001004, is gratefully acknowledged. Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC02-05CH11231, Information Technologies (IT) at the University of Delaware and the Minnesota Supercomputing Institute (MSI) at the University of Minnesota.

Publisher Copyright:
© 2018 American Chemical Society.

Keywords

  • Gibbs ensemble Monte Carlo
  • acetalization
  • adsorption
  • biomass processing
  • ketalization
  • sugars chemistry

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